EP0226125B1 - Variable displacement pump system - Google Patents

Variable displacement pump system Download PDF

Info

Publication number
EP0226125B1
EP0226125B1 EP86116785A EP86116785A EP0226125B1 EP 0226125 B1 EP0226125 B1 EP 0226125B1 EP 86116785 A EP86116785 A EP 86116785A EP 86116785 A EP86116785 A EP 86116785A EP 0226125 B1 EP0226125 B1 EP 0226125B1
Authority
EP
European Patent Office
Prior art keywords
pressure
pump
load
sensing
compensator
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.)
Expired - Lifetime
Application number
EP86116785A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0226125A2 (en
EP0226125A3 (en
Inventor
Lael Brent Taplin
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.)
Vickers Inc
Original Assignee
Vickers Inc
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Vickers Inc filed Critical Vickers Inc
Publication of EP0226125A2 publication Critical patent/EP0226125A2/en
Publication of EP0226125A3 publication Critical patent/EP0226125A3/en
Application granted granted Critical
Publication of EP0226125B1 publication Critical patent/EP0226125B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B1/00—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders
    • F04B1/12—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinder axes coaxial with, or parallel or inclined to, main shaft axis
    • F04B1/26—Control
    • F04B1/30—Control of machines or pumps with rotary cylinder blocks
    • F04B1/32—Control of machines or pumps with rotary cylinder blocks by varying the relative positions of a swash plate and a cylinder block
    • F04B1/324—Control of machines or pumps with rotary cylinder blocks by varying the relative positions of a swash plate and a cylinder block by changing the inclination of the swash plate

Definitions

  • This invention relates to a variable displacement pump control system comprising the features of the preamble to claim 1.
  • Such a system is known from US-A-3,067,693 with a larger area piston as the controlled positioning piston and an opposing smaller area positioning piston without a spring biasing the piston.
  • a spring is however known in the art (see Fig. 1).
  • Such systems usually are also provided with a pressure compensator for operating a hydraulic positioning piston to decrease the displacement of the pump and for overriding the load sensing compensator which is active as the primary pump control except when the pressure of the pump is at the limit set by the pressure compensator.
  • pump outlet is directly connected to the smaller area piston and to the supply line which includes the system valve.
  • the problem underlying the present invention is to provide a variable displacement pump control system which is more stable.
  • the load pressure as taken from a load sensing passage or downstream from the system valve is connected to the spring biased (or smaller area) piston rather than directly connecting the pump outlet to the spring biased piston.
  • variable displacement pump from which an outlet 10 is shown may be of the variable axial piston type and comprises a yoke and a swash plate 11 that are movable to vary the stroke of axial pistons (not shown).
  • a first smaller area spring biased positioning piston 12 is acted upon by pressure and yieldingly urges the yoke and the swash plate 11 to a maximum displacement position.
  • a second larger area positioning piston 13 acts on the yoke and the swash plate 11 in opposition to the first spring biased positioning piston 12.
  • Working fluid from the pump outlet 10 flows through a supply line 14 to a directional system or valve 15 and further to a load such as a hydraulic actuator.
  • a short passage or line 16 connects the pump outlet 10 to the first spring biased positioning piston 12.
  • pump outlet pressure is connected through a pump pressure sensing line 17 to a pressure compensator 18 and through a line section 17a, to a load sensing compensator 19.
  • the pressure compensator 18 may include a pilot valve 22 which opens at the pressure limit, set by its spring force and relieves the spring chamber of the pressure compensator 18 so that the spool thereof travels to the right hand side connecting line 17 to a line section 17c and further to the larger area positioning piston 13 which destrokes the pump (protection against overpressure).
  • Line section 17a of the pump pressure sensing line 17 is connected to the first spool end 19a of load sensing compensator 19 and to pump outlet pressure.
  • the second spool end 19b is connected by a load pressure sensing line 20 downstream of the system valve 15 to the pressure of fluid being delivered to the load.
  • compensator 19 which functions to modulate pump outlet pressure in lines 17, 17a and to deliver such modulated or control pressure via lines 17b, 17c to the second positioning piston 13. Modulation also depends on the spring preload of compensator 19.
  • the second positioning piston 13 which is larger in cross section than the first positioning piston 12 determines the position of the yoke and swash plate 11 and therefore pump delivery rate.
  • the displacement is varied in a manner to deliver exactly the load flow required by the actuator or actuators at the load pressure, which is, for example, 14 to 21 bar (200 to 300 p.s.i.) below the pump outlet pressure.
  • the load pressure which is, for example, 14 to 21 bar (200 to 300 p.s.i.) below the pump outlet pressure.
  • a load pressure line 21 is added which extends from the load pressure sensing line 20 downstream of the system valve 15 to the first positioning piston 12 which, therefore, is acted upon by load pressure.
  • any change in the flow rate has a simultaneous influence on both positioning pistons 12 and 13, i. e. changes in the load pressure and in the modulated pressure will arrive practically simultaneously at the first positioning piston 12 and the second positioning piston 13, respectively, whereas it is believed that in the prior art system the influence on the first piston 12 (pump outlet pressure) is followed with a time lag by the influence on the second piston 13 (modulated or control pressure) so that the position of the swash plate 11 is changed in one direction immediately followed by a change in the other direction which might be the reason for the pulsations observed.
  • variable displacement pump of the swash plate type
  • pump adjusting mechanism for varying the displacement
  • eccentric adjustment variable vane pumps and pumps using a rotating group housed in a tiltable yoke assembly.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Control Of Positive-Displacement Pumps (AREA)
  • Reciprocating Pumps (AREA)
  • Fluid-Pressure Circuits (AREA)
EP86116785A 1985-12-13 1986-12-03 Variable displacement pump system Expired - Lifetime EP0226125B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US80852785A 1985-12-13 1985-12-13
US808527 1991-12-16

