EP0607604A1 - Hydraulic system for a vehicle - Google Patents

Hydraulic system for a vehicle Download PDF

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Publication number
EP0607604A1
EP0607604A1 EP93120792A EP93120792A EP0607604A1 EP 0607604 A1 EP0607604 A1 EP 0607604A1 EP 93120792 A EP93120792 A EP 93120792A EP 93120792 A EP93120792 A EP 93120792A EP 0607604 A1 EP0607604 A1 EP 0607604A1
Authority
EP
European Patent Office
Prior art keywords
pump
vehicle
hydraulic system
liquid
line
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
EP93120792A
Other languages
German (de)
French (fr)
Other versions
EP0607604B1 (en
Inventor
Andrew Thomas Benko
James Allen Swartzendruber
John Louis Bocksnick
Gary W. Clark
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.)
Deere and Co
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Deere and Co
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Publication date
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Publication of EP0607604A1 publication Critical patent/EP0607604A1/en
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Publication of EP0607604B1 publication Critical patent/EP0607604B1/en
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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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/205—Systems with pumps
    • F15B2211/2053—Type of pump
    • F15B2211/20538—Type of pump constant capacity
    • 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
    • F15B2211/2053—Type of pump
    • F15B2211/20546—Type of pump variable capacity
    • 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
    • F15B2211/30—Directional control
    • F15B2211/305—Directional control characterised by the type of valves
    • F15B2211/3056—Assemblies of multiple valves
    • F15B2211/30585—Assemblies of multiple valves having a single valve for multiple output members
    • 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
    • F15B2211/30—Directional control
    • F15B2211/31—Directional control characterised by the positions of the valve element
    • F15B2211/3105—Neutral or centre positions
    • F15B2211/3116—Neutral or centre positions the pump port being open in the centre position, e.g. so-called open centre
    • 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
    • F15B2211/40515—Flow control characterised by the type of flow control means or valve with variable 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
    • F15B2211/42—Flow control characterised by the type of actuation
    • F15B2211/426—Flow control characterised by the type of actuation electrically or electronically
    • 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
    • F15B2211/45—Control of bleed-off flow, e.g. control of bypass flow 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
    • F15B2211/40—Flow control
    • F15B2211/455—Control of flow in the feed line, i.e. meter-in control
    • 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
    • F15B2211/62—Cooling or heating 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
    • F15B2211/7107—Multiple output members, e.g. multiple hydraulic motors or cylinders the output members being mechanically linked
    • 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
    • F15B2211/7114—Multiple output members, e.g. multiple hydraulic motors or cylinders with direct connection between the chambers of different actuators
    • F15B2211/7121—Multiple output members, e.g. multiple hydraulic motors or cylinders with direct connection between the chambers of different actuators the chambers being connected in series
    • 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
    • F15B2211/7114—Multiple output members, e.g. multiple hydraulic motors or cylinders with direct connection between the chambers of different actuators
    • F15B2211/7128—Multiple output members, e.g. multiple hydraulic motors or cylinders with direct connection between the chambers of different actuators the chambers being connected in parallel

