Classifications

• • 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
  • F15B11/02—Systems essentially incorporating special features for controlling the speed or actuating force of an 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
  • F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
  • F15B2211/205—Systems with pumps
• • 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
  • F15B2211/50518—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means using pressure relief 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
  • F15B2211/50—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
  • F15B2211/505—Pressure control characterised by the type of pressure control means
  • F15B2211/50554—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure downstream of the pressure control means, e.g. pressure reducing 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
  • F15B2211/515—Pressure control characterised by the connections of the pressure control means in the circuit
  • F15B2211/5153—Pressure control characterised by the connections of the pressure control means in the circuit being connected to an output member and a directional control valve
  • F15B2211/5154—Pressure control characterised by the connections of the pressure control means in the circuit being connected to an output member and a directional control valve being connected to multiple ports of an 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
  • F15B2211/50—Pressure control
  • F15B2211/515—Pressure control characterised by the connections of the pressure control means in the circuit
  • F15B2211/5159—Pressure control characterised by the connections of the pressure control means in the circuit being connected to an output member and a 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
  • F15B2211/52—Pressure control characterised by the type of actuation
  • F15B2211/528—Pressure 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
  • F15B2211/57—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
  • F15B2211/70—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

Definitions

• the present invention relates to a compensation valve.
• Hydraulic servosystems normally include double-acting hydraulic piston-cylinder devices, where pressure acts simultaneously on both sides of the piston, wherewith the force at which the piston rod acts on a load corresponds to the pressure difference across the piston and the areas of the piston on both sides thereof.
• Two opera- tional states occur in this case, namely a first state in which the piston rod is pressed against a load, Jand a second state in which the piston rod pulls or draws in a load.
• the present invention provides a very simple hydraulic component for effecting such compensation in a simple and positive fashion.
• This ccanpensation may be effected by completely balancing out changes in pressure, although overcxarpensation or under ⁇ mpensation can also be effected.
• the present invention affords an effective solution to the above mentioned problem, since it also functions as a safety means.
• the present invention relates to a compensation valve for hydraulic servosystems in which pressure is intended to be applied on both sides of a double--acting hydraulic piston-cylinder device, said valve being intended to compensate for a pressure change on one side of the piston with a pressure change on the other side of said piston, the invention being characterized in that the compensation valve comprises a cylinder which includes an elongated plunger whose one end faces tc-wards a first chamber and the other end faces towards a second chamber; in that one section of the valve cylinder has a larger diameter than the diameter of the plunger at said section, said section being connected with a channel intended for connection to a tank or reservoir; in that said section is located between said chambers such that in one axial position of displacement the plunger will permit pressure medium to pass from the first chamber and through said section to said tank; and in that the diameter of the plunger and cylinder of the compensation valve that end thereof which faces tcwards the first chamber differs from a corresponding diameter at that end which faces towards the second chamber,
• FIGS 1 and 2 illustrate an inventive compensation valve 1, 2 and show the valve incorporated in a hydraulic system, which has been greatly simplified graphically for the sake of clarity.
