GB2276673A - Hydraulic systems - Google Patents

Hydraulic systems Download PDF

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Publication number
GB2276673A
GB2276673A GB9306906A GB9306906A GB2276673A GB 2276673 A GB2276673 A GB 2276673A GB 9306906 A GB9306906 A GB 9306906A GB 9306906 A GB9306906 A GB 9306906A GB 2276673 A GB2276673 A GB 2276673A
Authority
GB
United Kingdom
Prior art keywords
fluid
pumps
reservoir
pressure
hydraulic system
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
GB9306906A
Other versions
GB9306906D0 (en
GB2276673B (en
Inventor
Anthony James Duthie
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.)
JOHNSTON ENG Ltd
Original Assignee
JOHNSTON ENG 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 JOHNSTON ENG Ltd filed Critical JOHNSTON ENG Ltd
Priority to GB9306906A priority Critical patent/GB2276673B/en
Publication of GB9306906D0 publication Critical patent/GB9306906D0/en
Priority to EP94302142A priority patent/EP0618371B1/en
Priority to DE69410330T priority patent/DE69410330T2/en
Priority to US08/220,221 priority patent/US5477882A/en
Publication of GB2276673A publication Critical patent/GB2276673A/en
Application granted granted Critical
Publication of GB2276673B publication Critical patent/GB2276673B/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

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
    • F15B11/16—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors
    • F15B11/17—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors using two or more 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
    • F15B1/00—Installations or systems with accumulators; Supply reservoir or sump assemblies
    • F15B1/26—Supply reservoir or sump assemblies
    • 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
    • F15B2211/20576—Systems with pumps with multiple 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
    • F15B2211/40—Flow control
    • F15B2211/405—Flow control characterised by the type of flow control means or valve
    • F15B2211/40507—Flow control characterised by the type of flow control means or valve with constant throttles or orifices
    • 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
    • F15B2211/40—Flow control
    • F15B2211/415—Flow control characterised by the connections of the flow control means in the circuit
    • F15B2211/41554—Flow control characterised by the connections of the flow control means in the circuit being connected to a return line 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
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/61—Secondary circuits
    • 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
    • F15B2211/71—Multiple output members, e.g. multiple hydraulic motors or cylinders
    • 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
    • F15B2211/80—Other types of control related to particular problems or conditions
    • F15B2211/885—Control specific to the type of fluid, e.g. specific to magnetorheological fluid
    • 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
    • Y10T137/85978—With pump
    • Y10T137/86035—Combined with fluid receiver
    • Y10T137/86059—Hydraulic power unit
    • 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
    • Y10T137/85978—With pump
    • Y10T137/86131—Plural
    • Y10T137/86163—Parallel

Abstract

A hydraulic system 10 provides a positive supply of hydraulic fluid at a controlled pressure to plurality of pumps. The system comprises a fluid reservoir 15 having outlet means to supply fluid to an auxiliary pump 30. A pressure chamber 16 communicates with a reservoir 15 and has outlet means to supply fluid to a plurality of working pumps 11, 12, 13. An inlet manifold 18 is provided for receiving fluid returned from the working and auxiliary pumps. <IMAGE>

