Title: Proportional solenoid valve
Abstract: In a proportional solenoid valve, a valve drive portion that includes a coil, a core that is excited by application of a current to the coil, a plunger that is displaced by a magnetic attraction force generated by the excited core, and a spring that biases the plunger in a direction in which a distance to the core is increased. The spring is set so that a space is maintained between the plunger and an attraction surface of the core when the spring is fully compressed.
Patent Number: 6,938,875 Issued on 09/06/2005 to Ichinose, et al.
| Inventors:
|
Ichinose; Yuta (Tokyo, JP);
Onishi; Yoshihiko (Tokyo, JP);
Nakao; Kenji (Tokyo, JP)
|
| Assignee:
|
Mitsubishi Denki Kabushiki Kaisha (Tokyo, JP)
|
| Appl. No.:
|
682938 |
| Filed:
|
October 14, 2003 |
Foreign Application Priority Data
| Apr 25, 2003[JP] | 2003-121563 |
| Current U.S. Class: |
251/129.08; 251/129.18; 251/285 |
| Intern'l Class: |
F16K 031/02 |
| Field of Search: |
251/12918,129.08,129.15,284,285,363
|
References Cited [Referenced By]
U.S. Patent Documents
| 3469590 | Sep., 1969 | Barker.
| |
| 4346847 | Aug., 1982 | Rissi.
| |
| 5011043 | Apr., 1991 | Whigham et al.
| |
| 5246199 | Sep., 1993 | Numoto et al.
| |
| 5467961 | Nov., 1995 | Sausner et al.
| |
| 5503366 | Apr., 1996 | Zabeck et al.
| |
| 5513673 | May., 1996 | Slavin et al.
| |
| 5984263 | Nov., 1999 | Hosoya.
| |
| 6050542 | Apr., 2000 | Johnson et al.
| |
| 6336621 | Jan., 2002 | Ii et al.
| |
| 6422259 | Jul., 2002 | Moreno.
| |
| 6530528 | Mar., 2003 | Breyer et al.
| |
| Foreign Patent Documents |
| 44 23 103 | Jan., 1996 | DE.
| |
| 196 50 445 | Jun., 1998 | DE.
| |
| 198 47 304 | May., 2000 | DE.
| |
| 101 01 247 | Jul., 2001 | DE.
| |
| 1134470 | Sep., 2001 | EP.
| |
| 61-63088 | Apr., 1986 | JP.
| |
| 11-287349 | Oct., 1999 | JP.
| |
| 2002/-188744 | Jul., 2002 | JP.
| |
| 2002/-317726 | Oct., 2002 | JP.
| |
Primary Examiner: Bastianelli; John
Attorney, Agent or Firm: Sughrue Mion, PLLC
Claims
1. A proportional solenoid valve comprising:
a seat portion;
a valve element that is brought into and out of contact with the seat portion;
and
a valve drive portion that (i) includes a coil, a core that is excited by application
of a current to the coil, a plunger that is displaced by a magnetic attraction
force generated by the excited core, a rod that is abutted against the valve element
and is displaced integrally with the plunger, a bearing that holds the rod in a
slidable manner, and a spring that is provided between the bearing and the plunger
and biases the plunger in a direction in which a distance to the core is increased,
and (ii) displaces the valve element in accordance with the current applied to
the coil,
wherein the bearing is provided with an extension portion that extends along
an axial direction of the rod and regulates the displacement of the plunger toward
a core side, so that when the plunger is abutted against an end surface of the
extension portion, a space is maintained between the plunger and an attraction
surface of the core.
2. A proportional solenoid valve comprising:
a seat portion;
a valve element that is brought into and out of contact with the seat portion;
and
a valve drive portion that (i) includes a coil, a core that is excited by application
of a current to the coil, a plunger that is displaced by a magnetic attraction
force generated by the excited core, a rod that is abutted against the valve element
and is displaced integrally with the plunger, a spring that biases the plunger
in a direction in which a distance to the core is increased, and a load adjustment
member that is displaced with reference to the core in an axial direction of the
rod to thereby adjust a compressive load of the spring, and (ii) displaces the
valve element in accordance with the current applied to the coil,
wherein the load adjustment member is provided with an abutment portion which
an end surface of the rod is abutted against and regulates the displacement of
the plunger toward a core side, so that when the end surface of the rod is abutted
against the abutment portion, a space is maintained between the plunger and an
attraction surface of the core.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a proportional solenoid valve that displaces
a valve element by applying a current to a solenoid coil and obtains an output
pressure proportional to the value of the applied current, and a control method
for the proportional solenoid valve.
