DE102011104919A1 - Powertrain for vehicle e.g. industrial lorry, has hydraulic machine formed by two hydraulic motors, where input side of one of motors is connected with pressure reservoir, and output side of motor is connected with container - Google Patents

Abstract

The powertrain (1) has a working hydraulic system (4) including a hydraulic pump (7) that is operated by an internal combustion engine (2) i.e. diesel engine. A hydraulic pressure reservoir (20) is connected with a hydraulic machine (21) for performing an energy recovery and torque outputting process. The hydraulic machine is formed by two hydraulic motors (22a, 22b). An input side of one of the motors is connected with the pressure reservoir, and an output side of the motor is connected with a container (9). The motor is driven from the reservoir to the container along a conveying direction.

Description

The invention relates to a drive train of a vehicle, in particular a mobile work machine, with an internal combustion engine and driven by the internal combustion engine drive and driven by the engine working hydraulic system, the working hydraulic system having at least one driven by the internal combustion engine hydraulic pump and wherein the drive train with a hydraulic pressure accumulator and a hydraulic machine in communication with the pressure accumulator for energy recovery and a torque output in the drive train is provided.

Mobile self-propelled machines, especially industrial trucks, agricultural machinery, forestry machinery and construction equipment, such as excavators, wheeled and telescopic loaders, tractors, combine harvester, forage harvester, sugar beet or potato harvester, have a drive train with an internal combustion engine, a traction drive and a working hydraulic system for the working functions of Working machine drives. To supply the working hydraulic system at least one of the internal combustion engine driven hydraulic pump is provided.

It is already known to provide such a drive train with a hydraulic pressure accumulator and a connected to the pressure accumulator hydraulic machine. By loading the pressure accumulator during a braking operation of the traction drive and / or when lowering a load, a recuperation of kinetic energy of the vehicle or potential energy of a raised load can take place. By operating the hydraulic machine with the pressure medium from the pressure accumulator, in addition to the internal combustion engine, a torque can be delivered to the drive train. The hydraulic machine driven by the pressure accumulator thus forms a hydrostatic auxiliary drive of the drive train and in particular makes possible a booster drive in which, in the event of a power requirement, the internal combustion engine is assisted by an additional torque output by the hydraulic machine into the drive train. The energy recovered during braking of the vehicle in the pressure accumulator can, for example, be made available to the drive train by the hydraulic machine during a renewed acceleration of the working machine, so that the energy for accelerating the working machine no longer has to be provided exclusively by the internal combustion engine.

The hydrostatic auxiliary drive formed by the pressure accumulator and the hydraulic machine thus makes it possible to reduce the fuel consumption of the internal combustion engine. In addition, the internal combustion engine can be reduced in its performance by the hydrostatic auxiliary drive. Such a downsizing of the internal combustion engine leads to advantages, in particular in the observance of legal exhaust gas regulations of the internal combustion engine.

From the generic DE 10 2008 028 547 A1 is a generic drive train of a mobile machine with a hydraulic auxiliary drive known in which an energy recovery takes place by braking a hydraulic accumulator during braking. The connected to the accumulator hydraulic machine is designed as operated in the open circuit, in the axial direction of a small space having radial piston pump formed as a working hydraulic pump of the working hydraulic system and can be operated as a pump and a motor. However, such, operable as a pump and motor radial piston pump has a high construction cost, since appropriate valves or control recesses are required to control the Druckmittelzu- and outflow.

From the DE 32 47 335 A1 is a drive train with a hydraulic auxiliary drive known, which is formed by a hydraulic accumulator and the open-circuit operated hydraulic pump. About the working hydraulic pump, the pressure accumulator can be filled with pressure medium when braking the machine and an energy recovery done. For introducing an additional torque into the drive train, the pressure accumulator is connected to the suction side of the working hydraulic pump, so that the working hydraulic pump works as a motor. Such, operated in the open circuit working hydraulic pump, for example, an axial piston pump with a constant or adjustable delivery volume, which is in communication with the intake port to the container, is usually designed for a high Sauggrenzdrehzahlen. The intake port with the intake passage in this case has a correspondingly large cross section, wherein in an engine operation in which the pressure accumulator is connected to the intake port of the working hydraulic pump, usually the housing does not have sufficient strength for pressures to the desired additional torque in the To achieve powertrain. In addition, when connecting the suction port of the working hydraulic pump to the pressure accumulator during engine operation of the working hydraulic pump, it is necessary to form the intake port and the intake port high pressure resistant, thereby further increasing the construction cost.

From the DE 10 2008 021 889 A1 and the WO 2007/071362 A1 hydraulic auxiliary drives are known in the work machine, in which an energy recovery takes place in a pressure accumulator at a lowering of a load or in a braking operation of the working machine, which can be fed via an open-circuit operated hydraulic machine as additional torque in the drive train. The hydraulic machine is designed here as a hydraulic machine, which is operated as a pump and as a motor. The hydraulic machine can be operated in both conveying directions and, for this purpose, is designed as a swashplate-type axial piston machine that can be swiveled over zero in both directions. However, operated in the open circuit and over zero in both directions pivotable axial piston machine, which is operable as a pump and a motor, but has a high construction cost. In addition, an adjustable axial piston pump has a high space requirement in the longitudinal direction.

The present invention has for its object to provide a drive train of the type mentioned available, in which a hydraulic auxiliary drive for additional torque output in the drive train with low construction costs and can be created in a cost effective manner.

