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GB2049814A - Pumps for Hydraulic Systems - Google Patents

Pumps for Hydraulic Systems Download PDF

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Publication number
GB2049814A
GB2049814A GB8007388A GB8007388A GB2049814A GB 2049814 A GB2049814 A GB 2049814A GB 8007388 A GB8007388 A GB 8007388A GB 8007388 A GB8007388 A GB 8007388A GB 2049814 A GB2049814 A GB 2049814A
Authority
GB
United Kingdom
Prior art keywords
fluid
output
pressure
pump
valve
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB8007388A
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.)
Fiat Allis Europe SpA
Original Assignee
Fiat Allis Macchine Movimento Terra SpA
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 Fiat Allis Macchine Movimento Terra SpA filed Critical Fiat Allis Macchine Movimento Terra SpA
Publication of GB2049814A publication Critical patent/GB2049814A/en
Withdrawn legal-status Critical Current

Links

Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04CROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C14/00Control of, monitoring of, or safety arrangements for, machines, pumps or pumping installations
    • F04C14/24Control 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
    • F04C14/26Control 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
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04CROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C14/00Control of, monitoring of, or safety arrangements for, machines, pumps or pumping installations
    • F04C14/02Control 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

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Details And Applications Of Rotary Liquid Pumps (AREA)
  • Fluid-Pressure Circuits (AREA)
  • Rotary Pumps (AREA)

Abstract

A demand-responsive hydraulic- fluid pumping apparatus (1) for e.g. use in a vehicle, includes valving means (10, 11) to connect a pair of pumps (3, 4) either in a mutually parallel relationship or so that one pump (4) is by-passed while the other pump (3) alone feeds the load with fluid. The valving means operate in accordance with the output pressure in a conduit (6). The pumps may be of the externally-meshing gear type, Figures 2, 3 and 4 (not shown). <IMAGE>