2. Description of the Related Art
In a conventional proportional solenoid valve, when a high current exceeding
an
ordinary working current range is applied to a solenoid coil or when a high pressure
is temporarily exerted on a valve element due to pulsation of an input pressure,
for instance, a plunger is displaced to exceed an ordinary operating range. In
this case, if an end surface of the plunger is attracted so as to directly contact
an end surface of a core, there occurs a malfunction of the plunger and output
pressure becomes unstable. In view of this problem, a stopper made of a non-magnetic
material is arranged between the end surface of the plunger and the end surface
of the core (see Japanese Utility Model Application Laid-Open No. 61-63088, for instance).
In the conventional proportional solenoid valve described above, however, the
stopper is arranged between the plunger and the core, so that the number of components
and the number of assembly steps are increased, which leads to an increase in cost.
In addition, there is a problem that variations occur in magnetic attraction force characteristics.
SUMMARY OF THE INVENTION
The present invention has been made in order to solve the problems described
above, and provides a proportional solenoid valve with which it is possible to
reduce the number of components and to stabilize magnetic attraction force characteristics.
In a proportional solenoid valve according to the present invention, a spring
is set so that a space is maintained between the plunger and an attraction surface
of a core when the spring is fully compressed. With this construction, the spring
is fully compressed before the plunger is abutted against the attraction surface.
The plunger does not directly contact an attraction surface.
Further, in a proportional solenoid valve according to the present invention:
a bearing is provided with an extension portion that extends along an axial direction
of the rod and regulates the displacement of a plunger toward a core side, and
when the plunger is abutted against an end surface of the extension portion, a
space is maintained between the plunger and an attraction surface of the core.
With this construction, even when the plunger is displaced to exceed an ordinary
operating range. The plunger does not directly contact an attraction surface.
Furthermore, in a proportional solenoid valve according to the present
invention, a load adjust member is provided with an abutment portion which an end
surface of the rod is abutted against and regulates the displacement of the plunger
toward a core side, and when the end surface of the rod is abutted against the
abutment portion, a space is maintained between the plunger and an attraction surface
of the core. With this construction, even when the plunger is displaced to exceed
an ordinary operating range. The plunger does not directly contact an attraction surface.
BRIEF DESCRIPTION OF THE DRAWINGS
Preferred embodiments of the present invention will be described in detail
based on the following figures, wherein:
FIG. 1 is a cross-sectional view of a proportional solenoid valve according
to a first embodiment of the present invention;
FIG. 2 is a magnified cross-sectional view of portion 11 shown in FIG. 1;
FIG. 3 is a cross-sectional view of a proportional solenoid valve according
to a second embodiment of the present invention;
FIG. 4 is a magnified cross-sectional view of portion IV shown in FIG. 3;
FIG. 5 is a cross-sectional view of a proportional solenoid valve according
to a third embodiment of the present invention; and
FIG. 6 is a magnified cross-sectional view of portion VI shown in FIG. 5;
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Embodiments of the present invention will now be described based on the
accompanying drawings.
First Embodiment
A proportional solenoid valve according to a first embodiment of the present
invention
is a hydraulic circuit for an electronically controlled automatic transmission
for an automobile (hereinafter simply referred to as an "automatic transmission"),
and is used to change the operating oil pressure in an operating portion of the
automatic transmission.
FIG. 1 is a cross-sectional view of the proportional solenoid valve according
to the first embodiment of the present invention. Note that in this drawing, there
is illustrated a proportional solenoid valve of a normally high type. Also, a coil
1 is accommodated in a cylindrical case
2 made of metal and a terminal
3 for connecting the coil
1 to a power supply is arranged outside
of the case
2. Further, the coil
1 and the terminal
3 are
molded by a resin portion
4 and a plunger accommodating hole
4a
that passes through the hollow portion of the coil
1 while extending
in the axial direction of the coil
1 is provided in the resin portion
4.
To one end portion of the resin portion
4, there is coupled a core
5
made of metal. This core
5 includes a cylinder portion
5a inserted
into one end portion of the plunger accommodating hole
4a and a flange
portion
5b that is abutted against an end surface of the resin portion
4. The flange portion
5b is welded to the case
2 at
the outer periphery of its joining surface with the case
2.
Into the cylinder portion
5a, there is inserted a first plain
bearing
6. Also, a cylindrical load adjustment member (spring pin)
7
is press-fitted into the cylinder portion
5a.
To the other end portion of the resin portion
4, there is coupled a guide
member
8 made of metal. This guide member
8 includes an annular-shaped
flange portion
8a abutted against an end surface of the resin portion
4, a cylindrical fitting portion
8b that protrudes from the
flange portion
8a, and a cylindrical valve guide portion
8c
that extends from one end portion of the fitting portion
8b.
