US3631890A - Flow extending bypass valve - Google Patents

Flow extending bypass valve Download PDF

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Publication number
US3631890A
US3631890A US3631890DA US3631890A US 3631890 A US3631890 A US 3631890A US 3631890D A US3631890D A US 3631890DA US 3631890 A US3631890 A US 3631890A
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fluid
port
pressure
bypass valve
bypass
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Kenneth G Mcmillen
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Borg Warner Corp
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Borg Warner Corp
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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
    • 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
    • F15B13/0417—Load sensing elements; Internal fluid connections therefor; Anti-saturation or pressure-compensation 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
    • F15B2211/20—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
    • F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/25—Pressure control functions
    • F15B2211/253—Pressure margin control, e.g. pump pressure in relation to load 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
    • F15B2211/30—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
    • F15B2211/315—Directional control characterised by the connections of the valve or valves in the circuit
    • F15B2211/3157—Directional control characterised by the connections of the valve or valves in the circuit being connected to a pressure source, an output member and a return line
    • F15B2211/31576—Directional control characterised by the connections of the valve or valves in the circuit being connected to a pressure source, an output member and a return line having a single pressure source and a single output member
    • 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
    • F15B2211/321—Directional control characterised by the type of actuation mechanically
    • F15B2211/324—Directional control characterised by the type of actuation mechanically manually, e.g. by using a lever or pedal
    • 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
    • F15B2211/515—Pressure control characterised by the connections of the pressure control means in the circuit
    • F15B2211/5151—Pressure control characterised by the connections of the pressure control means in the circuit being connected to a pressure source and a 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
    • F15B2211/50—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
    • 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
    • F15B2211/6054—Load sensing circuits having valve means between output member and the load sensing circuit using shuttle 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
    • F15B2211/615—Filtering 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
    • 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S137/00—Fluid handling
    • Y10S137/906—Valves biased by fluid "springs"
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T137/00—Fluid handling
    • Y10T137/8593—Systems
    • Y10T137/87169—Supply and exhaust
    • Y10T137/87177—With bypass
    • Y10T137/87185—Controlled by supply or exhaust valve

