US3592216A

US3592216A - Flow control valve

Info

Publication number: US3592216A
Application number: US757960A
Authority: US
Inventors: Kenneth G Mcmillen
Original assignee: Borg Warner Corp
Current assignee: Borg Warner Corp
Priority date: 1968-09-06
Filing date: 1968-09-06
Publication date: 1971-07-13
Anticipated expiration: 1988-07-13
Also published as: GB1279319A; ES371132A1; DE1944129B2; DE1944129A1; FR2017503A1; BE738466A; NL6913629A; SE347323B; ZA695982B

Abstract

A flow control valve for use with a manual control valve controlling a hydraulic motor, the flow control valve having a piston therein having a variable orifice and an optional fixed orifice connected between the variable orifice and the inlet of the manual valve. The flow control valve is controlled by a variable orifice established by the manual valve between the inlet to the manual valve and an outlet port of the manual valve connected to the hydraulic motor. The flow control valve includes a pressure chamber connectable to the load-actuating pressure of the manual valve whereby the variable orifice will be sized to provide a pressure in accordance with the work port pressure and the optional fixed orifice providing a maximum flow limit for the control valve. An orifice is provided in the connection between the work ports and the pressure chamber of the flow control valve and the pressure chamber is further connected to a relief valve whereby when the relief valve is open the pressure in the pressure chamber will be stabilized allowing movement of the flow control valve to limit the pressure supplied to the manual valve when the load-actuating pressure exceeds the predetermined maximum pressure limit of the manual control valve whereby a maximum pressure value is established for the hydraulic motor.

Description

United States Patent [72] inventor Kenneth G. McMillen Primary Examiner- Laverne D. Geiger Wolcottville, Ind. Assistant Examiner-David .1. Zobkiw [21] Appl. No. 757,960 Attorneys-Donald W. Banner, Lyle S. Motley, C. G. Stallings [22] Filed Sept. 6,1968 and William S. McCurry [45] Patented July 13, 1971 [73] Assignee Borg-Warner Corporation Chi [[1, ABSTRACT: A flow control valve for use with a manual control valve controlling a hydraulic motor, the flow control valve having a piston therein having a variable orifice and an optional fixed orifice connected between the variable orifice and the inlet of the manual valve. The flow control valve is controlled by a variable orifice established by the manual valve [54] PLOW CONTROL VALVE between the inlet to the manual valve and an outlet port of the 33 Claims, 6 Drawing Figs manual valve connected to the hydraulic motor. The flow control valve includes a pressure chamber connectable to the U.S. load-actuating pressure of the manual valve whereby the vari. 91/433, 91/448 able orifice will be sized to provide a pressure in accordance [51] lnLCI ..G05d 11/00, with the work port pressure and the optional fi d ifi F15! 11/10 providing a maximum flow limit for the control valve. An ori- [50] Field of Search 137/108, fi is provided in the connection between h work pol-ts and 115; 91/412, 433, 434, 448 the pressure chamber of the flow control valve and the pres- [56] References Chad sure chamber is further connected to a relief: valve whereby when the relief valve 15 open the pressure in the pressure UNITED STATES PATENTS chamber will be stabilized allowing movement of the flow con- 2,467,S76 4/1949 Zimmermann.. 137/115 X trol valve to limit the pressure supplied to the manual valve 2,852,918 9/1958 Schwary I 137/108 X when the load-actuating pressure exceeds the predetermined 2,971,523 2/1961 Dudley 137/1 15 X maximum pressure limit of the manual control valve whereby 3,179,040 4/1965 Seltzer... 91/412 X a maximum pressure value is established for the hydraulic mo- 3,405,608 10/1968 Teale 91/412 tor.

.r\. 27a 79 T 36 ro 0TH E12 vAtvEs FLOW CONTROL VALVE SUMMARY OF INVENTION The improved flow control valve of the present invention incorporates structure providing several functions in the fluid circuit which are not available with flow control valves as known in the prior art. The flow control valve responds and will further control the pressure supplied to the manual control valve by means of a pressure chamber connected to the load-actuating pressure of the manual control valve whereby regardless of the amount of excess pressure admitted to the flow control valve a pressure will be admitted to the manual control valve in accordance with the requirements of the motor. The flow control valve will further provide a low standby pressure to the manual valve when the manual valve is in its neutral position even though the system pressure may be much higher at the time. The flow control valve further will respond to a load-actuating pressure greater than the pressure supplied to the flow control valve from the source of pressure thereby interrupting communication between the motor and the source so as to act as a load check valve. The flow control valve optionally may have further a relief valve connected to the pressure chamber and an orifice in the connection between the work ports and the pressure chamber whereby a maximum pressure limit for the motor is provided.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view of a control circuit embodying the principles of the present invention;

FIG. 2 is a modified form of a portion of the control system of FIG. I incorporating an improved flow control valve;

FIG. 3 is a modified form of a portion of the control circuit of FIG. 1;

FIG. 4 is a view illustrating a variable displacement pump as a fluid supply for the system of FIG. 1;

FIG. 5 is a modified form of a portion of the control circuit of FIG. I; and

F IG. 6 is a modified form of the control valves of the circuit of FIG. I.

