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Patent Abstract
A solenoid valve includes an electromagnetic drive unit for generating
a magnetomotive force when being fed with electric power. There
are a controlled-fluid passage and an accommodation chamber containing
the electromagnetic drive unit. A partition wall defines a part
of the controlled-fluid passage. A valve opening extends through
the partition wall. A shaft extending through the valve opening
is driven by the electromagnetic drive unit. A valve member fixed
to the shaft moves into and out of contact with the partition wall
to block and unblock the valve opening in accordance with movement
of the shaft. A thin-film sealing member made of rubber-based resilient
material operates for airtightly separating the controlled-fluid
passage and the accommodation chamber from each other. A communication
passage connects the accommodation chamber and an exterior. An orifice
provides a smaller effective cross-sectional area of the communication
passage.
Patent Claims
What is claimed is:
1. A solenoid valve comprising: (a) an electromagnetic drive unit
for generating a magnetomotive force when being fed with electric
power; (b) a member having a controlled-fluid passage and an accommodation
chamber containing the electromagnetic drive unit; (c) a partition
wall defining a part of the controlled-fluid passage; (d) a valve
opening extending through the partition wall; (e) a shaft extending
through the valve opening and being driven by the electromagnetic
drive unit; (f) a valve member fixed to the shaft and moving into
and out of contact with the partition wall to block and unblock
the valve opening in accordance with movement of the shaft; (g)
a thin-film sealing member made of rubber-based resilient material
for airtightly separating the controlled-fluid passage and the accommodation
chamber from each other; (h) a communication passage connecting
the accommodation chamber and an exterior; and (i) an orifice providing
a smaller effective cross-sectional area of the communication passage.
2. A solenoid valve comprising: (a) an electromagnetic drive unit
for generating a magnetomotive force when being fed with electric
power; (b) a member having a controlled-fluid passage and an accommodation
chamber containing the electromagnetic drive unit; (c) a partition
wall defining a part of the controlled-fluid passage; (d) a valve
opening extending through the partition wall; (e) a shaft extending
through the valve opening and being driven by the electromagnetic
drive unit; (f) a valve member fixed to the shaft and moving into
and out of contact with the partition wall to block and unblock
the valve opening in accordance with movement of the shaft; and
(g) a thin-film sealing member made of rubber-based resilient material
for airtightly separating the controlled-fluid passage and the accommodation
chamber from each other, the thin-film sealing member having a first
portion and a second portion, the second portion extending around
the first portion, the first portion being less resiliently deformable
than the second portion.
3. A solenoid valve as recited in claim 2, wherein the first portion
is harder than the second portion.
4. A solenoid valve as recited in claim 2, wherein the first portion
is thicker than the second portion.
5. A solenoid valve as recited in claim 4, wherein the first portion
extends over a central area of the thin-film sealing member, and
the first portion includes an engagement portion in contact with
the shaft and a peripheral portion near the engagement portion.
6. A solenoid valve as recited in claim 1, wherein the partition
wall forms a valve seat with which the valve member is moved into
and out of contact.
7. A solenoid valve as recited in claim 1, wherein the partition
wall has a projection forming a shaft support for locating the shaft
radially while allowing axial movement of the shaft.
8. A solenoid valve as recited in claim 7, wherein the projection
of the partition wall forms a stopper engageable with a projection
on the shaft.
9. A solenoid valve as recited in claim 7, wherein the projection
on the shaft has a cross section of a shape corresponding to an
inner shape of the shaft support.
10. A solenoid valve comprising: a housing defining a fluid passage;
a valve seat defining a part of the fluid passage; a valve member
movable into and out of contact with the valve seat to block and
unblock the fluid passage; a shaft; a fixing member for fixing the
valve member to the shaft; a movable iron core holding the shaft
and forming a first part of a magnetic circuit; a fixed iron core
facing the movable iron core and forming a second part of the magnetic
circuit; and a coil extending around the movable iron core and the
fixed iron core and generating a magnetic force to move the movable
iron core toward the fixed iron core when being fed with electric
power; wherein a portion of the fixing member is spaced from a corresponding
portion of the valve member by a gap for allowing deformation of
the valve member.
11. A solenoid valve as recited in claim 10, wherein the fixing
member has a first portion and a second portion, the first portion
extending around the second portion and being thinner than the second
portion.
12. A solenoid valve as recited in claim 10, wherein the gap is
provided by a step on at least one of the fixing member and the
valve member.
Patent Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention generally relates to a solenoid valve or
an electrically-powered valve for controlling a flow of fluid such
as air. This invention particularly relates to a solenoid valve
which can be used in an evaporative control system to selectively
block and unblock a charcoal-canister pipe opening into the atmosphere.
[0003] 2. Description of the Related Art
[0004] Japanese patent application publication number 7-233882
(application number 6-24075) discloses a solenoid valve for selectively
blocking and unblocking communication between a first passage and
a second passage. The solenoid valve in Japanese application 7-233882
includes a fixed iron core, a first movable member, and a second
movable member. The fixed iron core is magnetized when a coil is
energized. The second movable member is formed of a permanent magnet.
The magnetic poles of the permanent magnet are arranged so that
the permanent magnet repels the fixed iron core when the coil is
energized. As the second movable member moves, the first movable
member comes into contact with a valve seat defining a portion of
the second passage. When the first movable member is in contact
with the valve seat, communication between the first passage and
the second passage is blocked. An operation chamber extends between
the first movable member and the second movable member. The first
movable member includes a valve member and an annular diaphragm.
The annular diaphragm extends radially outward from the valve member.
Thus, the inner circumferential edge of the diaphragm is connected
with the valve member. The outer circumferential edge of the diaphragm
is connected with a coil hold member. The valve member is movably
supported by the diaphragm. The valve member has a first through
hole for providing communication between the operation chamber and
the second passage. The diaphragm has a second through hole for
providing communication between the operation chamber and the first
passage. When the valve member is separated from the valve seat,
the operation chamber and the second passage communicate with each
other via the first through hole. When the valve member is in contact
with the valve seat, the first through hole is closed by the second
movable member so that the operation chamber and the second passage
are disconnected from each other. On the other hand, the operation
chamber and the first passage remain in communication with each
other via the second through hole regardless of whether the valve
member separates from or contacts with the valve seat.
[0005] Japanese patent application publication number 8-312827
(application number 7-115918) discloses a solenoid valve including
a coil, a moving core, and a yoke. The coil is supported by a coil
hold member. The moving core is moved as the coil is energized and
de-energized. The yoke has a valve portion formed with a communication
hole and a valve seat around the communication hole. A valve rubber
is mounted on the moving core. When the coil is de-energized, the
moving core is positioned by a return spring so that the valve rubber
is separate from the valve seat. Thus, in this case, the communication
hole is unblocked. When the coil is energized, the moving core is
moved toward the valve portion of the yoke and the valve rubber
comes into contact with the valve seat. Thus, in this case, the
communication hole is blocked. The moving core has a cylindrical
portion extending into a central bore of the coil hold member.
[0006] Japanese patent application publication number 8-270818
(application number 7-69817) discloses a solenoid valve similar
in structure to the solenoid valve of Japanese application 8-312827.
SUMMARY OF THE INVENTION
[0007] It is an object of this invention to provide a solenoid
valve which generates only low-level noise or reduced-level noise
when a valve member meets a valve seat.