Definitions

  • Butcher ABSTRACT A load-responsive hydraulic system for controlling a fluid actuated device, including at least one manual control valve and a differential pressure actuated bypass valve adapted to bypass excess fluid at a low differential pressure when no fluid is being directed to the fluid actuated device.
  • the bypass valve includes fluid-responsive means to automatically adjust the bypass valve to bypass fluid at a higher dif ferential pressure when a fluid motor is actuated and thereby extend the flow capacity of the manual control valve.
  • the present invention comprises an improvement of the load-responsive system described in U.S. Pat. No. 3,l45,734
  • the improved hydraulic system of the present invention is provided for use with load-responsive hydraulic control systems.
  • the hydraulic system includes a manual control valve in a working section that is adapted to sense load pressure at the motor port, and a difi'erential pressure controlled bypass valve which is responsive to the difference between pump pressure and hydraulic motor load pressure to bypass pump outlet fluid.
  • the improvement comprises a means of increasing the difference in pressure that is required to open the bypass valve when flow is directed to the fluid motor port. This increase in differential bypass pressure allows the control valve to be used for much higher flow rates because the higher differential bypass pressure is effective to force additional fluid from inlet port to a motor port.
  • the lower difi'erential bypass pressure when fluid is not directed to a motor port, reduces the power loss and heat rise that is attendant with higher differential bypass pressures.
  • FIG. 1 is a cross section of the preferred configuration of a working section portion of the hydraulic system
  • FIG. 1A is a schematic view of a portion of the working section of FIG. 1;
  • FIG. 2 is a schematic view of a complete hydraulic system including a bypass valve and two working sections incorporating the principles of the present invention
  • FIG. 3 is a cross section of the preferred configuration of the bypass valve
  • FIG. 4 is an enlarged view of a portion of the bypass valve of FIG. 3;
  • FIG. 5 is a cross section of a modified form of bypass valve
  • FIG. 6 is a cross section of a second modified form of bypass valve.
  • FIG. 1 there is illustrated a preferred embodiment of a working section 10 of a hydraulic system comprising a manual control valve.
  • Working section 10 includes movable valving element or valve spool 11, casing 12, inlet port. l3, motor port 14, second motor port 15, control port 16, second control port 17, sump or return ports l8, 19, load check valve 20, and pressure supply port 21.
  • Valve spool 11 is mounted within a bore in the casing, 12.
  • the bore 25 includes lands 27, 28, 29, and 31.
  • Valve spool 11 has lands 34, 35, 36, 37 and 38 thereon.
  • Lands and 37 have metering notches formed therein; and land 36 has notches 36A formed therein.
  • valve spool 11 is illustrated in FIG. 1 in its neutral position in which land 36 blocks the supply port 21. Further, the lands 35 and 37 in this position isolate the sump or return ports 18 and 19 from the motor ports 14 and 15.
  • valve spool 11. When valve spool 11. is moved to the right, for example to a first operating position, land 36 opens a fluid communication path between supply port 21 and motor port 14.
  • the restriction of this flow path defined by an edge of the land 36 or notches 36A and an edge of the supply port 21 can be varied by varying the position of spool l 1.
  • the first operating position of valve spool 11 includes movement of land 35 into the area of motor port 14.
  • Land 35 has a shorter effective length than motor port 14, thus load pressure in port 14 will be communicated around land 35 to control port 16.
  • the load pressure in the control port 16 comprises a control signal pressure to be utilized in controlling the effective input of fluid to port 13 or the effective output of the source of fluid supply, as will be described later.
  • the shorter efi'ective length of land 35 can be achieved by having the land shorter than the port 14, or by utilizing notches 40 in the land 35.
  • Movement of the valve spool 11 to the first operating position described also moves land 34 into the area of bore land 27 thus blocking communication between control port 16 and the sump 18 to prevent loss of control signal pressure in control port 16 through sump port 18.
  • a second operating position of the valve spool 11 is available when the valve spool 11 is moved to the left to establish a flow path between motor port 14 and sump port 18.
  • This flow path will be formed between the edge 350 or notches 41 of land 35 and edge 28a of bore land 28.
  • an unrestricted flow path is provided between the control port 16 and sump port 18 since spool land 34 has now moved to the left to open communication between control port 16 and sump port 18.
  • the control signal pressure in control port 16 at this time will be equal to sump pressure while fluid from the motor is being returned through motor port 14 to sump port 18.
  • valve spool 11 in the second operating position with regard to motor port 15 and its connection to supply port 21, control port 17, and sump port 19, is the same as described above for motor port 14.
  • the control ports 16 and 17 are thus operable to obtain a control signal pressure, the pressure being sump pressure when the respective motor ports 14 and 15 are isolated from supply port 21 and the control signal presure being equal to the load pressure in the respective motor port when the motor port 14 or 15 is in fluid communication with supply port 21.
  • both control ports 16 and 17 are in communication with their respective sump ports.
  • valve spool 11 As the valve spool 11 is moved to a position to connect one of the motor ports to the supply port, for example when spool 11 is moved to the right to connect motor port 14 with supply port 21, the control port 16 will contain a control signal pressure equal to the working pressure existing in motor port 14, and control port 17 will be in communication with sump port 19.
