WO2013092374A1

WO2013092374A1 - Hydrostatic hybrid drive and vehicle having a hydrostatic hybrid drive

Info

Publication number: WO2013092374A1
Application number: PCT/EP2012/075389
Authority: WO
Inventors: Martin Sykora
Original assignee: Robert Bosch Gmbh
Priority date: 2011-12-24
Filing date: 2012-12-13
Publication date: 2013-06-27
Also published as: DE102012001367A1

Abstract

The invention relates to a hydrostatic hybrid drive (18), which has a drive machine (2) and a hydromachine (6, 8) that can be coupled to the drive machine. At least one hydrostatic load (12, 14, 32) can be supplied with a pressure medium by means of the hydromachine (6). Furthermore, the hydrostatic hybrid drive has a control unit (54), which has a signal connection to the drive machine. A pressure medium demand of the hydrostatic load is determined by means of the control unit, and the drive machine can be stopped or started by means of the control unit in accordance with the determined pressure medium demand. The invention further relates to a vehicle having said hydrostatic hybrid drive.

Description

Hydrostatic hybrid drive and vehicle with a hydrostatic hybrid drive

The invention relates to a hydrostatic hybrid drive according to the preamble of patent claim 1 and a vehicle thus according to the preamble of claim 8.

Hydrostatic hybrid drives are used in particular as a driving and / or working drive for mobile construction or agricultural machinery. Furthermore, they are preferably used in trucks or in public transport vehicles. They have an engine, in particular a combustion or diesel engine, with which at least one hydrostatic machine is coupled. The coupling takes place via a drive shaft of the drive machine. For example, a wheel or an axle unit of the vehicle is driven via the hydrostatic machine. Furthermore, an implement of the vehicle, for example a lifting or slewing gear or a fan or an air conditioning system with pressure medium and thus with drive energy can be supplied via this hydrostatic machine or another coupled to the drive machine hydrostatic machine. With the help of the prime mover or the internal combustion engine, the driveand various working functions and the above-described working units of the vehicle are supplied with hydrostatic pressure medium energy as drive energy in this way.

Against the background of stricter exhaust emission limits and a reduction of CO2 emissions, the task is to increase the energy efficiency of the drive. One solution to this problem is the use of drives with hydropneumatic energy storage devices, which enable regenerative braking, for example. Such a solution describes the published patent application DE 10 2006 010 508 A1. Therein a hydrostatic hybrid drive is described which has a drive motor, in particular a diesel engine, which is coupled via a shaft with two hydraulic machines. It can be on the shaft a drive torque for an axle or Wheel unit can be tapped and on the first hydraulic machine, a hydro-pneumatic accumulator and a second hydraulic machine of a hydrostatic

Working cycle are supplied with pressure medium. In normal operation, the axle unit is driven by the combustion engine via the shaft. In braking mode, a braking torque is generated by the first hydraulic machine runs in pump mode and promotes pressure medium in the hydropneumatic accumulator. In this way, braking energy, which would normally have been lost, held in the form of pressure medium energy in the hydropneumatic accumulator. For the following starting operations or for use in the working cycle, the recovery of the pressure medium energy can take place.

Compared to this solution, the energy efficiency of the drive still appears

in need of improvement.

The invention is therefore based on the object to provide a hydrostatic hybrid drive with a higher energy efficiency. Furthermore, the invention has the object to provide a vehicle with a higher energy efficiency.

This object is achieved by a hydrostatic hybrid drive with the

Features of claim 1 and by a vehicle having the features of claim 8.

Advantageous developments of the hydrostatic hybrid drive are in the

Claims 2 to 7 described, advantageous developments of the vehicle are described in claim 9.

A hydrostatic hybrid drive, in particular a mobile construction or agricultural machine or a truck or a vehicle of the local public transport or a municipal vehicle, for example a sweeper or a multi-device carrier, has a prime mover, which is designed in particular as a combustion or diesel engine or as an electric motor. Furthermore, the hybrid drive has a first coupled in particular via a shaft to the drive machine Hydromachine on. About this at least one hydrostatic consumer can be supplied with pressure medium. Furthermore, the hybrid drive has a control unit

(Vehicle control unit), with the prime mover, in particular with their

Control unit, and with the hydrostatic load, in particular with a

Sensor unit of the hydrostatic load and optionally (all) further energy-relevant and system-relevant vehicle systems (for example, brake system, air conditioning), is in signal communication. In this case, a pressure medium requirement of the at least one hydrostatic consumer can be determined via the control unit.

