EP0446757B1 - Hydraulic system to supply a variable displacement pump - Google Patents

Hydraulic system to supply a variable displacement pump Download PDF

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Publication number
EP0446757B1
EP0446757B1 EP91103253A EP91103253A EP0446757B1 EP 0446757 B1 EP0446757 B1 EP 0446757B1 EP 91103253 A EP91103253 A EP 91103253A EP 91103253 A EP91103253 A EP 91103253A EP 0446757 B1 EP0446757 B1 EP 0446757B1
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EP
European Patent Office
Prior art keywords
input
output
valve
pump
hydraulic
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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EP91103253A
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German (de)
French (fr)
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EP0446757A1 (en
Inventor
Donald James Macdonald
James Anton Miller
Derek Malcolm Eagles
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Deere and Co
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Deere and Co
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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
    • F15B11/161—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors with sensing of servomotor demand or load
    • F15B11/162—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors with sensing of servomotor demand or load for giving priority to particular servomotors or users
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
    • F04B49/007—Installations or systems with two or more pumps or pump cylinders, wherein the flow-path through the stages can be changed, e.g. from series to parallel
    • 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
    • F15B2211/40—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
    • F15B2211/45—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
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/61—Secondary circuits
    • F15B2211/611—Diverting circuits, e.g. for cooling or filtering
    • 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
    • F15B2211/613—Feeding 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