  • control port 17 When spool 11 is moved to the left to connect motor port 15 with supply port 21, control port 17 will be communicated with motor port 15, and control port 16 will be communicated with sump port 18.
  • the working section 10 illustrated in FIG. 1 incorporates a first logic system or means provided in the casing 12 which comprises control ports 16 and 17 and a shuttle valve 51.
  • Shuttle valve 51 includes a movable ball 52 and first and second ball seats53 and 54.
  • the valve 51 includes a control signal outlet port 56 and control signal inlet ports 57 and 58 which are connected to control ports 16-and '17 respectively.
  • the operation of the valve 51 is such that control port 16 or 17 having the highest control signal pressure therein will move the ball 52 to engage the opposite seat 54 or 53 to connect the highest control signal pressure to outlet port 56.
  • the three-port shuttle valve 51 is advantageous in that when the spool 11 is moved to a neutral position to remove or dissipate the control signal pressure the ball 52 will be unable to block both inlet ports 57 and 58 simultaneously and so the control signal pressure from the outlet port 56 will be unable to block both inlet ports 57 and 58 simultaneously and so the control signal pressure from the outlet port 56 will be able to reverse flow to one of the control ports 16 or 17. Since the spool lands 34 and 38 leave a communication path between the control ports 16 and 17 when the spool 11 is in neutral position, the reverse flow of the control signal pressure will continue to one of the sump ports 18 or 19, and can be seen that the first logic system is flow reversible.
  • spool land 34 and bore land 27 provides valved dissipation of the control signal. If spool land 34 entered bore land 27 in the neutral position, a small orifice could be provided to dissipate the control signal pressure. This type of structure is particularly described in copending application, Ser. No. 757,961 of common assignee. This would limit flow signal negation. Limitedflow signal dissipation is less desirable than valved signal dissipation because of the power loss caused by presure flow through the orifice.
  • valve control system When a plurality of working sections are provided in the valve control system, for actuating a plurality of fluid motors, for example, a second logic system must be provided to select the highest load pressure required by any of the valve working sections.
  • the second logic system 60 includes shuttle valves 64 in each of the working sections and 10A.
  • Each shuttle valve 64 includes an inlet port 56 which is the same as the outlet port of the first logic system 50, a further inlet port 61, outlet port 62 and a movable ball 63.
  • the inlet port 61 of the second logic system for this valve is connected to a sump conduit but the shuttle valve 64 of the last working section may be omitted.
  • shuttle valve 64 may be included for the purpose of standardizing production, but it has no function in the system, and it can be seen that the number of second logic shuttle valves that are required is one less than the number of working sections, and all of the second logic system shuttle valves, if more than one, are connected in series.
  • the outlet port 62 of the valve section 10A is connected by conduit 65 with the inlet port 61 of the shuttle valve 64 of the working section 10.
  • this pressure will be communicated through conduit 65, inlet port 61 of the shuttle valve 64 of working section 10 moving the ball 63 to seal off connection with inlet port 56 and connect the control signal pressure of working section 10A in conduit 65 to the outlet port 62, which is connected to a fluid control system including a bypass valve, as will be described later.
  • the highest control signal pressure is selected for the working section; by use of the second logic system 60 the highest control signal pressure of all working sections is selected for connection to the fluid control system.
  • This second logic system 60 is also flow reversible because both inlet ports of any of the three port shuttle valves 64 cannot be blocked by their shuttles.
  • a complete hydraulic system is illustrated having at least two working sections, 10 and 10A, as described above.
  • the system incorporates an improved differential pressure actuated bypass valve 80 which is illustrated in outline form only in FIG. 2.
  • a source of fluid supply or pump 100 is provided for the system which comprises a fixed displacement pump.
  • a fluid sump 101 is provided.
  • Pump 100 has an intake conduit 102 connected with sump 1 1.
  • Pump 100 is connected to the inlet port 13 of each of the working sections by a supply conduit 103.
  • a return conduit 109 is provided which connects the sump or return ports 18 and 19 of each working section with the sump. 101.
  • a filter 110 is illustrated in the return conduit 109.
  • Working section 10 is illustrated as controlling a fluid actuated device or hydraulic motor 112 and working section 10A is illustrated as controlling fluid actuated device or hydraulic motor 113.
  • Bypass valve 80 includes ports 81, 82 and 83. Port 81 is connected to the outlet port 62 of working section 10 by conduit 115. Port 82 of bypass valve 80 is connected to supply conduit 103 by branch circuit 116. Port 83 is connected to sump through conduit 109.
  • valve spools ll of working sections 10 or 10A are in their neutral positions fluid admitted through inlet port 13 will be blocked but will be admitted to one side of the motors 112 or 113 when the spools 11 are in one of their operating positions. Return flow from the motors 112 or 113 flows to sump through return conduit 109.
  • bypass valve 80 operates to bypass a certain amount of flow from the pump through port 83 to return conduit 109 in response to the pressure differential between the control signal pressure in port 81 and the pressure supplied to inlet ports 13.
  • bypass valve 80 works in a novel manner to bypass flow at an increased pressure differential when one of the control valves is supplying pressure to its respective fluid motor as compared to the actuating differential pressure at which valve 80 will bypass fluid when all of the valve spools 11 are in their neutral positions.
  • FIG. 3 one form of the improved bypass valve 80 is illustrated in detail. Ports 81, 82 and 83 of the valve 80 are connected to the respective conduits as described above.