Description

SPECIFICATION Fluid Pump for Hydraulic Circuits Background of the Invention This invention relates in general to vehicles, and, in particular, to hydraulic devices used to control operation of the vehicle.
More specifically, but without restriction to the particular use which is shown and described, this invention relates to a fluid pump for hydraulic circuits used to control operations of vehicles such as construction machinery or earth-moving machines and the like.
In general, the power output developed by the engine of a construction machinery vehicle must supply power to propel the vehicle, and to operate auxiliary working implements or tools such as a lifting arm for a loading bucket or grapple. For example, in Italian Patent No. 915,254, there is disclosed a system to divide and distribute the power developed from the vehicle engine by employing a hydraulic pump having two pump devices coupled for producing a flow of hydraulic fluid which is priority controlled by a fluid control circuit.Such use of a pair of pumps acting in tandem, permits full-flow operation during certain working conditions of the vehicle, below a predetermined threshold pressure value, but when the pressure required by the hydraulic circuit being supplied by the pump exceeds this threshold value, one of the pumps is bypassed to allow only the other pump to supply hydraulic fluid for operation. Accordingly, a reduction in the amount of fluid flow generated from the system is achieved and a corresponding increase in the pressure being supplied to the output which is desirable, for example, in the operation of earth moving equipment during a lifting or grabbing maneuver by a bucket or grapple. Although the tandemly operated pumps of Italian Patent No.
915,254 are intended to overcome such problems, a smooth and more rapid changeover from tandem to single jump operation in response to loading conditions is desired. In addition, prior tandemly operated pumps in the hydraulic system of a vehicle utilize complex and expensive hydraulic circuitry incapable of optimum efficiency of operation.
Summary of the Invention It is, therefore, an object of this invention to improve fluid pumping systms for hydraulic circuits.
Another object of this invention is to better control operations of tandemly operating fluid pump systems.
A further object of the invention is to effect rapid control of the operation of a pair of fluid pumps for effecting a difference in output of hydraulic fluid.
Still another object of the invention is to decrease the fluid flow output of fluid pumps in response to increased load requirements.
A still further object of this invention is to supply power to one pump device to the exclusion of another pump device in response to predetermined conditions.
These and other objects are attained in accordance with the present invention wherein there is provided a demand responsive hydraulic fluid pump, for use in vehicles and the like, which includes sequence valving means to operate a pair of pumps in a parallel relationship or, alternatively, to operate one pump to the exclusion of the other when it is desired to increase the output pressure in response to actual loading conditions. The invention permits the outputs of the pair of pumps to be combined when the driven circuit encounters a load below a predetermined threshold level, for a high volume lower pressure flow, but acts to bypass one of the pump devices upon the threshold level exceeding a predetermined value, thereby applying all of the fluid power derived from the vehicle engine to the remaining pump when a higher pressure, but lower volume, is necessary.
Description of the Drawings Further objects of the invention, together with an additional feature contributing thereto and advantages accruing therefrom, will be apparent from the following description of a preferred embodiment of the invention which is shown in the accompanying drawings with like reference numerals indicating corresponding parts throughout, wherein: Fig. 1 is a schematic view of the fluid pump of the invention; Fig. 2 is a perspective illustration of the fluid pump of Fig. 1 showing the hydraulic elements and pump devices thereof; Fig. 3 is a sectional side view of the fluid pump of Fig. 1;and Fig. 4 is a sectional view of the fluid pump of Fig. 3 taken along line IV-IV of Fig. 3.
Description of the Preferred Embodiment Referring now to Figs. 1 to 4, there is illustrated the demand responsive fluid pump, generally designated by reference number 1. The pump 1 includes a housing 2, forming the outer casing of the pump 1, in which the hydraulic control circuits of the pump are encased. As shown in Figs. 2-4, the housing 2 rotatabiy supports an input shaft 33 coupled to the output of a vehicle engine such that the shaft 33 supplies power to drive a first pump 3 and a second pump 4, such as conventional gear pumps. The first pump 3 includes a gear 3a mounted to the shaft 33 for rotation therewith. The gear 3a in turn drives a driven gear 3b. The second pump 4 includes a first gear 4a, secured to an extension 33a of the shaft 33 which extends coaxialiy therefrom, and engages with and drives a driven gear 4b.The first pump 3 is supplied with hydraulic fluid from a fluid reservoir 27 through an intake or inlet conduit 5. Rotation of the gears of the pump 3 produces an output flow of hydraulic fluid which is directed through an output conduit 6 to a conventional hydraulic distributor (not shown) which effects operation of the vehicle, for example, the loading bucket or grappel.
