EP2069641B1 - Hydrostatic gear mechanism - Google Patents

Hydrostatic gear mechanism Download PDF

Info

Publication number
EP2069641B1
EP2069641B1 EP07785900A EP07785900A EP2069641B1 EP 2069641 B1 EP2069641 B1 EP 2069641B1 EP 07785900 A EP07785900 A EP 07785900A EP 07785900 A EP07785900 A EP 07785900A EP 2069641 B1 EP2069641 B1 EP 2069641B1
Authority
EP
European Patent Office
Prior art keywords
port
pressure
pressure medium
pump arrangement
cylinder
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.)
Not-in-force
Application number
EP07785900A
Other languages
German (de)
French (fr)
Other versions
EP2069641A1 (en
Inventor
Jörg Dantlgraber
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.)
Robert Bosch GmbH
Original Assignee
Robert Bosch GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Robert Bosch GmbH filed Critical Robert Bosch GmbH
Publication of EP2069641A1 publication Critical patent/EP2069641A1/en
Application granted granted Critical
Publication of EP2069641B1 publication Critical patent/EP2069641B1/en
Not-in-force legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

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
    • F15B7/00—Systems in which the movement produced is definitely related to the output of a volumetric pump; Telemotors
    • F15B7/001—With multiple inputs, e.g. for dual 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
    • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/08—Servomotor systems without provision for follow-up action; Circuits therefor with only one servomotor
    • 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
    • F15B7/00—Systems in which the movement produced is definitely related to the output of a volumetric pump; Telemotors
    • F15B7/005—With rotary or crank input
    • F15B7/006—Rotary pump input
    • 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
    • F15B2211/20561—Type of pump reversible
    • 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
    • F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/265—Control of multiple pressure sources
    • 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
    • F15B2211/41—Flow control characterised by the positions of the valve element
    • F15B2211/413—Flow control characterised by the positions of the valve element the positions being continuously variable, e.g. as realised by proportional valves
    • 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
    • F15B2211/428—Flow control characterised by the type of actuation actuated by fluid pressure
    • 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
    • F15B2211/46—Control of flow in the return line, i.e. meter-out 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
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/705—Output members, e.g. hydraulic motors or cylinders or control therefor characterised by the type of output members or actuators
    • F15B2211/7051—Linear output members
    • F15B2211/7053—Double-acting output members

