JPH0232483B2 - - Google Patents

Description

Claim 1: A valve assembly comprising: a housing 21 having an inlet chamber 22 connected to the pump 10, a supply chamber 23 connected to the fluid motor 15, and an evacuation device 12 for bypassing fluid; a control orifice device 14, 107, 108 disposed between the inlet chamber 23 and the fluid motor 15; and a first valve device 13a, 63a;
and the fluid restricting device 3 arranged between the supply chamber 23 and the supply chamber 23.
1 , 32 and is movable in response to actuation of a pilot valve device 38 , 42 having first and second annular spaces 35 , 41 separated by a spool 38 from the inlet chamber 22 to the supply chamber 23 . to maintain a constant differential pressure at a preselected constant level between the first and second spaces 35, 41 of the pilot valve devices 38, 42 and control orifice devices 14, 107, 108. The first valve device 13a, 63a maintains a constant differential pressure before and after the device 4, and the second valve device 13b, 63b, 82 controls the movement of the first valve device 13a, 63a.
8, 55, 75, 84, 83, and the first valve device 13
Devices 48, 55, 7 for controlling the movements of a, 63a
5, 84, 83 are control orifice devices 14, 10
7, 108, while the pressure difference between the first and second annular spaces 35, 41 of the pilot valve devices 38, 42 remains constant at said constant predetermined level. a second valve device 13b, 63b, 82, which remains as a valve assembly.

2. The valve assembly according to claim 1, wherein the control orifice device 14, 107, 10
8 is a valve assembly having a variable area orifice device V;

3. The valve assembly according to claim 1, wherein the control orifice device 14, 107, 10
8 connects the fluid motor 15 to the supply chamber 23;
Also, a valve spool 10 operable for selective connection to the discharge devices 100, 101, 12.
A valve assembly having 3.

4. In the valve assembly according to claim 1, the second valve device 13b is a constant pressure reducing device 4.
8,53, an orifice device 20 located upstream of the constant pressure reducing device 48,53, and a flow orifice device 57 located downstream of the constant pressure reducing device 48,53. assembly.

5. In the valve assembly according to claim 1, the second valve device 63b is connected to the discharge device 7.
3, 74, 25, 12, and the constant flow rate control device 7.
a variable control orifice device 55, 68 disposed upstream of the valve assembly 5, 76, 78;

6. In the valve assembly according to claim 1, the second valve device 82 includes a fluid restricting device 83,
84; and an orifice device 93 located downstream of the fluid restriction devices 83, 84 and in communication with the evacuation device 12.

7. A valve assembly according to claim 1, wherein said second valve device 13b, 63b, 82 has a device 58 responsive to an external control signal 59.

8. A valve assembly according to claim 7, wherein said device 58 responsive to an external control signal 59 comprises a mechanical operating device 117.

9. A valve assembly according to claim 7, wherein said device 58 responsive to an external control signal 59 comprises a hydraulic actuator 120,121.

10. The valve assembly of claim 7, wherein the device 58 is responsive to an external control signal 59.
is a valve assembly having electromechanical operating devices 123 and 124;

11. The valve assembly of claim 7, wherein said device 127 responsive to external control signals 132, 133, 134 comprises a logic circuit device 131, an amplifier device 130 and an electromechanical device 129. assembly.

BACKGROUND OF THE INVENTION The present invention relates generally to load-responsive fluid control valves and to fluid power systems incorporating such valves and supplied by a constant or variable displacement pump. Such control valves have automatic load responsive controllers and can be used in multi-load systems where multiple loads are individually controlled by separate control valves under positive load conditions.

In a more specific aspect, the invention relates to a directional and flow control valve that is capable of controlling multiple loads automatically and in a proportional manner under positive load conditions.

In a still more specific aspect, the present invention relates to a pilot-operated load-responsive controller for a directional control valve;
The controller automatically holds the control difference between the pump discharge pressure and the load pressure signal constant at each control level while allowing for changes in the level of the control difference.

In a still more specific aspect, the present invention relates to a pilot-operated load-responsive controller for a directional control valve;
The controller is responsive to external control signals to enable controlled differential pressure changes between the valve inlet pressure and the load pressure.

Center-closed load responsive fluid control valves are highly desirable for many reasons. These fluid control valves enable load control with less power loss, thus increasing system efficiency, and when controlling one load at a time, independent of changes in the magnitude of the load.
Provides proportional characteristics of flow control. Typically, such valves have a load-responsive controller that automatically increases the pump discharge pressure to a level that is a fixed differential pressure above the pressure required to support the load. to be maintained. Variable orifices introduced between the pump and the load vary the flow rate delivered to the load, with each orifice area corresponding to a different flow level that remains constant regardless of changes in load size. There is. However, the application of such systems has been limited due to one fundamental system drawback.

Typically, in such systems, the load-responsive valve controller is capable of maintaining a constant differential pressure and therefore a constant flow characteristic when only one load is operating at a time. can. 2
When more than one load is controlled simultaneously, only the largest of these loads retains its flow control characteristics, and the operating speed of the smaller loads changes as the magnitude of the largest load changes. A fluid control valve for such a system is shown in US Pat. No. 3,488,953 to Haussler.

This drawback is reflected in my U.S. Patent No. 3,470,694 dated October 7, 1969, and in my U.
A partial solution may be provided by providing a proportional valve as also disclosed in US Pat. No. 3,455,210. However, while these valves are effective in proportionally controlling a large number of positive loads at once, they provide a constant pressure differential across each valve, and therefore a constant throttling loss, which reduces system efficiency. It will lower it.
Additionally, these valves require relatively high energy level control signals because they use unamplified load pressure signals to operate their controllers.

