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Patent Abstract
An apparatus includes a linear solenoid valve regulating an oil
pressure supplied to a clutch, a hydraulic switch being switched
on and off upon receipt of a switching oil pressure, and a control
unit controlling the actuation of the solenoid valve. A pressure-increased
side signal oil pressure is detected which results when the hydraulic
switch is switched on and off while a control signal is sent to
the solenoid valve to increase a control oil pressure from a predetermined
lower pressure to a predetermined higher pressure, and a pressure-decreased
side signal oil pressure is detected which results when the hydraulic
switch is switched on and off while the control signal is sent to
decrease the control oil pressure from the predetermined higher
pressure to the predetermined lower pressure. When a difference
between these signal oil pressures exceeds an abnormalities determination
value, it is determined that the solenoid valve is abnormal.
Patent Claims
What is claimed is:
1. An apparatus for detecting an abnormality of a linear solenoid
valve comprising: the linear solenoid valve for regulating a control
oil pressure that is supplied to a hydraulic device based on a control
signal; a hydraulic switch set to be switched on and off when an
oil pressure variation is applied thereto which overpasses a predetermined
switching oil pressure, the hydraulic switch being disposed in such
a manner as to receive the control oil pressure regulated by the
linear solenoid valve; and a valve actuating controller sending
out the control signal to the linear solenoid valve, wherein the
control signal is sent from the valve actuating controller to the
linear solenoid valve to increase the control oil pressure from
a predetermined lower pressure which is lower than the switching
oil pressure to a predetermined higher pressure which is higher
than the switching oil pressure to thereby cause the linear solenoid
valve to regulate the control oil pressure, during which, when the
hydraulic pressure switch is switched on and off, a pressure-increased
side signal oil pressure is detected which corresponds to the control
signal outputted from the valve actuating controller, wherein the
control signal is sent from the valve actuating controller to the
linear solenoid valve to decrease the control oil pressure from
the predetermined higher pressure to the predetermined lower pressure,
during which, when the hydraulic pressure switch is switched on
and off a pressure-decreased side signal oil pressure is detected
which corresponds to the control signal outputted from the valve
actuating controller, and wherein the linear solenoid valve is diagnosed
as being abnormal when a difference between the pressure-increased
side signal oil pressure and the pressure-decreased side control
oil pressure exceeds an abnormality determination value.
2. A method for detecting the existence of an abnormality of a
linear solenoid valve for regulating a control oil pressure that
is supplied to a hydraulic device based on a control signal, the
method comprising the steps of: preparing a hydraulic switch disposed
at a position receiving the control oil pressure which has been
regulated by the linear solenoid valve and set to be switched on
and off when an oil pressure variation is applied thereto which
overpasses a predetermined switching oil pressure; first sending
the control signal to the linear solenoid valve to increase the
control oil pressure from a predetermined lower pressure which is
lower than the switching oil pressure to a predetermined higher
pressure which is higher than the switching oil pressure, while
the first sending step is being implemented, detecting a pressure-increased
side signal oil pressure which corresponds to the control signal
resulting when the hydraulic pressure switch is switched on and
off upon receipt of the control oil pressure which has been regulated
by the linear solenoid valve, second sending the control signal
to the linear solenoid valve to decrease the control oil pressure
from the predetermined higher pressure to the predetermined lower
pressure, while the second sending step is being implemented, detecting
a pressure-decreased side signal oil pressure which corresponds
to the control signal resulting when the hydraulic pressure switch
is switched on and off upon receipt of the control oil pressure
which has been regulated by the linear solenoid valve, and diagnosing
that the linear solenoid valve is abnormal when a difference between
the pressure-increased side signal oil pressure and the pressure-decreased
side control oil pressure exceeds an abnormality determination value.
3. An apparatus for detecting abnormalities of a hydraulic device
comprising: a frictional engagement element adapted to be brought
into engagement upon receipt of an oil pressure force, a linear
solenoid valve for regulating an engagement control oil pressure
which is supplied to the frictional engagement element; a hydraulic
switch set to be switched on and off when an oil pressure variation
is applied thereto which overpasses a switching oil pressure which
is an engagement control oil pressure at which the frictional engagement
element starts to be brought into engagement, the hydraulic switch
being disposed in such a manner as to receive the control oil pressure
that has been regulated by the linear solenoid valve; and a valve
actuating controller for controlling the actuation of the linear
solenoid valve so as to make the linear solenoid valve implement
the regulation of the engagement control oil pressure, wherein the
control signal is sent from the valve actuating controller to the
linear solenoid valve to increase the engagement control oil pressure
from a predetermined lower pressure which is lower than the switching
oil pressure to a predetermined higher pressure which is higher
than the switching oil pressure to thereby cause the linear solenoid
valve to regulate the engagement control oil pressure, during which,
when the hydraulic switch is switched on and off, a first pressure-increased
side signal oil pressure is detected which corresponds to the control
signal outputted from the valve actuating controller, wherein the
control signal is sent from the valve actuating controller to the
linear solenoid valve to decrease the engagement control oil pressure
from the predetermined higher pressure to the predetermined lower
pressure, during which, when the hydraulic switch is switched on
and off, a first pressure-decreased side signal oil pressure is
detected which corresponds to the control signal outputted from
the valve actuating controller, and wherein the linear solenoid
valve is diagnosed as being abnormal when a difference between the
first pressure-increased side signal oil pressure and the first
pressure-decreased side control oil pressure exceeds a first abnormality
determination value.
4. The apparatus for detecting abnormalities as set forth in claim
3, comprising: an engagement detection unit detecting an engagement
of the frictional engagement element, wherein the control signal
is sent from the valve actuating controller to the linear solenoid
valve to increase the engagement control oil pressure-from the predetermined
lower pressure to the predetermined higher pressure to thereby cause
the linear solenoid valve to regulate the frictional engagement
control oil pressure, during which a second pressure-increased side
signal oil pressure is detected which corresponds to the control
signal resulting when the start of engagement of the frictional
engagement element is detected by the engagement detection unit,
and wherein the hydraulic switch is diagnosed as being abnormal
when a difference between the first pressure-increased side signal
oil pressure and the second pressure-increased side signal oil pressure
exceeds a second abnormality determination value.
5. The apparatus for detecting abnormalities as set forth in claim
3, comprising: an engagement detection unit detecting an engagement
of the frictional engagement element, wherein the control signal
is sent from the valve actuating controller to the linear solenoid
valve to decrease the engagement control oil pressure from the predetermined
higher pressure to the predetermined lower pressure to thereby cause
the linear solenoid valve to regulate the frictional engagement
control oil pressure, during which a second pressure-decreased side
signal oil pressure is detected which corresponds to the control
signal resulting when the start of release of the frictional engagement
element is detected by the engagement detection unit, and wherein
the hydraulic switch is diagnosed as being abnormal when a difference
between the first pressure-decreased side signal oil pressure and
the second pressure-decreased side signal oil pressure exceeds a
third abnormality determination value.
6. The apparatus for detecting abnormalities as set forth in claim
4, wherein the frictional engagement element is used as a clutch
for a transmission for controlling speed changes of a vehicle or
as a brake, and wherein the detection of engagement of the frictional
engagement element by the engagement detection unit is implemented
with the vehicle being at halt, the brakes of the vehicle being
applied and an engine of the vehicle being in an idle state.
7. An apparatus for detecting abnormalities as set forth in claim
6, wherein a torque converter is disposed at an input portion of
the transmission in such a manner as to be connected to an output
shaft of the engine, and wherein a transmission mechanism whose
actuation is controlled by the frictional engagement element is
disposed in such a manner as to be connected to an output side of
the torque converter.
8. The apparatus for detecting abnormalities as set forth in claim
5, wherein the frictional engagement element is used as a clutch
for a transmission for controlling speed changes of a vehicle or
as a brake, and wherein the detection of engagement of the frictional
engagement element by the engagement detection unit is implemented
with the vehicle being at halt, the brakes of the vehicle being
applied and an engine of the vehicle being in an idle state.
9. An apparatus for detecting abnormalities as set forth in claim
8, wherein a torque converter is disposed at an input portion of
the transmission in such a manner as to be connected to an output
shaft of the engine, and wherein a transmission mechanism whose
actuation is controlled by the frictional engagement element is
disposed in such a manner as to be connected to an output side of
the torque converter.
