JPS63199985A - Hydraulic control valve with self-cancel mechanism - Google Patents

Abstract

PURPOSE:To simplify the structure of these parts as well as to miniaturize them, by installing an extension shaft in a spool, setting up a spool neutral position resetting mechanism and a detent mechanism on an outer surface of this extension shaft, and installing a detent release mechanism in an upper part of the extension shaft. CONSTITUTION:An extension shaft 3 is extendedly installed in a spool 2 to be projected out of a valve housing 1. A spool neutral position resetting mechanism 6 consisting of a spring 6 and spring bearings 21 and 22 and a detent mechanism 7 consisting of ring projections 14a and 14b, a ball 29. A ball presser 30 or the like are installed on a outer circumference of this extension shaft 3. In addition, a detent release mechanism, interconnecting an interval between a cylinder chamber 46 at the left of a flange 34 of the ball presser 30 and a high pressure flow passage P'', is installed in the position displaced in a height direction of the extension shaft. With this constitution, a structure is simple, manufacture and assembly are easy and, what is more, the cross direction sizes of the spool neutral position resetting mechanism, the detent mechanism or the like become equal to the valve housing 1 or less than it.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a hydraulic control valve, and particularly to a hydraulic control valve with a self-cancelling mechanism.

[Conventional technology and its problems]

Spool-type control valves are commonly used as means for controlling the operation of various hydraulic actuators in construction machinery, agricultural machinery, and the like. In this control valve, in addition to a device that returns the spool to the neutral position, a detent device that positions the spool to the operating position is provided, and furthermore, when the circuit pressure of the hydraulic oil circuit rises above a certain level, the restraining operation of the detent device is released. Providing a self-cancelling mechanism is known from Japanese Utility Model Application Laid-Open No. 60-24978.

However, in conventional control valves, a detent release mechanism is built into the spool, that is, a deep cylindrical hole and a pilot oil passage for operating the release mechanism are connected from the protruding end of the spool, and the boundary between the cylindrical hole and the pilot oil passage is A valve seat is fixed to the cylindrical hole, and a release piston, a release valve body, a spring, and its support body are arranged in the cylindrical hole, and a bushing rod that connects to the support body is inserted through the center of the release piston. It was received by an adjustment screw screwed into a sleeve whose rear end was fixed to the end of the cylindrical hole.

As a result, the configuration is complicated, there are many parts, and it is necessary to form a screw deep inside the cylindrical hole and install a valve seat and a release valve body, making it difficult to manufacture and assemble the spool. was there.

Furthermore, in order to incorporate the self-cancellation mechanism into the spool as described above, the spool becomes thicker than necessary, and the balls that make up the detent device are arranged in holes formed in the spool itself, and locking protrusions are provided on the outer circumference of the spool. A sleeve having a diameter was provided to allow the ball to be engaged and disengaged.

Therefore, the outer diameter dimension, especially the width dimension, including the case of the tedent release device and the detent device becomes larger than the width of the valve housing. As a result, although the valve itself is standard, it becomes a special valve, and when stacked with other valves, a spacer is required, or the valve housing needs to be thickened, making it difficult to use. The problem was getting worse.

[Means for solving problems]

The present invention was developed through research to solve the above-mentioned problems.The purpose of the present invention is to provide a good detent function and an automatic release function, a simple structure, and a small number of parts. This type of hydraulic system with a self-cancelling mechanism is easy to assemble, has a small external dimension, especially in the width direction, and can be made smaller to be equal to or smaller than the valve housing, and can be easily stacked without causing oil leakage. The purpose of this invention is to provide a control valve.

To achieve this object, the present invention provides a spool protruding from a valve housing with an extension shaft that is concentric and solid with the spool, and uses the outer surface of the extension shaft as a component to provide a spool neutral return mechanism and a detent mechanism. , and at a position displaced in the height direction from the spool and the extension shaft,
A detent release mechanism is provided that includes a passage connecting a high-pressure flow path in the valve housing and an outer peripheral area of the ball pressing means of the detent mechanism.

〔Example〕

Embodiments of the present invention will be described below with reference to the accompanying drawings.

