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Patent Abstract
According to the present invention, a cylindrical member of a solenoid
valve is provided with a protruding portion that protrudes in an
axial direction of the cylindrical member. By fitting the protruding
portion into a vertical groove of a plunger, it is possible to restrict
the cylindrical member from moving in a peripheral direction of
the plunger. Therefore, it is possible to prevent change of the
flow path that passes the plunger and the vertical groove, as well
as to prevent variation in a sliding speed of the plunger or the
like. As a result, a fluid pulsation reduction effect is obtained.
Patent Claims
What is claimed is:
1. A solenoid valve comprising: a sleeve formed in a cup-like shape
having a cylindrical portion and a bottom face, with one end side
of the sleeve being an opening portion; a coil provided on an outer
periphery of the sleeve; a plunger that is housed in the sleeve
and for performing a sliding movement in the sleeve by applying
current to the coil, wherein the plunger includes a vertical groove
formed on an outer peripheral surface thereof along a sliding direction
and a groove portion that is formed on an outer peripheral surface
of the plunger around an outer periphery thereof; a valve body which
moves in accordance with the sliding movement of the plunger; a
seat valve having a valve seat which the valve body seats on and
separates from, and a communication path that is opened and closed
when the valve seat seats on and separates from the valve seat;
a cylindrical member provided with a communication path having an
orifice that enables fluid to move in a sliding direction of the
plunger is fitted into the groove portion; and a positioning portion
restricting movement of the cylindrical member in a peripheral direction
of the plunger is provided in at least one of the plunger and the
cylindrical member, wherein the cylindrical member is assembled
to the plunger such that the positioning portion aligns the vertical
groove with the communication path having the orifice.
2. The solenoid valve according to claim 1, wherein the cylindrical
member includes a protruding portion that protrudes in an axial
direction of the cylindrical member acting as the positioning portion
at a portion where the orifice is formed and is fitted into the
vertical groove.
3. The solenoid valve according to claim 1, wherein the cylindrical
member includes a protruding portion that protrudes in a radial
direction of the cylindrical member acting as the positioning portion
on an inner peripheral surface thereof, and the plunger has a concave
portion provided in the groove portion, into which the protruding
portion is fitted.
4. The solenoid valve according to claim 1, wherein the cylindrical
member includes a bias cut portion formed by a cut-through portion
for cutting itself, and wherein the bias cut portion is formed in
a shape that inclines toward with respect to the axial direction
of the cylindrical member.
5. The solenoid valve according to claim 1, wherein the cylindrical
member includes a bias cut portion formed by a cut-through portion
for cutting itself, and wherein the bias cut portion is formed in
a stepped shape having a portion that is parallel with a peripheral
direction of the cylindrical member.
6. The solenoid valve according to claim 1, wherein the groove
portion of the plunger includes a side wall face that is not chamfered.
7. A solenoid valve comprising: a sleeve formed in a cup-like shape
having a cylindrical portion and a bottom face, with one end side
of the sleeve being an opening portion; a coil provided on an outer
periphery of the sleeve; a plunger that is housed in the sleeve
and for performing a sliding movement in the sleeve by applying
current to the coil, wherein the plunger includes a vertical groove
formed on an outer peripheral surface thereof along a sliding direction
and a groove portion that is formed on an outer peripheral surface
of the plunger around an outer periphery thereof, a valve body which
moves in accordance with the sliding movement of the plunger; a
seat valve having a valve seat which the valve body seats on and
separates from, and a communication path that is opened and closed
when the valve seat seats on and separates from the valve seat;
and a cylindrical member provided with a communication path having
an orifice that enables fluid to move in a sliding direction of
the plunger is fitted into the groove portion, and wherein the cylindrical
member includes a bias cut portion formed by a cut-through portion
for cutting itself, and wherein the bias cut portion is formed in
a stepped shape having a portion that is parallel with a peripheral
direction of the cylindrical member.
8. The solenoid valve according to claim 1, wherein the orifice
and a portion having a larger flow path area than the orifice are
disposed in series along a flow direction of the fluid in the communication
path having the orifice.
Patent Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is based upon and claims the benefit of
Japanese Patent Application No. 2001-249420 filed on Aug. 20, 2001,
and PCT Application No. PCT/JP02/08150 filed on Aug. 8, 2002 the
content of which are incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to a solenoid valve for which
opening and closing of a flow path is controlled by applying current
to a coil. The present invention is preferably applied, for example,
to a brake fluid pressure control valve disposed in a conduit of
an ABS actuator provided in a vehicular braking apparatus.
