MOBILE WORK MACHINE, ESPECIALLY WHEEL LOADERS, WITH TWO ELECTRIC MOTORS

Description

[0001] The invention relates to a mobile work machine, in particular a wheel loader, telescopic loader, excavator, dumper, tractor or the like, with a vehicle frame and with a drive unit for driving at least one drive element, according to the preamble of claim 1. State of the art

[0002] Mobile work machines, especially wheel loaders, telehandlers, excavators, tractors, or the like, with a vehicle frame and a drive unit for driving at least one drive wheel, are still mostly powered by liquid fuel today. Diesel-powered vehicles are currently the primary vehicles used. Electrically powered machines with a rechargeable battery or electrical energy storage system are now in use.

[0003] These mobile work machines typically feature detachably connectable work tools, e.g., which are held or released using so-called "quick couplers" or "interchangeable plates." These work tools are often mounted on a lifting arm, telescopic arm, or similar device. To raise and / or lower these tools, as well as the partially actively driven tools such as grab buckets, brooms, etc., these components are powered electrically in so-called "fully electric" machines, while in so-called "hybrid" machines, these components are powered by a hydraulic system.

[0004] DE 20 2014 000 738 U1 describes such a work machine, in which an electric drive motor or electric motor drives a hydraulic pump to operate the hydraulic tool. A second, central electric motor drives the drive / running wheels or the rear / front axles via a transfer case. Alternatively, a central electric drive with hydraulic conversion and hydraulic wheel hub drive is also used today.

[0005] In order to avoid using high-torque or expensive electric motors, a certain minimum gear ratio between the electric motor and the impeller and thus an additional gearbox is necessary.

[0006] Another disadvantage of existing mobile work machines is that, in addition to the transmission, a cardan shaft must be used. These are comparatively heavy, require a lot of space, and result in a disadvantageous overall height. The aforementioned hydraulic alternative allows for a lower overall height, but due to its design, it is less efficient.

[0007] In the publications US 2020 / 0391582 A1 and WO 2020 / 187906 A1, work machines with two electric motors are already known. Object and advantages of the invention

[0008] The object of the invention is, in contrast, to propose a mobile work machine, in particular a wheel loader, telescopic loader, excavator, dumper, tractor or the like, which at least partially improves the disadvantages of the prior art, in particular by optimising the vehicle's centre of gravity and / or weight distribution and / or by realising a drive system with novel operating modes.

[0009] This object is achieved by the features of claim 1, starting from a mobile work machine of the type mentioned in the introduction. Advantageous embodiments and further developments of the invention are possible through the measures mentioned in the subclaims.

[0010] Accordingly, a mobile work machine according to the invention, in particular a wheel loader, telescopic loader, excavator, dumper, tractor or the like, comprises at least one vehicle frame and a drive unit for driving at least one first drive element and one second drive element, such asDrive wheel / roller and / or tracked chassis or vibration element, wherein at least one first electric motor and one second electric motor as well as at least one electrical energy storage device for storing electrical energy at least for the electric motors are provided, wherein the drive unit comprises at least the first electric motor, wherein at least one control unit for the electrical and / or electronic control of the electric motors and / or the energy storage device is provided, wherein at least one tool holding device is provided for holding a work tool and / or wherein the drive unit comprises at least one hydrostatic drive motor driven by the electric motor for driving the drive element and / or the work tool and / or the tool holding device, wherein in particular the tool holding device has at least one support device pivotable about a pivot axis, e.g.Lifting arm and / or telescopic boom and / or three-point lifting device, and in that the drive unit comprises at least the first electric motor for driving the first drive element and the second electric motor for driving the second drive element, wherein the first drive element is arranged on a front axle of the work machine and the second drive element is arranged on a rear axle of the work machine. In this way, a front-wheel, rear-wheel, or all-wheel drive can be advantageously realized. A transfer case between or for connecting the front and rear axles, as in the prior art, is dispensable. This reduces the effort as well as costs and weight.

[0011] The first electric motor and the second electric motor can be used to drive the work machine. This represents a departure from previously widespread systems, in which a first electric motor was intended to drive the drive wheels / chains, and the second electric motor was merely a so-called starter for an internal combustion engine or for the hydraulic system or the work tool, but could not be used to drive or operate the work machine.

[0012] With the help of the two electric drive motors, completely new operating modes can be realized. For example, the first electric motor is operated with a different motor power and / or torque than the second electric motor and / or operated individually, especially at different times or in different operating phases, or in combination with each other, especially simultaneously.

