EP2251549B1 - Hydraulic assembly - Google Patents

Hydraulic assembly Download PDF

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Publication number
EP2251549B1
EP2251549B1 EP20100004301 EP10004301A EP2251549B1 EP 2251549 B1 EP2251549 B1 EP 2251549B1 EP 20100004301 EP20100004301 EP 20100004301 EP 10004301 A EP10004301 A EP 10004301A EP 2251549 B1 EP2251549 B1 EP 2251549B1
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EP
European Patent Office
Prior art keywords
pressurising medium
accumulator
hydraulic system
valve
pressure
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.)
Active
Application number
EP20100004301
Other languages
German (de)
French (fr)
Other versions
EP2251549A3 (en
EP2251549A2 (en
Inventor
Marcus Karl Pfeiffer
Frank Dr. Bauer
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.)
Hydac Filtertechnik GmbH
Original Assignee
Hydac Filtertechnik GmbH
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Publication date
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Publication of EP2251549A2 publication Critical patent/EP2251549A2/en
Publication of EP2251549A3 publication Critical patent/EP2251549A3/en
Application granted granted Critical
Publication of EP2251549B1 publication Critical patent/EP2251549B1/en
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Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B11/00Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/16Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors
    • F15B11/161Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors with sensing of servomotor demand or load
    • F15B11/162Servomotor 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
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B66HOISTING; LIFTING; HAULING
    • B66FHOISTING, LIFTING, HAULING OR PUSHING, NOT OTHERWISE PROVIDED FOR, e.g. DEVICES WHICH APPLY A LIFTING OR PUSHING FORCE DIRECTLY TO THE SURFACE OF A LOAD
    • B66F9/00Devices for lifting or lowering bulky or heavy goods for loading or unloading purposes
    • B66F9/06Devices for lifting or lowering bulky or heavy goods for loading or unloading purposes movable, with their loads, on wheels or the like, e.g. fork-lift trucks
    • B66F9/075Constructional features or details
    • B66F9/07572Propulsion arrangements
    • EFIXED CONSTRUCTIONS
    • E02HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02FDREDGING; SOIL-SHIFTING
    • E02F9/00Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20Drives; Control devices
    • E02F9/22Hydraulic or pneumatic drives
    • E02F9/2217Hydraulic or pneumatic drives with energy recovery arrangements, e.g. using accumulators, flywheels
    • EFIXED CONSTRUCTIONS
    • E02HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02FDREDGING; SOIL-SHIFTING
    • E02F9/00Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20Drives; Control devices
    • E02F9/22Hydraulic or pneumatic drives
    • E02F9/2221Control of flow rate; Load sensing arrangements
    • E02F9/2225Control of flow rate; Load sensing arrangements using pressure-compensating valves
    • EFIXED CONSTRUCTIONS
    • E02HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02FDREDGING; SOIL-SHIFTING
    • E02F9/00Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20Drives; Control devices
    • E02F9/22Hydraulic or pneumatic drives
    • E02F9/2278Hydraulic circuits
    • E02F9/2296Systems with a variable displacement pump
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B1/00Installations or systems with accumulators; Supply reservoir or sump assemblies
    • F15B1/02Installations or systems with accumulators
    • F15B1/024Installations or systems with accumulators used as a supplementary power source, e.g. to store energy in idle periods to balance pump load
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B21/00Common features of fluid actuator systems; Fluid-pressure actuator systems or details thereof, not covered by any other group of this subclass
    • F15B21/14Energy-recuperation means
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/20Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/205Systems with pumps
    • F15B2211/20507Type of prime mover
    • F15B2211/20523Internal combustion engine
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/20Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/205Systems with pumps
    • F15B2211/2053Type of pump
    • F15B2211/20546Type of pump variable capacity
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/20Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/205Systems with pumps
    • F15B2211/2053Type of pump
    • F15B2211/20561Type of pump reversible
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/20Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/205Systems with pumps
    • F15B2211/2053Type of pump
    • F15B2211/20569Type of pump capable of working as pump and motor
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/20Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/21Systems with pressure sources other than pumps, e.g. with a pyrotechnical charge
    • F15B2211/212Systems with pressure sources other than pumps, e.g. with a pyrotechnical charge the pressure sources being accumulators
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/30Directional control
    • F15B2211/305Directional control characterised by the type of valves
    • F15B2211/30505Non-return valves, i.e. check valves
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/40Flow control
    • F15B2211/405Flow control characterised by the type of flow control means or valve
    • F15B2211/40523Flow control characterised by the type of flow control means or valve with flow dividers
    • F15B2211/4053Flow control characterised by the type of flow control means or valve with flow dividers using valves
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/40Flow control
    • F15B2211/415Flow control characterised by the connections of the flow control means in the circuit
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/60Circuit components or control therefor
    • F15B2211/63Electronic controllers
    • F15B2211/6303Electronic controllers using input signals
    • F15B2211/6306Electronic controllers using input signals representing a pressure
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/60Circuit components or control therefor
    • F15B2211/63Electronic controllers
    • F15B2211/6303Electronic controllers using input signals
    • F15B2211/6306Electronic controllers using input signals representing a pressure
    • F15B2211/6309Electronic controllers using input signals representing a pressure the pressure being a pressure source supply pressure
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/60Circuit components or control therefor
    • F15B2211/63Electronic controllers
    • F15B2211/6303Electronic controllers using input signals
    • F15B2211/6306Electronic controllers using input signals representing a pressure
    • F15B2211/6313Electronic controllers using input signals representing a pressure the pressure being a load pressure
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/70Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/71Multiple output members, e.g. multiple hydraulic motors or cylinders
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/70Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/78Control of multiple output members
    • F15B2211/781Control of multiple output members one or more output members having priority
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/80Other types of control related to particular problems or conditions
    • F15B2211/88Control measures for saving energy

