DE202021105282U1 - Electric drive structure for a work machine - Google Patents

Abstract

Electric drive structure for a work machine, in particular for a tractor, comprising:
a front axle (2) with two front wheels (4);
a rear axle (3) with two rear wheels (5);
a first electric drive (6) for generating a drive torque for driving the front wheels (4);
a second electric drive (7) for generating a drive torque for driving the rear wheels (5); and
a coupling between the first electric drive (6) and the second electric drive (7), via which the drive torque of the first and second electric drive (6, 7) can be variably transmitted between the front axle (2) and the rear axle (3) .

Description

TECHNICAL AREA

The present invention relates to an electric drive structure for a work machine, in particular for a tractor. That is, a structure that can electrically drive a work machine is disclosed.

BACKGROUND

Various utility vehicles, work machines and agricultural machines are already known, such as tractors, excavators, mobile cranes, forklifts, mobile lifting platforms, snow clearing vehicles, sugar beet harvesters and combine harvesters.

Nowadays these usually have a diesel engine as the drive motor. This means that the diesel engine is used to drive the drive wheels and, in some cases, also for other functions, such as driving a so-called alternator to generate electricity or energy for various smaller consumers such as light, radio, ventilation, sensors, etc.

In addition, so-called power take-off shafts are often provided in work machines or agricultural machinery, which serve to drive additional equipment by means of drive torque generated by such a diesel engine. In this way, for example, a torque can be transmitted to a trailer connected to a tractor and the drive torque can be used for other devices. As an example of this, reference is made to a potato harvester which uses the torque generated by the diesel engine to use conveyor belts and the like on the trailer for harvesting potatoes.

Disadvantages here, however, are the large amount of space required by the diesel engine in such a work machine and the poor efficiency in real operation.

In addition, with increasing political pressure - against the background of existing climate change - the high energy consumption as well as the generation of exhaust gases and the environmental pollution caused by the diesel engine are particularly disadvantageous.

Accordingly, there is an interest in alternative and more sustainable drive systems in many areas of mobility.

In the meantime, drives using fuel cells, electric motors, which use batteries for energy storage, or hybrid designs of electric motors and fuel cells or electric motors and internal combustion engines have become established.

In the field of mobile and agricultural machines, electrical power transmissions offer particular advantages. Here, for example, due to the good controllability and regulation of the electrical drives, the usage properties can be significantly increased.

Against this background, working machines or agricultural machines, for example tractors, are known in which both the travel drive and at least one power take-off shaft (as a power take-off) are implemented via separate electrical drives. The energy required for this is typically generated by an internal combustion engine and a (current) generator coupled to it. In addition, “only” one battery can be provided which supplies the electric drives with energy. Alternatively, a fuel cell can replace the internal combustion engine and the generator. An energy storage device can also be provided for storing electricity, so that smaller or shorter activities can be carried out fully electrically.

In such a previously known embodiment, a mechanical connection between the internal combustion engine, which is used to generate electricity, and the drive train of the tractor, for example for a travel drive and / or a power take-off shaft, can be dispensed with. That is, in a previously known electric drive structure for such a work machine, a front axle with two front wheels and a rear axle with two rear wheels can be provided. In addition, such a previously known electric drive structure has an electric drive for generating a drive torque for driving the front wheels and the rear wheels. Furthermore, there are known electric drive structures which have a separate electric drive for generating a drive torque for driving the front wheels and a separate electric drive for generating a drive torque for driving the rear wheels.

Furthermore, at least one further electric drive can be provided for generating a drive torque for driving at least one power take-off shaft.

In such a configuration, the electrical drives must be designed appropriately in terms of power, ie the required torque, in order to be able to cover extreme operating or usage situations in addition to the nominal operating modes. Such a previous design is required In this case, therefore, a design of the electrical drives with an eye to the maximum performance requirements, which leads to increased costs due to an over-design of the electrical drives.

Such usage situations with high loads for the electrical drives in agricultural machinery can consist of, among other things, heavy pulling and pushing work in adverse soil conditions and / or an unfavorable weight distribution on the towing vehicle.

Examples of such pulling and pushing work are plowing, moving timber and front loader work. In such activities it can happen that an effective propulsion takes place through only one driven axle or even through only one single driven wheel. In such situations, however, it is also necessary that the provided electric drive on the, for example, individual still effectively drivable axis is able to still operate the work machine in such a situation and to prevent it from getting stuck in adverse ground conditions.

Thus, previously known designs are aimed at larger, more powerful and therefore particularly cost-intensive electric drive structures.

Furthermore, previously known embodiments must be able to withstand a wide spread between high starting torque of such a work machine and high top speed. This also leads to the need to use more powerful and larger electric drives. This leads to a higher cost of such a work machine.