1 and 2 show an embodiment of a hydraulic control valve with a self-cancelling mechanism according to the present invention, and FIG. 3 shows its hydraulic circuit.

1 is a valve housing, into which a spool 2 is slidably inserted into a predetermined position. As is well known, this valve housing 1 includes cylinder ports A and B that communicate with the actuator, a parallel feeder (high pressure flow path) P' that communicates with the pump port P, a low pressure flow path T' that communicates with the tank port T, and a carrier. The parallel feeder P' is equipped with a neutral flow path N' leading to an overport N, and the parallel feeder P' is equipped with a load check valve Pa.
It communicates with an arcuate high-pressure flow path P'' which can communicate with cylinder ports A and B via the cylinder ports A and B.

The spool 2 has a narrow diameter portion 9 for selectively communicating the parallel feeder P' and the cylinder ports A and B.
, 10 and a narrow diameter portion 11.11 for communicating or blocking the neutral flow path N'.

Reference numeral 3 denotes an extension shaft, which is fixed to the end of the spool 2 protruding from the valve housing 1 with a screw or the like. This extension shaft 3 consists of a solid shaft concentric with the spool 2, and has a base portion 12 with a smaller diameter than the spool 2, a stopper portion 13 with a larger diameter than the base portion 12, and an annular projection 14 on the thin shaft portion in front of the extension shaft 3.
a, 14b and restraining portions 15a, 15b are formed.

4 is a front holder whose end face is in close contact with the end face of the valve housing 1; 5 is a rear holder connected to the end face of the front holder 4; the holder is fastened to the valve housing 1 by a bolt 17; The front holder 4 and the rear holder 5 are constructed in a block shape, and the front holder 4 has a neutral return chamber 18 and an opening 19 having a smaller diameter than the chamber 18 concentrically with the extension shaft 3.
are connected to each other, and a ring-shaped guide part 25 is further formed that projects rearward from the end face via a step part 26, and the rear holder 5 has a detent chamber that communicates with the opening 19 and has a larger diameter than the ring-shaped guide part 25. 20 is recessed, and the guide portion 25 is fitted into the inner periphery of the detent chamber 20.

Reference numeral 6 denotes a spool neutral return mechanism, which is provided within the neutral return chamber 18 with the extension shaft 3 as a component. That is, this mechanism consists of a pair of spring receivers 21 and 22 arranged in the neutral return chamber 18, and a return spring 23 interposed between the spring receivers 21 and 22. , the back part is supported by the seal ring fixing plate 16, and the front part is supported by the spool 2.
The spool 2 comes into contact with the end surface 24 of the spool 2, and moves in conjunction with the forward movement of the spool 2. Further, the spring receiver 22 has a back part supported by the end wall 180 of the neutral return chamber 18, and a front part abuts against the stopper part 13 of the extension shaft 3,
It is designed to move in conjunction with the spool 2 when it moves backward.

Reference numeral 7 denotes a detent mechanism, which is provided within the detent chamber 20 with the extension shaft 3 as a component. That is,
The mechanism includes a guide part 25 fitted along the inner wall from the mouth end of the detent chamber 20 as described above, and a cylindrical ball holder 2 inserted into the guide part 25 and positioned by a step part 26.
7, balls 29 and 29 loosely fitted into a plurality of holes formed in the cylindrical ball holder 27, and a cylindrical ball disposed on the outer periphery of the cylindrical ball holder 27 and movable in the axial direction of the detent chamber 20. A detent is arranged around the outer circumference of the cylindrical ball holder 27 and has one end supported by a support portion 32 formed on the ball holder 30 and the other end supported by an end wall 33 of the detent chamber 20. It is equipped with a spring 31 for use.

As shown in FIG. 1a, the ball presser 30 has a collar 34 projecting from its end, and a seal ring 35 is attached to a surface 340 of the collar 34 facing the detent interior wall 200. Further, the other end outer peripheral surface 341 is the guide portion 25
A seal ring 36 is also attached to the outer peripheral surface 341 of the other end.