Definitions

  • the invention relates to a hydraulic system, in particular for a commercial vehicle, such as a construction machine, agricultural machine, forklift, with a pressure medium pump driven by an engine unit, in particular in the form of an internal combustion engine, according to the features in the preamble of claim 1.
  • Hydraulic systems for commercial vehicles are generally composed of several hydrostatic drive systems.
  • these include the cooling, control and feeding hydraulics as well as the driving hydraulics.
  • these systems can work partially independently of each other and fulfill their function.
  • the steering system is regularly operated with a steering valve with "open center", wherein a constant pump often formed as external gear pump promotes non-actuated steering system against the pressure fluid tank of the construction machine.
  • a so-called. Open hydraulic circuit for example, the functions cooling, control and supply circuit can be covered with only one pressure medium pump.
  • This may be an external gear pump with a constant displacement volume, which is connected to a power take-off of the internal combustion engine is mounted as a motor unit.
  • a cooling motor formed, for example, as external gear constant motor a parallel connection of control and feed hydraulic circuit may be provided.
  • the control pressure system is used for signal transmission of certain machine characteristics, such as the control of a disk parking brake or a swivel angle adjustment of the drive pump by means of trigger valve.
  • certain machine characteristics such as the control of a disk parking brake or a swivel angle adjustment of the drive pump by means of trigger valve.
  • WO 2009/083220 A1 goes a regenerative hydrostatic drive system, in particular for a commercial vehicle, such as a construction machine, with a powered by an engine unit, in particular in the form of an internal combustion engine, pressure medium pump, which supplies a first consumer with pressure medium, wherein from the pressure medium pump, a pressure medium storage is rechargeable, wherein at least a priority valve in response to a current power output of the motor unit controls the charging of the accumulator and the pressure medium supply of the consumer, wherein switching on or off of the pressure medium supply of the accumulator to the consumer and another second consumer is controlled by a further valve, and wherein in the fluid flow direction seen from the pressure medium pump, the storage charge via a memory charging circuit after the priority valve is done.
  • EP 0 044 065 A2 goes out a load-detecting hydraulic system.
  • a fluid stream may be temporarily stored from a pump into a hydropneumatic accumulator prior to being used to power a consumer.
  • the invention is therefore based on the object to provide a hydraulic system for a commercial vehicle, which allows a reduction in power (downsizing) for the internal combustion engine.
  • This object is achieved with a hydraulic system with the features in the entirety of claim 1.
  • the pressure fluid accumulator By virtue of the fact that power peaks of the engine unit, in particular in the form of an internal combustion engine, can be compensated for by the use of a pressure fluid accumulator, the pressure fluid accumulator being charged or discharged as a function of a momentary power output of the engine unit, a constructive measure is provided, the overall power of the engine unit in the sense of Downsizing to a predetermined value, for example, the statutory engine power class up to 56 kW limit.
  • the pressure medium supply to the consumers and to the accumulator of the hydraulic system is controlled by a priority valve.
  • a connection and disconnection of the pressure medium supply to one or more consumers is controlled by a further valve.
  • the energy supply of the internal combustion engine is so exploited with the help of a suitable storage charging and discharging that needs to be promoted at a Zuschaltphase the accumulator to a consumer in the ideal case of the pressure medium pump less to no pressure medium to the respective consumer and vice versa, when one or more consumers are out of service, the pressure fluid accumulator is charged in a kind of stationary engine phase of the internal combustion engine.
  • a short-term requirement requirement of a consumer can be covered by the accumulator independently of a current machine cycle.
  • a preferably so-called open basic position of the further valve for connection or disconnection of the consumer based on the accumulator guarantees that, for example, suitable construction or machinery with disconnected internal combustion engine and full accumulator Notlenkeigenschaften a steering system of the construction or working machine can be ensured.
  • the implementation of a parallel hybrid according to the invention in the outlined frame can be based on a resistance or displacement control, wherein the adaptation of the hydraulic pressure fluid storage variables - volume flow and pressure - by the interpretation of the Pressure fluid accumulator discharging valve as a proportional valve is preferred.
  • the throttle losses incurred at the valve can be used to control the system variables.
  • the control of the priority valve is carried out in a particularly preferred embodiment by the use of pressure sensors, whereby the charge and discharge phase of the accumulator and a delivery volume adjustment of a pressure medium source formed as a variable pressure medium pump for the consumer and the accumulator.
  • a first pressure sensor provides a signal reflecting the load pressure of the consumer
  • a second pressure sensor maps a current accumulator pressure of the accumulator
  • a third pressure sensor depicts the fluid pressure on the high pressure side of the pressure medium pump.
  • the priority valve is designed as a 3/2 continuous valve whose functionality is similar to a 3-way flow control unit which preferably experiences a double-sided hydraulic actuation, for example by a pressure sensor which maps the pressure medium storage charge state and detects the fluid pressure on the high pressure side of the pressure medium pump.
  • the accumulator can be configured in a conventional manner as a piston, bubble or diaphragm accumulator. If 2/2-way valves are used as conventional priority valves, they can be expanded by cascading to switch positions obvious. Instead of the aforementioned 3-way flow control unit can also occur another multi-way flow control unit. Overall, however, it should be noted that the priority valve is designed as a continuous valve whose functionality is similar to a multi-way flow control unit.
  • the accumulator has a minimum operating pressure of about 60 bar and a maximum operating pressure of about 350 bar.
  • its storage volume is a total of 20 I.
  • the solution according to the invention is further characterized in that the storage charge takes place in the fluid direction via a storage charging circuit after the priority valve and a feed via a feed valve as a further valve before the priority valve.
  • the consumers may be a cooling fan and / or a control drive and / or a hydraulic power steering and / or a working hydraulics, etc., depending on the machine operating phase, a repeated, short-term shutdown of the consumer or a time shift of the Zuschaltvorganges the consumer in relation to a driving hydraulics of the working machine is conceivable.
  • the 3-way flow control valve as a priority valve provides depending on its switching or sliding position for a hydraulic power supply of the parallel-connected consumers, such as accumulator and hydraulic power steering or power steering. Depending on the hydraulic energy to be retrieved it may be expedient to provide more than one accumulator in the hydraulic system.
  • Fig. 1 is shown in a schematic diagram partially a hydraulic system 1 for a construction machine.
  • the hydraulic system 1 is driven by a designed as a motor unit internal combustion engine 2 (VKM), for example in the form of a diesel engine, with a predetermined effective drive power, for example, with a drive power of 56 kW, for a non-illustrated drive 12 of the construction machine, an energy converter ( Pressure medium pump, transmission, electric motor) is driven, and further an adjustable pressure medium pump 13 is driven and further usable as a pump motor unit pressure medium pump 3, with which the individual consumers of the hydraulic system 1 are supplied with pressure medium 5.
  • VKM motor unit internal combustion engine 2
  • VKM motor unit internal combustion engine 2
  • a predetermined effective drive power for example, with a drive power of 56 kW
  • an energy converter Pressure medium pump, transmission, electric motor
  • an adjustable pressure medium pump 13 is driven and further usable as a pump motor unit pressure medium pump 3, with which the individual consumers of the hydraulic system 1 are supplied with pressure medium 5.
  • Said commercial vehicle has in the embodiments shown in all figures, several hydraulic, especially hydrostatic drive systems in the form of a steering hydraulic 4, a control and feeding 8, possibly even with the inclusion of a cooling hydraulics, and a drive hydraulics 12, which is not shown in detail and the adjustable Pressure medium pump 13, as stated, is supplied.
  • these systems can, in some cases, function independently of each other.
  • a priority valve 7 as a continuous valve, preferably designed as a 3/2 continuous valve, interposed between the first load 4 as part of the steering hydraulic and the pressure medium pump 3.
  • Another second consumer 8 as part of the control and supply hydraulics is connected in parallel to the first consumer 4 to the output side of the priority valve 7.
  • a pressure fluid reservoir 6 is connected in the same way in parallel arrangement on the output side with the priority valve 7, ie in the same way as the consumer 4 and the second consumer 8.
  • the pressure fluid reservoir 6 is required to cover short-term, dynamic power peaks to below the desired in the internal combustion engine 2 to stay within the stipulated performance limit.
  • the multi-way flow control valve particularly preferably constructed as a 3/2-way flow control valve priority valve 7 provides in dependence on its slide position for a hydraulic power supply of the parallel-connected loads 4 and 8 and the accumulator 6.
  • valve 9 For the realization of the discharge phase of the accumulator 6 another valve 9 is used.
  • the other valve 9 can, as the Fig. 6 shows, at the same time receive an automatic, hydraulic pressure signal from the priority valve 7, depending on the load on the consumer.
  • this structure it is possible, for example, to cover short-term requirements of the valve unit by the pressure medium reservoir 6 independently of the machine requirement cycle. In the same way, an energy-saving operation of other consumers, which are controllable with the priority valve 7, be maintained.
  • the steering 4 is opposite the accumulator 6 and the other consumer 8 prioritized, that is, a charge of the accumulator 6 or the other non-safety-relevant consumer 8 only takes place when no steering control is made or the need for the steering operation needs over the priority valve 7 is ensured in each case.
  • a control and / or regulating device 11 perform the charging and discharging phase of the pressure medium reservoir 6.
  • Fig. 3 again shows an operating phase of the hydraulic system 1, in which the accumulator 6 is charged.
  • the various consumers are 4.8 in operation and are supplied with pressure medium 5 in the required extent.
  • the control device 11 has the priority valve 7 to control its operation.
  • the responsible for the pressure medium supply of the hydraulic system 1 pressure medium pump 3 is designed as a pump motor unit, so that at a corresponding pivoting, for example, a cam ring in the pressure medium pump 3, together with the rotatably arranged therein displacement chambers pump chambers (not shown) defined during the discharge process of the accumulator 6 mechanical energy can be obtained in order to realize such a parallel hybrid solution.
  • Fig. 5 shows that relevant check valves 14 may be provided in the supply and feed line from or to the accumulator 6, wherein the check valve 14 between the pressure medium pump 3 and hydraulic accumulator takes over the function of the other valve 9. Furthermore, the valve 9 for discharging the accumulator 6, a pressure compensator function 10 (see. Fig. 6 ), a current control function (cf. Fig. 7 ) or a pressure reducing function (cf. Fig. 8 ).
  • the consumer 4,8 mentioned in the exemplary embodiments can understandably be of a different nature, for example the first consumer 4 does not need to concern the steering hydraulics. Furthermore, both consumers 4.8 could both affect a steering circuit. Thus, the second consumer 8 could be designed as a hydraulic power steering system and the consumer 4 form a conventional auxiliary steering hydraulics. All solutions common and of particular importance, however, is that the storage charge takes place via a storage charging circuit after the priority valve 7 and the feed via the feed valve 9 before the priority valve 7 in the respective fluid direction.
  • Fig. 9 a hydraulic circuit diagram solution is shown in which during the discharge of the accumulator 6, a low pressure side of the pressure medium pump 3 is acted upon by pressure medium 5.
  • the pertinent Fig. 9 and the generalized solution according to the Fig. 10 may also generally have an energy converter, such as a pressure medium pump, a transmission, an electric motor and the like instead of a traction drive 12.