[0008] A first aspect of this invention provides a solenoid valve
comprising (a) an electromagnetic drive unit for generating a magnetomotive
force when being fed with electric power; (b) a member having a
controlled-fluid passage and an accommodation chamber containing
the electromagnetic drive unit; (c) a partition wall defining a
part of the controlled-fluid passage; (d) a valve opening extending
through the partition wall; (e) a shaft extending through the valve
opening and being driven by the electromagnetic drive unit; (f)
a valve member fixed to the shaft and moving into and out of contact
with the partition wall to block and unblock the valve opening in
accordance with movement of the shaft; (g) a thin-film sealing member
made of rubber-based resilient material for airtightly separating
the controlled-fluid passage and the accommodation chamber from
each other; (h) a communication passage connecting the accommodation
chamber and an exterior; and (i) an orifice providing a smaller
effective cross-sectional area of the communication passage.
[0009] A second aspect of this invention provides a solenoid valve
comprising (a) an electromagnetic drive unit for generating a magnetomotive
force when being fed with electric power; (b) a member having a
controlled-fluid passage and an accommodation chamber containing
the electromagnetic drive unit; (c) a partition wall defining a
part of the controlled-fluid passage; (d) a valve opening extending
through the partition wall; (e) a shaft extending through the valve
opening and being driven by the electromagnetic drive unit; (f)
a valve member fixed to the shaft and moving into and out of contact
with the partition wall to block and unblock the valve opening in
accordance with movement of the shaft; and (g) a thin-film sealing
member made of rubber-based resilient material for airtightly separating
the controlled-fluid passage and the accommodation chamber from
each other, the thin-film sealing member having a first portion
and a second portion, the second portion extending around the first
portion, the first portion being less resiliently deformable than
the second portion.
[0010] A third aspect of this invention is based on the second
aspect thereof, and provides a solenoid valve wherein the first
portion is harder than the second portion.
[0011] A fourth aspect of this invention is based on the second
aspect thereof, and provides a solenoid valve wherein the first
portion is thicker than the second portion.
[0012] A fifth aspect of this invention is based on the fourth
aspect thereof, and provides a solenoid valve wherein the first
portion extends over a central area of the thin-film sealing member,
and the first portion includes an engagement portion in contact
with the shaft and a peripheral portion near the engagement portion.
[0013] A sixth aspect of this invention is based on the first aspect
thereof, and provides a solenoid valve wherein the partition wall
forms a valve seat with which the valve member is moved into and
out of contact.
[0014] A seventh aspect of this invention is based on the first
aspect thereof, and provides a solenoid valve wherein the partition
wall has a projection forming a shaft support for locating the shaft
radially while allowing axial movement of the shaft.
[0015] An eighth aspect of this invention is based on the seventh
aspect thereof, and provides a solenoid valve wherein the projection
of the partition wall forms a stopper engageable with a projection
on the shaft.
[0016] A ninth aspect of this invention is based on the seventh
aspect thereof, and provides a solenoid valve wherein the projection
on the shaft has a cross section of a shape corresponding to an
inner shape of the shaft support.
[0017] A tenth aspect of this invention provides a solenoid valve
comprising a housing defining a fluid passage; a valve seat defining
a part of the fluid passage; a valve member movable into and out
of contact with the valve seat to block and unblock the fluid passage;
a shaft; a fixing member for fixing the valve member to the shaft;
a movable iron core holding the shaft and forming a first part of
a magnetic circuit; a fixed iron core facing the movable iron core
and forming a second part of the magnetic circuit; and a coil extending
around the movable iron core and the fixed iron core and generating
a magnetic force to move the movable iron core toward the fixed
iron core when being fed with electric power; wherein a portion
of the fixing member is spaced from a corresponding portion of the
valve member by a gap for allowing deformation of the valve member.
[0018] An eleventh aspect of this invention is based on the tenth
aspect thereof, and provides a solenoid valve wherein the fixing
member has a first portion and a second portion, the first portion
extending around the second portion and being thinner than the second
portion.
[0019] A twelfth aspect of this invention is based on the tenth
aspect thereof, and provides a solenoid valve wherein the gap is
provided by a step on at least one of the fixing member and the
valve member.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 is a sectional view of a prior-art solenoid valve.
[0021] FIG. 2 is a diagram of an evaporative control system for
a vehicle which includes a solenoid valve according to a first embodiment
of this invention.
[0022] FIG. 3 is a sectional view of the solenoid valve in FIG.
2.
[0023] FIG. 4 is a sectional view of a shaft, shaft supports, and
a valve opening in FIG. 3.
[0024] FIG. 5 is a sectional view of the solenoid valve which is
in its open state.
[0025] FIG. 6 is a sectional view of a portion of the solenoid
valve which is in its open state.
[0026] FIG. 7 is a sectional view of the solenoid valve which is
in its closed state.
[0027] FIG. 8 is a sectional view of a portion of the solenoid
valve which is in its closed state.
[0028] FIG. 9 is a plan view of a tubular member and the valve
opening in FIG. 3.
[0029] FIG. 10 is a plan view of the valve opening, the shaft supports,
the shaft, an end projection on the shaft, and a valve seat in FIG.
3.
[0030] FIG. 11 is a sectional view of the valve opening, the shaft
supports, the shaft, a central projection on the shaft, and the
valve seat in FIG. 3.
[0031] FIG. 12 is a sectional view of a solenoid valve in its open
state according to a ninth embodiment of this invention.
[0032] FIG. 13 is a sectional view of the solenoid valve in its
closed state according to the ninth embodiment of this invention.
[0033] FIG. 14 is a sectional view of a portion of a solenoid valve
according to a tenth embodiment of this invention.
[0034] FIG. 15 is a sectional view of a portion of a solenoid valve
according to an eleventh embodiment of this invention.
DETAILED DESCRIPTION OF THE INVENTION
[0035] A prior-art solenoid valve will be explained below for a
better understanding of this invention.
[0036] With reference to FIG. 1, a prior-art solenoid valve 901
includes a coil 903, a fixed iron core 908, and a movable iron core
909. A valve member 912 is mounted on a shaft 911 fixed to the movable
iron core 909. Walls defining a portion of a passage 914b have a
valve seat 914a. When the coil 903 is energized, the movable iron
core 909 and the shaft 911 are moved toward the fixed iron core
908 so that the valve member 912 comes into contact with the valve
seat 914a. In this case, the passage 914b is blocked. When the coil
903 is de-energized, a return spring 910 moves the movable iron
core 909 and the shaft 911 away from the fixed iron core 908 so
that the valve member 912 separates from the valve seat 914a. In
this case, the passage 914b is unblocked. The movable iron core
909 continues to be moved away from the fixed iron core 908 until
meeting a stopper 915.
[0037] In the prior-art solenoid valve 901, the movable iron core
909 has a cylindrical main body. The shaft 911 axially extends from
the cylindrical main body of the movable iron core 909. A distal
end of the shaft 911 has a flange 911a and an axial projection 911b.
The valve member 912 fits around the projection 911b. The valve
member 912 contacts the flange 911a. A disk 923 fits around the
projection 911b. The disk 923 contacts the valve member 912. The
disk 923 is approximately equal in outside diameter to the valve
member 912. A snap washer 922 mounted on the projection 911b presses
the disk 923 against the valve member 912, thereby thrusting the
valve member 912 against the flange 911a. Thus, the valve member
912 is fixed to the shaft 911. The valve member 912 moves together
with the shaft 911, that is, moves together with the movable iron
core 909.