RELATED ART OF THE INVENTION
[0003] FIG. 10 is across sectional view of a conventional solenoid
valve J1. In the solenoid valve J1, when current is not applied
to a coil J2, a plunger J4 is urged by elastic force of a spring
J3, and a ball J6 provided at a tip of a shaft J5 that moves together
with the plunger J4 separates from a valve seat J8 of a seat valve
J7. Thus, a conduit A is in an opened state. When current is applied
to the coil J2, the plunger J4 is urged in resistance to the elastic
force of the spring J3, and the ball J6 provided at the tip of the
shaft J5 is seated on the valve seat J8 of the seat valve J7. Accordingly,
the conduit A is in a closed state. Further, a vertical groove J9
that is parallel with a sliding direction of the plunger J4 is formed
on the outer periphery of the plunger J4. Movement of fluid through
the vertical groove J9 facilitates sliding of the plunger J4.
[0004] In the type of solenoid valve J1, when the conduit A is
opened and closed quickly, fluid pulsation becomes more substantial
and thus problems such as an abnormal noise occur. Accordingly,
a groove portion J10 is provided on an outer periphery of the plunger
J4, and a ring shaped member J11 made of a resin is disposed in
the groove portion J10. An orifice (fluid throttle) J12 that communicates
with the vertical groove J9 is provided in the groove portion J10,
and thus, a sliding speed of the plunger J4 becomes slower and a
fluid pulsation reduction effect is obtained.
[0005] In the above mentioned configuration, since the ring shaped
member J11 is assembled arbitrarily, there are cases in which relative
displacement of the orifice J12 and the vertical groove J9 is generated,
making it difficult to ensure a flow path. Therefore, in order to
ensure the flow path, a chamfered portion J13 is provided such that
a side wall face of the groove portion J10 is tapered, and the fluid
is allowed to pass through the chamfered portion J13.
[0006] In the aforementioned conventional solenoid valve J1, relative
displacement of the orifice J12 and the vertical groove J9 is generated
by arbitrary assembly of the ring shaped member J1. The relative
displacement, as shown in FIGS. 11A and 11B, changes the flow path
(as shown by arrows in the drawing) of the fluid that passes the
orifice J12 and the vertical groove J9, causing variation in flow
path resistance. In such a case, variation in the sliding speed,
or the like, of the plunger J4 occurs, and thus it is no longer
possible to obtain sufficient fluid pulsation reduction effect.
[0007] Moreover, if the flow path is ensured by providing the chamfered
portion J13 on the groove portion J10, a cross sectional area D
of a portion of the plunger J4 at which the chamfered portion J13
is provided becomes smaller. Accordingly, attraction force is reduced.
[0008] Further, assembly of the ring shaped member J11 to the plunger
J4 is executed by press-expanding the ring shaped member J11 using
a bias cut portion (a cut-through portion) , not shown, which is
formed in the ring shaped member J11. However, fluid leaks through
the bias cut portion, and thus the sliding speed of the plunger
J4 deviates from a required set value.
DISCLOSURE OF THE INVENTION
[0009] It is therefore an object of the present invention to provide
a solenoid valve that is capable of obviating the above problems.
[0010] It is an object of the present invention to eliminate variation
in the flow path resistance caused by arbitrary assembly of a ring
shaped member having an orifice, and to ensure sufficient fluid
pulsation reduction effect.
[0011] It is further object of the present invention to ensure
a cross sectional area of a plunger to prevent decrease in attraction
force.
[0012] Moreover, it is object of the present invention to prevent
fluid leakage through a bias cut portion.
[0013] According to the present invention, a solenoid valve includes
a vertical groove formed along a sliding direction of a plunger,
a groove portion that is formed around an outer periphery of the
plunger are provided on an outer peripheral surface of the plunger,
a cylindrical member provided with a communication path having an
orifice that allows fluid to move in a sliding direction of the
plunger is fitted into the groove portion, a positioning portion
restricting movement of the cylindrical member in a peripheral direction
of the plunger is provided in at least one of the plunger and the
cylindrical member, and the cylindrical member is assembled to the
plunger such that the positioning portion aligns the vertical groove
with the communication path having the orifice.
[0014] Accordingly, the positioning portion is able to align the
vertical groove with the communication path formed by the orifice.
Therefore, it is possible to prevent change of flow path that passes
the orifice and the vertical groove of the plunger, and variation
in a sliding speed of the plunger. As a result, it is possible to
obtain sufficient fluid pulsation reduction effect.