A second inlet conduit 7 supplies hydraulic fluid from the reservoir 27 to the second pump 4 for generating an output flow of hydraulic fluid through an outlet conduit 8. The outlet conduit 8 is in fluid communication with a cylindrical chamber 9 which is closed at its opposite ends by a first control valve 10 and by a second control valve 11. The first control valve 10 includes a valve shutter or gate 12 which is biased against a valve seat by the action of a spring 13, as shown in Figs. 1 and 4. A fluid conduit or passage 14 extends from the opposite side of the face of the valve gate 12 and extends into fluid communication with the output conduit 6 of the first pump 3. When the valve gate 12 is in a closed position, against the valve seat, fluid communication between the output conduit 8 of the second pump 4 and the output conduit 5 of the first pump 3 is terminated.
The second control valve assembly 11 includes a valve member 1 5 which is biased against its valve seat by a spring 16. The valve member 1 5 is provided with a sleeve-like control member 15a which is slideably positioned within a chamber 25. The chamber 25 is in fluid communication with the chamber 9, in which output conduit 8 is discharged, through a port 31 of relatively small diameter and extending through valve member 1 5.
A conduit or fluid passage 1 7 extends between the second inlet conduit 7 and a port provided adjacent to the valve control member 15a such that fluid communication between chamber 9 and the fluid passage 1 7 is blocked when valve member 1 5 is in a closed position as shown in Fig. 1. Upon opening of valve member 1 5, in a manner to be described, fluid communication between chamber 9 and the fluid passage 1 7 is established.
A fluid control conduit 18 is coupled in fluid communication between the conduit 14 and a pressure control chamber 1 9 of a pressure responsive piston 20, mounted for axial movement within the control chamber 19. A spring 30 biases an end 20a of the piston 20 into a first axial position, while the opposite end of the piston 20 is provided with a pressure responsive thrust surface 20b, against which the pressure of the fluid delivered by the control conduit 1 8 is directed.
The control chamber 1 9 further includes a first enlarged chamber zone or portion 21 and a second enlarged chamber zone or portion 22 axially spaced from one another adjacent the piston 20. The first enlarged zone is coupled by means of conduits 23 and 24 for fluid communication with the chamber 25 which is situated adjacent the valve member 1 5 of the second control valve 11. The second enlarged zone 22 of the control chamber 1 9 communicates by means of a discharge conduit 26 with the reservoir 27. The enlarged zones 21 and 22 of the control chamber 1 9 are placed in fluid communication with each other upon axial displacement of the piston 20 under the application of a pressure being applied to the thrust surface 20b and overcoming the bias of the spring 30.The piston 20 thus is axially displaced against the bias of spring 30 to move to its second axial position. Fluid communication is then established between the enlarged chambers or zones 21 and 22 upon the axial shifting of the piston 20 to its second position due to the pressure exerted on an intermediate portion 28, of the piston 20, which has a reduced cross section as best shown in Fig. 3. In operation of the invention, the two pumps 3 and 4 generate a first and second fluid output of a pressure dependent on the actual loading conditions required in operations. When the pressure of the fluid in the output conduit 6, which is coupled to a hydraulic fluid distributor, is below a predetermined threshold value, the pressure in the output conduit 8 is sufficient to maintain the valve gate 12 of the control valve 10 in an open position.
Thus, the fluid output produced by the pump 4 is combined with the fluid output of pump 3 through the coupling conduit 14. Under such conditions, the total fluid output of the demand responsive pump of the invention is equal to the sum of the fluid flow being discharged from the outputs of both pumps. During such parallel operation, through the action of the spring 16 of the pressure existing in the chamber 25, the valve member 1 5 of the control valve 11 is positioned to close fluid communication between the cylindrical chamber 9 and the fluid conduit 17.
The pressure in the chamber 25 is thereby maintained at a value equal to the pressure in the chamber 9 due to the presence of the port 31.
When the pressure in the output conduit 6, and consequently in conduit 14, exceeds the preestablished threshold value, the increased pressure is directed through conduit 18 to the pressure responsive thrust surface 20b of the piston 20. This pressure causes the axial movement of the piston or valve spool 20 against the action of the spring 30 to its second axial position. In such a situation, the reduced cross section of the portion 28 of the piston 20 establishes fluid communication between the two enlarged zones or chambers 21 and 22 of the piston 20. Accordingly, the regulation chamber 25 is caused to be in direct fluid communication with the reservoir 27 through the conduits 23, 24, and 26 which results in the pressure within the chamber 25 being reduced.
The pressure which is then applied to the valve member 15, in chamber 9, displaces the valve member 1 5 to a position placing the chamber 9 in fluid communication with the conduit 17, and therefore, with the inlet 7. In such a condition, the second pump 4, in effect, operates in a short circuited mode and absorbs substantially none of the power from the vehicle engine transmitted through the shaft 33. Such conditions further cause the valve gate 12 to close because of the reduced pressure within the chamber 9 and the biasing force of spring 13. The hydraulic distributor or circuit is consequently supplied only from the fluid output generated through conduit 6 by the first pump 3.In this manner, the pump 3 operates to provide a reduced quantity of hydraulic fluid as compared to parallel operation, but produces a higher output pressure and the power supplied by shaft 33 is applied solely to the pump 3 in view of the short circuited effect on pump 4.
While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.