The flange portion
8a is welded to the case
2 at the outer
periphery of its joining surface with the case
2. The diameter of the valve
guide portion
8c is made smaller than the diameter of the fitting
portion
8b.
In the valve guide portion
8c, there is fixed a second plain bearing
9. Into the first plain bearing
6 and the second plain bearing
9,
a rod
10 is inserted so as to be slidable. This rod
10 is arranged
inside of the core
5, the plunger accommodating hole
4a, and
the guide member
8 so as to be capable of reciprocating in the axial direction
of the coil
1.
To the middle portion of the rod
10, there is fixed a cylindrical plunger
11. That is, the rod
10 is press-fitted into the plunger
11.
A spring
12 is arranged between the plunger
11 and the first plain
bearing
6. The plunger
11 is made capable of reciprocating integrally
with the rod
10 inside of the plunger accommodating hole
4a.
In the cylinder portion
5a of the core
5, an attraction surface
5c is provided opposite to the end surface of the plunger
11.
In the valve guide portion
8c, there is inserted a ball-shaped
(spherical)
valve element
14 against which a tip portion of the rod
10 is abutted.
The load of the spring
12 that biases the plunger
11 toward the valve
element
14 is adjusted by changing the position of the load adjustment member
7. To the fitting portion
8b, there is fitted a housing
16
defining a flow path for oil. The housing
16 is welded to the flange portion
8a at the outer periphery of its joining surface with the flange
portion
8a.
Also, the housing
16 includes an input port
16a through
which the oil is supplied, an output port
16b that communicates with
the input port
16a, and a drain port
16c from which
a portion of the oil supplied through the input port
16a is discharged.
Further, between the input port
16a and the drain port
16c
and between the output port
16b and the drain port
16c,
there is provided a seat portion
16d which the valve element
14
is brought into and out of contact with.
Also, the case
2, the core
5, the guide member
8, and
the plunger
11 collectively constitute a magnetic circuit. The core
5
functions as a magnetic attraction portion for the plunger
11. A valve drive
portion
20 in this first embodiment includes the coil
1, the case
2, the terminal
3, the resin portion
4, the core
5,
the first plain bearing
6, the load adjustment member
7, the guide
member
8, the second plain bearing
9, the rod
10, the plunger
11, and the spring
12.
FIG. 2 is a magnified cross-sectional view of portion II shown in FIG.
1.
The spring
12 is set so that a space is maintained between the plunger
11
and the attraction surface
5c of the core
5 when the spring
12 is fully compressed. Note that FIGS. 1 and 2 each show a state where
the spring
12 is fully compressed, and an opening degree of the valve element
14 is changed within a range smaller than that shown in the drawings during
an ordinary operation.
Next, there will be described an operation in this embodiment. Under a state
where the coil
1 is not excited, the plunger
11 is pressed to the
valve element
14 side by the spring force of the spring
12. Consequently,
the valve element
14 is pressed against the seat portion
16d by
the rod
10, and the oil flow path to the drain port
16c is
closed. As a result, a high-pressure output is obtained from the output port
16b.
When the coil
1 is excited and an electromagnetic force attracting the
plunger
11 exceeds a predetermined degree, the plunger
11 and the
rod
10 are displaced in opposition to the spring force of the spring
12
in a direction in which their distances to the seat portion
16d are
increased. When doing so, a pressing force exerted through the rod
10 (force
obtained by subtracting the electromagnetic force generated in proportion to the
value of a current applied to the coil
1 from the compressive load of the
spring
12) and a fluid force resulting from a pressure output from the output
port
16b are exerted on the valve element
14, so that the
valve element
14 is displaced to a position at which there is struck a balance
between the pressing force and the fluid force. As a result, an output pressure
proportional to the current value is obtained from the output port
16b.
Note that in an ordinary working range, the plunger
11 does not contact
the attraction surface
5c of the core
5.
In the hydraulic circuit for an automatic transmission in which this proportional
solenoid valve is arranged, the oil accumulated in an oil pan, that is, an automatic
transmission fluid is pumped by an oil pump. The oil pump is driven in synchronization
with an engine. The automatic transmission fluid pumped by the oil pump is adjusted
to a predetermined pressure by a regulator or the like and then is sent to the
input port
16a under pressure.
Then, by the output pressure from the output port
16b, the opening/closing
of a control valve is controlled and a clutch is controlled, thereby performing
a shifting operation. Also, the automatic transmission fluid discharged from the
drain port
16c is recovered by the oil pan.