[0038] In the prior-art solenoid valve 901, the disk 923 is made
of hard resin. In some cases, noise is generated at a considerable
level when the valve member 912 meets the valve seat 914a.
First Embodiment
[0039] With reference FIG. 2, an evaporative control system for
a vehicle is associated with a fuel tank 101. The evaporative control
system includes a canister 102 filled with adsorbent such as activated
charcoal. A pipe 104 connects the fuel tank 101 and the canister
102. A pipe 105 connects the canister 102 with a portion of an engine
air passage 103 downstream of a throttle valve.
[0040] Fuel vapor is guided from the fuel tank 101 to the canister
102 via the pipe 104 before being adsorbed by the canister 102.
Fuel vapor released from the canister 102 is drawn into the engine
air passage 103 via the pipe 105. Thus, purging is implemented with
respect to fuel vapor. The evaporative control system prevents fuel
vapor from being emitted into the atmosphere.
[0041] A pressure sensor 106 is connected with the pipe 104. A
purge valve 107 is interposed in the pipe 105. A pipe 109 extending
from the canister 102 opens into the atmosphere.
[0042] The evaporative control system includes a solenoid valve
1 according to a first embodiment of this invention. The solenoid
valve 1 is interposed in the pipe 109. The solenoid valve 1 selectively
blocks and unblocks the pipe 109. When the pipe 109 is unblocked,
an atmosphere (air) is permitted to enter the canister 102. When
the pipe 109 is blocked, an atmosphere (air) is inhibited from entering
the canister 102. In addition, the escape of fuel vapor from the
canister 102 into the atmosphere is avoided.
[0043] While a vehicular engine is operating and hence a vacuum
is developed in a region of the engine air passage 103 downstream
of the throttle valve, the evaporative control system implements
a check on the leak of fuel vapor as follows. The pipe 109 is blocked
by the solenoid valve 1. Then, the purge valve 107 is opened so
that the pipes 104 and 105 and the canister 102 are subjected to
a vacuum. Subsequently, the purge valve 107 is closed. At a predetermined
time after the moment when the purge valve 107 is closed, a measurement
is given of whether or not a pressure rise is detected by the pressure
sensor 106. A decision is made as to the leak of fuel vapor on the
basis of the result of the measurement.
[0044] The solenoid valve 1 will be described below in more detail.
With reference to FIGS. 3-11, the solenoid valve 1 is of a normally
open type. The solenoid valve 1 includes a housing 2 in which a
tubular or cylindrical member 3 is fixedly disposed. An electromagnetic
drive unit including a coil 4 is located in the tubular member 3.
As will be made clear later, a shaft 7 is axially moved by the electromagnetic
drive unit. A disk-shaped valve member 8 is coaxially mounted on
the shaft 7. The valve member 8 moves together with the shaft 7.
A diaphragm 9 is provided between the tubular member 3 and the shaft
7. A passage 10 for controlled fluid (controlled air) extends in
the housing 2. The diaphragm 9 airtightly or fluidtightly separates
a first control chamber 11 and a second control chamber 12 from
each other. The second control chamber 12 extends in the tubular
member 3.
[0045] The housing 2 is made of electrically-insulating resin.
The housing 2 has a cylindrical pipe 23 and a partially cylindrical
pipe 24. The interiors of the pipes 23 and 24 form a passage 22
for controlled fluid (controlled air). The controlled-fluid passage
22 constitutes a portion of the controlled-fluid passage 10. In
FIG. 3, the controlled-fluid passage 22 opens into the atmosphere
at its upper end. The housing 2 is integrally formed with a connector
portion 26. A pair of terminals 25 are inserted into the connector
portion 26. The terminals 25 provide electrical connection between
the coil 4 and an external power supply. In FIG. 3, a flange 3A
on the tubular member 3 fits in a lower end of the housing 2. For
example, a heating process is carried out to provide airtight or
fluidtight engagement between the flange 3A on the tubular member
3 and the lower end of the housing 2.
[0046] The tubular member 3 is made of electrically-insulating
resin. The first and second control chambers 11 and 12 extend in
an interior of a portion of the tubular member 3 above its flange
3A as viewed in FIG. 3. The first control chamber 11 is located
immediately above the flange 3A. The first control chamber 11 communicates
with the controlled-fluid passage 22. The electromagnetic drive
unit (the coil 4) is located in the second control chamber 12. In
FIG. 3, a portion of the tubular member 3 below its flange 3A has
a central hole constituting a passage 21 for controlled fluid (controlled
air). The passage 21 is referred to as the first controlled-fluid
passage. On the other hand, the passage 22 is referred to as the
second controlled-fluid passage. Basically, the first controlled-fluid
passage 21, the second controlled-fluid passage 22, and the first
control chamber 11 compose the controlled-fluid passage 10. The
tubular member 3 is integrally formed with partition walls 13 projecting
radially inward which separate the first control chamber 11 and
the second controlled-fluid passage 21 from each other. The inner
edges of the partition walls 13 define a valve opening 14 of a predetermined
shape (see FIG. 9). The valve opening 14 has sectoral portions.
The valve opening 14 forms a part of the controlled-fluid passage
10. When the solenoid valve 1 is in its open state, the first control
chamber 11 and the first controlled-fluid passage 21 communicate
with each other via the valve opening 14. When the solenoid valve
1 is in its closed state, the valve opening 14 is closed so that
communication between the first control chamber 11 and the first
controlled-fluid passage 21 is blocked. The partition walls 13 have
radially-inward projections constituting shaft supports 15. As best
shown in FIG. 9, the shaft supports 15 are spaced at equal angular
intervals. The number of the shaft supports 15 is equal to, for
example, three. The sectoral portions of the valve opening 14 are
located between the shaft supports 15.
[0047] As shown in FIGS. 9, 10, and 11, the valve opening 14 has
sectoral portions defined by the inner circumferential surfaces
of the partition walls 13 and the side surfaces of the shaft supports
15. The valve opening 14 has an inside diameter of, for example,
4.2 mm. The shaft supports 15 extend radially inward from the inner
circumferential surfaces of the partition walls 13. The shaft supports
15 have a thickness of, for example, 1.5 mm. The shaft supports
15 have a width of, for example, 1.5 mm. The shaft supports 15 form
stoppers 47 for the shaft 7. A projection 62 on the shaft 7 can
meet the stoppers 47 (the shaft supports 15).
[0048] In FIG. 3, the inner edges of the partition walls 13 have
an axial downward projection forming a valve seat 16 of a circular
ring shape. The height (the axial dimension) of the valve seat 16
from the lower base surface of the partition walls 13 is equal to,
for example, 2 mm. The walls of the valve seat 16 have a thickness
of, for example, 1.5 mm. The distal end of the valve seat 16 is
tapered. The valve seat 16 may be covered with a cushion rubber
or a rubber-based resilient member. The valve seat 16 extends around
the valve opening 14. The tubular member 3 has a radially-extending
hole 17 of an approximately circular cross-section which forms a
part of the first control chamber 11, and which is located above
the partition walls 13. The tubular member 3 has engagement walls
19 which project radially inward, and which are of a circular ring
shape. The engagement walls 19 support the outer circumferential
edge of the diaphragm 9. A portion of the engagement walls 19 extends
immediately above the hole 17.