It is also possible to determine whether a running engine is required for any further consumer. According to the invention the drive machine on the

Control unit depending on the determined pressure medium requirement and the general vehicle requirements automatically stopped or deactivated. The stopping takes place according to the invention when it is determined via the control unit that the at least one hydrostatic consumer has no pressure medium requirement

or no system-relevant vehicle function needs to be supplied with power. It is advantageous if the regenerative hybrid system at

Shutdown has stored energy so that then the diesel engine can also be restarted via the hybrid system.

Compared to conventional hydrostatic hybrid drives, as disclosed for example in the prior art according to DE 10 2006 010 508 A1, the hybrid drive according to the invention thus an automatic stop of the prime mover or the internal combustion engine, resulting in an "unnecessary" idling the engine during operating hours of Hybrid drive in which the

hydrostatic or the hydrostatic consumer no pressure medium needed or no system-relevant functions are required prevented. The "unnecessary" idle times are approximately 20 to 50% of the operating time, in particular for construction machines, and account for approximately 10% of the energy consumption of the work machine

or energy yield compared to the hybrid drives of the prior art, since it prevents this unnecessary idling operation. In an advantageous development of the invention, the hydrostatic hybrid drive has an operator interface, which is in signal communication with the control unit and can be detected via the at least one operating request of an operator. In this case, the drive machine can be automatically stopped via the control unit in dependence on the at least one operating request. In addition to the automated stopping of the prime mover in the absence of pressure medium demand thus an automated stopping of the prime mover is made possible in a lack of operating requirement. Possible operating requirements are, for example, an acceleration, lifting, lowering or turning of a load by the hydrostatic consumer or a generation of a drive torque by the drive machine. With this development of the invention, the hydrostatic hybrid drive is further improved in terms of its energy efficiency.

Alternatively or additionally, a development of the invention has a detection unit in signal communication with the control unit, via which a

Presence of an operator is detectable. In this case, the drive machine via the control unit in response to the presence or absence of the operator is automatically stopped. The detection unit may be, for example, a motion detector or a light barrier. This development of the hydrostatic hybrid drive results in a further improvement in energy efficiency, since the prime mover is not automatically idle in the absence of the operator and consumes energy.

In a particularly preferred and advantageous refinement, the energy efficiency of the hydrostatic hybrid drive is further improved in that the hybrid drive has a hydropneumatic accumulator which can be brought into fluid communication via in each case at least one working line with the first hydraulic machine and with the hydrostatic load or consumers. The working lines and the hydropneumatic accumulator are connected to a valve unit, which is in signal communication with the control unit. Also, the hydrostatic accumulator is preferably connected via a working line to the valve unit. If, for example, the hydrostatic load is in an operating state in which it is working or printing emits medium energy, the valve unit can be switched via the control unit such that the pressure medium is conveyed directly into the memory. For example, can be done in this way when lowering a load of the hydrostatic load storage of the potential energy of the load in the form of pressure medium energy. In a preferred development, the hydrostatic hybrid drive has a second hydraulic machine, which is coupled to the first hydraulic machine, and via which one or more further hydrostatic consumers can be supplied with pressure medium. If now the hydrostatic consumer supplied via the second hydraulic machine is in an operating state in which it gives off work, it drives the second hydraulic machine. This is in engine operation from a drive torque to the first hydraulic machine, which thereby promotes pressure medium in the hydropneumatic accumulator. An example of this is the storage of kinetic energy or braking energy of the hydrostatic hybrid drive in the form of hydraulic pressure energy in the hydropneumatic accumulator. The hydrostatic hybrid drive according to the invention is suitable in both developments for hydrostatic regenerative braking. The pressure medium energy stored in the hydropneumatic accumulator can be made available to the hydrostatic load via a corresponding switching position of the valve unit either directly or indirectly via the first and second hydraulic machines.