Definitions

  • the invention relates to a hydraulic system for supplying at least one first hydraulic function by means of a main pump which is charged by a charge pump, an excess partial liquid flow of the charge pump supplying at least one second hydraulic function.
  • the main pump is preferably a high-pressure pump with an adjustable delivery rate (variable pump), for example an axial piston pump, for supplying a closed hydraulic circuit.
  • variable pump for example an axial piston pump
  • the charge pump it is necessary that the charge pump have a flow rate that is sufficient to satisfy the liquid demand of the variable displacement pump even at a low engine speed.
  • the charge pump's liquid output increases, so that precautions must be taken to discharge excess amounts of liquid that are not absorbed by the main pump.
  • variable displacement pump mainly only pumps a minimal flow of liquid over time, a large part of the liquid is unnecessarily directed back through the circuit to the reservoir. This leads to increased ventilation of the hydraulic fluid and to Loss of performance. In addition, large line cross sections are required to keep the pressure drop low.
  • DE-OS 35 00 310 describes a hydraulic system which has a control pump for supplying load circuits and a feed pump for supplying a supply circuit.
  • the pressure side of the feed pump is also connected to the suction side of the control pump. If the control pump for supplying the load circuit works at full capacity, it requires more pressure fluid than can be provided by the Seise Vietnamese. In this case, a liquid jet pump is activated to ensure that the control pump is supplied.
  • US Pat. No. 4,173,867 shows a hydraulic circuit in which a first pump supplies both a lubricating oil circuit and the charge pump for a variable displacement pump with liquid. If the pressure in the lubricating oil circuit drops, liquid is fed from the outlet of the charge pump to the lubricating oil circuit via a lubricating oil priority valve. This means that the supply of the lubricating oil circuit is given priority over the supply of the variable pump.
  • the object to be achieved with the invention is seen in specifying a hydraulic system of the type mentioned at the outset, in which the supply of a first hydraulic function fed by the main pump is given priority over a second hydraulic function and through which the delivery of excess amounts of liquid can be reduced and Power losses are minimized.
  • a liquid jet pump should be unnecessary.
  • a priority valve is connected to the charge pump, the main pump inlet and the second hydraulic function and optionally excess fluid not used by the main pump directs it from the charge pump to the second hydraulic function and an input of the charge pump.
  • a liquid jet pump for supplying the main pump is unnecessary.
  • the amount of liquid conveyed by the charge pump does not flow back to the reservoir unused, but serves to supply other circuits. This can reduce power losses and aeration of the liquid.
  • the priority valve is usually closed and prefers a liquid supply to the main pump. Depending on an increase in the inlet pressure of the main pump, excess charging fluid is delivered to the lubricating oil circuits through the priority valve from a predeterminable first pressure level. Depending on a further increase in the inlet pressure of the main pump, excess charging liquid is directed both to the lubricating oil circuits and to the inlet of the charging pump from a second pressure level.
  • variable displacement pump 14 which can be driven by a motor, a lubricating oil circuit, such as right and left driveline lubricating oil circuits 16, 18, a lubricating oil circuit 20 for a PTO and a lubricating oil circuit 22 for a pump drive.
  • the variable displacement pump 14 is, for example, an axial piston pump that serves to supply various hydraulic functions 15, such as steering, brakes and control valves, with liquid under pressure.
  • a hydraulic control circuit 28 receives hydraulic fluid from the charge pump 12 and a downstream filter circuit 30 and distributes this to the main pump 14 and the lubricating oil circuit 16-22.
  • the filter circuit 30 contains a filter 32, a check valve 34, (optionally) a strainer 36 and a filter bypass valve 38. Hydraulic fluid is passed through line 44 from the charge pump 12 to the inlet of the valve 38 and to the inlet side of the filter 32.
  • the output side of the filter 32 is connected via a check valve 34 and the lines 46 and 48 to the input of the main pump 14 and via the scanning line 49 to a control chamber which is located on the side of the valve 38 which is also attacked by a return spring.
  • a first outlet of the valve 38 is connected to the line 46 via the (optional) sieve 36.
  • a second outlet of the valve 38 is connected to the collecting container 10 via the line 50.
  • the scan line 54 connects line 44 to the pressure sensitive control port of valve 38.
  • Line 56 connects a third outlet of valve 38 to a pressure sensitive switch 58 which preferably triggers an indicator, such as a light bulb, on the dashboard when line 56 is pressurized.
  • Line 60 connects line 46 to the inlet of valve 40.
  • a first outlet 53 of valve 40 is connected via line 68 to lubricating oil circuits 20 and 22.
  • a second outlet 55 is connected to the lubricating oil circuits 16 and 18 via the orifice 78 and the line 70.
  • Channel 52 connects a third outlet 57 of valve 40 to the inlet of charge pump 12.
  • the inlet pressure of main pump 14 is applied to one end of spool or valve member 41 of valve 40 while the other end of spool or valve member 41 biased by a spring 43 and connected to the line 70 via the diaphragm 76 and the line 74.
  • the oil is drawn through the pre-filter 11 by the charge pump 12. From there it is pumped to the filter circuit 30.
  • the liquid is either passed through the oil filter 32 and the check valve 34, which prevents the connecting lines from leaking when changing the filter, or through the filter bypass valve 38.
  • the switch 58 outputs a display signal at 3.0 bar, which signals that the bypass condition has almost been reached, according to which bypass oil is only permitted when the pressure difference across the filter 32 reaches a value of 5 bar.
  • the bypass oil is passed through a 100 micron sieve 36 and then follows the same path that it would have taken under normal conditions as it passed through the filter 32.
  • the oil then flows to a point from where it flows to the input of the main pump 14 if necessary or, if there is no oil request from the main pump 14, to the boost pressure priority branch valve 40. No oil flows through the valve 40 if the pressure at the inlet of the main pump 14 does not exceed 0.5 bar. From 0.5 bar, the valve 40 adjusts itself so that it directs oil to the lubricating oil circuits 20 and 22. When these lubricating oil circuits reach a pressure of 1.0 bar, the valve 40 opens further and a cooling oil flow is directed to the lubricating oil circuits 16 and 18.
  • the pressure at the valve 40 reaches a value of 1.5 bar, this directs a part of the oil quantity coming from the charge pump 12 and the filter circuit 30 and entering the valve 40 to the channel 52, via which the oil returns to the suction side the charge pump 12 is guided.
  • the spring-loaded side of the slide 41 is connected to the line 70 via a line 74 and an orifice 76. To improve filter usage and cooling, a high proportion of the charging oil should flow through the lubricating oil circuit at maximum engine speed.
  • the charge pump 12 Since the charge pump 12 is oversized with regard to the maximum demand of the main pump 14, a flow rate for the lubricating oil circuit is available at all times. It is also believed that the main pump 14 rarely operates at full capacity, so the amount of oil available to the lubricating oil circuits should be more than sufficient.
  • the bypass function of the boost priority branch valve 40 through which excess oil is returned to the charge pump inlet, is intended to keep the flow rate of unfiltered oil through the oil filter 11 as low as possible. This is desirable in order for the system to operate with a charge pump 12 which is designed for 2.3 l / s at high idling speed and yet only absorbs 1.0 l / s of the unfiltered oil under most operating conditions.
  • the flow rate generated by the charge pump 12 must be sufficient to supply the main pump 14 at full delivery rate.
  • FIG. 2 shows an alternative embodiment of the invention, in which, however, the hydraulic circuit line 64 connects the outlet 59 of the valve 40 ′ via the line 80 and the orifice 81 to the inlet of the charge pump 12. Furthermore, line 62 connects a second inlet 61 of valve 40 'to the outlet of charge pump 12. Valve 40' has a first position in which all connections are blocked, a second position in which inlet 51 is connected to outlet 53 and a third position in which the input 51 is connected to the output 53 and the input 61 is connected to the output 59. Finally, in the embodiment according to FIG. 2, the output 53 is connected to the lines 68 and 70 via the line 66. A check valve 42 is disposed in line 68 to allow one-way fluid flow to functions 20 and 22 and to give priority to flow to functions 16 and 18.
  • charge pump 12 supplies oil to the main pump inlet either through filter 32 or, more likely, through filter bypass valve 38.
  • the boost pressure is likely to exceed 1.5 bar required to transfer excess boost flow through the bypass formed by valve 40 'to the inlet to direct the charge pump 12.
  • the circuit 28 is preferably located approximately equidistant from the main pump inlet and the charge pump inlet, and the bypass line 80 contains a restriction 81 so that the main pump 14 still enjoys priority. If no oil is requested by the main pump 14, the charge flow rate is passed on to the charge pump 12, which contributes to warming up the hydraulic circuit, and to the lubricating oil circuits 16-20.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Fluid-Pressure Circuits (AREA)
  • Control Of Fluid Gearings (AREA)
  • Control Of Positive-Displacement Pumps (AREA)
  • Rotary Pumps (AREA)

Abstract

A charge flow distribution valve routes all charge pump flow into a main pump until the main pump has sufficient inlet pressure. The valve opens to a first stage which routes excess charge flow to lubrication circuits. At a slightly higher main pump inlet pressure, it also routes oil to an inlet of the charge pump.

Description

Die Erfindung betrifft ein Hydrauliksystem zur Versorgung wenigstens einer ersten Hydraulikfunktion durch eine Hauptpumpe, die durch eine Ladepumpe geladen wird, wobei ein überschüssiger Flüssigkeitsteilstrom der Ladepumpe wenigstens eine zweite Hydraulikfunktion versorgt.The invention relates to a hydraulic system for supplying at least one first hydraulic function by means of a main pump which is charged by a charge pump, an excess partial liquid flow of the charge pump supplying at least one second hydraulic function.