Definitions

  • the invention relates to a hydrostatic transmission with a differential cylinder and a pump arrangement and the other features according to the preamble of patent claim 1 or according to the preamble of claim 2.
  • a hydrostatic transmission is understood to mean the combination of a hydraulic pump (primary part) with a hydraulic motor (secondary part), in the simplest case with a hydraulic cylinder whose displacer spaces are ideally connected without flow resistance during operation.
  • Such hydrostatic transmissions require due to the external leakage of the hydraulic-mechanical converter means that realizes the supply of pressure medium in the transmission to compensate for these losses and to maintain the functionality of the transmission. By this means must be prevented in particular, that form cavitation phenomena in the cylinder chambers.
  • a transmission with double-sided clamping of the output motor (secondary unit) proves that both the drive dynamics and the load rigidity over conventional transmissions with open hydraulic circuits is substantially improved by such a clamping.
  • variable displacement pumps are independently adjustable and are driven by a common motor, wherein one of the variable displacement pumps an annular space of the differential cylinder is connected to a bottom-side cylinder chamber, while the other variable displacement pump supplies the cylinder chamber from a tank with pressure medium.
  • the two variable displacement pumps are controlled via a control unit such that, for example, when the hydraulic cylinder is extended, the cylinder chamber is supplied with a little more pressure medium than is required for the extension movement, while the annular space is supplied with an excess quantity when the cylinder is retracted.
  • a control unit such that, for example, when the hydraulic cylinder is extended, the cylinder chamber is supplied with a little more pressure medium than is required for the extension movement, while the annular space is supplied with an excess quantity when the cylinder is retracted.
  • a counter-holding pressure is built up in the other cylinder space, so that the piston of the differential cylinder is clamped on both sides.
  • a hydrostatic transmission is known in which a differential cylinder is supplied via two constant-displacement pumps driven by a common motor with pressure medium.
  • Pressure medium can be conveyed from one of the cylinder chambers of the hydraulic cylinder into the respective other pump chamber via one of the constant-displacement pumps, while the second pump of the primary part supplies the bottom-side cylinder chamber with pressure medium from a hydrostatic accumulator.
  • This memory can also be connected directly to the cylinder chambers of the hydraulic cylinder to compensate for leakage losses and clamp the hydraulic cylinder on both sides.
  • the invention has for its object to provide a hydrostatic transmission in which a bias of a differential cylinder with low device technology and control engineering effort is possible.
  • the hydrostatic transmission according to claim 1 has a differential cylinder with a bottom-side cylinder space to which a flow line is connected, and with a piston rod side cylinder space to which a return line is connected, and a pump assembly.
  • a first connection and a second connection of the pump arrangement to the supply line and a third connection of the pump arrangement to the return line are connected.
  • Pressure fluid can be conveyed from a decreasing cylinder space of the differential cylinder or from a pressure medium reservoir into a cylinder space that enlarges such that the differential cylinder is hydraulically prestressed.
  • a biasing valve is connected to the return line, via which a throttle cross-section can be opened to the accumulator and which is acted upon by the pressure which is present in the flow line in the opening direction and by a biasing spring in the closing direction. If the pump arrangement is now set so that the pressure medium flow removed therefrom from the decreasing cylinder space is always smaller than the pressure medium volume flow displaced from the decreasing cylinder space, the excess pressure fluid volume flow component must be displaced via the throttle cross section to the pressure medium reservoir, whereby a biasing pressure is built up.
  • the hydrostatic transmission according to claim 2 also has a differential cylinder with a bottom-side cylinder space to which a flow line is connected, and with a piston rod-side cylinder space to which a return line is connected, and a pump assembly.
  • a first connection and a second connection of the pump arrangement to the supply line and a third connection of the pump arrangement to the return line are connected.
  • Pressure fluid can be conveyed from a decreasing cylinder chamber of the differential cylinder or from a pressure medium reservoir into a cylinder chamber that enlarges such that the differential cylinder is hydraulically preloaded.
  • the base-side cylinder chamber of the differential cylinder is assigned a preload valve via which a throttle cross-section can be opened, this preload valve being arranged between a fourth connection of the pump arrangement and the pressure medium accumulator and acted upon by the pressure in the return line in the opening direction and by a pretensioning spring in the closing direction.
  • a first non-return valve opening toward the fourth connection and a second non-return valve opening towards the fourth connection are advantageously arranged between the accumulator and the fourth connection of the pump arrangement.
  • equal delivery volumes are conducted via the first connection and the second connection of the pump arrangement. It is preferable for obtaining the bias voltage when the area ratio of the differential cylinder is set smaller than 2.
  • each of the cylinder chambers is assigned a preload valve.
  • the pump assembly is particularly simple if it has two synchronously adjustable pumps.
  • a split-flow variable displacement pump, a variable-speed split-flow variable displacement pump and a reversible conveying direction a so-called floating cup variable displacement pump with synchronous adjustment (see DE 10 2006 003 122 ) or a floating cup fixed displacement pump with variable speed and reversible conveying direction or similar pump designs are used.
  • the accumulator can be designed as a tank or as a prestressed low-pressure accumulator.
  • FIG. 1 a hydrostatic transmission 1 with a primary part 2 and a secondary part 4 is shown.
  • the latter is formed by a differential cylinder 6, the differential piston 8 has the active surfaces A 1 and A 2 .
  • the differential piston 8 divides the differential cylinder into a bottom-side cylinder chamber 10 with the cross-sectional area A 1 and a piston rod-side annular space 12 with the annular surface A 2 .
  • the secondary part 4 is at the in FIG. 1 illustrated embodiment by two synchronously adjustable variable displacement pumps 14, 16 which are driven by a common motor 18. In the described embodiment, it is assumed that the variable displacement pumps 14, 16 have the same delivery volume. According to the invention, the differential piston 8 is then designed so that the end face ratio A 1 / A 2 ⁇ 2.
  • the cylinder chamber 10 is connected via a branching pressure line 22 with the two in FIG. 1 overhead connections P 1 and P 2 of the two variable displacement pumps 14, 16 connected. These connections are hereinafter referred to as pressure ports although they act as retraction ports when retracting the differential piston 8, wherein then also the pressure line 22 is a suction line.
  • the annular space 12 of the differential cylinder 6 is connected via a return line 24 with a suction port S 2 of the variable displacement pump 14.
  • a suction connection S 1 of the further variable displacement pump 16 is connected to the tank 20 via a suction line 26 and a non-return valve 28 which closes in the direction of the tank 20.
  • the suction line 26 is over a Delivery line 30 and another in the direction of the tank 20 blocking check valve 32 connected to the pressure line 22.
  • the biasing valve 36 has a slide 38 which is acted upon in the direction of its closed position by the force of a biasing spring 40 and in the direction of increasing the opening cross section by a control pressure, which is tapped via a bias control line 42 from the pressure line 22.
  • a control pressure which is tapped via a bias control line 42 from the pressure line 22.
  • a further tank line 46 in which a further biasing valve 48 is arranged, whose construction is equal to that of the biasing valve 36.
  • the further biasing valve 48 has a slider 50 with a control edge 52 which is biased by a biasing spring 54 in its illustrated closed position and is acted upon in the direction of increasing the throttle cross section of the control pressure in a control line 56 which branches off from the return line 24. Accordingly, the throttle area of the biasing valve 48 is determined by the pressure in the return line 24.
  • the motor 18 is controlled via a pump control, not shown, such that both variable displacement pumps 14, 16 convey pressure medium via the pressure line 22 into the cylinder chamber 10.
  • both variable displacement pumps 14, 16 convey pressure medium via the pressure line 22 into the cylinder chamber 10.
  • out of the annular space 12 displaced pressure medium via the return line 24 to the suction port S 2 of the variable displacement pump 14 is performed.
  • the additional, required to fill the cylinder chamber 10 pressure medium quantity is sucked by the variable displacement pump 16 via the suction port S 1 , the suction line 26, the opening check valve 28 from the tank 20.
  • the biasing valve 36 is still closed and the pressure in the cylinder chamber 10 increases relatively quickly.
  • the throttle cross-section of the biasing valve 36 is then turned against the force of the biasing spring 40, so that the excess amount of pressure medium is conveyed to the tank 20 and the differential cylinder 6 is biased according to the throttle cross-section.
  • This bias pressure decreases with increasing pressure in the pressure line 22. While this extension movement, the further biasing valve 48 remains closed because the pressure in the return line 24 is not sufficient to open this against the force of the biasing spring 54.
  • the extension speed is set via the synchronous pivoting of the two variable displacement pumps 14, 16.
  • variable displacement pumps For retracting the differential cylinder 6, the variable displacement pumps are pivoted so that the conveying direction is reversed, so that via the variable displacement 14 pressure medium is conveyed into the annular space 12.
  • the two "pressure ports" P 1 and P 2 of the two variable displacement pumps 14, 16 then act as suction ports, via which the pressure medium from the cylinder chamber 10 the two variable displacement pumps 14, 16 is supplied.
  • the variable displacement pump 16 then promotes via the port acting as a pressure connection S 1 pressure medium in the suction line 26 and from there via the opening another check valve 32 and the delivery line 30 back to the suction line 22.
  • the existing due to the prescribed area ratios excess portion of the pressure medium is on the another tank line 46 and the further biasing valve 48 opening at a pressure build-up in the return line 24 to the tank 20 toward discharged.
  • the set throttle cross-section and thus the bias of the differential cylinder 6 depends on the pressure in the return line 24, so that the throttle cross section is increased with increasing pressure in the annular space 12 and thus decreases the bias.
  • the exemplary embodiment is not restricted to the fact that both pumps 14, 16 convey with the same delivery volume. In principle, no synchronous control is required, these pumps 14, 16 could also be controlled independently of each other. For unequal flow rates and the displaced pressure medium flow should always be slightly larger than the pressure medium flow supplied to the pump, so that the excess amount can be discharged through at least one biasing valve to the tank and according to the setting of the throttle cross section, a bias occurs.
  • FIG. 2 shows a corresponding embodiment, in which instead of the two driven by a common motor shaft variable displacement pumps 14, 16, a so-called split-flow variable displacement pump 58 can be used.
  • split-flow variable displacement pumps 58 may, for example, be designed in axial piston construction, wherein the multiplicity of axial pistons are divided into two equal parts in order to produce two separate pressure medium volume flows To provide size.
  • the multiplicity of axial pistons are divided into two equal parts in order to produce two separate pressure medium volume flows To provide size.
  • FIG. 2 used symbol of such a pump would then suck a part of the axial piston (depending on the direction), for example pressure medium through the suction ports S 1 and S 2 and then promote the two separate pressure ports P 1 and P 2 in the pressure line 22.
  • the structure of the hydrostatic transmission is identical to those of FIG. 1 , so that further explanations are dispensable.
  • variable displacement pumps can also similar to the prior art according to the DE 103 42 102 A1 two constant-displacement pumps driven by a common motor are used, in which case the motor must be reversible in its direction of rotation and adjustable in its rotational speed.
  • so-called "floating-cup pumps” have proven to be particularly suitable, which are based on a development of the Applicant and which can be designed as a variable displacement pump with synchronous adjustment or as a fixed displacement pump with variable and reversible speed.
  • floating cup pumps are for example in the DE 10 2006 003 122 the applicant described.

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Control Of Fluid Gearings (AREA)

Abstract

A hydrostatic gear mechanism having a drive motor is disclosed, the inflow and outflow connections of which are connected to a pump arrangement, via which pressure medium can be conveyed out of a diminishing pressure space of the output motor or out of a pressure-medium accumulator into an expanding pressure space in such a way that the output motor is prestressed hydraulically. A prestressing valve device, via which a throttling cross section to the pressure accumulator can be opened, is provided in the return line from the diminishing pressure space. Here, the delivery volume of the pump arrangement is set in such a way that the volumetric flow of pressure medium which is fed to the pump arrangement is smaller than the volumetric flow of pressure medium which is expelled from the diminishing pressure space.

Description

Die Erfindung betrifft ein hydrostatisches Getriebe mit einem Differentialzylinder und einer Pumpenanordnung sowie den sonstigen Merkmalen gemäß dem Oberbegriff des Patentanspruchs 1 oder gemäß dem Oberbegriff des Patentanspruchs 2.The invention relates to a hydrostatic transmission with a differential cylinder and a pump arrangement and the other features according to the preamble of patent claim 1 or according to the preamble of claim 2.