Description

Die Erfindung betrifft eine hydraulische Anlage, insbesondere für ein Nutzfahrzeug, wie eine Baumaschine, Landmaschine, Stapler, mit einer von einer Motoreinheit, insbesondere in Form einer Verbrennungskraftmaschine, angetriebenen Druckmittelpumpe gemäß den Merkmalen im Oberbegriff von Anspruch 1.The invention relates to a hydraulic system, in particular for a commercial vehicle, such as a construction machine, agricultural machine, forklift, with a pressure medium pump driven by an engine unit, in particular in the form of an internal combustion engine, according to the features in the preamble of claim 1.

Hydraulische Anlagen für Nutzfahrzeuge, insbesondere für Baumaschinen, Landmaschinen und Off-Road Arbeitsmaschinen einschließlich Staplern, setzen sich im allgemeinen aus mehreren hydrostatischen Antriebssystemen zusammen. Dazu zählen neben der Lenkhydraulik die Kühl-, Steuer- und Speisehydraulik sowie die Fahrhydraulik. Diese Systeme können in Abhängigkeit von ihrer Grundstruktur teilweise unabhängig voneinander arbeiten und ihrer Funktion nachkommen.Hydraulic systems for commercial vehicles, in particular for construction machines, agricultural machines and off-road machines including forklifts, are generally composed of several hydrostatic drive systems. In addition to the steering hydraulics, these include the cooling, control and feeding hydraulics as well as the driving hydraulics. Depending on their basic structure, these systems can work partially independently of each other and fulfill their function.

Bei fahrenden Baumaschinen ist das Lenksystem regelmäßig mit einem Lenkventil mit "offener Mitte" betrieben, wobei eine häufig als Außenzahnradpumpe gebildete Konstantpumpe bei nicht betätigtem Lenksystem gegen den Druckmitteltank der Baumaschine fördert. Durch den Einsatz eines sog. offenen Hydraulikkreislaufs können beispielsweise die Funktionen Kühl-, Steuer- und Speisekreislauf mit nur einer Druckmittelpumpe abgedeckt werden. Dabei kann es sich um eine Außenzahnradpumpe mit einem konstanten Verdrängervolumen handeln, die an einen Nebenabtrieb der Verbrennungskraftmaschine als Motoreinheit angebracht ist. Nach einem beispielsweise als Außenzahnrad-Konstantmotor gebildeten Kühlmotor kann eine Parallelverschaltung von Steuer- und Einspeisehydraulikkreislauf vorgesehen sein. Das Steuerdrucksystem dient zur Signalübertragung von bestimmten Maschineneigenschaften, wie der Ansteuerung einer Lamellen-Feststellbremse oder einer Schwenkwinkel-Verstelleinrichtung der Fahrpumpe mittels Fahrgeberventil. Durch den Einsatz des Speisesystems erfolgt sowohl die Einspeisung von frischem, gereinigtem Hydrauliköl als auch ein interner Leckageausgleich.In moving construction machines, the steering system is regularly operated with a steering valve with "open center", wherein a constant pump often formed as external gear pump promotes non-actuated steering system against the pressure fluid tank of the construction machine. Through the use of a so-called. Open hydraulic circuit, for example, the functions cooling, control and supply circuit can be covered with only one pressure medium pump. This may be an external gear pump with a constant displacement volume, which is connected to a power take-off of the internal combustion engine is mounted as a motor unit. After a cooling motor formed, for example, as external gear constant motor, a parallel connection of control and feed hydraulic circuit may be provided. The control pressure system is used for signal transmission of certain machine characteristics, such as the control of a disk parking brake or a swivel angle adjustment of the drive pump by means of trigger valve. Through the use of the feed system, both the supply of fresh, purified hydraulic oil and an internal leakage compensation takes place.

Auch die Auslegung mobiler Arbeitsmaschinen ist in den letzten Jahren zusehends durch die Anforderungen der europäischen Abgasgesetzgebung geprägt. So gilt seit 2008 für alle Motorleistungsklassen mobiler Arbeitsmaschinen die europäische Emissionsrichtlinie III A. Nach Inkrafttreten der bereits beschlossenen Abgasstufe III B gilt ab 2010 eine weitere Verringerung der Stickoxyde um bis zu 94%, was nach heutiger Auffassung nur durch den Einsatz von Partikelfiltern umsetzbar ist. Eine letzte Abgasstufennorm IV 2014 sieht eine weitere Senkung der Stickoxyde um bis zu 88% gegenüber der Stufe III B vor. Insbesondere diese letzte Abgasstufe IV stellt die Baumaschinen- und Dieselmotorenhersteller vor große Herausforderungen. Für die Installation eines Selektiven-Katalysator-Systems (SCR) nebst dem dazugehörigen Harnstofftank wird zusätzlicher Einbauraum an der jeweiligen Maschine benötigt, was insbesondere bei Groß-Maschinenserien zu einem hohen konstruktiven und logistischen Aufwand führt.The design of mobile work machines has also become increasingly marked in recent years by the requirements of European emissions legislation. Since 2008, the European Emission Directive III A applies to all engine power classes of mobile machinery. After the entry into force of the already agreed exhaust emission level III B from 2010, a further reduction of nitrogen oxides by up to 94%, which is currently feasible only through the use of particulate filters. A final emissions standard IV 2014 provides for a further reduction of nitrogen oxides by up to 88% compared to Stage III B. In particular, this last emission stage IV presents the construction machinery and diesel engine manufacturers with major challenges. For installation of a selective catalyst system (SCR) together with the associated urea tank, additional installation space is required on the respective machine, which leads to a high constructive and logistical effort, especially in large-scale machine series.

Unter Berücksichtigung der aufwendigen Abgasnachbehandlungssysteme und die damit verbundenen Auswirkungen stellt insbesondere die Motorleistungsklasse bis 56 kW durch das Wegfallen der EU-Abgasnorm IV eine interessante Alternative für Maschinenhersteller dar. Mittels einer energetischen Optimierung der bestehenden Antriebssysteme ist eine dieselmotorische Leistungsreduzierung bis unterhalb der genannten 56 kW-Leistungsgrenze erzielbar, d.h. es wird das sog. "Downsizing" der Verbrennungskraftmaschine angestrebt.Taking into account the elaborate exhaust aftertreatment systems and the associated effects, especially the engine performance class up to 56 kW by eliminating the EU emission standard IV is an interesting alternative for machine manufacturers. By means of an energetic optimization of the existing drive systems, a diesel engine power reduction to below the mentioned 56 kW power limit achievable, ie it is the so-called "downsizing" of the internal combustion engine sought.