[0015] A solenoid valve according to the present invention may
be provided with, for example, a protruding portion that protrudes
in an axial direction of the cylindrical member at a portion of
the cylindrical member where the orifice is formed. This protruding
portion serves as the positioning portion. By fitting the protruding
portion into the vertical groove, it is possible to align the vertical
groove with the communication path having the orifice.
[0016] Alternatively, a solenoid valve according to the present
invention may be provided with a protruding portion that protrudes
in a radial direction of the cylindrical member at an inner peripheral
surface of the cylindrical member. The protruding portion serves
as the positioning portion. A concave portion into which the protruding
portion is fitted is provided in the groove portion. By fitting
the protruding portion into the concave portion, it is possible
to align the vertical groove and the communication path having the
orifice.
[0017] A solenoid valve according to the present invention may
be characterized in that a bias cut portion formed by a cut-through
portion that divides the cylindrical member is formed in the cylindrical
member. This bias cut portion is formed in a shape that inclines
toward with respect to the axial direction of the cylindrical member.
Such a construction allows the bias cut portion to be lengthened,
and thus a flow resistance of the fluid becomes larger at the bias
cut portion. Therefore, it is possible to inhibit fluid leakage
through the bias cut portion.
[0018] A solenoid valve according to the present invention may
be characterized in that a bias cut portion formed by a cut-through
portion that divides the cylindrical member is formed in the cylindrical
member. The bias cut portion is formed in a stepped shape having
a portion that is parallel with a peripheral direction of the cylindrical
member. In such a construction, even if the cylindrical member expands
in the radial direction, the portion parallel with the peripheral
direction of the cylindrical member of the bias cut portion shuts
off the flow path at the bias cut portion. Accordingly, it is possible
to prevent fluid leakage through the bias cut portion.
[0019] A solenoid valve according to the present invention may
be characterized in that a side wall face of the groove portion
of the plunger is not chamfered. In this case, however, some cases
where chamfering of approx. 0.1 to 0.2 mm is allowed to remove burrs,
or the like. Accordingly, it is possible to ensure a large cross
sectional area of the plunger and prevent decrease in attraction
force.
[0020] A solenoid valve according to the present invention may
be characterized in that the orifice and a portion having a larger
flow path area than the orifice are disposed in series along a flow
direction of the fluid in the communication path having the orifice.
[0021] Accordingly, the orifice is shorter and dimensional accuracy
in processing is improved, thereby reducing variation in the flow
path resistance.
[0022] It should be noted that the above reference numerals in
parentheses indicate individual portions. These reference numerals
correspond with specific portions to be described in the later embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Other objects, features and advantages of the present invention
will be understood more fully from the following detailed description
made with reference to the accompanying drawings. In the drawings:
[0024] FIG. 1 is a cross sectional view of a solenoid valve 1 according
to a first embodiment of the present invention;
[0025] FIG. 2 is an enlarged view of a vicinity portion of a cylindrical
member 12 of FIG. 1;
[0026] FIG. 3A is a top view of the cylindrical member 12;
[0027] FIG. 3B is a partial cross sectional view of the cylindrical
member 12 viewed from the front;
[0028] FIG. 3C is a partial cross sectional view of the cylindrical
member 12 viewed from the right side of FIG. 3B;
[0029] FIG. 4 is a bar graph comparing a magnetic force of the
solenoid valve 1 according to the first embodiment of the present
invention and that of a related art solenoid valve J1;
[0030] FIG. 5A is a top view of the cylindrical member 12;
[0031] FIG. 5B is a partial cross sectional view of the cylindrical
member 12 viewed from the front;
[0032] FIG. 5C is a partial cross sectional view of the cylindrical
member 12 viewed from the right side of FIG. 5B;
[0033] FIG. 6A is a top view of the cylindrical member 12;
[0034] FIG. 6B is a partial cross sectional view of the cylindrical
member 12 viewed from the front;
[0035] FIG. 6C is a partial cross sectional view of the cylindrical
member 12 viewed the right side of FIG. 6B;
[0036] FIG. 7A is a top view of the cylindrical member 12;
[0037] FIG. 7B is a partial cross sectional view of the cylindrical
member 12 viewed from the front;
[0038] FIG. 7C is a partial cross sectional view of the cylindrical
member 12 viewed from the right side of FIG. 7B;
[0039] FIG. 8 is a cross sectional view of the solenoid valve 1
according to a fifth embodiment of the present invention;
[0040] FIG. 9A is a top view of the cylindrical member 12;
[0041] FIG. 9B is a partial sectional view viewed from the front;
[0042] FIG. 9C is a partial sectional view of the cylindrical member
12 viewed from the right side of FIG. 9B;
[0043] FIG. 9D is a partial sectional view of the cylindrical member
12 according to another modification of the fifth embodiment;
[0044] FIG. 9E is a partial sectional view of the cylindrical member
12 according to another modification of the fifth embodiment;
[0045] FIG. 10 is a cross sectional view of the related art solenoid
valve J1; and
[0046] FIG. 11 shows a difference of flow paths when a ring shaped
member J11 is displaced.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0047] The present invention will be described further with reference
to various embodiments in the drawings.