Unter einem hydrostatischem Getriebe versteht man die Kombination einer Hydropumpe (Primärteil) mit einem Hydromotor (Sekundärteil), im einfachsten Fall mit einem Hydrozylinder, dessen Verdrängerräume im Betrieb idealerweise strömungswiderstandsfrei verbunden sind. Derartige hydrostatische Getriebe bedürfen aufgrund der externen Leckagen der hydraulisch-mechanischen Wandler einer Einrichtung, die die Zuführung von Druckmittel in das Getriebe realisiert, um diese Verluste auszugleichen und die Funktionsfähigkeit des Getriebes zu erhalten. Durch diese Einrichtung muß insbesondere verhindert werden, dass sich in den Zylinderräumen Kavitationserscheinungen ausbilden. Als besonders vorteilhaft erweist sich ein Getriebe mit beidseitiger Einspannung des Abtriebsmotors (Sekundäreinheit), wobei durch eine derartige Einspannung sowohl die Antriebsdynamik als auch die Laststeifigkeit gegenüber herkömmlichen Getrieben mit offenen Hydraulikkreisläufen wesentlich verbessert ist.A hydrostatic transmission is understood to mean the combination of a hydraulic pump (primary part) with a hydraulic motor (secondary part), in the simplest case with a hydraulic cylinder whose displacer spaces are ideally connected without flow resistance during operation. Such hydrostatic transmissions require due to the external leakage of the hydraulic-mechanical converter means that realizes the supply of pressure medium in the transmission to compensate for these losses and to maintain the functionality of the transmission. By this means must be prevented in particular, that form cavitation phenomena in the cylinder chambers. Particularly advantageous is a transmission with double-sided clamping of the output motor (secondary unit) proves that both the drive dynamics and the load rigidity over conventional transmissions with open hydraulic circuits is substantially improved by such a clamping.

In der DE 40 08 792 A1 ist ein hydrostatisches Getriebe offenbart, bei dem ein Differentialzylinder über zwei Verstellpumpen mit Druckmittel versorgt wird. Die Verstellpumpen sind unabhängig voneinander verstellbar und werden von einem gemeinsamen Motor angetrieben, wobei über eine der Verstellpumpen ein Ringraum des Differentialzylinders mit einem bodenseitigen Zylinderraum verbunden ist, während die andere Verstellpumpe den Zylinderraum aus einem Tank mit Druckmittel versorgt.In the DE 40 08 792 A1 is a hydrostatic transmission disclosed in which a differential cylinder is supplied via two variable displacement pumps with pressure medium. The variable displacement pumps are independently adjustable and are driven by a common motor, wherein one of the variable displacement pumps an annular space of the differential cylinder is connected to a bottom-side cylinder chamber, while the other variable displacement pump supplies the cylinder chamber from a tank with pressure medium.

Die beiden Verstellpumpen werden über eine Steuereinheit derart angesteuert, dass beispielsweise beim Ausfahren des Hydrozylinders der Zylinderraum mit etwas mehr Druckmittel versorgt wird als zur Ausfahrbewegung erforderlich ist, während beim Einfahren des Zylinders der Ringraum mit einer Überschußmenge versorgt wird. Durch diese Steuerung wird im jeweils anderen Zylinderraum ein Gegenhaltedruck aufgebaut, so dass der Kolben des Differentialzylinders beidseitig eingespannt ist. Nachteilig bei dieser Lösung ist, dass die Ansteuerung der beiden Verstellpumpen einen erheblichen vorrichtungstechnischen Aufwand erfordert.The two variable displacement pumps are controlled via a control unit such that, for example, when the hydraulic cylinder is extended, the cylinder chamber is supplied with a little more pressure medium than is required for the extension movement, while the annular space is supplied with an excess quantity when the cylinder is retracted. By this control, a counter-holding pressure is built up in the other cylinder space, so that the piston of the differential cylinder is clamped on both sides. The disadvantage of this solution is that the control of the two variable displacement pumps requires a considerable device complexity.

Aus der CA 605 046 ist ein hydrostatisches Getriebe bekannt, bei der ein Differentialzylinder über zwei von einem gemeinsamen Motor angetriebene Konstantpumpen mit Druckmittel versorgt wird. Über eine der Konstantpumpen kann Druckmittel aus einem der Zylinderräume des Hydrozylinders in den jeweils anderen Pumpenraum gefördert werden, während die zweite Pumpe des Primärteils den bodenseitigen Zylinderraum mit Druckmittel aus einem hydrostatischen Speicher versorgt. Dieser Speicher ist auch direkt mit den Zylinderräumen des Hydrozylinders verbindbar, um Leckageverluste auszugleichen und den Hydrozylinder beidseitig einzuspannen.From the CA 605 046 is a hydrostatic transmission is known in which a differential cylinder is supplied via two constant-displacement pumps driven by a common motor with pressure medium. Pressure medium can be conveyed from one of the cylinder chambers of the hydraulic cylinder into the respective other pump chamber via one of the constant-displacement pumps, while the second pump of the primary part supplies the bottom-side cylinder chamber with pressure medium from a hydrostatic accumulator. This memory can also be connected directly to the cylinder chambers of the hydraulic cylinder to compensate for leakage losses and clamp the hydraulic cylinder on both sides.

Auch bei dieser Lösung ist ein erheblicher vorrichtungstechnischer Aufwand zum Ansteuern der beiden Pumpen und zum Vorspannen des Hydrozylinders erforderlich.Also in this solution, a considerable device-technical effort for driving the two pumps and for biasing the hydraulic cylinder is required.

In der DE 103 42 102 A1 der Anmelderin ist ein hydrostatisches Getriebe offenbart, bei dem die Vorspannung des Hydrozylinders über eine zusätzliche Ladeeinrichtung mit zwei von einem gemeinsamen Lademotor angetriebenen Ladepumpen erfolgt, wobei das zum Ein- oder Ausfahren des Hydrozylinders erforderliche Druckmittel über zwei gekoppelte, von einem gemeinsamen Motor angetriebene Konstantpumpen gefördert wird.In the DE 103 42 102 A1 The applicant is a hydrostatic transmission disclosed in which the bias of the hydraulic cylinder via an additional charging device with two driven by a common loading motor charge pump, wherein the required to extend or retract the hydraulic cylinder pressure medium via two coupled, driven by a common motor constant pumps promoted becomes.

Auch bei dieser Lösung ist ein hoher vorrichtungstechnischer Aufwand zum Vorspannen und Betätigen des Abtriebsmotors (Hydrozylinders) erforderlich.Also in this solution, a high device-technical effort for preloading and pressing the output motor (hydraulic cylinder) is required.

Weitere hydrostatische Getriebe mit einem Differentialzylinder und einer Pumpenanordnung sind aus der JP 2002 021807 A bekannt, die zwei Ausführungen, bei denen die Pumpenanordnung zwei Konstantpumpen umfasst, und eine weitere Ausführung zeigt, bei der die Pumpenanordnung eine Konstantpumpe und eine Verstellpumpe umfasst. Bei einem hydrostatischen Getriebe gemäß der DE 197 16 081 C1 besteht die einen Differentialzylinder betätigende Pumpenanordnung wiederum aus zwei Konstantpumpen.Other hydrostatic transmission with a differential cylinder and a pump assembly are from the JP 2002 021807 A known, the two embodiments in which the pump assembly comprises two constant displacement pumps, and a further embodiment, in which the pump assembly comprises a fixed displacement pump and a variable displacement pump. In a hydrostatic transmission according to the DE 197 16 081 C1 the differential cylinder actuated pump arrangement again consists of two constant pumps.