Furthermore, working machines or agricultural machines with an electric single wheel drive are already known. With a view to the above embodiments, a drive of the respective wheels can indeed be implemented individually, but due to the above-described, necessary design of such electrical drives for extreme load situations, it is particularly costly and structurally complex.

In addition, in such work machines it is often not only necessary to drive the respective wheels, but also to supply power to the PTO shafts provided for other devices and equipment that can be coupled to these work machines. This means that additional electrical drives with a corresponding design must be provided on a work machine for these power take-offs.

In order to counteract this, an agricultural hybrid vehicle is disclosed, for example, in WO 2020/165 393 A1, a diesel engine also driving an electrical generator here, which outputs energy to power electronics. This electrical energy is transmitted through the power electronics to a first electrical drive, which in turn transmits torque to a drive train and thereby drives the wheels of such an agricultural hybrid vehicle. In addition, a further electric drive is provided, which can transmit torque to a power take-off shaft via a second, individual drive train. In addition, batteries are provided in this agricultural machine, which can be charged.

In addition, WO 2020/165 393 A1 discloses a third electric drive which can also be supplied with energy by the power electronics and can deliver torque to a distributor unit. Such a distribution unit is connected to the drive train of the wheels and the second drive train of the power take-off shaft.

In other words, a third electric drive can be connected to two individual drive trains and thus support the first and second electric drives, which drive the wheels and the power take-off, in a torque-transmitting manner.

However, such a configuration is not only complex, but also requires the provision of a large number of mechanical interconnections and drive trains. In addition, the first electric drive, which drives the wheels via the first drive train, is far from the place of operation, that is, the axles or the wheels, so that higher transmission losses can occur in such a configuration.

DISCLOSURE OF THE INVENTION

It is therefore the object of the present invention to reduce or eliminate the problems described above. Another task is to provide an electric drive structure for a work machine, which is cost-effective and satisfactory without disproportionately excessive design of the electric drives - even in extreme usage situations, such as heavy pulling and pushing work in adverse soil conditions and / or an unfavorable weight distribution on the work machine functions.

This object is achieved by an electric drive structure for a work machine with the features of claim 1. Preferred configurations can be found in the further claims of the following description and drawings.

According to one embodiment, an electric drive structure for a work machine has a front axle with two front wheels and a rear axle with two rear wheels. Furthermore, a first electric drive for generating a drive torque for driving the front wheels and a second electric drive for generating a drive torque for driving the rear wheels are provided.

Further driven axles with associated electric drives for generating a drive torque for driving the wheels of the respective axle can also be implemented. Thus, not only vehicles with 4x4 drive, but also, for example, vehicles with 6x6 axle drive and 8x8 axle drive can be implemented.

In addition, a coupling is provided between the first electric drive and the second electric drive, via which the drive torque of the first and second electric drive can be variably transmitted between the front axle and the rear axle.

The core idea of the present invention is based on the fact that the electrical drives provided in isolation and close to the locations of action do not have to be designed for extreme cases. Rather, the present invention allows, for example, in extreme usage situations, to variably combine the drive torques of the first and second electric drives and possibly further electric axle drives and other drives (power take-offs or power take-offs).

In other words, the drive torques generated by the first and second electric drive can be mixed with one another due to the coupling and used or switched on in a manner appropriate to the situation.

Furthermore, according to such a configuration, in contrast to previously known devices which disclose hybrid drive structures with an additionally connectable electric motor, it is possible to prevent tension from occurring between the front and rear axles. This is more gentle on the soil and reduces the risk that a machine could dig itself into the ground when the vehicle is in motion. Accordingly, deterioration of crops can be prevented. This is made possible by the single-axis drives described above.

In addition, the design can provide a more cost-effective electric drive structure for a work machine, since the electric drives no longer have to be correspondingly oversized and, for example, high torques can be easily applied to one axis by mixing in the torque of a second electric drive when working backwards. That is, a load distribution between the first and second electric drive can be provided.

If, for example, due to an unfavorable weight distribution, the effective propulsion transmission of a work machine only takes place through a single driven axle (for example the rear axle), then for example the drive torque of the first electric drive can be transferred to the second electric drive to generate a drive torque for driving the rear wheels (i.e. the Rear axle). This is also to be understood as an admixture of the drive torque and no pure / complete transmission to the rear axle.

A reverse configuration, that is to say support for the first electric drive by the second electric drive, is also to be understood by this.

Thus, when designing the electric drives according to the present drive structure for a work machine, less powerful and thus more cost-effective electric drives can also be used.

Accordingly, an electric drive structure can be generated for a work machine, which has separate axle drives and can be designed to be particularly cost-effective.

The clutch described in the present case is a device in which the torque can be variably transmitted between the electric drives on the respective axles.