(First Embodiment)
[0048] FIG. 1 is a cross sectional view of a solenoid valve 1 according
to a first embodiment of the present invention, and FIG. 2 is a
sectional view taken along line A-A of FIG. 1. The solenoid valve
1 is, for example, disposed in a conduit A for a brake fluid formed
in a housing 2 of an ABS actuator. FIG. 1 shows a state when normal
braking is executed, that is, a state in which current is not applied
to a coil.
[0049] As shown in FIG. 1, the solenoid valve 1 is provided with
a guide 3 made of a magnetic material. The guide 3 is formed in
a stepped cylindrical shape such that a large diameter portion side
of the guide 3 is fitted into a concave portion 4 of the housing
2 of the ABS actuator. Further, a part of the housing 2 is fitted
into a recess provided in the guide 3 by deforming the vicinity
of an opening end of the concave portion 4 of the housing 2, and
thus the guide 3 is fixed to the housing 2.
[0050] The guide 3 includes a guide hole 3a that is positioned
at a small diameter side of the guide 3 and holds a shaft 5 slidably,
a seat insertion hole 3b that is positioned at a large diameter
side of the guide 3 and into which a seat valve 6 is pressed, and
a communication hole 3d for communicating a space 3c surrounded
by the seat valve 6 and the seat insertion hole 3b with the conduit
A formed in the housing 2.
[0051] The shaft 5 is formed of non-magnetic metal (such as stainless
steel). The shaft 5 is shaped so as to be cylindrical, and an end
portion thereof at the side of the seat valve 6 protrudes and extends
from the guide hole 3a into the space 3c. A ball (valve body) 5a
is welded to the tip of the end portion.
[0052] The seat valve 6 is formed in a cylindrical shape. A first
communication path 6a is formed at a central portion in a radial
direction of the seat valve 6 for communicating the space 3c in
the guide 3 to the conduit A formed in the housing 2. Further, a
tapered first valve seat 6b, which the ball 5a of the shaft 5 seats
on and separates from, is formed at an end portion of the first
communication path 6a on the side of the space. Moreover, a second
communication path 6c for communicating the space 3c in the guide
3 to the conduit A is formed in parallel with the first communication
path 6a in the seat valve. A tapered second valve seat 6d which
a spherical check valve 7 seats on and separates from is formed
in the second communication path 6c, at an end portion on the opposite
side to the shaft 5.
[0053] The check valve 7 is held at a position opposite to the
second valve seat 6d by a filter 8 pressed into a side of an end
portion of the seat insertion hole 3b of the guide 3. A filter 9
is also disposed on an outer periphery of the large diameter portion
of the guide 3 so as to surround the communication path 3d. The
filters 8 and 9 prevent foreign matter mixed within the fluid from
entering the solenoid valve 1.
[0054] An outer peripheral side of a small diameter portion of
the guide 3 is fitted into a sleeve 10. The sleeve 10, made of non-magnetic
metal (e.g., stainless steel) , is formed in a cup-like shape having
a cylindrical portion with one end that is open. A bottom face thereof
is substantially spherical. A substantially cylindrical plunger
11 made of a non-magnetic material is disposed at a side of the
bottom face of the sleeve 10, and the plunger 11 is slidable in
the sleeve 10. The plunger 11 contacts the bottom face of the sleeve
10. When the plunger 11 contacts with the bottom face of the sleeve
10, a sliding movement of the plunger 11 in a direction toward the
upper side of the drawing is restricted.