• the valve illustrated in Figure 1 has a different configuration to the valve illustrated in Figure 2, although both valves have principally the same design. As will be explained herebelow, the differences reside in the fact that the valve shown in Figure 1 is intended for use in conjunction with a hyraulic piston-cylinder device 3 with which the device is activated with pressure acting on that side 4 of the piston 5 having the largest piston area. In contra-di ⁇ tin ⁇ tion hereto, the valve illustrated in Figure 2 is intended for use with a hydraulic piston-cylinder device which is activated with pressure on that side 6 of the piston 5 having the smallest piston area.
• the inventive compensation valve is intended for use in hydraulic servosystems where pressure is intended to be applied on both sides of the piston of a double-acting hydraulic piston-cylinder device 3.
• the valve 1, 2 is intended to compensate for pressure changes on one side of the piston 5 of said device 3 with a pressure change on the other side of said piston.
• a pressure reduction valve 7 between a pump (not shown) and a first side 4 of the piston 5 where the force gener ⁇ ated by the device 3 is controlled.
• the other side 6 of the piston is connected to a pressurized hydraulic unit, illustrated by the line 10.
• the line, or pipe, extending from the pump or a pressurized conduit within the hydraulic system to the pressure reduction valve 7, 8 is referenced 11.
• the compensation valve l, 2 comprises a cylinder 20 which contains an elongated plunger 21 whose one end 22 faces tcwards a first chamber 23 and whose other end 24 faces towards a second chamber 25.
• the first chamber 23 which is connected to the pressure reduction valve 7, 8.
• the valve cylinder 20 has a section 26 of greater diameter than the diameter of the plunger 21 at said section.
• the section 26 is connected to a channel 27 which is intended for ⁇ nriecti ⁇ n to a tank or reservoir 28.
• the section 26 is located between said chambers 23, 25, such that in one axially displaced position the plunger 21 wil permit pressure medium to pass from the first chamber 23, through said section 26 and into the tank 28.
• the diameter of the plunger 21 and the cylinder 20 of said valve at that end 22 which faces tcwards the first chamber 23 differs from a corresponding diameter at that end 24 which faces tcwards the second chamber 25.
• the first chamber 23 of the compensation valve is intended to be connected, via a line 29, to a hydraulic component which is intended to control the pressure on said first side 4 of the piston 5 of the hydraulic piston-cylinder device.
• This hydraulic component is repres ⁇ ented in Figures 1 and 2 by a known pressure reduction valve.
• the line is connected to the channel of the pressure reduction valve that leads to the tank, this channel thus forming a control channel.
• the pressure reduction valve is constructed in a known manner such that the pressure acting on the surface 4 of the piston 5 will be equal to the basic pressure to which the pressure reduction valve 7 is set plus the pressure that prevails in the line 29.
• the other chamber 25 of the compensation valve i ⁇ intended for connection to said other ⁇ ide 6 of the pi ⁇ ton 5 of said device 3.
• the compensation valve includes a housing 31 having a cylindrical barrel whose diameter inwardly of the first chamber 23 differs frcm the diameter inwardly of the second chamber 24. Between these part ⁇ of the cylinder barrel the barrel presents a widened part 32 whose diameter is larger than the aforesaid diameter ⁇ . This widened part is connected to a channel 33 intended for connection to the tank or re ⁇ ervoir 28. Oil which leak ⁇ pa ⁇ t the pi ⁇ ton, primarily from the second chamber 25, is drained through the widened part 32. The aforesaid section 26 is located between the widened part 32 and the first chamber 23.
• the ratio between the smaller and larger areas of the plunger 21 of the c ⁇ pen ⁇ ation valve 1 is equal to the ratio between the smaller and the larger areas of the piston 5 of the hydraulic piston-cylinder device 3 on both ⁇ ides of ⁇ aid piston.
• the piston-cylinder device 3 will constantly exert the same force F onto an object, this force being determined by the basic pressure to which the pressure reduction valve 7 is set and which acts on the larger area 4 of the piston of said device 3, i.e. on the ⁇ o-called po ⁇ itive ⁇ ide of ⁇ aid pi ⁇ ton-cylinder device, irre ⁇ pective of whether or not a c ⁇ unterpre ⁇ ure occur ⁇ in the line 10.