The present invention comprises a control system for a plurality of hydraulic motors which is adapted to supply pressure to the motors insuring that pressure slightly in excess of that which is needed by a particular motor will be supplied to the motor and the circuit includes means to signal the supply source of the highest load-actuating pressure of any of the motors required at any give time. The control valves may further include an improved flow control mechanism to'ensurethat, regardless of the pressure of the fluid supply, pressure will be supplied to a particular motor at a pressure level as required by that motor.

Referring to FIG. I, the main components of the present control circuit 10 are schematically illustrated. Control circuit 10 includes a source of fluid supply 11, an inlet section 12, a control valve section 13 and a control valve section I4.

In FIG. 1 the supply section as illustrated includes a fixed displacement pump 16, the inlet section 12 includes a fluid pressure responsive means or bypass valve 18 and a relief valve I9. Valve section 13 includes a control valve 21 for controlling a hydraulic motor or work cylinder 22. Valve section 14 likewise includes a control valve 25 controlling hydraulic motor or work cylinder 26 and includes a' flow control valve 27. Valve sections 13 and 14 further are provided with control signal supply means or logic means including shuttle valves 31 and check valves 32. In addition, valve section 13 includes'a load check valve 34.

Each of the valves included in the inlet section I2 and valve sections 13 and 14 are illustrated as mounted in a portion of a valve body 35 which may be a common body to all of the valves or each of the sections may be mounted in a separate valve body. A fluid sump 36 is illustrated in various places throughout the control schematic for purposes of illustration although the actual control circuit would include a single sump 36.

Referring the the inlet section 12, bypass valve 18 includes a piston 40 engageable with a tapered seat 41 provided within a bore 42 in the valve body 35. A spring 44 engages piston 40 urging it toward engagement with seat 41. The piston 40 divides the bore 42 into a chamber 46 and a chamber 47. Relief valve 19 includes a ball poppet 48 and a spring 49 urging the ball to a position engaging a seat 50 in the valve body 35. Bypass valve 18 has its chamber 46 connected to the pump I6 by means of a fluid supply conduit 55. When piston 40 moves to the left a connection is opened between chamber 46 and sump 36 through a conduit 56. Relief valve 19 is connected to chamber 47 of the bypass valve 18 by a conduit 58 and the interior of the relief valve 19 is connected to sump 36 by a conduit 59. Chamber 47 of bypass valve 18 is connected to a control signal conduit 60.

Valve sections 13 and 14 are identical with the exception that in valve section I4 the load check valve 34 is replaced by the flow control valve 27. The description will therefore relate, insofar as the control valve-itself is concerned, to one of the valves, common numbers being given to each valve since the construction and operation of the control valves 21 and 25 y is identical. Further, it will be understood from the description given that additional valves can be provided in the circuit beyond the two illustrated depending on. the number of hydraulic motors to be controlled.

Control valves

21 and 25 each include a pair of

motor ports

65 and 66 which are connected to opposite ends of the

motors

22 or 26 by conduits'67 and 68 respectively.

Control valves

21 and 25 further include an inlet port 70, at least one exhaust port 71, and control-

ports

73 and 74.

A conduit 78 connects the inlet port 70 of control valve 21 to load check valve 34 and inlet port 70 of control valve 25 to flow control valve 27 A conduit 77 connects load check valve 34 and flow control valve 27 with the fluid supply conduit 55. A conduit 79 connects exhaust ports 71 to the sump 36. The fluid-actuated valve means or shuttle valve 31 for each of the

control valves

21 and 25 is a three-port

valve having ports

80, 81 and 82 and a poppet or ball 85. Ports and 82 are connected by conduits 83 and84 respectively to the

control ports

73 and 74 and port 81 is connected to the check valve 32 by conduit 86. Check valves 32 are connected by a conduit 88 with the control signal conduit 60. A conduit 87 therein connects flow control valve 27 to conduit 86. Orifice 89 is provided in the control signal conduit 60 near bypass valve 18.

OPERATION OF THE CONTROL SYSTEM Each of the control valves here illustrated, namely

valves

21 and 25, are of identical structure to the improved valve shown in US. Pat. No. 3,526,247, issued Sept. 1, 1970, of common assignee, for which, reference may be had for a detailed description of the control valve.

As illustrated in FIG. 1, there is provided a control valve for each motor to be controlled. There may be as many control valves and motors connected to the fluid supply conduit 55 and the control signal conduit 60 as desired. Each of the control valves is a three-position valve including a neutral position illustrated in the center thereof and power positions on the left and right sides thereof. In the neutral position illustrated in the center of

control valves

21 and 25 inlet port 70 and

work ports

65 and 66 are blocked.

Control ports

73 and 74 are connected to the sump by conduit 79 when the control valves are in the neutral position.

In operation, pump pressure is supplied to conduit 55. The pressure in conduit 55 will be supplied to a motor through the

conduit

77 and 78 when one of the

valves

21 or 25 is moved to its left or rightposition. If, for example, valve 21 is moved to its power position on the left side thereof, pressure will be supplied through conduit 78 from the inlet port 70 through avariable orifice to motor port 65 to actuate the motor 22. At-the same time, motor port 65 as illustrated will also be connected to the control port 73 and thus through conduit 83, port 80, shuttle valve 31, conduit 86, check valve 32, conduit 88, and

into the control signal conduit 60. If the pressure in the control signal conduit 60 is already higher than that developed at the motor port 65, check valve 32 will remain closed. However, if the pressure in control signal conduit 60 is lower, the pressure supplied to motor 22 through motor port 65 will be communicated by conduit 60 to chamber 47 of bypass valve 18. Thus the bypass valve 18 will be urged to the right with a pressure reflecting the motor port pressure at valve section 13. If the pump pressure exceeds the control signal pressure in chamber 47 by more than the force of the spring 44 (for example if a 50 p.s.i. spring is used) and the control signal conduit has a pressure of 1,500 p.s.i. therein, the valve piston 40 will move to the left at a valve of 1,500 p.s.i. in supply conduit 55 thereby maintaining the pressure in conduit 55 at 50 p.s.i. above the highest load actuating pressure of any of the

control valves

21, 25 or any additional valve.

