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Patent Abstract
A solenoid valve includes a movable member disposed in a sleeve
for moving in an axial direction, a valve mechanism portion opening
and closing in accordance with axial movement of the movable member
to establish and interrupt fluid communication, a valve chamber
exposed to an end surface of the movable member at the valve mechanism
portion side and the valve mechanism portion, and a damper chamber
exposed to the other end surface of the movable member axially opposite
to the end surface at the valve mechanism portion side. The movable
member is provided with a throttling portion for establishing fluid
communication between the damper chamber and the valve chamber to
introduce operational fluid from the damper chamber to the valve
chamber. The throttling portion is unitary formed on a sliding surface
portion of the movable member.
Patent Claims
What is claimed is:
1. A solenoid valve comprising: a sleeve; a movable member disposed
in the sleeve to move in an axial direction; a valve mechanism portion
that is openable and closable in accordance with axial movement
of the movable member for establishing and interrupting operational
fluid communication across the valve mechanism portion; a valve
chamber exposed to the valve mechanism portion and an end surface
of the movable member at a valve mechanism portion side of the movable
member; a damper chamber exposed to an axially opposite end surface
of the movable member located opposite the end surface at the valve
mechanism portion side; and a throttling portion unitarily formed
on a sliding surface of the movable member to establish fluid communication
between the damper chamber and the valve chamber and introduce the
operational fluid from the damper chamber to the valve chamber.
2. The solenoid valve according to claim 1, wherein the throttling
portion has a predetermined length in an axial direction and is
formed by an arc-shaped recess in the sliding portion that extends
inwardly in a cross-section at a right angle to the axial direction.
3. The solenoid valve according to claim 1, wherein the throttling
portion is formed by plastic forming.
4. The solenoid valve according to claim 1, wherein the sleeve
comprises a first sleeve portion and a second sleeve portion, and
the movable member is comprised of a first movable portion and a
second movable portion.
5. The solenoid valve according to claim 1, wherein the solenoid
valve is a normally open solenoid valve.
6. The solenoid valve according to claim 5, including a solenoid
coil adapted to be energized to cause axial movement of the movable
member.
7. The solenoid valve according to claim 1, wherein the solenoid
valve is a normally closed solenoid valve.
8. The solenoid valve according to claim 7, including a solenoid
coil adapted to be energized to cause axial movement of the movable
member.
9. A solenoid valve for controlling fluid flow between an inlet
and an outlet comprising: a sleeve; an axially movable member disposed
in the sleeve, the axially movable member having a first end surface
at one axial end of the axially movable member and a second end
surface at an axially opposite end of the axially movable member;
a solenoid coil positioned adjacent the sleeve and adapted to be
energized to axially move the axially movable member; a valve mechanism
portion openable and closable in response to axial movement of the
axially movable member for respectively permitting and preventing
fluid communication between the inlet and the outlet; a valve chamber
exposed to the valve mechanism portion and to the first end surface
of the axially movable member; a damper chamber exposed to the second
end surface of the axially movable member; and at least one recess
formed in the axially movable member constituting a throttling portion
establishing fluid communication between the damper chamber and
the valve chamber.
10. The solenoid valve according to claim 9, wherein the at least
one recess constituting the throttling portion is an arc-shaped
recess formed in a sliding surface portion of the axially movable
member.
11. The solenoid valve according to claim 9, wherein the sleeve
comprises a first sleeve portion and a second sleeve portion.
12. The solenoid valve according to claim 9, wherein the axially
movable member is comprised of a first axially movable portion and
a second axially movable portion.
13. The solenoid valve according to claim 9, wherein the solenoid
valve is a normally open solenoid valve.
14. The solenoid valve according to claim 9, wherein the solenoid
valve is a normally closed solenoid valve.
15. The solenoid valve according to claim 9, wherein the at least
one recess includes a pair of recesses formed in the axially movable
member, each recess constituting a throttling portion establishing
fluid communication between the damper chamber and the valve chamber.
16. The solenoid valve according to claim 9, wherein the axially
movable member includes at least one recessed portion positioned
adjacent the at least one recess constituting the throttling portion,
the at least one recessed portion having a greater depth than the
at least one recess constituting the throttling portion.
Patent Description
[0001] This application is based on and claims priority under 35
U.S.C. .sctn. 119 with respect to Japanese Application No. 2000-346450
filed on Nov. 14, 2000, the entire content of which is incorporated
herein by reference.
FIELD OF THE INVENTION
[0002] The present invention generally relates to a solenoid valve.