This means that the coupling described in the present case can be a simple machine element for rigid, elastic, movable or detachable connection of two shafts in order to transmit rotation and thus torque and ultimately mechanical work, as well as a coupling, which is not only releasable and lockable, but can variably transmit torque between the first electric drive and the second electric drive.

The variable coupling is preferably not just a machine element for rigid, elastic, movable or releasable connection of two shafts in order to transmit rotation and thus torque and ultimately mechanical work, but rather also a coupling that is not only releasable and can be closed, but can variably transmit torque between the first electric drive and the second electric drive.

The first electric drive is preferably arranged on the front axle. It is also preferred that the second electric drive is arranged on the rear axle.

Accordingly, transmission losses of the electric drives can be minimized, since the first and second electric drives are provided close to the target location.

Driving operation, that is to say driving the wheels of a work machine, can be understood as the target place of action.

Furthermore, the first electric drive can be designed to drive the front axle and thereby the front wheels, and the second electric drive can be designed to drive the rear axle and thereby the rear wheels.

Accordingly, an axle drive can be generated with an electric drive arranged directly on the axle on the front axle and the rear axle. Thus, with a simple structure, an axle drive can be generated which can drive the work machine with a simple structure in a sustainable manner.

Alternatively, the first electric drive can have two electric motors, each of the electric motors of the front axle being designed to individually drive a front wheel on the front axle. Furthermore, the second electric drive can have two electric motors, each of the electric motors of the rear axle being configured to drive a rear wheel individually.

According to such an embodiment, the respective drive situation on the respective wheels on the front and rear axles can be controlled even more appropriately and the load can be distributed among the respective electric motors by means of the clutch of the four individual wheel drives. This means that in extreme situations, in which, for example, an effective propulsion takes place through only a single driven wheel, the torque of the ineffective electric motors can be switched to the maximally loaded electric motor. Accordingly, the design of the individual electric motors can be smaller.

Furthermore, a transmission can be provided between the first electric drive and the second electric drive, via which the drive torque of the first and second electric drive can be transmitted and translated between the front axle and the rear axle.

This is particularly advantageous if there is a torque-transmitting connection between the first and second electric drives and the electric first and second drives provided on the respective axles have front wheels and rear wheels with different wheel diameters on the driven axles. In other words, the transmission can synchronize or adapt the torque and speed between the first electric drive and the second electric drive.

Furthermore, the electric drive structure can have a third electric drive for generating a drive torque for driving a first power take-off shaft.

In addition, the electric drive structure can furthermore have a fourth electric drive for generating a drive torque for driving a second power take-off shaft.

According to such an embodiment, an electric drive structure can be provided which provides for an individual electric control of independent electric drives on the front and rear axles as well as the power take-off shafts.

The third and / or fourth electric drive is preferably mechanically coupled directly or indirectly to the coupling so that the drive torques of the electric drives are variably transmitted between the first electric drive, the second electric drive, the third electric drive and / or the fourth electric drive can.

This is particularly advantageous because the respective electric drives can thus be designed to be smaller and therefore more compact, that is to say with less power, and are therefore more cost-effective. In addition, such a configuration enables unused electrical drives, for example the power take-off shafts, to be switched to the first and second electrical drives on the front and rear axles to generate propulsive power.

In addition, due to such a configuration, it is possible for particularly torque-intensive activities, for example when standing (e.g. when working backwards), that the drive torque of the first electric drive and the second electric drive is transferred to the third and / or fourth electric drive can be activated.

Thus, for example, the electric drives of the first and second PTO shafts can "support" each other when one of the two is not required.

During activities while stationary, the "support" can also be provided by the first and second electrical drives if the required speed ratios of the third and / or fourth electrical drive of the PTO shaft (s) and the first or second electrical drive through the coupling match each other. Furthermore, the first and / or second electric drive can be decoupled from the front axle or rear axle. This can be achieved, for example, by using additional (rigid) couplings.

Such a configuration thus enables a more flexible and at the same time more cost-effective electric drive structure for a work machine.

The mechanical coupling can preferably take place via a switchable gear arrangement.

Correspondingly, if there is no need for further torque, the electric drives of the power take-off shafts, that is, the third electric drive and the fourth electric drive, from the electric drive structure provided for the propulsive power of the clutch, the first electric drive and the second electric To decouple the drive. Correspondingly, additional friction losses or the like due to a mechanical coupling can be avoided when not required, and an efficient design can thus be achieved.

Furthermore, the electric drive structure can have an internal combustion engine, in particular a diesel engine and / or a fuel cell and / or a battery for generating electrical energy, in order to supply the first and second electrical drives with electrical energy. According to such an embodiment, a generator can be provided on the internal combustion engine, for example, so that a mechanical coupling of the internal combustion engine and the travel drive, which is implemented by the first electrical drive and the second electrical drive, can be excluded.

