EP0150308A2 - Appareil pour contrôler un courant de fluide - Google Patents

Appareil pour contrôler un courant de fluide Download PDF

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Publication number
EP0150308A2
EP0150308A2 EP84114156A EP84114156A EP0150308A2 EP 0150308 A2 EP0150308 A2 EP 0150308A2 EP 84114156 A EP84114156 A EP 84114156A EP 84114156 A EP84114156 A EP 84114156A EP 0150308 A2 EP0150308 A2 EP 0150308A2
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EP
European Patent Office
Prior art keywords
valve
fluid
load sense
pilot
pressure
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP84114156A
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German (de)
English (en)
Other versions
EP0150308A3 (fr
Inventor
Allan R. Steinkuhl
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Northrop Grumman Space and Mission Systems Corp
Original Assignee
TRW Inc
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Filing date
Publication date
Application filed by TRW Inc filed Critical TRW Inc
Publication of EP0150308A2 publication Critical patent/EP0150308A2/fr
Publication of EP0150308A3 publication Critical patent/EP0150308A3/fr
Withdrawn legal-status Critical Current

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B13/00—Details of servomotor systems ; Valves for servomotor systems
    • F15B13/02—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors
    • F15B13/04—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with a single servomotor
    • F15B13/042—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with a single servomotor operated by fluid pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/16—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors
    • F15B11/161—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors with sensing of servomotor demand or load
    • F15B11/165—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors with sensing of servomotor demand or load for adjusting the pump output or bypass in response to demand
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B13/00—Details of servomotor systems ; Valves for servomotor systems
    • F15B13/02—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors
    • F15B13/04—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with a single servomotor
    • F15B13/0416—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with a single servomotor with means or adapted for load sensing
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/205—Systems with pumps
    • F15B2211/2053—Type of pump
    • F15B2211/20538—Type of pump constant capacity
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/305—Directional control characterised by the type of valves
    • F15B2211/30525—Directional control valves, e.g. 4/3-directional control valve
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/32—Directional control characterised by the type of actuation
    • F15B2211/329—Directional control characterised by the type of actuation actuated by fluid pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/50—Pressure control
    • F15B2211/505—Pressure control characterised by the type of pressure control means
    • F15B2211/50509—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means
    • F15B2211/50536—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means using unloading valves controlling the supply pressure by diverting fluid to the return line
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/50—Pressure control
    • F15B2211/57—Control of a differential pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/605—Load sensing circuits
    • F15B2211/6051—Load sensing circuits having valve means between output member and the load sensing circuit
    • F15B2211/6052—Load sensing circuits having valve means between output member and the load sensing circuit using check valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/635—Circuits providing pilot pressure to pilot pressure-controlled fluid circuit elements
    • F15B2211/6355—Circuits providing pilot pressure to pilot pressure-controlled fluid circuit elements having valve means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/705—Output members, e.g. hydraulic motors or cylinders or control therefor characterised by the type of output members or actuators
    • F15B2211/7051—Linear output members
    • F15B2211/7053—Double-acting output members
    • F15B2211/7054—Having equal piston areas
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/705—Output members, e.g. hydraulic motors or cylinders or control therefor characterised by the type of output members or actuators
    • F15B2211/7058—Rotary output members
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/71—Multiple output members, e.g. multiple hydraulic motors or cylinders