Claims (11)

Claims
1. A fluid pump apparatus for hydraulic circuits comprising pump means including first and second pumps operatively coupled to a power source to produce first and second fluid outputs, respectively, first and second inlet means respectively coupling said first and second pumps to a supply of hydraulic fluid, first and second outlet means respectively coupled to said first and second pumps to receive said first and second outputs for delivery to a hydraulic fluid circuit, said second outlet means having a first fluid passage coupled in selective fluid communication with said first outlet means to permit the combination of said first and second outputs, said second output means having fluid control means coupled between said second pump and said first fluid passage to control the coupling of said second output to said first outlet means for combining said first and second outputs, said fluid control means being responsive to the pressure at said first output to couple said second output to said first outlet means when the pressure of said first output is below a predetermined threshold value and to terminate the supply of said second output to said first outlet means when the pressure of said first output exceeds said predetermined threshold valve, said fluid control means having a second fluid passage in selective fluid communication with said second inlet means, and said fluid control means being further responsive to the pressure of said first output to block fluid communication to said second inlet means through said second fluid passages when said first output pressure is below said predetermined threshold value and to establish fluid communication to said second inlet means through said second fluid passage when said first output pressure exceeds said predetermined threshold value thereby delivering substantially all of the power supplied by the power source to said first pump to increase said first output pressure.
2. The fluid pump apparatus for hydraulic circuits according to Claim 1 wherein said first and second pumps are gear pumps.
3. The fluid pump apparatus for hydraulic circuits according to Claim 2 wherein said fluid control means includes first and second valve means.
4. The fluid pump apparatus for hydraulic circuits according to Claim 3 wherein said first valve means is operatively positioned between the fluid output of said second pump and said first fluid passage.
5. The fluid pump apparatus for hydraulic circuits according to Claim 4 wherein said first valve means includes a valve gate mounted for movement from an open position permitting fluid communication to said first outlet means through said first fluid passage to a closed position blocking fluid communication to said first outlet means, and said valve gate being movable from said open position to said closed position when said first output pressure exceeds said predetermined threshold pressure.
6. The fluid pump apparatus for hydraulic circuits according to Claim 3 wherein said second valve means is operatively positioned between the fluid output of said second pump and said second fluid passage.
7. The pump apparatus for hydraulic circuits according to Claim 6 wherein said second valve means includes a valve member mounted for movement from a closed position blocking fluid communication to said second inlet means through said second fluid passage to an open position to establish fluid communication to said second inlet means through said second fluid passage, said valve member being movable from said closed position to said open position when said first output pressure exceeds said predetermined threshold pressure.
8. The fluid pump apparatus for hydraulic circuits according to Claim 3 wherein said fluid control means further includes a pressure responsive means in fluid communication with said first outlet means.
9. The fluid pump apparatus for hydraulic circuits according to Claim 8 wherein said pressure responsive means is responsive to said first output pressure and creates selective fluid communication between said second outlet means and the fluid supply.
10. The fluid pump apparatus for hydraulic circuits according to Claim 9 wherein said pressure responsive means provides fluid communication between said second fluid outlet means and the fluid supply upon said first pressure output exceeding said predetermined threshold level, said pressure responsive means blocking said fluid communication between said second outlet means and the fluid supply when said first output pressure is below said threshold level.
11. A fluid pump apparatus constructed and arranged substantially as hereinbefore described and as shown in the accompanying drawings.
GB8007388A 1979-03-07 1980-03-04 Pumps for Hydraulic Systems Withdrawn GB2049814A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
IT67480/79A IT1119682B (en) 1979-03-07 1979-03-07 AFLUID PUMP FOR HYDRAULIC CIRCUITS

Publications (1)

Publication Number Publication Date
GB2049814A true GB2049814A (en) 1980-12-31

Family

ID=11302760

Family Applications (1)