Demgegenüber liegt der Erfindung die Aufgabe zugrunde, ein hydrostatisches Getriebe zu schaffen, bei dem eine Vorspannung eines Differentialzylinders mit geringem vorrichtungstechnischen und regelungstechnischen Aufwand ermöglicht ist.In contrast, the invention has for its object to provide a hydrostatic transmission in which a bias of a differential cylinder with low device technology and control engineering effort is possible.

Diese Aufgabe wird durch ein hydrostatisches Getriebe mit den Merkmalen des Patentanspruchs 1 und durch ein hydrostatisches Getriebe mit den Merkmalen des Patentanspruchs 2 gelöst.This object is achieved by a hydrostatic transmission having the features of patent claim 1 and by a hydrostatic transmission having the features of patent claim 2.

Das hydrostatische Getriebe gemäß Patentanspruch 1 besitzt einen Differentialzylinder mit einem bodenseitigen Zylinderraum, an den eine Vorlaufleitung angeschlossen ist, und mit einem kolbenstangenseitigen Zylinderraum, an den eine Rücklaufleitung angeschlossen ist, und eine Pumpenanordnung. Dabei sind ein erster Anschluss und ein zweiter Anschluss der Pumpenanordnung mit der Vorlaufleitung und ein dritter Anschluss der Pumpenanordnung mit der Rücklaufleitung verbunden. Druckmittel ist aus einem sich verkleinernden Zylinderraum des Differentialzylinders oder aus einem Druckmittelspeicher in einen sich vergrößernden Zylinderraum derart förderbar ist, dass der Differentialzylinder hydraulisch vorgespannt ist. Erfindungsgemäß ist an die Rücklaufleitung ein Vorspannventil angeschlossen ist, über das ein Drosselquerschnitt zum Druckmittelspeicher aufsteuerbar ist und das von dem Druck, der in der Vorlaufleitung ansteht, in Öffnungsrichtung und von einer Vorspannfeder in Schließrichtung beaufschlagt ist. Stellt man nun die Pumpenanordnung so ein, dass der von dieser aus dem sich verkleinernden Zylinderraum abgenommene Druckmittelstrom stets kleiner ist als der aus dem sich verkleinernden Zylinderraum verdrängte Druckmittelvolumenstrom, muss der überschüssige Druckmittelvolumenstromanteil über den Drosselquerschnitt zum Druckmittelspeicher verdrängt werden, wodurch ein Vorspanndruck aufgebaut wird.The hydrostatic transmission according to claim 1 has a differential cylinder with a bottom-side cylinder space to which a flow line is connected, and with a piston rod side cylinder space to which a return line is connected, and a pump assembly. In this case, a first connection and a second connection of the pump arrangement to the supply line and a third connection of the pump arrangement to the return line are connected. Pressure fluid can be conveyed from a decreasing cylinder space of the differential cylinder or from a pressure medium reservoir into a cylinder space that enlarges such that the differential cylinder is hydraulically prestressed. According to the invention, a biasing valve is connected to the return line, via which a throttle cross-section can be opened to the accumulator and which is acted upon by the pressure which is present in the flow line in the opening direction and by a biasing spring in the closing direction. If the pump arrangement is now set so that the pressure medium flow removed therefrom from the decreasing cylinder space is always smaller than the pressure medium volume flow displaced from the decreasing cylinder space, the excess pressure fluid volume flow component must be displaced via the throttle cross section to the pressure medium reservoir, whereby a biasing pressure is built up.

Das hydrostatische Getriebe gemäß Patentanspruch 2 besitzt ebenfalls einen Differentialzylinder mit einem bodenseitigen Zylinderraum, an den eine Vorlaufleitung angeschlossen ist, und mit einem kolbenstangenseitigen Zylinderraum, an den eine Rücklaufleitung angeschlossen ist, und eine Pumpenanordnung. Dabei sind wiederum ein erster Anschluss und ein zweiter Anschluss der Pumpenanordnung mit der Vorlaufleitung und ein dritter Anschluss der Pumpenanordnung mit der Rücklaufleitung verbunden. Druckmittel ist aus einem sich verkleinernden Zylinderraum des Differentialzylinders oder aus einem Druckmittelspeicher in einen sich vergrößernden Zylinderraum derart förderbar ist, dass der Differentialzylinder hydraulisch vorgespannt ist. Erfindungsgemäß ist dem bodenseitigen Zylinderraum des Differentialzylinders ein Vorspannventil zugeordnet ist, über das ein Drosselquerschnitt aufsteuerbar ist, wobei dieses Vorspannventil zwischen einem vierten Anschluss der Pumpenanordnung und dem Druckmittelspeicher angeordnet ist und vom Druck in der Rücklaufleitung in Öffnungsrichtung und von einer Vorspannfeder in Schließrichtung beaufschlagt ist.The hydrostatic transmission according to claim 2 also has a differential cylinder with a bottom-side cylinder space to which a flow line is connected, and with a piston rod-side cylinder space to which a return line is connected, and a pump assembly. In this case, in turn, a first connection and a second connection of the pump arrangement to the supply line and a third connection of the pump arrangement to the return line are connected. Pressure fluid can be conveyed from a decreasing cylinder chamber of the differential cylinder or from a pressure medium reservoir into a cylinder chamber that enlarges such that the differential cylinder is hydraulically preloaded. According to the invention, the base-side cylinder chamber of the differential cylinder is assigned a preload valve via which a throttle cross-section can be opened, this preload valve being arranged between a fourth connection of the pump arrangement and the pressure medium accumulator and acted upon by the pressure in the return line in the opening direction and by a pretensioning spring in the closing direction.

Bei dem hydrostatischen Getriebe gemäß Patentanspruch 2 sind vorteilhafterweise zwischen dem Druckmittelspeicher und dem vierten Anschluss der Pumpenanordnung ein zu dem vierten Anschluss hin öffnendes, erstes Rückschlagventil und zwischen dem vierten Anschluss und der Vorlaufleitung ein zu dieser hin öffnendes, zweites Rückschlagventil angeordnet. Bei einer Vergrößerung des bodenseitigen Zylinderraums wird über das erste Rückschlagventil Druckmittel aus dem Druckspeicher angesaugt und über die Pumpenanordnung zum Zylinderraum gefördert.In the case of the hydrostatic transmission according to claim 2, a first non-return valve opening toward the fourth connection and a second non-return valve opening towards the fourth connection are advantageously arranged between the accumulator and the fourth connection of the pump arrangement. With an enlargement of the bottom-side cylinder chamber, pressure medium is sucked out of the pressure accumulator via the first check valve and conveyed via the pump arrangement to the cylinder chamber.

Bei einer besonders einfach aufgebauten Lösung werden über den ersten Anschluss und den zweiten Anschluss der Pumpenanordnung gleich große Fördervolumina geführt. Dabei ist es für den Erhalt der Vorspannung bevorzugt, wenn das Flächenverhältnis des Differentialzylinders kleiner als 2 gewählt ist.In a particularly simply constructed solution, equal delivery volumes are conducted via the first connection and the second connection of the pump arrangement. It is preferable for obtaining the bias voltage when the area ratio of the differential cylinder is set smaller than 2.

Bei einem hydrostatischen Getriebe mit einem Differentialylinder ist vorzugsweise jedem der Zylinderräume ein Vorspannventil zugeordnet.In a hydrostatic transmission with a differential cylinder, preferably each of the cylinder chambers is assigned a preload valve.