This object is achieved in that the hydraulic machine is formed by at least one hydrostatic hydraulic motor, the input side is connected to the hydraulic pressure accumulator, the output side is in communication with a container and is operated exclusively in a conveying direction of the pressure accumulator to the container. An in addition to the working hydraulic system supplying hydraulic pump and the traction drive arranged in the drive train hydraulic motor which is driven with pressurized pressure medium from a hydraulic pressure accumulator and exclusively in a conveying direction of the pressure accumulator to the container and thus exclusively as a motor for applying an additional drive torque in the Powertrain is used, it allows at low construction cost, in conjunction with a hydraulic pressure accumulator to introduce an additional torque in the drive train as a boost drive and apply the desired torque to reduce the power of the engine and thus to enable downsizing and to achieve fuel savings , An exclusively as a motor in a conveying direction from the accumulator to the vessel operated hydrostatic hydraulic motor in the context of the invention is a hydraulic motor, the output side is in communication with a container and promotes pressure in a drive by the running internal combustion engine without utilization in the container. A conveying direction from the container into the pressure accumulator for charging the pressure accumulator is not provided with the hydraulic motor according to the invention. Such a hydraulic motor has a simple structure and thus enables in conjunction with the hydraulic pressure accumulator hydrostatic auxiliary drive of the drive train with low construction costs and low production costs.

According to a preferred embodiment of the invention, the at least one hydraulic motor is designed as a hydraulic starter for starting the internal combustion engine in a start-stop function. During an idling operation in which the traction drive and the working hydraulic system are not actuated and thus no torque request is requested from the internal combustion engine, the internal combustion engine is operated at a lower idling speed. Such idling operation takes place during work breaks or during work stoppages. In order to reduce fuel consumption during work breaks or work stoppages, a so-called start-stop function can be provided for the internal combustion engine, in which the unloaded combustion engine is switched off during work breaks or work stoppages and automatically restarted at a torque request by a work function or the traction drive. The shutdown and the subsequent restart of the engine takes place here even at relatively short idle times, so that the starting process of the engine occurs frequently in operation of the machine. This places high demands on the starting device of the internal combustion engine in terms of fatigue strength and the provision of the required starting energy for starting the internal combustion engine. In addition, in mobile work machines during the starting process of the internal combustion engine arranged in the drive train hydraulic pump of the working hydraulic system requires additional energy. Existing electromotive, gear-reduced starting devices of the internal combustion engine are therefore not suitable to produce a start-stop function with appropriate fatigue strength and the required starting energy in an economical manner. The inventive, at least one coupled to the drive train or integrated, driven by the pressure fluid from the pressure accumulator hydraulic motor makes it possible to start the engine with the coupled hydraulic pump of the working hydraulic system from a standstill and the required torque and the required starting energy for the internal combustion engine with low construction costs apply, so that a start-stop function of the internal combustion engine with the required fatigue strength can be provided with low construction costs.

The associated with the pressure accumulator, at least one hydraulic motor, the Hydraulic pump of the working hydraulic system and a primary unit of the traction drive can be arranged according to an advantageous embodiment of the invention on an output shaft of the internal combustion engine. In this case, the at least one hydraulic motor is preferably arranged between the primary unit of the traction drive and the hydraulic pump of the working hydraulic system in the drive train. As a rule, the primary unit of the traction drive for driving by the internal combustion engine is connected directly to the crankshaft of the internal combustion engine. The arrangement of the hydraulic motor of the hydraulic auxiliary drive in the drive train in the axial direction between the primary unit of the traction drive and the hydraulic pump of the working hydraulic system allows a direct and short power flow when applying the additional torque to support the engine when driving the traction drive and / or when applying the additional torque for a Support of the internal combustion engine when driving the hydraulic pump of the working hydraulic system. The arrangement of the at least one hydraulic motor on an output shaft of the internal combustion engine between the primary unit of the traction drive and the hydraulic pump of the working hydraulic system thus allows for a favorable power flow, an additional torque in the drive train for the support of the internal combustion engine when driving the primary unit of the traction drive and the drive of the working hydraulic system initiate. However, the arrangement of the order of the at least one hydraulic motor, the hydraulic pump of the working hydraulic system and the primary unit of the traction drive can be varied.

If the space is limited in the axial longitudinal direction of the drive train, for example, to be saved in a vehicle transverse direction arranged internal combustion engine and drive train, or space in the axial direction of the drive train is provided according to an alternative embodiment of the invention that the at least one hydraulic motor by means of a transmission device is in operative connection with the output shaft of the internal combustion engine, on which the primary unit of the traction drive and the hydraulic pump of the working hydraulic system are arranged. In this case, a parallel arrangement of the at least one hydraulic motor with its output shaft is preferably provided for an output shaft, on which the primary unit of the traction drive and the hydraulic pump of the working hydraulic system are arranged, so that a deaxial integration of the at least one hydraulic motor in the drive train is achieved. The transmission device for coupling the at least one hydraulic motor to the output shaft of the drive train can take place via a simply constructed spur gear with a gear stage or a traction mechanism, for example a chain drive.

The inventive, operated exclusively as a motor at least one hydraulic motor as a hydraulic auxiliary drive in the drive train has no pump operation in a second conveying direction of the container in the pressure accumulator, in which the pressure accumulator can be loaded by appropriate pump operation of the hydraulic motor with pressure medium. In order to allow loading of the pressure accumulator with pressure medium, a charging device is provided according to an advantageous embodiment of the invention.

With particular advantage, according to an advantageous embodiment of the invention, the hydraulic pump of the working hydraulic system is designed as a charging device for charging the pressure accumulator.

With the hydraulic pump of the working hydraulic system can be easily promoted in a brake operation of the vehicle, the primary unit of the traction drive acts as a motor and the hydraulic pump of the working hydraulic system is driven by the primary unit of the traction drive, pressure medium in the pressure accumulator and this charged. With the hydraulic pump of the working hydraulic system as a charging device of the pressure accumulator can thus be easily recuperation of braking energy in the accumulator during a braking operation of the vehicle, which in an acceleration process of the traction drive and / or operation of the hydraulic system by the operation of the at least one hydraulic motor back to Is made available.

Alternatively or additionally, the pressure accumulator can be charged with pressure medium via the hydraulic pump of the working hydraulic system in a simple manner in a drive by the internal combustion engine. In the case of primary-side drive of the hydraulic pump of the working hydraulic system by the internal combustion engine for charging the pressure accumulator, the accumulator can also be charged outside of such recuperation periods, for example while driving, when the working machine is stationary or during working operation, so that periods for filling the pressure accumulator can be used where the combustion engine delivers more power than the consumers lose weight. Moreover, such a charging device makes it possible for the pressure accumulator to be charged with low charging currents over a relatively long period of time, so that an energetically favorable charging operation of the accumulator can be achieved.