More particularly, the present invention pertains to a damper mechanism
of a movable member included in a solenoid valve having a valve
mechanism portion which opens and closes in accordance with the
movement of the movable member in the axial direction for establishing
and interrupting the fluid communication.
BACKGROUND OF THE INVENTION
[0003] Known solenoid valves have a valve mechanism which opens
and closes in accordance with the movement of the movable member
in the axial direction for establishing and interrupting fluid communication.
These solenoid valves also include a damper mechanism for slowing
the moving speed of the movable member in the axial direction for
purposes of reducing the noise generated when the solenoid valve
is opened and closed.
[0004] Japanese Patent Laid-Open Publication No. H08-93955 and
Japanese Patent Laid-Open Publication No. H09-502947 disclose a
solenoid valve which includes a movable member disposed in a sleeve
in an axially slidable manner, a valve mechanism for establishing
and interrupting the fluid communication through opening and closing
of the valve in accordance with the movement of the movable member
in the axial direction, a valve chamber exposed to an end surface
of the movable member at a valve mechanism portion side and to the
valve mechanism portion, and a damper chamber exposed to the opposite
end surface of the moveable member. A ring groove is provided on
the external surface of the movable member. The valve chamber and
the damper chamber are sealed in a liquid-tight manner by the cooperation
of a seal ring provided in the ring groove and an internal surface
of the sleeve. The communication between the valve chamber and the
damper chamber is established through a communication bore provided
in the movable member. The operational fluid in the damper chamber
is introduced into the valve chamber via the communication bore.
With the solenoid valve constructed in the manner described above,
because the operational fluid in the damper chamber is introduced
into or discharged from the valve chamber via the communication
bore in accordance with the movement of the movable member when
the movable member is actuated, the moving speed of the movable
member in the axial direction is slowed by a differential pressure
generated when the operational fluid passes through the communication
bore. As explained above, the damper mechanism of the movable member
is structured with the seal ring and the communication bore in the
known solenoid valve.
[0005] However, with this construction of the known solenoid valves,
the seal ring is required for providing the damper mechanism of
the movable member. Further, in order to receive the seal ring,
the ring groove has to be machined on the external surface of the
movable member. This increases the overall cost for the solenoid
valve in terms of the number of parts and the manufacturing cost.
[0006] A need thus exists for a solenoid valve which has a movable
member with damper effects, but which is not as susceptible to the
drawbacks mentioned above.
SUMMARY OF THE INVENTION
[0007] In accordance with one aspect of the invention, a solenoid
valve includes a sleeve, a movable member disposed in the sleeve
to move in an axial direction, a valve mechanism portion that is
openable and closable in accordance with axial movement of the movable
member for establishing and interrupting operational fluid communication
across the valve mechanism portion, a valve chamber exposed to the
valve mechanism portion and an end surface of the movable member
at a valve mechanism portion side of the movable member, and a damper
chamber exposed to an axially opposite end surface of the movable
member located opposite the end surface at the valve mechanism portion
side. A throttling portion is unitarily formed on a sliding surface
of the movable member to establish fluid communication between the
damper chamber and the valve chamber and introduce operational fluid
from the damper chamber to the valve chamber.
[0008] According to another aspect of the invention, a solenoid
valve for controlling fluid flow between an inlet and an outlet
includes a sleeve, an axially movable member disposed in the sleeve
and having a first end surface at one axial end of the axially movable
member and a second end surface at an axially opposite end of the
axially movable member, a solenoid coil positioned adjacent the
sleeve and adapted to be energized to axially move the axially movable
member, a valve mechanism portion openable and closable in response
to axial movement of the axially movable member for respectively
permitting and preventing fluid communication between the inlet
and the outlet, a valve chamber exposed to the valve mechanism portion
and to the first end surface of the axially movable member, and
a damper chamber exposed to the second end surface of the axially
movable member. At least one recess is formed in the axially movable
member and constitutes a throttling portion establishing fluid communication
between the damper chamber and the valve chamber.
BRIEF DESCRIPTION OF THE DRAWING FIGURES
[0009] The foregoing and additional features and characteristics
of the present invention will become more apparent from the following
detailed description considered with reference to the accompanying
drawing figures in which like reference numerals designate like
elements.
[0010] FIG. 1 is a cross-sectional view of a normally closed type
solenoid valve according to a first embodiment of the present invention.
[0011] FIG. 2 is a cross-sectional view of the solenoid valve taken
along the section line II-II in FIG. 1.
[0012] FIG. 3 is an enlarged view of the portion of the solenoid
valve identified as III in FIG. 2.