[0049] In FIG. 3, a lower end of the tubular member 3 forms a pipe
30 of a circular cross-section. The first controlled-fluid passage
21 extends in the pipe 30. The pipe 30 is connected with the pipe
109 (see FIG. 2) leading from the canister 102 (see FIG. 2). A sealing
member 33 such as an O-ring fits into an annular groove 34 in the
outer circumferential surfaces of the pipe 30. The sealing member
33 provides airtight or fluidtight connection between the pipes
30 and 109. The upper end of the tubular member 3 abuts against
the walls 27 of a closed upper end of the housing 2. A sealing member
35 such as a packing fits in a ring groove 36 in the upper end surface
of the tubular member 3. The sealing member 35 provides airtight
or fluidtight contact between the upper end of the tubular member
3 and the closed upper end of the housing 2.
[0050] The second control chamber 12 extends in the tubular member
3. The electromagnetic drive unit (the coil 4) is disposed in the
second control chamber 12. The electromagnetic drive unit includes
a cylindrical bobbin 5, a stator core (a fixed iron core) 6, a yoke
51, a plate magnetic 52, a moving core 53, and a return spring 54.
The coil 4 is wound on the bobbin 5. The stator core 6 extends inward
of the bobbin 5. The stator core 6 is made of magnetic material.
The yoke 51 is made of magnetic material. The plate magnetic 52
is made of magnetic material. The moving core 53 is made of magnetic
material. The stator core 6, the yoke 51, the plate magnetic 52,
and the moving core 53 compose a magnetic circuit. The moving core
53 is mounted on the shaft 7. The moving core 53 moves together
with the shaft 7. The return spring 54 urges the moving core 53
relative to the stator core 6 toward a position corresponding to
the open state of the solenoid valve 1. The return spring 54 is
of a helical shape.
[0051] The coil 4 has turns provided on the outer circumferential
surfaces of the bobbin 5. Ends of the coil 4 are electrically connected
to the power supply via the terminals 25. The bobbin 5 is made of
electrically-insulating material. The stator core 6 has a projection
which is fitted into a hole in the yoke 51 by a pressing process.
Thus, the stator core 6 and the yoke 51 are fixed to each other.
The yoke 51 is of an approximately L-shaped section. In FIG. 3,
the yoke 51 is held between the upper end walls of the housing 2
and the engagement walls 19 of the tubular member 3. The yoke 51
is fixed in the tubular member 3.
[0052] The plate magnetic 52 has a cylindrical portion extending
axially with respect to the tubular member 3, and an annular portion
(a flange portion) extending radially outward from a lower end of
the cylindrical portion. In FIG. 3, the annular portion (the flange
portion) of the plate magnetic 52 is supported between the lower
end of the yoke 51 and the engagement walls 19 of the tubular member
3. The moving core 53 slidably extends into a bore of the cylindrical
portion of the plate magnetic 52. The moving core 53 is movably
supported by the plate magnetic 52. The moving core 53 is located
by the plate magnetic 52 in the radial direction. In FIG. 3, a lower
end of the stator core 6 has a recess. An upper end of the moving
core 53 has a projection facing the recess in the stator core 6.
When the coil 4 is energized, there occurs a magnetomotive force
driving the moving core 53 toward the stator core 6. At this time,
the projection of the moving core 53 moves into the recess in the
stator core 6. The return spring 54 urges an axially-movable set
of the shaft 7, the valve member 8, the diaphragm 9, and the moving
core 53 toward a position corresponding to the closed state of the
solenoid valve 1. The return spring 54 is provided between the stator
core 6 and the moving core 53. An upper portion of the return spring
54 is supported in the recess of the stator core 6. A lower portion
of the return spring 54 is supported in a recess of the moving core
53.
[0053] The shaft 7 is made of resin. The shaft 7 extends through
the valve opening 14. In addition, the shaft 7 extends along the
axis of the tubular member 3. The shaft 7 is axially movable. The
shaft 7 moves together with the moving core 53. A portion of the
shaft 7 in and near the valve opening 14 has an outside diameter
of, for example, 4 mm. As best shown in FIG. 4, this portion of
the shaft 7 is slidably supported by the end surfaces of the shaft
supports 15. Thus, the shaft 7 is located by the shaft supports
15 in the radial direction.
[0054] As best shown in FIGS. 3 and 10, the shaft 7 has a radially-outward
projection 61 of a shape corresponding to the shapes of the valve
opening 14 and the shaft supports 15. The projection 61 on the shaft
7 has sectoral segments similar in shape to the sectoral portions
of the valve opening 14. The projection 61 has an outside diameter
of, for example, 7 mm. In FIG. 3, the projection 61 extends below
the shaft supports 15. The projection 61 is referred to as the end
projection. As best shown in FIGS. 3 and 11, the shaft 7 has a radially-outward
projection 62. The projection 62 has an outside diameter of, for
example, 7 mm. In FIG. 3, the projection 62 extends above the shaft
supports 15. The projection 62 is referred to as the central projection.
The central projection 62 can meet the stoppers 47 formed by the
upper surfaces of the shaft supports 15. The end projection 61 and
the central projection 62 are equal in shape. Thus, the central
projection 62 has sectoral segments. An upper portion of the shaft
7 is inserted into an axial hole of the moving core 53. The shaft
7 is fixed to the moving core 53 by a thermally deforming process.
[0055] The valve member 8 is made of rubber-based resilient material,
for example, HNBR resistant to gasoline. Here, HNBR means nitrile-butadiene
rubber (NBR) to which hydrogen is added through double bond. HNBR
is better than NBR in heat-resisting performances. The valve member
8 is basically of a disk shape coaxial with the shaft 7. The valve
member 8 extends in the first controlled-fluid passage 21 within
the tubular member 3. In FIG. 3, the valve member 8 is located below
the end projection 61 of the shaft 7. The valve member 8 axially
moves together with the shaft 7. When the solenoid valve 1 is in
its closed state, the valve member 8 contacts the valve seat 16
and hence blocks the valve opening 14. A ring-shaped washer 63 in
engagement with the shaft 7 presses the valve member 8 against the
end projection 61 of the shaft 7, thereby fixing the valve member
8 to the shaft 7. The washer 63 has an axially upward projection
which abuts against the valve member 8. An outer portion of the
valve member 8 and an outer portion of the washer 63 are axially
spaced from each other by a gap of a predetermined size (a predetermined
thickness) which enables the valve member 8 to deform and hence
contact a complete circle of the valve seat 16 even if the valve
member 8 tilts.
[0056] The diaphragm 9 forms a thin-film sealing member. The diaphragm
9 extends around the shaft 7. In FIG. 3, the diaphragm 9 is located
above the central projection 62 of the shaft 7. An inner portion
of the diaphragm 9 is held between the lower end of the moving core
53 and a step on the shaft 7. Thus, the diaphragm 9 is mounted on
the shaft 7. The diaphragm 9 is made of rubber-based resilient material
such as NBR (nitrile-butadiene rubber). The diaphragm 9 airtightly
or fluidtightly partitions a portion of the controlled-fluid passage
10 into the first control chamber 11 and the second control chamber
12. During the change of the solenoid valve 1 to its closed state,
the diaphragm 9 enables the valve member 8 to gently contact the
valve seat 16 while adjusting the pressure balance between the first
control chamber 11 and the second control chamber 12.
[0057] An outer circumferential edge of the diaphragm 9 fits on
the engagement walls 19 of the tubular member 3. The outer circumferential
edge of the diaphragm 9 is held between the engagement walls 19
of the tubular member 3 and a lower end of the plate magnetic 52.