10. A method for detecting the existence of an abnormality of a
linear solenoid valve for regulating based on a control signal an
engagement control oil pressure which is supplied to a frictional
engagement element adapted to be brought into engagement upon receipt
of an oil pressure force, the method comprising the steps of: preparing
a hydraulic switch set to be switched on and off when an oil pressure
variation is applied thereto which overpasses a predetermined switching
oil pressure, the hydraulic switch being disposed at a position
to receive the engagement control oil pressure regulated by the
linear solenoid valve and is set to be switched on and off at an
engagement control oil pressure at which the frictional engagement
element starts to be brought into engagement and which acts as the
switching oil pressure; first sending the control signal to the
linear solenoid valve to increase the engagement control oil pressure
from a predetermined lower pressure which is lower than the switching
oil pressure to a predetermined higher pressure which is higher
than the switching oil pressure; while the first sending step is
being implemented, detecting a first pressure-increased side signal
oil pressure which corresponds to the control signal resulting when
the hydraulic switch is switched on and off upon receipt of the
engagement control oil pressure regulated by the linear solenoid
valve; second sending a control signal to the linear solenoid valve
to decrease the engagement control oil pressure from the predetermined
higher pressure to the predetermined lower pressure; while the second
sending step is being implemented, detecting a first pressure-decreased
side signal oil pressure which corresponds to the control signal
resulting when the hydraulic switch is switched on and off upon
receipt of the engagement control oil pressure regulated by the
linear solenoid valve; and diagnosing the linear solenoid valve
as being abnormal when a difference between the first pressure-increased
side signal oil pressure and the first pressure-decreased side control
oil pressure exceeds a first abnormality determination value.
11. The method for detecting abnormalities as set forth in claim
10, further comprising the steps of: detecting an engagement of
the frictional engagement element when making the linear solenoid
valve implement the regulation of the engagement control oil pressure
by sending the control signal to the linear solenoid valve to increase
the engagement control oil pressure from the predetermined lower
pressure to the predetermined higher pressure, detecting a second
pressure-increased side signal oil pressure which corresponds to
the control signal resulting when the engagement of the frictional
engagement element is started, diagnosing the hydraulic switch as
being abnormal when a difference between the first pressure-increased
side signal oil pressure and the second pressure-increased side
signal oil pressure exceeds a second abnormality determination value.
12. The method for detecting abnormalities as set forth in claim
10, further comprising the steps of: detecting an engagement of
the frictional engagement element when making the linear solenoid
valve implement the regulation of the engagement control oil pressure
by sending a control signal to the linear solenoid valve to decrease
the engagement control oil pressure from the predetermined higher
pressure to the predetermined lower pressure; detecting a second
pressure-decreased side signal oil pressure which corresponds to
the control signal resulting when the release of the frictional
engagement element is started; and diagnosing the hydraulic switch
as being abnormal when a difference between the first pressure-decreased
side signal oil pressure and the second pressure-decreased side
signal oil pressure exceeds a third abnormality determination value.
Patent Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an apparatus and a method
for detecting abnormalities of a linear solenoid valve for regulating
a control oil pressure that is supplied to a hydraulic device based
on a control signal (an electric signal). The invention relates
more particularly to an apparatus and a method for detecting abnormalities
of a hydraulic device having a frictional engagement element such
as a hydraulically actuated clutch or brake adapted to be brought
into engagement upon receipt of an oil pressure force and a linear
solenoid valve for regulating an actuation control oil pressure
that is supplied to the frictional engagement element.
[0003] 2. Description of the Related Art
[0004] A hydraulic device is used as, for example, a transmission
in an automotive automatic transmission or the like, and in general,
the transmission is constructed so as to automatically control speed
changes according to the opening of an accelerator and the vehicle
speed. The transmission for performing such automatic speed changes
is constructed to have gear trains constituting a plurality of power
transmission paths, and the gear trains are automatically changed
over to select any of the power transmission paths by controlling
the engagement of frictional engagement elements (a hydraulic clutch,
brakes and the like), whereby the speed change control is implemented.
In a known engagement control of a frictional engagement element,
the control is performed by controlling the supply of working oil
pressure (engagement control oil pressure), and in many cases a
solenoid valve is used to control the supply of working oil pressure
in an electric fashion. In this case, since the malfunction of the
solenoid valve results in a failure of change-speed control, it
is important to detect abnormalities of the solenoid valve. For
example, JP-A-2000-266176 discloses an apparatus for detecting abnormalities
of a solenoid valve.
[0005] In recent automatic transmissions, in many cases, controlling
the regulation of engagement control oil pressure is implemented
by a linear solenoid valve. In a case where a linear solenoid valve
is used to implement controlling the engagement of a frictional
engagement element to thereby perform change-speed controlling,
it is possible to freely regulate an engagement control oil pressure
which is supplied to the frictional engagement element by controlling
energizing of the linear solenoid valve, and this provides an advantage
that the degree of freedom in setting an engagement control oil
pressure at the time of changing speeds becomes large. However,
in case there occurs an abnormality in the linear solenoid valve,
it becomes impossible to control the regulation of change-speed
control oil pressure, this causing a problem that the change-speed
control becomes imprecise. Owing to this, conventionally, an oil
pressure sensor for measuring an engagement control oil pressure
outputted from the linear solenoid valve is mounted on a change-speed
control device externally, and an engagement control oil pressure
outputted from the linear solenoid valve relative to a control signal
inputted into the linear solenoid valve is detected with the hydraulic
sensor to thereby detect the existence of abnormalities of the linear
solenoid valve.
[0006] Incidentally, in an automatic transmission, there is no
need to use an oil pressure sensor, and in general there is mounted
no oil pressure sensor, and therefore, every time an abnormality
detection is implemented, an oil pressure sensor is mounted externally
on the automatic transmission to detect abnormalities of the linear
solenoid valves, this causing a problem that abnormality detection
can be carried out only at limited places such as plants and dealerships.
In addition, oil pressure sensors are expensive, and this causes
a problem that there is provided an expensive abnormality detector.
Furthermore, there is caused a problem that there is a risk of dust
or foreign matters entering the hydraulic device when the oil pressure
sensor is attached to and detached from the same device.
SUMMARY OF THE INVENTION
[0007] The invention was made in view of the above problems and
an object thereof is to provide an apparatus and a method for detecting
abnormalities of a linear solenoid valve and a hydraulic device
using the linear solenoid valve with ease. In particular, an object
of the invention is to provide an apparatus and a method for detecting
abnormalities of a linear solenoid valve and a hydraulic device
using the linear solenoid valve by having a hydraulic switch which
is inexpensive and is equipped within an oil pressure controller
of an automatic transmission in many cases.
[0008] With a view to attaining the objects, according to an aspect
of the invention, there is provided an apparatus for detecting abnormalities
of a linear solenoid valve comprising a linear solenoid valve (for
example, first to third linear solenoid valves 51, 52, 53 in an
embodiment) for regulating a control oil pressure that is supplied
to a hydraulic device (for example, a second clutch 12, a third
clutch 13 in the embodiment) based on a control signal, a hydraulic
switch (for example, first and second hydraulic switches 61, 62
in the embodiment) set to be switched on and off when an oil pressure
variation is applied thereto which overpasses a predetermined switching
oil pressure, and a valve actuating controller (for example, an
electronic control unit 60, an external diagnosis unit 70 or the
line in the embodiment) for sending out the control signal to the
linear solenoid valve, wherein the hydraulic switch is disposed
in such a manner as to receive the control oil pressure that has
been regulated by the linear solenoid valve. A control signal is
sent from the valve actuating controller to the linear solenoid
valve to increase the control oil pressure from a predetermined
lower pressure which is lower than the switching oil pressure to
a predetermined higher pressure which is higher than the switching
oil pressure to thereby cause the linear solenoid valve to regulate
the control oil pressure, during which, when the hydraulic switch
is switched on and off a pressure-increased side signal oil pressure
is detected which corresponds to the control signal outputted from
the valve actuating controller. And, a control signal is sent from
the valve actuating controller to the linear solenoid valve to decrease
the control oil pressure from the predetermined higher pressure
to the predetermined lower pressure to thereby cause the linear
solenoid valve to regulate the working oil pressure, during which,
when the hydraulic switch is switched on and off a pressure-decreased
side signal oil pressure is detected which corresponds to the control
signal outputted from the valve actuating controller. Further, the
linear solenoid valve is diagnosed as being abnormal when a difference
between the pressure-increased side signal oil pressure and the
pressure-decreased side signal oil pressure exceeds an abnormality
determination value.