Definitions

  • the invention relates to a hydraulic system for a vehicle with a collection container, a first and a second pump, a suction line connecting the collection container to the first pump, a first propellant connected to the first pump for driving a first vehicle component, a second with the second pump connected propellant for driving a second vehicle component and a return line for the second pump.
  • This hydraulic system (US-A-5 069 037) is designed for a lawn tractor that is equipped with a sickle mower between its front and rear wheels.
  • the first pump is part of a hydrostatic drive for the rear wheels, while the second pump is part of an auxiliary power steering system and is used to pressurize lifting cylinders.
  • Both pumps are arranged in the area of a rear vehicle transmission, the sump of which also serves as a collecting tank for the hydraulic system, and have their own hydraulic circuit with a common suction line.
  • the pumps are thus connected in parallel to each other so that each pump draws in the required liquid separately. This requires a relatively large amount of liquid, even if the pumps have different capacities.
  • a branch line connected to the outlet of the first propellant is provided with a first branch connected to the collecting container and a second branch connected to the second pump, the return line being connected to the suction line.
  • the branch line is connected downstream of the first propellant, and liquid emerging from this first propellant is divided into two partial flows, one of which reaches the collecting container and the other to the second pump. Liquid in the return line goes directly to the inlet of the first pump without having to pass through the collection container. This means that both pumps are connected in series with one another, the second pump does not draw any liquid from the collection container, and the total liquid requirement of the system is thus reduced.
  • the first pump can have a larger capacity than the second pump, so that the return flow from the second pump is not sufficient to feed the first pump, so that the latter is forced to additionally draw in, as a rule, additionally cooled liquid from the collecting container, which, however does not apply to the second pump.
  • Both pumps therefore do not receive a relatively cold liquid, which would increase the viscosity and make suction difficult.
  • both pumps operate at a relatively low operating temperature.
  • the hydraulic system is designed in such a way that, in use, the first branch is constantly carrying liquid, so that liquid is returned to the collecting container for cooling purposes.
  • the pump with the higher output is used to drive a plurality of spindle mowing units which form the first vehicle component.
  • This hydraulic system is particularly suitable for a vehicle which is designed as a lawn tractor with a front-side provided and heat-generating internal combustion engine, the collecting container being arranged in a rear vehicle area and thus not being affected by the heat development of the engine.
  • the first and second pumps and the first and second propellants can be arranged in the front area of the lawn tractor without fear of overheating of the liquid, since the remote collecting container provides sufficient cooling even without an additional cooler.
  • a relatively compact design is given.
  • the second pump can be designed as a charge pump and can be connected to a hydrostatic pump which serves to drive at least one vehicle wheel, the housing of the hydrostatic pump being a drainage line has, which is connected to the return line.
  • the circuit of the hydrostatic drive is closed and only connected to the charge pump, so that liquid can be sucked in to compensate for the leakage liquid that reaches the return line through the drainage line.
  • the two circuits are completely separate from each other, and other vehicle components such as lifting cylinders and auxiliary steering can be operated via the charge pump.
  • the invention provides that the return line opens into the suction line in the immediate vicinity of the first pump.
  • FIG. 1 of the drawing includes a circuit diagram of a hydraulic system 10 that can be used on a vehicle 12 shown in FIG. 2.
  • the spindle mower units 14, vehicle wheels 16, 26 and other vehicle components, such as a hydraulic steering aid 18 and a lifting device 20 for raising and lowering the spindle mower units 14, can be driven or operated via the hydraulic system 10.
  • the vehicle 12 itself is also provided with an internal combustion engine 22 in an engine compartment 24, which is located in the front area of the vehicle between the two front Vehicle wheels 16 is provided.
  • the rear vehicle wheel 26 is also steerable and has a vehicle seat 28 above it, while a hydraulic fluid reservoir 30 is provided at the rear end of the vehicle 12 between the vehicle seat 28 and the only rear vehicle wheel 26.
  • the collecting container 30 is shown schematically in FIG. 1, from which it can be seen that a suction line 32 leads from this to a hydraulic gear pump 34 which is mounted in a front area of the vehicle 12.
  • This gear pump 34 draws hydraulic fluid from the reservoir 30 for driving hydraulic motors 36 driving the spindle mowing units 14.
  • a mower unit 14 is provided in front of the two front vehicle wheels 16 and a single mower unit in front of the rear vehicle wheel 26. Each mower unit 14 is driven by a separate hydraulic motor 36.
  • Liquid emerging from the hydraulic motors 36 flows into a branch line 38 which has a first and a second branch 40 and 42.
  • the first branch 40 is designed as a return line, which extends backwards to the collecting container 30 and discharges part of the liquid into the collecting container 30 for cooling purposes.
  • the second branch 42 is connected to a charge pump 44 which supplies a hydrostatic pump 46 with liquid.
  • the hydrostatic pump 46 drives the drivable vehicle wheels.
  • Other vehicle components, such as the hydraulic steering aid 18 and the lifting mechanism 20, are charged with liquid from the charge pump 44.
  • the hydrostatic pump 46 and the hydraulic motors 48 driving the vehicle wheels 16 and 26 basically work as a system separate from the rest of the hydraulic system 10. Both However, systems are chained together via the drain line 47 of the pump housing, which opens into the second return line 50, and via the charge pump 44, which presses liquid into the hydraulic system of the hydrostatic pump 46 in order to add liquid that has escaped through the drain line 47 replace.
  • the second return line 50 returns liquid from the steering aid 18, the lifting mechanism 20 and from the drain line 47 to a location in the suction line 32 which is close to the gear pump 34, so that the return liquid from the return line 50 is fed directly to the gear pump 34, without first getting completely into the collecting container 30, which is far away from the gear pump. Since this return liquid is thus fed directly to the gear pump 34, the gear pump only sucks a relatively small amount of liquid through the suction line 32 from the remote collecting container 30. In addition, there is very little cavitation due to the pressure drop in the relatively long suction line 32.
  • the gear pump 34 has a higher flow rate or capacity than the charge pump 44.
  • the gear pump pumps a larger amount of liquid than the charge pump 44 is able to pump.
  • the charge pump 44 cannot take up the entire amount pumped by the gear pump 34 and only takes up a part of the liquid conveyed by the gear pump 34 via the second branch 42.
  • the liquid that is not required or sucked in by the charge pump gets into the first branch 40 and thus into the collecting container 30.
  • the difference in the pump performance also ensures that part of the liquid is returned to the collecting container 30 via the first branch 40 for cooling purposes reached.
  • the difference in the pump capacities ensures that part of the liquid which the gear pump 34 sucks comes out of the collecting container 30 via the suction line 32.
  • the charge pump 44 delivers a smaller amount of liquid than the gear pump 34, so that the gear pump 34 requires more liquid than the charge pump 44 can provide via the second return line 50. Since only a part of the liquid required by the gear pump 34 can be made available via the second return line, the remaining amount is sucked out of the collecting container 30 via the suction line 32.
  • the difference in pump capacities thus ensures that at least a small portion of the chilled liquid is drawn from the remote reservoir 30 and circulates in the system so that a relatively low liquid temperature can be maintained during operation.
  • the collection container is located approximately 1 m from the gear pump 34 so that the suction line has a length of approximately 1 m.
  • the gear pump has a capacity of 21.8 l per min (5.76 gal / min) or 6 cm3 per revolution (0.37 cu.in./rev) at 3600 rpm.
  • the charge pump has a work rate of 5.65 1 / min (1.5 gal / min) at 56 at (800 psi) and 15.12 1 / min (4 gal / min) at 3.5 at (50 psi) .
  • the hydrostatic pump 46 has a capacity of 45.4 to 68 l / min (12-18 gal / min).
  • the preferred exemplary embodiment of the present invention is based on a hydraulic system 10, the collecting container 30 of which is arranged at some distance from the hot or at least warm engine compartment, so that the liquid in the collecting container is not heated by the engine and is therefore easier to cool is.
  • the flow of the hydraulic fluid between the gear pump 34, which drives the motors 36 of the cylinder mower 14, and the charge pump 44, which drives the vehicle components 18 and 20, at least does so a reduction in the formation of cavitation, because the amount of liquid that is sucked in through the relatively long suction line 32 led to the collecting container 30 is reduced.
  • the system with a gear pump and with a charge pump of lower capacity ensures that part of the liquid required in the system is fed directly into the collection container and sucked out of the collection container, so that the operating temperature of the liquid remains correspondingly low.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Harvester Elements (AREA)

Abstract

In a hydraulic system for a vehicle, having a collecting tank (30), a first and second pump (34 and 44), a suction line (32) connecting the collecting tank (30) to the first pump (34), a first driving means (36) connected to the first pump (34) for driving a first vehicle component, a second driving means (46) connected to the second pump (44) for driving a second vehicle component, and a return line (50) for the second pump (44), a branch line (38) attached to the outlet of the first driving means (36) is provided with a first branch (40) connected to the collecting tank (30) and with a second branch (42) attached to the second pump (44), the return line (50) being connected to the suction line (32). <IMAGE>

Description

Die Erfindung bezieht sich auf ein hydraulisches System für ein Fahrzeug mit einem Sammelbehälter, einer ersten und einer zweiten Pumpe, einer den Sammelbehälter mit der ersten Pumpe verbindenden Saugleitung, einem ersten mit der ersten Pumpe verbundenen Treibmittel zum Antreiben einer ersten Fahrzeugkomponente, einem zweiten mit der zweiten Pumpe verbundenen Treibmittel zum Antreiben einer zweiten Fahrzeugkomponente und einer Rücklaufleitung für die zweite Pumpe.The invention relates to a hydraulic system for a vehicle with a collection container, a first and a second pump, a suction line connecting the collection container to the first pump, a first propellant connected to the first pump for driving a first vehicle component, a second with the second pump connected propellant for driving a second vehicle component and a return line for the second pump.