Here, when a high current exceeding an ordinary working current range is applied
to the coil
1 or when a high pressure is temporarily exerted on the valve
element
14 due to pulsation of an input pressure, for instance, the plunger
11 is displaced to exceed an ordinary operating range. However, the spring
12 is fully compressed before the plunger
11 is abutted against the
attraction surface
5c, so that a situation where the plunger
11
is attracted so as to directly contact the attraction surface
5c is
prevented. As a result, it becomes possible to obtain a stabilized output pressure.
Also, it is not required to provide an additional component between the plunger
11 and the attraction surface
5c, so that it becomes possible
to reduce the number of components and the number of assembly steps, contributing
to cost reduction. Further, it becomes possible to stabilize magnetic attraction
force characteristics.
Second Embodiment
Next, there will be described a second embodiment of the present invention.
FIG. 3 is a cross-sectional view of a proportional solenoid valve according to
the second embodiment, while FIG. 4 is a magnified cross-sectional view of portion
IV shown in FIG.
3. In these drawings, the first plain bearing
6
serving as a bearing is provided with a cylindrical extension portion
6a
that extends along the axial direction of the rod
10 and regulates the
displacement of the plunger
11 toward the core
5 side. With this
extension portion
6a, when the plunger
11 is abutted against
an end surface of the extension portion
6a, a space is maintained
between the plunger
11 and the attraction surface
5c of the
core
5. Here, the first plain bearing
6 is made of a non-magnetic
material. Also, the inside diameter of the extension portion
6a is
made larger than the inside diameter of the main body portion of the first plain
bearing
6. Further, even when the plunger
11 is abutted against the
end surface of the extension portion
6a, the spring
12 is
not fully compressed. Other constructions are the same as those in the first embodiment.
As described above, the first plain bearing
6 is provided with the extension
portion
6a, so that even if the plunger
11 is displaced to
exceed the ordinary operating range, a situation where the plunger
11 is
attracted so as to directly contact the attraction surface
5c is
prevented. As a result, it becomes possible to obtain a stabilized output pressure.
Also, it is not required to provide an additional component between the plunger
11 and the attraction surface
5c, so that it becomes possible
to reduce the number of components and the number of assembly steps, contributing
to cost reduction. Further, it becomes possible to stabilize magnetic attraction
force characteristics.
It should be noted here that in the second embodiment, there has been described
a case where one cylindrical extension portion
6a is provided, although
multiple rod-shaped extension portions may be provided at regular intervals in
the circumferential direction of the first plain bearing
6.
Also, in FIG. 4, the extension portion
6a is arranged inside
of the spring
12, although this portion
6a may also be arranged
outside of the spring
12.
Third Embodiment
Next, there will be described a third embodiment of the present invention.
FIG. 5 is a cross-sectional view of a proportional solenoid valve according to
the third embodiment of the present invention. FIG. 6 is a magnified cross-sectional
view showing a portion VI of FIG.
5. In these drawings, the load adjustment
member
7 is provided with the abutment portion
7a that regulates
the displacement of the plunger
11 toward the core
5 side by the
abutment with the end surface of the rod
10. When the abutment portion
7a
abuts the end surface of the rod
10, a space is maintained between the
plunger
11 and an attraction surface of the core
05. Also when the
abutment portion
7a abuts the rod
10, the spring
12
is not completely compressed. Other constructions are the same as those in the
first embodiment.
As described above, the load adjustment member
7 is provided with the
abutment
portion
7a, so that even if the plunger
11 is displaced to
exceed an ordinary operating range, a situation is prevented where the plunger
11 is attracted so as to directly contact the attraction surface
5c.
As a result, it becomes possible to obtain a stabilized output pressure. Also,
it is not required to provide an additional component between the plunger
11
and the attraction surface
5c, so that it becomes possible to reduce
the number of components and the number of assembly steps, contributing to cost
reduction. Further, it becomes possible to stabilize magnetic attraction force characteristics.
It should be noted here that in the third embodiment, although the abutment portion
7a is provided so that one end portion of the cylindrical load adjustment
member
7 is completely closed, as long as displacement of the rod
10
can be regulated it only a step portion need be provided on the inner surface of
the load adjustment member
7.
Also, in the first to third embodiments, there has been described a proportional
solenoid valve of a normally high type whose output pressure is high at the time
of non-energization and is decreased in accordance with an increase in applied
current. However, the present invention is also applicable to a proportional solenoid
valve of a normally low type whose output pressure is low at the time of non-energization
and is increased in accordance with an increase in applied current.
Further, although in the first to third embodiments a proportional solenoid
valve arranged in the hydraulic circuit for an automatic transmission has been
described, the present invention can be applied to a proportional solenoid valve
for any intended use.
*