Die Pumpenanordnung ist besonders einfach aufgebaut, wenn diese zwei synchron verstellbare Pumpen hat. Alternativ können auch eine Split-Flow-Verstellpumpe, eine Split-Flow-Konstantpumpe mit variabler Drehzahl und umkehrbarer Förderrichtung, eine sogenannte Floating-Cup-Verstellpumpe mit Synchronverstellung (siehe hierzu DE 10 2006 003 122 ) oder eine Floating-Cup-Konstantpumpe mit variabler Drehzahl und umkehrbarer Förderrichtung oder ähnliche Pumpenkonstruktionen eingesetzt werden.The pump assembly is particularly simple if it has two synchronously adjustable pumps. Alternatively, a split-flow variable displacement pump, a variable-speed split-flow variable displacement pump and a reversible conveying direction, a so-called floating cup variable displacement pump with synchronous adjustment (see DE 10 2006 003 122 ) or a floating cup fixed displacement pump with variable speed and reversible conveying direction or similar pump designs are used.

Der Druckspeicher kann als Tank oder als vorgespannter Niederdruckspeicher ausgeführt sein.The accumulator can be designed as a tank or as a prestressed low-pressure accumulator.

Im Folgenden werden bevorzugte Ausführungsbeispiele der Erfindung anhand schematischer Zeichnungen näher erläutert. Es zeigen:

  • Figur 1 ein Schaubild eines ersten Ausführungsbeispiels eines hydrostatischen Getriebes mit Differentialzylinder und zwei synchron verstellbaren Pumpen und
  • Figur 2 ein Ausführungsbeispiel mit einer Split-Flow-Verstellpumpe.
In the following preferred embodiments of the invention will be explained in more detail with reference to schematic drawings. Show it:
  • FIG. 1 a diagram of a first embodiment of a hydrostatic transmission with differential cylinder and two synchronously adjustable pumps and
  • FIG. 2 an embodiment with a split-flow variable displacement pump.

In Figur 1 ist ein hydrostatisches Getriebe 1 mit einem Primärteil 2 und einem Sekundärteil 4 dargestellt. Letzteres ist durch einen Differentialzylinder 6 gebildet, dessen Differentialkolben 8 die Wirkflächen A1 und A2 hat. Der Differentialkolben 8 unterteilt den Differentialzylinder in einen bodenseitigen Zylinderraum 10 mit der Querschnittsfläche A1 und einen kolbenstangenseitigen Ringraum 12 mit der Ringfläche A2. Das Sekundärteil 4 ist bei dem in Figur 1 dargestellten Ausführungsbeispiel durch zwei synchron verstellbare Verstellpumpen 14, 16 ausgebildet, die von einem gemeinsamen Motor 18 angetrieben werden. Bei dem beschriebenen Ausführungsbeispiel sei angenommen, dass die Verstellpumpen 14, 16 das gleiche Fördervolumen haben. Erfindungsgemäß ist der Differentialkolben 8 dann so ausgelegt, dass das Stirnflächenverhältnis A1 / A2 < 2 ist. Dadurch ist sichergestellt, dass die aus dem Differentialzylinder 6 verdrängte Druckmittelmenge stets größer ist als die den beiden Pumpen 14, 16 zugeführte Durckmittelvolumenmenge ist. Die Überschußmenge wird - wie im Folgenden noch näher erläutert - zu einem Tank 20 hin abgeführt. Der Zylinderraum 10 ist über eine sich verzweigende Druckleitung 22 mit den beiden in Figur 1 oben liegenden Anschlüssen P1 und P2 der beiden Verstellpumpen 14, 16 verbunden. Diese Anschlüsse werden im Folgenden als Druckanschlüsse bezeichnet obwohl sie beim Einfahren des Differentialkolbens 8 als Sauganschlüsse wirken, wobei entsprechend dann auch die Druckleitung 22 eine Saugleitung ist.In FIG. 1 a hydrostatic transmission 1 with a primary part 2 and a secondary part 4 is shown. The latter is formed by a differential cylinder 6, the differential piston 8 has the active surfaces A 1 and A 2 . The differential piston 8 divides the differential cylinder into a bottom-side cylinder chamber 10 with the cross-sectional area A 1 and a piston rod-side annular space 12 with the annular surface A 2 . The secondary part 4 is at the in FIG. 1 illustrated embodiment by two synchronously adjustable variable displacement pumps 14, 16 which are driven by a common motor 18. In the described embodiment, it is assumed that the variable displacement pumps 14, 16 have the same delivery volume. According to the invention, the differential piston 8 is then designed so that the end face ratio A 1 / A 2 <2. This ensures that the amount of pressure medium displaced from the differential cylinder 6 is always greater than the amount of pressure medium supplied to the two pumps 14, 16. The excess amount is - as explained in more detail below - discharged to a tank 20 out. The cylinder chamber 10 is connected via a branching pressure line 22 with the two in FIG. 1 overhead connections P 1 and P 2 of the two variable displacement pumps 14, 16 connected. These connections are hereinafter referred to as pressure ports although they act as retraction ports when retracting the differential piston 8, wherein then also the pressure line 22 is a suction line.

Der Ringraum 12 des Differentialzylinders 6 ist über eine Rücklaufleitung 24 mit einem Sauganschluß S2 der Verstellpumpe 14 verbunden. Ein Sauganschluß S1 der weiteren Verstellpumpe 16 ist über eine Saugleitung 26 und ein in Richtung zum Tank 20 sperrendes Rückschlagventil 28 mit dem Tank 20 verbunden. Bei dem dargestellten Ausführungsbeispiel ist desweiteren die Saugleitung 26 über eine Förderleitung 30 und ein weiteres in Richtung zum Tank 20 sperrendes Rückschlagventil 32 mit der Druckleitung 22 verbunden. Von der Rücklaufleitung 24 zweigt eine Tankleitung 34 ab, in der ein Vorspannventil 36 angeordnet ist, über das ein Drosselquerschnitt zum Tank 20 hin einstellbar ist. Das Vorspannventil 36 hat einen Schieber 38, der in Richtung seiner Schließstellung durch die Kraft einer Vorspannfeder 40 und in Richtung einer Vergrößerung des Öffnungsquerschnitts durch einen Steuerdruck beaufschlagt ist, der über eine Vorspannsteuerleitung 42 von der Druckleitung 22 abgegriffen ist. Sobald der in der Vorspannsteuerleitung 42 und damit in der Druckleitung 22 wirkende Druck so groß ist, dass die in Öffnungsrichtung auf den Schieber 38 wirksame Kraft größer ist als die Kraft der Vorspannfeder 40, wird der Schieber 38 aus seiner dargestellten Schließposition herausbewegt und über eine Steuerkante 44 ein Drosselquerschnitt zum Tank hin aufgesteuert. Dieser Drosselquerschnitt hängt - wie gesagt - vom Druck in der Druckleitung 22 ab und ist somit variabel.The annular space 12 of the differential cylinder 6 is connected via a return line 24 with a suction port S 2 of the variable displacement pump 14. A suction connection S 1 of the further variable displacement pump 16 is connected to the tank 20 via a suction line 26 and a non-return valve 28 which closes in the direction of the tank 20. In the illustrated embodiment, furthermore, the suction line 26 is over a Delivery line 30 and another in the direction of the tank 20 blocking check valve 32 connected to the pressure line 22. From the return line 24 branches off a tank line 34, in which a biasing valve 36 is arranged, via which a throttle cross section to the tank 20 is adjustable. The biasing valve 36 has a slide 38 which is acted upon in the direction of its closed position by the force of a biasing spring 40 and in the direction of increasing the opening cross section by a control pressure, which is tapped via a bias control line 42 from the pressure line 22. As soon as the pressure acting in the biasing control line 42 and therefore in the pressure line 22 is so great that the force acting in the opening direction on the slider 38 is greater than the force of the biasing spring 40, the slider 38 is moved out of its illustrated closing position and over a control edge 44 opened a throttle cross-section to the tank out. This throttle cross-section depends - as I said - from the pressure in the pressure line 22 and is thus variable.