Description

2276673 IMPROVEMENTS IN HYDRAULIC SYSTEMS The invention relates to
improvements in hydraulic systems and in particular to a system for providing a positive flow of hydraulic fluid to a number of open-loop hydraulic pumps.
Many mobile machines, such as road sweeping machines, utilise hydraulic pumps for various duties. These duties can include propelling the vehicle via a hydrostatic transmission system, driving an exhauster fan with a hydraulic motor to generate the suction source for collecting debris, hydraulic drives for other apparatus such as brushes, water pumps, cylindrical actuators and so on. A feature often required of such mobile machines is that they are expected to work on various climatic conditions, from the hottest day in summer to the coldest day in winter without any adjustments having to be made.
Where the hydraulic pumps are "open-loop" pumps,, the pumps usually draw their oil directly from a reservoir which is used to pressurise the working circuit with the hydraulic fluid being returned to the reservoir via some sort of filter prior to recirculation. To serve the pump with fluid, the suction line, associated connections, isolation valves and so on need to be of suitably large proportions to ensure that cavitation does not occur in cold conditions or on initial start-up at the beginning of a working shift when the fluid is cold and naturally more viscous. This has the disadvantage that the pipework and associated equipment are generally larger than needed once the system has warmed up, which means an increase in weight of the apparatus and the cost. The positioning of the reservoir relative to the pumps is also fairly critical to ensure that positive pressure is provided to the pumps.
It is therefore an object of the present invention to provide a hydraulic system which provides a positive supply of fluid at a controlled pressure which is sensitive to the viscosity of the oil and which overcomes these disadvantages.
According to the invention there is therefore provided a hydraulic system for providing a positive supply of hydraulic fluid at a controlled pressure to a plurality of pumps, comprising a fluid reservoir; said fluid reservoir having outlet means to supply fluid to an auxiliary pump; a pressure chamber communicating with said reservoir; said pressure chamber having outlet means to supply fluid to a plurality of working pumps, and inlet means for receiving fluid returned from the working and auxiliary pumps.
A preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:- Fig. 1 is a schematic representation of a hydraulic system according to the invention; and Fig. 2 is a graphical representation of the pressure characteristics of the invention of Fig. 1.
Referring to Fig. 1, there is provided a hydraulic system 10 comprising three open-loop hydraulic pumps 11, 12, 13. The three pumps 11, 12, 13 serve respectively working circuits lla, 12a, 13a which can include appartus and drives having any functions required.
The pumps 11. 12r 13 are supplied with hydraulic fluid 14 which is stored in a central reservoir 15. Integrated into the central reservoir is a pressure canister 16 which is in a generally cylindrical shape and has an open flange 17 at one end thereof. Bolted onto the open flange 17 is a ceiling manifold 18 which il provides connections 19 for the return lines 20 from the working circuits lla, 12a, 13a.
Inside the pressure canister 16 is a fine micronic filter 21 which filters the fluid returning from the working circuits.
At the opposite end of the canister 16 to the manifold 18 are provided means 22 for connecting the inlet of the pumps 11, 12, 13.
The pressure canister draws hydraulic fluid direct from the reservoir 15 via orifice 25. There is also a relief valve 26 which allows the pressure canister 16 to vent to the main reservoir at a certain preset pressure.
The system 10 also has an auxiliary pump 30, which may also supply a working circuit 30a. Pump 30 draws it working fluid directly from a main reservoir 15, rather than the pressure canister 16. but returns it to the pressure canister 16. The result is that pumps 11, 12, 13 are provided with a "boosted" inlet flow from the canister 16. The boost pressure created within the canister 16 is generated by the condition where the returning fluid to the canister 16 is of a greater volume than the output flow to the pump 11, 12, 13. The relief valve, set for example at one bar. enables any excess oil to be vented directly to the reservoir over the preset pressure.
The orifice 25 helps to provide thermal control related to oil temperature or viscosity. For instance when the oil is cold and more viscose, the boost pressure is at the one bar setting as the relief valves would be active. As the fluid warms up and becomes less viscose. the boost pressure will drop due to the relief valve closing with the orifice 25 solely providing the pressure influence. With an auxiliary flow of approximately 35 litres per minute, the orifice would normally be 5mm in diameter.
The hydraulic pressure control system 10 can thus compensate for pressure drop characteristics that can result from viscosity changes in the connections or pipework to the pumps, i.e. higher viscosity results in a higher boost pressure, whereas lower viscosity results in a lower boost pressure. This feature can be applied to a system where the pressure criteria of the actual pumps inlet port would be constant, regardless of what the viscosity index of the fluid is.
The orifice outlet 25 being submerced within the fluid in a main reservoir 15 also provides another function in that it allows the booster pumps during their initial priming process on first start-up to draw oil from the reservoir via this orifice.
Fig. 2 shows the boost pressure characteristics generated by the combination of the orifice and relief valve 26 with the peak value W being the relief valve setting value.
The invention therefore provides a system where a positive supply of hydraulic fluid can always be fed to the main circuit pumps at a controlled pressure; the system is sensitive to the viscosity of oil; the pipework proportions can be smaller due to a positive pressure influence, thus saving weight and cost; the positioning of the reservoir relative to the booster pumps is less critical with regard to being above or below the pumps, or its distance from them due to the possibility of a positive pressure influence.
P v