[0055] A vertical groove 11a that is parallel with a sliding direction
of the plunger 11 is formed on an outer peripheral surface of the
plunger 11. Movement of the fluid through the vertical groove 11a
enables the plunger 11 to easily slide in the sleeve 10. A groove
portion 11b running around the outer periphery of the plunger 11
is formed on an outer peripheral surface. A side wall face of the
groove portion 11b is not chamfered, or, if it is slightly chamfered
so that chamfering is only performed to a small portion. The cylindrical
member 12 is disposed in the groove portion 11b.
[0056] FIGS. 3A-3C are a schematic views of the cylindrical member
12. FIG. 3A is a top view of the cylindrical member 12 (viewed from
a top of FIG. 1). FIG. 3B is a partial cross sectional view of the
cylindrical member 12 viewed from the front, and FIG. 3C is a partial
cross sectional view of the cylindrical member 12 viewed from the
right side of FIG. 3B.
[0057] The cylindrical member 12 has a substantially rectangular
cross-section when cut along an axial direction of the plunger 11.
The cylindrical member 12 is thin in a radial direction, and thick
in an axial direction (i.e. a sliding direction of the plunger 11).
Moreover, a longitudinal direction of the cylindrical member 12
is along with the sliding direction of the plunger 11.
[0058] The cylindrical member 12 is made of a resin with a large
coefficient of linear expansion such as 10.times.10.sup.-5/.degree.C.
or more. The cylindrical member 12 is provided with a communication
path 12a that is parallel with a movement direction of the plunger
11, and an orifice 12b disposed in the communication path 12a. The
orifice 12b restricts an amount of the fluid that flows through
the communication path 12a.
[0059] More specifically, the orifice 12b and a portion having
a larger flow path area than the orifice 12b are disposed in series
in the communication path 12a of the cylindrical member 12. Accordingly,
the orifice 12b is made shorter and dimensional accuracy during
processing of the orifice 12b is improved, thereby reducing variation
in the flow path resistance.
[0060] The cylindrical member 12 is provided with protruding portions
12c that protrude at both sides in the axial direction. The protruding
portions 12c are formed on both sides of the flow path which is
formed by the orifice 12b, and this pair of protruding portions
are fitted into the vertical groove 11a of the plunger 11. The width
of the pair of protruding portions 12c, on respective sides, is
the same as the width of the vertical groove 11a, and fitting of
the pair of protruding portions 12c into the vertical groove 11a
defines positioning of the orifice 12b and the vertical groove 11a.
Accordingly, the vertical groove 11a is aligned with the communication
path 12a formed by the orifice 12b.
[0061] Moreover, at a high temperature the cylindrical member 12
has the same length in the sliding direction of the plunger 11 as
the groove portion 11b. At a low temperature, length of the cylindrical
member 12 is smaller than that of the groove portion 11b. Specifically,
it has been confirmed that an amount of gap created between the
cylindrical member 12 and the groove portion 11b in the sliding
direction of the plunger 11 is proportional to a response time of
the solenoid valve 1. Thus, the lengths of the cylindrical member
12 and the groove portion 11b are set such that, at the low temperature,
the amount of gap created between the cylindrical member 12 and
the groove portion 11b is equal to an amount of gap according with
a required response time of the solenoid valve 1.
[0062] Further, as shown in FIG. 3C, a bias cut portion 12d for
dividing the cylindrical member 12 is formed in the cylindrical
member 12, at a position which is different to the position at which
the orifice 12b is formed. By press-expanding the cylindrical member
12 with the bias cut portion 12d, the cylindrical member 12 can
be fitted into the groove portion 11b. The bias cut portion 12d
is formed as a cut-through portion that is inclined with respect
to the axial direction of the cylindrical member 12. It is formed
so as to be longer than in the case the bias cut portion is formed
in parallel with the sliding direction of the plunger 11.
[0063] The shaft 5 is urged to the plunger 11 side by a spring
13 disposed between the shaft 5 and the seat valve 6, and the shaft
5 always abuts against the plunger 11 so as to operate integrally.
Note that the shaft 5 and the plunger 11 configure movable members
that move based on whether or not current is applied to a coil 1.
[0064] A cylindrical spool 15 is disposed around the sleeve 10,
and houses the coil 14 that creates a magnetic field when current
is applied. The spool 15, made of a resin (such as nylon), is formed
by performing a secondary molding subsequent to attaching the coil
14 following a primary molding. A yoke 16 with a cup-like shape
made of a magnetic material is formed on the outer periphery of
the spool 15, and the yoke 16 houses the spool 15 and the coil 14.