[0013] For example, the first electric motor has a first motor power and a first motor torque and a first motor volume, wherein the second electric motor has a second motor power and a second motor torque and a second motor volume, and wherein the first motor power is less than or greater than the second motor power and / or the first motor torque is less than or greater than the second motor torque and / or the first motor volume is less than or greater than the second motor volume. This advantageous difference between the two drive motors results in a wide variety of advantageous possibilities for combining them or for the respective individual operation / drive for the work machine according to the invention, in particular with the aid of the control unit. This means that, among other things, three very different drive powers / torques are available for very different tasks, applications, etc., namely e.g.a smaller or larger drive power and a combined or combined drive power. The machine can be operated accordingly in an energy-efficient and fuel-efficient manner.

[0014] In principle, the two drive motors can be arranged / attached or mounted directly, i.e. without a gearbox / transmission ratio, on the respective drive element or drive wheel. This saves installation space and costs. Advantageously, at least one first gear unit with a first drive of the first electric motor, which has a first input speed, and a first output having a first output speed is provided on the first electric motor and / or at least one second gear unit with a second drive of the second electric motor, which has a second input speed, and a second output having a second output speed is provided on the second electric motor. This advantageously enables a conversion of the torque and / or the speed. This is particularly advantageous for heavy work where very high torques are required.This allows the electric motors to be dimensioned accordingly smaller and particularly economically. Nevertheless, a high torque can be provided to the working machine. For example, the first output speed of the first output of the first gear unit is lower or higher than the second output speed of the second output and / or a first torque of the first output of the first gear unit is lower or higher than a second torque of the second output.

[0015] In an advantageous variant of the invention, the drive unit and / or a first / second drive chain comprises at least the first and / or second gear unit, wherein the first gear unit, in particular within the first drive chain, is arranged at least between the first electric motor and the first drive element, such that a first driving force of the first electric motor, in particular within the first drive chain, can be transmitted to the first drive element via the first gear unit, and / or wherein the second gear unit, in particular within the second drive chain, is arranged at least between the second electric motor and the second drive element, such that a second driving force of the second electric motor, in particular within the second drive chain, can be transmitted to the second drive element via the second gear unit. Advantageous drive chains can thus be realized.

[0016] Advantageously, at least one first clutch unit is arranged between the first drive element and the first electric motor for coupling and uncoupling the first electric motor and / or the first transmission unit from the first drive element, and / or at least one second clutch unit is arranged between the second drive element and the second electric motor for coupling and uncoupling the second electric motor and / or the second transmission unit from the second drive element. In particular, at least one actuating device is provided for actuating the first and / or second clutch unit. This advantageously allows one or both electric motors or drive elements to be coupled or uncoupled, allowing a wide variety of component combinations to be implemented depending on the work to be carried out. This leads to particularly efficient operation of the work machine.

[0017] In a particular development of the invention, the first electric motor is designed as a first generator unit for generating electrical energy and / or the second electric motor is designed as a second generator unit for generating electrical energy. Thus, the electric motors can be used as an energy generator and / or brake for the work machine, as needed.

[0018] Advantageously, at least one sensor element is provided for detecting at least one of the rotational speeds and / or a speed. This advantageously allows parameters of the working machine to be detected and further used, particularly with the aid of the control unit. For example, the control unit is designed to actuate the actuating device and / or to operate the two electric motors depending on one of the rotational speeds and / or the speed.

[0019] In an advantageous embodiment of the invention, at least one pump motor is provided for driving a hydraulic pump of a hydraulic system comprising a hydraulic fluid, wherein in particular the pump motor and / or the hydraulic pump and / or the hydraulic system is designed to operate the work tool and / or the tool-holding device and / or the carrying device. This allows a hydraulic system to be implemented in addition to the electric drive system, which is of great advantage, among other things, for the carrying device or the lifting arm and / or the tool-holding device or the work tool. Thus, for example, previously conventional active or hydraulic work tools can continue to be used.

[0020] In addition, a differential and / or a separate braking system of the working machine can be advantageously used. In so-called purely electric drives, recuperation with the electric motor is currently not approved as sufficiently safe, so a separate braking system must be provided (in addition). Advantageous, for example, are brakes that are directly assigned to a drive element or impeller and located on the respective hub.

[0021] For example, a mobile work machine comprises at least one operatively connected brake row, in particular consisting of a brake element of the brake unit and the transmission unit, as well as the at least one drive element / impeller, wherein the transmission unit is arranged in / within the brake row at least between the at least one drive element / impeller and the brake element, so that a braking force of the brake unit and / or the braking element can be transmitted via the transmission unit to the at least one drive element / impeller. With the help of this advantageous brake row or "brake chain," on the one hand, the braking force or braking torque can be advantageously converted or changed / increased by means of the transmission unit. On the other hand, the transmission unit is also used / used twice, so that the economic or design effort is saved, and the required installation space is advantageously kept small or minimal.can be small.