Claims (6)

CLAIMS:
1. A hydraulic system for providing a positive supply of hydraulic fluid at a controlled pressure to a plurality of pumps, comprising a fluid reservoir; said fluid reservoir having outlet means to supply fluid to an auxiliary pump; a pressure chamber communicating with said reservoir; said pressure chamber having outlet means to supply fluid to a plurality of working pumps, and inlet means for receiving fluid returned from the working and auxiliary pumps.
2. A hydraulic system as claimed in claim 1 in which the pressure chamber communicates with said reservoir by means of an orifice.
3. A hydraulic system as claimed in claim 1 or claim 2 in which the pressure chamber further comprises a relief valve, set at a predetermined pressure setting, allowing the chamber to vent fluid above the predetermined pressure to the reservoir.
4. A hydraulic system as claimed in any one of the preceding claims further comprising a plurality of open-loop working pumps connected to the outlet and inlet means of the pressure chamber.
5. A hydraulic system as claimed in any one of the preceding claims further comprising an open-loop auxiliary pump connected to the outlet means of the fluid reservoir and the inlet means of the pressure chamber.
6. A hydraulic system as hereinbefore described with reference to and as shown in the accompanying drawings.
GB9306906A 1993-04-02 1993-04-02 Improvements in hydraulic systems Expired - Fee Related GB2276673B (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
GB9306906A GB2276673B (en) 1993-04-02 1993-04-02 Improvements in hydraulic systems
EP94302142A EP0618371B1 (en) 1993-04-02 1994-03-24 Hydraulic system
DE69410330T DE69410330T2 (en) 1993-04-02 1994-03-24 Hydraulic system
US08/220,221 US5477882A (en) 1993-04-02 1994-03-30 Hydraulic systems

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB9306906A GB2276673B (en) 1993-04-02 1993-04-02 Improvements in hydraulic systems

Publications (3)

Publication Number Publication Date
GB9306906D0 GB9306906D0 (en) 1993-05-26
GB2276673A true GB2276673A (en) 1994-10-05
GB2276673B GB2276673B (en) 1996-09-11

Family

ID=10733231

Family Applications (1)

Application Number Title Priority Date Filing Date
GB9306906A Expired - Fee Related GB2276673B (en) 1993-04-02 1993-04-02 Improvements in hydraulic systems

Country Status (4)

Country Link
US (1) US5477882A (en)
EP (1) EP0618371B1 (en)
DE (1) DE69410330T2 (en)
GB (1) GB2276673B (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2343920B (en) * 1998-11-17 2003-04-23 Luk Fahrzeug Hydraulik Pumping System
WO2014037577A1 (en) * 2012-09-10 2014-03-13 Trw Automotive Gmbh Fluid container, in particular hydraulic reservoir for a motor-pump unit