[0013] FIG. 4 is a cross-sectional view of a normally open type
solenoid valve according to a second embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0014] FIG. 1 illustrates in cross-section a normally closed type
solenoid valve according to a first embodiment of the present invention.
The solenoid valve includes a housing 17 and a sleeve 7 made of
magnetic material having a cylindrical shape. The bottom portion
of the sleeve 7 is inserted into or positioned in a stepped cylindrical
bore 17e of the housing 17 from the open end of the housing 17.
The sleeve 7 and the housing 17 are sealed in a liquid-tight manner
at several places such as a first rivet or engaging portion 7c,
17a, and a second rivet or engaging portion 7d, 17b. The housing
17 is provided with an inlet bore 17c and an outlet bore 17d. The
inlet bore 17c is in communication with a valve chamber 21 in the
sleeve 7 via a filter 23 fixed to the sleeve 17 and a lateral hole
7e in the bottom portion of the sleeve 17. The first rivet or engaging
portion 7c, 17a interrupts or prevents communication between the
inlet bore 17c and the atmosphere. The second rivet or engaging
portion 7d, 17b interrupts or prevents communication between the
inlet bore 17c and the outlet bore 17d.
[0015] A movable member 9 made of magnetic material is inserted
into or positioned in a blind bore of the sleeve 7 in an axially
slidable manner. The slidable movement of the movable member 9 in
the sleeve 7 is defined as follows. Although the external surface
of the movable member 9 and the internal surface of the sleeve 7
which are opposite to each other and positioned in facing relation
are configured to provide a predetermined clearance, the movable
member 9 is inserted into or positioned in the sleeve 7 with the
predetermined clearance that is dimensioned to be sufficiently narrow
to have a substantial sealing function relative to the operational
speed of the movable member 9.
[0016] A valve seat member 25 is press-fitted into an opening end
portion of the sleeve 7. The valve seat member 25 includes a valve
seat 25a that is in communication with the outlet bore 17d of the
housing 17 via a stepped cylindrical bore 25b provided coaxially
with respect to the valve seat member 25. A ball 27 is provided
between the end surface 9e (valve mechanism portion side end surface)
of the movable member 9 and the valve seat 25a. The sleeve 7 is
also provided with a cylindrical bore 7b positioned coaxially with
respect to the blind bore in the sleeve 7 that receives the movable
member 9 and opens to the bottom surface 7a of the bore in the sleeve
7 that receives the movable member 9.
[0017] A spring 13 is also positioned in the cylindrical bore 7b.
The spring 13 biases the movable member 9 towards the valve seat
member 25 side (i.e., in the downward direction of FIG. 1). The
valve mechanism portion side end surface 9e of the movable member
9 pushes the ball 27 downwardly in FIG. 1 by the biasing force of
the spring 13. Thus, the ball 27 contacts the valve seat 25a during
the normal condition. The valve seat 25a, the ball 27, and the valve
mechanism portion side surface 9e of the movable member 9 constitute
or form a valve mechanism portion.
[0018] A ring 11 of magnetic material is provided on the external
periphery of the sleeve 7 towards the bottom surface side of the
sleeve 7 and projects from the housing 17. A cylindrical yoke 1
made of magnetic material covers the ring 11 and the sleeve 7.
[0019] A bobbin 3 made of non-magnetic material for supporting
a solenoid coil 5 is fixedly provided in the yoke 1. A pair of terminals
15 project from the bobbin 3. Each terminal 15 is connected to the
solenoid coil 5 and to a controller (not shown) which controls an
external power source or solenoid valves for exciting the solenoid
coil 5. The solenoid coil 5 is wound around the bobbin 3. The solenoid
coil 5, the yoke 1, the ring 11, the sleeve 7, and the movable member
9 form a magnetic circuit. In the normal condition of the solenoid
valve, a predetermined clearance exists between the bottom surface
7a of the bore in the sleeve 7 and the end surface 9d (upper side
end surface of FIG. 1) of the movable member 9 that is located at
the axially opposite end of the movable member 9 from the valve
mechanism portion side end surface 9e of the movable member 9. This
predetermined clearance corresponds to an operational stroke range
of the movable member 9 and functions as a magnetic gap.