The held portion of the diaphragm 9 presses the plate magnetic 52
against the yoke 51 and the bobbin 5. A central portion of the diaphragm
9 forms a circular connection portion 64 extending around the shaft
7. The connection portion 64 of the diaphragm 9 is attached to the
shaft 7. Specifically, the connection portion 64 of the diaphragm
9 is held between the lower end of the moving core 53 and the step
on the shaft 7. The diaphragm 9 has an easily deformable portion
65 which extends outward from the connection portion 64. The thickness
of the connection portion 64 is greater than that of the easily
deformable portion 65. Therefore, the connection portion 64 is harder
than the easily deformable portion 65. The shaft 7 is inserted through
a central hole of the connection portion 64 by a pressing process.
Thus, the shaft 7 and the connection portion 64 of the diaphragm
9 are fixed to each other.
[0058] In FIG. 3, the walls 27 of the closed upper end of the housing
2 have a through hole 70 with a width of, for example, 4 mm. The
hole 70 allows the flow of air between the second control chamber
12 and the interior of the pipe 23 (the controlled-fluid passage
22). A water repellent filter 71 located in the pipe 23 covers an
end of the hole 70. The water repellent filter 71 prevents water
or other foreign substances from entering the second control chamber
12. Air can pass through the water repellent filter 71.
[0059] The bobbin 5 is formed with an orifice 72 having a width
of, for example, 0.8 mm. The effective cross-sectional area of the
orifice 72 is smaller than that of the hole 70. The orifice 72 allows
a low-rate flow of air into and from the second control chamber
12. An end of the orifice 72 is exposed in the second control chamber
12. As best shown in FIG. 6, a passage 73 in communication with
the orifice 72 is defined between the inner circumferential surfaces
of the tubular member 3 and the outer circumferential surfaces of
the set of the coil 4 and the bobbin 5. The passage 73 has a width
of, for example, 3 mm. The effective cross-sectional area of the
passage 73 is greater than that of the orifice 72. The hole 70 and
the passage 73 are connected by a passage 74 defined between the
stator core 6, the yoke 51, and the upper end walls 27 of the housing
2. The passage 74 has a width of, for example, 3 mm. The effective
cross-sectional area of the passage 74 is greater than that of the
orifice 72.
[0060] The second control chamber 12 includes sub-chambers 75 and
76. The sub-chamber 75 is defined among the diaphragm 9, the moving
core 53, and the plate magnetic 52. The sub-chamber 75 is also referred
to as the diaphragm chamber. In FIG. 3, the sub-chamber 76 is defined
among the inner circumferential surfaces of the bobbin 5, the lower
end of the stator core 6, the upper end of the moving core 53, and
an upper end of the plate magnetic 52. The sub-chamber 76 accommodates
the return spring 54. The sub-chamber 76 is also referred to as
the spring chamber. As best shown in FIGS. 6 and 8, a clearance
77 is provided between the outer circumferential surface of the
moving core 53 and the inner circumferential surface of the plate
magnetic 52 to allow axial slide of the moving core 53 relative
to the plate magnetic 52. The clearance 77 connects the sub-chambers
75 and 76 with each other. The effective cross-sectional area of
the clearance 77 is smaller than that of the orifice 72.
[0061] The solenoid valve 1 operates as follows. A check on the
leak of fuel vapor from the pipes 104 and 105 (see FIG. 2) is started
by feeding electric power to the coil 4 via the terminals 25. When
the coil 4 is fed with electric power (when the coil 4 is energized),
a magnetomotive force is generated so that the solenoid valve 1
moves out of its fully open state (see FIGS. 5 and 6) and the moving
core 53 is attracted toward the stator core 6 against the force
of the return spring 54. At this time, the projection on the moving
core 53 moves into the recess in the stator core 6. Then, the solenoid
valve 1 falls into its closed state (see FIGS. 7 and 8). Specifically,
the shaft 7 and the valve member 8 move together with the moving
core 53 in the upward direction as viewed in FIGS. 5-8. The valve
member 8 contacts the valve seat 16, thereby closing the valve opening
14.
[0062] The diaphragm 9 deforms in accordance with the upward movement
of the shaft 7. The upward movement of the moving core 53, the shaft
7, and the valve member 8, and the deformation of the diaphragm
9 are allowed by contraction of the diaphragm chamber 75 and the
spring chamber 76 (the second control chamber 12), that is, escape
of air therefrom. During the upward movement of the moving core
53 from its lowermost position as viewed in FIGS. 5-8, air escapes
from the spring chamber 76 to the controlled-fluid passage 22 through
the orifice 72, the passage 73, the passage 74, the hole 70, and
the water repellent filter 71. The rate of escape of air from the
spring chamber 76 is limited by the orifice 72. Therefore, air slowly
escapes from the spring chamber 76, and the rate of a drop in the
pressure within the spring chamber 76 is relatively low. As the
diaphragm 9 deforms, air is driven from the diaphragm chamber 75
into the spring chamber 76 through the clearance 77. The rate of
flow of air from the diaphragm chamber 75 into the spring chamber
76 is limited by the clearance 77. The effective cross-sectional
area of the clearance 77 is smaller than that of the orifice 72.
Therefore, air very slowly moves out of the diaphragm chamber 75.
The rate of a drop in the pressure within the diaphragm chamber
75 can be lower than that of a drop in the pressure within the spring
chamber 76. Thus, air escapes from the second control chamber 12
at a low rate so that the diaphragm 9 slowly deforms upward from
its lowermost position as viewed in FIGS. 5-8. The connection portion
(the central portion) 64 of the diaphragm 9 is less deformable than
the easily deformable portion 65 thereof which extends around the
connection portion 64. Accordingly, the moving core 53, the shaft
7, and the valve member 8 slowly move upward as viewed in FIGS.
5-8. As a result, the valve member 8 gently contacts the valve seat
16 (see FIGS. 7 and 8). Thus, it is possible to effectively suppress
the level of noise generated when the valve member 8 meets the valve
seat 16.
[0063] After the check on the leak of fuel vapor from the pipes
104 and 105 (see FIG. 2) is completed, the feed of electric power
to the coil 4 is suspended. The magnetomotive force disappears upon
the suspension of the electric power feed to the coil 4. Accordingly,
the force of the return spring 54 moves the moving core 53, the
shaft 7, and the valve member 8 downward as viewed in FIGS. 5-8.
Thus, the valve member 8 separates from the valve seat 16, thereby
unblocking the valve opening 14. In this way, the solenoid valve
1 is changed from its closed state to its open state.
[0064] In the case where the vehicular engine is operating and
the solenoid valve 1 remains in its open state, when the purge valve
107 is opened, the canister 102 is subjected to a vacuum generated
by the vehicular engine (see FIG. 2). The vacuum causes an atmosphere
to be drawn into the canister 102 via the controlled-fluid passage
22, the first control chamber 11 (the hole 17), the valve opening
14, the controlled-fluid passage 21, and the pipe 109. The atmosphere
is further drawn from the canister 102 into the engine air passage
103 via the pipe 15 and the purge valve 107. At this time, the atmosphere
carries fuel vapor from the canister 102 to the engine air passage
103.
[0065] The diaphragm 9 deforms in accordance with the downward
movement of the shaft 7. The downward movement of the moving core
53, the shaft 7, and the valve member 8, and the deformation of
the diaphragm 9 are allowed by expansion of the diaphragm chamber
75 and the spring chamber 76 (the second control chamber 12), that
is, introduction of air thereinto. During the downward movement
of the moving core 53 from its uppermost position as viewed in FIGS.