A seal ring 37 is also attached to the outer circumferential surface of the guide portion 25 that is in contact with the detent interior wall 200, so that an oil-tight cylinder chamber 46 is formed between the ball presser 30, the detent interior wall 200, and the tip of the guide portion. It is supposed to be done.

Reference numeral 8 denotes a detent release mechanism that hydraulically automatically releases the detent mechanism 7. In the present invention, this mechanism is not installed inside the spool, but is installed in the spool neutral return mechanism 6.
and is separately installed at a position separated from the detent mechanism 7 in the height direction, and communicates with the detent mechanism 7 and the flow path in the housing through a passage when necessary.

That is, this detent release mechanism 8 includes a pilot passage 38 bored in the front holder 4 and a valve seat 39 fixed to the end of this passage 38.

A spring chamber 40 formed to penetrate from the rear end to the front end of the rear holder 5, a relief valve 41 inserted so as to be in contact with the valve seat 39 through the spring chamber 40, and a rear end of the spring chamber 40. A relief spring 43 is provided between the adjustment screw 42 attached to the relief valve 41 and the relief valve 41.

In the valve housing 1, one end communicates with the pilot passage 38, and the other end passes through a high pressure flow path, that is, in the vicinity of the cylinder port B in this embodiment, and an arcuate high pressure flow path P''.
Passages 44a and 44b communicating with the 1
A bushing 45 is fixed to the passage 44b so as to cross the flow path to the cylinder port B. This configuration is to avoid an increase in the wall thickness of the valve housing 1, and if there is an allowance in the wall thickness of the valve housing 1, the passage 44a.

44b may be formed to bypass cylinder port B.

The rear holder 5 also has a passage 4 that communicates the inside of the spring chamber 40 with the cylinder chamber 46 of the detent chamber 20.
7 is formed, and when the relief valve 41 is opened, the cylinder chamber 4
Hydraulic oil is led to 6.

On the other hand, a return passage 48 connecting the cylinder chamber 46 and the low-pressure passage in the valve housing 1 is bored at a position symmetrical to the passage 47, and this passage 48 has an orifice 4 for controlling the flow rate.
9 is provided. 50 is a blind plug.

The scope of application of the present invention is not limited to the 3-position, 4-way, spring center valve as shown in the drawings, but is applicable to various hydraulic control valves such as 4-position, 4-way valves.

[Effect of the embodiment]

Next, the operation of the above configuration will be explained.

FIG. 1 shows a state in which the spool 2 is held neutral by the return spring 23 of the spool neutral return mechanism 6.

In this state, cylinder ports A and B are closed, and the hydraulic oil discharged from the pump flows from the pump boat P to the carryover boat N through the neutral flow path N'.

When the spool 2 is pushed in in the direction of the arrow to operate the actuator, the neutral flow path N' is closed as shown in FIG. To communicate.

The hydraulic oil from the pump boat P pushes up the load check valve Pa and flows into the cylinder port A from the parallel feeder P'. On the other hand, the return oil from the cylinder port B is returned to the tank via the narrow diameter portion 10 from the low pressure passage T'.

When the spool 2 slides as described above, the extension shaft 3 also moves together, and in the neutral return chamber 18, the spring receiver 21 is pushed by the spool end face 24, thereby compressing the return spring 23. In addition, the detent chamber 20
, the annular protrusions 14a and 14b formed on the outer peripheral surface of the extension shaft 3 come into contact with the balls 29.29 held in the ball holder 27, and as the spool 2 and extension shaft 3 continue to move, the balls 29.29. 29 climbs the annular protrusion 14a while escaping in the radial direction so as to move the ball presser 30 in the axial direction, and the moment it climbs over this, the ball presser 30 returns and falls into the retaining part 15a, and the spool 2 is now Holds securely in working position.

The hydraulic oil that has flowed through the arc-shaped high-pressure flow path P11 flows into the passage 38 through the bush 45 from the through hole 44b.