In addition, such a configuration is particularly advantageous since the internal combustion engine and / or the fuel cell does not have to be arranged at the position of a drive train or the like, but can be arranged in a more flexible and thus more targeted manner in the work machine.

Furthermore, the electric drive structure can have a battery for storing electrical energy in order to supply the first and second electrical drives with electrical energy.

According to such a configuration, not only a hybrid configuration can be implemented, but a purely electrically driven work machine can be achieved which manages without internal combustion engines and / or fuel cells provided on the work machine. Such a work machine is then charged in a stationary manner at a charging station and manages without fuel cells and / or internal combustion engines on the work machine itself.

It is also possible that both an internal combustion engine and / or a fuel cell and a battery are provided in the electric drive structure for the work machine.

According to such a refinement, it is possible for larger devices to initially carry out shorter activities fully electrically, whereas the fuel cell and / or the internal combustion engine continuously produce energy and also make it available. This electrical energy can then be used for the electrical drives, e.g. after the battery has been drained.

Furthermore, the electric drive structure can be designed such that the electrical energy generated by the internal combustion engine and / or the fuel cell and / or the electrical energy stored by the battery supplies the third and / or fourth electrical drive with electrical energy.

According to such an embodiment, each of the electrical drives can be supplied with electrical energy by a central element as an electrical energy source. This ensures a simple, inexpensive and flexible configuration of the electric drive structure for a work machine.

With a view to the above embodiments, an electric drive structure can thus be implemented which, for example, “only” has one battery in order to supply the electric drives with energy. In addition, it is conceivable that a fuel cell and / or a diesel generator alone are provided, which generate electrical energy via a generator in order to supply the electrical drives with energy. In addition, configurations are possible in which one or more fuel cells and / or a diesel generator and a battery are provided in order to generate energy and store it in the work machine.

Furthermore, the electric drive structure can have a control unit which is configured to detect a load on the first and second electric drive in order to at least partially transfer the drive torque via the clutch from a less loaded of the first and second electric drives to the most heavily loaded of the first and second electric drives switch on.

According to such an embodiment, an assisting power, that is to say a torque of a less loaded electric drive, can be transmitted from one axle to a more heavily loaded electric drive on a further axle of the work machine. It is thus possible to make the electric drives more compact, smaller and thus more cost-effective. In addition, an efficient transmission of propulsion between the front axle and the rear axle of the work machine can be ensured. The risk of digging into the ground in adverse soil conditions can also be prevented and the crop can also be less stressed by the working machine.

In addition, the control unit can be designed in such a way that it detects a load on the third electric drive and / or fourth electric drive in order to use the clutch and the mechanical coupling to control the drive torque of at least one less loaded of the first electric drive, the second electric drive, the third to connect the electric drive and / or the fourth electric drive at least partially to the heavily loaded or the heavily loaded of the first and second electric drive and the third and / or fourth electric drive.

According to such an embodiment, a particularly flexible and situation-appropriate adaptable electric drive structure can be generated. This enables electrical drives that are not or only slightly loaded to support more torque-intensive activities, for example with the electrical drives responsible for driving (first electric drive and second electric drive). On the other hand, it is also possible, in the case of torque-intensive activities on the PTO shaft that transmit a torque, for example to other equipment such as sugar beet harvesters, conveyor belts or the like, that the electric drives provided for the actual driving operation (i.e. the first and second electric drives) also support.

Correspondingly, the respective electric drives can be made more compact and more cost-effective, since they have to generate less torque independently as a single electric drive. This means that, for example, electrical drives provided for the propulsive power can be connected to highly loaded electrical drives for auxiliary drives, that is, the third and / or fourth electrical drives provided on power take-off shafts.

It is preferred here that the control unit is designed in such a way that it can perform the detection automatically and the connection manually or automatically.

According to such an embodiment, it is possible that less loaded electrical drives support higher loaded electrical drives via the clutch and, due to the automatic connection and detection, this can be done without further action by an operator of the machine.

Alternatively, with manual activation, an operator can anticipate a torque-intensive load on the electric drive structure and adjust and control the load distribution accordingly, so that no further adjustments are necessary during the torque-intensive activity.

Several, preferably all, of the first to fourth electrical drives can be configured to be able to recuperate braking energy in order to recover the braking energy.

In this way, for example, the battery can be charged during operation, thereby extending the range of the electric drive structure for a work machine.

Figure list

• 1: Eine schematische Darstellung einer Elektroantriebsstruktur gemäß einer ersten Ausführungsform.
• 2: Eine schematische Darstellung der Elektroantriebsstruktur gemäß einer zweiten Ausführungsform.
• 3: Eine schematische Querschnittsdarstellung der Elektroantriebsstruktur gemäß einer dritten Ausführungsform.
• 4: Eine schematische Darstellung der Elektroantriebsstruktur gemäß einer vierten Ausführungsform.