[0020] Further details associated with the movable member 9 can
be seen with reference to FIGS. 2 and 3 as well as FIG. 1. As shown
in FIGS. 1 and 2, the radius (or width-wise dimension) of the valve
mechanism portion side end surface 9e of the movable member 9 is
smaller than the radius (or width-wise dimension) of the end surface
9d. A pair of spaces or recessed portions 9a, each having a U-shaped
cross-section, is formed between the movable member 9 and the inner
surface of the sleeve 7. The spaces or recessed portions 9a are
located opposite to each other in peripheral direction. That is,
the spaces or recessed portions 9a are located diametrically opposite
to one another. The axial length of the spaces or recessed portions
9a is a predetermined length corresponding to the distance or length
from the end surface 9d of the movable member 9 to an axial end
position 9f. The movable member 9 includes a sliding surface portion
9b formed to have a length from the axial end position 9f of the
concave spaces 9a to a predetermined point in the valve mechanism
portion side as depicted in FIG. 1.
[0021] As shown in FIG. 3, a predetermined clearance "h"
is provided between the outer diameter of the sliding surface of
the sliding surface portion 9b and the inner diameter of the sleeve
7. The clearance "h" is determined to be a relatively
narrow value (e.g., on the order of about 30 microns) so that the
sealing function is still achieved, taking into account the operational
speed of the movable member 9 relative to the sleeve 7. Thus, the
spaces or recessed portions 9a and the valve chamber 21 are substantially
sealed by the sliding surface portion 9b of the movable member 9.
[0022] A damper chamber 19 exposed to the end surface 9d of the
movable member 9 is defined by the space enclosed by the internal
surface of the sleeve 7, the spaces or recessed portions 9a, and
the sliding surface 9b of the movable member 9. The valve chamber
21 is exposed to the valve mechanism portion side end surface 9e
of the movable member 9 and the valve mechanism portion, and is
defined by the space enclosed by the internal surface of the sleeve
7, the valve seat member 25, the ball 27, and the sliding surface
portion 9b of the movable member 9.
[0023] As shown in FIGS. 2 and 3, the sliding surface portion 9b
of the movable member 9 is provided with throttling portions 9c.
These throttling portions 9c are integrally formed in a unitary
manner as part of the movable member 9 and are defined by recesses
that are arc-shaped in cross-section in the radial direction at
positions corresponding to the recessed portions or spaces 9a in
the peripheral direction. The throttling portions 9c are parallel
and extend in the axial direction, and have a predetermined length
corresponding to the length of the sliding surface 9b of the movable
member 9. The recessed portions or spaces 9a and the valve chamber
21 are thus in communication substantially only via the two throttling
portions 9c. Accordingly, the operational fluid in the damper chamber
19 is movable to the valve chamber 21 only through the two throttling
portions 9c. In the illustrated embodiment, the recessed portions
or spaced 9a possess a greater depth (i.e., extend farther inwardly)
than the throttling portions 9c as shown in FIGS. 1-3.
[0024] It is preferable that the throttling portions 9c have a
length in the axial direction that is relatively short so that the
damper effects is maintained. When the throttling portions 9c are
excessively long, the throttling portions 9c tend not to function
as an orifice, but rather perform a choke function. In such a case,
the operational fluid may be vulnerable to the influence of viscosity
changes associated with temperature changes of the operational fluid
when passing through the throttling portions 9c. Thus, the damper
effects cannot be uniformly achieved due to the temperature change
of the operational fluid. In contrast, when the length of the throttled
portions 9c is relatively shorter, the operational fluid becomes
less subject to the viscosity change based on the temperature change
of the operational fluid when passing through the throttling portions
9c. Thus, stable damper effects which are less subject to the influence
of temperature changes of the operational fluid can be obtained.
[0025] The movable member 9 can be manufactured, for example, by
drawing a bar to form the spaces or recessed portions 9a, and forming
the sliding surface portion 9b and the throttling portions 9c by
forging. Accordingly, it is not necessary to employ further processes
for manufacturing the movable member 9. In addition, additional
members for sealing the damper chamber and the valve chamber, such
as seal rings, are not required. Thus, the movable member 9 and
overall solenoid valve can be manufactured with less cost.
[0026] The operation of the solenoid valve according to the first
embodiment of the present invention is as follows. When the solenoid
coil 5 is not energized or excited (i.e., the normal condition),
the movable member 9 is biased in the downward direction of FIG.
1 by the biasing force of the spring 13 to push the ball 27 downward.
The ball 27 thus contacts the valve seat 25a, and the valve mechanism
portion interrupts fluid communication between the inlet bore 17c
and the outlet bore 17d. When the solenoid coil 5 is energized or
excited by the controller, the attractive force of the magnet is
generated at the magnetic gap formed between the end surface 9d
of the movable member 9 and the bottom surface 7a of the bore in
the sleeve 7 to thereby move the movable member 9 in the upper direction
of FIG. 1 against the biasing force of the spring 13. Accordingly,
the ball 27 and the valve seat 25a are separated from one another
to establish fluid communication between the inlet bore 17c and
the outlet bore 17d. By energizing (exciting) and stopping energization
(excitement) of the solenoid coil 5, the valve mechanism portion
can control the establishment and interruption of the fluid communication
between the inlet bore 17c and the outlet bore 17d.