An opening portion is formed at a central portion of the bottom
face of the yoke 16, and the bottom face side of the sleeve 10 is
fitted into the opening portion. Terminals, not shown, are retracted
from the coil 14. Current can be applied to the coil 14 through
the terminals.
[0065] At an inlet side of the yoke 16, a ring shaped positioning
member 17 is disposed between the yoke 16 and the large diameter
portion of the guide 3 for positioning the yoke 16 and the guide
3.
[0066] Next, operation of the solenoid valve 1 with the aforementioned
configuration will be described. As mentioned above, FIG. 1 shows
a state of the solenoid valve 1 when current is not applied to the
coil 14. As shown in FIG. 1, when current is not applied to the
coil 14, the shaft 5 and the plunger 11 are urged toward the side
of the bottom face of the sleeve 10 by elastic force of the spring
13, such that the plunger 11 contacts the bottom face of the sleeve
10. Then, the ball 5a of the shaft 5 separates from the first valve
seat 6b of the seat valve 6, and the conduit A is in a communication
state (opened state) through the first communication path 6a, the
space 3c in the guide 3, and the communication hole 3d of the guide
3. Therefore, the solenoid valve 1 is in a communication state when
current is not applied to the coil 14.
[0067] On the other hand, when current is applied to the coil 14,
a magnetic field is created by the coil 14, and a magnetic path
is formed by the guide 3, the plunger 11, the yoke 16 and the ring
member 17. Next, the plunger 11 is attracted toward the guide 3
side by magnetic attraction force, and thus the shaft 5 and the
plunger 11 are moved toward the side of the seat valve 6 resisting
the spring 13. Accordingly, the ball 5a of the shaft 5 is seated
on the first valve seat 6b of the seat valve 6 and the solenoid
valve 1 is placed in a shut-off state (closed state).
[0068] During opening and closing operation of the solenoid valve
1, when the temperature is normal to high, the amount of a gap between
the cylindrical member 12 and the groove portion 11b of the plunger
11 in the sliding direction of the plunger 11 is substantially zero.
Therefore, sliding speed of the plunger is reduced due to a throttling
effect of the orifice 12b formed in the cylindrical member 12. Accordingly,
it is possible to slow down the opening and closing operation of
the conduit A (flow path) by the solenoid valve 1, and a fluid pulsation
reduction effect is obtained.
[0069] On the contrary, when the temperature is low, the gap is
increased between the cylindrical member 12 and the groove portion
11b of the plunger 11 in the sliding direction. Therefore, even
if viscous resistance of the fluid at a low temperature is larger
than that at a normal temperature, the plunger 11 slides easily.
Accordingly, the opening and closing operation of the conduit A
by the solenoid valve 1 is performed at a desired slow speed, that
is, the operation is not executed too slowly. As a result, responsiveness
at a low temperature can be enhanced.
[0070] When performing such the operation with the solenoid valve
1 according to the present embodiment, the protruding portions 12c
provided in the cylindrical member 12 act as a positioning portion
so as to align the vertical groove 11a with the communication path
12a formed by the orifice 12b. Accordingly, of the flow path that
passes through the orifice 12b and the vertical groove 11a of the
plunger his not changed, and it is possible to decrease variation
in a sliding speed, or the like of the plunger 11. As a result,
sufficient fluid pulsation reduction effect is obtained.
[0071] According to the present embodiment, the sidewall face of
the groove portion 11b formed in the plunger 11 is not chamfered,
or, if it is slightly chamfered so that chamfering is only performed
to a small portion. This is achieved because the orifice 12b is
aligned with the vertical groove 11a as mentioned above, and thus
the fluid reliably flows through the orifice 12b even if chamfering
is hardly formed at all. This construction ensures a large cross
sectional area D of the plunger 11. FIG. 4 shows a result of a comparison
between magnetic attraction forces of the solenoid valve 1 according
to the present embodiment and that of the related art chamfered
solenoid valve J1. As is apparent from the result, the solenoid
valve 1 according to the present embodiment satisfies a required
attraction force, thereby preventing decrease in magnetic attraction
force.
[0072] Moreover, since the cylindrical member 12 is formed so as
to be wide according to the present embodiment, it is possible to
ensure that the bias cut portion 12d is long. Accordingly, flow
resistance of the fluid increases through the bias cut portion 12d
and fluid leakage through the bias cut portion 12d is therefore
inhibited. Since the groove portion 11b is not chamfered substantially,
only minimal fluid flow to the bias cut portion 12d through the
chamfered portion is possible. Therefore, fluid leakage through
the bias cut portion 12d is further inhibited.