Bei der Hauptpumpe handelt es sich vorzugsweise um eine Hochdruckpumpe mit verstellbarer Fördermenge (Verstellpumpe), beispielsweise eine Axialkolbenpumpe, zur Versorgung eines geschlossenen Hydraulikkreises. Wird eine durch einen Motor angetriebene Ladepumpe mit unveränderlicher Fördermenge verwendet, um Flüssigkeit an die Verstellpumpe zu liefern, so ist es erforderlich, daß die Ladepumpe eine Fördermenge aufweist, die ausreicht, um auch bei geringer Motordrehzahl die Flüssigkeitsanforderung der Verstellpumpe zu befriedigen. Bei hohen Motordrehzahlen steigt der Flüssigkeitsausstoß der Ladepumpe jedoch an, so daß Vorkehrungen getroffen werden müssen, um überschüssige Flüssigkeitsmengen, die nicht von der Hauptpumpe aufgenommen werden, abzuleiten.The main pump is preferably a high-pressure pump with an adjustable delivery rate (variable pump), for example an axial piston pump, for supplying a closed hydraulic circuit. If a motor-driven charge pump with a constant flow rate is used to deliver liquid to the variable displacement pump, it is necessary that the charge pump have a flow rate that is sufficient to satisfy the liquid demand of the variable displacement pump even at a low engine speed. At high engine speeds, however, the charge pump's liquid output increases, so that precautions must be taken to discharge excess amounts of liquid that are not absorbed by the main pump.

Üblicherweise wird eine überschüssige Flüssigkeitsmenge über ein Überdruckventil zurück zum Vorratsbehälter geleitet. Fördert die Verstellpumpe zeitlich überwiegend lediglich einen minimalen Flüssigkeitsstrom, so wird unnötigerweise ein Großteil der Flüssigkeit durch den Kreis zurück zum Vorratsbehälter geleitet. Dies führt zu einer verstärkten Belüftung der Hydraulikflüssigkeit und zu Leistungsverlusten. Ferner sind große Leitungsquerschnitte erforderlich, um den Druckabfall gering zu halten.An excess amount of liquid is usually directed back to the reservoir via a pressure relief valve. If the variable displacement pump mainly only pumps a minimal flow of liquid over time, a large part of the liquid is unnecessarily directed back through the circuit to the reservoir. This leads to increased ventilation of the hydraulic fluid and to Loss of performance. In addition, large line cross sections are required to keep the pressure drop low.

Durch die DE-OS 35 00 310 wird ein Hydrauliksystem beschrieben, das zur Versorgung von Lastkreisen eine Regelpumpe und zur Versorgung eines Speisekreises eine Speisepumpe aufweist. Die Druckseite der Speisepumpe ist auch mit der Ansaugseite der Regelpumpe verbunden. Arbeitet die Regelpumpe zur Versorgung des Lastkreises mit voller Leistung, so fordert sie mehr Druckflüssigkeit ab, als von dem Seisekreis zur Verfügung gestellt werden kann. In diesem Fall tritt eine Flüssigkeitsstrahlpumpe in Aktion, die die Versorgung der Regelpumpe sicherstellen soll.DE-OS 35 00 310 describes a hydraulic system which has a control pump for supplying load circuits and a feed pump for supplying a supply circuit. The pressure side of the feed pump is also connected to the suction side of the control pump. If the control pump for supplying the load circuit works at full capacity, it requires more pressure fluid than can be provided by the Seisekreis. In this case, a liquid jet pump is activated to ensure that the control pump is supplied.

Aus der US-PS 4,173,867 geht ein Hydraulikkreis hervor, bei dem eine erste Pumpe sowohl einen Schmierölkreis als auch die Ladepumpe für eine Verstellpumpe mit Flüssigkeit versorgt. Sinkt der Druck in dem Schmierölkreis ab, so wird über ein Schmierölprioritätsventil Flüssigkeit vom Ausgang der Ladepumpe dem Schmierölkreis zugeführt. Damit wird der Versorgung des Schmierölkreises die Priorität vor der Versorgung der Verstellpumpe gegeben.US Pat. No. 4,173,867 shows a hydraulic circuit in which a first pump supplies both a lubricating oil circuit and the charge pump for a variable displacement pump with liquid. If the pressure in the lubricating oil circuit drops, liquid is fed from the outlet of the charge pump to the lubricating oil circuit via a lubricating oil priority valve. This means that the supply of the lubricating oil circuit is given priority over the supply of the variable pump.