An electric drive structure for a work machine according to an exemplary embodiment is shown below with reference to schematic drawings. Such electric drive structures are used, for example, to generate propulsion and to drive auxiliary drives, for example on power take-offs. Show it:

• 1 : A schematic representation of an electric drive structure according to a first embodiment.
• 2 : A schematic representation of the electric drive structure according to a second embodiment.
• 3 : A schematic cross-sectional representation of the electric drive structure according to a third embodiment.
• 4th : A schematic representation of the electric drive structure according to a fourth embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the 1 The shown first embodiment of an electric drive structure relates to an electric drive structure for a work machine. This is preferably a tractor, but it is also possible that it is further agricultural, forestry, municipal or construction machinery, such as, for example, sugar beet harvesters, combine harvesters, wheel loaders or forestry vehicles. However, this list is not limiting.

The first embodiment has a front axle 2 with two front wheels 4th and a rear axle 3 with two rear wheels 5 on. Furthermore, it is also conceivable that further axes are provided so that, for example, work machines with three, four or more drive axes result.

The electric drive structure according to the first embodiment of FIG 1 also includes a first electric drive 6th to generate a drive torque. That first electric drive 6th drives the front wheels 4th at. It also includes electric drive structure of 1 a second electric drive 7th , which is also designed to generate a drive torque. This drive torque of the second electric drive 7th drives the rear wheels 5 at. Depending on requirements, the first and second electric drive 6th , 7th be identical or different powerful electric motors.

The electric drive structure of 1 a drive structure ready, which has an electric drive on the respective axles 2 , 3 of the working machine. The axes must accordingly 2 , 3 not be connected to a drivetrain to the front wheels 4th and rear wheels 5 to be able to drive the work machine. In other words, the first and second electric drives 6th , 7th are directly on the axle or at least close to the front or rear axle 2 , 3 arranged.

In the present invention, the electric drive can be understood as an electric motor gear unit with associated power electronics.

In other words, an electric drive described herein is able to independently generate a certain torque, which in turn is used to drive, for example, the wheels of the work machine. As described below, however, the electric drives described herein can also be suitable for driving a power take-off shaft.

The electric drives 6th , 7th according to the first embodiment are from an electrical power source 1 supplied with electrical power. This electrical power, which from electrical energy source 1 is provided, is in turn used to generate, for example, drive torque, in the first or second electric drive 6th , 7th used.

As mentioned above, this is the first electric drive 6th on the front axle 2 arranged, whereas the second electric drive 7th on the rear axle 3 is arranged.

It is possible that the first electric drive 6th and the second electric drive 7th are arranged or flanged directly to the front axle or rear axle in order to reduce transmission losses.

As an alternative to this, however, it is possible, for example, in an embodiment with sprung axles in a work machine, that the first electric drive 6th and the second electric drive 7th with cardan shafts, in particular cardan shafts, are connected to the front axle or rear axle and are not attached directly to the axle. This is the first electric drive 6th and the second electric drive 7th installed in the vehicle frame. The protection of the electric drives can be increased accordingly.

This source of electrical energy 1 can for example be designed in the form of an internal combustion engine, in particular a diesel engine with a generator for generating electricity. This means that the diesel engine also generates a torque through the combustion of fuel, which drives an electricity generator, which then serves as an electrical energy source 1 the electric drives, which are close to the place of action, here, for example the front axle 2 and the rear axle 3 , are provided, drives.

Alternatively, a fuel cell can be used as the source of electrical energy 1 and thus serve to generate electrical energy. Here the transmission takes place from the electrical energy source 1 to the electric drives via an electric cable 16 to the respective electric drives 6th , 7th . As an alternative or in addition to the internal combustion engine or the fuel cell described above, a battery (not shown) can be used as the electrical energy source 1 serve and thus be designed to store electrical energy in order to supply the electrical drives with electrical energy. Accordingly, not only a hybrid configuration, but a purely electrically operated electric drive structure can be implemented.

As in 1 Also shown in the electric drive structure according to the first embodiment is a clutch between the first electric drive 6th and the second electric drive 7th intended. This clutch enables the drive torque of the first and second electric drive 6th , 7th variable between the front axle 2 and the rear axle 3 can be transferred.

In other words, the drive torques generated by the first electric drive 6th and the second electric drive 7th can be generated on the respective axes via the first and second electric drive 6th , 7th be activated.

This means that the coupling enables such a variable configuration that drive torques of the respective first and second electric drives 6th , 7th to the respective necessary places of action, here for example on the front axle 2 or the rear axle 3 can be transferred. That is, the coupling enables a variable connection of the first electric drive 6th and the second electric drive 7th so that a torque or power can be transmitted for support.