At the same time, as the connections are made between I inlet port 70, motor port 65 and control port 73, connection is made between the other motor port 66, exhaust port 71 and control port 74. Thus the opposite side of motor 22 and the control port 74 will be connected to the sump through conduit 79, thus allowing the motor to be moved by pressure from motor port 65. Although the showing in FIG. 1 is schematic, it will be understood that when the valve 21, for example, is moved to its power position on the left side thereof, the variable orifice illustrated in the connection between

ports

70 and 65 may be varied in size by the operator to control the rate of actuation of the motor 22 and since the bypass valve 18 in effect maintains a constant pressure drop across this variable orifice, the valve 21 may be easily operated to accurately control the speed or rate of actuation of motor 22.

If the valve 21 is moved to its power position shown on the right side thereof, as will be seen from the schematic illustration, the inlet port 70 is connected to the motor port 66 through a variable orifice and also to the control port 74 to actuate the motor 22 in the opposite direction. Thus again, a control port 74 is connected to the motor port 66 which is communicating fluid pressure to the motor and the pressure in port 66 will thus be communicated through conduit 84, shuttle valve 31, conduit 86, check valve 32, and conduit 88 to the control signal conduit 60. At the same time as illustrated in FIG. 1, the motor port 65 will be communicated to the sump 36 through exhaust port 71 as will conduit 83. As in the above description, manual control valve 21 may then be moved to establish an orifice size between inlet port 70 and motor 66, the bypass valve 18 maintaining a constant pressure drop across the orifice whereby reliable and consistent control of the speed or rate of actuation of motor 22 is provided.

The shuttle valve 31 shown in each of the valve sections communicates to conduit 86 the load-actuating pressure preselected by the control valve position. The shuttle valve is displaced by the preselected load-actuating pressure to a posi tion preventing communication of this pressure with sump through conduit.79, forming together with the

control ports

73, 74 and

conduit

83, 84 what may be considered as a first logic system. Check valves 32 as illustrated in FIG. 1 connected in a parallel arrangement with conduits 88 and control signal conduit 60, may be considered a second logic system which will connect the highest load actuating pressure supplied by any of the first logic systems to the control signal conduit 60. Thus a logic means is provided including the first and second logic systems by means of which the highest load-actuating pressure in the system will be communicated to conduit 60 to insure that adequate pressure will be supplied by the pump to meet the requirements of the motor having the highest pressure requirements.

At times in circuits of the type described it may be advantageous to provide a constant pressure drop between inlet port 70 and

motor ports

65 or 66 thereby establishing a constant flow rate for a selected orifice independent of fluctuation in system pressure. To provide this function, the flow control valve 27 is provided as viewed in FIG. 1. Flow control valve 27 of FIG. 1 is illustrated in block form to show that flow control valves of known types may be incorporated in the improved control circuit of FIG. 1.

Referring to FIG. 2, an improved form of flow control-valve is illustrated. The improved flow control valve 27a includes a piston 91 mounted in a bore 92 in the valve body 35. Piston 91 comprises a generally hollow cylinder having a barrier portion 94 and further having a pair of

ports

96 and 97 directly opposite one another and a pair of

ports

98 and 99 directly opposite one another. Provided in the valve body 35 is a pair of ports 101 and 102 and a large port 103 defining a pressure chamber 104. Barrier portion 94 and piston 91 further define a pressure chamber 105 on the left side of barrier portion 94. Port 101 of the flow control valve is connected to the supply pressure conduit 55 by conduit 77. Port 102 is connected by conduit 78 with the inlet port 70 of control valve 25. A spring 107 is provided urging the piston 91 to the left as illustratedin the drawing.

Barrier portion 94 includes a surface 108 in chamber 105 and a surface 109 in chamber 104. Surfaces I08 and 109 define together with the terminal ends of the piston 91 pressure-responsive areas in each of the

pressure chambers

104 and 105.

Relief valve 28 includes a poppet or ball 1 l0 engaging a seat 111 and is urged into engagement with the seat by spring 112. Relief valve 28 is connected to the pressure chamber 104 by a conduit 113. The interior of the relief valve 28 is connected to the sump 36 by conduit 114. The flow control valve has its pressure chamber 104 connected to conduit 86 through an orifice 116.

Flow control valve 27a serves many functions in its operation in the valve section 14. It acts as a maximum flow limit, it acts to maintain a constant pressure drop across the variable orifice established in the control valve 25, it operates to regulate the fluid pressure to a desired maximum to be supplied to the motor 26, it also acts as a load check valve to prevent backflow when the load-actuating pressure is equal to or greater than the system pressure from conduit 77, and also supplies a low standby pressure to the control valve when the control valve is in the neutral position.

