阅读说明：本技术 电液的驱动单元和具有该驱动单元的可移动的做功机械 (Electrohydraulic drive unit and mobile work machine having the drive unit ) 是由 P.纳格尔 N.施特克 S.罗泽 于 2019-06-27 设计创作，主要内容包括：本发明涉及一种用于特别是可移动的做功机械的电液的驱动单元,具有构造成电机的、有驱动功率的驱动机和能由该驱动机驱动的机械的输出装置,以及具有液压机和能由该液压机驱动的液压的输出装置。本发明还涉及一种具有该驱动单元的可移动的做功机械。(The invention relates to an electrohydraulic drive unit for a, in particular, mobile work machine, having a drive machine, which is designed as an electric motor, having a drive output and having a machine output which can be driven by the drive machine, and having a hydraulic machine and having a hydraulic output which can be driven by the hydraulic machine. The invention also relates to a movable work machine having such a drive unit.)

1. Electrohydraulic drive unit for a particularly mobile work machine, having a drive power (P) designed as an electric motor (2)₄) And a mechanical output device (12) which can be driven by the drive machine, and a hydraulic machine (6; 6. 106) and a hydraulic output device (16, 18; 16. 18, 116, 118) characterized by a drive power (P)₄) Can be divided.

2. Drive unit according to claim 1, wherein the drive power (P)₄) Is selectively shuntable to the hydraulic output (16, 18; 16. 18, 116, 118) or on the output device (12) of the machine.

3. Drive unit according to claim 1 or 2, wherein the drive power (P)₄) Can be divided in portions into the hydraulic outputs (16, 18; 16. 18, 116, 118) and on the output device (12) of the machine.

4. The drive unit according to any one of claims 1 to 3, wherein the drive power (P)₄) Is variably branched to the hydraulic output (16, 18; 16. 18, 116, 118) and on the output device (12) of the machine.

5. The drive unit according to one of the preceding claims, having an actuatable clutch (10) between the electric machine (2) and the mechanical output (12).

6. Drive unit according to any of the preceding claims, wherein the drive power (P)₄) Can be divided on the hydraulic machine (6).

7. Drive unit according to one of the preceding claims, wherein a drive shaft (4, 8) of the hydraulic machine (6) is connected non-rotatably and fixedly or non-rotatably and detachably with the electric motor (2) and the mechanical output (12).

8. Drive unit according to any one of the preceding claims, wherein the hydraulic machine (6) has an adjustable squeeze volume (V)₆) And a fixed clutch is arranged between the motor (2) and the hydraulic machine (6).

9. The drive unit according to any one of claims 1 to 7, wherein the hydraulic machine has a constant pressing volume and an actuatable clutch is provided between the electric machine and the hydraulic machine.

10. Drive unit according to one of the preceding claims, wherein the electric machine (6; 106) is drivable in generator operation for the recovery of energy of at least one of the output devices (12, 16, 18; 12, 16, 18, 116, 118).

11. The drive unit according to any one of the preceding claims, wherein the power of the output devices (12, 16, 18; 12, 16, 18, 116, 118) can be added on the hydraulic machine (6).

12. Drive unit according to one of the preceding claims, having an electrical and/or hydraulic storage unit to store recovered energy of at least one of the output devices (12, 16, 18; 12, 16, 18, 116, 118).

13. The drive unit according to one of the preceding claims, having a second drive machine (102), in particular a second electric motor, having a second drive power and a second hydraulic machine (106) which can be driven by the second drive machine and a second hydraulic output (116, 118) which can be driven by the second hydraulic machine, and having a valve arrangement (48) by means of which the pressure medium volume flows of the hydraulic machines (6; 6, 106) can be added.

14. Mobile work machine having an electrohydraulic drive unit (1; 101) which is designed according to at least one of the preceding claims.

15. The work machine according to claim 14, wherein the machine output device (12) is a rotary mechanism, in particular a rotary mechanism of a structural component of the work machine.

Technical Field

The present invention relates to an electrohydraulic drive unit for a movable work machine according to the preamble of claim 1 and to a movable work machine having such a drive unit according to claim 14.