Conveniently, the hydraulic pump of the working hydraulic system is operated in the open circuit and as adjustable in the delivery volume hydraulic pump or constant in the delivery volume Hydraulic pump formed. A working hydraulic pump that is preferably adjustable in the delivery volume makes it possible in a simple manner to charge the pressure accumulator selectively with an energy surplus, for example when the vehicle is decelerated by recuperation of kinetic energy or, depending on the operating state, by a drive through the internal combustion engine.

Conveniently, an electrically controllable accumulator charging valve is provided which has a loading position connecting the delivery line of the hydraulic pump of the working hydraulic system with a storage line leading to the pressure accumulator and a blocking position shutting off the connection of the delivery line with the accumulator line. With an electrically controlled accumulator charging valve, the charging process of the accumulator can be controlled in a simple manner.

If according to an advantageous embodiment of the invention, the electrically controlled accumulator charging valve has a discharge position in which the storage line is connected to a guided to the input side of the at least one hydraulic motor connecting line, wherein in the blocking position of the accumulator charging valve, the connection of the storage line is shut off with the connecting line, can be connected to the charging valve in a simple manner in the discharge position of the pressure accumulator with the input side of the at least one hydraulic motor to initiate an additional torque in the drive train and / or to start the engine.

As a hydraulic motor can be provided in the displacement variable displacement motor. The adjusting motor can be configured as an adjusting motor which is infinitely variable in the displacement volume, for example as an axial piston motor or radial piston motor, or as an adjusting motor switchable in the displacement between two different displacement volumes, for example a switchable radial piston motor. By varying the displacement volume, depending on the operating state, the state of charge of the pressure accumulator and / or the torque request of the engine, a different sized supporting torque can be introduced into the drive train to achieve an energetically meaningful support of the engine and an effective reduction of fuel consumption can. In particular when using the hydraulic motor as a hydraulic starter for starting the internal combustion engine for a start-stop function and as a hydraulic auxiliary drive to assist the internal combustion engine during driving and / or during operation of the working hydraulic system can by an adjusting motor or a switchable in the displacement volume hydraulic motor with only a single Hydraulic motor for starting the engine with a large displacement volume high torque can be generated over a short period of time and when assisting the internal combustion engine during operation and / or operation of the working hydraulic system by a reduced displacement volume, a reduced torque can be fed into the drive train to support of the internal combustion engine over a longer period of several seconds to achieve. With such assistance of the internal combustion engine, power peaks and peak loads can be applied, so that the engine can be reduced in power and effective reduction of fuel consumption can be achieved.

Different absorption volumes can also be achieved if, according to an advantageous development of the invention, at least two fixed-speed engines designed as fixed-displacement engines with a constant displacement volume are provided as hydraulic machines. By correspondingly connecting one or both hydraulic motors to the pressure accumulator, a reduced torque can thus be generated over a short period of time or an increased torque in the drive train over a relatively long period of time. Constant motors have a low construction cost and manufacturing effort, so that with two or more hydraulic motors designed as constant motors different absorption volume for a change in torque can be achieved with low construction costs.

The two constant-displacement motors can have the same displacement volume according to one embodiment of the invention.

Special advantages arise when the two constant motors have different displacement volume. As a result, an optimal torque assistance of the internal combustion engine is possible by connecting one or both fixed-displacement engines to the pressure accumulator as a function of the operating state, the charge state of the pressure accumulator and / or the torque request of the internal combustion engine.

By connecting both hydraulic motors or the constant-displacement motor with the larger displacement volume with the pressure accumulator, a sufficiently high torque for starting the internal combustion engine for a start-stop function can be generated in a simple manner.

For the support of the internal combustion engine while driving and / or during actuation of the working hydraulic system, with the connection of only a single hydraulic motor, in particular the constant displacement engine with the smaller displacement volume, and / or both hydraulic motors, the desired torque can be applied to cover power peaks and peak loads, so that the engine can be reduced in performance and an effective reduction of fuel consumption can be achieved. As a result, suitable operating strategies are possible in a simple manner in which the torque specification of the internal combustion engine and / or the acceleration specification of the vehicle can be taken into account.

The torque output via the hydraulic motor in the drive train is expediently carried out during an acceleration process of the traction drive and / or an operation of the working hydraulic system. In such operating states, by assisting the internal combustion engine with the auxiliary hydraulic drive, it is possible to apply power peaks and peak loads, so that the engine can be reduced in power and an effective reduction in fuel consumption can be achieved.

With particular advantage, an electrically actuable control valve is arranged to control the connection of the input side of the hydraulic motor with the pressure accumulator in the connecting line. With such an electrically controllable control valve can be easily controlled by an operation of the hydraulic motor with pressure medium from the pressure accumulator, the torque output in the drive train.

Appropriately, the charging valve and the control valve by means of an electronic control device can be actuated. An electronic control device, in particular an electronic vehicle control, in which corresponding input signals are processed, makes it possible in a simple manner to control the charging process of the pressure accumulator and to use the at least one hydraulic motor as a hydraulic starter and / or to support the internal combustion engine according to suitable operating strategies.

In the function of the at least one hydraulic motor as a hydraulic starter, a rotational speed sensor device for detecting the rotational speed of the internal combustion engine is provided, which is in communication with the electronic control device, wherein the signal of the rotational speed sensor device upon actuation of the control valve and / or the charging valve at a start of the Internal combustion engine is taken into account. To start the internal combustion engine at a start-stop function, one or more hydraulic motors is connected by appropriate control of the control valve and the charging valve to the pressure accumulator. By the speed sensor device, a starting speed of the internal combustion engine can be determined in a simple manner, so that when exceeding the starting speed and a guarantee of the internal combustion engine by appropriate control of the control valve or charging valve in the blocking position further emptying of the pressure accumulator can be avoided.