Durch die DE-B-27 05 721 ist ein Hydraulikkreis mit einer Haupt- und einer Ladepumpe der eingangs genannten Art bekannt geworden. Ein Teil der von der Ladepumpe geförderten Flüssigkeitsmenge wird für die Getriebeölung und die Kupplung verwendet, während der verbleibende Teil über ein Druckbegrenzungsventil eine Hauptpumpe läd, die ihrerseits Flüssigkeitsmotoren mit unter hohem Druck stehender Hydraulikflüssigkeit versorgt. Um die Flüssigkeitsmenge in der Druckleitung vor dem Druckbegrenzungsventil vergrößern zu können, steht diese Druckleitung über eine Venturi-Düsenpumpe mit dem Ausgang der Hauptpumpe derart in Verbindung, daß die Venturi-Düsenpumpe im Bedarfsfall Flüssigkeit aus einem Vorratsbehälter in die Druckleitung pumpt. Ein solcher Bedarfsfall ist gegeben, wenn bei geringen Geschwindigkeiten oder hohen Temperaturen die Ladepumpe keine ausreichende Kapazität aufweist, um die Hauptpumpe zu beaufschlagen.From DE-B-27 05 721 a hydraulic circuit with a main and a charge pump of the type mentioned has become known. Part of the amount of fluid delivered by the charge pump is used for the transmission oil and clutch, while the remaining part loads a main pump via a pressure relief valve, which in turn supplies hydraulic motors with high-pressure hydraulic fluid. In order to be able to increase the amount of liquid in the pressure line upstream of the pressure relief valve, this pressure line is connected to the outlet of the main pump via a Venturi nozzle pump in such a way that the Venturi nozzle pump pumps liquid from a reservoir into the pressure line if necessary. Such a need arises if the charge pump does not have sufficient capacity to act on the main pump at low speeds or high temperatures.

Die mit der Erfindung zu lösende Aufgabe wird darin gesehen, ein Hydrauliksystem der eingangs genannten Art anzugeben, bei dem der Versorgung einer ersten, durch die Hauptpumpe gespeisten Hydraulikfunktion die Priorität vor einer zweiten Hydraulikfunktion eingeräumt wird und durch das sich die Förderung überschüssiger Flüssigkeitsmengen vermindern läßt sowie Leistungsverluste minimiert werden. Eine Flüssigkeitsstrahlpumpe soll entbehrlich sein.The object to be achieved with the invention is seen in specifying a hydraulic system of the type mentioned at the outset, in which the supply of a first hydraulic function fed by the main pump is given priority over a second hydraulic function and through which the delivery of excess amounts of liquid can be reduced and Power losses are minimized. A liquid jet pump should be unnecessary.

Die Aufgabe wird erfindungsgemäß dadurch gelöst, daß ein Prioritätsventil mit der Ladepumpe, der Hauptpumpeneingang und der zweiten Hydraulikfunktion in Verbindung steht und wahlweise überschüssige, nicht von der Hauptpumpe beanspruchte Flüssigkeit von der Ladepumpe zu der zweiten Hydraulikfunktion und einem Eingang der Ladepumpe leitet.The object is achieved in that a priority valve is connected to the charge pump, the main pump inlet and the second hydraulic function and optionally excess fluid not used by the main pump directs it from the charge pump to the second hydraulic function and an input of the charge pump.

Bei dem erfindungsgemäßen Hydrauliksystem ist eine Flüssigkeitsstrahlpumpe zur Versorgung der Hauptpumpe entbehrlich. Die durch die Ladepumpe geförderte Flüssigkeitsmenge fließt nicht ungenutzt zum Vorratsbehälter zurück, sondern dient der Versorgung weiterer Kreise. Hierdurch lassen sich Leistungsverluste und eine Belüftung der Flüssigkeit verringern.In the hydraulic system according to the invention, a liquid jet pump for supplying the main pump is unnecessary. The amount of liquid conveyed by the charge pump does not flow back to the reservoir unused, but serves to supply other circuits. This can reduce power losses and aeration of the liquid.

Das Prioritätsventil ist gewöhnlich geschlossen und bevorzugt eine Flüssigkeitsversorgung der Hauptpumpe. In Abhängigkeit eines Ansteigens des Eingangsdruckes der Hauptpumpe wird überschüssige Ladeflüssigkeit durch das Prioritätsventil ab einem vorgebbaren ersten Druckniveau an Schmierölkreise abgegeben. Abhängig von einem weiteren Ansteigen des Eingangsdruckes der Hauptpumpe wird ab einem zweiten Druckniveau überschüssige Ladeflüssigkeit sowohl zu den Schmierölkreisen als auch an den Eingang der Ladepumpe geleitet.The priority valve is usually closed and prefers a liquid supply to the main pump. Depending on an increase in the inlet pressure of the main pump, excess charging fluid is delivered to the lubricating oil circuits through the priority valve from a predeterminable first pressure level. Depending on a further increase in the inlet pressure of the main pump, excess charging liquid is directed both to the lubricating oil circuits and to the inlet of the charging pump from a second pressure level.

Weitere vorteilhafte Ausgestaltungen und Weiterbildungen der Erfindung gehen aus den Unteransprüchen hervor.Further advantageous refinements and developments of the invention emerge from the subclaims.

Anhand der Zeichnung, die zwei Ausführungsbeispiele der Erfindung zeigt, sollen die Erfindung sowie weitere Vorteile und vorteilhafte Weiterbildungen und Ausgestaltungen der Erfindung näher beschrieben und erläutert werden.On the basis of the drawing, which shows two exemplary embodiments of the invention, the invention and further advantages and advantageous developments and refinements of the invention are to be described and explained in more detail.

Es zeigt:

Fig. 1
das vereinfachte Diagramm eines erfindungsgemäßen Hydraulikkreises zur Ladung einer Hauptverstellpumpe und
Fig. 2
das vereinfachte Diagramm einer alternativen Ausgestaltung der Erfindung.
It shows:
Fig. 1
the simplified diagram of a hydraulic circuit according to the invention for charging a main variable pump and
Fig. 2
the simplified diagram of an alternative embodiment of the invention.