SUMMARY OF THE INVENTION Therefore, the main object of the present invention is to provide an improvement which makes it possible to change the level of the control difference between the valve inlet pressure and the load pressure while automatically keeping it constant at each control level. An object of the present invention is to provide a pilot-operated load-responsive directional control valve.

Another object of the present invention is to change the area of the orifice while keeping the differential pressure across the orifice between the valve controller and the fluid motor constant at a certain level, or to keep the area of the orifice constant. It is an object of the present invention to provide a pilot-operated load response controller for a directional control valve, which can control the system load by controlling the differential pressure acting before and after the orifice while maintaining the orifice.

Another object of the present invention is to provide a pilot operated load responsive controller for a directional control valve that allows controlled differential pressure changes across a metering orifice in response to an external control signal.

Another object of the invention is to control the system load by varying the area of the metering orifice of a load-responsive directional control valve while controlling the differential pressure acting across the metering orifice by an external control signal at a minimum force level. It is an object of the present invention to provide a pilot-operated load-responsive controller for a directional control valve that can be adjusted and controlled by the present invention.

Another object of the present invention is a load-responsive controller for a directional control valve that modifies a control signal provided to a pilot-operated valve controller to control differential pressure across an orifice of a load-responsive directional control valve. A load responsive controller is provided.

Another object of the invention is a load-responsive controller for a directional control valve, which modifies the control signal provided at a minimum energy level to an amplification stage of the valve controller to increase the difference across the orifice of the load-responsive directional control valve. It is an object of the present invention to provide a load responsive controller for controlling pressure.

Briefly stated, the above and other additional objects of the present invention are to throttle the fluid delivered by the pump in response to a single control input, namely a change in the area of the metering orifice, thereby adjusting the valve inlet pressure and the load pressure. control a constant differential pressure to a preselected level between or in response to modification of the pressure of other control inputs, i.e., control signals, throttle the fluid delivered from the pump to the amplification stage of the valve controller. A new load on a directional control valve that changes the level of the control difference between the valve inlet pressure and the load pressure while automatically keeping it constant at each control level by the valve controller receiving a low energy control signal of This is accomplished by providing a responsive controller. Thus, the load can be controlled in response to either input providing the same control performance, or the variable differential pressure control action can be superimposed on the control action that controls the load by varying the area of the metering orifice. It can be done. Therefore, this control system is very useful in applications where manual control inputs from an operator can be modified by electronic logic circuits or a microprocessor.

SUMMARY OF THE INVENTION Accordingly, the main object of the present invention is to provide an improvement which makes it possible to vary the level of the control difference between the valve inlet pressure and the load pressure while automatically maintaining it constant at each control level. An object of the present invention is to provide a pilot-operated load-responsive directional control valve.

Another object of the present invention is to maintain the differential pressure across the orifice between the valve controller and the fluid motor constant at a specific level while changing the area of the orifice, or while keeping the area of the orifice constant. It is an object of the present invention to provide a pilot-operated load response controller for a directional control valve capable of controlling a system load by controlling differential pressure.

Yet another object of the present invention is to provide a pilot operated load responsive controller for a directional control valve that allows controlled differential pressure changes across a metering orifice in response to an external control signal.

Still another object of the present invention is to control the system load by varying the area of the metering orifice of a load-responsive directional control valve while controlling the differential pressure acting across the metering orifice by an external control signal at a minimum force level. It is an object of the present invention to provide a pilot operated load responsive controller for a directional control valve that can be adjusted and controlled.

Yet another object of the present invention is to provide a load responsive controller for a directional control valve that modifies the control signal provided to the pilot operated valve controller to control the differential pressure across the orifice of the load responsive directional control valve. That's true.

Yet another object of the present invention is to control a load responsive directional control valve by modifying a control signal provided at a minimum energy level to an amplification stage of the valve controller to control the differential pressure across the orifice of the load responsive directional control valve. It is to provide a vessel.

Briefly stated, the foregoing and other objects and advantages of the present invention are such that the fluid delivered by the pump is throttled in response to a single control signal, i.e., a change in metering orifice area, to reduce valve inlet pressure and load pressure. to a preselected level, or throttle the fluid delivered by the pump in response to other control signals, i.e., modifications of the control signal pressure, between the valve inlet pressure and the load pressure. a directional control valve that varies the level of the control difference between the two while being automatically maintained constant at each control level by the valve controller receiving a low energy control signal to an amplification stage of the valve controller; This is accomplished by providing a novel load-responsive controller. In this way, the load can be controlled in response to either input providing the same control performance, or by superimposing a variable differential pressure control action on the control action that controls the load by varying the area of the metering orifice. be able to. Therefore, this control system is very useful in applications where manual control inputs from an operator can be modified by electronic logic or a microprocessor.