[0009] In addition, according to another aspect of the invention,
there is provided a method for detecting the existence of an abnormality
of a linear solenoid valve for regulating a control oil pressure
that is supplied to a hydraulic device based on a control signal
using a hydraulic switch disposed at a position to receive the control
oil pressure which has been regulated by the linear solenoid valve
and set to be switched on and off when an oil pressure variation
is applied thereto which overpasses a predetermined switching oil
pressure, and the method comprises the steps of, firstly, sending
a control signal to the linear solenoid valve to increase the control
oil pressure from a predetermined lower pressure which is lower
than the switching oil pressure to a predetermined higher pressure
which is higher than the switching oil pressure, while the above
step is being implemented, detecting a pressure-increased side signal
oil pressure which corresponds to the control signal resulting when
the hydraulic switch is switched on and off upon receipt of the
control oil pressure which has been regulated by the linear solenoid
valve, sending a control signal to the linear solenoid valve to
decrease the control oil pressure from the predetermined higher
pressure to the predetermined lower pressure, while the above step
is being implemented, detecting a pressure-decreased side signal
oil pressure which corresponds to the control signal resulting when
the hydraulic switch is switched on and off upon receipt of the
control oil pressure which has been regulated by the linear solenoid
valve, and diagnosing that the linear solenoid valve is abnormal
when a difference between the pressure-increased side signal oil
pressure and the pressure-decreased side control oil pressure exceeds
an abnormality determination value.
[0010] The hydraulic switch is switched on and off when the engagement
control oil pressure varies in such a manner as to overpass the
switching oil pressure both when the engagement control oil pressure
varies to increase and when the engagement control oil pressure
varies to decrease, and even in consideration of a control response
delay, the difference between the first pressure-increased side
signal oil pressure and the first pressure-decreased side signal
oil pressure must be small. Namely, with the difference being large,
it is determined that the linear solenoid valve is being abnormal.
According to the invention, the detection of abnormalities of the
linear solenoid valve is implemented based on such a determination,
and according to the apparatus and method for detecting abnormalities
of the linear solenoid as described above, the existence of abnormalities
of the linear solenoid valve can be detected easily by using the
relatively inexpensive hydraulic switch (without using an oil pressure
sensor for detecting the value of an oil pressure).
[0011] According to a further aspect of the invention, there is
provided an apparatus for detecting abnormalities of a hydraulic
device comprising a frictional engagement element (for example,
a LOW clutch 11, a second clutch 12, a third clutch 13, a fourth
clutch 14, a fifth clutch 15 or the like in the embodiment) adapted
to be brought into engagement upon receipt of an oil pressure force,
a linear solenoid valve (for example, the first to third linear
solenoid valves 51, 52, 53 in the embodiment) for regulating an
engagement control oil pressure which is supplied to the frictional
engagement element, a hydraulic switch (for example, the first and
second hydraulic switches, 61, 62 in the embodiment) set to be switched
on and off when an oil pressure variation is applied thereto which
overpasses a switching oil pressure which is an engagement control
oil pressure at which the frictional engagement element starts to
be brought into engagement and a valve actuating controller (for
example, the electronic control unit 60, the external diagnosis
unit 70 or the like in the embodiment) for controlling the actuation
of the linear solenoid valve so as to make the linear solenoid valve
implement the regulation of the engagement control oil pressure,
wherein the hydraulic switch is disposed in such a manner as to
receive the control oil pressure that has been regulated by the
linear solenoid valve, wherein a control signal is sent from the
valve actuating controller to the linear solenoid valve to increase
the engagement control oil pressure from a predetermined lower pressure
which is lower than the switching oil pressure to a predetermined
higher pressure which is higher than the switching oil pressure
to thereby cause the linear solenoid valve to regulate the engagement
control oil pressure, during which, when the hydraulic switch is
switched on and off a first pressure-increased side signal oil pressure
is detected which corresponds to the control signal outputted from
the valve actuating controller, and wherein a control signal is
sent from the valve actuating controller to the linear solenoid
valve to decrease the engagement control oil pressure from the predetermined
higher pressure to the predetermined lower pressure, during which,
when the hydraulic switch is switched on and off a first pressure-decreased
side signal oil pressure is detected which corresponds to the control
signal outputted from the valve actuating controller, whereby the
linear solenoid valve is diagnosed as being abnormal when a difference
between the first pressure-increased side signal oil pressure and
the first pressure-decreased side control oil pressure exceeds a
first abnormality determination value.
[0012] With the abnormality detecting apparatus constructed as
described above, the existence of abnormalities of the linear solenoid
valve can be detected easily by using the relatively inexpensive
hydraulic switch (without using an oil pressure sensor for detecting
the value of an oil pressure). In addition, in many cases, the hydraulic
switch is provided on the hydraulic device such as a change-speed
control valve in an automatic transmission, and as this occurs,
it is possible to construct such that the detection of abnormalities
can be implemented easily without requiring the selection of a place
by using the hydraulic switch.
[0013] According to another aspect of the invention, the apparatus
for detecting abnormalities is provided with an engagement detection
unit (for example, the electronic control unit 60 adapted to be
actuated upon receipt of a detection signal from an engine speed
sensor 65 in the embodiment) for detecting an engagement of the
frictional engagement element, wherein a control signal is sent
from the valve actuating controller to the linear solenoid valve
to increase the engagement control oil pressure from the predetermined
lower pressure to the predetermined higher pressure to thereby cause
the linear solenoid valve to regulate the frictional engagement
control oil pressure, during which a second pressure-increased side
signal oil pressure resulting when the engagement of the frictional
engagement element is started is detected by the engagement detection
unit, whereby the hydraulic switch may be diagnosed as being abnormal
when a difference between the first pressure-increased side signal
oil pressure and the second pressure-increased side signal oil pressure
exceeds a second abnormality determination value.
[0014] According to a further aspect of the invention, the apparatus
for detecting abnormalities is provided with an engagement detection
unit for detecting an engagement of the frictional engagement element,
wherein a control signal is sent from the valve actuating controller
to the linear solenoid valve to decrease the engagement control
oil pressure from the predetermined higher pressure to the predetermined
lower pressure to thereby cause the linear solenoid valve to regulate
the frictional engagement control oil pressure, during which a second
pressure-decreased side signal oil pressure resulting when the release
of the frictional engagement element is started is detected by the
engagement detection unit, whereby the hydraulic switch is diagnosed
as being abnormal when a difference between the first pressure-decreased
side signal oil pressure and the second pressure-decreased side
signal oil pressure exceeds a third abnormality determination value.
[0015] The hydraulic switch is set to use as the switching oil
pressure the engagement control oil pressure at which the engagement
of the frictional engagement element is started, and as described
above, in the event that the difference between the first pressure-increased
side signal oil pressure and the second pressure-increased side
signal oil pressure exceeds the second abnormality determination
value, or in the event that the difference between the first pressure-decreased
side signal oil pressure and the second pressure-decreased side
signal oil pressure exceeds the third abnormality determination
value, it is considered that an abnormality is being caused such
as the set switching oil pressure at which the hydraulic switch
is switched on and off is deviated or the hydraulic switch fails
to operate properly. Then, according to the invention, abnormalities
of the hydraulic switch can also be detected based on the above
determination.
[0016] In addition, in the invention, in the event that the frictional
engagement element is used as a clutch for a transmission for controlling
speed changes of a vehicle or as a brake, the detection of engagement
of the frictional engagement element by the engagement detection
unit is implemented with the vehicle being at halt, the brakes of
the vehicle being applied and an engine of the vehicle being in
an idle state. Furthermore, in a construction in which a torque
converter is disposed at an input portion of the transmission in
such a manner as to be connected to an output shaft of the engine
and in which a transmission mechanism whose actuation is controlled
by the frictional engagement element is provided in such a manner
as to be connected to an output side of the torque converter, it
is preferable that abnormalities are detected with the abnormality
detecting apparatus according to the invention.