Aus der WO 2009/083220 A1 geht ein regeneratives hydrostatisches Antriebssystem, insbesondere für ein Nutzfahrzeug, wie eine Baumaschine, hervor mit einer von einer Motoreinheit, insbesondere in Form einer Verbrennungskraftmaschine, angetriebenen Druckmittelpumpe, die einen ersten Verbraucher mit Druckmittel versorgt, wobei von der Druckmittelpumpe ein Druckmittelspeicher aufladbar ist, wobei mindestens ein Prioritätsventil in Abhängigkeit von einer momentanen Leistungsabgabe der Motoreinheit die Aufladung des Druckmittelspeichers und die Druckmittelversorgung des Verbrauchers steuert, wobei ein Zu- oder Abschalten der Druckmittelzufuhr des Druckmittelspeichers zu dem Verbraucher und einem weiteren zweiten Verbraucher von einem weiteren Ventil gesteuert ist, und wobei in Fluidströmungsrichtung von der Druckmittelpumpe aus gesehen die Speicherladung über eine Speicherladeschaltung nach dem Prioritätsventil erfolgt.
Aus der EP 0 044 065 A2 geht ein lastdetektierendes hydraulisches System hervor. Ein Fluidstrom kann ausgehend von einer Pumpe in einen Hydropneumatischen Speicher zwischengespeichert werden, ehe er zum Antreiben eines Verbrauchers genutzt wird.
From the WO 2009/083220 A1 goes a regenerative hydrostatic drive system, in particular for a commercial vehicle, such as a construction machine, with a powered by an engine unit, in particular in the form of an internal combustion engine, pressure medium pump, which supplies a first consumer with pressure medium, wherein from the pressure medium pump, a pressure medium storage is rechargeable, wherein at least a priority valve in response to a current power output of the motor unit controls the charging of the accumulator and the pressure medium supply of the consumer, wherein switching on or off of the pressure medium supply of the accumulator to the consumer and another second consumer is controlled by a further valve, and wherein in the fluid flow direction seen from the pressure medium pump, the storage charge via a memory charging circuit after the priority valve is done.
From the EP 0 044 065 A2 goes out a load-detecting hydraulic system. A fluid stream may be temporarily stored from a pump into a hydropneumatic accumulator prior to being used to power a consumer.

Ausgehend von dem genannten Stand der Technik liegt daher der Erfindung die Aufgabe zugrunde, eine hydraulische Anlage für ein Nutzfahrzeug zu schaffen, die eine Leistungsminderung (Downsizing) für die Verbrennungskraftmaschine erlaubt. Diese Aufgabe wird mit einer hydraulischen Anlage mit den Merkmalen in der Gesamtheit des Patentanspruches 1 gelöst.Based on the cited prior art, the invention is therefore based on the object to provide a hydraulic system for a commercial vehicle, which allows a reduction in power (downsizing) for the internal combustion engine. This object is achieved with a hydraulic system with the features in the entirety of claim 1.

Erfindungsgemäß ist vorgesehen, dass in Fluidströmungsrichtung von der Druckmittelpumpe aus gesehen die Speicherladung über eine Speicherladeschaltung nach dem Prioritätsventil und die Einspeisung über ein Einspeiseventil als weiteres Ventil vor dem Prioritätsventil erfolgt.According to the invention it is provided that in the fluid flow direction from the pressure medium pump from the storage charge via a storage charging circuit after the priority valve and the feed via a feed valve as another valve before the priority valve.

Dadurch, dass Leistungsspitzen der Motoreinheit, insbesondere in Form einer Verbrennungskraftmaschine, durch den Einsatz eines Druckmittelspeichers kompensierbar sind, wobei der Druckmittelspeicher in Abhängigkeit von einer momentanen Leistungsabgabe der Motoreinheit aufgeladen oder entladen wird, ist eine konstruktive Maßnahme geschaffen, die Gesamtleistung der Motoreinheit im Sinne von Downsizing auf einen vorgebbaren Wert, beispielsweise auf die gesetzlich vorgegebene Motorleistungsklasse bis 56 kW, zu begrenzen. Erfindungsgemäß ist dabei die Druckmittelzufuhr zu den Verbrauchern und zu dem Druckmittelspeicher der hydraulischen Anlage durch ein Prioritätsventil gesteuert. Ein Zu- und Abschalten der Druckmittelzufuhr zu einem oder mehreren Verbrauchern wird durch ein weiteres Ventil gesteuert.By virtue of the fact that power peaks of the engine unit, in particular in the form of an internal combustion engine, can be compensated for by the use of a pressure fluid accumulator, the pressure fluid accumulator being charged or discharged as a function of a momentary power output of the engine unit, a constructive measure is provided, the overall power of the engine unit in the sense of Downsizing to a predetermined value, for example, the statutory engine power class up to 56 kW limit. According to the invention, the pressure medium supply to the consumers and to the accumulator of the hydraulic system is controlled by a priority valve. A connection and disconnection of the pressure medium supply to one or more consumers is controlled by a further valve.

Bevorzugte Ausführungsformen ergeben sich aus den Unteransprüchen.Preferred embodiments will be apparent from the dependent claims.

Bei einer bevorzugten Ausführungsform der erfindungsgemäßen hydraulischen Anlage wird mit Hilfe einer geeigneten Speicherauflade- und Entladestrategie die Energiebereitstellung der Verbrennungskraftmaschine so ausgenutzt, dass bei einer Zuschaltphase des Druckmittelspeichers zu einem Verbraucher im Idealfall von der Druckmittelpumpe weniger bis kein Druckmittel an den betreffenden Verbraucher gefördert zu werden braucht und umgekehrt, wenn ein oder mehrere Verbraucher außer Betrieb sind, in einer Art stationären Maschinenphase der Verbrennungskraftmaschine der Druckmittelspeicher aufgeladen wird. Durch diesen Systemaufbau kann grundsätzlich durch den Druckmittelspeicher eine kurzzeitige Bedarfsanforderung eines Verbrauchers unabhängig von einem momentanen Maschinenzyklus abgedeckt werden.In a preferred embodiment of the hydraulic system according to the invention the energy supply of the internal combustion engine is so exploited with the help of a suitable storage charging and discharging that needs to be promoted at a Zuschaltphase the accumulator to a consumer in the ideal case of the pressure medium pump less to no pressure medium to the respective consumer and vice versa, when one or more consumers are out of service, the pressure fluid accumulator is charged in a kind of stationary engine phase of the internal combustion engine. As a result of this system structure, a short-term requirement requirement of a consumer can be covered by the accumulator independently of a current machine cycle.

Eine vorzugsweise sog. offene Grundstellung des weiteren Ventils zur Zu- oder Abschaltung des oder der Verbraucher bezogen auf den Druckmittelspeicher garantiert, dass beispielsweise bei dafür geeigneten Bau- oder Arbeitsmaschinen bei abgeschalteter Verbrennungskraftmaschine und vollem Druckmittelspeicher Notlenkeigenschaften eines Lenksystems der Bau- oder Arbeitsmaschine sichergestellt werden.A preferably so-called open basic position of the further valve for connection or disconnection of the consumer based on the accumulator guarantees that, for example, suitable construction or machinery with disconnected internal combustion engine and full accumulator Notlenkeigenschaften a steering system of the construction or working machine can be ensured.

Allgemein besteht bei dem erfindungsgemäßen Hybridisierungskonzept von Verbrauchern die Möglichkeit einer hydraulischen Energieaufnahme- und Rückspeisung sowohl von der Hochdruckseite aus als auch auf der Niederdruckseite der Druckmittelpumpe. Das Ziel der Energiezuführung auf der Pumpenhochdruckseite spiegelt sich hauptsächlich in einer Verbraucherunterstützung wider. Dabei kann eine höhere, kurzzeitige Anfahrdynamik eines Verbrauchers erzielt werden oder eine teilweise Entlastung einer als Verstellpumpe ausgebildeten Druckmittelpumpe. Bei einer Entladung des Druckmittelspeichers auf eine Niederdruckseite der Druckmittelpumpe wird eine kurzzeitige Verringerung des Antriebsmomentes der Druckmittelpumpe erreicht. Dies stellt auch eine Möglichkeit einer wesentlich effizienteren Energieausnutzung dar. Wie dargelegt ist also nicht nur eine Einspeisung auf der Hochdruckseite der Pumpen-Motoreinheit möglich, sondern gleich wohl auch eine Einspeisung auf der Niederdruckseite. Für eine Einspeisung an der Saugseite der Pumpe ist bevorzugt ein zusätzliches Rückschlagventil vorzusehen, das in Richtung der Pumpe öffnet, sowie ein Tankanschluß nach der Pumpe notwendig. Der dahingehende Tankanschluß wird bevorzugt durch einen entsprechenden Anschluß im Prioventil realisiert.In general, in the hybridization concept of consumers according to the invention, there is the possibility of a hydraulic energy absorption and recovery both from the high pressure side and on the low pressure side of the pressure medium pump. The goal of supplying energy to the pump high-pressure side is mainly reflected in consumer support. In this case, a higher, short-term start-up dynamics of a consumer can be achieved or a partial discharge of a pressure medium pump designed as a variable displacement pump. In a discharge of the accumulator to a low pressure side of the pressure medium pump, a short-term reduction of the drive torque of the pressure medium pump is achieved. This also represents a possibility of a much more efficient use of energy. As stated above, not only is it possible to feed in on the high-pressure side of the pump-motor unit, but also to supply it on the low-pressure side. For an injection on the suction side of the pump is preferably an additional check valve to provide, which opens in the direction of the pump, and a tank connection to the pump necessary. The pertinent tank connection is preferably realized by a corresponding connection in Prioventil.