The flow control valve 270 includes the

port

98 and 99 which may optionally be sized to establish a maximum flow limit through the flow control valve 27. The

ports

96 and 97 in cooperation with the right edge of port 101, as viewed in FIG. 2, will establish a variable-size orifice and meter fluid from the conduit 77 into conduit 78 to the inlet port 70 ofthe control valve. The spring 107 tends to move the piston 91 to a position to the left. Since the pressure-

responsive areasin chamber

104 and 105 are of equal area, the pressure being admitted into chamber 105 through

ports

96 and 97 must exceed the pressure in chamber 104 by an amount determined by spring 107 to move the piston to the right to establish an orifice size and meter fluid through the

ports

96 and 97. Since the pressure chamber 104 is connected to conduit 86 the pressure in chamber 104 will be the pressure supplied by the first logic system (shuttle valve 31 and conduits 83 and 84) of the control valve which will be the load-actuating pressure in the valve section 14.

Thus when the supply conduit supplies pressure to the flow control valve exceeding the motor port pressure by an amount determined by the force of spring 107 and the piston 91 will move 35 the right to reduce the size of the orifice through

ports

96 and 97 and meter fluid at a reduced pressure into the inlet port 70. Thus, if the motor port pressure is 1,500 p.s.i. and the spring exerts a force equivalent to 35 p.s.i. when the pressure in conduit 55 is in excess of 1,535 p.s.i., the piston will move to restrict the orifice size until the pressure in chamber 105 is reduced to 35 p.s.i. above the load pressure.

Flow control valve 270 is thus adapted to maintain a con stant pressure drop across the variable orifice in the valve 25 whereby the motor 26 may easily be controlled by varying the variable orifice in the control valve 25. The flow control valve 27a further includes a relief valve 28. Relief valve 28 will serve to limit the pressure in the pressure chamber 104 to a maximum value thus regulating the pressure supplied to inlet port 70 to a predetermined maximum value. For example, if setting of relief valve 28 is l,600 p.s.i., when the pressure exceeds 1,600 p.s.i. the relief valve 28 opens chamber 104 to sump 36 and a pressure drop across the orifice 116 is established stabilizing the pressure in chamber 104 at 1,600 p.s.i. and allowing the piston 91 to move to the right to restrict the flow of fluid coming into the inlet port 70 and allowing communication between inlet port 70 through

ports

98 and 99 to chamber 104 thereby maintaining the pressure at approximately a 1,600 p.s.i. level in port 70.

In a similar manner to the example described, the flow control valve 270 provides a further advantage of maintaining the pressure in inlet port 70 at a low level determined by spring 107, when control valve 25 is in the neutral position. This is accomplished by the communication of chamber 104 to sump 36 through conduit 86, through shuttle valve 31 and

conduits

83 or 84, thus eliminating the pressure signal from chamber 104. Therefore a pressure of approximately 35 p.s.i. in chamber 105 will move the piston 91 to the right establishing approximately a 35 p.s.i. low standby pressure in the inlet port 70.

A further advantage of the flow control valve 270 is to provide adequate pressure as required by the motor 26 regardless of the pressure in the system. If the pressure at the work cylinder 26 is 1,500 p.s.i., the 1,500 p.s.i. pressure will be established in chamber 104. If the system pressure due to operation of another work cylinder is, for example, 2,000 p.s.i., the 2,000 p.s.i. will be communicated through the

ports

96 and 97 and act on the pressure-responsive area in chamber 105 to move the piston 91 to the right against a resistance of 1,500 p.s.i. plus 35 p.s.i. from spring 107 in chamber 104. Thus the piston 91 will move to the right restricting the amount of fluid admitted through

ports

96 and 97 until the pressure is reduced to approximately 1,535 p.s.i. in the chamber 105. Thus the flow control valve 270 insures that pressure admitted to the inlet port 70 will be approximately 35 p.s.i. above that required at the work cylinder thereby establishing a 35 p.s.i. pressure drop across the variable orifice in the valve 25 between inlet port 70 and

motor ports

65 or 66.

Valve piston 91 also acts as a load check valve when the load-actuating pressure exceeds or is approximately equal to the pressure from the supply conduit 55, the piston will be moved to the left by spring 107 and load-actuating pressure in chamber 104 to prevent flow from inlet port 70 to conduit 55. The piston 91 will remain in this position until pressure in supply conduit 55 is approximately 35 p.s.i. above the load-ac tuating pressure.

Referring to FIG. 3, a modified form of a valve to replace the shuttle valve 31 is shown which comprises a valve 120 which has balls 121 and 122 therein urged apart by a spring 123. Valve I20 acts in a manner similar to shuttle valve 13. Whichever conduit, 83, 84, has the preselected load-actuating pressure signal therein will have its respective ball 121 or 122 moved to allow communication between the

port

80 or 82 and port 81, and will prevent communication between

port

82 and 80. The valve 120 represents an optional form of valve which will work in the present control system.

Referring to FIG. 4, an optional form of pump comprising a variable displacement pump 126 is illustrated for the supply section 11 of FIG. 1. Pump 126 is, for example, of the variable angle swashplate axial piston type which has a fluid pressure responsive means comprising a control piston 127 connected to the supply pressure conduit 55 and a control piston 128 connected to the control signal conduit 60 to adjust pump displacement thereby maintaining pressure in conduit 55 at an approximately constant level above that in control signal 60 in accordance with the pressure requirements.