Background

From the prior art, a mobile work machine is known, which has an actuator for controlling a boom, a handle or a bucket, for example. Furthermore, rotary drives, such as slewing gear motors, traction motors or fan motors, are often provided. Such a work machine is, for example, an excavator. The actuator or output device is typically implemented hydraulically. Compact excavators or mobile excavators with weight classes between 8 and 17 tons have, for example, systems with hydraulic pumps to which the output is connected by means of valves that can be integrated in a hydraulic control block. The hydraulic pump is driven by a drive machine designed as an internal combustion engine. The traction motor is supplied with pressure medium by the same hydraulic machine via a valve control mechanism.

In order to be able to reduce energy losses by selectively switching off individual hydraulic pumps or couplings, in larger work machines, for example from a loading weight of 20 tons, a plurality of hydraulic pumps are provided for supplying pressure medium to the actuators or the output devices. In this case, for example, the volumetric flows of the pressure medium of the two hydraulic pumps can be added so that they behave like a single large hydraulic machine. On the other hand, when the volume flow of the pressure medium is low, the efficiency of the remaining hydraulic pump can be improved by coupling the two hydraulic circuits with one of the hydraulic pumps switched off.

In the context of increasing demands on the non-or low-emission drive systems of mobile work machines, electrification of the drive systems has begun. Thus, for example, Komatsu from its hybrid model HB215LC-2 shows an excavator with a slewing gear output which is purely electrically driven. In addition to reducing emissions by means of electrified drives, such excavators also allow energy recovery by storing kinetic energy, for example of a slewing gear, in the electrical domain, in particular in high-power capacitors. In the hybrid type, the stored electric energy is used supportively at high acceleration of the internal combustion engine (diesel engine). The disclosed drive system thus helps to save fuel and reduce emissions.

A disadvantage of this solution is that the more expensive and costly electric drive technology can be used only for one of the outputs and is idle during the rest time of the output.

Disclosure of Invention

The object of the present invention is to provide an electrohydraulic drive unit for a mobile work machine, which drive unit has a higher load level. Another object is to create a mobile work machine with an electrohydraulic drive unit which is more highly loaded.

The first task is solved by an electrohydraulic drive unit having the features of claim 1, and the second task is solved by a movable working machine having the features of claim 14.

Advantageous developments of the electrohydraulic drive unit are specified in claims 2 to 13. An advantageous development of the mobile work machine is specified in claim 15.

An electrohydraulic drive unit for a work machine, in particular a mobile work machine, in particular an excavator, has a drive machine in the form of an electric motor. The drive power of the drive machine is used to drive the mechanical output of the drive unit. The mechanical output device is in particular rotary, in particular a slewing gear. The drive unit also has a hydraulic machine for the supply of hydraulic medium and thus for hydraulically driving the hydraulic output of the drive unit. According to the invention, the drive power of the electric motor is dividable and can therefore be used not only to drive the mechanical output device but also to drive one or more further output devices.

By means of the shunt, the electric machine does not have to be stopped in a forced manner during the standstill time of the mechanical output, but can be used for other purposes. This increases or at least increases its load level and the load level of the drive unit, so that the investment costs can be reduced. The drive power provided by the partial flow can thus result, for example, in the elimination of an otherwise necessary drive machine at other points of the drive unit or in the possibility of designing this drive machine at least smaller.

In a further development, the partial flows can be controlled in particular by a control unit of the drive unit in such a way that the drive power is supplied selectively either to the hydraulic machine or to the output of the machine. The drive power then only provides the output for driving the hydraulic pressure during the stationary phase of the mechanical output, but also overall.

In a further development, the partial flows can alternatively or additionally be controlled in such a way that the drive power can be divided in portions to the hydraulic machine and to the mechanical output. This way or control of the shunting has proved to be more flexible and to improve the load level (Auslastung) compared to the described improved solutions with only selective shunting.

The fraction may be fixed, varied in stages or varied continuously. The alternatives may be provided as alternatives or supplements to each other.

In order to achieve a shunt and/or to interrupt the power path between the electric machine and the output of the machine or at least to reduce the drive power transmitted to said power path, in a development an actuatable clutch is arranged between the electric machine and the output of the machine.

The clutch can be designed such that it can be actuated under no load or under load. The clutch may be a friction clutch, a wet-running or dry-running plate clutch, a torque converter or a form-fitting clutch. Depending on the design, the power path can then be selectively either connected or interrupted, or the drive power delivered can be varied, as in a slip clutch or a torque converter.

