EP0016289A1 - Verdrängerpumpen-Systeme - Google Patents

Verdrängerpumpen-Systeme Download PDF

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Publication number
EP0016289A1
EP0016289A1 EP19790302783 EP79302783A EP0016289A1 EP 0016289 A1 EP0016289 A1 EP 0016289A1 EP 19790302783 EP19790302783 EP 19790302783 EP 79302783 A EP79302783 A EP 79302783A EP 0016289 A1 EP0016289 A1 EP 0016289A1
Authority
EP
European Patent Office
Prior art keywords
valve
valve member
delivery
passage
fluid
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.)
Granted
Application number
EP19790302783
Other languages
English (en)
French (fr)
Other versions
EP0016289B1 (de
Inventor
Ian Trevor Bristow
Nigel James Petts
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.)
Hobourn Eaton Ltd
Original Assignee
Hobourn Eaton Ltd
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 Hobourn Eaton Ltd filed Critical Hobourn Eaton Ltd
Publication of EP0016289A1 publication Critical patent/EP0016289A1/de
Application granted granted Critical
Publication of EP0016289B1 publication Critical patent/EP0016289B1/de
Expired 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
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C14/00—Control of, monitoring of, or safety arrangements for, machines, pumps or pumping installations
    • F04C14/24—Control of, monitoring of, or safety arrangements for, machines, pumps or pumping installations characterised by using valves controlling pressure or flow rate, e.g. discharge valves or unloading valves
    • F04C14/26—Control of, monitoring of, or safety arrangements for, machines, pumps or pumping installations characterised by using valves controlling pressure or flow rate, e.g. discharge valves or unloading valves using bypass channels
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C14/00—Control of, monitoring of, or safety arrangements for, machines, pumps or pumping installations
    • F04C14/02—Control of, monitoring of, or safety arrangements for, machines, pumps or pumping installations specially adapted for several machines or pumps connected in series or in parallel

