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Patent Abstract
In a two-way solenoid vale, a small diameter portion of a nozzle
portion is fitted in a small diameter portion receiving part communicating
with an output pressure oil passage and a large diameter portion
is fitted in a large diameter portion receiving part communicating
with a supply pressure oil passage. An opening of a through-hole
formed in the nozzle portion faces the output pressure oil passage
by way of the small diameter portion receiving part, and an inner
end of the through-hole is opened and closed by a plunger and communicates
with a drain port. An orifice port communicating with the through-hole
is opened to the large diameter portion receiving part and communicates
with the supply pressure oil passage. Since the orifice port is
disposed in the solenoid valve, a separate plate for an orifice
is not required, oil passage is simplified and the solenoid valve
can be installed in an optional position. The output pressure characteristics
can be adjusted by merely replacing with a solenoid valve having
an orifice port of a different diameter.
Patent Claims
What is claimed is:
1. A solenoid valve circuit for an automatic transmission developing
a predetermined output pressure by draining working fluid supplied
from a supply pressure oil passage through an orifice, by means
of a two-way solenoid valve; wherein said orifice is defined in
a nozzle portion of said two-way solenoid valve.
2. A solenoid valve circuit for an automatic transmission according
to claim 1, wherein said two-way solenoid valve has a drain port;
and an oil hole capable of communicating with said drain port and
an orifice port being in communication with said oil hole and serving
as said orifice are opened to the nozzle portion; an opening of
said orifice port faces said supply pressure oil passage; and an
opening of said oil hole faces an output pressure oil passage.
3. A solenoid valve circuit for an automatic transmission as claimed
in claim 2, wherein said oil hole is opened on an head of the nozzle
portion; said orifice port is opened to a side of the nozzle portion;
said side of the nozzle portion faces said supply pressure oil passage;
and said head of the nozzle portion faces the output pressure oil
passage.
Patent Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a construction of a solenoid
valve circuit for controlling hydraulic pressure in an automatic
transmission for a vehicle.
[0003] 2. Description of the Prior Art
[0004] An automatic transmission for a vehicle has the combination
of a planetary gear mechanism and a plurality of engaging elements
such as clutch, brake or the like which are actuated by hydraulic
pressure, and the combination of engagement and release of the engaging
elements achieve a plurality of gear positions which respectively
provide predetermined gear ratios.
[0005] The engaging elements are controlled by controlling line
pressure with a shift valve in a control valve unit and by supplying
the line pressure to the respective engaging elements. The shift
valve is switched by hydraulic pressure controlled from a constant
pilot pressure by a solenoid valve which is actuated by a control
signal from a shift control system.
[0006] The control of pilot pressure by the solenoid valve is performed
by controlling drain of a working fluid which has passed through
an orifice by the solenoid valve, as in a hydraulic circuit disclosed
in Japanese Patent Application Laid-open No. 1-199044.
[0007] More specifically, in this hydraulic circuit, line pressure
from a manual valve 50, as shown in FIG. 2, is fed to a forward
clutch F/C through an oil passage 51 and at the same time fed to
a servo apply chamber of a brake B through a shift valve 52 provided
in the middle of the oil passage 51. A control port of the shift
valve 52 is in communication with an oil passage 55 extending from
a pilot pressure valve 54, and an orifice 56 is provided in the
middle of the oil passage 55. Moreover, a drain port 57 is provided
on the downstream side of the orifice 56, that is, on the side of
the shift valve 52, and drain of the working fluid is controlled
by a solenoid valve 58. In many cases, the drain port 57 is provided
in the solenoid valve 58.
[0008] As shown in FIG. 3, the conventional solenoid valve circuit
including the orifice 56 and the solenoid valve 58, as described
above, is arranged such that a separate plate 63 disposed between
an upper body 61 and a lower body 62, which construct the control
valve unit, is provided with a small aperture acting as the orifice
56, through which a working fluid supplied from the pilot pressure
valve to the lower body 62 is guided to the upper body 61, and such
that the solenoid valve 58 is disposed near the orifice 56 of the
upper body 61. Moreover, drain of oil pressure on the side of the
upper body 61 is controlled by the solenoid valve 58 to act as output
pressure.
