US3456671A - Directional control valve - Google Patents

Description

July 22, 1969 H. J. STACEY 5 DIRECTIONAL CONTROL VALVE Filed April 14. 1966 INVENTOR HUGH J. STACEY BY m,m q.amuz&

ATTORNEYS United States Patent 3,456,671 DIRECTIONAL CONTROL VALVE Hugh J. Stacey, Willoughby, Ohio, assignor to Parker- Hannifin Corporation, Cleveland, Ohio, a corporation of Ohio Filed Apr. 14, 1966, Ser. No. 542,487 Int. Cl. GOSd 11/02, 11/16; F17d 3/02 US. Cl. 137-118 11 Claims ABSTRACT OF THE DISCLOSURE A flow divider in which a valve element is movable between first and second positions respectively closing and opening communication between an inlet passage and a first outlet passage, and an orifice plate movable relative to the valve element between first and second positions respectively providing restricted and more restricted communication between such inlet passage and a second outlet passage, such valve element and orifice plate being biased to their first positions by a spring means which is effective upon predetermined pressure drop across the orifice plate to yield to permit movement of the valve element to its second position, and upon predetermined greater pressure drop across the orifice plate, to yield to permit movement of the orifice plate to its second position.

The present invention relates generally as indicated to a directional control valve and more particularly to a directional control valve having a priority flow divider in the inlet passage thereof.

In the case of fork lift trucks, front end loaders, back hoes, and the like it is known to employ fluid motors for operating the lift forks, booms and buckets thereof and, in addition, provision is made for power steering of such equipment. Generally, in the operation of such equipment the power steering circuit, while mostly being used when the fluid motors aforesaid are not being actuated, must have fluid delivered thereto to assure steering control at all times even though any or all of the fluid motors are being actuated. Of course, when the fluid supply is more than adequate for the power steering control, it is desirable that the surplus fluid be available for actuation of the fluid motors.

Accordingly, it is a principal object of this invention to provide a flow divider and priority valve to achieve the foregoing ends, that is, to make available for the priority circuit (e.g. the steering circuit) a predetermined minimum flow of fluid at all times and to make available excess fluid for operating the auxiliary circuit (e.g. the equipment fluid motor circuit).

It is another object of this invention to provide a flow divider and priority valve which is disposed in the path of inlet flow to a directional control valve.

It is another object of this invention to provide a priority flow divider which is operative to conduct a greater amount of fluid to the priority circuit when the directional control valve or valves for the auxiliary fluid motor control circuit are in neutral position than when the latter are in an operating position thereby diverting a greater amount of fluid to the auxiliary control circuit at a time when less fluid is required in the priority circuit.

Other objects and advantages of the present invention will become apparent as the following description proceeds.

To the accomplishment of the foregoing and related ends, the invention, then, comprises the features hereinafter fully described and particularly pointed out in the claims, the following description and the annexed drawing setting forth in detail a certain illustrative embodiment of the invention, this being indicative, however, of but 3,456,671 Patented July 22, 1969 one of the various ways in which the principle of the invention may be employed.

In said annexed drawing:

The single figure is a cross-section view of a directional control valve having a priority flow divider according to the present invention disposed in the pressure inlet passage, such section having been taken in a plane passing through the axis of the valve spool of the directional control valve.

Referring now to the drawing, the directional control valve V herein comprises a housing 1 having a bore 2 in which the directional control valve spool 3 is axially reciprocable to control the operation of a fluid motor (not shown). Said bore 2 is intersected axially therealong by (a) a bypass passage 4 which, at its upstream end, intersects another bore 5 in which the priority flow divider asembly 6 is disposed, and which at its downstream end, communicates with the return port 7 which leads to a fluid reservoir; (b) a pair of pressure feed passages 8; 8 which through the check valves 9; 9 communicate with the portion of the bypass passage which is between the bores 2 and 5; (c) a pair of motor passages 10; 10 for connection with a fluid motor; and (d) a pair of return pasages 11; 11 which also lead to the return port 7.

The housing 1 has a pressure inlet port and passage 12 which intersects the flow divider bore 5, and a priority circuit port and passage 14 likewise intersecting the flow divider bore 5, between the inlet passage 12 and one return passage 11 is a pressure relief valve 15 which opens when the pressure in the inlet passage 12 exceeds a predetermined value.