This is particularly advantageous because, on the one hand, electrical drives are provided that are independent of the axis, and thus the electrical drives 6th , 7th are provided as close as possible to the target place of action, here on the traction drive, and thus transmission losses can be prevented. On the other hand, the electric drives 6th , 7th be designed to be compact and inexpensive and at the same time be sufficiently powerful or provide sufficient power to provide sufficient torque even for heavy pulling and pushing work, such as plowing, backing wood or front loading work, as well as in adverse soil conditions and an unfavorable weight distribution.

This means that the coupling enables a variable torque or power transmission of the electric drives within the present electric drive structure.

The actual design of the front axle 2 and rear axle 3 is not relevant here. Independent wheel suspensions or rigid axles etc. can be provided here.

Moreover, in the electric drive structure according to a first embodiment, a transmission can optionally also be used 9 be provided.

This gear 9 can be attached to the coupling between the first electric drive 6th and the second electric drive 7th be provided. Thus, the drive torque of the first and second electric drive 6th , 7th between the front axle 2 and the rear axle 3 not only transmitted, but also translated.

This is advantageous, for example, if only part of the drive power, that is to say the drive torque of the first electric drive 6th on the front axle 2 to drive the front wheels 4th is used and the remaining part of the drive torque via the clutch to the rear wheels 5 is transmitted and thereby different tire diameters of the front wheels 4th and rear wheels 5 are present. This can make further translations unnecessary and thus a simpler structure can be achieved.

Thus, the drive torque of the first electric drive 6th or the second electric drive 7th not only transmitted, but also translated.

2 Fig. 10 illustrates an electric drive structure according to a second embodiment.

In all of the embodiments described herein, elements provided with the same reference numbers designate the same or similar elements.

In addition to the in 1 illustrated first embodiment, the second embodiment according to 2 also a third electric drive 10 to generate a drive torque. This third electric drive 10 , is to be understood as a power take-off and is designed to have a first PTO shaft 11 to drive the working machine. In addition, the electric drive structure according to the second embodiment of FIG 2 also a fourth electric drive 12th to generate a further drive torque. This fourth electric drive 12th is designed a second PTO 13th to drive.

The first and second power take-off shafts 11 , 13th near the front axle 2 and the rear axle 3 of the working machines can be provided and thus deliver a torque to further equipment and connectable devices at the front or rear of the working machine.

An example of this would be the connection of a potato harvester. The torque of the third or fourth electric drive can be used here 10 , 12th to the outside of the connected potato harvester via one of the PTO shafts 11 , 13th be transmitted in order to drive conveyor belts on this equipment, for example. the Position of the PTO shafts 11 , 13th on the work machine is not limited to this.

The electric power source described with reference to the first embodiment 1 is also designed to have additional electrical lines 16 , the third electric drive 10 and the fourth electric drive 12th also to be supplied with electrical energy. That means the source of electrical energy 1 serves as a global power supply for the first to fourth electric drives 6th , 7th , 10 , 12th the second embodiment, which in turn provides drive torques for the power take-offs, i.e. the first and second PTO shafts 11 , 13th and / or for driving, i.e. driving the front axle 3 and the rear axle 4th and the associated front wheels 4th and rear wheels 5 generated.

3 Figure 3 illustrates a further, third embodiment. In addition to the arrangements according to the first and second embodiment, in FIG 3 illustrated third embodiment of the third and fourth electric drive 10 , 12th with the variable clutch 8th directly by means of a switchable gear arrangement 14th mechanically coupled.

This allows the drive torques of the electric drives 6th , 7th , 10 , 12th between the first electric drive 6th , the second electric drive 7th , the third electric drive 10 and / or the fourth electric drive 12th can be transmitted variably.

That is, if the third and / or fourth electric drive is switched on 10 , 12th , for example for driving, it is possible to switch on the drive torques of the electric drives variably among each other. This is where the third and fourth electric drives are connected 10 , 12th with the clutch 8th about the gear arrangement 14th in an activated state. The coupling 8th can include the first and / or second electric drive 6th , 7th variable to gear arrangement 14th switch on. Furthermore, the clutch 8th among other things, without the involvement of the gear arrangement 14th the first and second electric drive 6th , 7th connect variably for the drive torque exchange.

Is the gear arrangement 14th not switched on, there is no drive torque transmission from the third and fourth electric drives 10 , 12th on the clutch 8th and thus to the first or second electric drive 6th , 7th the electric drive structure according to the third embodiment.

A rigid coupling is available as an option 19th be provided, which allows only one of the third and fourth electric drive 10 , 12th the drive torque on the gear assembly 14th transmits.

