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Patent Abstract
In a proportional solenoid valve, a solenoid main body includes
a coil, a valve seat member having a seat portion, a valve element
that is displaced in accordance with a current applied to the coil
so as to be brought into and out of contact with the seat portion,
and a valve guide portion that is arranged coaxially with the seat
portion and guides the displacement of the valve element. The housing
is attached to the solenoid main body so that a space is formed
between the housing and the valve seat member. A seal member made
of an elastic material is provided in the space between the housing
and the valve seat member.
Patent Claims
What is claimed is:
1. A proportional solenoid valve comprising: a solenoid main body
including a coil, a valve seat member having a seat portion, a valve
element that is displaced in accordance with a current applied to
the coil so as to be brought into and out of contact with the seat
portion, and a valve guide portion that is arranged coaxially with
the seat portion and guides the displacement of the valve element;
a space is formed between the housing and the valve seat member,
and forms an input/output flow path of a fluid; and a seal member
that is made of an elastic material and is provided in the space.
2. A proportional solenoid valve according to claim 1, wherein
both of the valve guide portion and the valve seat member have a
cylindrical shape, and the valve seat member is fitted and fixed
around an outer peripheral surface of the valve guide portion.
3. A proportional solenoid valve according to claim 1, wherein
each of the valve guide portion and the valve seat member has a
cylindrical shape, and the valve seat member is welded and fixed
to a tip portion of the valve guide portion.
4. A proportional solenoid valve according to claim 1, wherein
the valve seat member has a cylindrical shape, and the valve guide
portion is formed integrally with the valve seat member.
Patent Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a proportional solenoid
valve in which a valve element is displaced by applying a current
to a solenoid to obtain an output pressure which is proportional
to the value of the applied current.
[0003] In a conventional proportional solenoid valve, a valve element
is displaced while being guided by a valve guide portion that is
provided for a solenoid main body. Also, a valve seat member having
a seat portion, which the valve element is brought into and out
of contact with, is fixed to a housing coupled to the solenoid main
body (see JP 2002-525524 A, for instance).
[0004] As described above, in the conventional proportional solenoid
valve, the valve element is provided on the solenoid main body side
and the seat portion is provided on the housing side, so that an
error occurs in the coupling position of the housing with reference
to the solenoid main body due to machining tolerances of the coupling
portion between the solenoid main body and the housing. As a result,
coaxiality between the valve element and the seat portion is lowered.
Also, when the housing is welded to the solenoid main body, a distortion
occurs in the housing, which causes a positional shift of the valve
element with reference to the seat portion. The influence of the
distortion varies depending on welding conditions such as the amount
of welding heat and a welding range, so that it is difficult to
manage the positional shift. Further, when the housing is made of
a resin, the positional shift of the valve element with reference
to the seat portion occurs also due to deformation of the housing
resulting from operating temperature.
SUMMARY OF THE INVENTION
[0005] The present invention has been made in order to solve the
above-mentioned problems, and provides a proportional solenoid valve
which is capable of improving accuracy of positional shift of a
valve element with reference to a seat portion.
[0006] A proportional solenoid valve according to the present invention
includes a solenoid main body, a housing, and a seal member. The
solenoid main body includes a coil, a valve seat member having a
seat portion, a valve element that is displaced in accordance with
a current applied to the coil so as to be brought into and out of
contact with the seat portion, and a valve guide portion that is
arranged coaxially with the seat portion and guides the displacement
of the valve element. The housing is attached to the solenoid main
body so that a space is formed between the housing and the valve
seat member. The seal member is made of an elastic material and
is provided in the space between the housing and the valve seat
member. The valve seat member is attached to the valve guide portion,
thereby making it possible to improve positional accuracy of the
valve element with reference to the seat portion.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] Preferred embodiments of the present invention will be described
in detail based on the following figures, wherein:
[0008] FIG. 1 is a cross-sectional view of a proportional solenoid
valve according to a first embodiment of the present invention;
[0009] FIG. 2 is a cross-sectional view of a proportional solenoid
valve according to a second embodiment of the present invention;
and
[0010] FIG. 3 is a cross-sectional view of a proportional solenoid
valve according to a third embodiment of the present invention;
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0011] Embodiments of the present invention will now be described
with reference to the accompanying drawings.
[0012] First Embodiment
[0013] FIG. 1 is a cross-sectional view of a proportional solenoid
valve according to a first embodiment of the present invention.
Note that in the drawing, a proportional solenoid valve of normally
high type is illustrated.
[0014] In FIG. 1, a coil 1 is accommodated in a cylindrical case
2 made of metal and a terminal 3 for connecting the coil 1 to a
power supply is arranged outside of the case 2. The coil 1 and the
terminal 3 are molded by a resin portion 4. A plunger accommodating
cavity 4a that extends in the axial direction of the coil 1 to pass
through the coil 1 is provided in the resin portion 4.