Referring to FIG. 5, an optional form of second logic circuit is illustrated in that the check valve 32 is replaced by shuttle valves 130. The shuttle valves 130 are connected in series in the conduit 60 each including

ports

131, 132, 133 and a ball 134. The shuttle valves operate similar to the check valves 32 in that the pressure in conduit 60 which is eventually communicated to the bypass valve or unloading valve 18 will be the highest load-actuating pressure at any of the motor ports for any of the motors. For example, when the pressure in conduit 86 in the valve section 13 is higher than the pressure in conduit 60 communicated through port 133, ball 134 will move down to open communication between

ports

131 and 132 admitting the pressure from conduit 86 into conduit 60 to be communicated to the bypass valve 18. When the pressure coming in from conduit 60 to port 133 exceeds that in conduit 86, ball 134 is moved up to provide communication between ports 133.and 132 thus blocking pressure from the valve section 13 from influencing the bypass valve 18. Flow control valves for sections 13'or 14 could also be provided using the shuttle valve 130 by connecting them to the conduit 86 similar to the connection illustrated in FIG. 1.

In the control system described above, with each of the modifications which may be used, the bypass or unloadingvalve 18, when there is nosignal in the controlsignal conduit '60, as for example when each of the control valves 21-, 25 or additional valves are in their neutral position, will operate to provide a low standby pressure as determined by the force of the spring 44. If the force of spring 44 requires 50 p.s.i. to

move the piston 40 from its seat 41, the pump pressure in conduit 55 will be bypassed to the extent to maintain fluid pressure in conduit 55 of 50 p.s.i. thus providing a low pressure at standby.

When all of the control valves are returned to neutral position, the control signal conduit 60 will have a pressure-therein which must be negated so that the bypass valve 18 can establish the low standby pressure. In the system illustrated in FIG. 1, the bypass valve 18 can be constructed such that the pressure in conduit 60 can leak past piston 40 into conduit 56 and to the sump 36. Optionally, a conduit having an orifice: therein and connected between the conduit 60 and sump 36 may be provided to allow the pressure in conduit 60 to be negated and drained to sump.

The second logic system, as illustrated in FIG. 5, having shuttle valves 130 connected in series, is advantageous since it permits conduit 60 to be. connected to sump 36 at a point beyond or within the last valve section. When all the control valves are placed in their neutral position, conduits 86 will be connected to sump 36 through

conduits

83 or 84. Ball 134 of' each of shuttle valves 130 will be maintained by the pressure in conduit 86 in its position blocking conduit 60 from the conduit 86 and thus the control pressure in conduit 60can flow 'through each valve 130 to the sump. If at a particular control valve the ball 134 is in its down position and its conduit 86 is supplying the control pressure in conduit 60, the-control pressure in conduit 60 can then flow to sump through

conduits

86 and 83 or 84 of that particular valve. Thus the series arrangement of the second conduits system in FIG. 5 conveniently provides a means of eliminating the pressure in control signal conduit 60 whereby the bypass valve 18 can establish a low standby pressure:

Referring to FIG. 6, a modified form of control valve is illustrated. Control valve includes a valve spool 141 having? lands 142, 143 and 144 thereon. Similar to the

valves

21 and 25, valve 140 includes motor ports 65 and 66' connected to

conduits

67 and 68, an inlet port 70 connected to conduit 78, and a pair ofexhaust ports 71. The

control ports

73 and 74 are mounted on opposite sides of the inlet port 70. The inlet port 70 has on either side thereof tapered

notches

146 and 147. Ex-- haust ports 71 each has a tapered notch 148 on the side" thereof toward its adjacent motor port.

The valve spool 141 is illustrated in its neutral position. If the valve spool would be moved to the right for example, first the motor port 65 would be connected to control port 73 thusto conduit 86. As the spool 141 is moved further to the right, and notch 146 is uncovered, inlet pressure will be allowed through an orifice defined by the adjacent edge of land 143 and notch 146 into motor port 65 and through conduit 67 to the motor. The motor port 65 is thus placed in communication through control port 73 with conduit 86. Thus the conduit 86 will contain the pressure at motor port 65 which is the load-actuating pressure and will supply this pressure to control signal conduit 60 to influence the bypass valve. As the valve spool 141 is moved to the right notch 148 will be uncovered by land 142. Communicating motor port 66 with exhaust port 71 to exhaust the opposite side of the motor. if the valve spool is moved to the left from its neutral position, operation is the same as before, communication first being established between the motor port 66 and the control port 74, and then communication established across an orifice defined by the right edge of land 143 and tapered notch 147, between the inlet port 70 and motor port 66. Thus at all time with the construction of FIG. 6, conduit 86 will be supplied with the loadactuating pressure of the particular motor port that is being connected to the inlet pressure through the inlet port 70. Due to the improved construction of the valve 140, the need for the shuttle valves 31 or valves 120 is eliminated by providing the

control ports

73 and 74 at a location between the motor ports and the inlet ports as illustrated in FIG. 6. A control valve of the type of control valve 140 may be easily utilized in the control circuit of FIG. 1. Thus in this embodiment the first logic system consists only of the construction and movement of the valve 140.