In a particularly preferred embodiment of the invention, the first or second hydraulic machine is adjustable, in particular durchschwenkbar formed. Alternatively, the first or second hydraulic machine may be formed as a constant machine.

A particularly advantageous and convenient operation of the hydrostatic hybrid drive is obtained in a development in which the control unit is configured such that the prime mover via them depending on the determined pressure medium requirement and / or the detected operating requirement and / or the detected presence of the operator and / or Automatically startable from the demand for system-relevant functions. This results in a start-stop system depending on the operating conditions or operating conditions of the hydrostatic hybrid drive. Preferably, the signal connection or the signal connections via a field bus, in particular a CAN bus, designed. Such a serial signal connection has a lower cabling complexity compared to conventionally parallel signal connections. Alternatively, but also discrete

Signal transmissions, for example by analog voltage signal, or others are used.

An inventive vehicle, in particular a mobile construction machine or mobile agricultural machine or a public transport vehicle, such as a passenger bus or a municipal vehicle, has a hydrostatic hybrid drive according to the foregoing description. In this case, the at least one hydrostatic consumer is coupled to a working device of the vehicle, in particular to a lifting or slewing gear, or to a wheel or axle unit or to a fan or to an air conditioning system of the vehicle and drives it. The vehicle is particularly energy-efficient due to the above-described automatic stop of the prime mover depending on the pressure medium requirement. The energy efficiency of the vehicle is increased analogously to the previous description of the

Hybrid drive with the respective developments of the invention

Hybrid drive.

In the following, an embodiment of a hydrostatic hybrid drive according to the invention will be explained in more detail with reference to a drawing.

A hydrostatic hybrid drive 1 has a drive machine 2, which is coupled to a second hydraulic machine 8 via a shaft 4a with a first hydraulic machine 6 and via shafts 4b and 4c. The engine 2 is further coupled via the shafts 4a and 4b to a hydraulic pump 10. The hydrostatic hybrid drive 1 according to FIG. 1 is installed, for example, in an agricultural tractor or in a municipal vehicle. The hydrostatic hybrid drive further comprises two hydrostatic loads 12 and 14, wherein the hydrostatic load 12 as a single-acting hydraulic cylinder and the hydrostatic load 14 as double-acting hydraulic cylinder is designed. About the hydrostatic

Consumers 12, 14, not shown hoists of the tractor are articulated.

Via a first and a second working line 18, 20, the hydraulic machine 8 is connected to the hydraulic machine 16. The two hydraulic machines 8, 16 operate in a closed circuit, wherein according to Figure 1 tank lines 22a, 22b, which are connectable to a tank T, are indicated. The hydraulic machine 16 is connected via a shaft 5 with a gear 44 of an axle unit 46 of the agricultural machine. The

Axis unit 46 has two wheels 47.

Furthermore, the hydrostatic hybrid drive 1 according to FIG. 1 has a hydropneumatic accumulator 24 which can be connected to the first hydraulic machine 6 via a working line 26, a switching position, not shown, of a valve unit 28 and a working line 30. As a further hydrostatic consumer 32, the hydrostatic hybrid drive 1 on a fan of the drive machine 2. The prime mover 2 is designed as a diesel engine. The hydrostatic consumer 32 or the fan is connected via not shown switching positions of the valve unit 28 either via a working line 34 with the hydropneumatic accumulator 24 or via the working line 26 with the first hydraulic machine 6. He is thus supplied either via the prime mover 2 and the hydraulic machine 6 or via the hydropneumatic accumulator 24 with pressure medium.

The two hydrostatic consumers 12 and 14 are connected via two working lines 36 and 38 with a valve unit 40 and can each be connected via a not shown switching position of the valve unit 40 and a working line 42 with the valve unit 28. As indicated, the working line 42 can also be connected to a tank. The connection to the tank is shut off by a valve, not shown, when memory 24 and consumer 12 or 14 are connected to each other. Not shown switching positions of the valve unit 28, the hydrostatic consumers 12, 14 further connected either with the hydropneumatic accumulator 24 or with the hydraulic machine 6. Thus, these hydrostatic consumers 12, 14 either via the prime mover 2 and the Hydromachine 6 or supplied via the hydropneumatic accumulator 24 with pressure medium. The valve units 28 and 40 have further working lines 48 and 50, which are indicated in accordance with FIG. Additional hydrostatic loads, aggregates or accumulators can be connected to these two working lines. The valve 40 may be fluidly connected in a manner not shown via a pump line to the hydraulic machine 10.