In entsprechender Weise zweigt von der Saugleitung 26 eine weitere Tankleitung 46 ab, in der ein weiteres Vorspannventil 48 angeordnet ist, dessen Aufbau gleich demjenigen des Vorspannventils 36 ist. Dementsprechend hat das weitere Vorspannventil 48 einen Schieber 50 mit einer Steuerkante 52, der durch eine Vorspannfeder 54 in seine dargestellte Schließposition vorgespannt ist und in Richtung einer Vergrößerung des Drosselquerschnitts vom Steuerdruck in einer Steuerleitung 56 beaufschlagt ist, die von der Rücklaufleitung 24 abzweigt. Dementsprechend ist der Drosselquerschnitt des Vorspannventils 48 vom Druck in der Rücklaufleitung 24 bestimmt.In a corresponding manner branches off from the suction line 26, a further tank line 46, in which a further biasing valve 48 is arranged, whose construction is equal to that of the biasing valve 36. Accordingly, the further biasing valve 48 has a slider 50 with a control edge 52 which is biased by a biasing spring 54 in its illustrated closed position and is acted upon in the direction of increasing the throttle cross section of the control pressure in a control line 56 which branches off from the return line 24. Accordingly, the throttle area of the biasing valve 48 is determined by the pressure in the return line 24.

Zum Ausfahren des Differentialzylinders 6 wird der Motor 18 über eine nicht dargestellte Pumpensteuerung derart angesteuert, dass beide Verstellpumpen 14, 16 Druckmittel über die Druckleitung 22 in den Zylinderraum 10 fördern. Dabei wird aus dem Ringraum 12 verdrängtes Druckmittel über die Rücklaufleitung 24 zum Sauganschluß S2 der Verstellpumpe 14 geführt. Die zusätzliche, zum Füllen des Zylinderraums 10 erforderliche Druckmittelmenge wird von der Verstellpumpe 16 über den Sauganschluß S1, die Saugleitung 26, das sich öffnende Rückschlagventil 28 aus dem Tank 20 angesaugt. Zu Beginn der Verfahrbewegung ist das Vorspannventil 36 noch geschlossen und der Druck im Zylinderraum 10 steigt relativ schnell an. Durch diesen ansteigenden Druck in der Druckleitung 22 wird dann gegen die Kraft der Vorspannfeder 40 der Drosselquerschnitt des Vorspannventils 36 aufgesteuert, so dass die überschüssige Druckmittelmenge zum Tank 20 gefördert wird und der Differentialzylinder 6 entsprechend des Drosselquerschnitts vorgespannt ist. Dieser Vorspanndruck nimmt mit zunehmenden Druck in der Druckleitung 22 ab. Während dieser Ausfahrbewegung bleibt das weitere Vorspannventil 48 geschlossen, da der Druck in der Rücklaufleitung 24 nicht ausreicht, um dieses gegen die Kraft der Vorspannfeder 54 zu öffnen. Die Ausfahrgeschwindigkeit wird über das synchrone Schwenken der beiden Verstellpumpen 14, 16 eingestellt.To extend the differential cylinder 6, the motor 18 is controlled via a pump control, not shown, such that both variable displacement pumps 14, 16 convey pressure medium via the pressure line 22 into the cylinder chamber 10. In this case, out of the annular space 12 displaced pressure medium via the return line 24 to the suction port S 2 of the variable displacement pump 14 is performed. The additional, required to fill the cylinder chamber 10 pressure medium quantity is sucked by the variable displacement pump 16 via the suction port S 1 , the suction line 26, the opening check valve 28 from the tank 20. At the beginning of the movement, the biasing valve 36 is still closed and the pressure in the cylinder chamber 10 increases relatively quickly. By this increasing pressure in the pressure line 22, the throttle cross-section of the biasing valve 36 is then turned against the force of the biasing spring 40, so that the excess amount of pressure medium is conveyed to the tank 20 and the differential cylinder 6 is biased according to the throttle cross-section. This bias pressure decreases with increasing pressure in the pressure line 22. While this extension movement, the further biasing valve 48 remains closed because the pressure in the return line 24 is not sufficient to open this against the force of the biasing spring 54. The extension speed is set via the synchronous pivoting of the two variable displacement pumps 14, 16.

Zum Einfahren des Differentialzylinders 6 werden die Verstellpumpen so verschwenkt, dass die Förderrichtung umgekehrt wird, so dass über die Verstellpumpe 14 Druckmittel in den Ringraum 12 gefördert wird. Die beiden "Druckanschlüsse" P1 und P2 der beiden Verstellpumpen 14, 16 wirken dann als Sauganschlüsse, über die das Druckmittel aus dem Zylinderraum 10 den beiden Verstellpumpen 14, 16 zugeführt wird. Die Verstellpumpe 16 fördert dann über den als Druckanschluß wirkenden Anschluß S1 Druckmittel in die Saugleitung 26 und von dort über das sich öffnende weitere Rückschlagventil 32 und die Förderleitung 30 zurück zur Saugleitung 22. Der aufgrund der vorgeschriebenen Flächenverhältnisse vorhandene überschüssige Anteil des Druckmittels wird über die weitere Tankleitung 46 und das sich bei einem Druckaufbau in der Rücklaufleitung 24 öffnende weitere Vorspannventil 48 zum Tank 20 hin abgeführt. Genau wie beim vorbeschriebenen Ausfahren des Differentialzylinders 6 hängt der eingestellte Drosselquerschnitt und damit die Vorspannung des Differentialzylinders 6 vom Druck in der Rücklaufleitung 24 ab, so dass der Drosselquerschnitt mit zunehmenden Druck im Ringraum 12 vergrößert wird und somit die Vorspannung abnimmt.For retracting the differential cylinder 6, the variable displacement pumps are pivoted so that the conveying direction is reversed, so that via the variable displacement 14 pressure medium is conveyed into the annular space 12. The two "pressure ports" P 1 and P 2 of the two variable displacement pumps 14, 16 then act as suction ports, via which the pressure medium from the cylinder chamber 10 the two variable displacement pumps 14, 16 is supplied. The variable displacement pump 16 then promotes via the port acting as a pressure connection S 1 pressure medium in the suction line 26 and from there via the opening another check valve 32 and the delivery line 30 back to the suction line 22. The existing due to the prescribed area ratios excess portion of the pressure medium is on the another tank line 46 and the further biasing valve 48 opening at a pressure build-up in the return line 24 to the tank 20 toward discharged. Just like the above-described extension of the differential cylinder 6, the set throttle cross-section and thus the bias of the differential cylinder 6 depends on the pressure in the return line 24, so that the throttle cross section is increased with increasing pressure in the annular space 12 and thus decreases the bias.