Allgemein kann die Umsetzung eines erfindungsgemäßen Parallelhybrids im skizzierten Rahmen auf Basis einer Widerstands- oder Verdrängersteuerung erfolgen, wobei die Anpassung der hydraulischen Druckmittelspeichergrößen - Volumenstrom und Druck - durch die Auslegung des den Druckmittelspeicher entladenden Ventils als Proportionalventil bevorzugt erfolgt. Damit lassen sich gleichzeitig die an dem Ventil anfallenden Drosselverluste zur Steuerung der Systemgrößen mit heranziehen.In general, the implementation of a parallel hybrid according to the invention in the outlined frame can be based on a resistance or displacement control, wherein the adaptation of the hydraulic pressure fluid storage variables - volume flow and pressure - by the interpretation of the Pressure fluid accumulator discharging valve as a proportional valve is preferred. At the same time, the throttle losses incurred at the valve can be used to control the system variables.

Die Ansteuerung des Prioritätsventils erfolgt in einem besonders bevorzugten Ausführungsbeispiel durch den Einsatz von Drucksensoren, wodurch die Auf- und Entladungsphase des Druckmittelspeichers als auch eine Fördervolumenverstellung einer als variable Druckmittelpumpe gebildeten Druckmittelquelle für die Verbraucher und den Druckmittelspeicher erfolgen. Ein erster Drucksensor stellt ein Signal, das den Lastdruck des Verbrauchers widerspiegelt, bereit, ein zweiter Drucksensor bildet einen aktuellen Speicherdruck des Druckmittelspeichers ab, während ein dritter Drucksensor den Fluiddruck an der Hochdruckseite der Druckmittelpumpe abbildet. Durch die Integration der drei Drucksensoren kann eine bedarfsgerechte Volumenstromversorgung in Abhängigkeit der jeweiligen Verbraucher realisiert werden.The control of the priority valve is carried out in a particularly preferred embodiment by the use of pressure sensors, whereby the charge and discharge phase of the accumulator and a delivery volume adjustment of a pressure medium source formed as a variable pressure medium pump for the consumer and the accumulator. A first pressure sensor provides a signal reflecting the load pressure of the consumer, a second pressure sensor maps a current accumulator pressure of the accumulator, while a third pressure sensor depicts the fluid pressure on the high pressure side of the pressure medium pump. By integrating the three pressure sensors, a demand-based volume power supply can be realized as a function of the respective consumer.

Besonders bevorzugt ist das Prioritätsventil als 3/2-Stetigventil auszubilden, dessen Funktionalität einer 3-Wege-Stromregeleinheit ähnelt, die bevorzugt eine beidseitige hydraulische Ansteuerung erfährt, beispielsweise durch einen Drucksensor, der den Druckmittelspeicherladezustand abbildet und den Fluiddruck an der Hochdruckseite der Druckmittelpumpe erfaßt. Der Druckmittelspeicher läßt sich in an sich bekannter Weise als Kolben-, Blasen- oder Membranspeicher ausgestalten. Sofern 2/2-Stetigventile als herkömmliche Prioritätsventile eingesetzt werden, können diese durch Kaskadierung um Schaltstellungen sinnfällig erweitert werden. Anstelle der genannten 3-Wege-Stromregeleinheit kann auch eine sonstige Mehrwege-Stromregeleinheit treten. Insgesamt bleibt aber festzuhalten, dass das Prioritätsventil als Stetigventil auszubilden ist, dessen Funktionalität einer Mehrwege-Stromregeleinheit ähnelt.Particularly preferably, the priority valve is designed as a 3/2 continuous valve whose functionality is similar to a 3-way flow control unit which preferably experiences a double-sided hydraulic actuation, for example by a pressure sensor which maps the pressure medium storage charge state and detects the fluid pressure on the high pressure side of the pressure medium pump. The accumulator can be configured in a conventional manner as a piston, bubble or diaphragm accumulator. If 2/2-way valves are used as conventional priority valves, they can be expanded by cascading to switch positions obvious. Instead of the aforementioned 3-way flow control unit can also occur another multi-way flow control unit. Overall, however, it should be noted that the priority valve is designed as a continuous valve whose functionality is similar to a multi-way flow control unit.

Bei einem besonders bevorzugten Ausführungsbeispiel weist der Druckmittelspeicher einen minimalen Betriebsdruck von etwa 60 bar und einen maximalen Betriebsdruck von etwa 350 bar auf. Bevorzugt liegt sein Speichervolumen bei insgesamt 20 I. Die erfindungsgemäße Lösung ist weiter dadurch charakterisiert, dass die Speicherladung in Fluidrichtung gesehen über eine Speicherladeschaltung nach dem Prioritätsventil und einer Einspeisung über ein Einspeiseventil als weiteres Ventil vor dem Prioritätsventil erfolgt.In a particularly preferred embodiment, the accumulator has a minimum operating pressure of about 60 bar and a maximum operating pressure of about 350 bar. Preferably, its storage volume is a total of 20 I. The solution according to the invention is further characterized in that the storage charge takes place in the fluid direction via a storage charging circuit after the priority valve and a feed via a feed valve as a further valve before the priority valve.

Die Verbraucher können ein Kühlgebläse und/oder einen Steuerungsantrieb und/oder eine hydraulische Hilfskraftlenkung und/oder eine Arbeitshydraulik etc. sein, wobei in Abhängigkeit von der Maschinen-Betriebsphase ein wiederholtes, kurzzeitiges Abschalten der Verbraucher oder ein zeitliches Verschieben des Zuschaltvorganges der Verbraucher in Relation zu einer Fahrhydraulik der Arbeitsmaschine denkbar ist. Das 3-Wege-Stromregelventil als Prioritätsventil sorgt in Abhängigkeit von seiner Schalt- oder Schiebeposition für eine hydraulische Energieversorgung der parallel geschalteten Verbraucher, wie Druckmittelspeicher und hydraulischer Hilfskraftlenkung oder Fremdkraftlenkung. In Abhängigkeit der abzurufenden hydraulischen Energien kann es zweckmäßig sein, mehr als einen Druckmittelspeicher in der hydraulischen Anlage vorzusehen.The consumers may be a cooling fan and / or a control drive and / or a hydraulic power steering and / or a working hydraulics, etc., depending on the machine operating phase, a repeated, short-term shutdown of the consumer or a time shift of the Zuschaltvorganges the consumer in relation to a driving hydraulics of the working machine is conceivable. The 3-way flow control valve as a priority valve provides depending on its switching or sliding position for a hydraulic power supply of the parallel-connected consumers, such as accumulator and hydraulic power steering or power steering. Depending on the hydraulic energy to be retrieved it may be expedient to provide more than one accumulator in the hydraulic system.