Other objects of the invention will become apparent upon reference to the preferred embodiments of the invention as illustrated in the accompanying drawings and described in the detailed description below.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of a load-responsive pilot-operated throttling controller for adjusting the level of control differential from some preselected level to a zero level, and shows a schematic diagram of the fluid motor and system pump. 2 is a schematic diagram of a load responsive pilot operated throttle controller for adjusting the level of control differential from some minimum preselected level to a maximum level; FIG. 3 is a schematic diagram illustrating an alternative embodiment of the load-responsive pilot-operated controller of FIG. 1, schematically illustrating a fluid motor and system pump; FIG. FIG. 4 is a schematic diagram illustrating yet another embodiment of the load-responsive pilot-operated controller of FIG. Figure 6 is a schematic diagram of a four-way load-responsive directional control valve using the controller of Figure 1, schematically showing the system pump and reservoir; FIG. 7 is a schematic diagram showing manual control input to the load responsive controller; FIG. 7 is a schematic diagram of fluid pressure control input to the load responsive controller of FIGS. 1 to 5;
The figures are schematic diagrams of the electrical fluid pressure control inputs to the load response controllers of figures 1 to 5;
10 is a schematic diagram of the electromechanical control inputs to the load responsive controller of FIGS. 5 through 5; FIG. 10 is a schematic diagram of the electromechanical inputs to the load responsive system of FIG. 4;

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, the fluid pressure system shown in FIG. 1 includes a fluid pump 10 having an output flow controller 11 and It is connected to reservoir 12. The output flow rate controller 11 regulates the amount of output from the pump 10 into the load response circuit, and the load response circuit has a total of 1
The differential pressure throttle controller 13 is arranged between the differential pressure throttle controller 13 and the fluid motor 15 that operates the load (W). The differential pressure level across the schematically illustrated variable orifice 14 is adjusted. pump 1
0 may be of the constant or variable capacitance type and may be responsive to external or internal control signals. If the pump 10 is of the constant displacement type, the output flow controller 11 in response to an external control signal bypasses a portion of the flow from the pump to the system sump 12 to the load responsive circuit in well-known manner. Adjust the delivery amount from the pump. A constant displacement type pump 10 may also respond to a maximum pressure regulation signal using conventional relief valves well known in the art.
If the pump 10 is of the variable displacement type and is capable of responding to an external control signal, the output flow controller 11 controls the amount delivered from the pump to the load responsive circuit by varying the pump displacement with a displacement change mechanism. , adjusted in a known manner. The variable displacement type pump 10 may also be responsive to a maximum pressure regulation signal, such control being in the form of a conventional pressure compensator as is well known in the art.

Discharge line 16 of pump 10 is connected to fluid motor 15 through a differential pressure throttle controller, generally indicated at 13, line 17, variable metering orifice 14, and line 18. The fluid motor 15 is connected to the conduit 1
8 and 19 are also connected to the differential pressure throttle controller 13.

A differential pressure throttle controller, generally designated 13, comprising a throttle section generally designated 13a and a signal modification section generally designated 13b, has a housing 21; It has an inlet chamber 22, an outlet chamber 23, a first control chamber 24 and a discharge chamber 25, all of which are communicated with each other by a hole 26 in which a throttle spool 27 is slidably guided. ing. Land 28 and 29
The throttle spool 27 with stop 30 is provided with a throttle groove 31 between the inlet chamber 22 and the outlet chamber 23, which throttle groove 31 terminates in a cut-off edge 32. One end of the throttle spool 27 projects into the first control chamber 24 , and the other end projects into the discharge chamber 25 and is biased by a control spring 33 . The first control chamber 24 is communicated with an annular space 35 by a passage 34 . The hole 36 communicates the annular space 35 with the port 36 and the second control chamber 37, and the pilot valve spool 3.
8 in the axial direction. A pilot valve spool 38 with a metering land 39 and a land 40 defining an annular space 41 communicates with the port 36 and projects into a second control chamber 37 where it is Pilot valve spool 38 is engaged by spring 42. Second control room 3
7 is connected to the fluid motor 15 via a conduit 19 and an orifice 20, and is connected to the port 4.
3 to a supply chamber 44, which is connected by a hole 45 to a third control chamber 46 and to a discharge chamber 47. The bore 45 slidably guides a control spool 48, which is provided with a land 49.
is provided with a throttle groove 50 and is located between the supply chamber 44 and the third control chamber 46, and the control spool 48 also has a land 51 separating the supply chamber 44 and the discharge chamber 47. and a flange 52. A control spool 48 is located inside the discharge chamber 47.
A spring 53 is arranged between the housing 21 and the housing 21 . A discharge chamber 47 connected to the discharge chamber 25 by a passage 54 and a third control chamber 46 are connected to the discharge chamber 25 through a hole 56.
a stem 55 guided within and provided with a metering groove 57;
are selectively communicated with each other through metering orifices formed by. Stem 55 is coupled to an actuator 58 that is responsive to an external control signal 59. The discharge chambers 47 and 25, which are connected by a passage 54, are also connected to the annular space 41 and the leakage orifice 61 by a passage 60.

Referring to FIG. 2, the same components as used in FIG. 1 are designated by the same reference numerals. 1st
The only differences between the illustrated load-responsive controller and the load-responsive controller of FIG.
The communication form of individual ports or chambers to 0. In the same way in both figures, the pump pressure is applied to the discharge line 16, the inlet chamber 22, the outlet chamber 23 and the line 1.
7 and the fluid motor 1 through the variable orifice 14.
5. However, in FIG. 2, line 17 is connected to port 36 of pilot valve spool 38 via line 19 and orifice 20. The second control chamber 37 controls the load pressure (Pw) of the fluid motor 15 via pipes 62 and 19.
is in direct communication with. Supply chamber 44 is connected to port 36 via port 43 and selectively communicated with a third control chamber 46 by control spool 48 .