[0022] It is precisely the advantageous transformation of the braking force / braking torque of the braking unit or the braking element by means of the gear unit, so that a comparatively large braking force or braking torque on the impeller and thus a comparatively strong / powerful braking of the mobile work machine such as a wheel loader or the like can be realized, which enables a particularly small-sized and cost-effective braking unit or braking element.

[0023] However, it is also conceivable in principle that the brake unit could advantageously be arranged or operated in series with / to the electric motor on the transmission unit. Thus, in this conceivable case, the electric motor is arranged / integrated between the brake unit and the transmission unit, or alternatively, the brake unit is arranged / integrated between the electric motor and the transmission unit, both spatially and in terms of the chain of action or the effective connection.

[0024] In an advantageous variant of the invention, an operatively connected drive train is provided, consisting of the electric motor and the transmission unit, as well as the at least one drive wheel. Within the drive train, the brake unit is arranged between the electric motor and the differential unit or the at least one drive wheel. This is particularly cost-effective and space-saving.

[0025] Advantageously, the input speed of the drive of the gear unit is greater than the output speed of the output, so that the gear unit has a reduction ratio. The advantageous transformation of the braking force / torque of the braking unit or braking element achieved by the gear unit generates a comparatively large braking force or braking torque on the impeller, thus enabling comparatively strong / powerful braking with a relatively small braking unit. This enables a particularly cost-effective implementation of the invention.

[0026] Advantageously, a central drive shaft can be omitted, which can lead to a particularly cost-effective and space-saving implementation of the invention.

[0027] Preferably, the drive unit comprises at least the transmission unit, wherein the transmission unit is arranged at least between the electric motor and the drive wheel, so that a driving force of the electric motor can be transmitted via the transmission unit to the at least one drive wheel. This enables a particularly advantageous drive chain or operative connection of the most relevant drive components.

[0028] In a preferred variant of the invention, the energy supply of the electric motor of the axle or the travel drive and in particular of the entire work machine and thus also, if applicable, of the (active) tool and the often present lifting arm, telescopic arm, lifting device or the like is provided from the electrical energy storage device or battery.

[0029] In a particular embodiment of the invention, at least one pump motor is provided for driving a hydraulic pump of a hydraulic system comprising a hydraulic fluid. This allows for an advantageous hybrid mode of operation, e.g., with an electric drive of the work machine or an electric motor as a converter of the electrical energy of the electrical energy storage device with a hydraulic pump driven by the latter, which drives a hydraulic drive / motor, and / or hydraulic operation of the tool and / or the adjustable / rotatable / movable support device, such as a lifting arm, telescopic arm, or the like.

[0030] In the latter case, the pump motor and / or the hydraulic pump and / or the hydraulic system are advantageously designed to operate the work tool and / or the tool holding device and / or the carrying device. Thus, the advantages of a hydraulic operation of the carrying device or the lifting arm, telescopic arm, etc., and / or a hydraulic, active tool such as a gripper arm, etc., can be advantageously combined with an electric drive of the mobile work machine according to the invention.

[0031] For example, the mobile work machine features advantageous steering or adjustability of the individual wheels, for example, to achieve all-wheel steering of the work machine. Preferably, at least one articulated steering system is provided. This allows the use of articulated steering, which has proven particularly successful in wheel loaders, or of conventional vehicle frames or bodies, which has a beneficial effect on costs and operating mode / costs.

[0032] It is generally advantageous to design at least one of the two electric motors so that it can be decoupled, e.g. with an electromagnetic or hydraulic clutch. This can, among other things, reduce energy losses via the second or switched off motor. It should be advantageous to be able to switch off at least the motor that is dimensioned or intended for low speeds. This can, for example, make it possible to achieve a high top speed without the motor for slow travel speeds or with high torques having to be dragged along. The second motor for higher travel speeds can, if necessary, also have a clutch so that it can support the second motor even when traveling slowly.

[0033] For example, a high-torque motor can be fitted to the front axle, particularly with a higher gear ratio. The high torque is particularly advantageous on the front axle, for example, when driving into a pile of debris or similar, providing plenty of thrust to fill the tool or bucket. A motor with lower torque or a lower gear ratio can be fitted to the rear axle. This typically results in different (maximum) motor speeds. When driving at high speeds, the faster-rotating motor can be decoupled to protect the components from damage.