[0015] To one end portion of the resin portion 4, a core 5 made
of metal is coupled. This core 5 includes a cylinder portion 5a
inserted into one end portion of the plunger accommodating cavity
4a and a flange portion 5b that is abutted against an end surface
of the resin portion 4. The flange portion 5b is welded to the case
2 at the outer periphery of its joining surface with the case 2.
[0016] A first plain bearing 6 is inserted into the cylinder portion
5a. Also, a cylindrical adjuster 7 is press-fitted into the cylinder
portion 5a.
[0017] To the other end portion of the resin portion 4, a guide
member 8 made of metal is coupled. This guide member 8 includes
an annular-shaped flange portion 8a abutted against an end surface
of the resin portion 4, a cylindrical fit portion 8b that protrudes
from the flange portion 8a, and a cylindrical valve guide portion
8c that extends from one end portion of the fit portion 8b. The
flange portion 8a is welded to the case 2 at the outer periphery
of its joining surface with the case 2. The diameter of the valve
guide portion 8c is smaller than the diameter of the fit portion
8b.
[0018] A second plain bearing 9 is fixed into the valve guide portion
8c. Into the first plain bearing 6 and the second plain bearing
9, a rod 10 is inserted so as to be slidable. This rod 10 is arranged
inside of the core 5, the plunger accommodating cavity 4a, and the
guide member 8 so as to be capable of reciprocating in the axial
direction of the coil 1.
[0019] To the middle portion of the rod 10, a cylindrical plunger
11 is fixed. That is, the rod 10 is press-fitted into the plunger
11. A first spring 12 is arranged between the plunger 11 and the
first plain bearing 6, while a second spring 13 is arranged between
the plunger 11 and the second plain bearing 9. The plunger 11 is
capable of reciprocating integrally with the rod 10 inside of the
plunger accommodating cavity 4a.
[0020] A ball-shaped valve element 14 is inserted into the valve
guide portion 8c. A tip portion of the rod 10 is abutted against
the valve element 14. The load of the first spring 12 energizing
the plunger 11 toward the valve element 14 is adjusted by the press-fit
position of the adjuster 7. The valve guide portion 8c is press-fitted
into and is fixed to a valve seat member 15. The valve seat member
15 includes a cylindrical fixing portion 15a into which the valve
guide portion 8c is press-fitted, a seat portion 15b which the valve
element 14 is brought into and out of contact with, an input/output-side
oil passage 15c, and a drain-side oil passage 15d.
[0021] To the guide member 8, a housing 16 that forms a flow path
for oil (oil passage) is attached. This housing 16 is welded to
the flange portion 8a at the outer periphery of its joining surface
with the flange portion 8a. Also, the housing 16 includes an input
portion 16a, an output portion 16b, and a drain port 16c.
[0022] The output port 16b communicates with the input/output-side
oil passage 15c, and the drain port 16c communicates with the drain-side
oil passage 15d. Also, the housing 16 is provided with a valve seat
insertion portion 16d into which an end portion of the valve seat
member 15 is inserted. Between the inner peripheral surface of the
valve seat insertion portion 16d and the valve seat member 15, a
space having a predetermined size is provided, and a seal member
17, such as an O-ring made of an elastic material, is provided in
the space.
[0023] Here, the space between the valve seat member 15 and the
housing 16, in which the seal member 17 is placed, is set with consideration
given to machining accuracy of the valve seat member 15 and the
housing 16, the space between the guide member 8 and the housing
16 in the radius direction of their coupling portion, thermal expansion
of the valve seat member 15 and the housing 16 due to an operating
temperature, and the like. When the diametral space between the
guide member 8 and the housing 16 is set at around 0.1 mm, for instance,
the space between the valve seat member 15 and the housing 16 is
set larger than the diametral space by around 0.1 mm, that is, at
around 0.2 mm.
[0024] Also, the case 2, the core 5, the guide member 8, and the
plunger 11 collectively constitute a magnetic circuit. The core
5 functions as a magnetic attraction portion for the plunger 11.
A solenoid main body 20 in the first embodiment includes the coil
1, the case 2, the terminal 3, the resin portion 4, the core 5,
the first plain bearing 6, the adjuster 7, the guide member 8, the
second plain bearing 9, the rod 10, the plunger 11, the first spring
12, the second spring 13, the valve element 14, and the valve seat
member 15. To the housing 16, a flange member 18 for attachment
is fixed.
[0025] Next, an operation in this embodiment will be described.
Under a state where the coil 1 is not excited, the plunger 11 is
pressed to the valve element 14 side by the spring force of the
first spring 12. Consequently, the valve element 14 is pressed against
the seat portion 15b by the rod 10, and the oil flow path to the
drain port 16c is closed. As a result, a high-pressure output is
obtained from the output port 16b.
[0026] When the coil 1 is excited and an electromagnetic force
attracting the plunger 11 exceeds a predetermined degree, the plunger
11 and the rod 10 are displaced in opposition to the spring force
of the first spring 12 in a direction in which distances of the
plunger 11 and the rod 10 from the seat portion 15b are increased.