When the inflow pressure is lower than the set pressure of the relief valve 41, the closed state of the relief valve 41 is maintained, so the detent release force does not act on the detent chamber 2o. When an external force is applied, the relief valve 41 opens, and the hydraulic oil flows from the spring chamber 40 through the passage 47 into the cylinder chamber 46 of the detent chamber 20, and the return passage 4 whose end communicates therewith.
8, and is returned to the low-pressure flow path T' while the flow rate is restricted by the orifice 49. When the amount of flow into the cylinder chamber 46 becomes greater than the amount passing through the orifice 49, the pressure in the cylinder chamber 46 increases, and the ball holder 3o resists the detent spring 31 due to the pressing force acting on the collar 34 of the ball holder 3o. and slide the detent chamber 20.

As a result, the pressure on the ball 29.29 that had fallen into the holding portion 15a of the extension shaft 3 is loosened, and the spool 2 and the extension shaft 3 retreat due to the elastic force of the instantaneous return spring 23, so that the ball 29.29 Annular projection 14
a, the spool 2 moves backward until the spring receiver 22 comes into contact with the stopper part 13 of the extension shaft 3, and returns to the neutral state shown in FIG. Now the passages 38, 44a, 44b
The relief valve 41 is closed due to the decrease in the internal pressure.

The setting pressure of the detent release mechanism 8 is set by changing the setting force of the relief spring 43 by tightening the adjustment screw 42, but in the present invention, the adjustment screw 42 is placed outside the rear holder 5. , can be easily carried out with one touch, and replacement of the relief spring 43 is also easy.

The above explanation is for the case where the spool 2 is pushed in, but the same operation occurs when the spool 2 is pulled out.

〔Effect of the invention〕

According to the present invention as described above, a solid extension shaft 3 concentric with the spool 2 protruding from the valve housing 1 is connected to the spool 2, and the extension shaft 3 is used as a part of the component to return the spool to neutral. A mechanism 6 and a detent mechanism 7 are provided in sequence, and a hydraulic release mechanism 8 of the detent mechanism is separately provided at a position displaced in the height direction, and a passage connects the high-pressure flow path of the valve housing 1 and the cylinder chamber of the detent mechanism. As a result, the spool structure itself becomes simpler than when a detent release mechanism is provided inside the spool, and a long thin bushing rod and complicatedly shaped pistons are not required. Therefore, the configuration is simple, the number of parts is small, and there is no need for complicated machining of the spool or installation of parts into deep holes, making assembly and manufacturing easier.

Furthermore, since the detent release mechanism is separated from the spool, the diameter of the spool can be made thinner, and instead of pressing the ball of the detent mechanism outward in the radial direction of the spool and restraining it, the extension shaft is thinner than the diameter of the spool. The spool neutral return mechanism,
The dimensions of the detent mechanism, the detent release mechanism, and the casing housing them, particularly the widthwise dimension W, can be made smaller and equal to or smaller than the valve housing 1.

Therefore, stacking can be easily performed without requiring a spacer, which allows the unit to be made smaller and
Excellent effects such as being able to avoid oil leaks between sections can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal side view showing an embodiment of the hydraulic control valve with a self-cancelling mechanism according to the present invention in a neutral state, FIG. 1a is a partially enlarged view of FIG. 1, and FIG. 2 is a plan view of the valve of the present invention. 3 is a circuit diagram of the valve of the present invention, and FIG. 4 is a longitudinal sectional side view showing the operating state of the valve of the present invention. 1...Valve housing, 2...Spool, 3...
- Extension shaft, 6... Spool neutral return mechanism, 7... Detent mechanism, 8... Detent release mechanism, 14a, 14
b... Annular projection, 30-E) Ll presser, 44a, 4
4b. 47...Aisle

Claims (1)

[Claims] A spool protruding from the valve housing is provided with an extension shaft that is concentric and solid with the spool, and a spool neutral return mechanism and a detent mechanism are arranged around the extension shaft using the outer surface of the extension shaft as a component, and the spool and the extension A hydraulic control valve with a self-cancellation mechanism, characterized in that a detent release mechanism is provided at a position displaced in the axial and height direction, including a passage connecting a high-pressure flow path in the valve housing and a cylinder chamber of the detent mechanism.