[0017] According to a further aspect of the invention, there is
provided a method for detecting the existence of an abnormality
of a linear solenoid valve for regulating based on a control signal
an engagement control oil pressure which is supplied to a frictional
engagement element adapted to be brought into engagement upon receipt
of an oil pressure force using a hydraulic switch set to be switched
on and off when an oil pressure variation is applied thereto which
overpasses a predetermined switching oil pressure, wherein the hydraulic
switch is disposed at a position to receive the control oil pressure
that has been regulated by the linear solenoid valve and is set
to be switched on and off at an engagement control oil pressure
at which the frictional engagement element starts to be brought
into engagement and which acts as the switching oil pressure. The
method comprises the steps of sending a control signal to the linear
solenoid valve to increase the engagement control oil pressure from
a predetermined lower pressure which is lower than the switching
oil pressure to a predetermined higher pressure which is higher
than the switching oil pressure, while the above step is being implemented,
detecting a first pressure-increased side signal oil pressure which
corresponds to the control signal resulting when the hydraulic switch
is switched on and off upon receipt of the engagement control oil
pressure which has been regulated by the linear solenoid valve,
sending a control signal to the linear solenoid valve to decrease
the engagement control oil pressure from the predetermined higher
pressure to the predetermined lower pressure, while the above step
is being implemented, detecting a first pressure-decreased side
signal oil pressure which corresponds to the control signal resulting
when the hydraulic switch is switched on and off upon receipt of
the engagement control oil pressure which has been regulated by
the linear solenoid valve, whereby the linear solenoid valve is
diagnosed as being abnormal when a difference between the first
pressure-increased side signal oil pressure and the first pressure-decreased
side control oil pressure exceeds a first abnormality determination
value.
[0018] The above abnormality detecting method may comprise further
the steps of detecting an engagement of the frictional engagement
element when making the linear solenoid valve implement the regulation
of the engagement control oil pressure by sending a control signal
to the linear solenoid valve to increase the engagement control
oil pressure from the predetermined lower pressure to the predetermined
higher pressure, detecting a second pressure-increased side signal
oil pressure which corresponds to the control signal resulting when
the engagement of the frictional engagement element is started,
whereby the hydraulic switch is diagnosed as being abnormal when
a difference between the first pressure-increased side signal oil
pressure and the second pressure-increased side signal oil pressure
exceeds a second abnormality determination value.
[0019] The above abnormality detecting method may comprise further
the steps of detecting an engagement of the frictional engagement
element when making the linear solenoid valve implement the regulation
of the engagement control oil pressure by sending a control signal
to the linear solenoid valve to decrease the engagement control
oil pressure from the predetermined higher pressure to the predetermined
lower pressure, detecting a second pressure-decreased side signal
oil pressure which corresponds to the control signal resulting when
the release of the frictional engagement element is started, whereby
the hydraulic switch is diagnosed as being abnormal when a difference
between the first pressure-decreased side signal oil pressure and
the second pressure-decreased side signal oil pressure exceeds a
third abnormality determination value.
[0020] According to the abnormality detecting method of the invention
which is constructed as has been described heretofore, the existence
of abnormalities of the linear solenoid valve can be detected easily
using the relatively inexpensive hydraulic switch (without using
the oil pressure sensor for detecting the value of an oil pressure).
In addition, in many cases, the hydraulic switch is provided on
the hydraulic device such as the change-speed control valve of the
automatic transmission, and in such a case, the detection of abnormalities
can be implemented using the hydraulic switch easily without selecting
any specific place for the detection. Furthermore, abnormalities
of the hydraulic switch can be detected easily by obtaining the
signal oil pressure when the engagement or release of the frictional
engagement element is started.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 is a block diagram showing the configuration of an
abnormalities detection apparatus according to the invention;
[0022] FIG. 2 is a sectional view showing the construction of an
automatic transmission which is a subject to be detected by the
abnormalities detection apparatus;
[0023] FIG. 3 is a sectional view showing the construction of the
automatic transmission;
[0024] FIGS. 4A and 4B are schematic views showing power transmission
path construction of the automatic transmission;
[0025] FIG. 5 is a schematic side view showing a physical relationship
of axes of the automatic transmission;
[0026] FIGS. 6A and 6B are graphs showing characteristics of a
linear solenoid valve which is detected with respect to abnormalities
thereof in accordance with the invention;
[0027] FIG. 7 is a flowchart showing the details of abnormalities
detection according to the invention;
[0028] FIG. 8 is a table explaining the details of abnormalities
detection according to the invention;
[0029] FIG. 9 is a flowchart showing the details (the details in
step S10 in the flowchart shown in FIG. 7) of abnormalities detection
according to the invention;
[0030] FIG. 10 is a flowchart showing the details (the details
in step S20 in the flowchart shown in FIG. 9) of abnormalities detection
according to the invention;
[0031] FIG. 11 is a graph showing time variations of designated
oil pressure, engine speed, hydraulic switch output signal and transmission
input shaft revolution speed which are described in the flowchart
shown in FIG. 10; and
[0032] FIG. 12 is a flowchart showing the details (the details
in step S50 in the flowchart shown in FIG. 9) of abnormalities detection
according to the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0033] Referring to the appended drawings, a preferred embodiment
of the invention will be described below. Firstly, referring to
FIGS. 2 to 5, an automatic transmission will be described to which
an apparatus and a method for detecting abnormalities according
to the invention is applied. This transmission includes a torque
converter TC connected to an engine output shaft (not shown), a
parallel axes type transmission mechanism TM connected to an output
member (a turbine) of the torque converter TC and a differential
mechanism DF having a final reduction driven gear 6b which meshes
with a final reduction drive gear 6a of the transmission mechanism
TM, whereby drive force is transmitted to left and right wheels
from the differential mechanism DF. All of the above transmission
constituent components are disposed within a transmission housing
HSG.
[0034] The parallel axes type transmission mechanism TM is constructed
to have a first input shaft 1, a second input shaft 2, a countershaft
3 and an idler shaft 5 which extend in parallel with one another.
Axial centers of the respective shafts are disposed at positions
indicated as S1, S2, S3 and S5 in FIG. 5. The power transmission
structure of this parallel axes type transmission mechanism TM is
shown in FIGS. 4A and 4B, in which FIG. 4A shows a sectional view
passing through the first input shaft 1 (S1), the countershaft 3
(S3) and the second input shaft 2 (S2) along the line IIIA-IIIA
shown in FIG. 5 and FIG. 4B shows a sectional view passing through
the first input shaft 1 (S1) the idler shaft 5 (5) and the second
input shaft 2 (S2) along the line IIIB-IIIB shown in FIG. 5. In
addition, FIG. 2 is a sectional view of the transmission mechanism
TM corresponding to FIG. 4A and FIG. 3 is a sectional view of the
transmission 5 mechanism TM corresponding to FIG. 4B.
[0035] The first input shaft 1 is connected to a turbine of the
torque converter TC and is rotatably supported by bearings 41a,
41b. The first input shaft 1 receives drive force from the turbine
and rotates together with the turbine. Disposed on the first input
shaft 1 sequentially from the torque converter side (the right-hand
side as viewed in-the figures) are a fifth drive gear 25a, a fifth
clutch 15, a fourth clutch 14, a fourth drive gear 24a, a reverse
drive gear 26a and a first connecting gear 31. The fifth drive gear
25a is disposed rotatably on the first input shaft 1 and is engaged
with and disengaged from the first input shaft 1 by the fifth clutch
15 which is actuated by virtue of oil pressure force. In addition,
the fourth drive gear 24a and the reverse drive gear 26a are connected
to each other integrally and are disposed rotatably on the first
input shaft 1, whereby the gears are engaged with and disengaged
from the first input shaft 1 by the fourth clutch 14 which is actuated
by virtue of oil pressure force. The first connecting gear 31 is
located outwardly of the bearing 41a which rotatably supports the
first input shaft 1 and is connected to the first input shaft 1
in a cantilever fashion.
[0036] The second input shaft 2 is rotatably supported by bearings
42a, 42b, and disposed on this shaft sequentially from the right-hand
as viewed in the figures are a second clutch 12, a second drive
gear 22a, a LOW drive gear 21a, a LOW clutch 11, a third clutch
13, a third drive gear 23a and a fourth connecting gear 34. The
second drive gear 22a, the LOW drive gear 21a and the third drive
gear 23a are rotatably disposed on the second input shaft 2 and
are engaged with and disengaged from the second input shaft 2 by
the second clutch 12, the LOW clutch 11 and the third clutch 13,
respectively, which are actuated by virtue of oil pressure force.
The fourthconnectinggear34 is connected to the second input shaft
2.
[0037] The idler shaft 5 is rotatably supported by bearings 45a,
45b, and provided integrally on this shaft are a second connecting
gear 32 and a third connecting gear 33. The second connecting gear
32 meshes with the first connecting gear 31, and the third connecting
gear 33 meshes with the fourth connecting gear 34. A connecting
gear train 30 are constituted by these first to fourth connecting
gears, and the rotation of the first input shaft 1 is normally transmitted
to the second input shaft 2 via the connecting gear train 30.