For a control of the hydrostatic drive 1, this has an operator interface 52 and a control unit 54. The operator interface 52 comprises control elements, not shown, for actuating the hydrostatic loads 12, 14 or the hoists, as well as an operating element for controlling the drive machine 2 by the operator, in particular Acceleration of the agricultural machine, as well as an operating element for controlling an air conditioner of the agricultural machine, not shown. To control the engine 2, the hydrostatic hybrid drive 1 has a diesel control unit 56.

In order to enable control of the engine 2 as a function of the pressure medium requirement, an operating requirement by the operator or his presence or absence, or to determine whether system-relevant functions are required, the hydrostatic hybrid drive 1 according to Figure 1 has a plurality of determination and detection units , via which an operating state of the hydrostatic consumers 12, 14, 32, the valve units 28, 40, the hydropneumatic accumulator 24, the engine 2, and the hydraulic machine 6, 8, 16, the hydraulic pump 10 and the axle unit 46 detectable or determinable This means that all system-relevant signals required for the start-stop decision are recorded and evaluated. A pressure determination unit 58 connected to the working line 30, via which a storage pressure of the hydropneumatic accumulator 24 can be determined, one (or several actuators on the valve) actuator 60 or 62 of the valve units 28 or 40, via which a respective switching position of the corresponding valve unit 28, 40 determinable and controllable, a displacement sensor 60 and 66 of the hydraulic cylinder or hydrostatic consumers 12, 14, via which the position of the piston in the Hydraulic cylinder 12, 14 is determinnnable, a temperature determining unit 68 via which an oil or cooling water temperature of the prime mover 2 is determinable, a Drehzahlbestinnnnungseinheit 70, via which a rotational speed of the Achseinheit 46 is determinable, and finally a detection unit 72, via which an operator of the hydrostatic Hybrid drive 1 or the agricultural machine detectable, that is detectable, is.

The aforementioned detection or determination units are connected to the control unit 54 via a serial CAN bus 74 or via a discrete signal line (for example analog signal). According to FIG. 1, the CAN bus 74 or the signal line is shown as a dashed signal line for each of the determination or detection units. If the signal line is discrete, multiple lines may be required. Not only a determination or detection of a corresponding size of the respective determination or detection unit can take place via the CAN bus 74, but under certain circumstances also a control of an associated control element (for example, in the case of valves with on-board electronics). As a rule, however, this is done via a discrete activation, ie by means of a current or voltage signal to the consumer. This relates in particular to the adjustably designed hydraulic machines 6, 8, 16, and the adjustable hydraulic pump 10 and the designed with a Versteilmotor hydrostatic load 32 of the fan, as well as the two valve units 28 and 40. This direction of action of the control unit 54 to said control elements or actuator units represented by a directed to the actuators arrow of the CAN bus representing dashed lines.

In the control unit 54 according to the invention thus run the operating state of the hydrostatic hybrid drive 1 defining state variables such as the pressure in the hydropneumatic accumulator 24, the temperature of the engine 2, the

Speed of the axle unit 46, the position of the piston of the hydrostatic load 12 and 14, and the valve switching positions of the valve units 28 and 40 so all necessary for the start-stop decision system-relevant signals together. In addition, the control unit 54 receives information about Whether the operator of the agricultural machine or the hydrostatic hybrid drive 1 is present. This is done via the detection unit 72. As further information, the aforementioned settings or setpoint values of the user interface 52 enter into the control unit 54 via a signal connection 53.