Aus Fig. 1 geht ein Hydrauliksystem für ein nicht dargestelltes Fahrzeug hervor, welches einen Sammelbehälter (Sumpf) 10, ein grobmaschiges Vorfilter 11, eine durch einen Motor antreibbare unverstellbare Ladepumpe (Konstantpumpe) 12, eine durch einen Motor antreibbare Verstellpumpe (Hauptpumpe) 14, einen Schmierölkreis, wie zum Beispiel ein rechter und ein linker Endantriebsschmierölkreis 16, 18, einen Schmierölkreis 20 für einen Zapfwellenantrieb und einen Schmierölkreis 22 für einen Pumpenantrieb enthält. Die Verstellpumpe 14 ist beispielsweise eine Axialkolbenpumpe, die der Versorgung verschiedener Hydraulikfunktionen 15, wie beispielsweise Lenkung, Bremsen und Steuerventile, mit unter Druck stehender Flüssigkeit dient.1 shows a hydraulic system for a vehicle, not shown, which has a collecting tank (sump) 10, a coarse-mesh pre-filter 11, an immovable charging pump (constant pump) 12 which can be driven by a motor, and a variable displacement pump (main pump) 14 which can be driven by a motor, a lubricating oil circuit, such as right and left driveline lubricating oil circuits 16, 18, a lubricating oil circuit 20 for a PTO and a lubricating oil circuit 22 for a pump drive. The variable displacement pump 14 is, for example, an axial piston pump that serves to supply various hydraulic functions 15, such as steering, brakes and control valves, with liquid under pressure.

Ein hydraulischer Steuerkreis 28 erhält von der Ladepumpe 12 und einem nachgeschalteten Filterkreis 30 Hydraulikflüssigkeit und verteilt diese auf die Hauptpumpe 14 und den Schmierölkreis 16 - 22. Der Filterkreis 30 enthält ein Filter 32, ein Rückschlagventil 34, (wahlweise) ein Sieb 36 und ein Filterbypaßventil 38. Durch die Leitung 44 wird Hydraulikflüssigkeit von der Ladepumpe 12 zum Eingang des Ventils 38 und zur Eingangsseite des Filters 32 geleitet. Die Ausgangsseite des Filters 32 steht über ein Rückschlagventil 34 und die Leitungen 46 und 48 mit dem Eingang der Hauptpumpe 14 und über die Abtastleitung 49 mit einer Steuerkammer in Verbindung, die sich auf der Seite des Ventils 38 befindet, an der auch eine Rückstellfeder angreift. Ein erster Ausgang des Ventils 38 ist über das (wahlweise) Sieb 36 mit der Leitung 46 verbunden. Ein zweiter Ausgang des Ventils 38 ist über die Leitung 50 mit dem Sammelbehälter 10 verbunden. Die Abtastleitung 54 verbindet die Leitung 44 mit dem druckempfindlichen Steueranschluß des Ventils 38. Die Leitung 56 verbindet einen dritten Ausgang des Ventils 38 mit einem druckempfindlichen Schalter 58, der vorzugsweise eine Anzeigeeinrichtung, wie beispielsweise eine Glühlampe, auf dem Armaturenbrett auslöst, wenn die Leitung 56 unter Druck steht.A hydraulic control circuit 28 receives hydraulic fluid from the charge pump 12 and a downstream filter circuit 30 and distributes this to the main pump 14 and the lubricating oil circuit 16-22. The filter circuit 30 contains a filter 32, a check valve 34, (optionally) a strainer 36 and a filter bypass valve 38. Hydraulic fluid is passed through line 44 from the charge pump 12 to the inlet of the valve 38 and to the inlet side of the filter 32. The output side of the filter 32 is connected via a check valve 34 and the lines 46 and 48 to the input of the main pump 14 and via the scanning line 49 to a control chamber which is located on the side of the valve 38 which is also attacked by a return spring. A first outlet of the valve 38 is connected to the line 46 via the (optional) sieve 36. A second outlet of the valve 38 is connected to the collecting container 10 via the line 50. The scan line 54 connects line 44 to the pressure sensitive control port of valve 38. Line 56 connects a third outlet of valve 38 to a pressure sensitive switch 58 which preferably triggers an indicator, such as a light bulb, on the dashboard when line 56 is pressurized.

Die Leitung 60 verbindet die Leitung 46 mit dem Eingang des Ventils 40. Ein erster Ausgang 53 des Ventils 40 steht über die Leitung 68 mit den Schmierölkreisen 20 und 22 in Verbindung. Ein zweiter Ausgang 55 steht über die Blende 78 und die Leitung 70 mit den Schmierölkreisen 16 und 18 in Verbindung. Der Kanal 52 verbindet einen dritten Ausgang 57 des Ventils 40 mit dem Eingang der Ladepumpe 12. Durch die Abtastleitung 72 wird der Eingangsdruck der Hauptpumpe 14 an ein Ende des Schiebers oder Ventilteils 41 des Ventils 40 angelegt, während das andere Ende des Schiebers oder Ventilteils 41 durch eine Feder 43 vorgespannt und über die Blende 76 und die Leitung 74 an die Leitung 70 angeschlossen ist.Line 60 connects line 46 to the inlet of valve 40. A first outlet 53 of valve 40 is connected via line 68 to lubricating oil circuits 20 and 22. A second outlet 55 is connected to the lubricating oil circuits 16 and 18 via the orifice 78 and the line 70. Channel 52 connects a third outlet 57 of valve 40 to the inlet of charge pump 12. Through sense line 72, the inlet pressure of main pump 14 is applied to one end of spool or valve member 41 of valve 40 while the other end of spool or valve member 41 biased by a spring 43 and connected to the line 70 via the diaphragm 76 and the line 74.