Various features of the invention have been particularly shown and described; however, it should be obvious to one skilled in the art that modifications may be made therein without departing from the scope of the invention.

lclaim:

1. A control valve working section including a control valve and a flow control valve that are operatively interconnected for controlling the flow of fluid from a source of pressure to a fluid-actuated device, said control valve having a pressure inlet port, an exhaust port, first and second motor ports adapted to be connected to said fluid-actuated device, and a valving element movable from a neutral position to first and second operating positions for controlling fluid communication between said ports by establishing a variable orifice therebetween; said flow control valve having an input port, an output port, a bore intersecting said input port and said output port, and a piston in said bore effective to control fluid communication between said input port and said output port and being movable to a position restricting flow therebetween and also being effective to divide said bore into first and second fluid-responsive chambers, and bias force means opposing the movement of said piston to said flow-restricting position; conduit means interconnecting said output port of said flow control valve to said inlet port of said control valve and said output port of said flow control valve being in communication with the one of said fluid-responsive chambers that is effective to move said piston to a flow-restricting position; logic means effective to connect the other of said chambers to whichever motor port is in fluid communication with said inlet port of said control valve; whereby said piston is moved to said flowrestricting position by the difference between the fluid pressure in said output port and whichever motor port is con nected to said inlet port whenever one of said motor ports is connected to said inlet port so that said flow control valve is responsive to the variable area established by said movable valving element and to the flow and pressure drop from said inlet port to either of said motor ports.

2. The control valve working section as claimed in claim 1 in which said logic means includes a control port in said control valve, conduit means connecting said control port to said other chamber, and said valving element cooperates with said control port by connecting one of said motor ports to said control port when said valving element connects said one motor port to said inlet port.

3. The control valve working section in claim 1 in which said logic means includes two control ports in said control valve, conduit means connecting said control ports to said other chamber, and said valving element cooperates with said control ports by connecting one of said control ports to one of said motor ports whenever said valving element connects either of said motor ports to said inlet port.

4. The control valve working section as claimed in claim 3 in which said control ports are interposed between said inlet port and said motor ports of said control valve.

5. The control valve working section as claimed in claim 3 in which said logic means includes fluid-actuated valve means having two control signal inlet ports, and a control signal outlet port, and said conduit means interconnects said control signal inlet ports to said control ports and said control signal outlet port to said other chamber of said flow control valve.

6. The control valve working section as claimed in claim 5 in which said fluid-activated valve means comprises a threeport shuttle valve.

7. The control valve working section as claimed in claim 1 including an additional means to restrict communication between said input and said output port.

8. A control valve working section as claimed in claim 7 wherein said additional means comprises pressure-responsive means connecting said other chamber and said exhaust port and operative to limit the pressure in said other chamber, whereby a pressure in said input port and in said one chamber exceeding said limited pressure in said other chamber is effective to move said piston to said flow-restricting position.

9. A flow control valve working section as claimed in claim 8 wherein said pressure-responsive means comprises a relief valve.

10. A control valve working section as claimed in claim 7 in which said additional means comprises; a load check position to which said piston is movable by said bias means acting on said piston, means associated with said piston to connect said one chamber to said input port and to isolate said one chamber from said output port, whereby when the pressure in whichever motor port is connected to said inlet port is equal to or greater than the pressure at said input port, said bias means and the pressure in said other chamber will act on said piston to move it to said load check position thereby preventing flow from either motor port through said flow control valve toward said input port. 7

ll. The control valve working section as claimed in claim 10 in which said means associated with said piston comprises a hollow portion thereof.

12. A control valve working section as claimed in claim 7 wherein said logic means includes at least one control port in said control valve connecting said other chamber to the motor port connected to said inlet port.

13. A control valve working section as claimed in claim 12 in which said logic means includes a second control port and fluid-actuated poppet means connecting said other chamber to the motor port that is connected to said inlet port.

14. A control valve working section as claimed in claim 7 wherein said one of said chambers is exposed to the pressure at said inlet port and the fluid pressure in said other chamber is reduced to a low value by said logic means whenever said valving element is in said neutral position, whereby a relatively low value of fluid pressure in said inlet port and said one chamber is effective to move said piston to said flow-restricting position against the combined force of said bias force means and said low value of pressure in said other chamber so that said inlet port is isolated from the fluid pressure in said input port whenever said valving element is in said neutral' position.

15. A control valve working section as claimed in claim 14 in which said logic means includes flow paths established and blocked by said valving element, and said valving element cooperates in the establishing of a flow path from said other chamber to said exhaust port to achieve said low value of fluid pressure in said other chamber when said valving element is in said neutral position.

16. A control valve working section as claimed in claim 10 in which said flow control valve includes a bypass position in which said piston moves further into said other chamber than for flowarestricting position, and said piston is effective in said bypass position to establish a fluid communication path from said output port to a conduit communicating with said exhaust port, whereby the pressure in said output port is limited to that which is necessary to move said piston to said bypass position whenever said valving element is in said neutral position.

17. A control valve working section as claimed in claim 7 in which said logic means includes two control ports associated with said control valve and a three port shuttle valve interconnecting said two control ports and said other chamber.

18 A control valve working section as claimed in claim 17 wherein said connection between said other chamber and a motor port includes a pair of pressure-responsive surfaces on said piston, being effective when said valving element is moved to its neutral position to control the pressure in said other chamber whereby said piston will be moved to a flowrestricting position.

19. A control valve working section as in claim 18 in which said flow control valve piston has a bypass position in which said output port is placed in communication with said exhaust port, said bypass position being the flow-restricting position of said piston established when said valving element is in said neutral position.

20. A control valve working section as claimed in claim 17 wherein said additional means includes pressure-responsive means connected to said other chamber and operative to reduce the pressure in said other chamber in response to the pressure at said motor port exceeding a predetermined value.