[0027] When the movable member 9 is moved, fluid communication
between the damper chamber 19 and the valve chamber 21 is established
substantially only via the throttling portions 9c. Thus, the moving
speed of the movable member 9 in the axial direction can be slowed
by the differential pressure generated when the operational fluid
passes through the throttled portions 9c to generate the damper
effects. Accordingly, by changing the opening dimension of the throttling
portions 9c, the damper effects of the movable member 9 can be appropriately
changed or controlled.
[0028] A solenoid valve according to a second embodiment of the
present invention is illustrated in FIG. 4. A detailed explanation
of the elements and the features associated with the second embodiment
that are the same as or equivalent to elements and features in the
first embodiment shown in FIGS. 1-3 is not repeated. The following
discussion describes differences between the solenoid valve according
to the second embodiment relative to the first embodiment.
[0029] In the solenoid valve according to the second embodiment,
a sleeve includes a first sleeve portion 107 and a second sleeve
portion 131. A shaft 129 is provided between a movable element 109
and the ball 127. The shaft or rod 129 constitutes a first movable
portion and the movable element 109 constitutes a second movable
portion, with the first and second movable portions together forming
a movable member. The valve employed in the second embodiment is
a normally open type solenoid valve rather than the normally closed
type solenoid valve shown in FIG. 1.
[0030] The shaft 129 is engaged by a spring 113 at a stepped portion
129a. The shaft 129 is normally biased upwardly in FIG. 4 by the
biasing force of the spring 113. A valve mechanism portion side
end surface 109e of the movable element 109 contacts the upper side
end surface 129b of the shaft 129. Thus, the movable element 109
is biased upwardly in FIG. 4. In this condition, a magnetic gap
is formed between the valve mechanism portion side end surface 109e
of the movable element 109 and the upper side end surface 131a of
the second sleeve 131.
[0031] The ball 127 is provided between the bottom side end surface
129c (i.e., the valve mechanism portion side end surface of the
movable member) of the shaft 129 and a valve seat 125a. Because
the movable element 109 is biased upwardly in FIG. 4 via the shaft
129 by the biasing force of the spring 113, the ball 127 and the
valve seat 125a are separated to establish fluid communication between
the inlet bore 117c and the outlet bore 117d. When the solenoid
coil 105 is excited or energized, an attractive force resulting
from the magnetic force is generated in the magnetic gap. By virtue
of this, the movable element 109 is attracted and moved downwardly
in FIG. 4, and so the ball 127 is pushed downwardly via the shaft
129 to contact the valve seat 125a to thereby interrupt the fluid
communication between the inlet bore 117c and the outlet bore 117d.
[0032] The valve chamber 121 exposed to the valve mechanism portion
side end surface 109e of the movable element 109 is in fluid communication
with a space 121c exposed to the valve mechanism portion and the
bottom side end surface 129c of the shaft 129 (i.e., the valve mechanism
portion side end surface of the movable member) in FIG. 4 via a
donut or annular shaped space 121b. This space is formed as a clearance
between the internal surface of the second sleeve 131 and the external
surface of the shaft 129. Thus, one valve chamber is formed by the
valve chamber 121, the space 121b, and the space 121c.
[0033] The structure of the movable member 109, the sliding surface
portion 109b, the throttling portions 109c, and the damper chamber
119 of the normally open type solenoid valve of the second embodiment
are the same as the corresponding parts of the normally closed type
solenoid valve according to the first embodiment. Thus, a detailed
explanation of such features is not repeated here.
[0034] As described above, the normally closed type solenoid valve
of the first embodiment and the normally open type solenoid valve
of the second embodiment are advantageous in that the damper mechanism
of the movable member can be relatively easily manufactured with
less cost, thus providing advantages with respect to other known
solenoid valves.
[0035] The principles, preferred embodiments and modes of operation
of the present invention have been described in the foregoing specification.
However, the invention which is intended to be protected is not
to be construed as limited to the particular embodiments disclosed.
Further, the embodiments described herein are to be regarded as
illustrative rather than restrictive. Variations and changes may
be made by others, and equivalents employed, without departing from
the spirit of the present invention. Accordingly, it is expressly
intended that all such variations, changes and equivalents which
fall within the spirit and scope of the present invention as defined
in the claims, be embraced thereby. |