By way of illustrative example, the spool 3 is of the four-way open center type for controlling a doubleacting fluid motor, not shown, adapted to be connected. with the motor pasages 10; 10. When said spool 3 is in neutral position as shown, the bypass passage 4 is open from its upstream end to its downstream end and both motor passages 10 are blocked from communication with the adjacent pressure feed and and return passages 8 and 11. When the spool 3 is moved downwardly from its aforesaid neutral position, the bypass pasage 4 is closed thereby and the upper pressure feed passage 8 is communicated with the upper motor passage 10 for flow of fluid through the upper check valve 9 into one end of a fluid motor, and the lower motor passage 10 is communicated with the lower return passage 11 for return flow of fluid from the other end of the fluid motor. When the spool 3 is shifted upwardly from its aforesaid neutral position, the lower pressure feed passage 8 is communicated with the lower motor passage 10 for flow of fluid through the lower check valve 9 into said other end of the fluid motor while said one end of the fluid motor is open for return flow of fluid through the upper motor passage 10 which is in communication with the upper return passage 11.

Movable in the flow divider bore 5 is a tubular flow divider member 16 which is biased by the spring 17 to a position shown wherein the openings 18 in said member 16 are blocked by the portion of the bore 5 between bypass passage 4 and inlet passage 12, thus to block communication between the inlet passage 12 and the upstream end of the bypass passage 4.

Movable in said member 16 and biased by the spring 19 against the stop constituted by the snap ring 20 in said member 16 is an orifice plate 21 having a plurality of orifices 23 therethrough for flow of fluid through the tubular spring follower 24 and through the openings 25 in said member 16 which open into the priority passage 14.

The spring 19 has a higher preload than the spring 17 and, therefore, when the pressure drop across the orifice plate 21 exceeds the bias of the spring 17, the flow divider member 16 will commence to move upwardly to progressively uncover the openings 18 to provide increas ing flow of fluid from the inlet passage 12 to the up stream end of the bypass passage 4 and if, at that time, the spool 3 is in neutral position, the excess flow will be returned to a reservoir connected with the return port 7. In the present example, the flow of fluid to the priority circuit via passage 14 may be 16 g.p.m. for example and any excess flow is diverted to the bypass passage 4 for return to a reservoir via return port 7. Such upward movement of the flow divider member 16 will continue until the shoulder 26 thereof engages the spring follower washer 27 of another spring 28, at which time, the combined force of the springs 17 and 28 is greater than the preload force of the orifice plate spring 19, whereupon continued increased pressure drop across: the orifice plate 21 will cause the latter to move upwardly into engagement with the lower end of the follower 24, thus to block all but the center one of the orifices 23.

Such movement of the orifice plate 21 will occur as when the spool 3 is shifted from neutral position to one of its operating positions, whereby pressure will build up in the upstream end of the bypass passage 4 and in the inlet passage 12, and such increased pressure will cause an increased pressure drop across the orifice plate 21 effective to move it as aforesaid thus to restrict the flow of fluid to the priority circuit passage 14 to a lower value and thus make available to the directional control valve a greater portion of the pump capacity. As an example, the flow capacity of the single orifice 23 may only be 4 g.p.m. which will be adequate for power steering during operation of the lift or hoist cylinder of a fork lift truck, front end loader, etc.

At the time that the flow divider member 16 has moved up so that its shoulder 26 engages the spring follower washer 27, the openings 18 thereof provide for substantially full flow from the inlet passage 12 to the upstream end of the bypass passage 4 and when the directional control valve spool 3 is in an operating position there will be a flow of 4 g.p.m. to the priority circuit passage 14 which is adequate for power steering and the like at that time, while yet a major portion of the pump capacity will be available for equipment control circuit operations.

In the event of still further increased pressure drop across the orifice plate 21 after it has engaged the follower 24, both springs 17 and 28 will be compressed further by continued upward movement of flow divider member 16. Such continued upward movement of member 16 begins to progressively and successively close off the openings 25 as they enter the bore 2 above priority circuit passage '14 thus to maintain the desired minimum flow to the priority circuit passage 14 with increased flow for fluid motor actuation.

Other modes of applying the principle of the invention may be employed, change being made as regards the details described, provided the features stated in any of the following claims, or the equipalent of such, be employed.

I therefore particularly point out and distinctly claim as my invention:

1. In combination, a directional control valve com prising a housing having a bypass passage with upstream and downstream ends for connection with a fluid pressure source and a reservoir respectively, a pressure feed passage for connection with a fluid pressure source, a