21. A control valve working section as claimed in claim 17 wherein said one chamber is exposed to the pressure in said fluid connection between said source and said inlet port in which said additional means comprises a load check position of said piston to which said piston is movable by said bias means acting on said piston, means associated with said piston to connect said one chamber to said input port and to isolate said one chamber from said output port whereby when the pressure at said motor port is equal to the pressure at said input port, said bias means will act on said piston to move it to said load check position preventing flow from said motor ports through said flow control valve toward said input port.

22. A control valve working section as claimed in claim 21 in which said means associated with said piston comprises a hollow portion thereof.

23. A control valve working section including a control valve and a differential pressure sensitive valve that are operatively interconnected for controlling the flow of fluid from a source of pressure to a fluid-actuated device; said control valve having an inlet port, an exhaust port, at least one motor port, a spool bore intersecting said ports, and a valving element movable from a neutral position to first and second operating positions for establishing variable orifice fluid communication between said ports; said differential pressure sensitive valve including an input port, an output port connected to said inlet port of said control valve, a bore intersecting said input port and said output port, and a piston in said bore effective in a first operating position to allow free fluid communication between said input port and said output port and being movable to a second operating position restricting flow therebetween and also being effective to divide said bore into first and second fluid-responsive chambers; means adapted to move said piston to said operating positions including bias means applying a force to said position, and fluid pressure means in one of said chambers, and logic means connecting the other of said fluid-responsive chambers to said motor port in said control valve and being effective to control the fluid pressure in said other chamber as a function of the operating positions of said valving element; whereby when said valving element is in its said neutral position the pressure will be controlled in said other fluid-responsive chamber so that said means adapted to move said piston will move said piston to said second operating position.

24. A control valve working section as claimed in claim 23 wherein said bias means applies a force moving said piston toward said first operating'position, conduit means connecting said output port and the one fluid-responsive chamberthat is effective to move said piston to second operating position, and said logic means is effective to connect said other fluidresponsive chamber to said motor port when said valving element is in said first operating position and effective to connect said other fluid-responsive chamber to said exhaust port when said valving element is in said neutral position.

25. A control mechanism as claimed in claim 24 wherein pressure-responsive means is provided connected to said other fluid-responsive chamber whereby when the pressure at said other chamber exceeds a predetermined amount said pressure-responsive means will be actuated to reduce the pressure in said other chamber whereby said valve member will move to a position to block communication'between said input and output ports.

26. A structure as described in claim 25 wherein said pressure-responsive means comprises a relief valve.

27. A control valve working section as claimed in claim 21 in which said control valve includes first and second motor.

ports; said valving element is effective in said first operating position to connect said first motor port to said inlet port, is effective in said second operating position to connect said second motor port to said inletport, and, is effective in said neutral position to isolate said inlet port from both said motor ports; and said logic means is effective to connect said other chamber to whichever motor port is connected to said inlet port and said logic means is also effective to connect said other chamber to said exhaust port whenever said valving element is in said neutral position.

28. A control valve working section as claimed in claim 27 in which said piston is movable from said first position toa bypass position remote from said first position by fluid pressure in said output port and said one chamber, and said piston is effective in said bypass position to open a communication path between said output port and said exhaust port whereby the fluid pressure in said output port is limited to the value required in said one chamber to actuate said piston to said bypass position.

29. A control valve working section as claimed in claim 24 in which said logic means includes a control port intersecting said spool bore.

30. A control valve working section as claimed in claim 24 in which said piston is movable from said first position to a bypass position remote from said first position by fluid pressure in said output port and said one chamber, and said piston is effective in said bypass position to open a communication path between said output port and said exhaust port whereby the fluid pressure in said output port is limited to the valve required in said one chamber to actuate said piston to said bypass position.

31. A control valve working section as claimed in claim 23 in which said logic means includes a control port intersecting said spool bore.

32. A control'valve working section as claimed in claim 23 in which said piston is movable from said first position to said second operating position and to a bypass position in which said piston opens a bypass path from said output port to a conduit communicating with said exhaust port.

33. A control valve having an inlet port, a motor port and a movable valve means intersecting said ports; a differential pressure sensitive valve having first and second ports, and a movable valve member having first and second pressureresponsive areas; said movable valve member defining a variable restriction flow path between said first and second ports, said first port being connected to a source of fluid pressure and said second port being connected to said inlet port of said control valve and said first pressure-responsive area; means connecting the motor port of said control valve to said second fluid-responsive area to control the pressure applied thereto and bias means associated with said second fluid-responsive port. whereby said inlet port of said control valve is isolated from said source of fluid pressure.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 592 216 Dated y 197]- Kenneth G. McMillen Inventor(s) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 8, line 15, "fluid-activated" should read fluid-actuated Column 9, line 2, after "for" insert said sameline 2, after "flow" cancel "a"; line 66, "position" should read piston Column 10, line 52, "valve" should read value Signed and sealed this 30th day of May 1972.