[0034] In general, electric motors can be advantageously optimized or designed for different operating points. This results in a point of optimal efficiency for each motor, at which it can be operated if possible.

[0035] Advantageously, an electronic control or monitoring system is provided, which monitors various parameters and controls the motors in an advantageous manner. For example, the following could be monitored: the speeds of the electric motors and / or a current consumption of the motors and / or a recuperation of the motors or a generated current and / or a temperature, e.g. to protect a motor if its temperature is too high and it should not / may not be controlled, and / or the speed of the working machine or the vehicle and / or the speed of the final drive, e.g. via a sensor in the transmission of an axle.

[0036] The control or monitoring system can be designed to achieve the best possible utilization of both motors. For example, the control or monitoring system can control the motors using a characteristic map or similar.

[0037] A road mode or overdrive mode is advantageously provided. This allows for a high top speed and / or the use of the engine with a lower gear ratio. For example, both engines can be used for starting off to achieve high torque. A favorable work mode or crawler mode can also be provided. Thus, the use of both engines can be particularly advantageous here to achieve optimal traction. Alternatively, the engine with a high gear ratio can also be provided for this purpose.

[0038] Advantageous switching between different operating modes can either occur automatically, e.g., below a specified driving speed, the work mode can be used automatically. Above this limit, a switch to fast or road mode can be implemented (automatically). Alternatively, or in combination with this, a (manual) switch or

[0039] The user can preselect the speed. Typically, the switchover occurs at approximately 7-15 km / h.

[0040] For example, a previously deactivated motor can be switched on / engaged when the brake is applied and / or the driver releases the accelerator. If, for example, the motor with a higher gear ratio was previously deactivated, this now creates the opportunity to recuperate more energy and thus drive / operate more efficiently. Example

[0041] An embodiment of the invention is shown in the drawing and is explained in more detail below with reference to the figures.

[0042] In detail: Figure 1 shows a schematic view of a mobile work machine with driver's cab, vehicle frame and energy storage device according to the invention, Figure 2 shows a schematic plan view of the vehicle frame with two electric drive motors of the mobile work machine according to Figure 1 and Figure 3 a schematic, perspective view of the vehicle frame of the mobile work machine according to Figure 1 and without a driver's cab.

[0043] The figures schematically depict a mobile work machine 1 with a driver's cab 2, a vehicle frame 3, and an energy storage unit 4 or a traction battery 4, designed as a so-called telescopic loader with a telescopic arm 6 and four steerable wheels 5, i.e., with all-wheel steering. The energy storage unit 4 or the traction battery 4 supplies two electric motors 7, each of which drives the wheels 5 via a transmission gear 8.

[0044] The electric motors 7 are preferably each connected to an associated axle 25 by means of a coupling 22, which drives the running wheels 5. The driven running wheels 5 can thus be driven either as front wheels or as rear wheels, in particular for front-wheel, rear-wheel, or all-wheel drive.

[0045] Merely symbolic is Figure 2A hydraulic pump or hydraulic system 10 is depicted to demonstrate that, for example, the telescopic arm 6 can be adjusted, raised, and extended / retracted using hydraulic energy. However, such hydraulic systems are generally known.

[0046] The energy storage device 4 or a storage housing 9 is arranged or fixed at the bottom of the supporting frame 3, whereby a plate 11 is fixed below the housing 9 or energy storage device 4 to the vehicle frame 3, in particular releasably fixed, e.g., by means of screws. Advantageously, a damping element 18 is provided for damping the energy storage device 4 or the traction battery 4, which can cushion / damp vibrations. At the same time, the housing 9 also serves as protection against dirt and water.

[0047] The energy storage device 4 or the traction battery 4 further comprises an inverter 20 and / or an electronics unit 12 and / or a so-called battery management system (BMS) 21, which is provided for controlling the discharge and charging of the energy storage device 4 or the traction battery 4.

[0048] The energy storage device 4 or the traction battery 4 has numerous battery cells 14 (see in Figure 1 and 3 indicated), which are arranged within two battery modules 13 in the present embodiment. The battery cells 14 are all arranged on a common plane 15 within the housing 9 or energy storage device 4. A liquid cooling system 16 and a damping system 18 or damping elements 18 are provided below the cells 14 and above or within the housing 9.

[0049] In addition, a charger or charging unit, an air conditioning compressor, one or more DC / AC converters 17 and / or a fuse 23 and / or an inverter, etc. may also be present within the housing 9 or the energy storage device 4 or the traction battery 4.