With particular advantage, a pressure sensor device for detecting the accumulator charging pressure is provided, which communicates with the electronic control device, wherein the signal of the pressure sensor device upon actuation of the control valve and / or the charging valve when loading the accumulator and / or when starting the internal combustion engine and / or is taken into account in a torque output in the drive train. With the pressure sensor device, the charging process of the pressure accumulator can be monitored in a simple manner and the charging process can be terminated by a corresponding activation of the charging valve in the blocking position at a desired accumulator charging pressure. In addition, depending on the accumulator charging pressure and thus the charge state of the pressure accumulator, the operation of the at least one hydraulic motor can be controlled in the assistance of the internal combustion engine and the duration of the assisting process and thus of the boosting process can be limited.

When using two hydraulic motors as a hydraulic machine, the control valve has a low construction cost if, according to a preferred embodiment of the invention, the input side of a first hydraulic motor is permanently connected to the connecting line and the connection of the second hydraulic motor to the connecting line is controlled by the control valve. which has a blocking position and a flow position. In conjunction with a charging position having a blocking position and a discharge position, in which the connection of the pressure accumulator is shut off with the connecting line or the pressure accumulator is connected to the connecting line, the operation of the first hydraulic motor, which is permanently connected to the connecting line can be controlled. To control the second hydraulic motor, a simply constructed control valve with a blocking position and a flow position can be used.

When using two hydraulic motors as a hydraulic machine controls according to an alternative embodiment of the invention, the control of the connection of the input sides of both hydraulic motors with the connecting line, wherein the control valve has a first control position in which a first hydraulic motor is connected to the connecting line and the connection of the second Hydraulic motor is shut off with the connecting line, and has a second control position, in which both Hydromotors are connected to the connecting line. With such a control valve, which may additionally have a blocking position in which the connection of the connecting line is shut off with the hydraulic motors, it is possible to use a simply constructed storage loading or unloading valve, which is arranged parallel to the connecting line in a Speicherfülleitung.

Particular advantages arise when according to a development of the invention, each hydraulic motor is provided with a circulation device comprising a circulation line connecting the connecting line with a guided from the output side of the hydraulic motor to a container tank line, wherein in the circulation line, a throttle and in Direction to the connecting line opening blocking valve, in particular a check valve, are arranged. When the connection of the input side of the at least one hydraulic motor to the accumulator is established, cavitation occurs on the input side of the hydraulic motor driven by the running internal combustion engine, as a result of which no pressure medium is delivered by the hydraulic motor driven by the internal combustion engine. As a result, low losses can be achieved by the drive of the hydraulic motor while the internal combustion engine is running. About the recirculation formed by a circulation line can be achieved in the locking position befindlichem control valve or charging valve and shut-off connection between the input side of the at least one hydraulic motor and the pressure accumulator, a pressure medium circulation for cooling and lubrication of the driven internal combustion engine hydraulic motor. By appropriate choice of the throttle cross section of the arranged in the circulation throttle a certain minimum circulation quantity can be selected and set so that there are small losses due to the running with internal combustion engine with driven hydraulic motor. The check valve prevents in a simple way that at the start of the engine or in support of the engine pressure fluid from the pressure accumulator can flow to bypass the corresponding hydraulic motor to the container.

The at least one hydraulic motor used as a hydraulic auxiliary drive and / or as a hydraulic starter can be designed as an axial piston machine in swash plate design or oblique-axis design, which can be designed in one or more than several strokes. In addition, the inventive at least one hydraulic motor can be designed as a single-stroke or multi-stroke radial piston machine. Likewise, the at least one hydraulic motor according to the invention can be designed as a vane motor. With regard to a low construction costs and manufacturing costs, special advantages arise when the at least one hydraulic motor is designed as a gear motor, in particular as a gear inner machine or gear outer machine. With one or more gear motors also a small additional space requirement in the axial direction of the drive train can be achieved, so that one or more hydraulic motors of the invention can be installed in a simple manner in the drive train of the internal combustion engine between the primary unit of the drive and the hydraulic pump of the working hydraulic system.

Expediently, different operating strategies are stored in the electronic control device, in which the torque output into the drive train takes place by connecting one or both hydraulic motors as a function of operating parameters, in particular the charge state of the pressure accumulator and the torque request of the internal combustion engine. As a result, optimally adapted torque assistance of the internal combustion engine can be achieved by the hydraulic motors in a simple manner.

Further advantages and details of the invention will be explained in more detail with reference to the embodiments illustrated in the schematic figures. This shows

1 a first embodiment of a drive train according to the invention in a schematic representation,

2 a second embodiment of a drive train according to the invention in a schematic representation and

3 a third embodiment of a drive train according to the invention.

In the 1 is an inventive drive train 1 a mobile work machine, not shown, for example, a truck or a construction or agricultural machine, shown in a schematic diagram.

The drive train according to the invention 1 consists of an internal combustion engine 2 For example, a diesel engine, one of the internal combustion engine 2 driven traction drive 3 as well as one of the internal combustion engine 2 driven working hydraulic system 4 ,

The traction drive 3 is formed in the illustrated embodiment as a hydrostatic drive, which consists of a variable in the delivery volume drive pump 5 As a primary unit, which is to drive with an output shaft 5 of the internal combustion engine 2 is in business connection. The driving pump 5 stands with one or more in the swallow volume fixed or adjustable, not shown hydromotors, in a closed circuit in conjunction, which are in a manner not shown in operative connection with the driven wheels of the machine.

The traction drive 3 Alternatively, as an electric traction drive with one of the internal combustion engine 2 driven electric generator as a primary unit and one or more electric traction motors are formed. In addition, a mechanical traction drive with a mechanical transmission, for example a stepped transmission or a power split transmission or a torque converter transmission can be provided as the drive.

The working hydraulic system 4 Work functions of the working machine, for example, in a truck, a working hydraulics for actuating a lifting device on a lifting mast, or in a construction designed as an excavator construction machine, the working functions of trained by a blade work equipment.