Dieses hydraulische System (US-A-5 069 037) ist für einen Rasentraktor konzipiert, der zwischen seinen vorderen und rückwärtigen Rädern mit einem Sichelmäher versehen ist. Die erste Pumpe gehört zu einem hydrostatischen Antrieb für die rückwärtigen Räder, während die zweite Pumpe Teil einer Hilfskraftlenkung ist und zum Druckbeaufschlagen von Hubzylindern dient. Beide Pumpen sind im Bereich eines rückwärtigen Fahrzeuggetriebes angeordnet, dessen Sumpf auch als Sammelbehälter für das hydraulische System dient, und haben einen eigenen hydraulischen Kreislauf mit einer gemeinsamen Saugleitung. Die Pumpen sind damit zueinander parallel geschaltet, so daß jede Pumpe den erforderlichen Flüssigkeitsbedarf gesondert ansaugt. Damit wird eine relativ große Flüssigkeitsmenge benötigt, auch wenn die Pumpen unterschiedliche Kapazitäten haben.This hydraulic system (US-A-5 069 037) is designed for a lawn tractor that is equipped with a sickle mower between its front and rear wheels. The first pump is part of a hydrostatic drive for the rear wheels, while the second pump is part of an auxiliary power steering system and is used to pressurize lifting cylinders. Both pumps are arranged in the area of a rear vehicle transmission, the sump of which also serves as a collecting tank for the hydraulic system, and have their own hydraulic circuit with a common suction line. The pumps are thus connected in parallel to each other so that each pump draws in the required liquid separately. This requires a relatively large amount of liquid, even if the pumps have different capacities.

Solche Systeme sind kavitationsanfällig, insbesondere bei langen Saugleitungen und Pumpen mit einem marginalen Einlaßvakuum. Es entstehen in der Flüssigkeit Hohlraumbildungen durch Gasauscheidungen im Unterdruckbereich. Es bilden sich Dampfbläschen und ein ansteigender Druck führt zur Kondensation dieser Dampfbläschen. Die dabei auftretende Volumensänderung ist mit sehr starken Druckstößen verbunden, die eine starke Schallabstrahlung verursachen und zu einer allmählichen Zerstörung benachbarter fester Teile führen.Such systems are prone to cavitation, especially with long suction lines and pumps with a marginal inlet vacuum. Cavities are formed in the liquid due to gas excretion in the negative pressure area. Steam bubbles form and an increasing pressure leads to the condensation of these steam bubbles. The resulting change in volume is associated with very strong pressure surges, which cause strong sound radiation and lead to a gradual destruction of adjacent solid parts.

Andererseits gibt es auch hydraulische Systeme, die zum Antrieb von mehreren an einem Rasentraktor aufgehängten Sichelmähern dienen und die weniger kavitationsanfällig sind, weil sie relativ kompakt mit kurzen Leitungen ausgebildet sind. Die Sichelmäher sind dabei in der Regel vor der Maschine aufgehängt und werden durch eine Zahnradpumpe angetrieben. Ebenfalls im vorderen Fahrzeugbereich befindet sich eine an eine hydrostatische Pumpe angeschlossene Ladepumpe für den Antrieb der Fahrzeugräder und zum Betätigen anderer Fahrzeugkomponenten. Während des Einsatzes erhitzt sich die Flüssigkeit stark. Hinzu kommt das Hydraulikleitungen und andere hydraulische Komponenten relativ nah an dem sich ebenfalls im Einsatz aufheizenden Motorraum angeordnet sind, was ebenfalls zu einer zusätzlichen Erwärmung führt. Solche Systeme besitzen eine einzige Rücklaufleitung, die zu einem Sammelbehälter führt, der wegen der kompakten Bauweise ebenfalls im Frontbereich des Fahrzeuges vorgesehen ist. Damit kann wegen der Nähe zum Motor die Flüssigkeit nicht ausreichend gekühlt werden, sofern kein gesonderter Kühler vorgesehen ist. Ein solcher erhöht aber wiederum die Herstellungskosten.On the other hand, there are also hydraulic systems that drive several sickle mowers suspended on a lawn tractor and that are less prone to cavitation because they are relative are compact with short lines. The rotary mowers are usually suspended in front of the machine and are driven by a gear pump. Also located in the front of the vehicle is a charging pump connected to a hydrostatic pump for driving the vehicle wheels and for actuating other vehicle components. The liquid heats up strongly during use. Added to this is the fact that hydraulic lines and other hydraulic components are arranged relatively close to the engine compartment, which is also heating up in use, which also leads to additional heating. Such systems have a single return line that leads to a collecting container, which is also provided in the front area of the vehicle because of the compact design. Because of the proximity to the engine, the liquid cannot be cooled sufficiently unless a separate cooler is provided. However, this in turn increases the manufacturing costs.

