US 3782404 A
A directional control valve is provided having a pair of standard work positions and a pair of extreme work positions and having a pressure compensating piston arranged between an input and a parallel input line controlling the flow to said control valve, said compensating valve acting as a check valve when the control valve is in its extreme positions and a flow dividing and control valve between the pressure compensating valve and an overflow outlet for delivering excess fluid to a separate load circuit.
Description (OCR text may contain errors)
United States Patent [191 Hodgson [451 Jan. 1,1974
[ ADJUSTABLE, METERED, DIRECTIONAL FLOW CONTROL ARRANGEMENTS  Inventor: Robert F. Hodgson, Canfield, Ohio  Assignee: Commercial Shearing lnc.,
Youngstown, Ohio  Filed: June 14, 1972  App]. No.: 262,460
 US. Cl. 137/101, 137/115, 137/118, 137/117  Int. Cl. G05d 15/00  Field of Search 137/101, 114, 115, 137/117, 118
 References Cited UNlTED STATES PATENTS 3,179,120 4/1965 Erickson et a1 137/101 3,363,516 l/1968 Hubbard 137/101 X 3,410,295 1l/l968 Malott 137/117 X 3,602,104 8/1971 Stremple 137/117 X 3,411,416 11/1968 Herd etal. 137/117X 3,455,210 7/1969 Allen 137/117 X 3,465,519 9/1969 McAlvay et a1. 137/117 X 3,561,327 2/1971 Stremple 137/115 X 3,703,186 11/1972 Brewer 137/118 X Primary ExaminerWilliam R. Cline Attorney-Buell et a1.
 ABSTRACT A directional control valve is provided having a pair of standard work positions and a pair of extreme work positions and having a pressure compensating piston arranged between an input and a parallel input line controlling the flow to said control valve, said compensating valve acting as a check valve when the control valve is in its extreme positions and a flow dividing and control valve between the pressure compensating valve and an overflow outlet for delivering excess fluid to a separate load circuit.
6 Claims, 2 Drawing Figures PATENTEDJAN 4 3.782.404
Steering Valve 50 Implement V I I Valve ADJUSTABLE, METERED, DIRECTIONAL FLOW CONTROL ARRANGEMENTS This invention relates to adjustable, metered, directional flow control arrangements and particularly to a flow control arrangement for delivering pressure fluid to a steering circuit and a working circuit for vehicles of the loading and excavating type.
The problems inherent in controlling the flow of fluid from a single pump to both a metered demand circuit such as a steering circuit and a fully demand circuit such as a loading circuit as well known. This is, however, a type of application frequently encountered in vehicles of the loading and excavating types which have hydraulic steering and hydraulic implement (bucket) systems.
Directional control valves for controlling hydraulic fluid flow to and from a fluid actuated operator are old and well known. Such valves are commonly used to deliver fluid to a piston and cylinder or other form of fluid motor and are quite satisfactory for such purposes where the valve is fully actuated to an open or a closed position. Valves of this type are not, however, adapted to provide a controlled metered flow to or from a fluid motor to operate the actuator at reduced or varied speeds. In general, the conventional control valve will produce a comparatively large change in flow rate for a very small change in position.
This problem has been recognized by others in this art and attempts to solve the problem have been proposed in the patent literature. In Herd et al. U.S. Pat. NO. 3,41 1,416 a flow control arrangement is provided which overcomes some of the difficulties inherent in conventional control valves. Unfortunately, the arrangement of US. Pat. No. 3,41 l,4l6 is adversely affected when an additional load circuit is connected to receive excess flow from its pressure compensating valve. Back pressure at this point, due to the additional load circuit, will prevent it from regulating the inlet flow through the spool valve in the manner intended. Allen U.S. Pat. No. 3,455,210 recognizes this problem in Herd et al. and attempts to solve it by by-passing excess fluid flow away from the directional control valve to the additional load circuit without adversely affecting the regulation of the speed of the actuator. However, experience has shown that the system of Allen while an improvement over Herd is subject to instability and poor regulation of flow to the primary actuator.
The principal difference between the Herd patent and the Allen patent lies in the fact that Allen substitutes a priority valve for a flow regulating valve of Herd with both being connected to an adjustable orifice which is controlled by the directional control valve spool movement.
A serious problem in all of these valve structures is that in the event of a malfunction in the system, there is an insufficient supply of fluid to satisfactorily operate the steering circuit. This can result in serious accidents.
The present invention provides an adjustable metered directional flow control arrangement which solves both the problems of the Herd et al. and the Allen patents as well as providing a safety system which will divert all fluid to the steering in the event of a failure or malfunction. The arrangement of this invention provides precisely controlled fluid flow to the primary actuator regardless of the amount of excess flow going to a secondary load circuit. This arrangement is accordingly ideally suited to sue in a combination steering and load circuit for vehicles of the loading and excavating type.