In one refinement, the drive unit has a brake for braking and/or arresting the output of the machine.

A development in which the drive power can be split over the hydraulic machine has proven particularly compact. The hydraulic machine thus functions both as a hydraulic drive for the hydraulic output and as a power divider or power divider, so that, for example, the mechanical gear mechanism for power division can be omitted.

For the purpose of power splitting on the hydraulic machine, in a development the drive shaft or through drive (durchrieb) of the hydraulic machine can be connected on the one hand to the electric motor and on the other hand to the output of the machine.

If the hydraulic machine has a displacement volume which can be set, in particular, to zero in a development, the power split can only be carried out if the hydraulic machine is fixedly connected to the electric machine, i.e. if a releasable, but fixed clutch is not provided here. The partial flows can then be effected in portions by stepwise or continuous adjustment of the press volume.

In one variant, the hydraulic machine has a constant displacement volume. An actuatable clutch is then provided between the electric machine and the hydraulic machine, by means of which clutch a power path between the electric machine and the hydraulic machine can be formed and interrupted.

The drive unit is designed more energy-efficient if the electric machine is designed in a development such that hydraulic energy and/or kinetic energy of at least one of the outputs can be recovered by the electric machine, i.e. the electric machine can be driven during operation of the generator.

For this purpose, the power of the output device is preferably added to the drive shaft of the hydraulic machine. The through drive of the hydraulic machine, which is connected to the mechanical output, is an input for the power to be recovered of the mechanical output, for example, and the high-pressure connection or working connection of the hydraulic machine, which is connected to the hydraulic output, is an input for the power to be recovered of the hydraulic output.

In addition to the possibility of converting the recovered power of the respective output by means of the hydraulic machine and directing it directly to the other outputs in the output, a first supplementary or alternative development has emerged in which the energy can be supplied to the electrical storage unit, in particular a high-power capacitor, of the drive unit via an electric machine operating in generator mode. In a second additional or alternative refinement, the energy can be supplied to a hydraulic storage unit, in particular a hydraulic storage unit, of the drive unit by means of the hydraulic machine and stored therein.

In one refinement, the drive unit has a control unit, by means of which the diversion, addition, actuation of the clutch and/or the recovery can be controlled as a function of a request at least one of the outputs and/or an operating state of the drive unit or of the movable work machine.

A further, more flexibly usable development of the drive unit has a second drive machine, in particular a second electric machine, having a second drive output and a second hydraulic press which can be driven by the second drive machine and a second hydraulic output which can be driven by the second hydraulic press. In this way, two separate or separable hydraulic circuits can be set up.

In one development, the working connections of the two hydraulic machines can be connected by means of an additional valve arrangement. The pressure medium volume flow of the hydraulic machine and thus the hydraulic power can therefore be fed into one of the circuits and can be added.

In the opposite case of recovery, the valve arrangement in one development can add the pressure medium volume flows of the circuits and for example feed only one of the hydraulic machines, which then runs in motor mode.

With the first-mentioned hydraulic machine, on which the drive power can be split as described above and the output powers can be added in a complementary manner, the power of all the outputs or of a subset thereof can then be added to only one of the electric machines in cooperation with the valve device.

In one refinement, the drive unit and in particular the hydraulic output are designed such that the hydraulic output can be operated in the opposite direction.

The movable work machine has a drive unit which is designed according to at least one aspect of the preceding description. The machine output device is preferably a rotary mechanism, in particular a rotary mechanism of a component (Aufbau) of a work machine. The advantages of a movable work machine result from the advantages described for the drive unit. By using the electric motor more flexibly (not only for driving the output of the machine), the otherwise required drive machine can optionally be dispensed with at other points of the work machine, as a result of which the installation space, weight and costs can be saved.

Drawings

Two exemplary embodiments of an electrohydraulic drive unit according to the invention are shown in the figures. The invention will now be explained in detail with the aid of said figures. In the figure:

fig. 1 shows a first exemplary embodiment of an electrohydraulic drive unit according to the invention for a movable work machine;

fig. 2a to 2c show different operating states of the drive unit according to fig. 1 in the case of a split of the drive power to the output device;

fig. 3a to 3c show different operating states of the drive unit according to fig. 1 in the case of recovering at least one of the output powers; and

fig. 4 shows a second exemplary embodiment of an electrohydraulic drive unit according to the invention.