The working hydraulic system 4 includes in the illustrated embodiment at least one operated in the open circuit hydraulic pump 7 that drive to the output shaft 6 of the internal combustion engine 2 is in business connection. The hydraulic pump 7 of the working hydraulic system 4 can be designed as a pump constant in the delivery volume or as adjustable in the delivery pump. The hydraulic pump is preferred 7 of the working hydraulic system 4 designed as adjustable in axial volume piston pump in swash plate design.

The hydraulic pump 7 is on the input side with the suction side by means of a suction line 8th with a container 9 in connection. An output side to the delivery side of the hydraulic pump 7 connected delivery line 10 is to a control valve device 11 connected by means of the non-illustrated hydraulic consumers of the working hydraulic system 4 are controllable. The control valve device 11 preferably comprises one or more directional valves for actuating the consumer. In the illustrated embodiment, furthermore, a priority valve 12 shown with the preferred supply one of the hydraulic pump 7 supplied consumer, for example, a hydraulic steering device can be ensured.

The powertrain 1 further comprises an additional pump designed as a feed pump 13 that drive to the output shaft 6 communicates. The auxiliary pump 13 is designed as fixed displacement pump fixed in the volume, which is operated in the open circuit. The auxiliary pump 13 stands for this with the input side via a suction line with the container 9 in connection and convey in a feed pressure line 14 to which the corresponding consumers of the feed circuit are connected, for example, adjustment devices of the drive pump 5 and the hydraulic pump 7 and a hydrostatic drive input device and pilot valves for the control valves of the work hydraulic system.

The drive train according to the invention 1 further comprises a hydraulic auxiliary drive consisting of a hydraulic pressure accumulator 20 and one with the output shaft 6 of the internal combustion engine 2 operatively connected hydraulic machine 21 consists. As a hydraulic machine 21 is at least one hydraulic motor according to the invention 22a . 22b provided, the input side with a suction side with the hydraulic pressure accumulator 20 is connectable. For this purpose is to the input side of the hydraulic motor 22a . 22b a connection line 23 led to the accumulator 20 is connectable. The hydraulic motor 22a . 22b is the output side with a delivery side with the container 9 in connection. For this purpose is to the output side of the hydraulic motor 22a . 22b one to the container 9 guided container line 24 connected.

The hydraulic motor 22a respectively. 22b is exclusively in a single conveying direction of the pressure accumulator 20 to the container 9 operated and thus exclusively as a motor for driving the output shaft 6 and thus to initiate an additional torque in the drive train 1 and / or as a starter of the internal combustion engine 2 operated.

In the illustrated embodiment, two, each designed as a constant motor hydraulic motors 22a . 22b as a hydraulic machine 21 provided, which are preferably designed as gear machines with a constant displacement volume. The two hydraulic motors 22a . 22b may have the same displacement volume. Preferably, the two hydraulic motors 22a . 22b a different displacement volume, wherein the first hydraulic motor 22a a smaller displacement volume than the second hydraulic motor 22b having.

As in the invention, the hydraulic motors 22a . 22b only in a flow direction and conveying direction of the pressure accumulator 20 to the container 9 operated as a motor, is to charge the pressure accumulator 20 to the required pressure level for the operation of the hydraulic motors 22a . 22b an additional charging device 30 required.

According to the 1 is the charging device 30 from the hydraulic pump 7 of the working hydraulic system 4 formed as a charge pump. For controlling the charging process of the pressure accumulator 20 is a loading valve 31 provided that a loading position 31a in which the delivery line 10 the hydraulic pump 7 with one to the accumulator 20 guided storage line 32 is connectable. The loading valve 31 also has a blocking position 31b on, in which the connection of the delivery line 10 with the storage line 32 is locked.

To drive one or both hydraulic motors 22a . 22b with pressure medium from the accumulator 20 is the loading valve 31 with a discharge position 31c provided in the memory line 32 to the connection line 23 connected. In the locked position 31b as well as the loading position 31a of the loading valve 31 is the connection of the storage line 32 with the connection line 23 shut off.

The loading valve 31 is electrically controlled. Starting from the trained as a middle position blocking position 31b is the charging valve 31 by means of a first actuating device 33a , For example, a solenoid, in the direction of the loading position 31a and by means of a second actuator 33b , For example, a solenoid, in the direction of the Endladestellung 31c actuated. To control are the actuator 33a . 33b with an electronic control device 35 in connection.

In the illustrated embodiment, the first hydraulic motor 22a constantly and directly with the input side to the connection line 23 connected. For controlling the connection of the second hydraulic motor 22b with the connection line 23 is in one to the input side of the second hydraulic motor 22b guided branch of the connecting line 23 an electrically actuated control valve 36 intended. The control valve 36 has a blocking position 36a and a flow position 36b on and is by means of an actuator 37 , For example, a solenoid, between the blocking position 36a and the flow position 36b acted upon. The actuating device 37 is responsible for the control with the electronic control device 35 in connection.

To monitor the accumulator charging pressure and thus the memory state is the accumulator charging pressure of the pressure accumulator 20 detecting pressure sensor device 40 provided with the electronic control device 35 communicates.

Furthermore, for detecting the rotational speed of the internal combustion engine 2 a speed sensor device 41 provided with the electronic control device 35 communicates.

At the hydraulic motors 22a . 22b is in each case a circulation device 50 with a circulation line 51a . 51b intended. The circulation line 51a respectively. 51b is to the connection line 23 between the inlet-side suction port of the corresponding hydraulic motor 22a respectively. 22b and the optional control valve 36 connected and stands with the at the output side delivery port of the hydraulic motor 22a respectively. 22b to a container 9 guided tank line 24 in connection. In the circulation line 51a . 51b is each a throttle 52a . 52b and one towards the connection line 23 opening check valve 53a . 53b , in particular a check valve arranged. With the of the circulation line 51a . 51b formed circulation device 50 can at by the internal combustion engine 2 powered hydraulic motor 22a respectively. 22b and in the locked position 31b located charging valve 31 a low pressure fluid circulation for cooling and lubrication of the running internal combustion engine 2 driven hydraulic motors 22a . 22b Will be provided.