Operating modes can thus be generated in which, for example, the fourth electric drive 12th the second PTO 13th drives independently of the other electric drives and, for example, the third electric drive 10 its drive torque for driving by the first and second electric drive 6th , 7th provides. Thus, the second PTO 13th by the fourth electric drive 12th are driven and the third electric drive, which is not required in this example 10 , the driving operation of the first electric drive 6th and the second electric drive 7th via the closed rigid coupling 19th on the first PTO 11 who have favourited gear assembly 14th and the clutch 8th support. The rigid coupling 19th on the second PTO 13th , which is the fourth electric drive 12th with the gear arrangement 14th connects, is open in this case, so that no coupling of the fourth electric drive 12th with the gear arrangement 14th he follows.

In addition, it is also possible that both drive torques of the third electric drive 10 and the fourth electric drive 12th via the closed rigid couplings 19th with the gear arrangement 14th are connected and thus at least partially or completely the drive torque that can be generated by them via the clutch and the gear arrangement 14th to the first and second electric drives provided for the travel drive 6th , 7th transfer.

Conversely, it is also possible that the first and second electric drives 6th , 7th your drive torque via the clutch 8th who have favourited gear assembly 14th and at least one closed rigid coupling 19th to the third and / or fourth electric drive 10 , 12th transferring support. This means that increased power can be achieved on the third and / or fourth electric drive 10 , 12th to provide.

4th Fig. 11 illustrates a further, fourth embodiment. In contrast to the first to third embodiments described above, in the fourth embodiment the first electric drive 6th two electric motors 15th on. In addition, the second electric drive 7th two electric motors 15th on.

Here is each of the electric motors 15th the front axle 2 designed a front wheel 4th individually to drive and each of the electric motors of the rear axle 3 is designed a rear wheel 5 to drive individually.

In other words, by the electric motors 15th a single wheel drive can be generated.

Here the electric motors 15th , which can also be understood as wheel hub motors, also have a planetary gear for torque-speed adjustment.

As in 4th shown, each of the wheels is driven individually. Here, each of the wheels is via a wheel hub drive coupling 17th and one on each axle, i.e. the front axle 2 and the rear axle 3 , provided angular gear 18th connected to the clutch. As a rule, a differential gear is also necessary here. According to such an embodiment, the two electric motors 15th on the front axle 2 and the two electric motors 15th on the rear axle 3 individually transmit their drive torque to at least one of the wheels and thus not only individually drive a single wheel, but also support one or at least one additional wheel in driving when there is less need.

Moreover, it is due to the arrangement of the clutch, the gear arrangement 14th and the rigid couplings 19th possible that the single wheel drives by the electric motors 15th to support the third and fourth electric drives 10 , 12th and thus to drive the first and second PTO shafts 11 , 13th contribute and vice versa.

Each of the first to fourth embodiments described above may further include a control unit.

Such a control unit is designed to place a load on at least the first and second electric drive 6th , 7th to detect and via the coupling of the drive torque from the less loaded of the first and second electric drive 6th , 7th on the highest loads of the first and second electric drive 6th , 7th to be switched on at least partially.

In addition, however, it is also possible for the control unit to be designed so that it also has a load on the third electric drive 10 and / or fourth electric drive 12th detected to via the clutch and the mechanical coupling via the gear arrangement 14th the drive torque of at least one less loaded person of the first electric drive 6th , the second electric drive 7th , the third electric drive 10 and the fourth electric drive 12th on the highest loads of the first and second electric drive 6th , 7th as well as the third and fourth electric drive 10 , 12th at least partially activates (cf. 2 until 4th ).

In this case, the acquisition takes place, for example, via torque sensors in the electric drives 6th , 7th , 10 , 12th are provided and configured, one on the respective electric drives 6th , 7th , 10 , 12th to detect the applied torque. However, other types of sensors and methods for detecting the load acting on the respective electric drives are also possible. For example, the torque can be determined indirectly via the necessary electrical power. Manual control of the “mixture” via the control unit by the vehicle driver is also conceivable.

In this way it is possible to determine the acting torques on the respective electric drives 6th , 7th , 10 , 12th for driving operation or the power take-offs and to record overloads on the electrical drives 6th , 7th , 10 , 12th to be avoided, since to support the drive torque further, less loaded electric drives can be switched on or switched on to the most heavily loaded electric drive. Accordingly, it is possible according to the present invention, the respective electric drives 6th , 7th , 10 , 12th for the driving operation and the operation of power take-offs to be made more compact and less powerful while still enabling a high level of operational safety and reliability.

In this case, it is particularly preferable for the detection, for example by torque sensors, and the connection via the clutch, the wheel hub drive clutch, to take place 18th and / or the rigid coupling 19th automatically.

Here, for example, actuators can be provided, which ensure a corresponding interconnection or opening and closing of the respective clutches and correspondingly guide the drive torques through the machine to the respective point of action. Furthermore, due to these actuators, it is possible to have couplings on the respective electric drives 6th , 7th , 10 , 12th to open when not required and not to operate them or to operate them individually.