  • Avalve casing is provided which has coaxial bore sections 121 and 122 therein.
  • a restriction or orifice 1 17 is provided in casing 120 and is connected in conduit 115 near port 81.
  • Slidable in the bore 121 is a bypass valve spool 124 which has a first fluid-responsive area 125 on the right end thereof and a second fluid-responsive area 126 on the left end thereof.
  • Valve spool 124 includes lands 129 and 130 separated by a grooved portion 131.
  • a drilled passage 133 connects grooved portion 131 with fluid-responsive area 125.
  • a pilot seat member 141 is provided having a central passage 142. External threads 143 are provided on pilot seat member 141 which engage threads 144 provided on spool 124 to secure seat member 141 in spool 124.
  • a valve poppet 146 is provided which has formed a conical seat surface 147 in one end thereof, the seat member 141 having an external circular edge 148 adapted to engage seat surface 147 to provide a fluid seal.
  • a spring 149 urges poppet 146 into engagement with seat structure 141.
  • a bore 150 connects the exterior of land 129 of spool 124 with the interior of spool 124 containing poppet 146.
  • the bore 121 includes a port 151 which connects to port 83 by a fluid passage 152.
  • a fluid piston 156 Provided in the bore 122, which is sealed by an end plug 154, is a fluid piston 156.
  • the piston 156 has a third fluid-responsive area 157 on the left side thereof.
  • a sealing shoulder 159 is provided on the opposite side of piston 156.
  • Integral with piston 156 is a push rod 160 which extends through casing 120 into bore 121 and has a flange 161 thereon within the bore 121.
  • a central longitudinal passage 163 extends the length of piston 156 and rod 160 to connect fluidresponsive area 157 with bore 121.
  • a spring 166 extends between flange 161 and spool 124.
  • a conical seat 168 is provided in casing 120 which is engageable by shoulder 159 to provide a fluid seal and to serve as a stop for piston 156.
  • a passage 170 in casing 120 extends between the seat 168 and fluid passage 152 connected to port 83.
  • bypass valve 80 The operation of the bypass valve 80 is as follows: fluid under pressure from pump 100 by means of supply conduit 116 enters at port 82 and is communicated through passage 133 to act on fluid-responsive area 125 which urges the spool 124 to the left communicating pump pressure from port 82 into port 151, passage 152 and port 83 to return conduit 109.
  • the pump output presure when working sections are in their neutral positions will be kept at a low level or standby pressure dependent upon the load of the spring 166.
  • the spool 124 responds to presure differential between the pump output pressure acting on fluid responsive area 125 and the control signal pressure in conduit 115 acting on second fluid responsive area 126. Since the control signal pressure in conduit 115 is negligible, being sump pressure at the time the working sections are in their neutral positions, as has been described earlier, only the force of the spring 166 opposes pump pressure on the fluid-responsive area 125.
  • spring 166 provides a bias force to move or to hold spool 124 to a position shutting off the bypass flow.
  • spring 166 may be shortened to allow full opening of the bypass valve without applying any bias force.
  • the load pressure of that particular motor which has the highest load pressure will be communicated through the first logic means 50 comprising control ports 16 and 17 and shuttle valves 64 to conduit 115 and to port 81, as described earlier.
  • This pressure acting on the second fluid-responsive area 126 is effective to increase the pump output pressure by increasing the pressure required on fluid-responsive area 125 to move spool 124 to the left, thereby increasing the bypass pressure level of bypass valve 80.
  • Bypass valve 80 includes a novel and improved fluidresponsive means which increases the pressure differential between port 82 and port 81 at which the bypass valve 80 will bypass fluid from the supply conduit 116.
  • the piston 156 includes third fluid-responsive area 157 thereon which the control signal pressure in port 81 is communicated through passage 163 in rod 160.
  • the highest load pressure is communicated to the third fluid-responsive area 157 which will move piston 156 to the right and increase the load spring 166 applied to spool 124.
  • This will, in effect, raise the differential pressure at which the bypass valve 80 will be activated to bypass pump output fluid.
  • the load pressure on the third fluid-responsive area 157 could be effective to increase the spring load such that a 100 p.s.i. pressure differential will be maintained between pump output pressure and load pressure by bypass valve 80.
  • the amount the spring or bias force can be increased is limited by the shoulder 159 contacting seat 168 providing a fluid seal and also limiting the movement of piston 156 to the right.
  • Bypass valve 80 may also be pilot actuated by pilot valve 140.
  • control signal or load pressure in port 81 is applied to poppet 146 via passage 142 to force poppet 146 away from circular edge 148. Fluid is then exhausted to sump via bore 150 in spool 124, port 151, and return port 83.
  • Flow through passage 142 is effective to limit the pressure in port 81 and the force developed against area 126 because of the restriction of orifice 117 so that spool 124 is moved to the left to a bypassing position when additional pressure occurs in port 82 and conduit 116 and additional force is developed by the fluid pressure applied to area 125. Therefore excess flow is bypassed and the effective output of the pump is controlled as a function of a predetermined maximum pressure as well as by differential pressure. In this way the bypass valve also serves as a pressure relief valve.
  • bypass valve 80 maintains a low pressure difi'erential when the fluid motors are not being actuated, i.e., the working sections in neutral positions, which is advantageous in that the power loss under neutral conditions is minimal.
  • bypass valve 180 in FIG. 5 is illustrated with like parts numbered the same as corresponding parts in bypass valve 80 of FIG. 3.