Die mit der Erfindung zu lösende Aufgabe wird dementsprechend in einem verbesserten hydraulischen System gesehen, das zumindest einige der vorstehend aufgeführten Nachteile vermeidet. Nach der Erfindung ist deshalb eine an den Ausgang des ersten Treibmittels angeschlossene Abzweigleitung mit einem ersten mit dem Sammelbehälter verbundenen Abzweig und einem zweiten an die zweite Pumpe angeschlossenen Abzweig vorgesehen, wobei die Rücklaufleitung mit der Saugleitung verbunden ist. Auf diese Weise ist die Abzweigleitung stromabwärts des ersten Treibmittels angeschlossen, und aus diesem ersten Treibmittel austretende Flüssigkeit wird aufgeteilt in zwei Teilströme, von denen einer in den Sammelbehälter und der andere zu der zweiten Pumpe gelangt. Flüssigkeit in der Rücklaufleitung gelangt unmittelbar zum Eingang der ersten Pumpe, ohne den Sammelbehälter durchlaufen zu müssen. Beide Pumpen sind damit zueinander in Reihe geschaltet, die zweite Pumpe saugt keine Flüssigkeit aus dem Sammelbehälter an, und der Gesamtflüssigkeitsbedarf des Systems ist damit reduziert.The object to be achieved with the invention is accordingly seen in an improved hydraulic system which avoids at least some of the disadvantages listed above. According to the invention, therefore, a branch line connected to the outlet of the first propellant is provided with a first branch connected to the collecting container and a second branch connected to the second pump, the return line being connected to the suction line. In this way, the branch line is connected downstream of the first propellant, and liquid emerging from this first propellant is divided into two partial flows, one of which reaches the collecting container and the other to the second pump. Liquid in the return line goes directly to the inlet of the first pump without having to pass through the collection container. This means that both pumps are connected in series with one another, the second pump does not draw any liquid from the collection container, and the total liquid requirement of the system is thus reduced.

Vorteilhaft kann die erste Pumpe eine größere Kapazität als die zweite Pumpe aufweisen, so daß die Rücklaufmenge von der zweiten Pumpe nicht ausreicht, die erste Pumpe zu speisen, so daß diese gezwungen ist, in der Regel gekühlte Flüssigkeit zusätzlich aus dem Sammelbehälter anzusaugen, was aber für die zweite Pumpe nicht zutrifft. Beide Pumpen erhalten damit keine relativ kalte Flüssigkeit, wodurch die Viskosität erhöht und ein Ansaugen erschwert würde. Dennoch arbeiten beide Pumpen bei einer relativ niedrigen Betriebstemperatur.Advantageously, the first pump can have a larger capacity than the second pump, so that the return flow from the second pump is not sufficient to feed the first pump, so that the latter is forced to additionally draw in, as a rule, additionally cooled liquid from the collecting container, which, however does not apply to the second pump. Both pumps therefore do not receive a relatively cold liquid, which would increase the viscosity and make suction difficult. However, both pumps operate at a relatively low operating temperature.

Das hydraulische System ist nach einem weiteren Vorschlag der Erfindung derart ausgelegt, daß im Einsatz der erste Abzweig ständig Flüssigkeit führend ist, damit Flüssigkeit zu Kühlzwecken in den Sammelbehälter zurückgeführt wird.According to a further proposal of the invention, the hydraulic system is designed in such a way that, in use, the first branch is constantly carrying liquid, so that liquid is returned to the collecting container for cooling purposes.

Nach einem weiteren erfindungsgemäßen Vorschlag dient die Pumpe mit der größeren Leistung zum Antrieb mehrerer Spindelmäheinheiten, die die erste Fahrzeugkomponente bilden.According to a further proposal according to the invention, the pump with the higher output is used to drive a plurality of spindle mowing units which form the first vehicle component.

Dieses hydraulische System ist besonders geeignet für ein Fahrzeug, das als Rasentraktor mit frontseitig vorgesehenem und Hitze entwickelndem Verbrennungsmotor ausgebildet ist, wobei der Sammelbehälter in einem rückwärtigen Fahrzeugbereich angeordnet ist und damit von der Hitzeentwicklung des Motors nicht beeinträchtigt wird. In einem solchen Fall können die erste und zweite Pumpe und die ersten und zweiten Treibmittel im frontseitigen Bereich des Rasentraktors angeordnet sein, ohne daß eine Überhitzung der Flüssigkeit zu befürchten ist, da der abgelegene Sammelbehälter auch ohne zusätzlichen Kühler für eine ausreichende Kühlung sorgt. Eine relativ kompakte Bauweise ist gegeben.This hydraulic system is particularly suitable for a vehicle which is designed as a lawn tractor with a front-side provided and heat-generating internal combustion engine, the collecting container being arranged in a rear vehicle area and thus not being affected by the heat development of the engine. In such a case, the first and second pumps and the first and second propellants can be arranged in the front area of the lawn tractor without fear of overheating of the liquid, since the remote collecting container provides sufficient cooling even without an additional cooler. A relatively compact design is given.

In weiterer Fortbildung der Erfindung kann die zweite Pumpe als Ladepumpe ausgebildet und mit einer hydrostatischen Pumpe, die zum Antrieb mindestens eines Fahrzeugrades dient, verbunden sein, wobei das Gehäuse der hydrostatischen Pumpe eine Drainageleitung aufweist, die an die Rücklaufleitung angeschlossen ist. Der Kreislauf des hydrostatischen Antriebes ist geschlossen und nur mit der Ladepumpe verbunden, so daß Flüssigkeit nachgesaugt werden kann, um die Leckflüssigkeit, die durch die Drainageleitung in die Rücklaufleitung gelangt, auszugleichen. Außer diesen beiden Verbindungen sind die beiden Kreisläufe voneinander vollständig getrennt, wobei über die Ladepumpe noch andere Fahrzeugkomponenten, wie Hubzylinder und eine Hilfslenkung betrieben werden können.In a further development of the invention, the second pump can be designed as a charge pump and can be connected to a hydrostatic pump which serves to drive at least one vehicle wheel, the housing of the hydrostatic pump being a drainage line has, which is connected to the return line. The circuit of the hydrostatic drive is closed and only connected to the charge pump, so that liquid can be sucked in to compensate for the leakage liquid that reaches the return line through the drainage line. In addition to these two connections, the two circuits are completely separate from each other, and other vehicle components such as lifting cylinders and auxiliary steering can be operated via the charge pump.