Definitions

  • This invention relates to positive displacement pump systems.
  • a positive displacement pump system having a first pressure fluid delivery passage connected to a main discharge passage containing a discharge orifice, a second pressure fluid delivery passage connected to the first delivery passage under the control of a valve
  • a valve comprising a.valve member slidably mounted in a. valve bore, said valve member having applied to it a force derived from the pressure drop across said orifice and operating in response to an increase of said pressure drop above a predetermined value to move the valve member to cause fluid from the first and second delivery passages to be by-passed through an overspill port as the said pressure drop increases, and means for superimposing on the valve member an additional force which is derived from the delivery pressure in one of said delivery passages and which operates in the same sense as the first said force.
  • said additional force varies as the square of the fluid delivery pressure from which it is derived
  • the pressure fluid from the second delivery passage flows through an axial duct extending through a part of the length of the valve member and opening through an axially facing port in the valve member to join the flow through the first delivery passage, the reaction force of the flow emerging from said port constituting said additional force.
  • the end portion of the axial duct terminating in said port is of convergent cross-section thereby to form a nozzle.
  • said one end portion of the valve has a reduced diameter extension which forms with the valve bore an annular restriction between the first fluid delivery passage and the main discharge passage, the pressure upstream of the orifice being applied to the annu,ar area of the valve member formed at the location of the reduction of diameter, and the pressure of the fluid at the upstream end of the annular restriction is applied to the end face of the reduced diameter extension thereby to provide said additional force.
  • the form of positive displacement pumping mechanism indicated generally at 10 is not material to the invention but the pump is required to deliver pressure fluid to first and second delivery passages 11, 12 which are in communication with each other under the control of a control valve 13.
  • the combined flow from passages 11 and 12, less any which is surplus to the immediate requirements of-the external circuit and which is directed to an overspill port 14 in the valve and thence to a fluid reservoir or the pump inlet for recirculation, is delivered to the external circuit through a main discharge passage 15 in which is mounted a screwed plug 16 providing a discharge control orifice 17.
  • the orifice is of accurately predetermined diameter according to the required fluid delivery, and the pressure drop across the orifice is applied to the valve 13 to maintain the flow through the orifice substantially constant.
  • a pump may supply pressure servo-fluid, for example to the open-centre servo valve of a servo- assisted vehicle steering mechanism.
  • the valve 13 comprises a valve member 20 slidably mounted in a valve bore 21.
  • the upper end of the valve bore has screwed into it a plug 22 carrying a spring-loaded ball relief valve 23 through which fluid under excess pressure in a chamber 24 formed at the upper end of the bore can be discharged into the encompassing fluid reservoir 18.
  • Chamber 24 contains a spring 24a which urges the valve member 20 downward into abutment with an annular shoulder 25 at the other end of the valve bore.
  • Chamber 24 communicates through a drilling 26 with the main discharge passage 15 at a location downstream of the orifice 17.
  • the lower end of the valve bore opens through an aperture bounded by the shoulder 25 with a smaller- diameter extension 27 of the valve bore, placing the first delivery passage 11 in permanently open communication with the main discharge passage 15 so that the pressure at the upstream side of the orifice 17 is applied to the lower end of the valve member.
  • the pressures at the upstream and downstream sides of the orifice 17 are thus respectively applied against the lower and upper ends of the valve member.
  • the upper end portion 28 of the valve member blocks off communication between the secondary delivery passage 12 and the spring chamber 24. From below the portion 28 the valve member has a central axial bore 29 the lower end portion of which has a convergent cress- section forming a nozzle 30 opening to the bore extension 27. Below portion 28 the valve member has a reduced-diameter port forming about it an annular space 32 to which the second delivery passage opens, and two sets of ports 33, 34 in the wall of the , reduced-diameter part of the valve member place the central bore 29 in communication with the second delivery passage 12 via space 32.
  • the additional force is derived from the reaction, acting in an upward direction on the valve member, of the kinetic energy of the jet issuing downward from the nozzle 30.
  • the additional force is thus a function of the square of the speed of the flow through nozzle 30 and hence of the quantity of fluid delivered to the second delivery passage 12.
  • the valve member is also moved a greater amount against the spring force than would otherwise be the case for a given increase in pump speed and increases the rate of opening of the overspill port.
  • the requirement for reduced flow at low pressure at high vehicle speeds exists in some cases, and the delivery characteristic of the pump shown is thus capable of being matched to the steering force requirement.
  • the control valve shown in Figure 2 is constructed in a different manner and operates somewhat differently from that in Figure 1.
  • the first and second delivery passages 11, 12 are separately connected, under overspill conditions, to overspill porting.
  • the valve member has an additional reduced-diameter portion forming a second annular space 40 separated from the annular space 32 by a land 41.
  • An auxiliary overspill port 42 opens to the annular space 40 and communicates through the valve body with the overspill passage leading from the overspill port 14.
  • a land 44 at the lower end of the annular space 40 cuts off communication between the first delivery passage 11 and overspill port 14 when the valve member is in its lowermost position as shown in Figure 2.
  • the valve member has a reduced-diameter extension sleeve 46 projecting below the shoulder 25 and the lower end of the extension is shown resting on the bottom of the extended valve bore and holding the land 44 away from the shoulder 25.
  • the first delivery port 11 and main discharge passage 15 are spaced from each other lengthwise of the valve bore, and an annular gap between the sleeve 46 and the surrounding part of the valve bore forms a flow restriction 48 between passages 11 and 15.
  • a plug 4.9 having a venting passage 50 is secured in the lower end of the sleeve 46, and light spring 51 rests against the plug and urges a ball 52 against a seating at the lower end of the axial bore of the valve member to form a non-return valve, which permits pressure fluid to flow from the second delivery passage through an axial bore and through radial ports 54 in the sleeve to the main discharge passage 15, but not in the reverse direction.
  • the Bernoulli effect acts to apply a strong force to the valve member tending to close the communication with the overspill ports when the area of communication is small.
  • This force is offset in the construction of Figure 2 by an additional force resulting from the pressure of the fluid at the upstream End of the annular restriction 48 acting on the lower end of the sleeve and plug 49. This pressure is higher than it would be if the sleeve and annular restriction were not present.
  • the pump speed continues to increase the valve member is moved upward.by the tendency for the pressure drop across the discharge orifice 17 to increase, and the additional loading acting on the sleeve 46 and plug 49 to lift the valve member increases according to a square law in relation to increases in pump speed.
  • the port 14 is simply a port in the sidewall of the bore and is of smaller area than the overspill port 42, and since a given upward movement of the valve member will result in a much larger increase in the area of the annular gap between the land 40 and the annular edge 50 leading to the annular space 40 and thence to the overspill port 42, it follows that the proportion of the delivery from passage 12 flowing to the overspill increases more rapidly than that of the delivery from passage 11 as the valve member moves upward, so that eventually the whole of the delivery from passage 12 is passed to the overspill. The whole of the needs of the external circuit are then supplied from passage 11 whilst a proportion of the delivery from passage 11 is also being passed to overspill through the port 14.
  • a further advantage of the construction shown in Figure 2 arises in relation to leakage between the delivery passage 12 and the spring chamber 24 past the upper end portion 28 of the valve member.
  • the pressure difference between passage 12 and the spring chamber is small and thus leakage past the end portion 28 into the spring chamber is small.
  • the pressure in the spring chamber remains up to its proper'value and the valve is held in its closed position until the pressure conditions predetermined by the spring loading and the discharge orifice to result in opening the valve are attained.
  • FIG. 3 a modified version of the arrangement of Figure 2 is shown.
  • the second delivery passage 12 is connected to the first delivery passage 11 through a passage in the valve body instead of through the hollow valve member, and the port 12a of passage 12 serves only for overspill fluid.
  • the valve member is shown in a position in which there is partial overspill of the fluid delivered through passage 12.
  • the connecting passage is indicated diagrammatically at 38 and has disposed in it a spring-loaded non-return valve 39 which permits fluid to flow from passage 12 to passage 11 but not in the reverse direction, so that when the valve member reaches a position in which the whole of the flow passage 12 is being passed to the overspill ports 14, 42 via the annular space 40, valve 39 closes to isolate passages 12 and 11 from each other.
  • Valve 44 thus replaces the relief valve 23 in the arrangement of Figure 2 but operates in a similar way, by venting the spring chamber to the overspill port 14 to cause the valve member to move upward and permit an increased flow of fluid from passage 12 or passages 12 and 11 through the overspill ports 42 and 14, thus reducing substantially the amount of fluid delivered into the main discharge passage 15.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Details Of Reciprocating Pumps (AREA)
  • Safety Valves (AREA)
  • Details And Applications Of Rotary Liquid Pumps (AREA)
EP19790302783 1978-12-13 1979-12-04 Verdrängerpumpen-Systeme Expired EP0016289B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB7848269 1978-12-13
GB4826978 1978-12-13