Referring to FIG. 3, the same components as used in FIGS. 1 and 2 are designated by the same reference numerals. Some of the basic load response circuitry of FIG. 3 is the same as that of FIGS. 1 and 2, including some of the internal components of the differential pressure throttle controller, indicated generally at 63. The differential pressure restrictor controller 63 has the same restrictor portion 63 as the restrictor portion 13a in FIGS. 1 and 2.
a, the flow rate control valve part 63b, and the metering valve part 63
It consists of c. The second control room 37 is located at port 6
4 communicates with a first pressure chamber 65, and the first pressure chamber 65 is connected to a second pressure chamber 67 through a hole 66, which hole 66 is provided with a metering groove 68. The stem 55 is guided. Stem 55 is connected to an actuator 58 that is responsive to an external control signal 59. The load check valve 69 is connected to the fluid motor 1
5 and the outlet chamber 23. The second control chamber 37 connects to the third pressure chamber 7 via a port 70.
1, the third pressure chamber 71 is connected by a hole 72 to a discharge chamber 73, and the discharge chamber 73 is connected to the discharge chamber 25 through a passage 74. The hole 72 is a measuring pin 7 with a measuring groove 76.
5 in the axial direction. The metering pin 75 has a stop 77 and is biased toward the position shown by a spring 78 located within the discharge chamber 73.

Referring to FIG. 4, the same components as used in FIGS. 1, 2, and 3 are designated by the same reference numerals. Some of the components of the basic load response circuit of FIG. 4, including some of the internal components of the differential pressure throttle controller, generally designated 79, are shown in FIGS. 1, 2, and 4. It is the same as that in Figure 3. The second discharge chamber 37 is connected via a port 80 to a chamber 81 of a differential pressure valve, generally indicated at 82. Differential pressure valve 82 has a coil 83 held within a housing that guides a solenoid armature 84, generally indicated at 85. The armature 84 includes a conical surface 86 selectively engageable with a sealing edge 87 of an inlet port 88 and a discharge passageway 89.
The discharge passage 89 has a hole 90 for guiding a recoil pin 91.
It ends at . The coil 83 is connected to the outside of the housing 21 by a sealed connector 92, and is actuated by an external control signal of the sealed connector 92. The second discharge chamber 37 is connected to the discharge chamber 2 through a leakage orifice 93 and a passage 94.
5 and reservoir 12.

Referring to FIG. 5, the same components as used in FIGS. 1, 2, 3, and 4 are designated by the same reference numerals. The differential pressure throttle controller 13 of FIG. 1 is connected to a four-way valve assembly, generally designated 95 in FIG. variable metering orifice 14. The four-way valve assembly, indicated generally at 95, has a housing 96 that includes a supply chamber 97, a load chamber 98, and a load chamber 98 connected to each other by a bore 102 guiding a valve spool 103. and 99 and discharge chamber 10
0 and 101. The valve spool 103 has lands 104, 105 and 106, and the throttle groove 10.
7, 108, 109 and 110, and signal groove 111
and 112. Housing 96 also includes load sensing ports 113 and 114 that communicate with second control chamber 37 of differential pressure throttle controller 13 via conduit 115 and orifice 20 .

Referring to FIG. 6, the stem 55 of the actuator 58 of FIGS. 1-5 is biased toward the zero orifice position by a spring 116 and is directly operated by a lever 117 that provides an external signal 59. Ru.

Referring to FIG. 7, stem 55 of actuator 58 of FIGS. 1-5 is biased toward the zero orifice position by spring 118 and is operated directly by piston 119. Referring to FIG. Fluid pressure is generated by a pressure generator 120 operated by a lever 121.
is supplied to the piston 119 from

Referring to FIG. 8, stem 55 of actuator 58 of FIGS. 1-5 is biased toward the zero orifice position by spring 122 and is directly operated by solenoid 123.
is connected by a line to an input current controller 124, which is connected to the lever 12.
5 and is supplied with current from an electrical supply source 126.

Referring to FIG. 9, a stem 55 of the differential pressure controller, indicated generally at 127, is urged by a spring 128 toward a position in which the third control chamber 46 is isolated from the discharge chamber 47 by the stem 55. energized and controlled by solenoid 129. The electrical control signal amplified by amplifier 130 is transmitted from a logic circuit or microprocessor 131 receiving inputs 132, 133 and 134.

With reference to FIG. 10, control signals 136, 137
A logic circuit or microprocessor 135, supplied with 138 and 138, communicates an external control signal to the differential pressure valve 82 via an amplifier 139.