• the pressure reduction valve 7 is set to a given pressure which result ⁇ in the pi ⁇ ton rod 30 actin ⁇ ; again ⁇ t an object at a given force F and that no pre ⁇ ure prevails in the line 10, i.e. on the so-called minus side of the piston-cylinder device.
• the plunger 22 will then be pressed to the right in Figure 1, whereupon pressure medium, such as oil, will drain through the line 29, the first chamber 23, through said section 26 and along the channel 27 to the tank 28.
• the maximum leakage that occurs will ⁇ u ⁇ tain the pressure on the plus ⁇ ide of the pi ⁇ ton-cylinder device, through the pre ⁇ ure reduction valve 7.
• the ⁇ ame pressure as that prevajj-ing in the line 10 will occur in the second chamber 25, which acts on the plunger 21 and moves it to the left in Figure 1.
• the leakage flow from the first chamber 23 to the tank 28 will decrease as a result hereof, therewith causing the pressure in the line 29 to increase.
• the pre ⁇ ure on the plus side of the hydraulic piston-cylinder device will therewith be increased by the pressure acting in the ine 29.
• the position of the plunger will be stabilized when the pres ⁇ ure in the fir ⁇ t chamber 23 multiplied by the area of the plunger 21 at the end thereof facing towards the first chamber is equal to the pressure in the second chamber 25 multiplied by the area of the plunger 21 on its surface 24 facing tcwards the second chamber.
• the cxjunterpressure will be fully compensated such that the force F will remain the smae.
• a complete balancing of the pressures is achieved in thi ⁇ ca ⁇ e.
• the plunger 21 of the compensation valve is constructed so that the ratio of the ⁇ aller pi ⁇ ton area 22 to the larger pi ⁇ ton area 24 of ⁇ aid compensation valve differs from the ratio of the smaller piston area 6 to the larger piston area 4 of the hydraulic piston-cylinder device 3 en opposite ⁇ ide ⁇ of the piston 5.
• the pressure on the plus side of the pi ⁇ ton- cylidner device will increa ⁇ e to a greater extent than i ⁇ corresponded by the counterpressure in the line 10, and consequently the force at which the piston 5 of the device 3 is forced out will be greater, despite the applied counterpres ⁇ ure.
• the aforede ⁇ cribed compensation is an ⁇ verc ⁇ mpen ⁇ ation.
• the area ⁇ of the plunger of the compensation valve can be chosen so a ⁇ to obtain an undercompensation.
• the plunger area ⁇ of the compensation valve can be chosen to provide the de ⁇ ired effect.
• Figure 3 exemplifies the use of the ⁇ apensation valve in conjunction with a pressure limiting valve 40.
• the line 29 is connected to the pressure limitation valve 40.
• This valve is of a suitable known kind and is constructed in a manner which enables the valve to be ⁇ et to a basic setting in which a given maximum pres ⁇ ure is allowed on the plus side 4 of the hydraulic piston-cylinder device when no pre ⁇ ure prevail ⁇ in the line 29.
• the valve is so constructed that when pressure prevails in the line 29, due to the cxxairrence of a counterpressure en the minus side of the piston-cylinder device, the maximum pressure per ⁇ mitted fcy the pressure limitation valve is increased.
• the pressure prevailing in the line 41 will correspond to the basic pre ⁇ ure ⁇ etting of the valve plu ⁇ the pre ⁇ ure prevailing in the line 29.
• the c ⁇ mpen ⁇ ation valve can be u ⁇ ed in that ca ⁇ e when the pre ⁇ ure applied to the hydraulic pi ⁇ ton-cylinder device 3 i ⁇ limited by a pressure limiting valve mounted instead on the minus side of the piston-cylinder device.
• a compensation valve of the principle design illustrated in Figure 2 shall be al ⁇ o u ⁇ ed in thi ⁇ case.
• c ⁇ mpen ⁇ ation valve can be connected in parallel across one or more hydraulic piston-cylinder devices in any hydraulic system whatsoever in which it is de ⁇ ired to c ⁇ mpen ⁇ ate for occurrent counterpre ⁇ ure ⁇ .

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Fluid Mechanics (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Actuator (AREA)
• Fluid-Pressure Circuits (AREA)

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Publications (1)

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Family Applications (1)

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Citations (3)

• 1990
  • 1990-02-19 SE SE9000592A patent/SE465328B/sv not_active IP Right Cessation
• 1991
  • 1991-02-18 WO PCT/SE1991/000119 patent/WO1991012449A1/en unknown

Patent Citations (3)

Non-Patent Citations (1)

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