Publications (3)

Publication Number Publication Date
EP0226125A2 EP0226125A2 (en) 1987-06-24
EP0226125A3 EP0226125A3 (en) 1989-07-05
EP0226125B1 true EP0226125B1 (en) 1991-04-03

Family

ID=25199037

Family Applications (1)

Application Number Title Priority Date Filing Date
EP86116785A Expired - Lifetime EP0226125B1 (en) 1985-12-13 1986-12-03 Variable displacement pump system

Country Status (6)

Country Link
EP (1) EP0226125B1 (enrdf_load_stackoverflow)
JP (1) JPH0819922B2 (enrdf_load_stackoverflow)
CN (1) CN1007542B (enrdf_load_stackoverflow)
CA (1) CA1248410A (enrdf_load_stackoverflow)
DE (1) DE3678538D1 (enrdf_load_stackoverflow)
IN (1) IN166532B (enrdf_load_stackoverflow)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5183393A (en) * 1992-02-10 1993-02-02 Schaffner Larey D Power limiter control for a variable displacement axial piston pump
US7797092B2 (en) * 2006-11-06 2010-09-14 Caterpillar Inc Method and system for controlling machine power
CN101865143B (zh) * 2010-07-08 2012-05-23 中国航天科技集团公司第六研究院第十一研究所 一种涡轮泵功率自动调节装置
CN111911381B (zh) * 2020-07-26 2022-12-06 中国航发贵州红林航空动力控制科技有限公司 一种带阻尼活塞的喷口压差活门机构
CN113266319B (zh) * 2021-07-01 2023-06-23 龙信阀业集团有限公司 一种适用于变压力气举举升工艺的气举阀

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2502546A (en) * 1947-03-28 1950-04-04 Denison Eng Co Hydraulic apparatus
US3067693A (en) * 1958-12-24 1962-12-11 United Aircraft Corp Control means for variable delivery pump
SE323286B (enrdf_load_stackoverflow) * 1967-12-04 1970-04-27 Sperry Rand Corp
US4072442A (en) * 1975-07-04 1978-02-07 Takeshi Horiuchi Variable delivery hydraulic pump

Also Published As

Publication number Publication date
CN86108529A (zh) 1987-06-17
CN1007542B (zh) 1990-04-11
JPH0819922B2 (ja) 1996-03-04
EP0226125A2 (en) 1987-06-24
DE3678538D1 (de) 1991-05-08
JPS62253980A (ja) 1987-11-05
EP0226125A3 (en) 1989-07-05
CA1248410A (en) 1989-01-10
IN166532B (enrdf_load_stackoverflow) 1990-05-26

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