JPS5928763B2 - fluid valve - Google Patents

Description

[Detailed description of the invention] The present invention relates to improvements in fluid valves.

The fluid-driven motor is controlled by a fluid control system that uses a working fluid to drive the motor.

For example, the motor-driven blade of an elevating scraper must move up and down and be held in a fixed position during operation.

Therefore, working fluid must be selectively conveyed to the motor's forward, reverse, and neutral or non-operating positions.

Directional control spool valves are commonly used for this purpose.

The spool valve includes a housing having an internally grooved aperture, the groove being positioned within the housing to engage or straddle lands separating the grooves for axial movement of the spool. is connected to a source of high pressure fluid by, but isolated from, the source of high pressure fluid.

When operating a device such as an elevating scraper, a detent mechanism holds the spool in the desired position so that the operator's hands are freed from duties such as steering after the spool has been moved to the desired position by movement of the shift lever. It is desirable to retain it.

Many such detent mechanisms are known which retain the spool against self-motion, but which are easily movable by forces exerted by movement of the control lever by the operator.

The engine that drives a vehicle is commonly used as a fluid source to maintain the pressure of the working fluid.

Once the engine is stopped and the fluid pressure is gone, it is more difficult to start the engine when the fluid motor is moving forward or reverse because of the extra load on the engine.

An even more serious problem is that during engine starting, when the fluid motor is in the operating position, the starting speed of the engine may reach a point where engine damage is caused or a resonant frequency of the drive train components occurs, causing one of these components to The problem is that they decrease at such a rate that one or more of them often fail.

The prior art is exemplified by the following US and UK patents.

Patent Number Date Inventor U.S. 2nd;
No. 848,014 August 19, 1958 Tenth No. 3,438.39 April 15, 1969 Barnes
No. 3,511,276 May 12, 1970 Jietzsen No. 3,602,245 August 3, 1971
1st Mysel No. 3,618,984 November 9, 1971 Cook No. 39 stone 9-8-; 583 No. 1
October 17, 972 Niles British 1,311,8
No. 97-1 The present invention maintains the spool of the spool valve in a selected operating position while the pressure of the working fluid is sufficient, but when the pressure of the working fluid is insufficient, such as when the drive engine is stopped, the spool is closed. This consists of a directional control spool valve that solves the above problem by providing a mechanism that automatically locks the valve into the neutral position.

The valve of the present invention comprises a conventional valve housing having a fluid inlet and at least three fluid outlets, and which directs high pressure fluid from the inlet to drive a fluid-operated motor in a forward or reverse direction or in a neutral state. It has internal grooves and lands positioned to cooperate with grooves in the valve spool during axial movement of the spool to direct this high pressure fluid away from the motor.

A spool centering device is provided within the valve housing surrounding the valve spool, the centering device housing a sliding spring positioned to slide between two extreme positions for engaging the valve housing. Consists of a housing.

The spring housing includes a compression spring and engages the spool to move toward a position in which it engages the valve housing when the spool moves in one direction.

A detent mechanism is provided to prevent the spool collar from moving forward, backward, or in a neutral position due to the spring.

The detent mechanism includes means pressed into the receiving groove by a spring operating between a high spring force position and a low spring force position, in which the detent mechanism is pressed firmly into the receiving groove. so that it is locked against movement by the centering spring.

However, when the spring force is low as a result of loss of fluid pressure, this detent mechanism cannot keep the spool from moving under the force of the centering spring.

The centering spring is normally positioned and operative to urge the spool to a neutral position.

Referring to the drawings, the valve, generally designated 10, includes a detent mechanism, generally designated 11.

The valve includes a valve body or housing 12 having stepped holes 14, 15, 16.

This housing 12 supplies high pressure working fluid to the fluid operated motor 4.
Inlet holes 18 , 19 for communicating high pressure working fluid to outlet holes 20 , 21 for distribution to 5 and outlet holes 22 , 23 for returning high pressure working fluid to storage tank 42 .

It is equipped with 24.

A valve spool 25 is reciprocatably mounted within the bore 14 and includes an annular groove 32 that controls fluid communication between the inlet and outlet bores.
．． 33.34.

Lands 27, 28, 29, 30° 31 forming 35 are formed on the spool.

The spool has a rod 36 that projects beyond the housing 12 and attaches the spool to a manual activation lever, not shown.

The activation lever is suitable for use by an operator to move the valve spool to the forward, reverse, or neutral positions shown.

High pressure fluid is supplied to a pair of branch conduits 37.3 by a pump 40.
8 to the inlet holes 18 and 19.

When the spool is in the neutral position, high pressure fluid flows through the annular recess 33.
34 , through hole 14 and back through outlet hole 23 to fluid storage tank 42 .