Im Folgenden wird die erfindungsgemäße hydraulische Anlage anhand verschiedener Ausführungsbeispiele nach der Zeichnung näher erläutert. Dabei zeigen in prinzipieller und nicht maßstäblicher Darstellung die

Fig. 1
ein schematisches Schaltbild einer hydraulischen Anlage mit paralleler Hybridisierung der Druckmittelversorgung von verschiedenen Verbrauchern in ihrem grundsätzlichen Aufbau;
Fig. 2
ein schematisches Schaltbild einer hydraulischen Anlage mit paralleler Hybridisierung der Druckmittelversorgung von verschiedenen Verbrauchern und einer automatischen, bedarfsgerechten Ansteuerung des Prioritätsventils und des weiteren Ventils für die Entladung des Druckmittelspeichers;
Fig. 3
ein schematisches Schaltbild einer hydraulischen Anlage gemäß der Darstellung nach der Fig. 1 bei einem Ladevorgang des Druckmittelspeichers;
Fig.4
ein schematisches Schaltbild einer hydraulischen Anlage gemäß der Darstellung nach der Fig. 1 beim Entladevorgang des Druckmittelspeichers und verschiedener Einspeisemethoden des Druckmittels in das System;
Fig. 5
ein schematisches Schaltbild einer hydraulischen Anlage gemäß der Darstellung nach der Fig. 1 mit Rückschlagventilen in den Verbindungsleitungen zu dem Druckmittelspeicher;
Fig. 6
ein schematisches Schaltbild einer hydraulischen Anlage gemäß der Darstellung nach der Fig. 1 mit in dem Ventil zur Entladung des Druckmittelspeichers integrierter Druckwaagenfunktion;
Fig. 7
ein schematisches Schaltbild einer hydraulischen Anlage gemäß der Darstellung nach der Fig. 1 mit in dem Ventil zur Entladung des Druckmittelspeichers integrierter Stromregler-Funktion;
Fig. 8
ein schematisches Schaltbild einer hydraulischen Anlage gemäß der Darstellung nach der Fig. 1 mit in dem Ventil zur Entladung des Druckmittelspeichers integrierter Druckminderer-Funktion;
Fig. 9
ein schematisches Schaltbild einer hydraulischen Anlage gemäß der Darstellung nach der Fig. 1, bei der bei der Entladung des Druckmittelspeichers eine Niederdruckseite der Druckmittelpumpe mit Druckmittel beaufschlagt ist;
Fig. 10
ein schematisches Schaltbild einer hydraulischen Anlage gemäß der Darstellung nach der Fig. 1 mit weiterer Verallgemeinerung des grundsätzlichen Funktionsprinzips in dem Sinne, dass ein mittels einer Verbrennungskraftmaschine antreibbarer Energiewandler eine Einspeiseenergie liefert oder diese von einer angeschlossenen Komponente abrufen kann.
In the following, the hydraulic system according to the invention will be explained in more detail with reference to various embodiments according to the drawing. This show in principle and not to scale representation of the
Fig. 1
a schematic diagram of a hydraulic system with parallel hybridization of the pressure medium supply of various consumers in their basic structure;
Fig. 2
a schematic diagram of a hydraulic system with parallel hybridization of the pressure medium supply of different consumers and an automatic, demand-driven control of the priority valve and the other valve for the discharge of the pressure fluid reservoir;
Fig. 3
a schematic diagram of a hydraulic system as shown in the Fig. 1 during a loading process of the pressure medium reservoir;
Figure 4
a schematic diagram of a hydraulic system as shown in the Fig. 1 during the discharge process of the accumulator and various feed methods of the pressure medium in the system;
Fig. 5
a schematic diagram of a hydraulic system as shown in the Fig. 1 with check valves in the connecting lines to the accumulator;
Fig. 6
a schematic diagram of a hydraulic system as shown in the Fig. 1 with in the valve for discharging the accumulator integrated pressure compensator function;
Fig. 7
a schematic diagram of a hydraulic system as shown in the Fig. 1 with in the valve for discharging the accumulator integrated flow control function;
Fig. 8
a schematic diagram of a hydraulic system as shown in the Fig. 1 with in the valve to Discharge of the accumulator integrated pressure reducer function;
Fig. 9
a schematic diagram of a hydraulic system as shown in the Fig. 1 in which a low-pressure side of the pressure medium pump is subjected to pressure medium during the discharge of the pressure medium reservoir;
Fig. 10
a schematic diagram of a hydraulic system as shown in the Fig. 1 with further generalization of the fundamental principle of operation in the sense that an energy converter which can be driven by means of an internal combustion engine supplies a feed-in energy or can call it from a connected component.

In Fig. 1 ist in einem schematischen Schaltbild teilweise eine hydraulische Anlage 1 für eine Baumaschine dargestellt. Die hydraulische Anlage 1 wird von einer als Motoreinheit ausgebildeten Verbrennungskraftmaschine 2 (VKM), beispielsweise in Form eines Dieselmotors, mit einer vorgebbaren effektiven Antriebsleistung angetrieben, beispielsweise mit einer Antriebsleistung von 56 kW, wobei für einen nicht näher dargestellten Fahrantrieb 12 der Baumaschine ein Energiewandler (Druckmittelpumpe, Getriebe, E-Motor) angetrieben ist, sowie des weiteren eine verstellbare Druckmittelpumpe 13 angetrieben ist sowie des weiteren eine als Pumpen-Motoreinheit einsetzbare Druckmittelpumpe 3, mit der die einzelnen Verbraucher der hydraulischen Anlage 1 mit Druckmittel 5 versorgt werden. Das genannte Nutzfahrzeug weist in den in allen Figuren gezeigten Ausführungsbeispielen mehrere hydraulische, insbesondere hydrostatische Antriebssysteme auf in Form einer Lenkhydraulik 4, einer Steuer- und Speisehydraulik 8, gegebenenfalls noch unter Einbezug einer Kühlhydraulik, sowie einer Fahrhydraulik 12, die nicht näher dargestellt ist und von der einstellbaren Druckmittelpumpe 13, wie dargelegt, versorgt ist. Diese Systeme können in Abhängigkeit von ihrer Grundstruktur teilweise unabhängig voneinander ihre Funktion ausüben.In Fig. 1 is shown in a schematic diagram partially a hydraulic system 1 for a construction machine. The hydraulic system 1 is driven by a designed as a motor unit internal combustion engine 2 (VKM), for example in the form of a diesel engine, with a predetermined effective drive power, for example, with a drive power of 56 kW, for a non-illustrated drive 12 of the construction machine, an energy converter ( Pressure medium pump, transmission, electric motor) is driven, and further an adjustable pressure medium pump 13 is driven and further usable as a pump motor unit pressure medium pump 3, with which the individual consumers of the hydraulic system 1 are supplied with pressure medium 5. Said commercial vehicle has in the embodiments shown in all figures, several hydraulic, especially hydrostatic drive systems in the form of a steering hydraulic 4, a control and feeding 8, possibly even with the inclusion of a cooling hydraulics, and a drive hydraulics 12, which is not shown in detail and the adjustable Pressure medium pump 13, as stated, is supplied. Depending on their basic structure, these systems can, in some cases, function independently of each other.

Stromauf ist auf der Hochdruckseite der Druckmittelpumpe 3 ein Prioritätsventil 7 als Stetigventil, vorzugsweise als 3/2-Stetigventil ausgebildet, zwischen dem ersten Verbraucher 4 als Teil der Lenkhydraulik und der Druckmittelpumpe 3 zwischengeschaltet. Ein weiterer, zweiter Verbraucher 8 als Teil der Steuer- und Speisehydraulik ist in Parallelanordnung zum ersten Verbraucher 4 an die Ausgangsseite des Prioritätsventils 7 angeschlossen. Ein Druckmittelspeicher 6 ist in gleicher Weise in Parallelanordnung ausgangsseitig mit dem Prioritätsventil 7 verbunden, also in gleicher Weise wie der Verbraucher 4 und der zweite Verbraucher 8. Der Druckmittelspeicher 6 ist zur Abdeckung kurzzeitiger, dynamischer Leistungsspitzen erforderlich, um bei der Verbrennungskraftmaschine 2 unterhalb der gewünschten, vorgebbaren Leistungsgrenze zu bleiben. Das Mehrwege-Stromregelventil, besonders bevorzugt als 3/2-Wege-Stromregelventil aufgebaute Prioritätsventil 7 sorgt in Abhängigkeit von seiner Schieberposition für eine hydraulische Energieversorgung der parallel geschalteten Verbraucher 4 und 8 sowie des Druckmittelspeichers 6.Upstream is on the high pressure side of the pressure medium pump 3, a priority valve 7 as a continuous valve, preferably designed as a 3/2 continuous valve, interposed between the first load 4 as part of the steering hydraulic and the pressure medium pump 3. Another second consumer 8 as part of the control and supply hydraulics is connected in parallel to the first consumer 4 to the output side of the priority valve 7. A pressure fluid reservoir 6 is connected in the same way in parallel arrangement on the output side with the priority valve 7, ie in the same way as the consumer 4 and the second consumer 8. The pressure fluid reservoir 6 is required to cover short-term, dynamic power peaks to below the desired in the internal combustion engine 2 to stay within the stipulated performance limit. The multi-way flow control valve, particularly preferably constructed as a 3/2-way flow control valve priority valve 7 provides in dependence on its slide position for a hydraulic power supply of the parallel-connected loads 4 and 8 and the accumulator 6.