Claims

1. Mobile working machine (1), in particular wheel loader, telescopic loader, digger, dumper, tractor or the like, having a vehicle frame (3) and having a drive unit for driving at least one first drive element (5) and one second drive element (5), e.g. drive wheel / roller and / or crawler track or vibration element, wherein at least one first electric motor (7) and one second electric motor (7) and at least one electrical energy store (4) for storing electrical energy at least for the electric motors (7) are provided, wherein the drive unit comprises at least the first electric motor (7), wherein at least one control unit (12, 17, 20) for electrically and / or electronically controlling the electric motors (7) and / or the energy store (4) is provided, wherein at least one tool-holding device (6) for holding a working tool is provided, and / or wherein the drive unit comprises at least one hydrostatic drive motor, which is driven by the electric motor (7), for driving the drive element and / or the working tool and / or the tool-holding device (6), wherein in particular the tool-holding device (6) comprises at least one supporting device which is pivotable about a pivot axis, e.g. lifting arm and / or telescopic boom and / or three-point lifting device, wherein the drive unit comprises at least the first electric motor (7) for driving the first drive element (5) and the second electric motor (7) for driving the second drive element (5), characterized in that the first drive element (5) is arranged on a front axle (25) of the working machine (1) and the second drive element (5) is arranged on a rear axle (25) of the working machine (1).

2. Working machine according to Claim 1, characterized in that the first electric motor (7) has a first motor power and a first motor torque and a first motor volume, and in that the second electric motor (7) has a second motor power and a second motor torque and a second motor volume, wherein the first motor power is smaller or greater than the second motor power and / or the first motor torque is smaller or greater than the second motor torque and / or the first motor volume is smaller or greater than the second motor volume.

3. Working machine according to either of the preceding claims, characterized in that at least one first transmission unit (8) with a first drive of the first electric motor (7) having a first driving rotational speed and with a first output having a first output rotational speed is provided on the first electric motor (7), and / or in that at least one second transmission unit (8) with a second drive of the second electric motor (7) having a second driving rotational speed and with a second output having a second output rotational speed is provided on the second electric motor (7).

4. Working machine according to Claim 3, characterized in that the first output rotational speed of the first output of the first transmission unit (8) is smaller or greater than the second output rotational speed of the second output of the second transmission unit (8).

5. Working machine according to either of Claims 3 and 4, characterized in that a first torque of the first output of the first transmission unit (8) is smaller or greater than a second torque of the second output of the second transmission unit (8).

6. Working machine according to one of Claims 3 to 5, characterized in that the drive unit comprises at least the first and / or second transmission unit (8), wherein the first transmission unit (8) is arranged at least between the first electric motor (7) and the first drive element (5) such that a first driving force of the first electric motor (7) can be transmitted via the first transmission unit (8) to the first drive element (5), and / or wherein the second transmission unit (8) is arranged at least between the second electric motor (7) and the second drive element (5) such that a second driving force of the second electric motor (7) can be transmitted via the second transmission unit (8) to the second drive element (5).

7. Working machine according to one of the preceding claims, characterized in that between the first drive element (5) and the first electric motor (7) there is arranged at least one first coupling unit (22) for coupling and uncoupling the first electric motor (7) and / or the first transmission unit (8) to and / or from the first drive element (5), and / or in that between the second drive element (5) and the second electric motor (7) there is arranged at least one second coupling unit (22) for coupling and uncoupling the second electric motor (7) and / or the second transmission unit (8) to and / or from the second drive element (5).

8. Working machine according to one of the preceding claims, characterized in that at least one actuating device for actuating the first and / or the second coupling unit (22) is provided.

9. Working machine according to one of the preceding claims, characterized in that the first electric motor (7) is designed as a first generator unit for generating electrical energy, and / or in that the second electric motor (7) is designed as a second generator unit for generating electrical energy.

10. Working machine according to one of the preceding claims, characterized in that at least one sensor element for sensing at least one of the rotational speeds and / or for sensing a speed is provided.

11. Working machine according to one of the preceding claims, characterized in that the control unit (12, 17, 20) is designed for actuating the actuating device depending on one of the rotational speeds and / or the speed.

12. Working machine according to one of the preceding claims, characterized in that at least one pump motor (10) for driving a hydraulic pump of a hydraulic system comprising a hydraulic fluid is provided, wherein in particular the pump motor (10) and / or the hydraulic pump and / or the hydraulic system are / is designed for operating the working tool and / or the tool-holding device (6) and / or the supporting device.

13. Method for operating a working machine according to one of the preceding claims, characterized in that the first electric motor (7) and the second electric motor (7) are used as a drive (7) for the working machine (1), wherein in particular the first electric motor (7) is operated with a different motor power and / or a different motor torque from the second electric motor (7).