Detailed Description

According to fig. 1, an electrohydraulic drive unit 1 has an electric motor 2 which is connected to a hydraulic machine 6 via a drive shaft 4 for torque transmission. The hydraulic machine 6 has a shaft feedthrough drive 8 which is connected in a rotationally fixed manner to the drive shaft 4. An actuatable clutch 10 is arranged on the shaft feedthrough drive 8, by means of which the shaft feedthrough drive 8 is connected to a rotatable element, in particular a rotary shaft 12 of a rotary mechanism (not shown), by means of which a component of a movable working machine, for example, can be rotated. Alternatively, the shaft 12 can be used instead of a rotary mechanism, for example to drive a traction drive, a fan or another rotating drive. The drive unit 1 also has a brake 14, by means of which the rotational shaft 12 can be braked and/or arrested.

The electrohydraulic drive unit 1 has two hydraulic consumers or outputs 16, 18, which are designed as differential cylinders and can be supplied with pressure medium by the hydraulic machine 6. The hydraulic outputs 16, 18 are arranged in an open hydraulic circuit with the hydraulic machine 6 and the tank T. A hydraulic output 16 is provided for actuating the boom and a hydraulic output 18 is provided for actuating a bucket of a mobile work machine designed as an excavator. The hydraulic machine 6 is in fluid communication with respective bottom spaces 22, 24 of the outputs 16, 18 via a first working line 20. In the individual working lines 26, 28, in each case one metering plate 30, 32 is arranged for distributing the pressure medium volume flow into the respective bottom space 22, 24. The respective rod-side annular chambers 34, 36 of the outlet devices 16, 18 are connected to the tank T via associated return lines 38, 40. In the return lines 38, 40, in each case one brake valve 42, 44 is arranged for throttling the return flow.

The electrohydraulic drive unit 1 according to the invention is designed to split the drive power or shaft power of a drive shaft 4 provided by an electric motor 2. In this case, a partial flow can be carried out onto the drive shaft 8 and onto the hydraulic branch, which is represented by the working line 20. In the illustration according to fig. 1, three operating states of the electrohydraulic unit 1 for driving the work machine are outlined, for example, in a schematic manner. Which correspond to each power flow diagram. The initial point is the supplied drive power P₄The driving power is determined by the rotational speed n of the drive shaft 4₄And a torque M₄And (4) forming. P₆Is the power loss inside the hydraulic machine 6, which consists, for example, of bearing resistance, fluid medium resistance and leakage. P₈Refers to the shaft power of the drive shaft 8. Similar remarks apply to the reference sign P₁₂The drive shaft 12. P₂₀Refers to the hydraulic power in the working line 20, which is composed of the pressure medium volume flow and the pressure of the hydraulic line. P₁₂The net shaft power of the output device 12 provided at the drive shaft of the slewing gear is referred to.

As can be seen from fig. 1, the drive shaft 4 can transmit the drive power to the hydraulic machine 6 and to a through drive 8 of the hydraulic machine. In this way, it is possible to provide, on the one hand, the pressure medium flow of the working line 20 and, on the other hand, the drive torque and the corresponding rotational speed at the rotary shaft 12 of the slewing gear. In other words, on the hydraulic machine 6, the drive power P₄Power divided into hydraulic pressure P₂₀And shaft power P of the machine₁₂. FIGS. 2a to 2c also take into account the power loss P of the hydraulic machine in the figures₆And the power loss P of the direct drive 8₈。

Fig. 2a shows an operating state in which the displacement volume V of the hydraulic machine 6 is present₆Equal to zero. The drive mechanism of the hydraulic machine 6 is accordingly driven with a drive power P₄Is merely "dragged". Power corresponding value P required for towing₆And is smaller. Based on V₆= 0, the loads 16, 18 are not supplied with pressure medium. Hydraulic power P₂₀And is therefore zero. Thus full drive power P₄Reduced power loss P₆Ground is supplied to the feed-through drive 8. If the clutch 10 is closed, this drive power is transmitted 1:1 to the drive shaft 12.