According to the invention, the control unit 54 is configured in such a way that the setpoint values set via the operator interface 52 and the other named measured variables of the determination or detection units are evaluated by the control unit 54 and a pressure medium requirement, for example for a drive of the axle unit 46 or for a hydrostatic pressure medium supply Consumers 12, 14, 32 or the hydropneumatic accumulator 24 is determined. If the control unit 54 determines that no pressure medium requirement exists and that no further system-relevant element has to be supplied with drive energy from the drive machine, a signal is sent from the control unit 54 to the control unit 56 of the drive machine 2 to switch it off or to stop it. This is done by a CAN message to interrupt the injection (motor = stop). In this way, the prime mover 2 or the diesel engine runs only when one of the hydrostatic loads 12, 14, 32 or the traction drive or the axle unit 46 requires pressure medium, a systemically important element must be supplied with energy or the hydropneumatic accumulator 24 are charged with pressure medium should.

The control unit 54 according to the invention is now further configured such that the shutdown of the drive machine 2 also takes place in dependence on a presence or the absence of the operator. However, the prerequisite for this is that the control unit 54 could determine beforehand that no pressure medium is required. Via the operator interface 52, the control unit 54 can be configured such that the detection of the operator enters into the automated shutdown of the prime mover 2 or not.

In the illustrated embodiment, the control unit 54 is further configured such that it turns off the prime mover 2 even when within a predetermined, configurable period of time, no operator operation request is made to the operator interface 52. In this context, it is still important that, based on the set nominal values of the operator interface 52, via which this start-stop function can also be deactivated, and the values reported by the determination or detection units, by the control unit 54 for the hydrostatic Consumers 12, 14, 32 or the axle unit 46 or the hydropneumatic accumulator 24 no pressure medium requirement is determined and no systemically important element must be supplied with energy. Only when this condition is met, the shutdown of the prime mover 2 takes place.

The above-described automated shutdowns of the engine 2 in the absence of pressure medium requirement, lack of operating requirements of the operator when no systemically important element must be supplied with energy, or detected absence of the operator reduce the operating times in which the hydrostatic hybrid drive 1 is operated at idle. In this way, an automatic stop of the hybrid drive 1 is realized and increases its energy efficiency. Essentially, the idling and thus "unnecessary" consumption of gasoline or diesel is avoided by the shutdown of the engine, which leads accordingly to increase the energy efficiency of the entire machine.

In order to further increase the energy efficiency of the hydrostatic hybrid drive 1, braking energy or unnecessary potential or kinetic energy of the loads moved by the hydrostatic loads 12, 14, 32 can be stored in the hydro-pneumatic accumulator 24. For example, it is possible to brake the axle unit 46 requested via the user interface 52 instead of using conventional brakes (not shown) of the axle unit 46 via a sliding operation of the hydraulic machine 16. Depending on the direction of travel of the hybrid drive 1 or the agricultural machine is thereby operated via the working line 18 and 20, the hydraulic machine 8 as a hydraulic motor. The hydraulic machine 8 delivers a drive torque to the hydraulic machine 6 via the shafts 4c and 4b, whereby the hydraulic machine 6 fills the hydropneumatic accumulator 24 via the working lines 26 and 30 with pressure medium. In this case, the valve unit 28 is controlled via the control unit 54 in such a way, that the two working lines 26 and 30 are connected. An analogous filling of the hydropneumatic accumulator 24 can take place via the working lines 36 or 38 and 42 and 30 by, for example, braking or lowering a load of the hydrostatic loads 12, 14. Conversely, the pressure medium energy stored in the hydropneumatic accumulator 24 of the axle unit 46 or the hydrostatic consumers 12, 14, 32 can be provided via a valve switching position of the valve units 28 and 40, respectively. This provision is controlled via the control unit 54 and the CAN bus 74 or by a discrete control signal (for example, current at the valve magnet).