Um die Kavitationsgefahr noch weiter zu begrenzen, sieht die Erfindung schließlich vor, daß die Rücklaufleitung in unmittelbarer Nähe der ersten Pumpe in die Saugleitung mündet.Finally, in order to further limit the risk of cavitation, the invention provides that the return line opens into the suction line in the immediate vicinity of the first pump.

In der Zeichnung ist ein Ausführungsbeispiel der Erfindung dargestellt. Es zeigt:

Fig. 1
ein hydraulisches System in schematischer Darstellung und
Fig. 2
einen insbesondere auf Golfplätzen einsetzbaren Spindelrasenmäher, an dem das hydraulische System realisiert ist.
In the drawing, an embodiment of the invention is shown. It shows:
Fig. 1
a hydraulic system in a schematic representation and
Fig. 2
a spindle lawn mower that can be used in particular on golf courses and on which the hydraulic system is implemented.

Fig. 1 der Zeichnung beinhaltet ein Schaltdiagramm eines hydraulischen Systems 10, das an einem in Fig. 2 gezeigten Fahrzeug 12 Verwendung finden kann. An einem derartigen Fahrzeug können hydraulisch antreibbare Spindelmäheinheiten 14 angeschlossen werden, wie sie zur Pflege von Golfplätzen oder dergleichen eingesetzt werden. Über das hydraulische System 10 sind die Spindelmäheinheiten 14, Fahrzeugräder 16, 26 und weitere Fahrzeugkomponenten, wie eine hydraulische Lenkhilfe 18 und eine Hubeinrichtung 20 zum Anheben und Absenken der Spindelmäheinheiten 14 an- bzw. betreibbar. Das Fahrzeug 12 selbst ist noch mit einem Verbrennungsmotor 22 in einem Motorraum 24 versehen, der im vorderen Bereich des Fahrzeuges zwischen den beiden vorderen Fahrzeugrädern 16 vorgesehen ist. Das rückwärtige Fahrzeugrad 26 ist außerdem lenkbar und über ihm befindet sich ein Fahrzeugsitz 28, während ein Sammelbehälter 30 für hydraulische Flüssigkeit an dem rückwärtigen Ende des Fahrzeuges 12 zwischen dem Fahrzeugsitz 28 und dem einzigen rückwärtigen Fahrzeugrad 26 vorgesehen ist. Der Sammelbehälter 30 ist schematisch in Fig. 1 eingezeichnet, aus der zu erkennen ist, daß von diesem eine Saugleitung 32 zu einer hydraulischen Zahnradpumpe 34 führt, die in einem vorderen Bereich des Fahrzeuges 12 montiert ist. Diese Zahnradpumpe 34 saugt hydraulische Flüssigkeit aus dem Sammelbehälter 30 für den Antrieb von die Spindelmäheinheiten 14 antreibenden Hydromotoren 36 an. Beim Ausführungsbeispiel sind je eine Mäheinheit 14 vor den beiden vorderen Fahrzeugrädern 16 und eine einzige Mäheinheit vor dem rückwärtigen Fahrzeugrad 26 vorgesehen. Jede Mäheinheit 14 wird über einen gesonderten Hydromotor 36 angetrieben. Aus den Hydromotoren 36 austretende Flüssigkeit fließt in eine Abzweigleitung 38, die einen ersten und einen zweiten Abzweig 40 und 42 aufweist. Hierbei ist der erste Abzweig 40 als Rücklaufleitung ausgebildet, die sich nach rückwärts bis zu den Sammelbehälter 30 erstreckt und einen Teil der Flüssigkeit zu Kühlzwecken in den Sammelbehälter 30 abführt. Der zweite Abzweig 42 ist an eine Ladepumpe 44 angeschlossen, die eine hydrostatische Pumpe 46 mit Flüssigkeit beliefert. Die hydrostatische Pumpe 46 treibt die antreibbaren Fahrzeugräder an. Andere Fahrzeugkomponenten, wie die hydraulische Lenkhilfe 18 und der Hebemechanismus 20 werden von der Ladepumpe 44 aus mit Flüssigkeit beschickt. Aus der Lenkhilfe 18 und aus dem Hebemechanismus 20 austretende Flüssigkeit sowie aus dem Pumpengehäuse durch eine Drainageleitung 47 austretende Flüssigkeit gelangt in eine zweite Rücklaufleitung 50, die ihrerseits an die Saugleitung 32 angeschlossen ist und zwar an einer Stelle, die zwischen der Zahnradpumpe 34 und dem Sammelbehälter 30 liegt.FIG. 1 of the drawing includes a circuit diagram of a hydraulic system 10 that can be used on a vehicle 12 shown in FIG. 2. Hydraulically drivable spindle mowing units 14, such as those used for the maintenance of golf courses or the like, can be connected to such a vehicle. The spindle mower units 14, vehicle wheels 16, 26 and other vehicle components, such as a hydraulic steering aid 18 and a lifting device 20 for raising and lowering the spindle mower units 14, can be driven or operated via the hydraulic system 10. The vehicle 12 itself is also provided with an internal combustion engine 22 in an engine compartment 24, which is located in the front area of the vehicle between the two front Vehicle wheels 16 is provided. The rear vehicle wheel 26 is also steerable and has a vehicle seat 28 above it, while a hydraulic fluid reservoir 30 is provided at the rear end of the vehicle 12 between the vehicle seat 28 and the only rear vehicle wheel 26. The collecting container 30 is shown schematically in FIG. 1, from which it can be seen that a suction line 32 leads from this to a hydraulic gear pump 34 which is mounted in a front area of the vehicle 12. This gear pump 34 draws hydraulic fluid from the reservoir 30 for driving hydraulic motors 36 driving the spindle mowing units 14. In the exemplary embodiment, a mower unit 14 is provided in front of the two front vehicle wheels 16 and a single mower unit in front of the rear vehicle wheel 26. Each mower unit 14 is driven by a separate hydraulic motor 36. Liquid emerging from the hydraulic motors 36 flows into a branch line 38 which has a first and a second branch 40 and 42. Here, the first branch 40 is designed as a return line, which extends backwards to the collecting container 30 and discharges part of the liquid into the collecting container 30 for cooling purposes. The second branch 42 is connected to a charge pump 44 which supplies a hydrostatic pump 46 with liquid. The hydrostatic pump 46 drives the drivable vehicle wheels. Other vehicle components, such as the hydraulic steering aid 18 and the lifting mechanism 20, are charged with liquid from the charge pump 44. Liquid emerging from the steering aid 18 and from the lifting mechanism 20 and liquid emerging from the pump housing through a drain line 47 enters a second return line 50, which in turn is connected to the suction line 32 at a point between the gear pump 34 and the collecting container 30 lies.

