JPH082543Y2 - Solenoid proportional pressure control valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is used in an electromagnetic proportional pressure control valve, particularly in a four-wheel steering system, etc., and is adapted to control the pressure by switching spools in proportion to the exciting current of a solenoid. The present invention relates to an electromagnetic proportional pressure control valve.

[Prior Art] Conventionally, as a solenoid valve of this type, for example, JP-A-63-2
The one described in Japanese Patent No. 31003 is known.

This is one in which push rods provided on a solenoid are positioned at both ends of a spool, and by exciting the solenoid, the push rod pushes the spool to switch the spool, and pin holes are formed at both ends of the spool. Align its center line with the axial center line of the spool, open one end to the spool end, and
The other end is connected to the actuator port. Moreover, while the reaction force pin is slidably inserted into this pin hole and the push rod is brought into contact with this reaction force pin,
A stopper is provided outside the push rod, and a clearance equal to or larger than the effective stroke of the spool is provided between the stopper and the outer end of the push rod.

Further, centering springs are arranged at both ends of the spool via spring retainers, through which large-diameter portions formed at the outer ends of the reaction pins penetrate, to hold the spool in the neutral position.

Then, the relative difference between the pushing force of the push rod due to the exciting current of the solenoid and the switching reaction force of the spool acting on the reaction force pin is changed according to the pressure on the actuator port side, and the spool is changed according to the relative difference. Is controlled so that constant control can always be performed regardless of the flow rate of the actuator consumed or the change in oil temperature.

[Problems to be Solved by the Invention] However, in such an electromagnetic proportional pressure control valve, a spring retainer supporting one end of a centering spring for maintaining the neutral position of the spool is formed at the outer end of the reaction force pin. Since it is configured to penetrate the large diameter portion and slide with it, when relative displacement occurs with the spring retainer due to movement of the spool,
Sliding friction force is generated.

As a result, hysteresis is generated in the basic current-pressure characteristic of the electromagnetic proportional pressure control valve that attempts to obtain a predetermined proportional pressure by controlling the movement amount of the spool in accordance with the solenoid current, making accurate pressure control difficult. There was a problem of becoming.

An object of the present invention is to solve the above-mentioned conventional problems and to provide an electromagnetic proportional pressure control valve capable of arranging a spring retainer on a spool without generating sliding frictional force and capable of accurate pressure control. Especially.

[Means for Solving the Problem] A reaction force piston is provided in a hole that is formed in the axial direction of both ends of a spool housed in a valve body and has one end opened to the spool end and the other end communicated with an actuator port. It is slidably inserted, and while pushing against this reaction force piston, push rods driven by solenoids are located at both ends of the spool, and centering springs are arranged at both ends of the spools via spring retainers to excite the solenoid. In the electromagnetic proportional pressure control valve that pushes the spool with the push rod to switch the spool, a small diameter portion is formed at both ends of the spool, and the spring retainer is loosely fitted to the small diameter portion, and The taper part for restricting displacement in the direction orthogonal to the spool axis is And an inner diameter portion of the spring retainer, and at least one of an outer diameter portion of the valve body and the spring retainer.

[Operation] According to the present invention, the spring retainer is loosely fitted to the small diameter portion formed at both ends of the spool, and the taper portion is at least one of the small diameter portion and the retainer inner diameter portion, and the valve body and the spring retainer outer diameter portion. It is provided in.

Therefore, when the spool moves in the direction of compressing one of the centering springs, the spool and the spring retainer move integrally. When moving in the opposite direction, the spool moves without contacting the inner diameter of the spring retainer that is loosely fitted. Therefore, the occurrence of hysteresis is prevented without the generation of sliding frictional force. Even if the spring retainer is displaced in the direction orthogonal to the spool axis due to vibration, etc., this is regulated by the taper part, and the spool and the inner diameter part of the spring retainer are completely in contact with each other. Is blocked.

[Embodiment] An embodiment of the present invention will be described below with reference to the accompanying drawings.

1 and 2 show an embodiment of the present invention. First
In the valve body 10 of the embodiment of the present invention shown in the figure, a spool hole 11 is formed along the axial center line thereof, and
Spring chambers 12 and 13 are formed at both ends of the spool hole 11.