In the in the 1 illustrated powertrain 1 is that of the drive pump 5 formed primary unit of the traction drive 3 directly with the crankshaft of the internal combustion engine 2 connected and directly to the internal combustion engine 2 grown. The hydraulic motors 22a . 22b are between the trained as the primary unit of the traction drive pump 5 and the hydraulic pump 7 of the working hydraulic system 4 in the drive train 1 integrated and on the output shaft 6 arranged.

In the drive train according to the invention 1 the loading of the pressure accumulator takes place during a braking process of the vehicle. When braking the vehicle via the travel drive 3 the drive pump works 5 as a motor, the hydraulic pump 7 of the working hydraulic system 4 drives, so that about in the loading position 31a controlled charging valve 31 the accumulator 20 can be charged with pressure medium. Alternatively or in addition to such recuperation of kinetic energy during a braking operation, the loading of the pressure accumulator 20 also at one of the internal combustion engine 2 driven hydraulic pump 7 take place outside a recuperation period.

With the hydraulic motors 22a . 22b with pressure fluid from the accumulator 20 can be driven, an additional torque in the drive train 1 be initiated for a boost drive. For this purpose, by pressing the charging valve 31 in the unloading position 31c and optionally actuation of the control valve 36 in the locked position 36a that in the accumulator 20 existing pressure medium one of the hydraulic motors or two hydraulic motors 22a . 22b be forwarded to their drive.

Such additional torque becomes during an acceleration phase of the vehicle or during operation of the working hydraulic system 4 to support the internal combustion engine 2 in the drive train 1 initiated. Preferably, such support of the internal combustion engine takes place 2 only by the operation of the first hydraulic motor 22a , which preferably has a smaller displacement volume than the second hydraulic motor 22b has by the charging valve 31 at the beginning of the acceleration process of the vehicle in the unloading position 31c and the control valve 36 in the locked position 36a is controlled. This can be a support of the internal combustion engine 2 be achieved in a boost operation over a longer period. The duration of this boost operation is by means of the pressure sensor device 40 recorded accumulator charging pressure and thus the state of charge of the pressure gauge 20 limited. If at the end of the acceleration process of the vehicle still sufficient pressure medium in the accumulator 20 is present, can in stationary driving at final speed of the hydraulic motor 22a continue to operate and that of the hydraulic motor 22a generated torque can be used while driving.

The hydromotors of the invention 22a . 22b continue to serve as a hydraulic starter of the internal combustion engine 2 in a start-stop function of the internal combustion engine 2 , To start the internal combustion engine 2 is due to the hydraulic pump 7 and the auxiliary pump 13 a high torque to spin the internal combustion engine 2 required. For this purpose, to start the internal combustion engine 2 both hydraulic motors 22a . 22b with pressure medium from the accumulator 20 operated. To start the internal combustion engine 2 becomes the charging valve 31 in the unloading position 31c acted upon, so that the pressure medium from the pressure accumulator 20 and in the flow position 36b located control valve 36 two hydraulic motors 22a . 22b flows in and drives them. With the speed sensor device 41 becomes the speed of the internal combustion engine 2 determined, so that after reaching and exceeding the starting speed, whereby the self-running of the engine is guaranteed, the charging valve 31 in the locked position 31b is pressed to further drain the pressure accumulator 20 to avoid.

In the 2 is an embodiment of 1 illustrated with regard to the execution of the control valve 36 with which the operation of one or both hydraulic motors 22a . 22b can be controlled with pressure medium from the pressure accumulator, of the 1 different.

The control valve 36 of the 2 controls both hydraulic motors 22a . 22b and is for this purpose in the connecting line 23 arranged. The control valve 36 has a first control position 36c on, in which the first hydromotor 22a with the connection line 23 is connected and the connection of the second hydraulic motor 22b with the connection line 23 is locked. In a second control position 36d are both hydraulic motors 22a . 22b with the connection line 23 connected.

The control valve 36 can continue with a trained as a middle position blocking position 36e Be provided in the connection of both hydraulic motors 22a . 22b with the connection line 23 is locked.

The control valve 36 of the 2 is electrically controllable, with actuator 37a . 37b , For example, solenoids, for controlling the control valve in the first control position 36c or the second control position 36d are provided. The controls 37a . 37b are available for control with the electronic control device 35 in connection.

In the 2 becomes the control valve 36 in a boost mode to support the internal combustion engine 2 during an acceleration process of the vehicle or to assist the internal combustion engine 2 during operation of the working hydraulic system in the first control position 36c driven, in which only the first hydraulic motor 22a with pressure medium from the accumulator 20 is driven. To start the internal combustion engine 2 becomes the control valve 36 in the second control position 36d operated to operate by both hydraulic motors 22a . 22b the torque required to spin the internal combustion engine with the coupled hydraulic pumps 5 . 7 and 13 to be able to produce.

The control valve 36 of the 2 can during training of the charging valve 31 with a blocking position 31b without the blocking position 36e be provided and only the first control position 36c for operation of the first hydraulic motor 22a and the second control position 36d for the operation of both hydraulic motors 22a . 22b exhibit.

If the control valve 36 the two hydraulic motors 22a . 22b - like in the 2 is shown - with a blocking position 36e may be attached to the charging valve 31 on the blocking position 31b be dispensed with or the loading valve 31 be formed as a simple valve with a blocking position and a flow position, which is arranged in the storage filling line, which is connected to the connecting line 23 connected.

In the 3 is an embodiment of the 1 and 2 shown in which the two hydraulic motors 22a . 22b - Instead of the coaxial installation and an integration in the drive train 1 on the output shaft 6 between the primary unit of the traction drive 3 and the hydraulic pump 7 of the working hydraulic system 4 - Deaxial on a parallel to the output shaft 6 arranged output shaft 61 are arranged, which have a transmission device 60 with the output shaft 6 is connected.