I provide a directional flow control arrangement for selectively operating first fluid operated motors at a controlled speed and supplying overflow to a separate second fluid motor load circuit comprising a pair of spacedfirst and second directional control valve means each having first and second motor ports for connection to the opposite sides of one of said fluid operated motors and operable to provide a restricted inlet flow passage therethrough for passing input pressure fluid to one of said motor ports the first of said valves being connected to said first motor means and having a parallel high pressure passage, the second to said second motor means and return flow passage for passing return fluid from the other of said motor ports, a pair of flow control valves connected to the inlet of each said directional control valve one having an inlet connected to a source of pressure fluid for said fluid motor through the inlet of said first directional valves, a controlled flow outlet port connected to the inlet of said other flow control valve, an excess flow outlet port connected to said parallel passages, valve means between said inlet port and both said outlet ports to control the fluid flow from said inlet to each of said outlet ports, means for operating said valve means in response to the fluid pressure drop across said inlet flow passage through said first directional control valve means to control the division of flow from said inlet port to said outlet ports, said other flow control valve having an inlet connected to said source of fluid pressure through said one flow control valve and an excess flow outlet port connected to said second directional control valve, valve means between said inlet and said outlet ports to control the fluid flow from said inlet to said outlet ports and means for operating said valve means in response to fluid pressure drop across said inlet flow passage through said first directional control valve means to control the division of flow from the inlet means to said outlet means. Preferably the first directional control valve is provided with an extreme position at each end of its spool movement connecting the inlet of the directional control valve in one such position with the parallel path and a first motor port and in the other of said positions connecting the inlet of the directional control valve with the parallel passage and the second motor port, bypassing the flow control valves.
In the foregoing general description, I have set out certain objects, purposes and advantages of this invention. Other objects, purposes and advantages will be apparent from the following description and the accompanying drawings in which:
FIG. 1 is a sectional view of a preferred embodiment of a valve arrangement according to my invention;
FIG. 2 is a schematic view of a steering and implement circuit according to my invention.
Referring to the drawings 1 have illustrated a preferred embodiment of valve structure according to my invention as embodied in a combination steering and implement circuit such as is used on earth moving machines. In the drawings l have illustrated a directional control valve housing 10 having an axial bore 11 carrying a valve member 12. The housing is provided with spaced exhaust chamber 13 and 14 adjacent each end and intersecting bore 11, a pair of work chambers 15 and 16, one adjacent each exhaust chamber and each adapted to be connected to the opposite sides of a fluid motor. Between the two work chambers are spaced parallel passage chambers 17 and 18 connected by a passage 60, sometimes hereafter called the parallel path" and between the parallel passage chambers a pair of inlet chambers 19 and 20 in side-by-side relationship which when connected will sometimes hereafter be called the "open center path." The valve member 12 is hollow at each end to provide a pair of spaced apart internal chambers 21 and 22 extending axially of the valve member and each connected by a separate axial passage 23 and 24 and a separate radial passage 25 and 26 to spaced annular grooves 27 and 28 around the valve member 12 adjacent its mid point. Each of chambers 21 and 22 is provided with two sets of radial passages 2la and 21b and 22a and 22b extending radially to the periphery of the valve member. The radial passages 21a and 21b are spaced apart axially in chamber 21 as are also passages 22a and 22b in chamber 22. Passages 21a and 220 are separated from passages 21b and 22b respectively by check valves 21c and 22:: movable in chambers 21 and 22 respectively and operated by springs 21d and 22d. lnlet chamber 19 is connected to a pump 29 for providing a source of high pressure fluid. lnlet chamber 20 is connected to inlet 30 of flow control valve 31 which is in turn connected to inlet 40 of flow control valve 41. lnlet 30 communicates with bore 32 of valve 31 which is provided with valve member 33 biased to close the bore 32 between the passage 37. The inlet 30 communicates at all times with outlet 34 through annular chamber 31a. The bias is provided by a spring 35 and by a fluid pressure line 36. lnlet 40 communicates with bore 42 of valve 41 which is provided with valve member 43 biased to close outlet 44 and prevent communication of outlet 44 with inlet 40. The bias is provided by spring 45 and fluid pressure line 46. Fluid pressure lines 36 and 46 connect to a common annular manifold 47 in bore 11 of the directional control valve 10. Outlet 44 is connected to implement directional control valve 50 through its inlet where it joins the input line 51 from a second pump 52 providing an independent source of high pressure fluid.