5-8, air flows into the spring chamber 76 from the controlled-fluid
passage 22 through the water repellent filter 71, the hole 70, the
passage 74, the passage 73, and the orifice 72. The rate of flow
of air into the spring chamber 76 is limited by the orifice 72.
Therefore, air slowly enters the spring chamber 76, and the rate
of a rise in the pressure within the spring chamber 76 is relatively
low. As the diaphragm 9 deforms, air is drawn from the spring chamber
76 into the diaphragm chamber 75 through the clearance 77. The rate
of flow of air from the spring chamber 76 into the diaphragm chamber
75 is limited by the clearance 77. The effective cross-sectional
area of the clearance 77 is smaller than that of the orifice 72.
Therefore, air very slowly flows into the diaphragm chamber 75.
The rate of a rise in the pressure within the diaphragm chamber
75 can be lower than that of a rise in the pressure within the spring
chamber 76. Thus, air flows into the second control chamber 12 at
a low rate so that the diaphragm 9 slowly deforms downward from
its uppermost position as viewed in FIGS. 5-8. The connection portion
(the central portion) 64 of the diaphragm 9 is less deformable than
the easily deformable portion 65 thereof which extends around the
connection portion 64. Accordingly, the moving core 53, the shaft
7, and the projection 63 on the shaft 7 slowly move downward as
viewed in FIGS. 5-8. As a result, the central projection 62 on the
shaft 7 gently contacts the shaft supports 15. Thus, it is possible
to effectively suppress the level of noise generated when the central
projection 62 on the shaft 7 meets the shaft supports 15.
[0066] When the supply of fuel into the fuel tank 101 is required,
a filler cap is removed from a filler neck on the fuel tank 101
(see FIG. 2). Therefore, air enters the fuel tank 101 via the filler
neck, and then flows from the fuel tank 101 into the canister 102
via the pipe 104. Provided that the solenoid valve 1 is in its open
state, the air returns from the canister 102 to an exterior through
the pipe 109, the controlled-fluid passage 21, the valve opening
14, the first control chamber 11 (the hole 17), and the controlled-fluid
passage 22.
[0067] The solenoid valve 1 provides advantages as follows. During
the change of the solenoid valve 1 to its closed state, the valve
member 8 gently contacts the valve seat 16 while the pressure balance
between the first control chamber 11 and the second control chamber
12 is suitably adjusted. Therefore, it is possible to suppress the
level of noise when the valve member 8 meets the valve seat 16.
During the change of the solenoid valve 1 to its open state, the
central projection 62 on the shaft 7 gently contacts the shaft supports
15 while the pressure balance between the first control chamber
11 and the second control chamber 12 is suitably adjusted. Therefore,
it is possible to suppress the level of noise when the central projection
62 on the shaft 7 meets the shaft supports 15.
[0068] The connection portion (the central portion) 64 of the diaphragm
9 is attached to the shaft 7. The connection portion 64 of the diaphragm
9 is less deformable than the easily deformable portion 65 thereof
which extends around the connection portion 64. The moving core
53 is supported by the diaphragm 9. The connection portion 64 of
the diaphragm 9 prevents unwanted deformation of the diaphragm 9
while suitably maintaining the pressure balance between the first
control chamber 11 and the second control chamber 12.
[0069] The diaphragm 9 airtightly or fluidtightly separates the
controlled-fluid passage 10 and the second control chamber 12 from
each other. Thus, the diaphragm 9 provides airtight or fluidtight
separation of the electromagnetic drive unit, the plate magnetic
52, and the moving core 53 from the controlled-fluid passage 10.
Accordingly, the diaphragm 9 can avoid the exposure of the electromagnetic
drive unit (including the coil 4), the plate magnetic 52, and the
moving core 53 to water or other foreign substances in air coming
from the controlled-fluid passage 10. Therefore, it is possible
to prevent the occurrence of the short circuit of the coil 4, the
rust on the coil 4, and the defective slide between the plate magnetic
52 and the moving core 53 which might be caused by water or other
foreign substances.
[0070] When the solenoid valve 1 is changed to its open state,
the shaft supports 15 act as the stoppers 47 for the shaft 7. In
addition, the shaft supports 15 can suppress unwanted tilt of the
shaft 7. Accordingly, during the change of the solenoid valve 1
to its closed position, the valve member 8 contacts the valve seat
16 while being prevented from tilting. Thus, the valve opening 14
can surely be closed, and a leakage through the solenoid valve 1
can be prevented.
[0071] During assembly, the shaft 7 is easily connected with the
tubular member 3. Specifically, the sectoral segments of the central
projection 62 on the shaft 7 are passed through the sectoral portions
of the valve opening 14, respectively (see FIG. 10). Then, the shaft
7 is rotated relative to the valve opening 14 by a predetermined
angle. As a result, the central projection 62 thereon can engage
the shaft supports 15 on the tubular member 3. In addition, separation
of the shaft 7 from the tubular member 3 can be prevented. The shaft
supports 15 and the tubular member 3 are integral with each other.
Second Embodiment
[0072] A second embodiment of this invention is similar to the
first embodiment thereof except for a design change indicated below.
A solenoid valve 1 in the second embodiment of this invention is
used in an auxiliary apparatus or an air conditioner for a vehicle.
Third Embodiment
[0073] A third embodiment of this invention is similar to the first
or second embodiment thereof except for a design change indicated
below. The third embodiment of this invention uses gas, gas-phase
coolant, liquid, liquid-phase coolant, or gas-liquid two-phase fluid
instead of air.
Fourth Embodiment
[0074] A fourth embodiment of this invention is similar to one
of the first to third embodiments thereof except for a design change
indicated below. In a solenoid valve 1 of the fourth embodiment
of this invention, a central projection 62 on a shaft 7 is provided
with a cushion rubber ring. When the solenoid valve 1 assumes its
open state, the cushion rubber ring on the central projection 62
contacts shaft supports 15.
Fifth Embodiment
[0075] A fifth embodiment of this invention is similar to one of
the first to fourth embodiments thereof except for design changes
indicated below. In the fifth embodiment of this invention, the
shapes of a valve opening 14 and shaft supports 15 are ones of a
combination of triangles, a combination of rectangles, a polygon,
a combination of ellipses, and a circle.
Sixth Embodiment
[0076] A sixth embodiment of this invention is similar to one of
the first to fifth embodiments thereof except for a design change
indicated below. In a solenoid valve 1 of the sixth embodiment of
this invention, portions of shaft supports 15 are narrower as the
portions move from the bases of the shaft supports 15 toward the
distal ends thereof.
Seventh Embodiment
[0077] A seventh embodiment of this invention is similar to one
of the first to sixth embodiments thereof except for a design change
indicated below. In a solenoid valve 1 of the seventh embodiment
of this invention, shaft supports 15 are provided with reinforcing
ribs.
Eighth Embodiment
[0078] An eighth embodiment of this invention is similar to one
of the first to seventh embodiments thereof except for a design
change indicated below. In a solenoid valve 1 of the eighth embodiment
of this invention, the outside diameter of a central projection
62 on a shaft 7 is greater than the inside diameter of a valve opening
14. When the solenoid valve 1 assumes its open state, the central
projection 62 on the shaft 7 contacts partition walls 13 around
the valve opening 14.
Ninth Embodiment
[0079] FIGS. 12 and 13 show a solenoid valve 201 according to a
ninth embodiment of this invention. In FIG. 12, the solenoid valve
201 is in its open state. In FIG. 13, the solenoid valve 201 is
in its closed state.