At that time, oil pressure acts on the valve element 14, so that
the valve element 14 is displaced within the valve guide portion
8c along with the rod 10. As a result, the valve element 14 is spaced
from the seat portion 15b, an amount of oil corresponding to the
opening degree is output to the drain port 16c side, and the pressure
output from the output port 16b is reduced. The valve element 14
is displaced in accordance with the value of a current applied to
the coil 1 and an output proportional to the current value is obtained
from the output port 16b.
[0027] In this proportional solenoid valve, the valve seat member
15 is attached to the valve guide portion 8c, so that it becomes
possible to improve the positional accuracy of the valve element
14 with reference to the seat portion 15b by eliminating the influence
of a positional shift between the guide member 8 and the housing
16 and a distortion of the housing 16. As a result, coaxiality between
the valve guide portion 8c and the valve seat member 15 and perpendicularity
between the valve guide portion 8c and the seat portion 15b are
improved, which makes it possible to improve seatability and stability
of output characteristics. Further, it becomes possible to increase
machining tolerances of the coupling portion between the solenoid
main body 20 and the housing 16.
[0028] Also, the housing 16 is a component whose function is only
to form an oil path, which makes it possible to deal with this housing
16 as a component that exerts no influence on the seatability and
the output characteristics. As a result, it becomes possible to
increase flexibility concerning the shape and material of the housing
16, which contributes to cost reduction. Also, even when the housing
16 is made of a resin and is deformed due to operating temperatures,
it becomes possible to prevent the positional shift of the valve
member 14 with reference to the seat portion 15b. Further, even
when the proportional solenoid valve according to the present invention
is attached to transmissions (electronically controlled automatic
transmissions for automobiles) having different attachment specifications,
for instance, it becomes possible to cope with such various transmissions
merely by changing the shape and material of the housing 16 while
achieving commonality of components on the solenoid main body 20
side, which facilitates simplification of evaluations of proportional
solenoid valves.
[0029] Second Embodiment
[0030] Next, a second embodiment of the present invention will
be described. FIG. 2 is a cross-sectional view of a proportional
solenoid valve according to the second embodiment. In the drawing,
the valve guide portion 8c is provided with a drain-side oil flow
path 8d that guides a part of the oil from the input port 16a to
the drain port 16c side when the valve element 14 is set in an opened
state. To a tip portion of the valve guide portion 8c, a valve seat
member 21 after abutment is welded and fixed. This valve seat member
21 includes a seat portion 21a, with which the valve element 14
is brought into and out of contact, and an input/output-side oil
flow path 21b. Between the inner peripheral surface of the valve
seat insertion portion 16d and the valve seat member 21, a space
having a predetermined size is provided, and the seal member 17,
such as an O-ring made of an elastic material, is provided therein.
Other constructions are the same as those in the first embodiment.
[0031] Even when the valve seat member 21 is welded to the valve
guide portion 8c in that manner, it is possible to provide the same
effects as in the first embodiment. Also, it is possible to weld
the valve seat member 21 to the valve guide portion 8c merely by
performing spot welding at several points at the outer periphery
of the joining surface therebetween, which makes it possible to
neglect the influence of welding distortion.
[0032] Third Embodiment
[0033] Next, a third embodiment of the present invention will be
described. FIG. 3 is a cross-sectional view of a proportional solenoid
valve according to the third embodiment of the present invention.
In the drawing, a guide member 22 made of metal is coupled to the
resin portion 4. This guide member 22 includes an annular-shaped
flange portion 22a abutted against an end surface of the resin portion
4, and a cylindrical fit portion 22b that protrudes from the flange
portion 22a. The flange portion 22a is welded to the case 2 at the
outer periphery of its joining surface with the case 2.
[0034] Into the fit portion 22b, a cylindrical valve seat member
23 is fitted and fixed. This valve seat member 23 includes a valve
guide portion 23a that guides the displacement of the valve member
14, a seat portion 23b which the valve element 14 is brought into
and out of contact with, an input/output-side oil flow path 23c,
and a drain-side oil flow path 23d.
[0035] The second plain bearing 9 is inserted into the valve guide
portion 23a and fixed. Between the inner peripheral surface of the
valve seat insertion portion 16d and the valve seat member 23, a
space having a predetermined size is provided and the seal member
17, such as an O-ring made of an elastic material, is provided in
the space. Other constructions are the same as those in the first
embodiment.
[0036] Even when the valve guide portion 23a is formed integrally
with the valve seat member 23 in that manner, it is possible to
produce the same effects as in the first embodiment. Also, the valve
guide portion 23a is formed integrally with the valve seat member
23, so that it becomes possible to further improve the positional
accuracy between the valve element 14 and the seat portion 23b.
[0037] Note that, in the first to third embodiments, there was
described a proportional solenoid valve of a normally high type
whose output pressure is high at the time of non-energization and
is decreased in accordance with an increase in applied current.
However, the present invention is also applicable to a proportional
solenoid valve of a normally low type whose output pressure is low
at the time of non-energization and is increased in accordance with
an increase in applied current. Also, the housing can be shared
between two types of proportional solenoid valves.
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