Das Ausführungsbeispiel ist nicht darauf beschränkt, dass beide Pumpen 14, 16 mit dem gleichem Fördervolumen fördern. Prinzipiell ist auch keine synchrone Ansteuerung erforderlich, diese Pumpen 14, 16 könnten auch unabhängig voneinander ansteuerbar sein. Bei ungleichen Fördermengen sollte auch der verdrängte Druckmittelvolumenstrom stets etwas größer als der den Pumpen zugeführte Druckmittelvolumenstrom sein, so dass die Überschußmenge über zumindest ein Vorspannventil zum Tank hin abgeführt werden kann und entsprechend der Einstellung des Drosselquerschnitts eine Vorspannung erfolgt.The exemplary embodiment is not restricted to the fact that both pumps 14, 16 convey with the same delivery volume. In principle, no synchronous control is required, these pumps 14, 16 could also be controlled independently of each other. For unequal flow rates and the displaced pressure medium flow should always be slightly larger than the pressure medium flow supplied to the pump, so that the excess amount can be discharged through at least one biasing valve to the tank and according to the setting of the throttle cross section, a bias occurs.

Anstelle der vorbeschriebenen Verstellpumpen 14, 16 können auch andere Pumpenkonstruktionen eingesetzt werden. Figur 2 zeigt ein entsprechendes Ausführungsbeispiel, bei dem anstelle der beiden von einer gemeinsamen Motorwelle angetriebenen Verstellpumpen 14, 16 eine sogenannte Split-Flow-Verstellpumpe 58 verwendet werden kann. Derartige Split-Flow-Verstellpumpen 58 können beispielsweise in Axialkolbenbauweise ausgeführt sein, wobei die Vielzahl von Axialkolben in zwei gleiche Teile aufgeteilt ist, um zwei getrennte Druckmittelvolumenströme gleicher Größe bereit zu stellen. Bei dem in Figur 2 verwendeten Symbol einer derartigen Pumpe würde dann ein Teil der Axialkolben (je nach Förderrichtung) beispielsweise Druckmittel über die Sauganschlüsse S1 bzw. S2 ansaugen und dann über die beiden getrennten Druckanschlüsse P1 bzw. P2 in die Druckleitung 22 fördern. Im übrigen ist der Aufbau des hydrostatischen Getriebes identisch zu denjenigen aus Figur 1, so dass weitere Erläuterungen entbehrlich sind.Instead of the above-described variable displacement pumps 14, 16, other pump designs can be used. FIG. 2 shows a corresponding embodiment, in which instead of the two driven by a common motor shaft variable displacement pumps 14, 16, a so-called split-flow variable displacement pump 58 can be used. Such split-flow variable displacement pumps 58 may, for example, be designed in axial piston construction, wherein the multiplicity of axial pistons are divided into two equal parts in order to produce two separate pressure medium volume flows To provide size. At the in FIG. 2 used symbol of such a pump would then suck a part of the axial piston (depending on the direction), for example pressure medium through the suction ports S 1 and S 2 and then promote the two separate pressure ports P 1 and P 2 in the pressure line 22. Incidentally, the structure of the hydrostatic transmission is identical to those of FIG. 1 , so that further explanations are dispensable.

Anstelle der in Figur 1 verwendeten Verstellpumpen können selbstverständlich auch ähnlich wie beim Stand der Technik gemäß der DE 103 42 102 A1 zwei von einem gemeinsamen Motor angetriebene Konstantpumpen verwendet werden, wobei dann entsprechend der Motor in seiner Drehrichtung umkehrbar und hinsichtlich seiner Drehzahl verstellbar ausgeführt sein muß. Als besonders gut geeignet haben sich desweiteren noch sogenannte "Floating-Cup- Pumpen" herausgestellt, die auf eine Entwicklung der Anmelderin zurückgehen und die als Verstellpumpe mit Synchronverstellung oder als Konstantpumpe mit variabler und umkehrbarer Drehzahl ausgeführt sein können. Derartige Floating-Cup-Pumpen sind beispielsweise in der DE 10 2006 003 122 der Anmelderin beschrieben.Instead of in FIG. 1 Of course, used variable displacement pumps can also similar to the prior art according to the DE 103 42 102 A1 two constant-displacement pumps driven by a common motor are used, in which case the motor must be reversible in its direction of rotation and adjustable in its rotational speed. Furthermore, so-called "floating-cup pumps" have proven to be particularly suitable, which are based on a development of the Applicant and which can be designed as a variable displacement pump with synchronous adjustment or as a fixed displacement pump with variable and reversible speed. Such floating cup pumps are for example in the DE 10 2006 003 122 the applicant described.

Claims (7)

  1. Hydrostatic transmission having a differential cylinder (6) with a base-side cylinder chamber (10) to which a feed line (22) is connected, and having a piston-rod-side cylinder chamber (12) to which a return line (24) is connected, and having a pump arrangement (2, 58), wherein a first port (P1) and a second port (P2) of the pump arrangement (2, 58) are connected to the feed line (22) and a third port (S2) of the pump arrangement (2, 58) is connected to the return line (24), and wherein pressure medium can be delivered from a cylinder chamber (10, 12), which is decreasing in size, of the differential cylinder or from a pressure medium store (T) into a cylinder chamber (12, 10) which is increasing in size, in such a way that the differential cylinder (6) is hydraulically preloaded, characterized in that there is connected to the return line (24) a preload valve (36) by means of which a throttle cross section to the pressure medium store (T) can be enlarged in a controlled manner and which is acted on in the opening direction by the pressure prevailing in the feed line (22) and is acted on in the closing direction by a preload spring (40).
  2. Hydrostatic transmission having a differential cylinder (6) with a base-side cylinder chamber (10) to which a feed line (22) is connected, and having a piston-rod-side cylinder chamber (12) to which a return line (24) is connected, and having a pump arrangement (2, 58), wherein a first port (P1) and a second port (P2) of the pump arrangement (2, 58) are connected to the feed line (22) and a third port (S2) of the pump arrangement (2, 58) is connected to the return line (24), and wherein pressure medium can be delivered from a cylinder chamber (10, 12), which is decreasing in size, of the differential cylinder or from a pressure medium store (T) into a cylinder chamber (12, 10) which is increasing in size, in such a way that the differential cylinder (6) is hydraulically preloaded, characterized in that the base-side cylinder chamber (10) of the differential cylinder (6) is assigned a preload valve (48) by means of which a throttle cross section can be enlarged in a controlled manner, and in that said preload valve (48) is arranged between a fourth port (S1) of the pump arrangement (2, 58) and the pressure medium store (T) and is acted on in the opening direction by the pressure in the return line (24) and is acted on in the closing direction by a preload spring (54).
  3. Hydrostatic transmission according to Patent Claim 2, wherein a first check valve (28) is arranged between the pressure medium store (T) and the fourth port (S1) of the pump arrangement (2, 58) and opens in the direction of the fourth port, and a second return valve (32) is arranged between the fourth port and the feed line (22) and opens in the direction of said feed line.
  4. Hydrostatic transmission according to Patent Claim 1, 2 or 3, wherein delivery volumes of equal magnitude are conducted via the first port (P1) and the second port (P2) of the pump arrangement.
  5. Hydrostatic transmission according to Patent Claim 4, wherein the drive output motor is a differential cylinder (6) with an area ratio A1/A2 < 2.
  6. Hydrostatic transmission according to one of the preceding patent claims, wherein the pump arrangement has two synchronously adjustable variable displacement pumps (14, 16), or a split flow variable displacement pump or a split flow fixed displacement pump with a variable and reversible rotational speed or a floating cup variable displacement pump or a floating cup fixed displacement pump with a variable, reversible rotational speed.
  7. Hydrostatic transmission according to one of the preceding patent claims, wherein the pressure medium store is a tank (20) or a preloaded low-pressure store.
EP07785900A 2006-09-25 2007-07-05 Hydrostatic gear mechanism Not-in-force EP2069641B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE200610045211 DE102006045211A1 (en) 2006-09-25 2006-09-25 Hydrostatic transmission
PCT/EP2007/005930 WO2008037307A1 (en) 2006-09-25 2007-07-05 Hydrostatic gear mechanism