[0038] The countershaft 3 is rotatably supported by bearings 43a,
43b, and disposed on this shaft sequentially from the right-hand
as viewed in the figures are a final reduction drive gear 6a, a
second driven gear 22b, a LOW driven gear 21b, a fifth driven gear
25b, a third driven gear 23b, a fourth driven gear 24b, a dog clutch
16 and a reverse driven gear 26c. The final reduction drive gear
6a, the second driven gear 22b, the LOW driven gear 21b, the fifth
driven gear 25b and the third driven gear 23b are connected to the
countershaft 3 and rotate together therewith The fourth driven gear
24b is rotatably disposed on the countershaft 3. In addition, the
reverse driven gear 26c is also rotatably disposed on the countershaft
3. The dog clutch 16 is actuated in axial directions so that the
fourth driven gear 24b and the reverse driven gear 24b are engaged
with and disengaged from the countershaft 3, respectively.
[0039] In addition, as shown in the figures, the LOW drive gear
21a meshes with the LOW driven gear 21b, the second drive gear 22a
with the second driven gear 22b, the third drive gear 23a with the
third driven gear 23b, the fourth drive gear 24a with the fourth
driven gear 24b and the fifth drive gear 25a with the fifth driven
gear 25b. Furthermore, the reverse drive gear 26a meshes with the
reverse driven gear 26c via a reverse idler gear 26b (refer to FIG.
3).
[0040] While not shown in the figures, the final reduction drive
gear 6a meshes with the final driven gear 6b (refer to FIG. 2),
and the rotation of the countershaft 3 is transmitted to the differential
mechanism DF via these final reduction drive and driven gears 6a,
6b.
[0041] In the transmission constructed as described above, setting
of the respective gears and power transmission paths thereof will
be described. In addition, in this transmission, in a forward range,
the dog clutch 16 is moved to the right as viewed in the figures,
whereby the fourth driven gear 24b is brought into engagement with
the countershaft 3. In a reverse range, the dog clutch 16 is moved
to the left, so that the reverse driven gear 26c is brought into
engagement with the countershaft 3.
[0042] Firstly, the respective gears in the forward range will
be described. The LOW gear is set through the engagement of the
LOW clutch 11. Rotational driving force transmitted from the torque
converter TC to the first input shaft 1 is transmitted to the second
input shaft 2 via the connecting gear train 30. Here, since the
LOW clutch 11 is in engagement therewith, the LOW drive gear 21a
rotates together with the second input shaft 2, and the LOW driven
gear 21b meshing with the LOW drive gear is then driven to rotate,
the countershaft 3 being driven. The driving force is then transmitted
to the differential mechanism DF via the final reduction gear train
6a, 6b.
[0043] The second gear is set through the engagement of the second
clutch 12. Rotational driving force transmitted to the first input
shaft 1 from the torque converter TC is transmitted to the second
input shaft 2 via the connecting gear train 30. Here, since the
second clutch 12 is in engagement therewith, the second drive gear
22a rotates together with the second input shaft 2, and the second
driven gear 22b meshing with the second drive gear is driven to
rotate, whereby the countershaft 3 is driven. The driving force
is transmitted to the differential mechanism DF via the final reduction
gear train 6a, 6b.
[0044] The third gear is set through engagement of the third clutch
13. Rotational driving force transmitted to the first input shaft
1 from the torque converter TC is transmitted to the second input
shaft 2 via the connecting gear train 30. Here, since the third
clutch 13 is in engagement therewith, the third drive gear 23a rotates
together with the second input shaft 2, and the third driven gear
23b meshing with the third drive gear 23a is driven to rotate, whereby
the countershaft 3 is driven. The driving force is transmitted to
the differential mechanism DF via the final reduction gear train
6a, 6b.
[0045] The fourth gear is set through engagement of the fourth
clutch 14. Rotational driving force transmitted to the first input
shaft 1 from the torque converter TC drives to rotate the fourth
drive gear 24a via the fourth clutch 14, and the fourth driven gear
24b meshing with the-fourth drive gear is driven to rotate. Here
in the forward range, since the fourth driven gear 24b is engaged
with the countershaft 3 by the dog clutch 16, the countershaft 3
is driven, and the driving force is then transmitted to the differential
mechanism DF via the final reduction gear train 6a, 6b.
[0046] The fifth gear is set through engagement of the fifth clutch
15. Rotational driving force transmitted to the first input shaft
1 from the torque converter TC drives to rotate the fifth drive
gear 25a via the fifth clutch 15, and the fifth driven gear 25b
meshing with the fifth drive gear 25a is driven to rotate. Since
the fifth driven gear 25b is connected to the countershaft 3, the
countershaft 3 is driven, and the driving force is then transmitted
to the differential mechanism DF via the final reduction gear train
6a, 6b.
[0047] The reverse gear is set through engagement of the fourth
clutch and movement of the dog clutch 16 to the left. Rotational
driving force transmitted to the first input shaft 1 from the torque
converter TC rotates the reverse drive gear 26a via the fourth clutch
14, and the reverse driven gear 26c meshing with the reverse drive
gear 26a via the reverse idler gear 26b is driven to rotate. Here,
in the reverse range, since the reverse driven gear 26c is engaged
with the countershaft 3 by the dog clutch 16, the driving force
is transmitted to the differential mechanism DF via the final reduction
gear train 6a, 6b. As is seen from this, the fourth clutch 14 also
functions as a reverse clutch.
[0048] In the automatic transmission constructed as described above,
as is seen from the description made heretofore, the respective
forward gears can be set by actuating the dog clutch 16 to engage
with the LOW clutch 11, the second clutch 12, the third clutch 13,
the fourth clutch 14 and the fifth clutch 15, whereby an automatic
transmission control can be implemented by controlling the above
engagements based on the vehicle speed and the engine throttle opening.
[0049] Referring to FIG. 1, the construction of an apparatus for
performing the automatic transmission control will be described
below. An automatic transmission control unit TCU includes a transmission
control valve 50, first to third linear solenoid valves 51 to 53,
a group of circuit switching solenoid valves 55 and an electronic
control unit 60. The transmission control valve 50 controls the
supply of engagement control oil pressure to the LOW clutch 11,
the second clutch 12, the third clutch 13, the fourth clutch 14,
the fifth clutch 15 and the like (in addition thereto, there is
a servo cylinder for actuating the dog clutch 16). The first to
third linear solenoid valves 51 to 53 set engagement control oil
pressures that are supplied to the respective clutches. The group
of circuit switching solenoid valves 55 includes a plurality of
ON/OFF solenoid valves for controlling the actuation of shift valves
constituting the transmission control valve 50. The electronic control
unit 60 sends control signals to the first to third linear solenoid
valves 51 to 53 and the group of circuit switching solenoid valves
55 for controlling the actuation thereof.
[0050] A first hydraulic switch 61 and a second hydraulic switch
62 are provided in the transmission control valve 50. The first
hydraulic switch 61 is adapted to be switched on and off upon receipt
of engagement control oil pressure that is supplied to the second
clutch 12. The second hydraulic switch 62 is adapted to be switched
on and off upon receipt of engagement control oil pressure that
is supplied to the third clutch 13. ON/OFF signals from these first
and second hydraulic switches 61, 62 are inputted into the electronic
control unit 60. In addition, an engine speed signal Ne detected
by the engine speed sensor 65 for detecting the engine speed is
also inputted into the electronic control unit 60. Note that while
additional various signals (for example, engine throttle opening
signal, vehicle speed signal, brake apply signal and the like) are
also inputted into the electronic control unit 60, the illustration
thereof is omitted herein.
[0051] Upon receipt of various signals which are inputted thereinto
as described above, the electronic control unit 60 selects a gear
suitable for then running conditions in response to the vehicle
speed and the engine throttle opening, controls the actuation of
the transmission control valve 50 so as to set the selected gear
and selectively supply engagement control oil pressures to the LOW
clutch 11, the second clutch 12, the third clutch 13, the fourth
clutch, and the fifth clutch 15. As this occurs, the control of
the actuation of the first to third linear solenoid valves 51 to
53 is carried out at the same time, whereby the control of engagement
control oil pressures is implemented, a smooth transmission control
being thereby effected.
[0052] In the transmission control unit TCU constructed as described
above, the first to third linear solenoid valves 51 to 53 are such
that control engagement control oil pressures in response to control
signals (control electric current) sent from the electronic control
unit 60 and have, for example, characteristics shown in FIG. 6A.