However, the present invention is not limited to such actuators and a control unit. It is also possible, for example, for the respective electrical drives and clutches etc. to have their own sub-control units which record the power and control the variable torque transmission within the machine in a decentralized manner.

As already described at the beginning, the second power take-off shaft, for example 13th by operating the fourth electric drive 12th can be operated independently of the other electrical drives. Meanwhile, for example, the third electric drive 10 , the drive torque it generates for the driving mode, the front wheels 4th and rear wheels 5 provide.

List of reference symbols

1

electrical energy source

2

Front axle

3

Rear axle

4th

Front wheel

5

Rear wheel

6th

first electric drive

7th

second electric drive

8th

variable clutch

9

transmission

10

third electric drive

11

first PTO

12th

fourth electric drive

13th

second PTO

14th

Gear arrangement

15th

Electric motor

16

Electric line

17th

Wheel hub drive coupling

18th

Angular gear

19th

Rigid coupling

Claims (15)

Electric drive structure for a work machine, in particular for a tractor, comprising: a front axle (2) with two front wheels (4); a rear axle (3) with two rear wheels (5); a first electric drive (6) for generating a drive torque for driving the front wheels (4); a second electric drive (7) for generating a drive torque for driving the rear wheels (5); and a coupling between the first electric drive (6) and the second electric drive (7), via which the drive torque of the first and second electric drive (6, 7) can be variably transmitted between the front axle (2) and the rear axle (3) . Electric drive structure according to Claim 1 , wherein the first electric drive (6) is arranged on the front axle (2), and wherein the second electric drive (7) is arranged on the rear axle (3). Electric drive structure according to Claim 1 or 2 , wherein the first electric drive (6) is designed to drive the front axle (2) and thereby the front wheels (4), and wherein the second electric drive (7) is designed to drive the rear axle (3) and thereby the rear wheels (5) to drive. Electric drive structure according to Claim 1 or 2 wherein the first electric drive (6) has two electric motors (15), each of the electric motors (15) of the front axle (2) being designed to drive a front wheel (4) individually, and the second electric drive (7) having two electric motors (15), each of the electric motors (15) of the rear axle (3) being designed to drive a rear wheel (5) individually. Electric drive structure according to one of the preceding claims, wherein a gear (9) is further provided between the first electric drive (6) and the second electric drive (7), via which the drive torque of the first and second electric drive (6, 7) between the Front axle (4) and the rear axle (3) can be transmitted and translated. Electric drive structure according to one of the preceding claims, wherein the electric drive structure further comprises a third electric drive (10) for generating a drive torque for driving a first power take-off shaft (11). Electric drive structure according to one of the preceding claims, wherein the electric drive structure further comprises a fourth electric drive (12) for generating a drive torque for driving a second power take-off shaft (13). Electric drive structure according to Claim 6 or 7th , wherein the third and / or fourth electric drive (10, 12) is mechanically coupled directly or indirectly to the coupling, so that the drive torques of the electric drives between the first electric drive (6), the second electric drive (7), the third electric drive (10) and / or the fourth electric drive (12) can be transmitted variably. Electric drive structure according to Claim 8 , the mechanical coupling taking place via a switchable gear arrangement (14). Electric drive structure according to one of the preceding claims, wherein the electron drive structure has an internal combustion engine, in particular a diesel engine, and / or a fuel cell for generating electrical energy in order to supply the first and second electrical drive (6, 7) with electrical energy. Electric drive structure according to one of the preceding claims, wherein the electron drive structure has a battery for storing electrical energy in order to supply the first and second electrical drives (6, 7) with electrical energy. Electric drive structure according to Claim 10 or 11 , wherein the electron drive structure is designed such that the electrical energy generated by the internal combustion engine and / or the fuel cell and / or the electrical energy stored by the battery also supplies the third and / or fourth electrical drive (10, 12) with electrical energy. Electric drive structure according to one of the preceding claims, wherein the electric drive structure further comprises a control unit which is designed to detect a load on the first and second electric drive (6, 7) in order to use the coupling to reduce the drive torque of a less loaded one of the first and second electric drives To connect the drive (6, 7) at least partially to the maximum load of the first and second electric drive (6, 7). Electric drive structure according to Claim 13 , wherein the control unit is designed such that it also detects a load on the third electric drive (10) and / or fourth electric drive (12) in order to use the clutch and the mechanical coupling to control the drive torque of at least one less loaded of the first electric drive (6), the second electric drive (7), the third electric drive (10) and / or the fourth electric drive (12) to the heavily loaded or heavily loaded of the first and second electric drive and the third and / or fourth electric drive (10, 12) to be switched on at least partially. Electric drive structure according to Claim 13 or 14th , wherein the control unit is designed to carry out the detection automatically and the connection manually or automatically.

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