  • the second coaxial bore 122 of bypass valve 180 is on the right side of spool 124.
  • a piston 256 is slidable in bore 122 and has a push rod 260 thereon contacting the right end of spool 124.
  • Piston 256 has a fluid-responsive area 257 thereon corresponding to third fluid-responsive has a branch conduit 215 which is connected to the bore 122 at a point to place fluid-responsive area 257 in communication with the control signal pressure conduit 115.
  • a spring 258 is provided urging piston 256 to the left.
  • a passage 259 places bore 122 on the right side of piston 256 in communication with fluid passage 152 in port 83.
  • bypass valve The operation of the bypass valve is similar to bypass valve 80. Initially when the working sections are in their neutral positions and there is effectively a minimum pressure in control pressure conduit 115, spring 258 will act in opposition to spring 166 effectively reducing the net spring force on spool 124 thereby allowing spool 124 to bypass fluid pressure at a very low pressure differential between control pressure conduit 115 and pump pressure conduit 116. However, when a working section is actuated to operate a fluid motor the load pressure in conduit 115 will be connected through conduit 215 to fluid-responsive area 257 which will in turn move piston 256 to the right to effectively remove the influence of piston 256 and spring 258 from spool 124. Thus the full force of spring 166 is operative on spool 124 and the bypass valve 180 will then bypass fluid pressure at a higher pressure differential than when the working sections are in their neutral positions.
  • bypass valve 280 is illustrated with reference numerals identical to those used for corresponding elements of bypass valve 80.
  • Bypass valve 280 has a second bore 322 having a hollow balance piston 356 slidable therein.
  • a spring 358 is received within hollow piston 356 and urges the piston to the left into contact with spool 124.
  • Piston 356 has a fluid-responsive area 357 thereon on the side of the piston toward spool 124.
  • the opposite side of piston 356 is in communication with fluid passage 152 and thereby connected through port 83 to return conduit 109.
  • Bypass valve 280 operates in a similar manner to bypass valve 180. Initially spring 358 will urge piston 356 into engagement with spool 124 eflectively reducing the net spring force on spool 124 thereby bypassing fluid pressure from conduit 116 at a minimum value. Pressure in supply conduit 116 is applied through passage 133 to fluid-responsive area 157 but is at a minimum and does not overcome the force of spring 358.
  • bypass valve 280 When a fluid motor is actuated and load presure exists in control signal pressure conduit 115 the pump pressure, as described earlier, will be increased and this presure acting on fluid-responsive area 357 will move piston 356 to the right overcoming the force of spring 358 and allowing spring 166 to exert its full force on spool 124, thereby raising the differential pressure maintained by bypass valve 280. No mechanical stop is needed to limit the change in bypass pressure caused by applying fluid pressure to third area 357 of balance piston 356 because the change in bypass pressures becomes a maximum when balance piston 356 no longer engages spool 124. Likewise, a stop is not required in bypass valve 180 of FIG.
  • Bypass valve 280 of FIG. 6 is different in operation than either of the other two designs in that the control signal pressure is used in an indirect manner to change the differential pressure.
  • the control signal or load pressure in port 81 increases the pump presure by restricting flow from port 82 to port 83. This increase in pressure in port 82 is effective to actuate balance piston 356.
  • the pump or valve inlet pressure that is applied to third fluid-responsive area 357 that actuates the fluid-responsive means to achieve an increase in the differential bypass pressure.
  • control valve system including an improved and advantageous form of bypass valve which is operative in a load area 157 of bypass valve 80.
  • Control signal pressure conduit 75 responsive type of control to extend the flow capacity of the valves in the working sections by including the novel flowresponsive means to increase the differential pressure maintained by the bypass valve when the fluid motors are being actuated.
  • the bypass valve will bypass fluid pressure at a minimum differential pressure when the fluid motors are not being a tuated so as to keep pumping losses to a minimum when the system is in neutral condition.
  • a hydraulic control system having a control valve with pressure inlet, motor, and fluid return ports and a movable valving element; said system including a differential pressure actuated bypass valve operatively associated with said control valve mechanism and a source of fluid supply connected to said inlet port, said bypass valve being connected to said source of supply and said pump, said bypass valve adapted to be connected to said motor port whereby said bypass valve is operative to bypass fluid from said source to said sump as a function of the difference in fluid pressure between said inlet port and said motor port, and said bypass valve including fluid-responsive means responsive to fluid pressure in said motor port and adapted to modify said difference in fluid pressure at which said bypass valve will bypass fluid.
  • a hydraulic system as claimed in claim 1 including bias force means adapted to act on said bypass valve to oppose said bypassing of fluid.
  • bypass valve includes first and second fluid-responsive areas connected to said inlet and said sump port to control the bypassing of fluid from said inlet port to said sump port, and said fluid-responsive means comprising a third fluid-responsive area.
  • a hydraulic system as claimed in claim 4 wherein logic means are provided connecting said third fluid-responsive area to said motor port to provide additional force on said bypass valve opposing the bypassing of fluid whereby said difference in pressure at which said bypass valve will bypass fluid is increased.