Die hydrostatische Pumpe 46 und die Fahrzeugräder 16 und 26 antreibende Hydromotore 48 arbeiten grundsätzlich als ein von dem übrigen hydraulischen System 10 getrenntes System. Beide Systeme sind allerdings über die Drainageleitung 47 des Pumpengehäuses, die in die zweite Rücklaufleitung 50 mündet, und über die Ladepumpe 44 miteinander verkettet, die Flüssigkeit in das hydraulische System der hydrostatischen Pumpe 46 drückt, um Flüssigkeit, die durch die Drainageleitung 47 ausgetreten ist, zu ersetzen.The hydrostatic pump 46 and the hydraulic motors 48 driving the vehicle wheels 16 and 26 basically work as a system separate from the rest of the hydraulic system 10. Both However, systems are chained together via the drain line 47 of the pump housing, which opens into the second return line 50, and via the charge pump 44, which presses liquid into the hydraulic system of the hydrostatic pump 46 in order to add liquid that has escaped through the drain line 47 replace.

Die zweite Rücklaufleitung 50 führt Flüssigkeit aus der Lenkhilfe 18, dem Hebemechanismus 20 und aus der Drainageleitung 47 zu einer Stelle in der Saugleitung 32 zurück, die nahe der Zahnradpumpe 34 liegt, so daß die Rücklaufflüssigkeit aus der Rücklaufleitung 50 direkt der Zahnradpumpe 34 zugefördert wird, ohne zunächst vollständig in den von der Zahnradpumpe weit entfernt liegenden Sammelbehälter 30 zu gelangen. Da somit diese Rücklaufflüssigkeit direkt der Zahnradpumpe 34 zugeführt wird, saugt die Zahnradpumpe lediglich eine relativ kleine Menge Flüssigkeit durch die Saugleitung 32 aus dem abgelegenen Sammelbehälter 30 an. Außerdem tritt nur eine äußerst geringe Kavitation infolge des Druckabfalls in der relativ langen Saugleitung 32 auf.The second return line 50 returns liquid from the steering aid 18, the lifting mechanism 20 and from the drain line 47 to a location in the suction line 32 which is close to the gear pump 34, so that the return liquid from the return line 50 is fed directly to the gear pump 34, without first getting completely into the collecting container 30, which is far away from the gear pump. Since this return liquid is thus fed directly to the gear pump 34, the gear pump only sucks a relatively small amount of liquid through the suction line 32 from the remote collecting container 30. In addition, there is very little cavitation due to the pressure drop in the relatively long suction line 32.

Andererseits wird nicht die gesamte Flüssigkeitsmenge aus der Rücklaufleitung 50 der Zahnradpumpe 34 zugeführt, da das System so ausgebildet ist, daß ein Teil dieser Flüssigkeit zu Kühlzwecken in den Sammelbehälter 30 geleitet wird. Die Zahnradpumpe 34 hat im Einsatz eine höhere Durchflußrate oder Kapazität als die Ladepumpe 44. Die Zahnradpumpe pumpt nämlich eine größere Menge Flüssigkeit als die Ladepumpe 44 in der Lage ist zu pumpen. Die Ladepumpe 44 kann nicht die gesamte von der Zahnradpumpe 34 gepumpte Menge aufnehmen und nimmt nur einen Teil der von der Zahnradpumpe 34 geförderten Flüssigkeit über den zweiten Abzweig 42 auf. Die von der Ladepumpe nicht benötigte oder angesaugte Flüssigkeit gelangt in den ersten Abzweig 40 und damit in den Sammelbehälter 30. Der Unterschied in der Pumpenleistung stellt damit auch sicher, daß ein Teil der Flüssigkeit zu Kühlzwecken über den ersten Abzweig 40 wieder zurück in den Sammelbehälter 30 gelangt.On the other hand, the entire amount of liquid is not supplied from the return line 50 to the gear pump 34, since the system is designed such that a part of this liquid is passed into the collecting container 30 for cooling purposes. In use, the gear pump 34 has a higher flow rate or capacity than the charge pump 44. The gear pump pumps a larger amount of liquid than the charge pump 44 is able to pump. The charge pump 44 cannot take up the entire amount pumped by the gear pump 34 and only takes up a part of the liquid conveyed by the gear pump 34 via the second branch 42. The liquid that is not required or sucked in by the charge pump gets into the first branch 40 and thus into the collecting container 30. The difference in the pump performance also ensures that part of the liquid is returned to the collecting container 30 via the first branch 40 for cooling purposes reached.

In gleicher Weise stellt der Unterschied in den Pumpenkapazitäten sicher, daß ein Teil der Flüssigkeit, den die Zahnradpumpe 34 ansaugt, über die Saugleitung 32 aus dem Sammelbehälter 30 kommt. Die Ladepumpe 44 fördert eine kleinere Menge Flüssigkeit als die Zahnradpumpe 34 , so daß die Zahnradpumpe 34 mehr Flüssigkeit benötigt, als die Ladepumpe 44 über die zweite Rücklaufleitung 50 zur Verfügung stellen kann. Da nur ein Teil der von der Zahnradpumpe 34 benötigten Flüssigkeit über die zweite Rücklaufleitung zur Verfügung gestellt werden kann, wird die verbleibende Restmenge aus dem Sammelbehälter 30 über die Saugleitung 32 angesaugt. Der Unterschied in den Pumpenkapazitäten stellt damit sicher, daß zumindest ein kleiner Teil gekühlter Flüssigkeit aus dem entfernt liegenden Sammelbehälter 30 angesaugt wird und in dem System zirkuliert, damit während des Betriebes eine relativ niedrige Flüssigkeitstemperatur aufrechterhalten bleiben kann.In the same way, the difference in the pump capacities ensures that part of the liquid which the gear pump 34 sucks comes out of the collecting container 30 via the suction line 32. The charge pump 44 delivers a smaller amount of liquid than the gear pump 34, so that the gear pump 34 requires more liquid than the charge pump 44 can provide via the second return line 50. Since only a part of the liquid required by the gear pump 34 can be made available via the second return line, the remaining amount is sucked out of the collecting container 30 via the suction line 32. The difference in pump capacities thus ensures that at least a small portion of the chilled liquid is drawn from the remote reservoir 30 and circulates in the system so that a relatively low liquid temperature can be maintained during operation.