[0080] With reference to FIGS. 12 and 13, the solenoid valve 201
includes a tubular or cylindrical housing 214 formed with a fluid
passage 214b therein. A portion of the walls of the housing 214
forms a valve seat 214a defining a part of the fluid passage 214b.
The solenoid valve 201 further includes a solenoid 202, a movable
shaft 211, and a movable valve member 212. The solenoid 202 is supported
within the housing 214. When being energized, the solenoid 202 generates
a magnetomotive force which drives the shaft 211. The valve member
212 is mounted on the shaft 211. The valve member 212 moves together
with the shaft 211. The valve member 212 can contact with and separate
from the valve seat 214a. When the valve member 212 contacts with
the valve seat 214a, the fluid passage 214b is blocked. When the
valve member 212 separates from the valve seat 214a, the fluid passage
214b is unblocked.
[0081] The housing 214 is made of suitable material such as resin
or rubber. The walls of the housing 214 have a radially inward projection
which extends below the solenoid 202, and which is formed with an
annular groove 214c for accommodating an outer circumferential edge
of a diaphragm 216. The outer circumferential surfaces of a lower
end of the housing 214 have an annular groove in which an O-ring
217 fits. The lower end of the housing 214 is connected with an
external pipe (not shown). The O-ring 217 provides airtight or fluidtight
connection between the external pipe and the lower end of the housing
214.
[0082] An upper end of the housing 214 is closed by a cover 218
made of suitable material such as resin or rubber. The cover 218
fits on the upper end of the housing 214. The cover 218 is formed
with a connector portion 218a. A pair of terminals 219 are inserted
into the connector portion 218a. The terminals 219 are fixed to
the connector portion 218a. The cover 218 has a through hole or
a breathing hole 218b for providing communication between an exterior
of the solenoid valve 201 and an interior of an upper portion of
the housing 214. A filter 220 fits on the outer surfaces of the
cover 218, and conceals an upper end of the breathing hole 218b.
The filter 220 prevents water and dust from entering the interior
of the upper portion of the housing 214 via the breathing hole 218b.
The filter 220 is made of synthetic-fiber-based material having
a sufficient air permeability and a high water repellency.
[0083] The solenoid 202 includes a coil 203, a yoke 205, a first
magnetic plate 206, a second magnetic plate 207, a fixed iron core
208, and a movable iron core 209 which compose a magnetic circuit.
The solenoid 202 also includes a bobbin 204 made of resin. The coil
203 is wound on the bobbin 204. The bobbin 204 is fixed by the yoke
205, the first magnetic plate 206, and the second magnetic plate
207. Opposite ends of the coil 203 are electrically connected to
the terminals 219, respectively.
[0084] The yoke 205, the first magnetic plate 206, the second magnetic
plate 207, the fixed iron core 208, and the movable iron core 209
are made of magnetic material. An upper end of the yoke 205 is magnetically
coupled with the fixed iron core 208 and the first magnetic plate
206. A lower end of the yoke 205 is magnetically coupled with the
second magnetic plate 207. The second magnetic plate 207 has an
axially-extending central hole through which the movable iron core
209 slidably extends.
[0085] When electric power is fed to the coil 203 via the terminals
219, magnetic flux is generated in the magnetic circuit formed by
the yoke 205, the first magnetic plate 206, the second magnetic
plate 207, the fixed iron core 208, and the movable iron core 209.
The magnetic flux causes a magnetically-induced attraction force
acting between the fixed iron core 208 and the movable iron core
209. Therefore, the movable iron core 209 is moved upward (toward
the fixed iron core 208). As will be made clear later, the upward
movement of the movable iron core 209 is limited by the valve seat
214a on the walls of the housing 214. On the other hand, downward
movement of the movable iron core 209 is limited by a stopper 215
indicated later.
[0086] An end (a lower end) of the fixed iron core 208 which axially
faces the movable iron core 209 has a tapered recess 208a of an
inverted V shape cross-section. The fixed iron core 208 has an engagement
portion 208b at a deepest part of the recess 208a. The engagement
portion 208b accommodates and holds an upper end of a spring 210
which will be indicated later.
[0087] The movable iron core 209 coaxially extends below the fixed
iron core 208. The movable iron core 209 coaxially faces the fixed
iron core 208. The movable iron core 209 has an axially-extending
central hole into which the shaft 211 extends. The shaft 211 is
fixed to the movable iron core 209. The shaft 211 is made of nonmagnetic
material. An end (an upper end) of the movable iron core 209 which
faces the fixed iron core 208 has a tapered projection 209a basically
conforming to the recess 208a in the fixed iron core 208.
[0088] The spring 210 is provided between the fixed iron core 208
and the movable iron core 209. An upper end of the spring 210 abuts
against the engagement portion 208b of the stator iron core 208.
A lower end of the spring 210 abuts against a flange 211c formed
on an exposed upper end of the shaft 211. The spring 210 urges the
shaft 211 and the movable iron core 209 in a direction away from
the fixed iron core 208.
[0089] As previously mentioned, the shaft 211 is fixed to the movable
iron core 209. Therefore, the shaft 211 moves upward and downward
together with the movable iron core 209. A lower portion of the
shaft 211 has a flange 211a, and an axial projection 211b extending
coaxially and downward from the flange 211a. The valve member 212
has a central aperture through which the projection 211b of the
shaft 211 extends. A fixing member 213 mounted on the projection
211b presses the valve member 212 against the flange 211a, thereby
securing the valve member 212 to the shaft 211.
[0090] During assembly, the valve member 212 is placed around the
projection 211b of the shaft 211. Then, the fixing member 213 is
fitted on the projection 211b by a pressing process. The fixing
member 213 is adjusted so as to press the valve member 212 against
the flange 211a on the shaft 211.
[0091] The outer circumferential surface of a portion of the shaft
211 between the movable iron core 209 and the flange 211 a has an
annular groove 211d into which an inner circumferential edge of
the diaphragm 216 fits.
[0092] The stopper 215 is made of non-magnetic material. The stopper
215 has a central aperture through which the shaft 211 extends.
The stopper 215 separates radially outward from the shaft 211. An
outer portion of the stopper 215 is held among the yoke 205, the
second magnetic plate 207, and a step on the walls of the housing
214. An inner portion of the stopper 215 forms an engagement portion
215a which the lower end of the movable iron core 209 can meet.
The engagement portion 215a limits movement of the movable iron
core 209 away from the fixed iron core 208. As previously mentioned,
the outer circumferential edge of the diaphragm 216 fits into the
groove 214c in the walls of the housing 214. The groove 214c extends
at the step on the walls of the housing 214. The outer circumferential
edge of the diaphragm 216 is held between the stopper 215 and the
step on the walls of the housing 214.
[0093] As previously mentioned, the inner circumferential edge
of the diaphragm 216 fits into the annular groove 211d of the shaft
211. Thus, the inner circumferential edge of the diaphragm 216 is
supported by the shaft 211. As previously mentioned, the outer circumferential
edge of the diaphragm 216 is held between the stopper 215 and the
step on the walls of the housing 214. The diaphragm 216 provides
airtight or fluidtight separation between the fluid passage 214b
in the housing 214 and a portion of the interior of the housing
214 which contains the solenoid 202. The diaphragm 216 is made of
flexible and easily-deformable material such as rubber. The diaphragm
216 allows movement of the shaft 211 (that is, movement of the movable
iron core 209).