In the operating state according to fig. 2b, the displacement volume V₆Is greater than 0, so that the hydraulic machine 6 delivers the hydraulic power P via the working line 20₂₀To the hydraulic output 16, 18 or to at least one of the outputs. The clutch 10 is simultaneously closed and the drive shaft 12 is powered by power P₁₂The driving mechanism is driven. According to FIG. 2b, the drive power P₄Thus divided into output power P on the hydraulic machine 6₂₀And P₁₂。

According to fig. 2c, an operating state is shown in which the clutch 10 is open. At the same time as the brake 14 is closed, so that the speed n₁₂And = 0. So that the output power P transmitted to the rotating shaft₁₂And = 0. But through the power loss P of the drive 8₈As they existed before. Drive power P₄The power loss P inside the hydraulic machine 6 is then reduced₆Output P of ground as hydraulic pressure₂₀And an output device for providing hydraulic pressure.

According to the invention, an electrohydraulic unit 1 is realized in which the electric motor 2 can also drive the hydraulic machine 6 at least temporarily, so that this hydraulic machine provides a hydraulic power P₂₀. In this case, hydraulic power P can be provided when (as shown in fig. 2 c) the output device 12 (slewing gear) which is otherwise driven by the electric machine 2 is stopped (see fig. 2 c) or when this output device is driven (see fig. 2 b)₂₀。

In the operating state of the mobile working machine (in which no or only a low power P is requested at the drive shaft 12 of the slewing gear)₁₂) The motor 2 outputs no or only a small power to the drive shaft 12. By integration of the hydraulic machine 6 and the division according to the invention, the electric machine 2 can then be used to provide hydraulic power P₂₀. This results in a higher load level of the electric motor 2, so that otherwise necessary additional drives or electric motors and the necessary control elements (e.g. fuel supply, power electronics, controllers) connected thereto can be dispensed with at other points of the movable work machine.

In other words, the electric machine 2 is used for other purposes, in particular for the power supply of other output devices, in phases of smaller power requests of the slewing gear. This synergistic effect can be used to increase efficiency and reduce system cost since the motor 2 is inherently present on the output device 12.

Fig. 3a to 3c show further effects and advantages of the electrohydraulic unit 1 according to the invention. Some operating states are shown in which the power output P is passed₂₀And P₁₂The recovery of (2) is carried out for energy recovery.

According to FIG. 3a, the driving power P is adjusted₁₂To the drive shaft 12. This drive power is derived from the recovered hydraulic output power P converted at the hydraulic machine 6₂₀And a correspondingly reduced drive power P of the electric machine 2 (drive shaft 4)₄And (4) forming. This operating state is achieved in that the hydraulic machine 6 is operated in motoring mode. The pressure medium flows from one or both of the outputs 16, 18 to the hydraulic machine 6 via the working line 20, the pressure medium being reduced in pressure at the drive of the hydraulic machine. The hydraulic power P is thus transmitted to the hydraulic machine 6₂₀Converted into shaft power and added to shaft power P₄。

In the operating state according to fig. 3b, two power branches, namely the hydraulic power branch (20) on the one hand and the mechanical power branch (12) on the other hand, contribute to energy recovery. When under load and at the operatorThis occurs, for example, when the boom connected to the output 16 is lowered and thus under load pressure the pressure medium flows from the piston chamber 22 via the working line 26 to the hydraulic machine 6 and is depressurized there. The rotating rotary mechanism (drive shaft 12) simultaneously transmits the rotational kinetic energy to the drive shaft 8. The hydraulic power P is then₂₀And power P of the machine₁₂Added on the hydraulic machine 6 and transmitted to the drive shaft 4. The output power recovered in this way can then be supplied to the high-power capacitor for storage during generator operation of the electric machine 2.

Fig. 3c shows an operating state in which the drive power P of the electric machine 2 is no matter₄Also the recovered rotational kinetic energy P of the slewing gear₁₂All on the hydraulic press 6 plus the hydraulic power P₂₀. Fig. 3c clearly shows that in this case, a lossy electromechanical conversion and a lossy electrical energy storage can be dispensed with, since the power P fed via the slewing gear is₁₂Is completely absorbed directly by the hydraulic machine 6 and can be fed to the hydraulic reservoir. Thereby minimizing conversion losses.