Namely, as shown in the figure, the electronic control unit 60 has
characteristics that as a control signal (control electric current)
sent to the linear solenoid valves 51 to 53 increases, a control
oil pressure to be controlled thereby becomes higher. In addition,
in FIG. 6A, a solid line P indicates the variation characteristics
of a control oil pressure when the control signal is increased gradually
from zero, and a broken line Q indicates the variation characteristics
of a control oil pressure when the control signal is decreased gradually.
[0053] As long as the linear solenoid valve functions properly,
as shown in FIG. 6A, the solenoid valve exhibits substantially the
same characteristics both when the control signal is increased (the
solid line P) and when the control signal is decreased (the broken
line Q). However, in the event that the linear solenoid valve becomes
abnormal, as shown in FIG. 6B, the linear solenoid valve may come
to exhibit different characteristics between when the control signal
is increased (a solid line P) and when the control signal is decreased
(a broken line Q). Since there is caused a problem that the transmission
control becomes imprecise in case the linear solenoid valve having
such characteristics is used to regulate the engagement oil pressure,
the apparatus of the invention is designed such that abnormalities
of the linear solenoid valve are detected.
[0054] Apparatus and method for detecting abnormalities constructed
as described above will be described below. As shown in FIG. 1,
this detection of abnormalities is carried out based on an abnormalities
diagnosis program from an external diagnosis unit 70 by connecting
the external diagnosis unit 70 to the electronic control unit 60.
In addition, in this embodiment, while an example will be described
in which the external diagnosis unit 70 is connected to the electronic
control unit 60 for detecting abnormalities, the abnormalities diagnosis
program may be incorporated in the electronic control unit 60 and
abnormalities detection may be performed as required based on the
incorporated program without using the external diagnosis unit 70.
[0055] This external diagnosis unit 70 is adapted to detect abnormalities
of the first to third linear solenoid valves 51 to 53, as well as
various types of abnormalities of the transmission control unit,
and the detection of abnormalities will be described below. The
detection of abnormalities is carried out individually for each
of the first to third linear solenoid valves 51 to 53. Owing to
this, firstly, the actuation of the group of circuit switching solenoid
valves 55 is controlled from the external diagnosis unit 70 via
the electronic control unit 60, and any of the linear solenoid valve
is caused to communicate with the second clutch-12 on which the
first hydraulic switch 61 is provided or the third clutch 13 on
which the second hydraulic switch 62 is provided. Then, an engagement
control oil pressure that has been regulated by any of the linear
solenoid valves that provides such a communication is supplied to
the clutch with which the linear solenoid valve is allowed to communicate
for detecting the actuation of the hydraulic switch provided therein
so as to implement the determination of abnormalities.
[0056] Here, while the group of circuit switching solenoid valves
55 are aimed to set engagement control oil pressure supply paths
to the respective clutches via the transmission control valve 50,
in control, a pattern in which an engagement control oil pressure
regulated by the first or second linear solenoid valve 51, 52 is
supplied to the second clutch 12 and a pattern in which an engagement
control oil pressure regulated by the third linear solenoid valve
53 is supplied to the third clutch 13 are set according to speed
change conditions. Owing to this, the detection of abnormalities
of the first linear solenoid valve 51 is implemented by allowing
the same valve to communicate with the second clutch 12, the detection
of abnormalities of the second linear solenoid valve 52 is implemented
by allowing the same valve to the second clutch 12, too, and the
detection of abnormalities of the third linear solenoid valve 53
is implemented by allowing the same valve to communicate with the
third clutch 13.
[0057] The detection of abnormalities will be described below with
reference to an example in which the first linear solenoid valve
51 is allowed to communicate with the second clutch 12. Note that
since the detection of abnormalities of the second and third linear
solenoid valves 52, 53 can be implemented in a similar manner, the
description thereof will be omitted herein. The details of the detection
of abnormalities are shown in FIG. 7, and first of all, whether
or not the vehicle is at rest (step S1), whether or not the brakes
of the vehicle are being applied (step S2) and whether or not the
engine is at idle (step S3) are determined, and an abnormalities
detection is carried out only when the vehicle is at rest, the brakes
of the vehicle are being applied and the engine is at idle.
[0058] This abnormalities detection has an abnormalities detection
(step S5) to be performed in a state in which a control signal (a
control signal representing a designated oil pressure=0) is outputted
to the first linear solenoid valve 51 to make the engagement control
oil pressure zero, an abnormalities detection (step S7) to be performed
in a state in which a control signal (a control signal representing
a designated oil pressure=upper limit) is outputted to the first
linear solenoid 51 to make the engagement control oil pressure the
upper limit and an abnormalities detection (step S10) to be performed
while outputting a control signal to vary the engagement control
oil pressure that is regulated by the first linear solenoid valve
51.
[0059] Referring to FIG. 8, the contents of the abnormalities detections
to be performed in steps S5 and S7 will be described. Firstly, the
abnormalities detection to be performed in step S5 with the designated
oil pressure=0 will be described. This abnormalities detection is
carried out by detecting the ON/OFF state of the first hydraulic
switch 61 and the engagement state of the second clutch 12. The
first hydraulic switch 61 is a switch adapted to be switched on
upon receipt of an oil pressure which is equal to or greater than
a switching oil pressure required to start the engagement of the
second clutch 12 and is in an OFF state when the switch is receiving
an oil pressure which is less than the switching oil pressure. In
addition, the engagement of the second clutch 12 is determined based
on whether or not the rotating speed NM of a transmission input
shaft (the first input shaft 1 or the second input shaft 2) is rotated
according to the engine idling speed and whether or not the second
clutch 12 is put into engagement with the vehicle being at rest
to stop the rotation of the output shaft of the torque converter
TC, whereby the torque converter TC is put in a stall state to be
stopped.
[0060] Note that while in this embodiment the engagement of the
second clutch 12 is determined from the revolution speed NM of the
input shaft, another method may be used to determine the engagement
of the second clutch 12. For example, the engagement of the second
clutch 12 may be determined based on a difference between input
and output revolution speeds of the second clutch 12 or difference
between input and output revolution ratios. And, the engagement
may be determined based on the change of the engine speed NE. In
addition, as shown in FIG. 11, the engine speed NE becomes a non-loaded
idling speed NE0 when the clutch is released, whereas when the clutch
is engaged the torque converter TC stalls and the engine speed decreases
to a stall idling speed NE1.
[0061] As shown in FIG. 8, it is considered that a state in which
the second clutch 12 becomes released with the designated oil pressure=0
and the first hydraulic switch 61 switched on (this is when the
revolution speed NM of the transmission input shaft corresponds
to the engine speed, and this is referred to as an off-gear state)
is a state in which the first hydraulic switch 61 is put in a ON
state with the engagement control oil pressure of the second clutch
12 which is regulated by and supplied from the first linear solenoid
valve 51 being substantially zero, and this state can be determined
as an abnormality that the first hydraulic switch 61 is kept switched
on. On the other hand, it is considered that a state in which the
first hydraulic switch 61 is on with the second clutch 12 being
in engagement (this is when a transmission input shaft revolution
speed NM=0, and this is referred to as an in-gear state) is a state
in which an oil pressure is supplied from the first linear solenoid
valve 51 to bring the second clutch 12 into engagement while the
designated oil pressure=0, and this can be determined as an abnormality
that the first linear solenoid valve 51 sticks to the ON side (a
side where the oil pressure is generated).
[0062] Next, when the first hydraulic switch 61 is off, in case
the second clutch 12 is in the off-gear state, the linear solenoid
valve is normal. However, in case the second clutch 12 is in the
in-gear state, it is considered as a state in which the second clutch
12 is in an engaged state while the engagement control oil pressure
is substantially zero or a state in which there is a failure of
an engagement detection of the second clutch 12, and therefore this
can be determined as an abnormality that the second clutch 12 sticks
to be in the engaged state, an abnormality of an engagement control
valve system of the second clutch 12 or an abnormality of the engine
speed sensor 65.
[0063] Next, an abnormalities detection that is performed in step
S7 with the designated oil pressure=upper limit will be described.
This abnormalities detection is also implemented through detection
of the on/off state of the first hydraulic switch 61 and the engagement
of the second clutch 12. Firstly, when the first hydraulic switch
61 is switched on, in case the second clutch 12 is in the in-gear
state, it is normal. However, in case the second clutch 12 is in
the off-gear state, it is considered as a state in which a predetermined
engagement control oil pressure is being outputted while the second
clutch 12 is being released or a state in which there exists a failure
of detection of the engagement of the second clutch 12, and this
can be determined as an abnormality of the second clutch 12 itself
or the engine speed sensor 65.