[0009] In the construction of such a solenoid valve circuit, however,
the separate plate 63 is disposed between the upper body 61 and
the lower body 62 to form the orifice 56, and the upper body 61
and the lower body 62 between which the separate plate 63 is arranged
define oil passages. Therefore, even in case where it is desired
to put together the pilot pressure valve and the solenoid valve
58 or the like into one of the upper body 61 and the lower body
62, the pilot pressure valve and the solenoid valve 58 need to be
arranged opposite each other, having the separate plate 63 between
them, whereby the degree of freedom in positions for mounting these
valves becomes low. For example, if both the pilot pressure valve
and the solenoid valve 58 are placed in the upper body 61, it is
required to form a bypass passage leading from the pilot pressure
valve to the oil passage on the side of the lower body 62.
[0010] Moreover, in case of adjusting the output pressure characteristics,
to change the orifice 56, it is required to dismount the solenoid
valve circuit and replace the separate plate 63, and thus this adjustment
operation is difficult.
SUMMARY OF THE INVENTION
[0011] The present invention has been made in view of the aforementioned
problem, and it is an object to provide a solenoid valve circuit
for an automatic transmission which has a high degree of freedom
in positions for mounting a solenoid valve and other valves and
is capable of easily adjusting the output pressure characteristics.
[0012] According to the first aspect of the present invention,
there is provided a solenoid valve circuit for an automatic transmission
developing a predetermined output pressure by draining working fluid
supplied from a supply pressure oil passage through an orifice,
by means of a two-way solenoid valve, wherein said orifice is defined
in a nozzle portion of said two-way solenoid valve.
[0013] Since the orifice is defined in the nozzle portion of the
two-way solenoid valve, other additional members are particularly
not needed to form the orifice and also the degree of freedom in
the installation position is high. Moreover, the output pressure
characteristics may be adjusted by merely replacing with a two-way
solenoid valve having an orifice of a different size, as a result
of which the adjustment operation is greatly simplified.
[0014] Preferably, the two-way solenoid valve has said nozzle portion
and a drain port; an oil hole capable of communicating with the
drain port and an orifice port being in communication with the oil
hole and serving as the orifice are opened to the nozzle portion;
an opening of the orifice port faces the supply pressure oil passage;
and an opening of the oil hole faces an output pressure oil passage.
[0015] After the working fluid from the supply pressure oil passage
has passed through the orifice port, output pressure is regulated
to a predetermined pressure by properly draining the working fluid
from the drain port and is provided from the oil hole to the output
pressure oil passage.
[0016] Preferably, the oil hole is opened on a head of the nozzle
portion; the orifice port is opened to a side of the nozzle portion;
the side of the nozzle portion faces the supply pressure oil passage;
and the head of the nozzle portion faces the output pressure oil
passage.
[0017] Since an opening of the oil hole and an opening of the orifice
port are arranged separately at the head of the nozzle portion and
at the side of the nozzle portion, sealing between the supply pressure
oil passage and the output pressure oil passage can be easily achieved.
[0018] The above and further objects and features of the invention
will be more fully apparent from the following description when
the same is considered with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a sectional view showing an embodiment of the
present invention.
[0020] FIG. 2 is a view showing an example of a hydraulic circuit
to which the present invention is applied.
[0021] FIG. 3 is a view showing a conventional hydraulic circuit.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0022] Here will be described the embodiment of the invention with
reference to the accompanying drawings.
[0023] FIG. 1 is a sectional view of a solenoid valve circuit according
to an embodiment of the present invention.
[0024] In a valve body 10, a supply pressure oil passage 11 and
an output pressure oil passage 14 are arranged on a substantially
straight line, with a wall portion 13 disposed therebetween. This
makes it possible to form the oil passages by a single-layered construction
but not by a conventional double-layered construction having a separate
plate therebetween. The supply pressure oil passage 11 receives
working fluid from a not-shown pilot pressure valve.
[0025] End portions of the supply pressure oil passage 11 and the
output pressure oil passage 14, which are opposite to each other,
respectively have rising portions 12 and 15 extending along the
wall portion 13 to the direction of an upper surface of the valve
body 10.
[0026] The upper surface of the valve body 10 has a solenoid valve
attaching portion on which a two-way solenoid valve 30 is mounted,
with a nozzle portion 31 downward.