  • a bypass valve operatively associated with said control valve mechanism, a source of fluid supply connected to said inlet port, said movable valving element having a first position isolating said inlet port from said motor port and a second position connecting said inlet port to said motor port, said bypass valve being connected to said source of supply and said sump, said system including a logic system connecting said bypass valve to said motor port whereby said bypass valve is operative to bypass fluid from said source to said sump as a function of a predetermined difference in fluid pressure between the pressure at said inlet port and the pressure in said logic system when said movable valving element is in said first or second position, and said bypass valve including fluidresponsive means responsive to the pressure in said motor port to increase said predetermined difl'erence in fluid pressure at which said bypass valve will bypass fluid when said movable valving element is in said second position.
  • a hydraulic system as claimed in claim 6 including bias force adapted to act on said bypass valve to oppose said bypassing of fluid.
  • bypass valve includes first and second fluid-responsive areas connected to said inlet port and said logic system to control the bypassing of fluid from said inlet port to said sump port, and said fluid-responsive means comprising a third fluidresponsive area.
  • a hydraulic system as claimed in claim 8 wherein said logic system connects said third fluid-responsive area to said motor port when said movable valving element in said second position.
  • a bypass valve operatively associated with said control valve, a source of fluid supply connected to said inlet port, a logic system including a control port in said control valve, said movable valving element having a first position isolating said inlet port from said motor port, said movable valve element having a second position connecting said inlet port to said motor port and said motor port to said control port, said bypass valve being connected to said source of supply and said sump, said logic system connecting said control port to said bypass valve whereby said bypass valve is operative to bypass fluid from said source to said sump as a function of a predetermined difference in fluid pressure between the pressure at said inlet port and the pressure at said control port when said movable valving element is in said first and second positions, and said bypass valve including fluid-responsive means responsive to said pressure in said control port and adapted to increase said predetermined difference in fluid pressure at which said bypass valve will bypass fluid when
  • a hydraulic system as claimed in claim 10 in which said logic system establishes a fluid communication path between said control port and said sump to dissipate the fluid pressure in said control port when said movable valving element is in said first operating position, whereby said bypass valve is operative to bypass fluid as a function of the difference between the fluid pressure in said inlet port and said sump when said movable valving element is in said first operating position.
  • bypass valve includes first and second fluid-responsive areas connected to said inlet and sump ports to control the bypassing of fluid from said inlet port to said sump port, and said fluid-responsive means comprising a third fluid-responsive area.
  • a hydraulic system as claimed in claim 11 including a second motor port and a second control port; said fluidresponsive means being connected to both of said control ports by means of a three-port shuttle valve.
  • a hydraulic system including a plurality of control valve working sections each including inlet, motor, and fluid return ports and a movable valving element; a source of fluid supply connected to said inlet port, a sump connected to said return ports, a bypass valve operatively associated with said control valve mechanism and having first and second fluidresponsive areas and adapted to control the bypassing of fluid pressure from said supply source to said sump as a function of the difi'erence in pressure applied to said areas, conduit means establishing fluid communication between said inlet port and said first area, logic means adapted to select the highest motor port pressure of any of said motor ports that are in communication with said inlet port whenever at least one of said motor ports is in communication with said inlet port and to apply said highest motor port pressure to said second area; said logic means being adapted to dissipate the fluid pressure applied to said second area when all motor ports are isolated from their respective inlet ports, and said bypass valve including fluidresponsive means sensitive to the fluid pressure selected by said logic means to increase said difference in fluid pressures required to actu
  • a hydraulic system as claimed in claim 16 in which said logic means dissipates the fluid applied to said second area by means of a fluid communication path established by one of said movable valving elements.
  • a hydraulic system including a control valve; said control valve having pressure inlet, motor, and fluid return ports; a source of fluid supply and a sump, said source being connected to said inlet port, said control valve controlling the fluid pressure in said inlet and motor ports; a difierential pressure actuated bypass valve operatively connected to said motor port, to said source, and to said sump and efl'ective to bypass fluid from said source to said sump as a function of the difference in fluid pressure between that in said inlet port and that in said motor port; and a fluid-responsive means in said bypass valve connected to be responsive to the fluid pressures in one of the ports of said control valve and adapted to modify the difference in fluid pressure at which said bypass valve will bypass fluid from said source to said sump.
  • 10 jected end areas comprising said first and second fluid-responsive areas and bias means acting on said piston with a predetermined force; said fluid-responsive means including a balance piston also acting on said spool; said pressure in said inlet port connected to said balance piston to thereby change the effect of said bias means on said spool whereby the difference in pressure at which said bypass valve will bypass fluid from said inlet port to said sump will be varied in response to the pressure in said inlet port.