Publications (2)

Publication Number Publication Date
EP0016289A1 true EP0016289A1 (de) 1980-10-01
EP0016289B1 EP0016289B1 (de) 1985-02-06

Family

ID=10501691

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19790302783 Expired EP0016289B1 (de) 1978-12-13 1979-12-04 Verdrängerpumpen-Systeme

Country Status (4)

Country Link
EP (1) EP0016289B1 (de)
JP (1) JPS5582870A (de)
DE (1) DE2967381D1 (de)
GB (1) GB2038932B (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2238355A (en) * 1989-10-21 1991-05-29 Ultra Hydraulics Ltd An hydraulic pump

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2878753A (en) * 1954-03-17 1959-03-24 American Brake Shoe Co Vane pump
DE972842C (de) * 1953-12-08 1959-10-08 Rickmeier Pumpen Regeleinrichtung fuer eine Foerderstufe oder mehrere parallel geschaltete Foerderstufen von Zahnradpumpen zum Foerdern von Fluessigkeit unter Druck
FR1246014A (fr) * 1959-01-26 1960-11-10 Webster Electric Co Inc Dispositif à deux pompes et à obturateurs de contrôle

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5020242B1 (de) * 1970-08-18 1975-07-14
JPS5034250A (de) * 1973-07-26 1975-04-02
JPS5199131A (en) * 1975-02-26 1976-09-01 Tsnii Kuropuchatobu Mazunoi Pu Boshokusenino ringuresuseiboki

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE972842C (de) * 1953-12-08 1959-10-08 Rickmeier Pumpen Regeleinrichtung fuer eine Foerderstufe oder mehrere parallel geschaltete Foerderstufen von Zahnradpumpen zum Foerdern von Fluessigkeit unter Druck
US2878753A (en) * 1954-03-17 1959-03-24 American Brake Shoe Co Vane pump
FR1246014A (fr) * 1959-01-26 1960-11-10 Webster Electric Co Inc Dispositif à deux pompes et à obturateurs de contrôle

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2238355A (en) * 1989-10-21 1991-05-29 Ultra Hydraulics Ltd An hydraulic pump
GB2238355B (en) * 1989-10-21 1993-08-25 Ultra Hydraulics Ltd A gear pump

Also Published As

Publication number Publication date
EP0016289B1 (de) 1985-02-06
DE2967381D1 (en) 1985-03-21
JPS5582870A (en) 1980-06-21
GB2038932A (en) 1980-07-30
GB2038932B (en) 1982-10-27

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