The operation of the structure of FIGS. 1 and 2 as applied to a combination steering and implement control arrangement is as follows assuming a pump pressure available in excess of 60 psi. When there is no flow of pressure fluid in the system and the directional control valve for steering control is in the neutral position, everything will be essentially as shown in the FIG. 1. The upper of the two flow control pistons will be to the right, and the lower will be to the left, both of which are spring biased. When the pump is started up and the spool 12 remains in neutral, the flow will be around the spool 12 and around the first 33 of the two flow control spools through annular chamber 31a to the annular groove 43a or reduced diameter area of the second spool at which time it is blocked monentarily. The second spool 43 will then shift towards the right at approximately 60 psi because of the flow of fluid in line 43b and begin to bypass oil on to the rest of the circuit through outlet 44, which in this case is primarily the lifting circuit for the implement as represented by valve 50. The spring .end of that flow regulating spool is vented to the reservoir through the line 46 of the spool as previously discussed. Any requirement of the implement circuit then can be accommodated by the flow through this valve on to the implement circuit, either by its singular supply from this pump or in conjunction with any other pump 52 which may be in this total circuit. The 60 psi drop will quickly disappear if the pressure rises above that since the spring end is vented to the reservoir 60 and there will be very little pressure drop then through this first valve in the circuit which we will call the steering valve. At any time the imple ment circuit 50 is used by itself, there will be no appreciable or measurable loss of fluid in the steering circuit since that spool is in neutral and in all true sense of the word it could be considered a closed center valve at this time.
The upper of the two flow regulating spools 33 is spring biased towards the right and also is vented to the reservoir by line 36 when the directional control valve spool 12 in this steering valve is in neutral; therefore, it will act as a check in certain cases. If we assume that the upper of the two flow regulating spools 33 has a 40 pound spring 35, it would be normal then for this spool 33 to shift to the left and close off any passage from the main open-center path 19, 20 to the parallel path 17, 18, 60 from which power can be directed to either work port 15 or 16 because of the fact that the spring end is vented to the reservoir which is at less than 40 or 60 psi. When the directional control spool 12 is indexed towards the right, the passages within the spool will be aligned so that the parallel chamber 15 immediately adjacent to this upper flow regulating valve 31 will be connected through to port 15 except for the spring loaded check valve 210 within the spool. At that time, the passage 23 within the spool 12 is also connected to the back of both of the flow regulating valves 31 and 41, both the upper and the lower, so that they then become pressure compensated. In effect, they are pressure compensated in an opposite manner from each other. The lower valve 41 is pressure compensated to regulate the exhausting or excess oil. The upper outlet 37, to the left, will actually be shut off and will not start to open up until communication between the parallel path 17, 60, 18 the center of the spool 12, the connecting or vent path and the back of the spool 33 is completed at which time the circuit is complete and both ends of the spool are connected together via the previously mentioned route. At this moment the spring 35 will then push the spool to the right opening a path around the spool from the main open-center supply route from the pump to the parallel supply path 60 in the valve itself. As soon as flow starts, there will be a pressure drop from this main supply path to the parallel path, and there will be a second pressure drop from the parallel path 60 into the spool, both of which will affect the total amount of flow being permitted to pass in that direction and ultimately to port 15. For any intermediate position of the directional spool, a pressure drop from the parallel passage 60 into the center of the spool will be established. This will be matched by the pressure drop established across the spool and the edge of the housing metering the oil from the opencenter passage to the parallel path 60 in opposition to the spring 35. However, since there is assumed an established 60 psi pressure differential available, the spool will shift beyond that point and attempt to put more oil to the parallel passage. Now, the 40 psi drop will definitely be between the spool 33 OD and the spool 33 ID at the parallel passage 60 opening. The spool 33 will continue to shift to the left until a 20 psi drop is established from the open-center passage to the reduced diameter area of the spool 33, thereby establishing a total of 60 psi pressure drop from the opencenter passage to the center of the directional spool 12. This will be balanced by the spring 35 and the differential pressure across the respective ends of the flow regulating spool 33. Any tendency of the external pressure to vary the amount of oil directed towards port will be automatically adjusted to compensate for this by the shifting of the flow regulating spool 33. In short, the spool 33 meters flow in to the parallel path 60. It can be seen that the only oil taken from the (open-center) inlet chambers 19 and path in the steering device will be that oil which is required and regulated by the steering directional control valve spool 12 and its associated compensator valve 31.
The shifting of the directional control valve spool 12 to the other side (left) will provide power to port 16 in like manner as that previously described for port 15. The oil returns from an exhaust port 13.