Publications (2)

Publication Number Publication Date
EP2069641A1 EP2069641A1 (en) 2009-06-17
EP2069641B1 true EP2069641B1 (en) 2012-05-16

Family

ID=38508787

Family Applications (1)

Application Number Title Priority Date Filing Date
EP07785900A Not-in-force EP2069641B1 (en) 2006-09-25 2007-07-05 Hydrostatic gear mechanism

Country Status (3)

Country Link
EP (1) EP2069641B1 (en)
DE (1) DE102006045211A1 (en)
WO (1) WO2008037307A1 (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109115488A (en) * 2018-08-02 2019-01-01 清华大学 Gear fatigue experiment loading system fluid pressure line protective device
CN108953249A (en) * 2018-08-02 2018-12-07 清华大学 Gear fatigue experiment hydraulic loading system

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0032300A1 (en) * 1980-01-14 1981-07-22 Rotork Controls Limited Fluid control system
DE4008792A1 (en) * 1990-03-19 1991-09-26 Rexroth Mannesmann Gmbh DRIVE FOR A HYDRAULIC CYLINDER, IN PARTICULAR DIFFERENTIAL CYLINDER
DE19716081C1 (en) * 1997-04-17 1998-08-13 Hydac Technology Gmbh Hydraulic differential cylinder drive
JP2002021807A (en) * 2000-07-10 2002-01-23 Kobelco Contstruction Machinery Ltd Electric motor-driven fluid pressure driving gear and actuator driving gear

Also Published As

Publication number Publication date
EP2069641A1 (en) 2009-06-17
DE102006045211A1 (en) 2008-04-03
WO2008037307A1 (en) 2008-04-03

Similar Documents

Publication Publication Date Title
DE10021793B4 (en) Device for controlling CVT transmissions
EP2024647A1 (en) Hydrostatic drive having volumetric flow compensation
EP1853824B1 (en) Device and method for supplying lubricating oil
EP1588077B1 (en) Control of a hydrostatic gearbox
DE3307582C2 (en) Valve arrangement for controlling a hydrostatic drive or transmission consisting of a pump and motor
DE102010034610A1 (en) Hydraulic linear drive
DE102009045510A1 (en) Device for varying the stroke volumes of a first hydraulic machine and a second hydraulic machine
DE102004062388B4 (en) Hydrostatic drive with speed limitation
DE2911891A1 (en) DEVICE FOR CONTROLLING A HYDROMOTOR
DE102011100862A1 (en) Double clutch
DE102012001462A1 (en) Internal gear pump comprises control bevel, which is provided in area of sealing segment side facing hollow wheel, and is extended out in peripheral direction of hollow wheel and broadens opening area of control groove
DE102008000679A1 (en) Hydraulic control arrangement for controlling a variable fluid volume flow
EP1984629B1 (en) Hydraulic control arrangement with regeneration and lowering brake valve
EP2069641B1 (en) Hydrostatic gear mechanism
DE102009005768B4 (en) Pressure control of a hydraulic drive unit
EP1387090B1 (en) Hydraulic drive
DE102012202904A1 (en) Pump assembly for producing variable volumetric flow in pressure system of automatic transmission used in motor car, has control unit through which position of control slide is actively changed based on control signal
EP1564414B1 (en) Hydraulic drive
EP2985469A1 (en) Hydrostatic drive and valve device for same
EP2069640B1 (en) Hydrostatic drive unit
EP2337949B1 (en) Arrangement for hydraulic eccentric adjustment to set a predefined displacement for a hydrostatic motor
DE10033739B4 (en) Hydrostatic transmission
EP1809507B1 (en) Hydrostatic drive
DE102010030149A1 (en) Stroke volume varying device for hydraulic machine of continuously variable transmission gear-box of vehicle, has piston space that is connectable with another piston space in region of control valve unit based on operating condition
DE1955886C3 (en) Hydrostatic axial piston transmission

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed

Effective date: 20090427

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IS IT LI LT LU LV MC MT NL PL PT RO SE SI SK TR

AX Request for extension of the european patent

Extension state: AL BA HR MK RS

17Q First examination report despatched

Effective date: 20090910

GRAP Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOSNIGR1

DAX Request for extension of the european patent (deleted)
GRAS Grant fee paid

Free format text: ORIGINAL CODE: EPIDOSNIGR3

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IS IT LI LT LU LV MC MT NL PL PT RO SE SI SK TR

REG Reference to a national code

Ref country code: GB

Ref legal event code: FG4D

Free format text: NOT ENGLISH

REG Reference to a national code

Ref country code: CH

Ref legal event code: EP

REG Reference to a national code

Ref country code: AT

Ref legal event code: REF

Ref document number: 558237

Country of ref document: AT

Kind code of ref document: T

Effective date: 20120615

REG Reference to a national code

Ref country code: IE

Ref legal event code: FG4D

Free format text: LANGUAGE OF EP DOCUMENT: GERMAN

REG Reference to a national code

Ref country code: DE

Ref legal event code: R096

Ref document number: 502007009879

Country of ref document: DE

Effective date: 20120712

REG Reference to a national code

Ref country code: NL

Ref legal event code: VDEP

Effective date: 20120516

REG Reference to a national code

Ref country code: LT

Ref legal event code: MG4D

Effective date: 20120516

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: LT

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20120516

Ref country code: IS

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20120916

Ref country code: PL

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20120516

Ref country code: SE

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20120516

Ref country code: CY

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20120516

Ref country code: FI

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20120516

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GR

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20120817

Ref country code: PT

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20120917

Ref country code: LV

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20120516

Ref country code: SI

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20120516

BERE Be: lapsed

Owner name: ROBERT BOSCH G.M.B.H.

Effective date: 20120731

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: CZ

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20120516

Ref country code: RO

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20120516

Ref country code: NL

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20120516

Ref country code: SK

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20120516

Ref country code: EE

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20120516

Ref country code: DK

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20120516

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: MC

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20120731

Ref country code: IT

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20120516

REG Reference to a national code

Ref country code: CH

Ref legal event code: PL

PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed

Effective date: 20130219

GBPC Gb: european patent ceased through non-payment of renewal fee

Effective date: 20120816

REG Reference to a national code

Ref country code: FR

Ref legal event code: ST

Effective date: 20130329

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: ES

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20120827

Ref country code: LI

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20120731

Ref country code: FR

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20120731

Ref country code: CH

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20120731

REG Reference to a national code

Ref country code: IE

Ref legal event code: MM4A

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: BE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20120731

REG Reference to a national code

Ref country code: DE

Ref legal event code: R097

Ref document number: 502007009879

Country of ref document: DE

Effective date: 20130219

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GB

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20120816

Ref country code: MT

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20120516

Ref country code: BG

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20120816

Ref country code: IE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20120705

REG Reference to a national code

Ref country code: AT

Ref legal event code: MM01

Ref document number: 558237

Country of ref document: AT

Kind code of ref document: T

Effective date: 20120731

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: AT

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20120731

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: TR

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20120516

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: LU

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20120705

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: HU

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20070705

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DE

Payment date: 20190924

Year of fee payment: 13

REG Reference to a national code

Ref country code: DE

Ref legal event code: R119

Ref document number: 502007009879

Country of ref document: DE

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20210202