Referring to FIG. 1, differential pressure throttle controller 13 is located between pump 10 and fluid motor 15 to control fluid flow rate and pressure between the pump and the fluid motor. The differential pressure throttle controller 13 is the throttle part 1
3a and a signal amplification section 13b.
The throttle section 13a with the throttle spool 27 is connected from the inlet chamber 22, which is connected to the pump 10 by the discharge line 16, to the line 17 and the variable orifice 1.
The fluid flow rate to the outlet chamber 23 connected to the fluid motor 15 via the fluid motor 15 is throttled by the throttle groove 31 to automatically maintain a constant differential pressure across the variable orifice 14. This control action is performed as follows. That is, the pressure (P ₁ ) acting on the upstream side of the variable orifice 14 is the outlet chamber 23.
Fluid is conveyed through line 17 to port 36 and creates a force acting on the cross-sectional area of pilot valve spool 38 tending to move the pilot valve spool 38 upwardly, thereby causing annular space 35 and to the first control room 24 via the passage 34 (P ₁ )
pressure is thereby communicated with the first control chamber 2.
Increase the pressure level within 4. Variable orifice 14
The fluid at load pressure ( _Pw ), which is the pressure acting on the downstream side of A force is generated tending to move the pilot valve spool downwardly, thereby communicating reservoir pressure from the annular space 41 to the annular space 35 and passageway 34 and into the first control chamber 24, thereby causing the first The pressure level in the control chamber 24 of the control chamber 24 is reduced. This force due to the pressure in the second control chamber 37 is added to the biasing force of the spring 42 . The pressure level in the first control chamber 24 acting on the cross-sectional area of the throttle spool 27 is controlled by the control spring 33.
increases above a level equal to the preload of , the throttle spool 27 is moved from right to left in the direction of closing the flow area through the throttle groove 31, i.e. in the direction of increasing the throttle action of the throttle spool 27. A force is generated to try to do so. On the contrary, the first
When the pressure level in the control chamber 24 falls below a level equal to the preload of the control spring 33, the throttle groove 31
The throttle spool 27 is moved from left to right by the control spring 33 in a direction that increases the flow area through it, ie in a direction that reduces the throttling action of the throttle spool 27. Therefore, the first control room 2
By adjusting the pressure level in 4, the pilot valve spool 38 influences the throttling action of the throttle spool 27 and thus the inlet chamber 22 which is under pressure (P _p ) and the inlet chamber 22 which is under pressure (P ₁ ). The pressure drop between the outlet chamber 23 and the outlet chamber 23 is controlled. Assume that stem 55 is in the position shown in FIG. 1, isolating third control chamber 46 from discharge chamber 47, thus leaving signal modification portion 13b inactive. The pilot valve spool 38 under the (P ₁ ) and (P ₂ ) pressures and the biasing force of the spring 42 reaches the adjustment position in which the first control chamber 24 is compressed by the throttling action of the metering land 39.
The pressure within and therefore the throttling action of the throttle spool 27 is adjusted to increase the pump pressure (P _p ) by a constant differential pressure (ΔP) equal to the quotient of the biasing force of the spring 42 and the cross-sectional area of the pilot valve spool 38. Throttle down to a level where the (P _{1 ) pressure is higher than the (P 2 )} pressure. In this manner, pilot valve spool 38 receiving a low energy pressure signal acts as an amplification stage that uses energy drawn from pump 10 to control the position or throttling action of throttle spool 27. A leak orifice 61 communicating the first control chamber 24 with the reservoir 12 via the passageway 60 and the discharge chamber 25 is used in a known manner to increase the stability of the pilot valve spool 38. If the (P ₂ ) pressure is equal to the (P _w ) pressure, as is the case when the stem 55 is in the position shown in FIG. By squeezing the exit chamber 23
A constant pressure difference (ΔP) is automatically maintained between the variable orifice 14 and the second control chamber 37, and (ΔP _y ) becomes (ΔP), so that a constant pressure difference is maintained before and after the variable orifice 14. If the differential pressure acting across the orifice is constant, the flow rate through the orifice is proportional to the area of the orifice and independent of the pressure within the fluid motor. Therefore, by changing the area of the variable orifice,
The fluid flow rate to the fluid motor 15 and the speed of the load (W) can be controlled, and each specific area of the variable orifice 14 has a load (W) that is kept constant regardless of changes in the magnitude of the load (W). ) corresponds to a specific speed.

In the configuration of FIG. 1, the relationship between load pressure (P _w ) and signal pressure (P ₂ ) is controlled by a signal modification section and orifice 20, indicated generally at 13b. A stem 55 positioned by an actuator 58 in response to an external control signal 59 is positioned in a first position.
As shown in the figure, the metering orifice passing through the metering groove 57 is completely closed and the third
It is assumed that the control room 46 is isolated. The control spool 48 with its land 49 projecting into the third control chamber 46 generates a pressure in the third control chamber 46 corresponding to the preload of the spring 53 . When the stem 55 is displaced from side to side, the measuring groove 5
7 emerges from the hole 56 and forms an orifice area through which fluid flow occurs from the third control chamber 46 to the discharge chamber 47 . The control spool 48, which is biased by the spring 53, moves from right to left and the throttle groove 50 causes the supply chamber 44 to be moved from the right to the left.
It communicates with the control room 46 of. control spool 48
When the pressure in the third control chamber 46, acting on the cross-sectional area of is throttled to maintain the third control chamber 46 at a constant pressure corresponding to the preload of the spring 53. Metering groove 5 with respect to hole 56
7 is displaced, the third control chamber 46 and the discharge chamber 47
The area of the metering orifice between is made to vary. A control spool 48 connects the discharge chamber 47 and the third
Since a constant pressure difference is automatically maintained between the metering groove 57 and the control chamber 46, that is, before and after the metering groove 57, each specific area of the metering groove 57 is independent of the magnitude of the pressure inside the supply chamber 44. from the control chamber 46 to the discharge chamber 47 and from the supply chamber 44 to the third control chamber 46. Therefore, each specific position of the stem 55 in the area of the metering groove 57 is determined by the fixed orifice 20, independent of the magnitude of the load pressure (P _w ).
corresponds to a specific flow rate level through , and thus a specific pressure drop (ΔP _x ). As can be seen with reference to FIG. 1, P ₁ −P _w =ΔP _y , P ₁ −P ₂ = ΔP, which are kept constant by the constriction portion 13a, and P _w − P ₂ =ΔP _x . By substituting and eliminating (P ₁ ) and (P ₂ ) from these equations, ΔP _y =
The basic relationship ΔP−ΔP _x is obtained. Since (ΔP _x ) can be changed by the signal modification part 13b or can be maintained constant at an arbitrary level, it is also possible to change (ΔP _y ) acting before and after the variable orifice 14 at an arbitrary level. It can also be kept constant. Therefore, at any particular constant area condition of the variable orifice 14, the differential pressure (ΔP _y ) can be varied from maximum to zero in response to the control signal 59, and each particular level of (ΔP _y ) corresponds to the load pressure ( It is automatically controlled to be constant regardless of changes in P _w ). Therefore, for each specific area of the variable orifice 14, the differential pressure acting before and after the orifice 14 and the flow rate passing through the orifice 14 can be controlled from the maximum to the minimum by the signal modification part 13b, and each flow rate level is automatically controlled to be constant by the differential pressure controller 13 regardless of changes in the load pressure (P _w ). As is clear from considering the basic formula ΔP _y = ΔP − ΔP _x , when ΔP _x = 0, ΔP _y = ΔP,
If the differential pressure (ΔP) of the differential pressure throttle controller 13 is the maximum constant differential pressure, the system returns to the conventional load responsive system operating mode. When ΔP _x = ΔP,
(ΔP _y ) becomes zero, and the output pressure (P ₁ ) from the differential pressure throttle controller 13 becomes equal to the load pressure (P _w ),
The flow rate through variable orifice 14 becomes zero.
If (ΔP _x ) is greater than (ΔP), then the pressure (P ₁ )
becomes smaller than the load pressure (P _w ), and the load check valve 18a is seated.