A spool 14 is slidably installed in the spool hole 11, and a small diameter portion 14 formed at both ends of the spool 14
A and 14A project into the spring chambers 12 and 13, respectively. Then, in the spring chambers 12 and 13, solenoids 17 and 1
One ends of lid members 15 and 16 each containing 8 are screwed together to cover it.

The lid members 15 and 16 are provided with stepped through holes 19 and 20 on the axial center line.
Are formed.

The push rods 21 and 22 are passed through the through holes 19 and 20, the inner ends of the push rods 21 and 22 are exposed to the spring chambers 12 and 13, and the outer ends are covered with springs 21A and 22A. It faces the stoppers 23 and 24 screwed to the screws 15 and 16. The movable iron cores 25, 26 are press-fitted into the push rods 21, 22, and the pressing force of the push rods 21, 22 is controlled in proportion to the exciting current of the solenoids 17, 18.

Then, spring retainers 29, 30 are provided on the spool side in the spring chambers 12, 13 and centering springs 31, 32 are interposed between the spring retainers 29, 30 and the lid members 15, 16.

In addition, the spring retainers 29, 30 include (second
One of them is enlarged and shown in the drawing), and tapered portions 29A and 30A are formed at the ends of the inner diameter portion. On the other hand, tapered portions 14B, 14B having a shape corresponding to the above-described tapers 29A, 30A are formed at the base end portions of the small diameter portions 14A, 14A of the spool 14. The spring retainers 29 and 30 are the small diameter portion 14 of the spool 14.
It is loosely fitted in A and 14A and abuts on the large diameter end faces 14C and 14C of the spool 14.

In addition, stepped holes are provided on the shaft centerlines at both ends of the spool 14.
33, 34 are formed, the outer ends of the stepped holes 33, 34 are opened to the spring chambers 12, 13 side, and the other end is connected through the communication holes 35, 36 orthogonal to the axis of the spool 14 to the spool. It communicates with the outer peripheral portion of 14 lands 37, 38.

Reaction force pistons 41, 42 are slidably inserted in the stepped holes 33, 34, and the reaction force pistons 41, 42 are included in the spool 1
The outer end of 4 is a push rod via the cap members 41A and 42A.
It is in contact with 21,22.

The lands 37 and 38 maintain an underlap state with respect to the actuator ports 43 and 44 formed in the valve body 10 when the spool 14 is in the neutral position.

When the spool 14 is in the neutral position shown in the figure, the pump port 45 communicates with the tank ports 46 and 47, so that the oil discharged from the pump P leaks into the tank T.

Now, when one solenoid 17 is excited, the push rod 21 pushes the spool 14 via the cap member 41A,
The spool 14 is moved integrally with the spring retainer 30 while being compressed against the centering spring 32.

At this time, since the spring retainer 29 on the left side in the drawing is loosely fitted to the small diameter portion 14A of the spool 14, the spool 14 is allowed to move without generating any sliding frictional force. Even if the spring retainer 29 is displaced in the direction orthogonal to the axis of the spool 14 due to vibration or the like,
The displacement is restricted by the contact between the tapered portions 29A and 14B,
Entire contact between the inner diameter of the spring retainer 29 and the spool 14 is prevented.

When the spool 14 moves in this way, the actuator port 43 and the tank port 46 communicate with each other, and the pump port 45 and the actuator port 44 communicate with each other.

Therefore, the oil discharged from the pump P is the right chamber of the cylinder S.
51 while the hydraulic oil in the left chamber 50 is supplied to the tank T.
Is returned to. However, depending on the amount of movement of the spool 14, the above-mentioned underlap portion is not sufficiently blocked, so that part of the oil discharged from the pump P flows out from the tank port 47 and is returned to the tank. That is, the movement amount of the spool 14,
In other words, the supply flow rate to the cylinder S is controlled according to the exciting current to the solenoids 17 and 18.

If the spool 14 is switched as described above, the cylinder S
However, the load pressure of the cylinder S at this time is guided to the stepped hole 34 and acts on the reaction force piston 42.