Für die Realisierung der Entladungsphase des Druckmittelspeichers 6 kommt ein weiteres Ventil 9 zum Einsatz. Das weitere Ventil 9 kann, wie dies die Fig. 6 zeigt, gleichzeitig in Abhängigkeit der Last am Verbraucher ein automatisches, hydraulisches Drucksignal vonseiten des Prioritätsventils 7 erhalten. Durch diesen Aufbau ist es beispielsweise möglich, durch den Druckmittelspeicher 6 kurzzeitige Bedarfsanforderungen der Ventileinheit unabhängig vom Maschinenbedarfszyklus abzudecken. In gleicher Weise kann ein energiesparender Betrieb anderer Verbraucher, die mit dem Prioritätsventil 7 ansteuerbar sind, aufrechterhalten werden. Aus sicherheitsrelevanten Aspekten ist die Lenkung 4 gegenüber dem Druckmittelspeicher 6 und dem weiteren Verbraucher 8 priorisiert, d.h. eine Aufladung des Druckmittelspeichers 6 oder der sonstigen nicht sicherheitsrelevanten Verbraucher 8 erfolgt nur dann, wenn keine Lenkansteuerung vorgenommen wird oder der für den Lenkvorgang benötigte Bedarf über das Prioritätsventil 7 in jedem Fall sichergestellt ist.For the realization of the discharge phase of the accumulator 6 another valve 9 is used. The other valve 9 can, as the Fig. 6 shows, at the same time receive an automatic, hydraulic pressure signal from the priority valve 7, depending on the load on the consumer. By means of this structure, it is possible, for example, to cover short-term requirements of the valve unit by the pressure medium reservoir 6 independently of the machine requirement cycle. In the same way, an energy-saving operation of other consumers, which are controllable with the priority valve 7, be maintained. For safety-relevant aspects, the steering 4 is opposite the accumulator 6 and the other consumer 8 prioritized, that is, a charge of the accumulator 6 or the other non-safety-relevant consumer 8 only takes place when no steering control is made or the need for the steering operation needs over the priority valve 7 is ensured in each case.

Wie die Fig. 2 des weiteren zeigt, ist es vorteilhaft, in Abhängigkeit von einem Signal eines ersten Drucksensors S1, der einen Lastdruck eines Verbrauchers abbildet, von einem Signal eines zweiten Drucksensors S2, der den aktuellen Speicherdruck des Druckmittelspeichers 6 abbildet, und von einem Signal eines dritten Drucksensors S3, der den Druck an der Hochdruckseite der Druckmittelpumpe 3 beschreibt, über eine Steuer- und/oder Regelungseinrichtung 11 (ECU) die Aufladungs- und Entladungsphase des Druckmittelspeichers 6 durchzuführen. Fig. 3 wiederum zeigt eine Betriebsphase der hydraulischen Anlage 1, in der der Druckmittelspeicher 6 aufgeladen wird. Gleichzeitig sind die verschiedenen Verbraucher 4,8 in Betrieb und werden mit Druckmittel 5 in benötigtem Umfang versorgt. Im übrigen hat die Regelungseinrichtung 11 (ECU) das Prioritätsventil 7 für dessen Betrieb anzusteuern.As the Fig. 2 Furthermore, it is advantageous, in response to a signal of a first pressure sensor S1, which maps a load pressure of a consumer, by a signal of a second pressure sensor S2, which maps the current accumulator pressure of the accumulator 6, and by a signal of a third pressure sensor S3 , which describes the pressure at the high pressure side of the pressure medium pump 3, via a control and / or regulating device 11 (ECU) perform the charging and discharging phase of the pressure medium reservoir 6. Fig. 3 again shows an operating phase of the hydraulic system 1, in which the accumulator 6 is charged. At the same time, the various consumers are 4.8 in operation and are supplied with pressure medium 5 in the required extent. Moreover, the control device 11 (ECU) has the priority valve 7 to control its operation.

Grundsätzlich sind für die Entladungsphase und deren Energieeinspeisung von dem Druckmittelspeicher 6 in die hydraulische Anlage 1 zwei Konzepte realisierbar. Zum einen läßt sich eine Art serieller Hybrid darstellen, d.h. die Energieentladung findet innerhalb des Hydrostaten statt, wie dies der mit "hydraulisch" bezeichnete Pfeil in Fig. 4 wiedergibt, oder die Energieentladung findet unter Bildung und Umwandlung in mechanische Energie als sog. Parallel-Hybrid statt, wie dies der mit "mechanisch" bezeichnete Pfeil in Fig. 4 gleichfalls verdeutlicht. In Fig. 4 ist im übrigen die Situation bei der Energieeinspeisung auf der Pumpen-Hochdruckseite verdeutlicht, die eine direkte Verbraucherunterstützung widerspiegelt und beispielsweise eine höhere Anfahrdynamik bzw. Versorgungsdynamik für einen Verbraucher bewirken kann oder zu einer zumindest teilweisen Entlastung der Verstellpumpe 3 und der Verbrennungskraftmaschine VKM führt. Grundsätzlich ist auch eine Entladung des Druckmittelspeichers 6 auf der Niederdruckseite der Druckmittelpumpe 3 möglich, so dass eine Energiezufuhr auf der Pumpensaugseite vorliegt, wodurch kurzzeitig das Antriebsmoment der Pumpe 3 verringert werden kann. Die für die Druckmittelversorgung der hydraulischen Anlage 1 verantwortliche Druckmittelpumpe 3 ist als Pumpen-Motoreinheit ausgebildet, so dass bei einer entsprechenden Verschwenkung, beispielsweise eines Kurvenringes in der Druckmittelpumpe 3, der zusammen mit den darin rotierend angeordneten Verdrängerelementen Pumpenkammern (nicht dargestellt) definiert, beim Entladungsvorgang des Druckmittelspeichers 6 mechanische Energie gewonnen werden kann, um dergestalt eine Parallel-Hybridlösung zu realisieren.In principle, two concepts can be implemented for the discharge phase and its energy supply from the accumulator 6 into the hydraulic system 1. On the one hand, a kind of serial hybrid can be represented, ie the energy discharge takes place within the hydrostat, as is indicated by the arrow "hydraulically" in FIG Fig. 4 or the energy discharge takes place under formation and conversion into mechanical energy as a so-called parallel hybrid, as the arrow labeled "mechanical" in FIG Fig. 4 also clarified. In Fig. 4 Incidentally, the situation in the energy supply on the pump high-pressure side is clarified, which reflects a direct consumer support and, for example, a higher starting dynamics or supply dynamics for a consumer can cause or leads to an at least partial relief of the variable displacement pump 3 and the internal combustion engine VKM. In principle, a discharge of the accumulator 6 on the low pressure side of the pressure medium pump 3 is possible, so that an energy supply is present on the pump suction, whereby the drive torque of the pump 3 can be reduced for a short time. The responsible for the pressure medium supply of the hydraulic system 1 pressure medium pump 3 is designed as a pump motor unit, so that at a corresponding pivoting, for example, a cam ring in the pressure medium pump 3, together with the rotatably arranged therein displacement chambers pump chambers (not shown) defined during the discharge process of the accumulator 6 mechanical energy can be obtained in order to realize such a parallel hybrid solution.

Neben einer Energieeinspeisefunktion bietet dies weiterhin die Möglichkeit einer Bremsenergiespeicherung. Wird die Bremsenergie in den Speicher eingespeist, ermöglicht dies die Entlastung der Betriebsbremse.
Wie Fig. 5 zeigt, können diesbezügliche Rückschlagventile 14 in der Versorgungs- und Einspeiseleitung von bzw. zum Druckmittelspeicher 6 vorgesehen sein, wobei das Rückschlagventil 14 zwischen Druckmittelpumpe 3 und Hydrospeicher die Funktion des weiteren Ventils 9 übernimmt. Des weiteren kann das Ventil 9 zur Entladung des Druckmittelspeichers 6 eine Druckwaagenfunktion 10 (vgl. Fig. 6), eine Stromregelfunktion (vgl. Fig. 7) oder eine Druckminderfunktion (vgl. Fig. 8) mit umfassen.
In addition to an energy feed function, this also offers the possibility of braking energy storage. The braking energy is fed into the memory, this allows the relief of the service brake.
As Fig. 5 shows that relevant check valves 14 may be provided in the supply and feed line from or to the accumulator 6, wherein the check valve 14 between the pressure medium pump 3 and hydraulic accumulator takes over the function of the other valve 9. Furthermore, the valve 9 for discharging the accumulator 6, a pressure compensator function 10 (see. Fig. 6 ), a current control function (cf. Fig. 7 ) or a pressure reducing function (cf. Fig. 8 ).