Definitions

  • the present invention relates to apparatus for directing fluid from a source to a hydraulic motor. It relates particularly to an apparatus comprising a plurality of valves that are selectively operable to direct fluid from the source to respective hydraulic motors which operate under different load conditions.
  • fluid from a single source may be used to operate such devices as (i) a reel motor that normally operates under a relatively low load (e.g. about 500 psi), and (ii) a header motor which normally operates under a relatively high load (e.g. about 2,000 psi).
  • the fluid from the source is communicated with a plurality of control valves that are in a parallel fluid circuit. Each control valve is selectively operable to direct fluid from the source to a respective hydraulic motor.
  • such a system is made "load sensitive", i.e., the load pressures on the motors are sensed, and fluid delivered from the source is controlled in accordance with those loads.
  • load sensitive i.e., the load pressures on the motors are sensed, and fluid delivered from the source is controlled in accordance with those loads.
  • fluid delivered from the source is reduced to a minimum standby level.
  • the highest load pressure is sensed, and the fluid delivered from the source is increased to a level where it exceeds that highest load pressure by a predetermined amount.
  • a fluid logic circuit senses the load pressures on each of the motors in the system, and establishes a load sense pressure signal that corresponds to the highest load pressure on a motor in the system.
  • the load sense pressure signal is communicated to a means that controls the fluid delivered from the source, and that means operates to maintain fluid delivered from the source at predetermined fluid pressure differential above the load sense pressure signal.
  • the source will deliver adequate fluid to handle the highest load pressure in the system.
  • the load sense pressure signal may change as different motors are operated, and as the loads on the different motors change.
  • the load sense pressure signal changes, the fluid delivered from the source will change, in order to maintain the pressure of the fluid delivered from the source at the predetermined pressure differential above the highest load pressure in the system.
  • U.S. Patent 4,126,293 A known type of control valve means that can be used in the foregoing type of system is shown in U.S. Patent 4,126,293.
  • a valve element is spring biased to a neutral position in which no flow is directed to the motor associated with that valve.
  • the valve can move away from the neutral position when a differential pressure is applied to the valve that overcomes the spring bias.
  • the differential pressure is provided by directing pilot fluid from the source to one side of the valve element, while communicating the other side of the valve element with the reservoir. This creates a differential pressure across the valve element, and causes the valve element to shift away from its neutral position.
  • As the valve shifts away from its neutral position it establishes, and then gradually increases, a variable orifice that directs fluid from the source to its respective motor.
  • the amount of the differential pressure across a valve determines the extent to which the valve moves away from its neutral position. As the differential pressure across a valve element changes, the position of the valve element, and the size of the variable orifice established by the valve element, changes accordingly. When the differential pressure across the valve element reaches a steady-state condition, the size of the variable orifice established by the valve element remains essentially constant.
  • a load sense system in which a plurality of pilot fluid actuated valves are provided (e.g., valves such as in U.S. Patent 4,126,293) it is difficult to maintain a steady-state, predetermined differential pressure across a given valve element as different motors are operated, and as the loads applied to the different motors change. Specifically, as the loads on the motors change, the load sense pressure signal, and the fluid pressure delivered from the source will change. The amount of fluid delivered from the source will tend to fluctuate as the loads on the motor change, because the variable orifices established by the valve elements are essentially fixed.
  • the pilot fluid that is used to operate the valves utilizes fluid from the source, fluctuations in the fluid delivered from the source will cause the pilot fluid pressure applied to one side of a valve element to fluctuate. Without a corresponding change in fluid pressure on the other side of the valve, the differential pressure across the valve element would tend to fluctuate, and it would be difficult for a steady-state differential pressure to be maintained across any of the valves in the system.
  • an additional pump is usually provided for directing a compensating fluid pressure to the side of a valve opposite to the side the pilot fluid pressure is applied to.
  • a special compensating valve can be provided for compensating the pilot fluid pressure directed to the one side of the valve element.
  • the compensating fluid pressure compensates for fluid pressure variations introduced into the pilot conduit by changes in the source flow due to changing load conditions.
  • the compensating fluid pressure on a valve must be controlled so that it changes when the load sense pressure signal in the system changes, so that fluctuations in the source pressure, due to changing load conditions, do not affect the net differential pressure on the valve.
  • the present invention provides a system in which constant, predetermined differential pressures can be maintained across each Valve in the system, even where the loads on the motors in the system are fluctuating, and without the need for an additional pump or a special compensating valve to compensate for those load fluctuations.
  • a load sense pressure signal representing the highest load on a motor in the system, is continuously communicated directly to fluid chambers formed on both sides of each valve in the system.
  • each valve should remain in the position established by its respective pilot fluid differential pressure.
  • Fig. 1 shows a demand system in which flow from a fixed displacement pump 10 is utilized to operate a pair of hydraulic motors 12, 14, respectively.