A return conduit 41 connects the bore 23 to a fluid storage tank 42 .

When the valve spool moves to the forward position, the annular groove 35 allows high pressure fluid to flow from the inlet hole 19 through the conduit 43 to the fluid actuator 4.
5 is connected to the outlet hole 21.

The motor is adapted to move high pressure working fluid in a forward direction as it passes through conduit 43.

Typically, the fluid motor lifts the blade of the lifting blade scraper when the spool is in the advanced position.

Fluid discharged from the motor passes through the motor and enters hole 20 through conduit 46, which is connected via branch conduit 47 to conduit 41 and ultimately to hole 22, which is connected to storage tank 42.
are communicated with each other via an annular groove 32.

When the spool is in the forward position, the inlet hole 18 is connected to the land 28.
．． 29 so that fluid pressure cannot enter the housing through this inlet hole.

When the valve spool 29 is in the reverse position, fluid pressure in the inlet hole 18 communicates through the annular groove 32 to the outlet hole 20, thereby providing high pressure fluid to the motor 45 via the conduit 46.

At this time, the motor is driven in the opposite direction, for example to lower the blade of the lifting blade scraper.

The fluid discharged by the motor passes through conduit 43 to hole 21.
through the spool valve 10 and the passage 24 to the conduit 4.
1 returns to tank 42 via conduit 48 which connects to tank 42 .

In the reverse position, the fluid pressure in the inlet hole 19 is
is blocked by

The centering device of the present invention is indicated generally at 50.

This centering device is located within the bore 15 and surrounds a portion of the spool that is smaller in diameter than the portion of the spool within the bore 14.

The centering device includes a sliding spring receiving housing 52 that moves within the bore 15.

A snap ring 53 is provided to limit the distance that housing 52 can slide by engaging housing 52 with valve housing 12.

an inwardly extending flange 54 formed at one end of the sleeve;
is positioned to engage a second snap ring 55 which is disposed within a groove formed in a reduced diameter portion 51 formed in the spool 25.

The inside of the flange engages one end of a helical spring 56, the other end of which abuts an annular retaining ring 57, which retains both shoulder 58 of valve housing 12 and shoulder 59 of spool 25. are in conflict with each other.

Therefore, when the spool 25 moves to the reverse position, the annular retaining ring 57 moves to the right, compressing the spring 56, and when the spool moves to the forward position, it moves the spring housing 52 to the left. This causes the spring 56 to be compressed.

Thus, spring 56 urges the spool from either direction of travel to a neutral position.

The detent mechanism, indicated generally at 11, includes a number of balls 61 held in axial position by retainers 62.

Since the retainer 62 is firmly held between the pair of snap rings 64 and 65, it will not move in the axial direction relative to the hole in the valve housing 12.

Three grooves 66, 67, 68 are formed in the extension of the valve spool, these grooves being shaped to accommodate the balls 61, and the valve spool can be moved forward, reverse or neutral as appropriate, as described above. It is located on the extension of the valve spool to hold it in the correct position.

An annular cam ring or annular member 70 is slidably disposed within bore 15 and around valve spool extension 69.

Ring 70 has an inclined cam surface 71 in contact with ball 61 and near retainer 62 .

A compression spring 72 is positioned in the largest hole 16 and the ring 70
The hole 15 extends into the hole 15 so as to apply a pressing force to the hole 15 .

The opposite end of the spring 720 is held by a holder 74 positioned to slide in the axial direction within the hole 1G.

The retainer 74 has a flange 75 positioned to engage the spring 72 to maintain a snug fit within the bore 16 and also to act as a stop means.

An end cap 77 is attached to the bolt 7 so as to close the outer end of the hole 16.
8 is attached to the valve body 12.

The end cap is provided with a hole 80 in which a piston 81 is maintained which acts against the spring retainer 74.

A rod 82 of piston 81 fits into a hole 84 in retainer 74 to help align these movable members.

Preferably, this retainer is firmly secured to the rod 82 by a force fit.

An inlet passageway 87 is provided through the end cap 77, in the case shown a threaded plug 85.

Conduit 88 supplies pressurized fluid from pump 40 to inlet passage 87 so that this fluid acts on piston 81 to compress spring 72 when the fluid is under high pressure.

A conventional pressure relief valve 90 is incorporated in conduit 88 to avoid creating burst pressures in the fluid system by releasing high pressure fluid back to storage tank 42.

In operation, fluid pressure at inlet 87 is transmitted to piston 81 to move the piston against retainer 74 and compress spring 72.

Spring retainer 74 is restricted from movement from the illustrated position to a position where it abuts shoulder 76 of valve housing 12.