Bei dem bevorzugten Ausführungsbeispiel der vorliegenden Erfindung ist der Sammelbehälter etwa 1 m von der Zahnradpumpe 34 entfernt angeordnet, do daß die Saugleitung eine Länge von etwa 1 m hat. Die Zahnradpumpe hat eine Kapazität von 21,8 l pro min (5,76 gal/min) oder von 6 cm³ pro Umdrehung (0,37 cu.in./rev) bei 3600 U/min. Die Ladepumpe hat eine Arbeitsleistung von 5,65 1/min (1,5 gal/min) bei 56 at (800 psi) und von 15,12 1/min (4 gal/min) bei 3,5 at (50 psi). Die hydrostatische Pumpe 46 hat eine Kapazität von 45,4 bis 68 l/min (12-18 gal/min).In the preferred embodiment of the present invention, the collection container is located approximately 1 m from the gear pump 34 so that the suction line has a length of approximately 1 m. The gear pump has a capacity of 21.8 l per min (5.76 gal / min) or 6 cm³ per revolution (0.37 cu.in./rev) at 3600 rpm. The charge pump has a work rate of 5.65 1 / min (1.5 gal / min) at 56 at (800 psi) and 15.12 1 / min (4 gal / min) at 3.5 at (50 psi) . The hydrostatic pump 46 has a capacity of 45.4 to 68 l / min (12-18 gal / min).

Dem bevorzugten Ausführungsbeispiel der vorliegenden Erfindung liegt damit ein hydraulisches System 10 zugrunde, dessen Sammelbehälter 30 mit einigem Abstand zu dem im Einsatz heißen oder zumindest warmen Motorraum angeordnet ist, so daß die sich im Sammelbehälter befindliche Flüssigkeit durch den Motor nicht aufgeheizt wird und deshalb besser kühlbar ist. Das Leiten der hydraulischen Flüssigkeit zwischen der Zahnradpumpe 34, die die Motoren 36 der Spindelmäher 14 antreibt, und der Ladepumpe 44, die die Fahrzeugkomponenten 18 und 20 antreibt, bewirkt zumindest eine Minderung der Kavitationsbildung, weil die Flüssigkeitsmenge, die durch die relativ lange zum Sammelbehälter 30 geführte Saugleitung 32 angesaugt wird, reduziert ist. Das System mit einer Zahnradpumpe und mit einer Ladepumpe von geringerer Kapazität stellt sicher, daß ein Teil der im System benötigten Flüssigkeit direkt in den Sammelbehälter geleitet und aus dem Sammelbehälter gesaugt wird, so daß die Betriebstemperatur der Flüssigkeit entsprechend niedrig bleibt.The preferred exemplary embodiment of the present invention is based on a hydraulic system 10, the collecting container 30 of which is arranged at some distance from the hot or at least warm engine compartment, so that the liquid in the collecting container is not heated by the engine and is therefore easier to cool is. The flow of the hydraulic fluid between the gear pump 34, which drives the motors 36 of the cylinder mower 14, and the charge pump 44, which drives the vehicle components 18 and 20, at least does so a reduction in the formation of cavitation, because the amount of liquid that is sucked in through the relatively long suction line 32 led to the collecting container 30 is reduced. The system with a gear pump and with a charge pump of lower capacity ensures that part of the liquid required in the system is fed directly into the collection container and sucked out of the collection container, so that the operating temperature of the liquid remains correspondingly low.

Claims (7)