[0094] The valve member 212 is made of, for example, rubber. The
valve member 212 is of, for example, a disk shape. The valve member
212 has the central aperture for accommodating the shaft 211.
[0095] The fixing member 213 includes a snap washer of a ring shape
or a disk shape. The fixing member 213 has an outside diameter approximately
equal to that of the valve member 212. The fixing member 213 is
formed with an annular projection 213b extending axially toward
the valve member 212 and having flat top surfaces. The flat top
surfaces of the projection 213b of the fixing member 213 abut against
the valve member 212. The projection 213b of the fixing member 213
forms an engagement portion for supporting the valve member 212.
A portion of the fixing member 213 which extends outward of the
engagement portion 213b is thinner than the rest of the fixing member
213. The outer side surfaces of the engagement portion (the projection)
213b provide a step 213a by which the outer portion of the fixing
member 213 is spaced from a corresponding outer portion of the valve
member 212. Thus, a gap D of a predetermined dimension (a predetermined
thickness) extends between the outer portion of the valve member
212 and the outer portion of the fixing member 213.
[0096] The solenoid valve 201 is assembled as follows. The solenoid
202 except the movable iron core 209 is pre-assembled by suitable
steps. The leads of the coil 203 are electrically connected to the
terminals 219 on the cover 218 by a fusing process. Subsequently,
the spring 210 and the movable iron core 209 are inserted into the
solenoid 202. At this time, one end of the spring 210 is brought
into contact with the engagement portion 208b of the fixed iron
core 208. The other end of the spring 210 is brought into contact
with the flange 211c of the shaft 211. It should be noted that the
shaft 211 is previously attached to the movable iron core 209. The
outer circumferential edge of the diaphragm 216 is fitted into the
annular groove 214c in the walls of the housing 214. Thereafter,
the stopper 215 is placed in the housing 214. Subsequently, the
solenoid 202 which holds the movable iron core 209 and the spring
210 is inserted into the housing 214 from above as viewed in FIGS.
12 and 13. At this time, the lower end surface of the movable iron
core 209 is brought into contact with the stopper 215, and the inner
circumferential edge of the diaphragm 216 is fitted into the groove
211d in the shaft 211. The cover 218 and the housing 214 are fixed
to each other by, for example, a thermally welding process.
[0097] The valve member 212 is placed on the projection 211b of
the shaft 211. The valve member 212 is brought into contact with
the flange 211a of the shaft 211. Then, the fixing member 213 is
placed on the projection 211b of the shaft 211. The fixing member
213 is set so as to press the valve member 212 against the flange
211a of the shaft 211. At this time, the engagement portion 213b
of the fixing member 213 abuts against the valve member 212. In
this way, assembling the solenoid valve 201 is completed.
[0098] The solenoid valve 201 operates as follows. When power feed
to the coil 203 is absent as shown in FIG. 12, the spring 210 holds
the movable iron core 209 in contact with the stopper 215. At this
time, the valve member 212 is separate from the valve seat 214a
so that the fluid passage 214b is unblocked.
[0099] When electric power is fed to the coil 203, magnetic flux
is generated by the coil 203. The magnetic flux flows in a closed
magnetic circuit composed of the yoke 205, the first magnetic plate
206, the movable iron core 209, the fixed iron core 208, and the
second magnetic plate 207. Therefore, the movable iron core 209
and the shaft 211 are moved toward the fixed iron core 208 against
the force of the spring 210. As a result, the valve member 212 comes
into contact with the valve seat 214a, and hence the fluid passage
214b is blocked (see FIG. 13). As the valve member 212 is pressed
against the valve seat 214a, an outer portion of the valve member
212 deforms downward in FIG. 13. The gap D between the outer portion
of the valve member 212 and the outer portion of the fixing member
213 which occurs under normal conditions allows the downward deformation
of the valve member 212. The outer portion of the valve member 212
reaches the outer portion of the fixing member 213, and then further
deforms downward together with the outer portion of the fixing member
213. The thinness of the outer portion of the fixing member 213
allows the downward fixing member 213. Therefore, the solenoid valve
201 is composed of a small number of parts.
Tenth Embodiment
[0100] FIG. 14 shows a portion of a solenoid valve 201A according
to a tenth embodiment of this invention. The solenoid valve 201A
of FIG. 14 is similar to the solenoid valve 201 of FIGS. 12 and
13 except for design changes indicated below.
[0101] In the solenoid valve 201A of FIG. 14, a fixing member 213
except its innermost portion has a flat surface opposing a valve
member 212. An outer portion of the fixing member 213 is thinner
than the rest of the fixing member 213. A surface of the valve member
212 which opposes the fixing member 213 has a step 212a by which
an outer portion of the valve member 212 is spaced from a corresponding
outer portion of the fixing member 213. Thus, a gap D of a predetermined
dimension (a predetermined thickness) extends between the outer
portion of the valve member 212 and the outer portion of the fixing
member 213.
[0102] The solenoid valve 201A of FIG. 14 provides advantages similar
to those given by the solenoid valve 201 of FIGS. 12 and 13.
[0103] It should be noted that the whole of the fixing member 213
may be uniform in thickness.
Eleventh Embodiment
[0104] FIG. 15 shows a portion of a solenoid valve 201B according
to an eleventh embodiment of this invention. The solenoid valve
201B of FIG. 15 is similar to the solenoid valve 201 of FIGS. 12
and 13 except for design changes indicated below.
[0105] In the solenoid valve 201B of FIG. 15, a thin plate 221
and a snap washer 222 fit on a projection 211b of a shaft 211. The
thin plate 221 extends between the snap washer 222 and a valve member
212. The thin plate 221 is made of metal or resin. The thin plate
221 is resilient. The snap washer 222 presses the thin plate 221
against the valve member 212, thereby thrusting the valve member
212 against a flange 211a on the shaft 211.
[0106] A surface of the valve member 212 which opposes the thin
plate 221 has a step 212a by which an outer portion of the valve
member 212 is spaced from a corresponding outer portion of the thin
plate 221. Thus, a gap D of a predetermined dimension (a predetermined
thickness) extends between the outer portion of the valve member
212 and the outer portion of the thin plate 221. The snap washer
222 has an outside diameter approximately equal to or slightly smaller
than that defined by the step 212a on the valve member 212. Preferably,
the snap washer 222 extends inward of an area defined by the step
212a.
[0107] Upon the change of the solenoid valve 201B to its closed
state, the valve member 212 meets a valve seat 214a. As the valve
member 212 is pressed against the valve seat 214a, an outer portion
of the valve member 212 deforms downward in FIG. 15. The gap D between
the outer portion of the valve member 212 and the outer portion
of the thin plate 221 which occurs under normal conditions allows
the downward deformation of the valve member 212. The outer portion
of the valve member 212 reaches the outer portion of the thin plate
221, and then further deforms downward together with the outer portion
of the thin plate 221. The resiliency of the thin plate 2221 allows
the downward deformation of the valve member 212 and the thin plate
221. The downward deformation of the valve member 212 absorbs a
shock thereon which occurs when the valve member 212 meets the valve
seat 214a. Thus, it is possible to reduce the level of noise generated
when the valve member 212 meets the valve seat 214a.
[0108] In addition, reliable airtight contact or reliable fluidtight
contact between the valve member 212 and the valve seat 214a is
provided when the solenoid valve 201B assumes its closed state.
[0109] It should be noted that the step 212a may be omitted from
the valve member 212. In this case, the whole of the lower surface
of the valve member 212 contacts the thin plate 221. |