[0027] The nozzle portion 31 of the two-way solenoid valve 30 is
comprised of a large diameter portion 32 and a small diameter portion
33. An end of the small diameter portion 33 is fitted in a small
diameter portion receiving part 18 communicating with the rising
portion 15 of the output pressure oil passage 14, and the large
diameter portion 32 is fitted in a large diameter portion receiving
part 17 communicating with the rising portion 12 of the supply pressure
oil passage 11. Respective fitted portions are sealed in an oil-tight
manner by seal rings 36 and 37 which are held by ring grooves provided
in the nozzle portion 31.
[0028] In the center of the nozzle portion 31, there is provided
a through-hole 38 extending in the axial direction. An end of the
through-hole 38 faces the rising portion 15 of the output pressure
oil passage 14, and an inner end of the through-hole 38 opens to
a plunger chamber 40. The inner end of the through-hold 38 is provided
with a valve seat 39 protruding from the periphery. The plunger
chamber 40 is in communication with the external via a drain port
41.
[0029] The small diameter portion 33 of the nozzle portion 31 is
provided with an orifice port 43 in the vicinity of the large diameter
portion 32, and the orifice port 43 communicates with the through-hole
38 and is open to the side of the small diameter portion 33. Thereby,
the through-hole 38 communicates with the rising portion 12 of the
supply pressure oil passage 11 via the large diameter portion receiving
part 17 through the orifice port 43.
[0030] The end of a plunger 44 biased by a spring 45 abuts on the
valve sheet 39, and when electric current is supplied to a coil
46, the plunger 44 moves to open the through-hole 38. Electric current
supply from a not-shown oil pressure control unit to the coil 46
is subjected to duty control.
[0031] Thus, working fluid from the supply pressure oil passage
11 passes through the orifice port 43 of the two-way solenoid valve
30 and is fed to the through-hole 38 from which the working fluid
flows into the output pressure oil passage 14. During this feed,
the working fluid in the through-hole 38 is drained by a drain port
41 by opening and closing the inner end of the though-hole 38 by
the plunger 44, whereby the working fluid in the output pressure
oil passage 14 is regulated to a predetermined pressure by duty
control.
[0032] Since the solenoid valve circuit of the embodiment is constructed
as described above and the two-way solenoid valve 30 performing
drain control is provided with the orifice port 43, it is not necessary
to form an oil passage into a double-layered construction comprising
upper and lower layers between which a separate plate is disposed,
as in the prior art. By merely interposing the two-way solenoid
valve 30 in the middle of a single-layered oil passage, moreover,
the supply pressure oil passage 11 is defined on the upstream side
of the orifice port 43 and the output pressure oil passage 14 is
defined on the downstream side of the orifice port 43.
[0033] Therefore, the oil passage itself becomes simple and short,
the degree of freedom in the installation position of the two-way
solenoid valve is high, and also resistance to the flow of working
fluid becomes low.
[0034] Moreover, since the orifice port 43 is disposed in a two-way
solenoid valve which is attached to the outside of the valve body
10, the adjustment of the output pressure characteristics may be
accomplished by merely replacing with a two-way solenoid valve having
an orifice port of a different diameter. Thus, compared to the conventional
hydraulic circuit which requires disassembling the control valve
unit for exchange of a separate plate disposed between the upper
body and the lower body, the output pressure characteristics can
be quite easily adjusted.
[0035] Furthermore, the through-hole 38 is open at the head of
the nozzle portion, the orifice port 43 is open to the side of the
nozzle portion, the side of the nozzle portion faces the supply
pressure oil passage 11 and the head of the nozzle portion faces
the output pressure oil passage 14, as a result of which the positions
of respective openings are separated. By interposing a sealing member
37 therebetween, therefore, the supply pressure oil passage 11 can
be easily and reliably sealed with respect to the output pressure
oil passage 14.
[0036] According to this embodiment, the supply pressure oil passage
11 and the output pressure oil passage 14 are formed within the
valve body 10 by a boring operation, but these oil passages may
be formed by forming grooves on the undersurface of the valve body
10 and covering the undersurface with a plate.
[0037] Moreover, the orifice port 43 of the two-way solenoid valve
is open to the side of the small diameter portion 33 of the nozzle
portion and the through-hole 38 which is opened and closed by the
plunger 44 is open on the end face of the small diameter portion
33, but whether any of the through-hole and the orifice is opened
at the end face or to the side of the small diameter portion may
be optionally selected and a communicating passage with an corresponding
oil passage may be set depending on the position of openings. |