The control unit 54 according to the invention is designed such that in addition to the above-described automatic stop and an automatic start the drive machine 2 in response to the pressure medium requirement, when energy demand system-relevant elements or the operation request by the operator or the renewed presence of the operator. Two variants are conceivable on the one hand: On the one hand, the control unit 54 can cause the starting machine 2 to be started via an unillustrated electric starter motor when the pressure medium requirement, energy demand of system-relevant elements or detected operating requirement or presence of the operator is reached. However, this alternative has the disadvantage that the starter motor is subject to wear. Therefore, this alternative is particularly preferred in pressureless hydropneumatic reservoir 24. Alternatively or additionally, the control unit 54 may start the engine 2 via the hydraulic machine 6 by utilizing the pressure medium energy stored in the hydropneumatic accumulator 24. In this case, a control signal is sent to the actuator 60 of the valve unit 28 by the control unit 54 via the CAN bus 74 or by means of a discrete signal (for example, current on the valve magnet), so that the working lines 30 and 26 are connected and a working connection of the hydraulic machine 6 is acted upon with pressure medium. As a result, the hydraulic machine 6 drives the shaft 4a to start the engine 2 (without using the electric starter motor). The

Hydromaschine 6 is designed durchschwenkbar. The control unit 54 is designed monitoring, that is, it continuously adjusts the reported via the CAN bus 74 or alternative fieldbus systems to the control unit 54 state information of determination or detection units of the hydrostatic hybrid drive 1 with the set via the user interface 52 setpoints and determines the pressure medium demand or checks via various sensor units, whether system-relevant element must be supplied with energy.

Disclosed is a hydrostatic hybrid drive having a drive machine and a coupled with this hydraulic machine. At least one hydrostatic consumer can be supplied with pressure medium via the hydraulic machine. Furthermore, the hydrostatic hybrid drive has a control unit which is in signal communication with the drive machine. In this case, a pressure medium requirement of the hydrostatic load is determined via the control unit. Here is the prime mover on the

Control unit automatically stopable depending on the determined pressure medium requirement.

Disclosed is still a vehicle with this hydrostatic hybrid drive.

Claims

claims

1 . Hydrostatic hybrid drive with a drive machine (2) and with a to the drive machine (2) coupled to the first hydraulic machine (6, 8) via which at least one hydrostatic load (12, 14, 32, 16) can be supplied with pressure medium, and with a control unit (54) which is in signal communication with the drive machine (2), wherein via the control unit (54) a pressure medium requirement of the at least one hydrostatic load (12, 14, 32, 16) can be determined, characterized in that the drive machine (2) via the control unit (54) as a function of

Pressure medium requirement is automatically stoppable

2. Hydrostatic hybrid drive according to claim 1, with an operator interface (52) which is in signal communication with the control unit (54), and on the at least one operating request of an operator can be detected, wherein the drive machine (2) via the control unit (54 ) depending on the at least one

Operational request is automatically stoppable.

3. Hydrostatic hybrid drive according to claim 1 or 2, with a

Detection unit (72) which is in signal communication with the control unit, and via which a presence of an operator can be detected, wherein the drive machine (2) via the control unit (54) is automatically stopped in response to the presence.

4. Hydrostatic hybrid drive according to one of the preceding claims, comprising a hydropneumatic accumulator (24), each having at least one

Working line (26, 42, 34) with the first hydraulic machine (6) and with the at least one hydrostatic load (12, 14, 32) can be brought into fluid communication, wherein the hydropneumatic accumulator (24) and the working line (26, 42, 34 ) are connected to a valve unit (28) connected to the control unit (54) in

Signal connection is.

5. Hydrostatic hybrid drive according to one of the preceding claims, wherein the hydraulic machine (6, 8, 16) is adjustable.

6. Hydrostatic hybrid drive according to one of the preceding claims, wherein the drive machine (2) via the control unit (54) in dependence of the determined pressure medium requirement or the detected operating requirement or the detected presence is automatically bootable.

7. Hydrostatic hybrid drive according to one of the preceding claims, wherein the signal connection or signal connections via a field bus (74) is configured or are.

8. The vehicle with a hydrostatic hybrid drive according to one of the claims 1 to 7, wherein the at least one hydrostatic load (12, 14, 32, 16) with a working device or with a wheel or axle unit (46) or with a fan or with a Air conditioning or other system-related elements is coupled.

9. Vehicle according to claim 8, wherein the hydrostatic load (12, 14, 32, 16) is a hydraulic machine (16) or a hydraulic motor (32) or a hydraulic cylinder (12, 14).