Anfänglich wird das Öl durch das Vorfilter 11 von der Ladepumpe 12 angesaugt. Von dort wird es zum Filterkreis 30 gepumpt. In dem Filterkreis 30 wird die Flüssigkeit wahlweise entweder durch das Ölfilter 32 und das Rückschlagventil 34, welches ein Auslaufen der sich anschliessenden Leitungen bei einem Filterwechsel verhindert, oder durch das Filterbypaßventil 38 geleitet. Der Schalter 58 gibt bei 3,0 bar ein Anzeigesignal aus, welches meldet, daß nahezu die Bypaßbedingung erreicht ist, derzufolge Bypaßöl nur zugelassen wird, wenn die Druckdifferenz über dem Filter 32 einen Wert von 5 bar erreicht. Das Bypaßöl wird durch ein 100-Mikron-Sieb 36 geleitet und folgt dann dem gleichen Weg, den es unter normalen Bedingungen beim Durchtritt durch das Filter 32 eingenommen hätte.Initially, the oil is drawn through the pre-filter 11 by the charge pump 12. From there it is pumped to the filter circuit 30. In the filter circuit 30, the liquid is either passed through the oil filter 32 and the check valve 34, which prevents the connecting lines from leaking when changing the filter, or through the filter bypass valve 38. The switch 58 outputs a display signal at 3.0 bar, which signals that the bypass condition has almost been reached, according to which bypass oil is only permitted when the pressure difference across the filter 32 reaches a value of 5 bar. The bypass oil is passed through a 100 micron sieve 36 and then follows the same path that it would have taken under normal conditions as it passed through the filter 32.

Das Öl fließt dann zu einem Punkt, von wo aus es im Bedarfsfall zum Eingang der Hauptpumpe 14 oder, falls keine Ölanforderung von der Hauptpumpe 14 vorliegt, zu dem Ladedruck-Prioritäts-Abzweig-Ventil 40 fließt. Durch das Ventil 40 fließt kein Öl, wenn der Druck am Eingang der Hauptpumpe 14 nicht 0,5 bar übersteigt. Ab 0,5 bar stellt sich das Ventil 40 so ein, daß es Öl zu den Schmierölkreisen 20 und 22 leitet. Wenn diese Schmierölkreise einen Druck von 1,0 bar erreichen, öffnet sich das Ventil 40 weiter und eine Kühlölströmung wird zu den Schmierölkreisen 16 und 18 geleitet. Erreicht der Druck an dem Ventil 40 einen Wert von 1,5 bar, so leitet dieses einen Teil der von der Ladepumpe 12 und dem Filterkreis 30 kommenden, in das Ventil 40 eintretenden Ölmenge zu dem Kanal 52, über welchen das Öl zurück zu der Ansaugseite der Ladepumpe 12 geführt wird. Um die Wechselwirkung zwischen dem Ventil 40 und der Ladepumpe 12 gering zu halten, wird die mit der Feder beaufschlagte Seite des Schiebers 41 über eine Leitung 74 und eine Blende 76 mit der Leitung 70 verbunden. Zur Verbesserung der Filterbenutzung und der Kühlung sollte bei maximaler Motordrehzahl ein hoher Anteil des Ladeöls durch den Schmierölkreis fließen.The oil then flows to a point from where it flows to the input of the main pump 14 if necessary or, if there is no oil request from the main pump 14, to the boost pressure priority branch valve 40. No oil flows through the valve 40 if the pressure at the inlet of the main pump 14 does not exceed 0.5 bar. From 0.5 bar, the valve 40 adjusts itself so that it directs oil to the lubricating oil circuits 20 and 22. When these lubricating oil circuits reach a pressure of 1.0 bar, the valve 40 opens further and a cooling oil flow is directed to the lubricating oil circuits 16 and 18. If the pressure at the valve 40 reaches a value of 1.5 bar, this directs a part of the oil quantity coming from the charge pump 12 and the filter circuit 30 and entering the valve 40 to the channel 52, via which the oil returns to the suction side the charge pump 12 is guided. In order to keep the interaction between the valve 40 and the charge pump 12 low, the spring-loaded side of the slide 41 is connected to the line 70 via a line 74 and an orifice 76. To improve filter usage and cooling, a high proportion of the charging oil should flow through the lubricating oil circuit at maximum engine speed.

Da die Ladepumpe 12 bezüglich des maximalen Bedarfs der Hauptpumpe 14 überdimensioniert ist, steht zu jeder Zeit eine Durchflußmenge für den Schmierölkreis zur Verfügung. Es wird ferner angenommen, daß die Hauptpumpe 14 selten mit voller Förderleistung arbeitet, so daß die für die Schmierölkreise zur Verfügung stehende Ölmenge mehr als ausreichend sein sollte. Die Bypaßfunktion des Ladedruck-Prioritäts-Abzweig-Ventils 40, durch die überschüssiges Öl zurück zu dem Ladepumpeneingang geleitet wird, ist dafür bestimmt, die Durchflußmenge von ungefiltertem Öl durch das Ölfilter 11 möglichst gering zu halten. Dies ist wünschenswert, damit das System mit einer Ladepumpe 12 betrieben werden kann, die für 2,3 l/s bei hoher Leerlaufdrehzahl ausgelegt ist und dennoch bei den meisten Betriebsbedingungen lediglich 1,0 l/s des ungefilterten Öls aufnimmt.Since the charge pump 12 is oversized with regard to the maximum demand of the main pump 14, a flow rate for the lubricating oil circuit is available at all times. It is also believed that the main pump 14 rarely operates at full capacity, so the amount of oil available to the lubricating oil circuits should be more than sufficient. The bypass function of the boost priority branch valve 40, through which excess oil is returned to the charge pump inlet, is intended to keep the flow rate of unfiltered oil through the oil filter 11 as low as possible. This is desirable in order for the system to operate with a charge pump 12 which is designed for 2.3 l / s at high idling speed and yet only absorbs 1.0 l / s of the unfiltered oil under most operating conditions.