[0073] Moreover, since the cylindrical member 12 is thin in the
radial direction, flexural rigidity of the cylindrical member 12
is small. Therefore, when the fluid pressure, which is generated
during the plunger 11 slides, acts on the inner peripheral surface
side of the cylindrical member 12, the cylindrical member 12 is
easily deformed such that the outer peripheral surface of the cylindrical
member 12 contacts the inner peripheral surface of the sleeve 10.
Accordingly, the boundary of these two members is reliably sealed.
[0074] If the cylindrical member 12 is made of nylon 6T, polytetrafluoroethylene,
or the like, which has low water absorbing properties, it is possible
to reduce the change in outside dimensions to a minimum, and reduce
the difference in diameter of the cylinder member 12 from the inner
diameter of the sleeve 10. Therefore, leakage from the bias cut
portion 12d is further reduced.
(Second Embodiment)
[0075] FIGS. 5A-5C are schematic views of the cylindrical member
12 according to a second embodiment of the present invention. FIG.
5A is atop view of the cylindrical member 12. FIG. 5B is a partial
cross sectional view of the cylindrical member 12 viewed from the
front. FIG. 5C is a partial cross sectional view of the cylindrical
member 12 viewed from the right side of FIG. 5B. The second embodiment
only differs from the first embodiment in that the cylindrical member
12 has been modified. Since other elements of the solenoid valve
1 are the same as in the first embodiment, only a portion which
is different will be described.
[0076] In the first embodiment, the orifice 12b is formed by the
partially narrowed communication path 12a which is formed in a groove-like
shape on the outer peripheral surface of the cylindrical member
12. On the contrary, according to the second embodiment, the orifice
12b is formed by partially drilling the cylindrical member 12. According
to the second embodiment in which the orifice 12b is formed by drilling,
an effect is obtained that is similar to that of the first embodiment.
(Third Embodiment)
[0077] FIGS. 6A-6C are schematic views of the cylindrical member
12 according to a third embodiment of the present invention. FIG.
6A is a top view of the cylindrical member 12. FIG. 6B is a partial
cross sectional view of the cylindrical member 12 viewed from the
front. FIG. 6C is a partial cross sectional view of the cylindrical
member 12 viewed from the right side of FIG. 6B. The third embodiment
only differs from the first embodiment in that the cylindrical member
12 has been modified. Since other elements of the solenoid valve
1 are the same as in the first embodiment, only a portion which
is different will be described.
[0078] In the first embodiment, the cylindrical member 12 and the
plunger 11 are positioned by the protruding portions 12c that protrude
at both sides in the axial direction of the cylindrical member 12.
On the contrary, according to the third embodiment, a concave portion
is formed in the groove portion 11b of the plunger 11, and the cylindrical
member 12 and the plunger 11 are positioned by fitting a protruding
portion 12e protruding in the radial direction from the inner diameter
side of the cylindrical member 12 into the concave portion in the
groove portion 11b.
[0079] The above configuration also aligns the communication path
12a of the cylindrical member 12 with the vertical groove 11a of
the plunger 11. Accordingly, an effect is obtained that is similar
to that of the first embodiment.
(Fourth embodiment)
[0080] FIGS. 7A-7C are schematic views of the cylindrical member
12 according to a fourth embodiment of the present invention. FIG.
7A is a top view of the cylindrical member 12. FIG. 7B is a partial
cross sectional view of the cylindrical member 12 viewed from the
front. FIG. 7C is a partial cross sectional view of the cylindrical
member 12 viewed from the right side of FIG. 7B. Since the fourth
embodiment only differs from the first embodiment in that the cylindrical
member 12 has been modified. Since other elements of the solenoid
valve 1 are the same as in the first embodiment, only a portion
which is different will be described.
[0081] According to the first embodiment described above, the bias
cut portion 12d is inclined with respect to the axial direction
of the cylindrical member 12. On the contrary, according to the
fourth embodiment, the bias cut portion 12d is formed in a stepped
shape constituted by portions that are parallel with the axial direction
of the cylindrical member 12 and a portion parallel with a peripheral
direction of the cylindrical member 12.
[0082] Accordingly, even if the cylindrical portion 12 expands
in the radial direction, the portion of the bias cut portion 12d
that is parallel with the peripheral direction of the cylindrical
member 12 can shut off the flow path at the bias cut portion 12d,
thereby preventing fluid leakage through the bias cut portion 12d.