Families Citing this family (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5724812A (en) * 1996-02-16 1998-03-10 Baker; William E. Variable displacement apparatus and method of using same
US5943861A (en) * 1997-12-15 1999-08-31 General Motors Corporation Hydraulic system for motor vehicle
US6758231B1 (en) * 1998-06-17 2004-07-06 Light Wave Ltd. Redundant array control system for water rides
US6116006A (en) * 1999-05-27 2000-09-12 Deere & Company Hydraulic system for a detachable implement
US6832969B2 (en) * 2001-04-20 2004-12-21 Trw Inc. Hydraulic power steering system with reservoir and method of operating same
DE10244383B4 (en) * 2002-09-24 2008-04-17 Zf Lenksysteme Gmbh oilcontainer
US20040067194A1 (en) * 2002-10-04 2004-04-08 Awad Hanna Albert Torch in water will slit water into oxygen and hydrogen
US20040156779A1 (en) * 2003-02-11 2004-08-12 Awad Hanna Albert Way to split oxygen and hydrogen of water with zero energy input
DE10326887A1 (en) * 2003-06-14 2004-12-30 Daimlerchrysler Ag Multi-stage oil pump system
US7302798B2 (en) * 2004-07-07 2007-12-04 Toyoda Koki Kabushiki Kaisha Hydraulic system, reservoir and pump suction enhancer for motor vehicle
US9599127B2 (en) * 2009-03-10 2017-03-21 Deere & Company Hydraulic circuit supply system
US8444935B2 (en) * 2009-06-12 2013-05-21 Bose Corporation Multiple-specimen device testing with particle measurement
US8956130B2 (en) * 2009-12-23 2015-02-17 Pentair Flow Technologies, Llc Redundant sump pump system
KR101463489B1 (en) * 2010-05-31 2014-11-19 가부시키가이샤 고마쓰 세이사쿠쇼 Hydraulic oil tank, hydraulic oil tank manufacturing method, and construction vehicle equipped with hydraulic oil tank
EP3757401A1 (en) * 2019-06-27 2020-12-30 Aber Hydraulics, S.A. Flange for attaching a valve for tank oil return, operation and uses thereof

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2830668A (en) * 1956-11-01 1958-04-15 United Aircraft Corp Hydraulic system for an aeronautical propeller
US3130548A (en) * 1961-12-22 1964-04-28 Clark Equipment Co Pressurized sump
US3331445A (en) * 1965-12-14 1967-07-18 Daniel P Currie Means for increased pitch change rate
DE2711137C2 (en) * 1977-03-15 1985-01-03 Klöckner-Humboldt-Deutz AG, 5000 Köln Hydraulic system with a reservoir for the liquid pressure medium
DE2733523A1 (en) * 1977-07-25 1979-02-01 Int Harvester Co HYDRAULIC SYSTEM, IN PARTICULAR FOR AGRICULTURAL OR CONSTRUCTION USE TRACTOR OR WORKING MACHINERY
US4531368A (en) * 1983-12-19 1985-07-30 Deere & Company Reservoir for a multi-pump hydraulic system
JPS6232098U (en) * 1985-08-13 1987-02-25
GB8624953D0 (en) * 1986-10-17 1986-11-19 Action Pumping Services Ltd Hydro-pneumatic pumpsets

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2343920B (en) * 1998-11-17 2003-04-23 Luk Fahrzeug Hydraulik Pumping System
DE19952144B4 (en) * 1998-11-17 2014-01-16 Ixetic Bad Homburg Gmbh Pressure medium conveying device with a pump device above a pressure medium reservoir with connection to the associated pressure line
WO2014037577A1 (en) * 2012-09-10 2014-03-13 Trw Automotive Gmbh Fluid container, in particular hydraulic reservoir for a motor-pump unit
CN104619995A (en) * 2012-09-10 2015-05-13 Trw汽车股份有限公司 Fluid container, in particular hydraulic reservoir for a motor-pump unit

Also Published As

Publication number Publication date
DE69410330T2 (en) 1998-09-17
DE69410330D1 (en) 1998-06-25
US5477882A (en) 1995-12-26
EP0618371A3 (en) 1995-03-08
GB9306906D0 (en) 1993-05-26
EP0618371A2 (en) 1994-10-05
EP0618371B1 (en) 1998-05-20
GB2276673B (en) 1996-09-11

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Legal Events

Date Code Title Description
PCNP Patent ceased through non-payment of renewal fee

Effective date: 20020402