JPH0613361Y2 - 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, Japanese Patent Laid-Open No. 63-231
The one described in Japanese Patent No. 003 is known.

This is one in which push rods provided on solenoids are positioned at both ends of the spool, and the solenoids are excited to push the spools by the push rods to switch the spools, and pin holes are formed at both ends of the spool. The center line of the spool is aligned with the axial center line of the spool, one end of the spool is opened 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.

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, such an electromagnetic proportional pressure control valve is required to be downsized for reasons such as mounting on a vehicle, and for this reason, a small suction force of the solenoid is sufficient. like,
It is preferable to make the reaction force pin as small as possible.

However, in the conventional one, since the pin hole into which the reaction force pin is inserted is integrally formed on the spool by machining, there is a limit to reducing the diameter of the reaction force pin, and eventually the control pin is controlled. It was difficult to miniaturize the valve itself.

That is, since the reaction force pin is required to freely slide in the pin hole, it is required that the pin hole has a high processing accuracy, but the reaming processing that can reduce the diameter has sufficient accuracy. This is because it cannot be secured, and a clearance groove is required in the polishing process, and there is a limit to reducing the diameter due to restrictions on the tool.

An object of the present invention is to solve the above-mentioned conventional problems, to provide a reaction force pin (piston) with a small diameter, and to provide an electromagnetic proportional pressure control valve that can be downsized as a whole.

[Means for Solving the Problems] In order to achieve the above object, the present invention is a hole formed in the axial direction of both ends of a spool, one end of which is opened to the end of the spool and the other end of which is connected to an actuator port. , A reaction force piston is slidably inserted into the reaction force piston, a push rod driven by a solenoid is positioned at both ends of the spool while being in contact with the reaction force piston, and the spool is pushed by the push rod by exciting the solenoid. In an electromagnetic proportional pressure control valve adapted to switch the spool by pressing, the sleeve is mounted in the hole, and the reaction force piston is slidably inserted in the sleeve.

[Operation] According to the present invention, separate sleeves are attached to the holes formed at both ends of the spool, and the reaction force piston is slidably inserted into the sleeves.

Therefore, the diameter of the piston hole of the sleeve can be reduced without restriction in processing, and the surface roughness of the hole can be easily set to a value suitable for sliding.

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

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

A spool 14 is slidably installed in the spool hole 11, and both end surfaces of the spool 14 are formed in the spring chamber.
12,13. Then, the spring chamber 12,
13 includes a lid member 15 having solenoids 17 and 18 incorporated therein.
And one end of 16 is screwed and it is plugged.

Stepped through holes 19 and 20 are formed in the lid members 15 and 16 on the axial center lines thereof.

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 push rods 21 and 22 have movable iron cores 2
5, 26 are press-fitted, and the pressing force of the push rods 21, 22 is controlled in proportion to the exciting current of the solenoids 17, 18.

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

In addition, the stepped holes 3
3, 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.

Cylindrical sleeves 39, 40 are press-fitted and fixed in the stepped holes 33, 34, and the relief grooves 39A, 40A are previously fitted in the sleeves 39, 40.
Is formed, and after the piston 14 is mounted on the spool 14, the inner diameter portion is ground to form piston sliding holes 39B, 40B.

The reaction force pistons 41, 42 are slidably inserted into the piston sliding holes 39B, 40B as described above, and the reaction force pistons 41, 42 and the outer ends of the sleeves 39, 40 are included in the spool 14. The outer ends are in contact with the push rods 21, 22 via the cap members 43, 44.

It should be noted that the other embodiment shown in FIG.
The processing method of 9,40 is different, and after processing to a basic diameter by boring or reaming in advance, ball varnishing is applied as finishing processing, and it is press-fitted and fixed to the spool 14. According to this embodiment, the processing cost can be remarkably reduced.

The lands 37 and 38 are actuator ports formed on the valve body 10 when the spool 14 is in the neutral position.
It maintains the state of underlap for 43 and 44.

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 of the solenoids 17 is excited, the push rod 21 pushes the spool 14 via the cap member 43 and moves the spool 14 against the centering spring 32. 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 51 of the cylinder S.
And the hydraulic oil in the left side chamber 50 is returned to the tank T. 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 excitation radio wave to the solenoids 17 and 18.

When the spool 14 is switched as described above, the cylinder S operates, but the load pressure of the cylinder S at this time is the stepped hole.
It is guided to 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 push rod 22 to bend the spring 22A at the outer end of the push rod 22.

In this way, pressure acts on the reaction force piston 42,
When the push rod 22 is pressed by the spring 22A,
The force acting on the reaction force piston 42 acts on the spool 14 as a reaction force against the moving direction thereof.

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 is operated by the solenoid 17
Will be moved to a position where the pressing force of the push rod 21 determined by the exciting current 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 such that one solenoid 17 is excited. 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 a spool
It takes into account that the volume changes with the movement of 14.

Any material can be selected as the material of the sleeves 39 and 40. For example, cast iron is more preferable because the slidability with the reaction force pistons 41 and 42 is improved.

[Advantage of Invention] According to the present invention, the reaction force piston is slid in the sleeve which is separate from the spool, so that the piston sliding hole can be made small in diameter without restriction in processing. As a result, the solenoid can be downsized, and hence the entire control valve can be downsized.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, and FIG. 2 is a partial sectional view showing another embodiment of the present invention. 10 ... Bubble body, 14 ... Spool, 17,18 ... Solenoid, 21,22 ... Push rod, 33, 34 ... Stepped hole, 39, 40 ... Sleeve, 41, 42 ... Reaction piston, 43, 44 ... Actuator port .

Claims (1)

[Scope of utility model registration request] 1. A reaction force piston is slidably inserted into a hole formed in the axial direction of both ends of the spool, one end of which is opened to the spool end, and the other end of which is communicated with an actuator port. An electromagnetic proportional pressure control valve in which a push rod driven by a solenoid is positioned at both ends of the spool while abutting against a piston, and the spool is switched by pushing the spool by exciting the solenoid. In the electromagnetic proportional pressure control valve, the sleeve is mounted in the hole, and a reaction force piston is slidably inserted into the sleeve.