Application Number Title Priority Date Filing Date
GB8007388A Withdrawn GB2049814A (en) 1979-03-07 1980-03-04 Pumps for Hydraulic Systems

Country Status (7)

Country Link
JP (1) JPS55119993A (en)
BR (1) BR8001045A (en)
DE (1) DE3003108A1 (en)
FR (1) FR2450963A1 (en)
GB (1) GB2049814A (en)
IT (1) IT1119682B (en)
PL (1) PL222465A1 (en)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2140872A (en) * 1983-06-03 1984-12-05 Bosch Gmbh Robert Rotary positive-displacement fluid-machine
GB2214572A (en) * 1988-01-29 1989-09-06 Toshiba Kk Compressing apparatus with variable capacity range and capacity control
GB2286017A (en) * 1994-01-21 1995-08-02 Concentric Pumps Ltd Improvements relating to pumps
CN104214090A (en) * 2014-08-08 2014-12-17 宁波雪隆王液压科技有限公司 An integral structure of a gear pump and a jet flow valve
DE102019132783A1 (en) * 2019-12-03 2020-10-08 Audi Ag Compressor arrangement for a drive of a motor vehicle and motor vehicle with a compressor arrangement

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3210759A1 (en) * 1981-09-17 1983-10-06 Walter Schopf Pump combination with flow control device
JPS6123485U (en) * 1984-07-18 1986-02-12 東京部品工業株式会社 Gear pump with metering circuit
JP2009062970A (en) * 2007-08-09 2009-03-26 Toyota Industries Corp Variable displacement type gear pump
CN104806518A (en) * 2015-03-31 2015-07-29 徐工集团工程机械股份有限公司道路机械分公司 Electronic control converging pump achieving variable displacement of gear pumps
JP6771338B2 (en) * 2016-08-26 2020-10-21 三菱パワー株式会社 Pump system and its operation method and power plant

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1004798A (en) * 1947-05-14 1952-04-02 Snecma Installation of pressurized fluid distribution at various flow rates
DE1040904B (en) * 1952-05-21 1958-10-09 Borg Warner Hydraulic pump system
US3067689A (en) * 1958-10-06 1962-12-11 Gen Motors Corp Variable capacity fluid supply
US3361068A (en) * 1966-08-18 1968-01-02 Allis Chalmers Mfg Co Double hydraulic pump with built-in unloading valve
GB1331850A (en) * 1970-11-17 1973-09-26 Fiat Spa Self regulating gear pump
JPS5124729B2 (en) * 1972-07-11 1976-07-26

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2140872A (en) * 1983-06-03 1984-12-05 Bosch Gmbh Robert Rotary positive-displacement fluid-machine
GB2214572A (en) * 1988-01-29 1989-09-06 Toshiba Kk Compressing apparatus with variable capacity range and capacity control
US5013217A (en) * 1988-01-29 1991-05-07 Kabushiki Kaisha Toshiba Compressing apparatus with extended variable capacity range and capacity control method thereof
GB2214572B (en) * 1988-01-29 1992-06-24 Toshiba Kk Compressing apparatus with variable capacity range and capacity control method thereof
GB2286017A (en) * 1994-01-21 1995-08-02 Concentric Pumps Ltd Improvements relating to pumps
CN104214090A (en) * 2014-08-08 2014-12-17 宁波雪隆王液压科技有限公司 An integral structure of a gear pump and a jet flow valve
DE102019132783A1 (en) * 2019-12-03 2020-10-08 Audi Ag Compressor arrangement for a drive of a motor vehicle and motor vehicle with a compressor arrangement

Also Published As

Publication number Publication date
DE3003108A1 (en) 1980-09-11
BR8001045A (en) 1980-10-29
PL222465A1 (en) 1981-01-30
JPS55119993A (en) 1980-09-16
IT7967480A0 (en) 1979-03-07
IT1119682B (en) 1986-03-10
JPS6220397B2 (en) 1987-05-07
FR2450963A1 (en) 1980-10-03

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WAP Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1)