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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)
  • Servomotors (AREA)
  • Multiple-Way Valves (AREA)
US3631890D 1970-04-06 1970-04-06 Flow extending bypass valve Expired - Lifetime US3631890A (en)

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US2577970A 1970-04-06 1970-04-06

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AR (1) AR204384A1 (xx)
BE (1) BE765306A (xx)
CA (1) CA919055A (xx)
DE (1) DE2116395C3 (xx)
FR (1) FR2085875B1 (xx)
GB (1) GB1306886A (xx)
NL (1) NL168305C (xx)
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Cited By (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3742982A (en) * 1971-07-26 1973-07-03 Borg Warner Control valve
US3777773A (en) * 1972-02-22 1973-12-11 Koehring Co Pressure compensating valve mechanism
DE2335704A1 (de) * 1972-07-13 1974-01-24 Borg Warner Hydraulikanlage
DE2260457A1 (de) * 1972-12-11 1974-06-12 Wabco Westinghouse Gmbh Stromteilereinrichtung fuer ein hydrauliksystem mit mehreren unterschiedlich belastbaren verbrauchern
US3827453A (en) * 1972-05-05 1974-08-06 Parker Hannifin Corp Directional control valve
US3878864A (en) * 1973-12-07 1975-04-22 Borg Warner Bypass valve
DE2420242A1 (de) * 1974-04-26 1975-11-06 Bosch Gmbh Robert Hydraulische steuerschiebervorrichtung
US3942413A (en) * 1974-08-01 1976-03-09 Borg-Warner Corporation Load limiting system
US3971216A (en) * 1974-06-19 1976-07-27 The Scott & Fetzer Company Load responsive system with synthetic signal
US4111198A (en) * 1977-06-02 1978-09-05 Alvin J. Marx Automated intravenous fluid regulating and administering apparatus
US4145958A (en) * 1977-12-02 1979-03-27 Borg-Warner Corporation Fluid control system with automatically actuated motor port lock-out valves
DE2930390A1 (de) * 1978-07-27 1980-02-14 Borg Warner Stroemungsmittelsystem und steuermechanismus fuer ein stroemungsmittelsystem
US4209039A (en) * 1978-04-10 1980-06-24 Tadeusz Budzich Load responsive control valve
US4216797A (en) * 1978-04-10 1980-08-12 Tadeusz Budzich Load responsive control valve
US4303091A (en) * 1979-03-01 1981-12-01 Barmag Barmer Maschinenfabrik Hydraulic control apparatus for load independent flow regulation
US4649951A (en) * 1984-07-03 1987-03-17 Maurice Tardy Assisted slide for pressure compensation in a hydraulic distributor
US4798126A (en) * 1987-03-23 1989-01-17 Caterpillar Inc. Load responsive system using load responsive pump control of a bypass type
EP2446151A1 (en) * 2009-06-24 2012-05-02 Nordhydraulic AB Method and device for controlling a hydraulic system
US8627728B2 (en) 2012-01-31 2014-01-14 Hammonds Technical Services, Inc. System for determining the flow rate in a fluid with liquid additives using reciprocating positive-displacement flow meter
EP4170188A1 (en) * 2021-10-21 2023-04-26 Bucher Hydraulics S.p.A. Inlet section for use in a hydraulic distributor
US12123502B2 (en) 2021-10-21 2024-10-22 Bucher Hydraulics S.P.A Inlet section for use in a hydraulic distributor

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2611216C2 (de) * 1976-03-17 1981-12-03 G.L. Rexroth Gmbh, 8770 Lohr Vorrichtung zur kavitationsfreien Druckbegrenzung von Arbeitsflüssigkeit
JPS57146827U (xx) * 1981-03-12 1982-09-14
JPS5859430U (ja) * 1981-10-19 1983-04-21 ヤンマー農機株式会社 コンバインニオケル刈取部の連結構造
DE3611973C2 (de) * 1986-04-09 1994-04-14 Rexroth Mannesmann Gmbh Nebenschlußventil

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3145627A (en) * 1960-10-26 1964-08-25 Schlatter Ag Control apparatus for welding machines and the like
US3145734A (en) * 1961-10-06 1964-08-25 Borg Warner Pressure compensated flow control valve
US3160167A (en) * 1962-02-16 1964-12-08 Parker Hannifin Corp Valve assembly
US3212523A (en) * 1963-09-27 1965-10-19 Parker Hannifin Corp Fluid system and relief valve assembly therefor
US3304633A (en) * 1964-05-08 1967-02-21 Caterpillar Tractor Co Hydraulic circuit
US3467126A (en) * 1966-03-21 1969-09-16 Hydranamic Systems Corp Hydraulic load compensating directional control valve

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2503870A (en) * 1946-05-03 1950-04-11 Vickers Inc Flow regulating device

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3145627A (en) * 1960-10-26 1964-08-25 Schlatter Ag Control apparatus for welding machines and the like
US3145734A (en) * 1961-10-06 1964-08-25 Borg Warner Pressure compensated flow control valve
US3160167A (en) * 1962-02-16 1964-12-08 Parker Hannifin Corp Valve assembly
US3212523A (en) * 1963-09-27 1965-10-19 Parker Hannifin Corp Fluid system and relief valve assembly therefor
US3304633A (en) * 1964-05-08 1967-02-21 Caterpillar Tractor Co Hydraulic circuit
US3467126A (en) * 1966-03-21 1969-09-16 Hydranamic Systems Corp Hydraulic load compensating directional control valve