  • Flow from the pump 10 is controlled by a demand (or unloading) valve 16 and is directed to a circuit comprising a pair of control valves 18, 20 that are in parallel with each other.
  • the control valve 18, when actuated, directs fluid to the fluid motor 12.
  • the control valve 20, when actuated, directs fluid to the fluid motor 14.
  • the demand valve 16 operates to bypass excess fluid to a reservoir 22 when the fluid delivered from the pump 10 exceeds the highest load pressure in the system by a predetermined amount.
  • the motors 12, 14 can be of various types and can operate under considerably different fluid pressures.
  • the motor 12 could be a double-acting motor that raises and lowers the header in a farm combine, and may operate under relatively high pressures in the range of 2000 psi.
  • the motor 14 might be a rotary motor for driving a reel, and might operate under a relatively low pressure, on the order of 500 psi.
  • Fluid from the pump 10 is communicated, via a conduit 24, with the inlet 26 of the demand valve 16.
  • the fluid is further communicated, via a delivery conduit 28, and a pair of parallel conduits 30, 32, to respective inlets 34, 36 of the control valves 18, 20.
  • Each of the control valves 18, 20 is biased to a neutral position in which the fluid at its inlet is blocked.
  • a control valve can be moved away from its neutral position, to establish a variable orifice through which fluid is directed to the motor associated with the control valve.
  • the control valve 18 is in its neutral position; hence the fluid at its inlet 34 is blocked.
  • the control valve 20 has been moved away from its neutral position, and is directing fluid to its associated motor 14.
  • the control valves 18, 20 are identical to each other.
  • the control valve 18 shown is shown in detail in Figs. 3-8.
  • the control valve includes a housing 40 defining a longitudinally extending fluid chamber 42 therein.
  • the valve chamber 42 defines several annular cavities, including a central cavity 42d, a pair of load sense cavities 42a, a pair of motor outlet cavities 42b, and a pair of return cavities 42c.
  • a valve spool 44 can move axially in the chamber 42, to control the flow of fluid.
  • the valve's inlet port 34 is formed in the housing 40.
  • the inlet port 34 communicates, through a passage 35, with the central cavity 42d forming part of the valve chamber 42.
  • a pair of working ports 46, 48 are also formed in the housing 40.
  • the working ports 46, 48 communicate with respective motor outlet cavities 42b that form part of the valve chamber 42.
  • a return port 50 is also formed in the housing 40 and communicates with a pair of annular return cavities 42c forming part of the valve chamber 42.
  • a first load sense port 80a (Figs. 3, 5) is formed in the housing, and communicates with a load sense conduit 72 in the system, as described more fully hereinafter.
  • a pair of springs 54 act on the opposite sides of the valve spool 44.
  • the springs 54 apply equal and opposite forces to the valve spool 44, and bias the valve spool 44 toward a neutral position.
  • a pair of lands 56, 58 on the valve spool 44 cooperate with respective land 60, 61 on the housing 40 to block flow through the central cavity 42d into the load sense cavities 42a.
  • a pair of lands 63, 65 on the valve spool 44 cooperate with housing 40 to block flow from load sense cavities 42a into motor outlet cavities 42b.
  • a pilot fluid pressure is communicated to one of a pair of pilot fluid pressure chambers 62, 64 on the opposite sides of the valve spool 44.
  • a first pilot fluid passage means 66 (shown substantially in Fig. 1) is formed in the housing 40 and extends from the inlet 34 to one pilot fluid pressure chamber 62.
  • a first solenoid operated restrictor 72 blocks flow in the first pilot fluid passage means 66.
  • a second pilot fluid passage means 68 is formed in the housing 40, and extends from the inlet 34 to the other pilot fluid pressure chamber 64.
  • a second solenoid operated restrictor 74 blocks flow in the second pilot fluid passage means 68.
  • the first pilot fluid passage means 66 includes a series of passages 66a, 66b, 66c, 66d and 66e formed in the housing 40.
  • the second fluid passage means includes a series of passages 68a, 68b, 68c, 68d and 68e formed in the housing 40.
  • the first solenoid operated restrictor 72 can establish and control communication between the inlet 34 and the pilot fluid pressure chamber 62 and the second solenoid operated restrictor 74 can establish and control communication between the inlet 34 and the pilot fluid pressure chamber 64.
  • Each of the solenoid operated restrictors 72, 74 is constructed according to the principles of U.S. Patent 4,126,293. It includes a solenoid actuated element (e.g., 74a in Fig. 3) that controls fluid in a respective pilot passage means 66 or 68. Specifically, each of the pilot passages 66c and 68c defines an orifice.
  • the solenoid actuated element (e.g., 74a) associated with a pilot passage means can either block the orifice (66c, 68c) in that passage or establish a flow area (i.e., size) for that orifice.
  • a solenoid operated restrictor When a solenoid operated restrictor is actuated, it establishes a level of flow through a respective one of the orifices (66c or 68c), to communicate pilot fluid to the associated pilot fluid pressure chamber on one side of the valve.
  • By varying the actuating force of the restrictor it is possible to vary the flow area (size) of the associated orifice; thereby varying the pilot fluid pressure applied to one side of the valve spool 44.
  • a solenoid operated restrictor When a solenoid operated restrictor is deactivated, it blocks flow through its associated orifice, thus blocking communication between its respective pilot fluid pressure chamber and the inlet 34. Therefore, to operate a valve, one of the solenoid operated restrictors 72, 74 is actuated, to communicate pilot fluid to the pilot fluid pressure chamber on one side of the valve, while the other solenoid operated restrictor is not activated, thus blocking the other pilot fluid pressure chamber from the inlet.
  • a load sense pressure circuit provides a pressure signal which is utilized to regulate the amount of fluid delivered from the source.
  • a fluid logic circuit communicates the working port of each control valve through a one way check valve 70, with a load sense conduit 72.