'(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents FORM po-soso (10-691 USCOMWEDC \LS GOVERHNEN? PRINTNG OFFICE: WI! 0-366-3

Claims

1. A control valve working section including a control valve and a flow control valve that are operatively interconnected for controlling the flow of fluid from a source of pressure to a fluid-actuated device, said control valve having a pressure inlet port, an exhaust port, first and second motor ports adapted to be connected to said fluid-actuated device, and a valving element movable from a neutral position to first and second operating positions for controlling fluid communication between said ports by establishing a variable orifice therebetween; said flow control valve having an input port, an output port, a bore intersecting said input port and said output port, and a piston in said bore effective to control fluid communication between said input port and said output port and being movable to a position restricting flow therebetween and also being effective to divide said bore into first and second fluid-responsive chambers, and bias force means opposing the movement of said piston to said flow-restricting position; conduit means interconnecting said output port of said flow control valve to said inlet port of said control valve and said output port of said flow control valve being in communication with the one of said fluid-responsive chambers that is effective to move said piston to a flow-restricting position; logic means effective to connect the other of said chambers to whichever motor port is in fluid communication with said inlet port of said control valve; whereby said piston is moved to said flow-restricting position by the difference between the fluid pressure in said output port and whichever motor port is connected to said inlet port whenever one of said motor ports is connected to said inlet port so that said flow control valve is responsive to the variable area established by said movable valving element and to the flow and pressure drop from said inlet port to either of said motor ports.

6. The control valve working section as claimed in claim 5 in which said fluid-activated valve means comprises a three-port shuttle valve.

10. A control valve working section as claimed in claim 7 in which said additional means comprises; a load check position to which said piston is movable by said bias means acting on said piston, means associated with said piston to connect said one chamber to said input port and to isolate said one chamber from said output port, whereby when the pressure in whichever motor port is connected to said inlet port is equal to or greater than the pressure at said input port, said bias means and the pressure in said other chamber will act on said piston to move it to said load check position thereby preventing flow from either motor port through said flow control valve toward said input port.

11. The control valve working section as claimed in claim 10 in which said means associated with said piston comprises a hollow portion thereof.

14. A control valve working section as claimed in claim 7 wherein said one of said chambers is exposed to the pressure at said inlet port and the fluid pressure in said other chamber is reduced to a low value by said logic means whenever said valving element is in said neutral position, whereby a relatively low value of fluid pressure in said inlet port and said one chamber is effective to move said piston to said flow-restricting position against the combined force of said bias force means and said low value of pressure in said other chamber so that said inlet port is isolated from the fluid pressure in said input port whenever said valving element is in said neutral position.

16. A control valve working section as claimed in claim 10 in which said flow control valve includes a bypass position in which said piston moves further into said other chamber than for flow-restricting position, and said piston is effective in said bypass position to establish a fluid communication path from said output poRt to a conduit communicating with said exhaust port, whereby the pressure in said output port is limited to that which is necessary to move said piston to said bypass position whenever said valving element is in said neutral position.

17. A control valve working section as claimed in claim 7 in which said logic means includes two control ports associated with said control valve and a three port shuttle valve interconnecting said two control ports and said other chamber. 18 A control valve working section as claimed in claim 17 wherein said connection between said other chamber and a motor port includes a pair of pressure-responsive surfaces on said piston, being effective when said valving element is moved to its neutral position to control the pressure in said other chamber whereby said piston will be moved to a flow-restricting position.

24. A control valve working section as claimed in claim 23 wherein said bias means applies a force moving said piston toward said first operating position, conduit means connecting said output port and the one fluid-responsive chamber that is effective to move said piston to second operating position, and said logic means is effective to connect said other fluid-responsive chamber to said motor port when said valving element is in said first operating position and effective to connect said other fluid-responsive chamber to said exhaust port when said valving element is in said neutral position.

25. A control mechanism as claimed in claim 24 wherein pressure-responsive means is provided connected to said other fluid-responsive chamber whereby when the pressure at said other chamber exceeds a predetermined amount said pressure-responsive means will be actuated to reduce the pressure in said other chamber whereby said valve member will move to a position to block communication between said input and output ports.

27. A control valve working section as claimed in claim 21 in which said control valve includes first and second motor ports; said valving element is effective in said first operating position to connect said first motor port to said inlet port, is effective in said second operating position to connect said second motor port to said inlet port, and is effective in said neutral position to isolate said inlet port from both said motor ports; and said logic means is effective to connect said other chamber to whichever motor port is connected to said inlet port and said logic means is also effective to connect said other chamber to said exhaust port whenever said valving element is in said neutral position.

28. A control valve working section as claimed in claim 27 in which said piston is movable from said first position to a bypass position remote from said first position by fluid pressure in said output port and said one chamber, and said piston is effective in said bypass position to open a communication path between said output port and said exhaust port whereby the fluid pressure in said output port is limited to the value required in said one chamber to actuate said piston to said bypass position.

32. A control valve working section as claimed in claim 23 in which said piston is movable from said first position to said second operating position and to a bypass position in which said piston opens a bypass path from said output port to a conduit communicating with said exhaust port.

33. A control valve having an inlet port, a motor port and a movable valve means intersecting said ports; a differential pressure sensitive valve having first and second ports, and a movable valve member having first and second pressure-responsive areas; said movable valve member defining a variable restriction flow path between said first and second ports, said first port being connected to a source of fluid pressure and said second port being connected to said inlet port of said control valve and said first pressure-responsive area; means connecting the motor port of said control valve to said second fluid-responsive area to control the pressure applied thereto and bias means associated with said second fluid-responsive area whereby said movable member moves to block the flow between said first and second ports when said control valve blocks communication between said inlet port and said motor port, whereby said inlet port of said control valve is isolated from said source of fluid pressure.