Cited By (29)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3742982A (en) * 1971-07-26 1973-07-03 Borg Warner Control valve
US3777773A (en) * 1972-02-22 1973-12-11 Koehring Co Pressure compensating valve mechanism
US3827453A (en) * 1972-05-05 1974-08-06 Parker Hannifin Corp Directional control valve
DE2335704A1 (de) * 1972-07-13 1974-01-24 Borg Warner Hydraulikanlage
DE2260457A1 (de) * 1972-12-11 1974-06-12 Wabco Westinghouse Gmbh Stromteilereinrichtung fuer ein hydrauliksystem mit mehreren unterschiedlich belastbaren verbrauchern
US3878864A (en) * 1973-12-07 1975-04-22 Borg Warner Bypass valve
DE2420242A1 (de) * 1974-04-26 1975-11-06 Bosch Gmbh Robert Hydraulische steuerschiebervorrichtung
US3971216A (en) * 1974-06-19 1976-07-27 The Scott & Fetzer Company Load responsive system with synthetic signal
US3942413A (en) * 1974-08-01 1976-03-09 Borg-Warner Corporation Load limiting system
US4111198A (en) * 1977-06-02 1978-09-05 Alvin J. Marx Automated intravenous fluid regulating and administering apparatus
US4145958A (en) * 1977-12-02 1979-03-27 Borg-Warner Corporation Fluid control system with automatically actuated motor port lock-out valves
US4216797A (en) * 1978-04-10 1980-08-12 Tadeusz Budzich Load responsive control valve
US4209039A (en) * 1978-04-10 1980-06-24 Tadeusz Budzich Load responsive control valve
US4193263A (en) * 1978-07-27 1980-03-18 Borg-Warner Corporation Fluid control system with individually variable flow control mechanism for each control section
DE2930390A1 (de) * 1978-07-27 1980-02-14 Borg Warner Stroemungsmittelsystem und steuermechanismus fuer ein stroemungsmittelsystem
US4303091A (en) * 1979-03-01 1981-12-01 Barmag Barmer Maschinenfabrik Hydraulic control apparatus for load independent flow regulation
US4355655A (en) * 1979-03-01 1982-10-26 Barmag Barmer Maschinenfabrik Hydraulic control apparatus for load independent flow regulation
US4649951A (en) * 1984-07-03 1987-03-17 Maurice Tardy Assisted slide for pressure compensation in a hydraulic distributor
US4798126A (en) * 1987-03-23 1989-01-17 Caterpillar Inc. Load responsive system using load responsive pump control of a bypass type
CN102803748A (zh) * 2009-06-24 2012-11-28 诺德液压股份公司 用于控制液压系统的方法和装置
EP2446151A1 (en) * 2009-06-24 2012-05-02 Nordhydraulic AB Method and device for controlling a hydraulic system
EP2446151A4 (en) * 2009-06-24 2014-03-12 Nordhydraulic Ab METHOD AND DEVICE FOR CONTROLLING A HYDRAULIC SYSTEM
CN102803748B (zh) * 2009-06-24 2015-10-21 诺德液压股份公司 用于控制液压系统的方法和装置
US8627728B2 (en) 2012-01-31 2014-01-14 Hammonds Technical Services, Inc. System for determining the flow rate in a fluid with liquid additives using reciprocating positive-displacement flow meter
US8695434B2 (en) 2012-01-31 2014-04-15 Hammonds Technical Services, Inc. Fluid additive delivery system powered by the flowing fluid
EP4170188A1 (en) * 2021-10-21 2023-04-26 Bucher Hydraulics S.p.A. Inlet section for use in a hydraulic distributor
EP4279750A1 (en) 2021-10-21 2023-11-22 Bucher Hydraulics S.p.A. Inlet section for use in a hydraulic distributor
US11852249B2 (en) 2021-10-21 2023-12-26 Bucher Hydraulics S.P.A Inlet section for use in a hydraulic distributor
US12123502B2 (en) 2021-10-21 2024-10-22 Bucher Hydraulics S.P.A Inlet section for use in a hydraulic distributor

Also Published As

Publication number Publication date
FR2085875B1 (xx) 1976-02-06
JPS5545762B1 (xx) 1980-11-19
AR204384A1 (xx) 1976-02-06
NL168305B (nl) 1981-10-16
BE765306A (fr) 1971-10-05
DE2116395A1 (de) 1971-11-04
GB1306886A (en) 1973-02-14
DE2116395C3 (de) 1978-12-21
DE2116395B2 (de) 1978-04-27
SE370767B (xx) 1974-10-28
FR2085875A1 (xx) 1971-12-31
NL7104578A (xx) 1971-10-08
ZA712206B (en) 1971-12-29
NL168305C (nl) 1982-03-16
CA919055A (en) 1973-01-16

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