[0083] Accordingly, as in the fourth embodiment, forming of the
bias cut portion 12d in the stepped shape constituted by a portion
parallel with the axial direction of the cylindrical member 12 and
the portions parallel with the peripheral direction of the cylindrical
member 12 enables an effect that is similar to that of the first
embodiment to be obtained. Further, preventing fluid leakage through
the bias cut portion 12d is inhibited.
[0084] In the fourth embodiment, an example has been described
in which the shape of the cylindrical member 12 according to the
first embodiment is changed. However, it is also possible to prevent
fluid leakage through the bias cut portion 12d by applying the cylindrical
member 12 according to the fourth embodiment to a conventional solenoid
valve in which a side wall face of the groove portion 11b is chamfered.
[0085] Moreover, as shown in FIG. 7D, the bias cut portion 12d
which is formed in the cylindrical member 12 may have a wide V-shape
such that a direction of the flow path formed by the bias cut portion
12d is changed in middle portion thereof. Since such a configuration
is easy to machine and does not easily permit fluid to flow through,
it is possible to prevent fluid leakage through the bias cut portion
12d.
(Fifth Embodiment)
[0086] FIG. 8 is a cross sectional configuration of the solenoid
valve 1 according to a fifth embodiment of the present invention.
FIG. 9A is a top view of the cylindrical member 12 of FIG. 8. FIG.
9B is a partial cross sectional view of the cylindrical member 12
viewed from the front. FIG. 9C is a partial cross sectional view
of the cylindrical member 12 viewed from the right side of FIG.
9B. Since the fifth embodiment only differs from the first embodiment
in that the plunger 11 and the cylindrical member 12 are modified.
Since other elements of the solenoid valve 1 are the same as in
the first embodiment, only a portion which is different will be
described.
[0087] Unlike the first embodiment in which the cylindrical member
12 is provided with the protruding portions 12c, the cylindrical
member 12 according to the fifth embodiment is not provided with
protruding portions. If protruding portions are not provided as
previously described, there are cases where relative displacement
of the orifice 12b of the cylindrical member 12 and the vertical
groove 11a of the plunger 11 occurs, and thus the flow path cannot
be ensured. To avoid this problem, a chamfered portion 11c is provided
such that the side wall face of the groove portion 11b is tapered,
and thus fluid can flow through the chamfered portion 11c, thereby
ensuring the flow path.
[0088] Moreover, according to the first embodiment, the bias cut
portion 12d is inclined with respect to the axial direction of the
cylindrical member 12. On the contrary, the bias cut portion 12d
of the fifth embodiment is formed in a stepped shape configured
by portions parallel with the axial direction of the cylindrical
member 12 and a portion parallel with the peripheral direction thereof.
[0089] Accordingly, even if the cylindrical portion 12 expands
in the radial direction, the portion of the bias cut portion 12d
that is parallel with the peripheral direction of the cylindrical
member 12 can shut off the flow path at the bias cut portion 12d,
thereby preventing fluid leakage through the bias cut portion 12d.
[0090] Meanwhile, as shown in FIG. 9D, the bias cut portion 12d
which is formed in the cylindrical member 12 may have a wide V-shape
such that a direction of the flow path formed by the bias cut portion
12d is changed in middle portion thereof. Since such a configuration
is easy to machine, and does not easily permit fluid to flow through,
it is possible to prevent fluid leakage through the bias cut portion
12d.
[0091] Moreover, as shown in FIG. 9E, the bias cut portion 12d
may be a stepped shape configured by portions inclines toward the
axial direction of the cylindrical member 12 and a portion parallel
with the peripheral direction of the cylindrical member 12.
[0092] Accordingly, even if the cylindrical portion 12 expands
in the radial direction, the portion of the bias cut portion 12d
that is parallel with the peripheral direction of the cylindrical
member 12 can shut off the flow path at the bias cut portion 12d,
thereby preventing fluid leakage through the bias cut portion 12d.
[0093] (Modification)
[0094] As well as the orifice being positioned at the protruding
portions 12c that act as the positioning portion, the orifice may
be positioned at a position that is 180.degree. around the cylindrical
member 12 with respect to the positioning portion. Alternatively,
if the plunger 11 is chamfered, the orifice may be positioned at
other positions, since a rate of fluid flow that passes along the
flow path including the chamfered portion is kept to constant.
[0095] While the above description is of the preferred embodiments
of the present invention, it should be appreciated that the invention
may be modified, altered, or varied without deviating from the scope
and fair meaning of the following claims.
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