The transmission device 60 can be formed by a spur gear with a gear stage or a traction mechanism, such as a chain drive.

As in the drive train according to the invention 1 of the 1 to 3 the accumulator 20 only a short operation of the hydraulic motor 7 for starting the internal combustion engine 2 or to support the internal combustion engine 2 during an acceleration process of the vehicle or during operation of the working hydraulic system 4 must allow, is the accumulator 20 preferably formed with a storage volume of less than 100 liters, preferably with a storage volume of 2 to 10 liters, pressure medium. The accumulator 20 is designed for example as a bubble memory. Also other storage types for the accumulator 20 as hydromembrane accumulator or piston accumulator are possible.

The drive train according to the invention 1 made possible with the hydraulic motors 22a . 22b and the accumulator 20 an energy recovery when braking the vehicle and a hydraulic auxiliary drive of the internal combustion engine 2 for the acceleration process in conjunction with a hydraulic starter for a start-stop function of the internal combustion engine 2 ,

The inventive, exclusively in a conveying direction of the pressure accumulator 20 to the container 9 Motor-driven hydraulic motors 22a . 22b are on the output side on the delivery side with the container 9 in connection. Such, exclusively as a motor in a conveying direction of the pressure accumulator 20 to the container 9 operated hydraulic motor 22a respectively. 22b has a low construction cost and manufacturing costs.

By the two designed as constant motors hydraulic motors 22a . 22b , which preferably have different displacer volumes, can by connecting one or both hydraulic motors 22a . 22b by means of the control valve 36 the supporting torque in the drive train 1 to be controlled. This makes it possible, depending on the operating state, the state of charge of the pressure accumulator 20 and the torque request of the internal combustion engine 2 by appropriate control of the control valve 36 an optimally adapted torque support through the operation of one or both hydraulic motors 22a . 22b to achieve. Corresponding operating strategies are in the electronic control device 35 deposited. As constant motors trained hydraulic motors 22a . 22b also have compact dimensions and a small space requirement.

The hydromotors of the invention 22a . 22b that perform the function of a hydraulic starter of the internal combustion engine 2 allow for a start-stop function and the function of a hydraulic auxiliary drive with a recuperated in a braking energy, enable the drive train 1 a mobile work machine, in which with the output shaft 5 of the internal combustion engine 2 a traction drive and at least one hydraulic pump 7 a working hydraulic system 4 are connected, a hydrostatic start-stop function and a hydraulic auxiliary drive with a robust and durable in terms of function at low production costs. The hydraulic auxiliary drive in conjunction with the hydrostatic start-stop function allows for the working machine to reduce fuel consumption in a robust and cost-effective in terms of life. That of the hydraulic motors 22a . 22b in the drive train 1 generated additional torque can be used to downsize the internal combustion engine 2 be used or used to increase the driving performance of the traction drive and / or the Umschlagleitung the work hydraulic system.

The invention is not limited to the illustrated embodiments.

The loading valve 31 and the control valve 36 for controlling the hydraulic motors 22a . 22b can be designed as a switching valve or as throttling in intermediate positions control valves.

Loading the pressure accumulator 20 with pressure medium for energy during a braking operation can also be in a hydrostatic drive with a closed circuit via corresponding valves, such as switching valves, carried out with which the flow for loading the pressure accumulator can be fed out during a braking operation of the closed circuit of the traction drive.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102008028547 A1 [0005]
• DE 3247335 A1 [0006]
• DE 102008021889 A1 [0007]
• WO 2007/071362 A1 [0007]

Claims (27)