Bei der tiefsten zu erwartenden Motordrehzahl von 600 Umdrehungen pro Minute muß die von der Ladepumpe 12 erzeugte Durchflußmenge ausreichen, um die Hauptpumpe 14 bei voller Förderleistung zu versorgen.At the lowest expected engine speed of 600 revolutions per minute, the flow rate generated by the charge pump 12 must be sufficient to supply the main pump 14 at full delivery rate.

Die Fig. 2 zeigt eine alternative Ausgestaltung der Erfindung, bei der jedoch die Hydraulikkreisleitung 64 den Ausgang 59 des Ventils 40' über die Leitung 80 und die Blende 81 mit dem Eingang der Ladepumpe 12 verbindet. Ferner verbindet die Leitung 62 einen zweiten Eingang 61 des Ventils 40' mit dem Ausgang der Ladepumpe 12. Das Ventil 40' weist eine erste Position, in der alle Anschlüsse blockiert sind, eine zweite Position, in der der Eingang 51 mit dem Ausgang 53 verbunden ist und eine dritte Position auf, in der der Eingang 51 mit dem Ausgang 53 und der Eingang 61 mit dem Ausgang 59 verbunden ist. Schließlich ist in der Ausgestaltung gemäß Fig. 2 der Ausgang 53 über die Leitung 66 mit den Leitungen 68 und 70 verbunden. In der Leitung 68 ist ein Rückschlagventil 42 angeordnet, um einen Einwegflüssigkeitsstrom zu den Funktionen 20 und 22 zu ermöglichen und der Strömung zu den Funktionen 16 und 18 die Priorität einzuräumen.2 shows an alternative embodiment of the invention, in which, however, the hydraulic circuit line 64 connects the outlet 59 of the valve 40 ′ via the line 80 and the orifice 81 to the inlet of the charge pump 12. Furthermore, line 62 connects a second inlet 61 of valve 40 'to the outlet of charge pump 12. Valve 40' has a first position in which all connections are blocked, a second position in which inlet 51 is connected to outlet 53 and a third position in which the input 51 is connected to the output 53 and the input 61 is connected to the output 59. Finally, in the embodiment according to FIG. 2, the output 53 is connected to the lines 68 and 70 via the line 66. A check valve 42 is disposed in line 68 to allow one-way fluid flow to functions 20 and 22 and to give priority to flow to functions 16 and 18.

Während eines Kaltwetterbetriebes liefert die Ladepumpe 12 entweder über das Filter 32 oder, was wahrscheinlicher ist, durch das Filterbypaßventil 38 Öl an den Hauptpumpeneingang. Während dieses anfänglichen Betriebes übersteigt der Ladedruck wahrscheinlich den Wert von 1,5 bar, der erforderlich ist, um überschüssige Ladeförderleistung über den durch das Ventil 40' gebildeten Bypaß zu dem Eingang der Ladepumpe 12 zu leiten. Vorzugsweise ist der Kreis 28 ungefähr in gleicher Entfernung zum Hauptpumpeneingang und zum Ladepumpeneingang angeordnet, und die Bypaßleitung 80 enthält eine Beschränkung 81, so daß die Hauptpumpe 14 immer noch die Priorität genießt. Wird durch die Hauptpumpe 14 kein Öl angefordert, so wird die Ladedurchflußmenge an die Ladepumpe 12, was zum Aufwärmen des Hydraulikkreises beiträgt, sowie zu den Schmierölkreisen 16 - 20 weiter geleitet.During a cold weather operation, charge pump 12 supplies oil to the main pump inlet either through filter 32 or, more likely, through filter bypass valve 38. During this initial operation, the boost pressure is likely to exceed 1.5 bar required to transfer excess boost flow through the bypass formed by valve 40 'to the inlet to direct the charge pump 12. The circuit 28 is preferably located approximately equidistant from the main pump inlet and the charge pump inlet, and the bypass line 80 contains a restriction 81 so that the main pump 14 still enjoys priority. If no oil is requested by the main pump 14, the charge flow rate is passed on to the charge pump 12, which contributes to warming up the hydraulic circuit, and to the lubricating oil circuits 16-20.

Auch wenn die Erfindung lediglich an Hand zweier Ausführungsbeispiele beschrieben wurde, erschließen sich für den Fachmann im Lichte der vorstehenden Beschreibung viele verschiedenartige Alternativen, Modifikationen und Varianten, die unter die vorliegende Erfindung fallen. So sind beispielsweise die genannten Druckwerte und Durchflußmengen lediglich exemplarisch angegeben und können je nach Anwendungsfall durch andere Werte ersetzt werden.Even if the invention was only described on the basis of two exemplary embodiments, many different alternatives, modifications and variants which fall under the present invention will become apparent to the person skilled in the art in the light of the above description. For example, the pressure values and flow rates mentioned are only given as examples and can be replaced by other values depending on the application.