Die in den Ausführungsbeispielen genannten Verbraucher 4,8 können verständlicherweise anderer Natur sein, beispielsweise braucht der erste Verbraucher 4 nicht die Lenkhydraulik zu betreffen. Ferner könnten beide Verbraucher 4,8 beide einen Lenkkreis betreffen. So könnte der zweite Verbraucher 8 als hydraulische Fremdkraftlenkung ausgebildet sein und der Verbraucher 4 eine übliche Hilfs-Lenkhydraulik bilden. Allen Lösungen gemeinsam und von besonderer Bedeutung ist jedoch, dass die Speicherladung über eine Speicherladeschaltung nach dem Prioritätsventil 7 und die Einspeisung über das Einspeiseventil 9 vor dem Prioritätsventil 7 in jeweiliger Fluidrichtung gesehen erfolgt.The consumer 4,8 mentioned in the exemplary embodiments can understandably be of a different nature, for example the first consumer 4 does not need to concern the steering hydraulics. Furthermore, both consumers 4.8 could both affect a steering circuit. Thus, the second consumer 8 could be designed as a hydraulic power steering system and the consumer 4 form a conventional auxiliary steering hydraulics. All solutions common and of particular importance, however, is that the storage charge takes place via a storage charging circuit after the priority valve 7 and the feed via the feed valve 9 before the priority valve 7 in the respective fluid direction.

In der Fig. 9 ist eine hydraulische Schaltplanlösung dargestellt, bei der bei der Entladung des Druckmittelspeichers 6 eine Niederdruckseite der Druckmittelpumpe 3 mit Druckmittel 5 beaufschlagt ist. Die dahingehende Fig. 9 sowie die verallgemeinernde Lösung nach der Fig. 10 können anstelle eines Fahrantriebes 12 auch allgemein einen Energiewandler aufweisen, wie eine Druckmittelpumpe, ein Getriebe, ein E-Motor und dergleichen mehr.In the Fig. 9 a hydraulic circuit diagram solution is shown in which during the discharge of the accumulator 6, a low pressure side of the pressure medium pump 3 is acted upon by pressure medium 5. The pertinent Fig. 9 and the generalized solution according to the Fig. 10 may also generally have an energy converter, such as a pressure medium pump, a transmission, an electric motor and the like instead of a traction drive 12.

Claims (17)

  1. A hydraulic system, in particular for a utility vehicle such as a construction vehicle, comprising a pressurising medium pump (3) driven by a motor unit, in particular in the form of an internal combustion engine (2), which supplies a first consumer (4) with pressurising medium (5), a pressurising medium accumulator (6) being able to be charged by the pressurising medium pump (3), at least one priority valve (7) controlling the charging of the pressurising medium accumulator (6) and the pressurising medium supply of the consumer (4) dependently upon a current power output of the motor unit, the connection or disconnection of the supply of pressurising medium of the pressurising medium accumulator (6) to the consumer (4) and to a further second consumer (8) being controlled by a further valve (9), the charging of the accumulator taking place via an accumulator charging circuit after the priority valve (7) and the feed.taking place via a feed valve as a further valve (9) before the priority valve (7) as viewed in the direction of fluid flow from the pressurising medium pump (3).
  2. The hydraulic system according to Claim 1, characterised in that no pressurising medium is conveyed by the pressurising medium pump (3) in a connecting phase of the pressurising medium accumulator (6).
  3. The hydraulic system according to Claim 1 or 2, characterised in that the charging of the pressurising medium accumulator (6) takes place in a stationary machine running phase of the motor unit.
  4. The hydraulic system according to any of Claims 1 to 3, characterised in that upon discharging the pressurising medium accumulator (6) a high pressure side of the pressurising medium pump (3) is acted upon with pressurising medium (5).
  5. The hydraulic system according to any of Claims 1 to 3, characterised in that upon discharging the pressurising medium accumulator (6) a low pressure side of the pressurising medium pump (3) is acted upon with pressurising medium (5).
  6. The hydraulic system according to any of Claims 1 to 3, characterised in that the pressurising medium pump (3) is in the form of a pump motor unit and upon discharging the pressurising medium accumulator (6) hydraulic energy is converted into mechanical energy.
  7. The hydraulic system according to any of Claims 1 to 6, characterised in that the further valve (9) for controlling the discharging of the pressurising medium accumulator (6) is a proportional valve which controls the volumetric flow and/or the pressure of the pressurising medium (5).
  8. The hydraulic system according to any of Claims 1 to 7, characterised in that the priority valve (7) is activated dependently upon a signal of a first pressure sensor (S1) that reproduces the load pressure of the consumer (4) and/or upon a signal of a second pressure sensor (S2) that reproduces the accumulator pressure of the pressurising medium accumulator (6) and/or upon a signal of a third pressure sensor (S3) that describes the pressure on the high pressure side of the pressurising medium pump (3).
  9. The hydraulic system according to any of Claims 1 to 8, characterised in that the priority valve (7) is in the form of a continuously adjustable valve.
  10. The hydraulic system according to any of Claims 1 to 9, characterised in that the further valve (9) for discharging the pressurising medium accumulator (6) comprises a pressure compensator (10).
  11. The hydraulic system according to any of Claims 1 to 10, characterised in that the further valve (9) for discharging the pressurising medium accumulator (6) comprises a flow regulating function.
  12. The hydraulic system according to any of Claims 1 to 11, characterised in that the pressurising medium accumulator (6) is a piston or bladder or diaphragm accumulator.
  13. The hydraulic system according to any of Claims 1 to 12, characterised in that the pressurising medium accumulator (6) has a maximum operating pressure of 350 bar and a minimum operating pressure of 60 bar.
  14. The hydraulic system according to any of Claims 1 to 13, characterised in that the further valve (9) for discharging the pressurising medium accumulator (6) is activated by a control and/or regulation device (11) dependently upon the load pressure.
  15. The hydraulic system according to any of Claims 1 to 14, characterised in that consumers (4, 8) of the hydraulic system (1) are steering hydraulics, working hydraulics and control and feed hydraulics.
  16. The hydraulic system according to Claim 15, characterised in that the pressurising medium pump (3) is swivelled back with a full pressurising medium accumulator (6) and with the vehicle driving in a straight line.
  17. The hydraulic system according to any of Claims 1 to 16, characterised in that the hydraulic system (1) comprises two or more pressurising medium accumulators (6).
EP20100004301 2009-05-13 2010-04-22 Hydraulic assembly Active EP2251549B1 (en)

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CN102155440A (en) * 2011-04-06 2011-08-17 上海朝田实业有限公司 Hydraulic energy-saving motor device of hydraulic pump station
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DE102012208938A1 (en) * 2012-05-29 2013-12-05 Robert Bosch Gmbh Hydraulic control device for mobile working machine e.g. hydraulic excavators, has delivery pressure regulator that includes shuttle valve connected to steering pressure and pump pressure, such that pressure set-point is derived
EP2792522B1 (en) * 2013-04-15 2017-12-27 HAWE Hydraulik SE Hybrid transmission system
CN105545135B (en) * 2015-02-28 2017-08-25 北京航空航天大学 Opportunity of combat internal weapon bays hatch door transient state actuating system based on fixed displacement motor principle
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DE102017122175A1 (en) * 2017-09-25 2019-03-28 Claas Tractor Sas Agricultural working machine

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CN105805063A (en) * 2015-02-28 2016-07-27 北京航空航天大学 New-principle cabin door transient actuating system based on variable displacement motor
CN105805063B (en) * 2015-02-28 2019-05-21 北京航空航天大学 New principle hatch door transient state actuating system based on variable displacement motor

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