In the load response system of FIG.
The area of the variable orifice 14 can be varied for each particular value of ₍ ΔP _y ) kept constant by 15 corresponds to a specific constant flow rate. Conversely, for each specific area of the variable orifice 14, the differential pressure (ΔP _y ) acting before and after the orifice 14 is controlled by the differential pressure throttle controller 13.
can _be varied by the signal modification part through the constriction _part 13a of are doing. Therefore, by either changing the area of the variable orifice 14 or changing the differential pressure (ΔP _y ),
The fluid flow rate into the fluid motor 15 can be varied, and each of these control methods provides the same control characteristics and control flow rates that are independent of the magnitude of the load pressure. Unique in that one control action can be superimposed on the other, for example, a command signal from the operator through the variable orifice 14 can be corrected by a signal 59 from the computing device acting through the signal modification part 13b. system can be provided.

Referring to FIG. 2, the signal modification portion 13b is the first
It is identical to the signal modification section 13b in the figure and operates in a similar manner by modifying the control signal conveyed to the aperture section 13a. The constricted portion 13a in FIG. 2 is the same as the constricted portion 13a in FIG. However, instead of modifying the load pressure (P _w ) control signal as shown in the system of FIG. 1, the signal modification portion 13b of FIG. The control signal from the upstream side is modified. In Figure 2,
The load pressure signal (P _w ) is transmitted directly from the fluid motor 15 to the second control chamber 37 of the throttle section 13a. In that case, as understood from Figure 2,
P ₁ −P _w = ΔP _y , P ₁ −P ₂ = ΔP _x , and P ₂ −P _w = ΔP, where (ΔP) is the fundamental system differential pressure as described above. , is maintained constant by the throttle portion 13a of the differential pressure throttle controller 13. By substituting and eliminating (P ₁ ) and (P ₂ ) from the above equation, the basic relationship ΔP _y =ΔP+ΔP _x is obtained. Since (ΔP _x ) can be changed or kept constant at an arbitrary level, it is also possible to change (ΔP _y ) acting before and after the variable orifice 14.
It can also be kept constant at an arbitrary level. As is clear from considering the basic formula ΔP _y = ΔP + ΔP _x , when ΔP _x = 0, ΔP _y = ΔP, and if the minimum constant differential pressure (ΔP) is equal to the differential pressure at the throttle portion 13a, the system returns to the conventional load-responsive system operating mode. When (ΔP _x ) is any value other than zero, the differential pressure (ΔP _y ) acting across the variable orifice 14 is increased above the level of the constant differential pressure (ΔP) in the throttle portion 13a. Therefore,
Whereas the load-responsive control configuration in Figure 1 controls (ΔP _y ) within the range between (ΔP) and zero,
The load response configuration in FIG. 2 is such that (ΔP _y )
is controlled.

Referring to FIG. 3, the load response system is identical to the load response system of FIG. 1 except for a flow control valve section 63b and a metering valve section 63c, which are When combined together, it corresponds to signal modification portion 13b of FIG. 1 and operates in a very similar manner. The constricted portion 63a in FIG. 3 is the same as the constricted portion 13a in FIG. Differential pressure throttle controller 6 in Fig. 3
3 operates in the same manner as the differential pressure throttle controller 13 of FIG. Differential pressure throttle controller 63
The flow control valve part 63b is provided with a bore 72 in the housing 21, which guides a metering pin 75, which is connected to the third control chamber 71.
pressure within the chamber, reservoir pressure within the discharge chamber 73, and spring 7.
The third control chamber 71 is connected to the second control chamber 37 through a port 64 . Metering pin 75 moves from left to right under pressure in third control chamber 71, with each particular pressure level corresponding to a particular position of metering pin 75 with respect to housing 21 and to a particular biasing force of spring 78. is also supported. Each particular position of the metering pin 75 with respect to the housing 21 corresponds to a particular flow area of the metering groove 76 which communicates the third control chamber 71 with the discharge chamber 73. The shape of the metering groove 76 and the characteristics of the biasing spring 78 result in a relatively constant flow rate from the third control chamber 71 to the discharge chamber 73 due to changes in the effective orifice area of the metering groove 76 with respect to the pressure in the third control chamber 71. has been selected to be provided. In order to obtain specific control characteristics of the load-responsive controller, the shape of the metering groove 76 is selected to be able to obtain any desired relationship between the flow rate from the third control chamber 71 and its pressure level. obtain. Assume that the flow control valve section 63b provides a constant flow rate from the third control chamber 71 and thus from the second control chamber 37, regardless of pressure level. The flow control portion 63b can then be replaced in a manner known in the art with conventional flow control valves well known in the art. A constant flow rate to the third control chamber 71 is supplied from the fluid motor 15 via the metering valve section 63c, the second control chamber 37 and the port 70. The metering valve section 63c, which is arranged upstream of the flow control valve section 63b, is provided with a bore 66 for guiding the stem 55, which stem 55 is provided with a metering groove 68. When metering groove 68 is displaced beyond bore 66, an orifice is formed whose effective area is controlled by stem 55 by actuator 58 in response to external control signal 59.
can be changed by positioning.
When the stem 55 is engaged with the hole 66, the flow area of the metering valve portion 63c is zero. Therefore,
In response to external control signal 59, metering valve portion 63c
The effective flow area through can be varied from zero to a selected maximum value. The flow rate through the metering valve section 63c is kept constant by the flow control valve 63b, and each specific flow area through the metering valve section 63c is fixed in a well-known manner, independent of changes in the load pressure (P _w ). Corresponds to a constant pressure drop (ΔP _x ). Therefore, the load pressure signal is transmitted to the second control chamber 37 of the throttle portion 63a.
Each value of the pressure drop (ΔP _x ) that can be modified within and kept constant by the flow control valve section 63b is a differential pressure (ΔP _y ) according to the basic relationship ΔP _y = ΔP − ΔP _x
corresponds to a specific value of . Therefore, the control characteristics of the load-responsive controller of FIG. 3 are the same as those described with reference to FIG. 1, and the differential pressure (ΔP _y ) is
9 can be varied between a maximum value equal to (ΔP) and zero and can be kept constant at each particular level.