If the slewing gear does not require the maximum drive power P of the electric machine 2₄The remaining power reserve of the electric motor 2 can then be used to drive the hydraulic machine 6, which is shown in fig. 2 b. If no power is requested by the swing mechanism (at rest), the brake 14 is closed and the clutch 10 is opened. The electric machine 2 can now drive the hydraulic consumers 16, 18 (fig. 2 b) independently of the slewing gear or recover energy from the hydraulic consumers.

If the power demand of the slewing gear rises during the driving of the hydraulic consumers 16, 18 by the electric machine 2 in this way, the clutch 10 is closed again and the rotational speed n of the electric machine 2 is increased₄And the rotation speed n of the slewing mechanism₁₂Is adapted. Depending on the power requirements of the hydraulic machine 6 and the drive shaft 12 (slewing gear), the adapted rotational speed n of the drive shaft 4 is set by a control unit (not shown) of the drive unit 1₄. It is also controlled whether the clutch 10 is locked and therefore operated without slip and without losses, or whether the clutch is operated with slip, for example as a torque converter without lock-up.

In the case of a deceleration of the slewing gear, this slewing gear actively feeds power into the feed-through drive 8 and the drive shaft 4 of the electric machine 2 via the drive shaft 12 (recuperation). This power can be either electrically or hydraulically converted, depending on the control of the electric machine 2 and the hydraulic machine 6. The efficiency of the entire electrohydraulic drive unit can be further increased by this flexibility. Output power P recovered by the method according to FIG. 3c₁₂Direct availability of and the power P to be converted into hydraulic pressure in the hydraulic machine 6₂₀The maximum electrical storage power is also reduced. This reduces the cost of the electrical storage device, in particular of the high-power capacitor.

Fig. 4 shows a second exemplary embodiment of an electrohydraulic unit 101 for a mobile work machine. This electrohydraulic unit contains the electrohydraulic unit 1 according to the preceding fig. 1 to 3 as a subsystem, and therefore a renewed description thereof is not given.

The electrohydraulic unit 101 additionally has a hydraulic circuit which is of the same design as the electrohydraulic unit 1 according to fig. 1, but with the reduction of the through drive 8 and all output-side components, such as the clutch 10, the brake 14 and the drive shaft 12. The purely hydraulic circuit thus has a second electric machine 102, a second hydraulic machine 106 connected via a second drive shaft 104, and second hydraulic consumers or outputs 116, 118 which can be supplied with pressure medium via the second hydraulic machine. The pressure medium supply via the second hydraulic machine 106 and the pressure medium discharge to the tank T (including the valves required for this purpose) are constructed identically to the electrohydraulic unit 1 according to fig. 1.

The electrohydraulic unit 101 according to fig. 4 additionally has a connecting line 46 with a summation valve 48, via which the working lines 20, 120 of the two hydraulic machines 6, 106 can be brought into fluid communication with one another. The aforementioned functions of power splitting and power summing at the hydraulic machines 6 of the components of the aforementioned electrohydraulic unit 1 also remain in the second exemplary embodiment. The second hydraulic outputs 116 and 118 can be driven independently of the electrohydraulic unit 1 by the second electric machine 102 and the hydraulic machine 106. In the case of one or a subset of the output devices 16, 18, 116, 118 requiring more hydraulic power than can be provided by the respectively associated one of the hydraulic machines 6, 106, the respective other of the hydraulic machines 106, 6 can be connected via the connecting line 46 and the valve 48.

Similar explanations apply to the recovery of hydraulic power. If the hydraulic power is to be stored separately electrically, this can be done, for example, by only one of the electric machines 2, 102 in such a way that all of the pressure medium volume flow is reduced by the hydraulic machine 6 or alternatively by the hydraulic machine 106 via the connecting line 46 and the valve 48.

In the case of recuperation of hydraulic energy for direct drive of the drive shaft 12 of the slewing gear, the pressure medium volume flow of the second hydraulic output 116, 118 must be reduced via the hydraulic machine 6 via the connecting line 46 and the valve 48.

The invention relates to an electrohydraulic drive unit for a mobile work machine, in particular for a crane or excavator, having a hydraulic output and a machine output, wherein the latter can be driven by an electric motor of the drive unit. According to the invention, the drive power of the drive unit can be split completely or in portions not only to the mechanical output but also to at least one further output.