[0064] On the other hand, when the first hydraulic switch 61 is
off whereas the second clutch 12 is in the off-gear state, it is
considered that the engagement control oil pressure supplied from
the first linear solenoid valve 51 to the second clutch 12 is substantially
zero, it can be determined that there exists an abnormality that
the first linear solenoid valve 51 sticks to the off side (a side
where no oil pressure is outputted) On the contrary, when the first
hydraulic switch 61 is off whereas the second clutch is in the in-gear
state, it is considered that the first hydraulic switch 61 cannot
be detected whereas an engagement control oil pressure sufficient
to bring the second clutch 12 into engagement is supplied from the
first linear solenoid valve 51 to the second clutch 12, and it can
be determined that there exists an abnormality that the first hydraulic
switch 61 is put in the off state.
[0065] When the abnormalities detections in step S5 and step S7
have been completed as described above, then an abnormalities detection
carried out while varying the designated oil pressure in step S10
is carried out. The basic structure of this abnormalities detection
is shown in FIG. 9. A pressure-increased side signal oil pressure
is detected while varying gradually the designated oil pressure
from zero (a predetermined lower pressure) to a maximum (a predetermined
higher pressure), and then a pressure-decreased side signal oil
pressure is detected while varying gradually the designated oil
pressure from the maximum (the predetermined higher pressure) to
zero (the predetermined lower pressure) (step S30), following this,
an abnormalities determination is implemented based on these detected
signal oil pressures (step S50).
[0066] Firstly, referring to FIG. 10, the contents of a detection
in step S20 will be described. Here, firstly, it is determined whether
or not a pressure increase completion flag F(UP) which is set when
the designated oil-pressure has been gradually increased to an upper
limit is 1, F(UP)=1, namely, whether or not the flag is set (step
S22). When F(UP)=0, the flow proceeds to step S23, where a designated
oil pressure PI (an oil pressure to cause the linear solenoid valve
to implement regulation and setting based on a control signal) which
is designated by a control signal is increased by a predetermined
amount .DELTA.P.
[0067] Then, it is determined whether or not a first switch flag
FPS1 which is set when the first hydraulic switch 61 is switched
off from on is 1, FPS1=1 (step S24), and when the flag is set (when
FPS1=1), the flow proceeds to step S27. On the other hand, when
FPS1=0, then the flow proceeds to step S25, where it is determined
whether or not the first hydraulic switch 61 is switched on. Then,
when it is determined that the switch has been switched on, the
then designated oil pressure PI is stored as a first pressure-increased
side signal oil pressure PUP1, and 1 is set on the first switch
flag FPS1 (step S26).
[0068] Next, in step S27, it is determined whether or not an engagement
flag FNM1 which is set when the second clutch 12 is brought into
engagement is 1, FNM1=1, and when this flag is set then the flow
proceeds to step S30. On the other hand, when FNM1=0, the flow proceeds
to step S28, and it is determined whether or not the transmission
input shaft rotation NM has become zero, namely, whether or the
second clutch 12 has started engagement. When this variation is
detected, the then designated oil pressure PI is stored as a second
pressure-increased side signal oil pressure PUP2, and the engagement
flag FNM1 is set to 1 (step S29). Then, in step S30, it is determined
whether or not the designated oil pressure PI has reached the upper
limit (MAX), and when the pressure has reached the upper limit the
pressure increase completion flag F(UP) is set to 1. (step S31).
[0069] The flow of steps S22 to S31 that has just been described
is repeatedly performed at predetermined intervals, the designated
oil pressure PI is increased gradually to the upper limit (MAX)
(or the pressure is increased by .DELTA.P at each predetermined
interval). As a result, in case the first linear solenoid valve
51 functions properly, working fluid regulated to the designated
oil pressure PI is supplied to the second clutch 12. FIG. 11 shows
time variation of the designated oil pressure PI, time variation
of the engine speed NE, on/off signal variation of the first hydraulic
switch 51 and time variation of the transmission input shaft revolution
speed NM. The designated oil pressure PI is zero at time t, and
this pressure increases in a certain proportion and reaches the
upper limit at time t2. Owing to this, the pressure increase completion
flag F(UP) is set to 1 at time t2.
[0070] When the designated oil pressure PI is increased like this
the oil pressure which has been regulated and supplied in conjunction
with the increase acts on the second clutch 12 and the first hydraulic
switch 61. In this example, it is detected that the transmission
input shaft revolution speed NM became zero at time t1 and that
the second clutch 12 started engagement at the same time. Owing
to this, the then designated oil pressure PI (a designated oil pressure
at point A) was stored as a second pressure-increased side signal-oil
pressure PUP2, and the engagement flag FNM1 was set to 1. Furthermore,
the first hydraulic switch 61 was switched on from off at time t11.
Owing to this, the then designated oil pressure PI (a designated
oil pressure at point C) was stored as the first pressure-increased
side signal oil pressure PUP1, and the first switch flag FPS1 was
set to 1. Thereafter, when the designated oil pressure PI reaches
the upper limit at time t2, the pressure increase completion flag
F(UP) is set to 1.
[0071] When the pressure increase completion flag F(UP)=1, in FIG.
10, the flow proceeds from step S22 to S35, where it is determined
whether or not a pressure decrease completion flag F(DN) which is
set when the designated oil pressure that has reached the upper
limit is decreased gradually to zero is 1, F(DN)=1, namely, whether
or not the flag is set. When F(DN)=0, then the flow proceeds to
step S36, where the designated oil pressure PI which has been increased
to the upper limit is then decreased by the predetermined amount
.DELTA.P.
[0072] Then, it is determined whether or not a second switch flag
FPS2 which is set when the first hydraulic switch 61 is switched
off from on is 1, FPS2=1 (step S37), and when this flag is set (FPS2=1)
the flow proceeds to step S40. On the other hand, when FPS2=0, the
flow proceeds to step S38, where it is determined whether or not
the first hydraulic switch 61 has been switched off. Then, when
it is determined that the switch has been switched off the then
designated oil pressure PI is stored as a first pressure-decreased
side signal oil pressure PDN1, and 1 is set on the second switch
flag FPS2 (step S39).
[0073] Next, in step S40, it is determined whether or not a release
flag FNM2 that is set when the release of the second clutch 12 has
is detected is 1, FNM2=1, and when this flag is set, the flow proceeds
to step S41. On the other hand, when FNM2=0, the flow proceeds to
step S41, it is determined whether or not the transmission input
shaft revolution speed NM has been varied from zero to an idling-corresponding
revolution speed, namely, whether or not the second clutch 12 has
started to be released. When this variation has been detected the
then designated oil pressure PI is stored as a second pressure-decreased
side signal oil pressure PDN2, and the release flag FNM2 is set
to 1 (step S42). Then, in step S43, it is determined whether or
not the designated oil pressure PI has become zero, and when the
pressure has become zero, the pressure decrease completion flag
F(DN) is set to 1.
[0074] The flow of steps S22 to S35 to S44 that has been just described
is repeated performed at predetermined intervals, the designated
oil pressure PI is decreased gradually from the upper limit (MAX)
to zero (namely, decreased by .DELTA.P at each predetermined interval).
As a result, as shown in FIG. 11, the designated oil pressure PI
that has reached the upper limit is decreased in a certain proportion
and becomes zero at time t4, and the pressure decrease completion
flag F(DN) is set to 1.
[0075] When the designated oil pressure PI is decreased in this
way, in this example, the first hydraulic switch 61 was switched
off from on at time t12. Owing to this, the then designated oil
pressure PI (a designated oil pressure at point D) was stored as
the first pressure-decreased side signal oil pressure PDN1, and
a second switch flag FPS2 was set to 1. Furthermore, that the second
clutch 12 has started to be released was detected at time t3. Owing
to this, the then designated oil pressure PI (a designated oil pressure
at point B) was stored as the second pressure-decreased side signal
oil pressure PDN2, and the release flag NM2 was set to 1. Thereafter,
when the designated oil pressure PI became zero at time t4, the
pressure decrease completion flag F (DN) was set to 1 and the control
flow proceeds from step S35 to step S48, where the detection is
determined as having been completed, and a reset operation is performed.
[0076] When the flow in step S20 is completed a flow in step S50
shown in FIG. 12 is performed. Here, in step S51, an absolute value
DP (this is referred to as a first signal oil pressure difference
DP) is calculated which is a difference between the first pressure-increased
side signal oil pressure PUP1 and the first pressure-decreased side
signal oil pressure PDN1. Then, it is determined whether or not
this first signal oil pressure difference DP is equal to or larger
than a first abnormalities determination value .alpha.1 (step S52),
and when DP.gtoreq..alpha.1, it is determined that the first linear
solenoid valve is abnormal (step S53).