In the manner described above, the shape of the metering groove 76 and the spring 7
The biasing force characteristics of 8 can be selected to obtain any desired relationship between the pressure in the third pressure chamber 71 and the fluid flow rate through the metering valve portion 63c. Assume that in response to a particular external control signal 59, a particular flow area is created through metering valve member 63c. In that case, a controlled increase in the flow rate through the metering valve section 63c with increasing load pressure causes the differential pressure (ΔP _x ) to increase proportionally and therefore the differential pressure (ΔP _y ) to decrease proportionally. Being forced to
This effectively reduces the gain of the load responsive controller as the load pressure decreases. Conversely, a controlled decrease in the flow rate through a particular orifice area of the metering valve section 63c as the load pressure increases causes the differential pressure (ΔP _x ) to decrease proportionally, so that the differential pressure (ΔP _y ) is increased proportionally, effectively increasing the gain of the load responsive controller with increasing load pressure. As is well known in the art, the stability of many fluid flow and pressure controllers decreases as system pressure increases. Therefore, the ability to adjust the system gain in relation to system pressure is of paramount importance. Flow control valve part 63
b, the rate of change of the differential pressure (ΔP _y ) with respect to the load pressure must not be constant, but can be varied in any desired manner.

Referring to FIG. 4, the load response system is similar to that of FIG. The throttle controller 79 of the differential pressure throttle controller of FIG. 4 is identical to the differential pressure throttle section 13a of FIG. However, although differential pressure valve 82 is different from signal modification portion 13b of FIG. 1, it serves the same function and provides the same performance. The differential pressure valve, generally indicated at 82, has a solenoid, indicated generally at 85, which includes a coil 83 fixed to the housing 21 and a coil 83 fixed to the housing 21.
Armature 84 slidably guided within 3
It consists of Armature 84 includes a conical surface 86 that cooperates with a sealing edge 87 to regulate the differential pressure (ΔP _x ) between inlet port 88 and port 80 . A relatively weak spring, not numbered, may be placed between the armature 84 and the housing 21 to permit backflow from port 80 to inlet port 88 when coil 83 is in the de-energized state. can. This feature is important when a shuttle valve logic system is used to convey control signals instead of a check valve system. A sealed connector 92 within housing 21, as is well known in the art, connects coil 83 to an external terminal.
An external signal 59 can be supplied to the external terminal. A solenoid is an electro-mechanical device that uses electromagnetic principles to generate an output force from an electrical input signal. The force exerted on solenoid armature 84 is a function of input current. When current is supplied to coil 83, each particular current level corresponds to a particular force level delivered to the armature. Therefore, the contact force between the conical surface 86 of the armature 84 and the sealing edge 87 of the housing 21 is varied and controlled by the input current. This arrangement therefore allows the armature 8 to
an external signal 59 of input current proportional to the force exerted on the solenoid 85 and therefore supplied to the solenoid 85
input port 88 and second control room 37 in proportion to
It corresponds to a type of differential pressure throttle valve that automatically changes the differential pressure (ΔP _x ) between The pressures acting on the armature 84 within the housing 21 are completely balanced except for the pressure due to the differential pressure (ΔP _x ) acting on the surrounding area of the sealing edge 87 . The force due to this differential pressure is partially balanced by the reaction force generated in the cross-sectional area of the reaction pin 91, which
A hole 90 communicates with the inlet port 88 through 9.
Guided inside. The cross-sectional area of the recoil pin 91 must necessarily be smaller than the area surrounded by the sealing edge 87, so that the differential pressure (ΔP _x )
is adapted to oppose the force generated by solenoid 85. The recoil pin 91 allows the use of a larger inlet port 88 and also allows for a very significant reduction in the size of the solenoid 85 while allowing the solenoid 85 to operate within a higher range of (ΔP _x ). make it possible. The second control chamber 37 is connected to the system sump by a leak orifice 93 and passageway 94.