Claims (11)

  1. Hydraulic system for the supply of at least one first hydraulic function (15) by a main pump (14) which is charged by a charge pump (12), wherein an excess partial fluid stream of the charge pump (12) supplies at least one second hydraulic function (16-22), characterised in that a priority valve (40, 40') is connected to the charge pump (12), the main pump input and the second hydraulic function (16-22) and selectively conducts excess fluid not used up by the main pump, from the charge pump (12) to the second hydraulic function (16-22) and an input of the charge pump (12).
  2. Hydraulic system according to claim 1, characterised in that the output of the charge pump (12) is connected with the interposition of a filter (32) to the input of the main pump (14) and an input (51) of the priority valve (40, 40') and in that the priority valve (40, 40') contains a first output (53) connected to the second hydraulic function (16-22) and a valve portion (41, 41') which is movable as a function of the fluid pressure applied to the input of the main pump (14) and which in a first position blocks all inputs and outputs and in a second position connects the input (51) to the first output (53).
  3. Hydraulic system according to claim 2, characterised in that by spring means (43) the valve portion (41, 41') is biased into its first position, and by the fluid pressure prevailing at the input of the main pump (14) the valve portion (41, 41') is biased into its second position.
  4. Hydraulic system according to claim 2 or 3, characterised in that the priority valve (40) contains a second output (55) connected to a third hydraulic function (16, 18) and in that the valve portion (41) in a third position connects the input (51) to the first output (53) and/or second output (55).
  5. Hydraulic system according to any of claims 2 to 4, characterised in that a throttle point (78) is provided in the connecting pipe (68) between the first output (53) and the second hydraulic function (20, 22) and/or in the connecting pipe (70) between a second output (55) and a third hydraulic function (16, 18).
  6. Hydraulic system according to any of claims 3 to 5, characterised in that the side of the valve portion (41, 41') which is acted upon by the spring element (43) is connected by a throttle point (76) to the input of the second or a third hydraulic function (16, 18; 20, 22).
  7. Hydraulic function according to any of claims 2 to 6, characterised in that the priority valve (40, 40') contains a further output (57, 59) connected to the input of the charge pump (12) and in that the valve portion (41, 41') in a further position connects the input (51) to the first output (53) and/or the second output (55) and/or the further output (57, 59).
  8. Hydraulic system according to claim 2 or 3, characterised in that the priority valve (40') contains a second input (61) connected to the input of the charge pump (12) and in that the valve portion (41') in the second position connects only the first input (51) to the first output (53) and in a third position connects the first input (51) to the first output (53) as well as the second input (61) to the second output (59).
  9. Hydraulic system according to any of claims 2 to 8, characterised in that the second hydraulic function contains a first lubricating oil circuit (16, 18) and a second lubricating oil circuit (20, 22) which are connected by a first pipe (70) and a second pipe (68) respectively to the first output (53) of the priority valve (40, 40'), and in that in the second pipe (68) is provided a non-return valve (42) which prevents flow through the second pipe (68) if the pressure in the first pipe (70) does not exceed a presettable value.
  10. Hydraulic system according to any of claims 2 to 9, characterised in that in the connecting pipe (80) between the input of the charge pump (12) and the output of the priority valve (40, 40'), which output is connected to this input, is provided a throttle point (81).
  11. Hydraulic system according to any of claims 1 to 10, characterised in that a filter (32) and a filter bypass valve (38) are provided, wherein the filter bypass valve (38) conducts at least a portion of the fluid stream past the filter (32) if the fluid pressure at the filter input exceeds a presettable value.
EP91103253A 1990-03-13 1991-03-05 Hydraulic system to supply a variable displacement pump Expired - Lifetime EP0446757B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US07/492,198 US5020324A (en) 1990-03-13 1990-03-13 Charge flow priority circuit
US492198 1990-03-13

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EP0446757A1 EP0446757A1 (en) 1991-09-18
EP0446757B1 true EP0446757B1 (en) 1994-08-24

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EP91103253A Expired - Lifetime EP0446757B1 (en) 1990-03-13 1991-03-05 Hydraulic system to supply a variable displacement pump

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US (1) US5020324A (en)
EP (1) EP0446757B1 (en)
JP (1) JP3070962B2 (en)
AT (1) ATE110444T1 (en)
CA (1) CA2038112C (en)
DE (1) DE59102593D1 (en)
ES (1) ES2057630T3 (en)
MX (1) MX172032B (en)

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EP3516272B1 (en) 2016-09-26 2021-12-01 hofer powertrain innovation GmbH Hydraulic system for supplying i.a. clutch actuators
DE102011115805B4 (en) 2011-10-12 2021-12-09 Robert Bosch Gmbh Hydraulic system with a main pump and a charge pump

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Publication number Priority date Publication date Assignee Title
DE102011115805B4 (en) 2011-10-12 2021-12-09 Robert Bosch Gmbh Hydraulic system with a main pump and a charge pump
CN104533766A (en) * 2014-12-03 2015-04-22 安徽博一流体传动股份有限公司 Hydraulic plunger pump with various variable control functions
EP3516272B1 (en) 2016-09-26 2021-12-01 hofer powertrain innovation GmbH Hydraulic system for supplying i.a. clutch actuators

Also Published As

Publication number Publication date
CA2038112C (en) 1994-08-16
JPH04211704A (en) 1992-08-03
ES2057630T3 (en) 1994-10-16
JP3070962B2 (en) 2000-07-31
DE59102593D1 (en) 1994-09-29
US5020324A (en) 1991-06-04
MX172032B (en) 1993-11-29
ATE110444T1 (en) 1994-09-15
EP0446757A1 (en) 1991-09-18
CA2038112A1 (en) 1991-09-14

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