  • the one way check valves 70 allow only the highest load pressure signal to be communicated to the load sense conduit 72.
  • the load pressure at its working port if higher than the pressure in conduit 72, communicates its pressure to the conduit 72. That signal is, in turn, directed to the demand valve 16 and is used to regulate the amount of fluid delivered from the source.
  • the pressure in conduit 72 communicates with a spring chamber 100 on one side of the demand valve. That pressure, along with a spring 102, biases the demand valve element 104 toward the position shown in Fig. 2.
  • the pressure from the pump is communicated with the opposite side of the demand valve element 104.
  • the pressure differential across the demand valve element 104 can shift the demand valve element 104 to a position where it begins directing excess fluid to the reservoir 22.
  • a predetermined pressure differential (determined basically by the force of spring 102) is reached, excess fluid is directed to the reservoir 22.
  • the predetermined pressure differential is not reached, all fluid is directed to the system.
  • the highest load sense signal in the system is continuously communicated with the pilot fluid pressure chambers 62, 64 on the opposite sides of each control valve in the system, when the control valves are in neutral, and also when they are operating.
  • This principle is shown schematically in Fig. 1.
  • the load sense conduit 72 and the spring chamber 100 of the demand valve see the highest load pressure in the system.
  • Conduit means respresented schematically in Fig. 1 at 85, 87, 89, 91, 93 and 95, communicate the load sense pressure from the spring chamber 100 of the demand valve with the pilot passages 66e, 68e, thus communicating load sense pressure with the pilot fluid pressure chambers 62, 64.
  • a change in the load sense pressure in conduit 72 and spring chamber 100 is communicated to both sides of each control valve in the system.
  • a load sense passage 90 is disposed in the housing of each control valve.
  • One end of :he load sense passage 90 communicates with'one of the load sense fluid cavities 42b.
  • both of the load sense Eluid cavities 42b are communicated with each other, by neans of diagonal bores 98 formed in the valve spool 44. rhus, regardless of which way the valve spool 44 shifts, the fluid pressure directed to the associated motor is communicated with the load sense pressure passage 90.
  • the other side of the load sense pressure passage 90 of each valve is connected, through a one way check valve 70, to the first load sense stack port 80a formed in the housing of the valve.
  • the load sense stack ports 80a of each of the control valves in the system are connected to the load sense conduit 72.
  • the one way check valve 70 for each valve is disposed in the load sense passage 90 in the valve.
  • One side of the check valve 70 sees the pressure of load sense conduit 72 which is communicated with the first load sense port 80a of each valve. That pressure, along with the force of a spring 96, biases the check valve 70 to a position in which it closes communication between the outlet fluid pressure cavities 42a and the first load sense stack port 80a.
  • each valve has another load sense stack port 80b (Figs. 7, 8).
  • the conduit means 87, 91, 93 and 95, that communicate with load sense pressure in the spring cavity 100, are disposed within the valve housings, and the load sense stack port 80b forms a part of that conduit means.
  • the load sense stack ports 80a, 80b for each valve constitute a load sense port means for the valve.
  • the bias of the springs 54 provide the bias forces that must be overcome (i) to initially actuate a valve, or (ii) to move a valve further from its neutral position.
  • the load sense pressure feeds the chambers at both sides of each valve, and therefore provides no net fluid biasing force on the valves.
  • the solenoid operated restrictor associated with one side of a valve When the solenoid operated restrictor associated with one side of a valve is actuated, it establishes a variable orifice 66c, 68c (Fig. 1) in the pilot fluid passage between the inlet 34 and its associated pilot fluid chamber 62, 64. Also, the pilot fluid chambers 62, 64 are communicated (through orifice means represented at 78a, 78b) with the load sense pressure in the spring chamber 100 of the demand valve (see Fig. 1). Specifically, the conduit means shown schematically at 85, 87, 89, 91, 93 and 95 in Fig. 1 is in fact provided partly inside the valves and partly outside the valves. It communicates load sense pressure from the spring cavity 100 of the demand valve with a second load sense port 80b (Fig. 7) formed in each valve. Within each valve, that load sense pressure is communicated through orifice means 78a, 78b with each of the pilot fluid chambers 62, 64 in the manner schematically set forth in the Figure
  • a solenoid operated restrictor when actuated a pilot flow is established through the variable orifice (66c or 68c) and to the load sense conduit 72 via the spring chamber 100.
  • the flow area established by the solenoid determines the pilot pressure differential that exists across a particular valve spool 44. That pressure differential operates to shift the valve spool in one direction to establish a fluid flow to its associated motor.
  • the valve element 20 has been shifted to an operating position where it is directing fluid to its respective motor 14.
  • the pilot fluid pressure differential established across the valve spool 44 can be changed by changing the flow area of the variable orifice (66c or 68c) established by the solenoid. Changing the fluid pressure differential is desirable when it is desired to change the amount of flow being directed by a valve to its associated motor. However, once a predetermined pilot fluid pressure differential across a valve is established, that predetermined differential should remain substantially constant, even if there are pressure fluctuations throughout the system due to changing loads on a motor, or due to the operation of different motors requiring different fluid pressures. Theinvention maintains the pressure differentials constant, by communicating the load sense conduit 72 with the pressure chambers 62, 64 on both sides of each of the valves in the system. Also, each valve has a manual override means 99 (Fig. 8) for manually controlling pilot fluid pressure directed to the pressure chambers.
  • variable orifices 66c, 68c