When the load pressure acts on the reaction force piston 42 as described above,
First, the reaction force piston 42 moves together with the cap member 42A and the push rod 22, and the push rod 22
The spring 22A at the outer end is bent so that the cap member 42A contacts the end surface of the lid member 16.

When the pressure acts on the reaction force piston 42 and the cap member 42A contacts the end surface of the lid member 16 in this manner, the force acting on the reaction force piston 42 acts on the spool 14 in the moving direction. Acts as a reaction force against.

As described above, the reaction force corresponding to the load pressure of the cylinder S acts on the spool 14, so that the spool 14
It moves to a position where the pressing force of the push rod 21 determined by the exciting current of 17 and the reaction force determined by the load pressure of the cylinder S are balanced.

When the other solenoid 18 is excited, the spool 14 moves to the left in the drawing to supply pressure oil to the left chamber 50 of the cylinder S. The control mode is that one solenoid 17 is excited. The description is omitted because it is similar to the above case.

Further, reference numerals 52 and 54 in the drawing are oil passage holes formed in the valve body 10, and connect the spring chambers 12 and 13 and the movable core chamber to the tank port 47. This is because the volume changes as the spool 14 moves.

Next, another embodiment of the present invention is shown in FIG. In this embodiment, the spool 14 and the spring retainers 29, 30 are the same as the previous embodiment.
Whereas the taper portion is provided in and, the taper portion is provided in the balg body 10 and the spring retainers 29, 30.
Spring retainer 29,30 when moving spool 14
The sliding contact between the spool and the spool 14 is completely cut off.

That is, in this embodiment, the spring retainer 2
Tapered portions 29B and 30B are formed at the ends of the outer diameter portions of 9,30, and tapered portions 10A and 10A corresponding to these are formed in the valve body 10.

With this configuration, when the spool 14 is moved, there is no contact with the spring retainers 29, 30 in the loosely fitted state, and even if the spring retainers 29, 30 are displaced in the direction orthogonal to the axis of the spool 14, the taper is reduced. It is regulated by a part, and sliding contact between the spool 14 and the spring retainers 29, 30 is prevented. However, it goes without saying that it is necessary to make the separation distance of the tapered portion smaller than the loose fitting margin.

[Advantage of the Invention] According to the present invention, the spring retainers are loosely fitted to the small diameter portions at both ends of the spool, and the taper portions for restricting the displacement of the spring retainers in the direction orthogonal to the spool axis are provided. It is possible to prevent generation of dynamic frictional force, and it is possible to perform accurate pressure control without hysteresis due to current-pressure characteristics.

[Brief description of drawings]

1 is a sectional view showing an embodiment of the present invention, FIG. 2 is an enlarged sectional view showing a part thereof, and FIG. 3 is a partially enlarged sectional view showing another embodiment of the present invention. 10 …… Valve body, 10A …… Tapered part, 14 …… Spool, 14A …… Small diameter part, 14B …… Tapered part, 17,18 …… Solenoid, 21,22 …… Push rod, 29,30 …… Spring Retainer, 29A, 30A, 29B, 30B …… Tapered part, 33,34 ……
Stepped hole, 41, 42 …… Reaction force piston, 43, 44 …… Actuator port.

Claims (1)

[Scope of utility model registration request] 1. A reaction force piston is slidable in a hole which is formed in the axial direction of both ends of a spool housed in a valve body and has one end opened to the spool end and the other end communicated with an actuator port. Inserting, arranging push rods driven by solenoids at both ends of the spool while making contact with the reaction force piston, and disposing centering springs at both ends of the spools via spring retainers to excite the solenoids. In the electromagnetic proportional pressure control valve configured to push the spool with the push rod to switch the spool, a small diameter portion is formed at both ends of the spool, and the spring retainer is loosely fitted to the small diameter portion, and The taper part for restricting the displacement of the spring retainer in the direction orthogonal to the spool axis is The small diameter portion and the spring retainer inner diameter portion, and the electromagnetic proportional pressure control valve, wherein the valve body and the spring retainer outer diameter, which is provided on at least one of.