When abutting the shoulder 76, the spring 72 causes the annular ring 7 to
The force applied to groove 66 is sufficient to prevent ball 61 from moving spool 25 under the action of spring 56.
．． 67.68 is chosen to be locked.

However, a detent mechanism including ball 61 and one of grooves 66, 67, 68 prevents spool 25 from moving spool 25 against manual operation of a lever that changes the spool's position to either forward, reverse, or neutral positions. It is not held with sufficient force to lock the movement.

Manual operation of the shift lever applies sufficient force on spool 25 to compress spring 72 even further so that ball 61 moves into a sufficiently different groove.

When fluid pressure is removed from line 88 , spring 72 is fully extended and in this position it is sufficient to position and lock the spool against annular ring 70 and ball 61 against the force of spring 56 . Never give up your strength.

Preferably, spring 72 is fully relaxed when fully extended.

As previously stated, the centering spring 56 is compressed when the spool is in either the forward or reverse position.

When there is no fluid pressure in the fluid system, there is no fluid pressure in line 88, allowing spring 72 to extend against piston 81.

This spring therefore pushes the retainer 74 back into contact with the end cap 77 and the force exerted by the spring 72 is reduced to such a force that the spool 25 is no longer locked against the action of the compression spring 56. .

As a result, when the pressure in the fluid system is removed, the spring 56 will expand and this action will cause the spring 56 to position the spool in a neutral position so that high pressure fluid entering the valve via the holes 18 or 19 will not pass through the motor 45 but rather through the holes. Tank 4 after 23
Returned to 2.

This effect occurs whether the spool is in the forward or reverse position when fluid pressure is removed.

If the spool is in a neutral position when fluid pressure is removed, it will remain in that position.

Thus, the valve of the present invention is equipped with a fluid that holds the valve in a forward, reverse, or neutral position so as not to cause any movement other than that carefully performed by the operator when there is actuating fluid pressure in the system. Includes pressure-responsive anti-shock mechanism.

When the system loses fluid pressure, the spool valve can automatically return to a neutral position to avoid restart problems and problems associated with linkage resonant frequencies.

When the engine is restarted, the detent mechanism is reactivated to firmly hold the valve in the neutral position until careful movement by the operator moves the valve to the forward or reverse position.

It will be readily appreciated that a pressure responsive lock mechanism is a desirable safety mechanism in that it prevents the valve from being in the activated position when the engine is started.

If the motor controlled by the valve is in the starting position, it will cause an unexpected start when the engine is started, posing a great danger to those working on or around the vehicle.

Preferred embodiments of the present invention are summarized as follows.

(1) The detent means includes a plurality of annular grooves extending around the spool, a plurality of balls mounted in the valve body surrounding the spool so as to engage with the grooves, and cam means for engaging a ball and forcing said ball into said groove.

(2) The cam means includes an annular member that is reciprocably provided in the hole and has an inclined surface that engages with the ball, and a hydraulic mold stone that is provided in the valve body and is operatively connected to the ring. The valve according to paragraph 1 above, comprising:

(3) The valve of item 2, further comprising spring means connecting the piston to the annular cam member.

(4) The valve of paragraph 3, further comprising an annular shoulder disposed within the bore, the ball being trapped between the shoulder, the spool, and the annular cam member.

(5) The valve according to item 3, further comprising stopper means for restricting movement of the piston.

[Brief explanation of drawings]

The drawing is a cross-sectional view of a valve incorporating the invention, shown within a system of fluid circuits. 10... temple, 11... detent mechanism, 12
... Valve body, 14, 15, 16 ... Cylindrical hole, 18, 19 ... Inlet hole, 20, 21 ...
...Exit hole, 25...Spool, 56...
...Spiral spring.

Claims (1)

[Claims] 1. A valve body having a cylindrical hole, a fluid inlet hole and an outlet hole that communicate with the cylindrical hole, and a first valve body that is reciprocably disposed within the cylindrical hole and that communicates between at least the inlet hole and the outlet hole. a spool movable between an operating position and a neutral position for blocking said communication; centering spring means for urging said spool to said neutral position; and a plurality of annular grooves provided around the outer periphery of an extension of said spool; a plurality of balls mounted within the valve body surrounding the spool extension to engage the groove; and a spool extension engaging the balls and forcing the balls into the groove. between an annular member extending therearound, a piston slidable in the axial direction of the valve body within an axial hole provided in the spool extension side end of the valve body, and the annular member and one end of the piston; a fluid passageway communicating with the other end of the piston within the axial bore; responsive to a pressure force that urges the annular member into camming engagement with the ball to maintain the spool in the operative position against the force of the centering spring means; A fluid valve configured to release a biasing force on the annular member in response to a fluid pressure less than the fluid pressure, thereby allowing the valve spool to be moved to a neutral position by the centering spring means.