In the event that the steering system requires a higher pressure than the implement circuit, the operation will be the same whether this be higher than the operating pressure of the implement circuit or higher than the open-center pressure when there is no demand on the implement circuit. At this time, the second or lower pressure compensated spool 41 is also connected to the respective side of the spool that is expecting power for the port, and it will load at whatever pressure is required by he steering circuit.
An additional feature which is available in the structure of this invention is the fact that the spool 12 can be shifted over and beyond that normally required for metered control. When this is done in either direction from neutral position, the full diameter of the spool which up to this point has been separating the opencenter path from the parallel path is now shifted off to the right so that it blocks the open-center path 19, 20 completely at that point and opens the direct passage from the inlet 19 to the parallel path 17, 60. At this time all of the oil from the pump will be directed to the parallel path 17, 60 and subsequently to port 15 via the spool 12 and check valve 21c. The lower 41 of the two flow regulating valves is no longer a factor in the circuit. The upper 31 of the two valves will now assume a position as a check valve and block the escape of any oil from the parallel path 17, 60 to the open center 20 and thereby preventing the oil from subsequently be coming a loss to the circuit. When the spool 12 is moved to the extreme left position, there is a passage opened up between the open center 19 or pump inlet and the parallel path 17, 60 at the same time that the full diameter of the spool at land 12a blocks the opencenter path 20.
it can readily be seen from FIG. 1 that the metered or regulated flow will be available to the steering valve during under all normal conditions at whatever pressure is necessary. In the event of a malfunction of either the lower or upper flow regulating device, operation of the spool 12 to either extreme position will divert 100 percent of the oil into the steering circuit directly, thereby providing a safety feature that would not be available in a purely pressure compensated operation.
The implement valve 50 may be of the more common open-center type or it may be pressure compensated since this method of control does not affect performance of the steering valve. The steering valve 10 will take whatever oil is necessary at its pressure regardless of what is going on at the balance of the circuit. In addition, the steering circuit takes only that oil which it needs unless an emergency occurs at which time all of the oil from pump is made available.
In the foregoing specification I have set out a present preferred embodiment of my invention, however, it will be understood that this invention may be otherwise embodied within the scope of the following claims.
1. A directional flow control arrangement for selectively operating a first fluid motor in two directions at a controlled speed and supplying overflow to a separate second fluid motor load circuit comprising a directional control valve means (10, 11, 12) having an inlet means (19) and an outlet means (44) a parallel high pressure passage and first (15) and second (16) motor ports for connection to the opposite sides of said first fluid operated motor, said directional control valve including a movable valve member (12) having annular grooves and axial bores cooperating to provide a restricted inlet flow passage therethrough for passing input pressure fluid to one of said motor ports (15, 16) and return flow passage (21, 21a-c; 22, 22a-e) for passing return fluid from the other of said motor ports, to an adjacent exhaust chamber (13, 14) a pair of flow controls valves (31, 41) connected to the inlet (19) of said directional control valve (10) one having an inlet (30) connected to a source of pressure fluid for said first fluid motor through the inlet (19) for said directional control valve, an outlet port (34) continously connected to both the inlet (30) of the said one (31) and to the inlet (40) of the other flow control valve (41 a parallel flow outlet port (37) connected to said parallel passage (60), valve member (33) in said one valve (31) between said inlet port (30) and said parallel outlet port (37) to control the fluid flow from said inlet (30) to said parallel flow outlet port (37), pressure responsive means (35, 36) for operating said valve member 33 in response to the fluid pressure drop across said inlet flow passage through said directional control valve, pressure sensing means (23-28, 36, 46, 47) acting on said valve member to control the division of flow from said inlet port (30) to said outlet ports (37, 44), said other flow regulating valve (41) having an inlet (40) connected to said source of inlet pressure (19) around said one flow control valve (31) and an excess flow outlet port (44) connected to said separate load circuit (50), a valve member (43) in said other valve (41) between said inlet (19) and said excess flow outlet ports (44) and pressure responsive means (45, 46) for operating said valve means in response to fluid pressure drop across said inlet passage (19) through said directional control valve means.
2. A control valve as claimed in claim 1 wherein the valve member of the directional control valve is movable in a bore therein, said valve member being hollow at each end to form chambers therein adapted selectively to communicate through the valve member walls with the inlet port, work ports, an outlet port and the pressure sensing port of the pressure compensating valve.
3. A control valve as claimed in claim 2 wherein said directional control valve member communicates with the pressure sensing port through a passageway between the two chambers in the neutral position and through a passageway in each chamber in each work position.
port to said second fluid motor load circuit when the pressure in the chamber exceeds the biasing means and pressure sensing pressures.
6. A control valve as claimed in claim 1 wherein the directional flow control valve means has an extreme position at each end which directly connects the inlet and parallel passage with one of the motor ports.