Hydraulisches System für ein Fahrzeug (12) mit einem Sammelbehälter (30), einer ersten und einer zweiten Pumpe (34 und 44), einer den Sammelbehälter (30) mit der ersten Pumpe (34) verbindenden Saugleitung (32), einem ersten mit der ersten Pumpe (34) verbundenen Treibmittel (36) zum Antreiben einer ersten Fahrzeugkomponente, einem zweiten mit der zweiten Pumpe (44) verbundenen Treibmittel (46) zum Antreiben einer zweiten Fahrzeugkomponente und einer Rücklaufleitung (50) für die zweite Pumpe (44), gekennzeichnet durch eine an den Ausgang des ersten Treibmittels (34) angeschlossene Abzweigleitung (38) mit einem ersten mit dem Sammelbehälter (30) verbundenen Abzweig (40) und einem zweiten an die zweite Pumpe (44) angeschlossenen Abzweig (42), wobei die Rücklaufleitung (50) mit der Saugleitung (32) verbunden ist.Hydraulic system for a vehicle (12) with a collecting tank (30), a first and a second pump (34 and 44), a suction line (32) connecting the collecting tank (30) with the first pump (34), a first with the First pump (34) connected propellant (36) for driving a first vehicle component, a second propellant (46) connected to the second pump (44) for driving a second vehicle component and a return line (50) for the second pump (44) by means of a branch line (38) connected to the outlet of the first propellant (34) with a first branch (40) connected to the collecting container (30) and a second branch (42) connected to the second pump (44), the return line ( 50) is connected to the suction line (32). Hydraulisches System nach Anspruch 1, dadurch gekennzeichnet, daß die erste Pumpe (34) eine größere Kapazität als die zweite Pumpe (44) hat.Hydraulic system according to claim 1, characterized in that the first pump (34) has a larger capacity than the second pump (44). Hydraulisches System nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß im Einsatz der erste Abzweig (40) ständig Flüssigkeit führend ist.Hydraulic system according to Claim 1 or 2, characterized in that the first branch (40) is always liquid-carrying in use. Hydraulisches System nach einem oder mehreren der vorherigen Ansprüche, dadurch gekennzeichnet, daß die erste Fahrzeugkomponente aus mehreren Spindelmäheinheiten (14) besteht.Hydraulic system according to one or more of the preceding claims, characterized in that the first vehicle component consists of several spindle mowing units (14). Hydraulisches System nach einem oder mehreren der vorherigen Ansprüche, wobei das Fahrzeug (12) als Rasentraktor mit frontseitig vorgesehenem Verbrennungsmotor (20) ausgebildet und der Sammelbehälter (30) in einem rückwärtigen Fahrzeugbereich angeordnet ist, dadurch gekennzeichnet, daß die erste und zweite Pumpe (34 und 44) und die ersten und zweiten Treibmittel (36, 46) im frontseitigen Bereich des Rasentraktors angeordnet sind.Hydraulic system according to one or more of the preceding claims, wherein the vehicle (12) is designed as a lawn tractor with an internal combustion engine (20) provided on the front and the collecting container (30) in a rear vehicle area is arranged, characterized in that the first and second pumps (34 and 44) and the first and second propellants (36, 46) are arranged in the front area of the lawn tractor. Hydraulisches System nach einem oder mehreren der vorherigen Ansprüche, dadurch gekennzeichnet, daß die zweite Pumpe als Ladepumpe (44) ausgebildet ist und mit einer hydrostatischen Pumpe (46), die zum Antrieb mindestens eines Fahrzeugrades (16, 26) dient, verbunden ist, wobei das Gehäuse der hydrostatischen Pumpe (46) eine Drainageleitung (47) aufweist, die an die Rücklaufleitung (50) angeschlossen ist.Hydraulic system according to one or more of the preceding claims, characterized in that the second pump is designed as a charging pump (44) and is connected to a hydrostatic pump (46) which serves to drive at least one vehicle wheel (16, 26), wherein the housing of the hydrostatic pump (46) has a drainage line (47) which is connected to the return line (50). Hydraulisches System nach einem oder mehreren der vorherigen Ansprüche, dadurch gekennzeichnet, daß die Rücklaufleitung (50) in unmittelbarer Nähe der ersten Pumpe (34) in die Saugleitung (32) mündet.Hydraulic system according to one or more of the preceding claims, characterized in that the return line (50) opens into the suction line (32) in the immediate vicinity of the first pump (34).
EP93120792A 1993-01-21 1993-12-23 Hydraulic system for a vehicle Expired - Lifetime EP0607604B1 (en)

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US08/006,897 US5335494A (en) 1993-01-21 1993-01-21 Hydraulic system for reel mower vehicles
US6897 1993-01-21

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EP0607604B1 EP0607604B1 (en) 1997-03-12

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EP93120792A Expired - Lifetime EP0607604B1 (en) 1993-01-21 1993-12-23 Hydraulic system for a vehicle

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US (1) US5335494A (en)
EP (1) EP0607604B1 (en)
CA (1) CA2109291C (en)
DE (1) DE59305767D1 (en)

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US5533325A (en) * 1994-02-03 1996-07-09 The Toro Company All wheel hydraulic drive system
JP3430662B2 (en) * 1994-09-21 2003-07-28 日産自動車株式会社 Vehicle driving force transmission device
JP3013225B2 (en) * 1995-01-11 2000-02-28 新キャタピラー三菱株式会社 Hanging work control device
US6018895A (en) * 1996-03-28 2000-02-01 Clark Equipment Company Valve stack in a mini-excavator directing fluid under pressure from multiple pumps to actuable elements
AU720849B2 (en) * 1996-03-28 2000-06-15 Clark Equipment Company Multifunction valve stack
US5810110A (en) * 1996-11-08 1998-09-22 R. H. Sheppard Co., Inc. Tandem power steering system with heat sink
US6182588B1 (en) * 1998-05-01 2001-02-06 Flexi-Coil Ltd. Hydraulic system having boost pump in series with a primary pump and a boost pump drive therefor
US7401465B2 (en) * 2005-11-16 2008-07-22 Deere & Company Dual pump dual pressure hydraulic circuit
US7568331B2 (en) * 2005-12-21 2009-08-04 Deere & Company Extendable lift arms for trim mower

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DE3406228A1 (en) * 1984-02-21 1985-08-29 Mannesmann Rexroth GmbH, 8770 Lohr Hydraulic system for an agricultural tractor
US5069037A (en) * 1989-12-05 1991-12-03 Kanzaki Kokyukoki Mfg. Co., Ltd. Fluid supply system for vehicles

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US3915068A (en) * 1974-08-30 1975-10-28 Deere & Co Hydrostatic transmission
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JPH07116721B2 (en) * 1989-01-31 1995-12-13 油谷重工株式会社 Hydraulic circuit of hydraulic excavator
JPH02236002A (en) * 1989-03-08 1990-09-18 Kubota Ltd Hydraulic circuit for working vehicle elevator

Patent Citations (4)

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Publication number Priority date Publication date Assignee Title
US3962870A (en) * 1975-04-23 1976-06-15 International Harvester Company Variable volume dual pump circuit
DE3222106A1 (en) * 1982-06-11 1983-12-15 Robert Bosch Gmbh, 7000 Stuttgart Hydraulic control arrangement
DE3406228A1 (en) * 1984-02-21 1985-08-29 Mannesmann Rexroth GmbH, 8770 Lohr Hydraulic system for an agricultural tractor
US5069037A (en) * 1989-12-05 1991-12-03 Kanzaki Kokyukoki Mfg. Co., Ltd. Fluid supply system for vehicles

Also Published As

Publication number Publication date
CA2109291C (en) 1996-09-10
US5335494A (en) 1994-08-09
EP0607604B1 (en) 1997-03-12
DE59305767D1 (en) 1997-04-17
CA2109291A1 (en) 1994-07-22

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