Referring to FIG. 5, the load response system is the same as that shown in FIG. 1, and the same differential pressure restrictor controller is used, but the variable orifice 14 of FIG. The whole has been replaced with a load-responsive four-way type directional control valve shown at 95. The performance of the control embodiments of FIGS. 1 and 5 is the same, the only difference being the construction of the variable orifice. Differential pressure throttle controller and in particular second load chamber 3
7 is connected to load sensing ports 113 and 114 of a four-way valve 95 via an orifice 20 and a conduit 115. With the valve spool 103 in the neutral position as shown in FIG. Effectively isolated from load pressure. Under such conditions, in a well-known manner,
The differential pressure throttle controller 13 controls the (ΔP) of the throttle portion 13a.
automatically maintains a minimum pressure in the supply chamber 97 equal to . When the valve spool 103 is displaced from its neutral position in either direction, the load chamber 99 or 98 is initially brought into communication with the load pressure sensing port 113 or 114 by the signal groove 111 or 112, while the load chamber 99 or 98 98 is still isolated from supply chamber 91 and discharge chambers 100 and 101 by valve spool 103. In that case, the load pressure signal is communicated via the load pressure sensing port 113 or 114, the line 115 and the orifice 20 to the second control chamber 37 so that the metering orifice
9 or 98, the differential pressure throttle controller 13
makes it possible to react. Further displacement of the valve spool 103 in either direction creates a metering orifice through the metering groove 107 or 108 between one of the load chambers and the supply chamber 97, while the other load chamber is connected to the metering groove 109 or 110. is connected to a discharge chamber, which is connected to the system sump. The metering orifice can be varied by displacement of the valve spool 103, each position of which is uniquely positioned within one of the load chambers, independent of the magnitude of the load controlled by the four-way valve assembly 95. It corresponds to the flow rate. As described above with reference to FIG. 1, this control action can be superimposed on the control action of the signal modification portion 13b. With the valve spool 103 displaced to an arbitrary specific position corresponding to an arbitrary specific area of the metering orifice, the differential pressure throttle controller 13 with the signal modification portion 13b proportionally adjusts the flow into the load chamber. Each value of the differential pressure (ΔP _y ) can be controlled at a constant level corresponding to a particular flow level into the load chamber, independent of the magnitude of the load controlled by the four-way valve assembly 95, at the throttle portion 13a. automatically maintained by

Referring to FIG. 6, stem 55 of actuator 58 of FIGS. 1-5 is biased by spring 118 toward the zero orifice position and lever 1
17, which lever 117 provides an external signal 59 in the form of a manual input.

Referring to FIG. 7, stem 55 of actuator 58 of FIGS. 1-5 is biased by spring 118 toward the zero orifice position and is operated directly by piston 119. Referring to FIG. Fluid pressure is supplied to the piston 119 in a known manner from a pressure generator 120, which is operated by a lever 121. The arrangement of FIG. 7 thus provides an external signal 59 in the form of a fluid pressure signal.

Referring to FIG. 8, the stem 55 of the actuator 58 of FIGS. 1-5 is biased by a spring 122 toward the zero orifice position and is directly operated in a well-known manner by a solenoid 123. Solenoid 123 is connected by line 125 to input current controller 124, which input current controller 1
24 is operated by a lever 125 and is supplied with power from a power source 126. Therefore, the eighth
In the configuration shown in the figure, in proportion to the amount of displacement of the lever 125,
An external signal 59 in the form of a current is provided.

Referring to FIG. 9, the stem 55 of the differential pressure controller 127 is connected to the third control chamber 46 by the stem 55.
the spring 1 towards a position where it is isolated from the discharge chamber 47.
28. The stem 55 is perfectly pressure balanced and can be operated through very small strokes, and the stem 55 is designed to operate at low pressure and low flow rates such that the effects of flow forces are negligible. control. In either case, if the area of the metering groove 57 is chosen so that it provides a linear function with respect to the displacement of the stem 55 and a constant pressure is maintained in front of the orifice, the flow The force is also linear and is applied to the spring force to cause the combined spring constant of the spring to change slightly. Stem 55 is linearly connected to solenoid 129.
A solenoid is an electromechanical device that uses electromagnetic principles to generate an output force from an electrical input signal. The position of the solenoid armature when spring biased is a function of the input current. When current is applied to the coil, the force created thereby causes the armature to move from its de-energized position to its energized position. When spring biased, for each specific current level there is a corresponding specific position that the solenoid reaches. When the current is varied from zero to the maximum rating, depending on the specific current level at any instant,
The armature moves in one direction from a fully retracted position to a fully extended position in the manner envisioned. Since the force produced by solenoid 129 is very small, the input current controlled by logic circuitry or microprocessor 131 is also very small. Microprocessor 131 is responsive to various types of signal converters to directly control system loads in terms of speed, force, and position, or microprocessor 131 can superimpose its actions on operator control functions. ,
in the minimum amount of time, with the minimum amount of energy, within the maximum capacity of the structure of the machine, and within the power range of the machine,
Able to perform required tasks.

Referring to FIG. 10, a logic circuit or microprocessor 13 similar to that described in FIG.
The control signal from 5 is conveyed directly via amplifier 139 to differential pressure controller 82, which uses a solenoid and throttle valve combination in the manner described above with reference to FIG. Adjust differential pressure in response to input current.

Although the preferred embodiments of the invention have been illustrated and described in detail, the invention is not limited to the precise form and construction shown, and is not intended to be limited to the precise form and construction shown, as can be done by one of ordinary skill in the art once the invention is fully understood. It will be appreciated that various modifications and alterations may be made without departing from the scope of the invention as set forth in the claims.