Drive train of a vehicle, in particular a mobile work machine, with an internal combustion engine and driven by the internal combustion engine drive and driven by the engine working hydraulic system, the working hydraulic system having at least one driven by the engine hydraulic pump, wherein the drive train with a hydraulic pressure accumulator and one with the Accumulator associated hydromachine for energy recovery and a torque output in the drive train is provided, characterized in that the hydraulic machine ( 21 ) of at least one hydrostatic hydraulic motor ( 22a ; 22b ) is formed, the input side with the hydraulic pressure accumulator ( 20 ) is connectable, on the output side with a container ( 9 ) is in communication and exclusively in a conveying direction of the pressure accumulator ( 20 ) to the container ( 9 ) is operated. Drive train according to claim 1, characterized in that the at least one hydraulic motor ( 22a ; 22b ) as a hydraulic starter for starting the internal combustion engine ( 2 ) is formed at a start-stop function. Drive train according to claim 1 or 2, characterized in that the at least one hydraulic motor ( 22a ; 22b ), the hydraulic pump ( 7 ) of the working hydraulic system ( 4 ) and a primary unit of the traction drive ( 3 ) on an output shaft ( 6 ) of the internal combustion engine ( 2 ) is arranged. Drive train according to claim 1 or 2, characterized in that the at least one hydraulic motor ( 22a ; 22b ) by means of a transmission device ( 60 ) with the output shaft ( 6 ) of the internal combustion engine ( 2 ) in operative connection, on which the primary unit of the traction drive and the hydraulic pump ( 7 ) of the working hydraulic system ( 4 ) are arranged. Drive train according to one of claims 1 to 4, characterized in that a hydraulic pressure accumulator ( 20 ) with pressure medium charging device ( 30 ) is provided. Drive train according to claim 5, characterized in that the hydraulic pump ( 7 ) of the working hydraulic system ( 4 ) as a charging device ( 30 ) for charging the pressure accumulator ( 20 ) is trained. Drive train according to claim 6, characterized in that by means of the hydraulic pump ( 7 ) of the working hydraulic system ( 4 ) charging the accumulator ( 20 ) in braking operation of the traction drive, wherein the hydraulic pump ( 7 ) of the working hydraulic system ( 4 ) of the primary unit of the traction drive operating as a motor ( 3 ) is driven. Drive train according to claim 6 or 7, characterized in that a charging of the pressure accumulator ( 20 ) by a drive of the hydraulic pump ( 7 ) of the working hydraulic system ( 4 ) by the internal combustion engine ( 2 ) he follows. Drive train according to one of claims 1 to 8, characterized in that the hydraulic pump ( 7 ) of the working hydraulic system ( 4 ) is operated in the open circuit and as in the delivery volume adjustable hydraulic pump ( 7 ) or as in the delivery volume constant hydraulic pump ( 7 ) is trained. Drive train according to one of claims 6 to 9, characterized in that an electrically controllable accumulator charging valve ( 31 ), one of which is the 10 ) of the hydraulic pump ( 7 ) of the working hydraulic system ( 4 ) with a to the accumulator ( 20 ) guided storage line ( 32 ) connecting loading position ( 31a ) and one the connection of the delivery line ( 10 ) with the memory line ( 32 ) blocking position ( 31b ; 31c ) having. Drive train according to claim 10, characterized in that the accumulator charging valve ( 31 ) an unloading position ( 31c ), in which the memory line ( 32 ) with a to the input side of the at least one hydraulic motor ( 22a ; 22b ) guided connection line ( 23 ) is connected, wherein in the locked position ( 31b ) of the accumulator charging valve ( 31 ) the connection of the storage line ( 32 ) with the connecting line ( 23 ) is locked. Powertrain after one of the request 1 to 11 , characterized in that at least one adjustment motor adjustable in the displacement volume as a hydraulic machine ( 21 ) is provided. Drive train according to one of Claims 1 to 11, characterized in that at least two constant-velocity motors (constant-speed motors) designed as fixed-displacement constant-speed motors ( 22a . 22b ) as a hydraulic machine ( 21 ) are provided. Drive train according to claim 13, characterized in that the two constant-displacement motors ( 22a . 22b ) have the same displacement volume. Drive train according to claim 13, characterized in that the two constant-displacement motors ( 22a . 22b ) have different displacement volume. Drive train according to one of claims 13 to 15, characterized in that for starting of the internal combustion engine ( 2 ) of the constant displacement motor provided with a larger displacement volume ( 22b ) or both constant motors ( 22a . 22b ) with the accumulator ( 20 ) get connected. Drive train according to one of claims 1 to 16, characterized in that a torque output via the at least one hydraulic motor ( 22a ; 22b ) in the drive train ( 1 ) during an acceleration process of the traction drive and / or operation of the working hydraulic system ( 4 ) he follows. Drive train according to claim 17, characterized in that for a torque output in the drive train, a hydraulic motor ( 22a ), in particular the hydraulic motor with the smaller displacer volume, or both hydraulic motors ( 22a . 22b ) are connected to the accumulator. Drive train according to one of claims 1 to 18, characterized in that for controlling the connection of the input side of the at least one hydraulic motor ( 22a ; 22b ) with the accumulator ( 20 ) in the connection line ( 23 ) an electrically actuable control valve ( 36 ) is arranged. Drive train according to claim 19, characterized in that the charging valve ( 31 ) and the control valve ( 36 ) by means of an electronic control device ( 35 ) is operable. Drive train according to one of claims 2 to 20, characterized in that a rotational speed sensor device ( 41 ) for detecting the rotational speed of the internal combustion engine ( 2 ) provided with the electronic control device ( 35 ), wherein the signal of the rotational speed sensor device upon actuation of the control valve ( 36 ) and / or the charging valve ( 31 ) when starting the internal combustion engine ( 2 ) is taken into account. Drive train according to one of claims 1 to 21, characterized in that a pressure sensor device ( 40 ) is provided for detecting the storage loading pressure, which with the electronic control device ( 35 ), wherein the signal of the pressure sensor device ( 40 ) upon actuation of the control valve ( 36 ) and / or the charging valve ( 31 ) when loading the accumulator ( 20 ) and / or when starting the internal combustion engine ( 2 ) and / or at a torque output in the drive train ( 1 ) is taken into account. Drive train according to one of claims 1 to 22, characterized in that the hydraulic machine ( 21 ) two hydraulic motors ( 22a . 22b ), wherein the input side of a first hydraulic motor ( 22a ) to the connecting line ( 23 ) and the connection of the second hydraulic motor ( 22b ) with the connecting line ( 23 ) by the control valve ( 36 ) is controlled, which is a blocking position ( 36a ) and a flow position ( 36b ) having. Drive train according to one of claims 1 to 22, characterized in that the hydraulic machine ( 21 ) two hydraulic motors ( 22a . 22b ), wherein the control valve ( 36 ) the connection of the input sides of both hydraulic motors ( 22a . 22b ) with the connecting line ( 23 ), wherein the control valve ( 36 ) a first control position ( 36c ), in which a first hydraulic motor ( 22a ) with the connecting line ( 23 ) and the connection of the second hydraulic motor ( 22b ) with the connecting line ( 23 ) is shut off, and a second control position ( 36d ), in which both hydraulic motors ( 22a . 22b ) with the connecting line ( 23 ) are connected. Drive train according to one of claims 1 to 24, characterized in that each hydraulic motor ( 22a . 22b ) with a circulation device ( 50 ), which is a circulation line ( 51a ; 51b ) connecting the connecting line ( 23 ) with one of the output side of the hydraulic motor ( 22a ; 22b ) to a container ( 9 ) guided container line ( 24 ), whereby in the circulation line ( 51a ; 51b ) a throttle ( 52a ; 52b ) and one towards the connecting line ( 23 ) opening check valve ( 53a ; 53b ), in particular a check valve, are arranged. Drive train according to one of claims 1 to 25, characterized in that the hydraulic motor ( 22a ; 22b ) is designed as a gear motor. Drive train according to one of claims 1 to 26, characterized in that in the electronic control device ( 35 ) Operating strategies are laid down in which the torque output in the drive train by connecting one or both hydraulic motors ( 22a ; 22b ) takes place as a function of operating parameters, in particular the state of charge of the pressure accumulator ( 20 ) and the torque request of the internal combustion engine ( 2 ).

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