[0077] The first pressure-increased side signal oil pressure PUP1
is a designated oil pressure when the first hydraulic switch 61
is switched on from off when the engagement control oil pressure
that is supplied to the second clutch 12 becomes equal to or larger
than the switching oil-pressure, while the first pressure-decreased
side signal oil pressure PDN1 is a designated oil pressure when
the first hydraulic switch 61 is switched on from off when the engagement
control oil pressure that is supplied to the second clutch 12 in
the engaged state becomes less than the switching oil pressure,
and basically both the signal pressures PUP1, PDN1 must be values
which are equal or closer to each other. Owing to this, when the
first signal oil pressure difference DP which is the difference
between the two signal oil pressures is increased to be far larger
than the first abnormalities determination value .alpha.1, the resultant
state becomes a state shown in FIG. 6B, and it is determined that
the first linear solenoid valve 51 is abnormal.
[0078] Next, in step S54, an absolute value DPUP (this is referred
to as a second signal oil pressure difference DUPU) is calculated
which is a difference between the first pressure-increased side
signal oil pressure PUP1 and the second pressure-increased side
signal oil pressure PUP2. Then, it is determined whether or not
the second signal oil pressure difference DUPU is equal to or larger
than a second abnormalities determination value .alpha.2 (step S55),
and when DP.gtoreq..alpha.2, it is determined that the first hydraulic
switch 61 is abnormal (step S56).
[0079] The first pressure-increased side signal oil pressure PUP1
is a designated oil pressure when the first hydraulic switch 61
is switched on from off when the engagement control oil pressure
that is supplied to the second clutch 12 becomes equal to or larger
than the switching oil pressure, while the second pressure-increased
side signal oil pressure PUP2 is a designated oil pressure when
the second clutch 12 actually starts to be engaged. Here, the switching
oil pressure is set to become the engagement initiation oil pressure
of the second clutch 12, and basically both the signal oil pressures
have to be values which are equal or closer to each other. Owing
to this, when the second signal oil pressure difference DPUP which
is the difference between the two signal oil pressures is increased
to be far larger than the second abnormalities determination value
.alpha.2, it is determined that the first hydraulic switch 61 is
abnormal.
[0080] Next, in step S57, an absolute value DPDN (this is referred
to as a third signal oil pressure difference DPDN) is calculated
which is a difference between the first pressure-decreased side
signal oil pressure PDN1 and the second pressure-decreased side
signal oil pressure PDN2. Then, it is determined whether or not
the third signal oil pressure difference DPDN is equal to or larger
than a third abnormalities determination value .alpha.3 (step S58),
and when DP.gtoreq..alpha.3, it is determined that the first hydraulic
switch 61 is abnormal (step S59).
[0081] The first pressure-decreased side signal oil pressure PDN1
is a designated oil pressure when the first hydraulic switch 61
is switched off from on when the engagement control oil pressure
that is supplied to the second clutch 12 becomes less than the switching
oil pressure, while the second pressure-decreased side signal oil
pressure PDN2 is a designated oil pressure when the second clutch
12 actually starts to be released. Owing to this, when the third
signal oil pressure difference DPDN which is the difference between
the two signal oil pressures is increased to be far larger than
the third abnormalities determination value .alpha.3, it is determined
that the first hydraulic switch 61 is abnormal.
[0082] In addition, the determination in steps S54 to S56 and the
determination in step S57 to S59 are both aimed to determine abnormalities
of the first hydraulic switch, and either of the determinations
may be performed.
[0083] In the above embodiment, while the example has been described
in which the clutch engagement oil pressure control of the transmission
is implemented by the linear solenoid valves, the application of
the oil pressure regulated by the linear solenoid valve is not limited
thereto, and the invention may be applied to various types of hydraulic
devices adapted to be actuated upon receipt of oil pressure force.
[0084] As has been described heretofore, according to the apparatus
and method for detecting abnormalities of the linear solenoid valve
according to the invention, it is constructed that the linear solenoid
valve is diagnosed as being abnormal when the difference between
the pressure-increased side signal oil pressure and the pressure-decreased
side signal oil pressure which are both signal pressures when the
hydraulic switch is switched on and off exceeds the abnormalities
determination value, and the existence of abnormalities of the linear
solenoid valve can be detected easily using the relatively inexpensive
hydraulic switch (without using the oil pressure sensor for detecting
the value of an oil pressure).
[0085] According to the further apparatus and method for detecting
abnormalities of the hydraulic device according to the invention,
the engagement control oil pressure that is supplied to the frictional
engagement element is designed to be regulated by the linear solenoid
valve, and the regulated engagement control oil pressure is designed
to act on the hydraulic switch which is switched on and off at the
engagement control oil pressure, as the switching oil pressure,
at which the frictional engagement element starts to be engaged,
whereby the linear solenoid valve is determined as being abnormal
when the difference between the first pressure-increased side signal
oil pressure and the first pressure-decreased side signal oil pressure
exceeds the first abnormalities determination value. In this case,
too, the abnormalities of the linear solenoid valve can be detected
easily using the relatively inexpensive hydraulic switch (without
using the oil pressure sensor for detecting the value of an oil
pressure) In addition, in many cases, the hydraulic switch is provided
in the hydraulic device such as the transmission control valve of
the automatic transmission, and in this case, the abnormalities
detection can be implemented easily anytime using the hydraulic
switch without selecting any specific place for detection.
[0086] The apparatus for detecting abnormalities is provided with
an engagement detection unit (for example, the electronic control
unit 60 adapted to be actuated upon receipt of a detection signal
from an engine speed sensor 65 in the embodiment) for detecting
an engagement of the frictional engagement element, wherein a control
signal is sent from the valve actuating controller to the linear
solenoid valve to increase the engagement control oil pressure from
the predetermined lower pressure to the predetermined higher pressure
to thereby cause the linear solenoid valve to regulate the frictional
engagement control oil pressure, during which a second pressure-increased
side signal oil pressure resulting when the engagement of the frictional
engagement element is started is detected by the engagement detection
unit, whereby the hydraulic switch may be diagnosed as being abnormal
when a difference between the first pressure-increased side signal
oil pressure and the second pressure-increased side signal oil pressure
exceeds a second abnormality determination value.
[0087] The apparatus for detecting abnormalities is provided with
an engagement detection unit for detecting an engagement of the
frictional engagement element, wherein a control signal is sent
from the valve actuating controller to the linear solenoid valve
to decrease the engagement control oil pressure from the predetermined
higher pressure to the predetermined lower pressure to thereby cause
the linear solenoid valve to regulate the frictional engagement
control oil pressure, during which a second pressure-decreased side
signal oil pressure resulting when the release of the frictional
engagement element is started is detected by the engagement detection
unit, whereby the hydraulic switch is diagnosed as being abnormal
when a difference between the first pressure-decreased side signal
oil pressure and the second pressure-decreased side signal oil pressure
exceeds a third abnormality determination value.
[0088] The hydraulic switch is set to use as the switching oil
pressure the engagement control oil pressure at which the engagement
of the frictional engagement element is started, and as described
above, in the event that the difference between the first pressure-increased
side signal oil pressure and the second pressure-increased side
signal oil pressure exceeds the second abnormality determination
value, or in the event that the difference between the first pressure-decreased
side signal oil pressure and the second pressure-decreased side
signal oil pressure exceeds the third abnormality determination
value, it is considered that an abnormality is being caused such
as the set switching oil pressure at which the hydraulic switch
is switched on and off is deviated or the hydraulic switch fails
to operate properly. Then, according to the invention, abnormalities
of the hydraulic switch can also be detected based on the above
determination.
[0089] In addition, in the invention, in the event that the frictional
engagement element is used as a clutch for a transmission for controlling
speed changes of a vehicle or as a brake, the detection of engagement
of the frictional engagement element by the engagement detection
unit is implemented with the vehicle being at halt, the brakes of
the vehicle being applied and an engine of the vehicle being in
an idle state. Furthermore, in a construction in which a torque
converter is disposed at an input portion of the transmission in
such a manner as to be connected to an output shaft of the engine
and in which a transmission mechanism whose actuation is controlled
by the frictional engagement element is provided in such a manner
as to be connected to an output side of the torque converter, it
is preferable that abnormalities are detected with the abnormality
detecting apparatus according to the invention. |