motor passage for connection with a fluid motor, and a 1 valve member between said motor passage and said pressure feed and return passages to at least one operating position whereat said bypass passage is closed by said valve member and whereat said motor passage is communicated with said pressure feed passage for fluid pressure actuation of such fluid motor; said housing having a pressure inlet passage and another motor passage; orifice means in said housing providing communication between said inlet passage and said another motor passage; a priority flow divider in said housing responsive to increasing pressure drop across said orifice means exceeding a predetermined value effective to progressively open a. passage between said inlet passage and the upstream end of said bypass passage and said pressure feed passage; and means responsive to a predetermined greater pressure drop across said orifice means to substantially decrease the flow capacity of said orifice means whereby substantial fluid flow is available for fluid motor actuation upon movement of said valve member to said one operating position, said priority flow divider comprising a valve element movable in a bore in said housing which is intersected by said inlet passage and another motor passage, and first spring means biasing said valve element to a position closing communication between said inlet and bypass passages; and said orifice means comprising an orifice plate movable in said valve element to decrease the flow capacity therethrough from said inlet passage said another motor passage when moved from a first position ot a second position, and second spring means biasing said orifice plate to said first position; said first spring means yielding upon such predetermined pressure drop across said orifice plate to permit movement of said valve element to progressively open communication between said inlet and bypass passages, and said second spring means yielding upon such predetermined greater pressure drop across said orifice plate to permit movement of said orifice plate to said second position.

2. The combination of claim 1 wherein said valve element, upon yet further increase in pressure drop across said orifice plate, is moved against said first spring means to progressively decrease the flow capacity of passages therein communicating with said another motor passage.

3. The combination of claim 1 wherein third spring means bears on said valve element to yield together with said first spring means in response to yet further increase in pressure drop across said orifice plate thus to permit movement of said valve element to progressively decrease the flow capacity of passages therein communicating with said another motor passage.

4. The combination of claim 1 wherein said orifice plate has a plurality of orifices therethrough; and wherein said valve element has a stop therein engaged by said orifice plate in said second position to block fluid fiow through at least one orifice.

5. A flow divider comprising a housing having a bore intersected by an inlet passage for connection with a fluid pressure source and by first and second outlet passages for connection with fluid motors; a valve element movable in said bore between first and second positions respectively closing and opening communication between said inlet passage and said first outlet passage; orifice plate means movable relative to said valve element between first and second positions respectively providing restricted and more restricted communication between said inlet passage and said second outlet passage; and spring means biasing said valve element and said orifice plate means to their respective first positions and eifective, upon predetermined pressure drop across said orifice plate means to yield to permit movement of said valve element to said second position and, upon predetermined greater pressure drop across said orifice plate means to yield to permit movement of said orifice plate means to said second position.

6. The flow divider of claim 5 wherein said spring means comprises first and second springs respectively biasing said valve element and said orifice plate means to said first position. v

7. The flow divider of claim 5 wherein said valve element is moved to a third position to restrict flow of fluid from said inlet passage to said second outlet passage via said orifice plate means upon further increase in pressure drop across the latter when in said second position.

8. The flow divider of claim 5 wherein said spring means comprises first and second springs respectively biasing said valve element and said orifice plate means to said first positions; and wherein a third spring bearing on said valve element yields to permit movement of said valve element to a third position to restrict flow of fluid from said inlet passage to said second outlet passage via said orifice plate means upon further increase in pressure drop across the latter when in said second position.

9. The flow divider of claim 5 wherein said orifice plate means has a plurality of orifices therethrough; and wherein said valve element has a stop therein engaged by said orifice plate means in said second position to block fluid flow through at least one orifice.

10. The fiow divider of claim 8 wherein said valve element has a shoulder against which said third spring bears upon movement of said valve element to said second position, and means are provided for maintaining said third spring out of engagement with said shoulder during movement of said valve element between said first and second positions, whereby only said first spring biases said valve element during such movements between said first and second positions.

11. In combination, a directional control valve comprising a housing having a bypass passage with upstream and downstream ends for connection with a fluid pressure source and a reservoir respectively, a pressure feed passage for connection with a fluid pressure source, a motor passage for connection with a fluid motor, and a return passage for connection with a reservoir; a valve member movable in said housing from a neutral position whereat said bypass passage is open through said valve member and whereat communication is blocked by said valve mmeber between said motor passage and said pressure feed and return passages to at least one operating position whereat said bypass passage is closed by said valve memher and whereat said motor passage is communicated with said pressure feed passage for fluid pressure actuation of such fluid motor; said housing having a pressure inlet passage and another motor passage; orifice means in said housing providing communication between said inlet passage and said another motor passage; a priority flow divider in said housing responsive to increasing pressure drop across said orifice means exceeding a predetermined value effective to move to a position progressively opening a passage between said inlet passage and the upstream end of said bypass passage and said pressure feed passage; and means responsive to a predetermined greater pressure drop across said orifice means to move said orifice means relative to said priority flow divider to a position substantially decreasing the flow capacity of said orifice means, whereby substantial fluid flow is available for fluid motor actuation upon movement of said valve member to said one operating position.

References Cited UNITED STATES PATENTS 2,859,762 11/1958 Banker 137108 3,160,167 12/1964 Martin 137596.12

WILLIAM F. ODEA, Primary Examiner H. M. COHN, Assistant Examiner US. Cl. X.R.

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