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Fluid-Pressure Circuits (AREA)
EP84114156A 1984-01-30 1984-11-23 Appareil pour contrôler un courant de fluide Withdrawn EP0150308A3 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US57499184A 1984-01-30 1984-01-30
US574991 1984-01-30

Publications (2)

Publication Number Publication Date
EP0150308A2 true EP0150308A2 (fr) 1985-08-07
EP0150308A3 EP0150308A3 (fr) 1986-10-01

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP84114156A Withdrawn EP0150308A3 (fr) 1984-01-30 1984-11-23 Appareil pour contrôler un courant de fluide

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EP (1) EP0150308A3 (fr)
JP (1) JPS60159404A (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0326150A1 (fr) * 1988-01-27 1989-08-02 Hitachi Construction Machinery Co., Ltd. Système de commande sensible à la charge pour un circuit hydraulique
CN104196801A (zh) * 2014-09-05 2014-12-10 酒泉奥凯种子机械股份有限公司 一种液压马达调速反馈控制阀

Citations (6)

* Cited by examiner, † Cited by third party
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US3742980A (en) * 1972-04-03 1973-07-03 Sanders Associates Inc Hydraulic control system
US3780623A (en) * 1970-07-15 1973-12-25 H Hohlein Valve unit for controlling double acting fluid operating cylinders
US4126293A (en) * 1976-07-16 1978-11-21 Control Concepts, Inc. Feathering valve assembly
GB2044961A (en) * 1979-03-23 1980-10-22 Dowty Hydraulics Units Ltd Servo valve
EP0041247A2 (fr) * 1980-06-03 1981-12-09 Backé, Wolfgang, Prof. Dr.-Ing. Dispositif asservi pour réglage de débit indépendant de la charge
CH636931A5 (en) * 1979-04-12 1983-06-30 Aroflex Ag Proportional valve

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3780623A (en) * 1970-07-15 1973-12-25 H Hohlein Valve unit for controlling double acting fluid operating cylinders
US3742980A (en) * 1972-04-03 1973-07-03 Sanders Associates Inc Hydraulic control system
US4126293A (en) * 1976-07-16 1978-11-21 Control Concepts, Inc. Feathering valve assembly
GB2044961A (en) * 1979-03-23 1980-10-22 Dowty Hydraulics Units Ltd Servo valve
CH636931A5 (en) * 1979-04-12 1983-06-30 Aroflex Ag Proportional valve
EP0041247A2 (fr) * 1980-06-03 1981-12-09 Backé, Wolfgang, Prof. Dr.-Ing. Dispositif asservi pour réglage de débit indépendant de la charge

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0326150A1 (fr) * 1988-01-27 1989-08-02 Hitachi Construction Machinery Co., Ltd. Système de commande sensible à la charge pour un circuit hydraulique
US4967557A (en) * 1988-01-27 1990-11-06 Hitachi Construction Machinery Co., Ltd. Control system for load-sensing hydraulic drive circuit
CN104196801A (zh) * 2014-09-05 2014-12-10 酒泉奥凯种子机械股份有限公司 一种液压马达调速反馈控制阀

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EP0150308A3 (fr) 1986-10-01
JPS60159404A (ja) 1985-08-20

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