WO2023139228A1

WO2023139228A1 - Drive train for a work machine

Info

Publication number: WO2023139228A1
Application number: PCT/EP2023/051404
Authority: WO
Inventors: Thomas Oberbuchner
Original assignee: Zf Friedrichshafen Ag
Priority date: 2022-01-24
Filing date: 2023-01-20
Publication date: 2023-07-27
Also published as: DE102022200713B4; DE102022200713A1

Abstract

An electric drive train (10) for a work machine having two electric motors (EM1, EM2) each with an associated motor shaft (12, 14) is provided. The drive train (10) has a transmission (16) with one output shaft (18) and the motor shafts (12, 14) as input shafts. The transmission (16) has a first double shift element (S1), a second double shift element (S2) and a third shift element (S3). The first input shaft (22) is mechanically operatively connected to the output shaft (18) with a first transmission ratio in a first shift position of the first double shift element (S1) and with a third transmission ratio in a second shift position. The second input shaft (24) is mechanically operatively connected to the output shaft (18) with a second transmission ratio in a first shift position of the second double shift element (S2) and with a fourth transmission ratio in a second shift position. The first input shaft (22) is operatively connected to the second input shaft (24) by means of the third shift element (S3). In addition, a method and a work machine are provided.

Description

Drive train for a working machine

technical field

The present invention relates to a drive train for a work machine with two electric motors. In addition, the invention relates to a method for operating such a drive train and a work machine.

State of the art

Transmission systems for work machines with internal combustion engines are often very complex and expensive. For example, a hydrostatic power-split transmission can be provided in order to be able to provide a continuously variable transmission. Due to the power split, both a drive power and a power take-off can be provided by a single internal combustion engine. Transmissions adapted to internal combustion engines cannot generally be used for electric powertrains, since electric motors and internal combustion engines have very different torque-speed characteristics.

The diverse range of uses of a mobile working machine also means that a very large total gear spread of often more than 100 is necessary and sometimes even total gear spreads of up to 1000. In principle, a continuously variable electric motor can map this spread without a gearbox, but only with noticeable limitations in terms of performance and efficiency. For this reason, it is known to also use gears for electrically driven machines. Transmissions for fully electrified vehicle drives of work machines can be designed to be switchable with or without load interruption. Concepts with a change of driving range without load interruption are clearly superior to those with a change of driving range with load interruption in practical use, at least with high tractive forces in combination with slow speeds. Traction can continue to be provided without an interruption in the load force, even when changing the driving range. As a rule, wet multi-disk friction clutches are used as shifting elements that can be shifted without load interruption. However, they generate high friction losses during a load shift and unwanted drag torques in the open state.

DE 10 2019 202 994 A1 describes a drive unit for an electric vehicle with an electric machine and a three-speed manual transmission.

DE 10 2019 214 986 A1 describes a drive axle of an electric vehicle with a first electric machine and a second electric machine, with the second electric machine being able to be switched on as an additional drive if required.

Presentation of the invention

A first aspect of the invention relates to an electric drive train for a work machine. A drive train can, for example, provide a drive power and optionally also a power take-off. The drive power can be used to drive the working machine. An attachment of the work machine, such as an adjustable shovel, can be supplied with power using the power tap. The working machine can be used as an agricultural machine, e.g. B. be designed as a tractor, as a construction machine or as a special vehicle. An example of a working machine is a wheel loader in which the respective wheels can be driven by the drive power and a shovel can be raised and lowered as an attachment.

The drive train has a first electric motor with a first motor shaft. For example, a first output of the working machine can be provided at the first motor shaft. A motor shaft can be designed as an output shaft of an electric motor. The first motor shaft can, for example, be connected to a rotor of the first electric motor or be formed by it. Furthermore, the drive train has a second electric motor with a second motor shaft. For example, a second output of the work machine can be provided at the second motor shaft. The second motor shaft can, for example, be connected to a rotor of the be connected to the second electric motor or be formed by this. The designation as the second motor shaft is used only for assignment to the second electric motor. The second electric motor has, for example, no more than one motor shaft. The two electric motors can be designed as traction motors.

The drive train has a shiftable transmission with an output shaft. At the output shaft, for example, a mileage can be provided by the drive train. The output shaft can be designed, for example, as a driving axis of the working machine. The output shaft can transmit drive power to an output of the work machine, for example respective wheels or chains of the work machine. By driving the output shaft, the working machine can be moved over a ground, for example. The working machine can also have several drive axles, which are driven jointly or separately. The output shaft can, for example, be rotatably mounted on the working machine. By rotating the output shaft, for example, a travel movement of the working machine can be brought about.

For example, wheels can be attached to respective ends of respective drive axles, by means of which a drive torque can be transmitted to the ground. With these wheels, the working machine can stand on a surface. In addition, the work machine can have respective non-driven axles.

The transmission can provide different translations between the electric motors and the output shaft. The gear ratio can be changed by shifting the transmission. For example, different driving areas can be provided. The transmission can be designed to provide several shiftable gears. The transmission can have respective shifting elements for this. A ratio can be a fixed ratio between one or more input variables and an output variable.

The first motor shaft forms a first input shaft of the transmission. For this purpose, the first motor shaft can be designed in one piece with the first input shaft or can be permanently connected in a non-rotatable manner in some other way. But the first motor shaft can also be switchable and rotatably connected to the first input shaft, for example if certain double switching elements of the transmission do not have a neutral position. The second motor shaft forms a second input shaft of the transmission. For this purpose, the second motor shaft can be designed in one piece with the second input shaft or can be permanently connected in a non-rotatable manner in some other way. However, the second motor shaft can also be connectable in a switchable, non-rotatable manner to the first input shaft, for example if certain double shifting elements of the transmission do not have a neutral position. A variable to be translated, such as a torque, can be introduced into the transmission at an input shaft. Respective translated variables, such as a torque or a combination of several torques, can be output at the output shaft.

The transmission has a first double shifting element, a second double shifting element and a third shifting element. Different driving ranges can be provided, for example, by switching these switching elements. A double switching element is a special form of switching element. Correspondingly, the transmission does not additionally have a first or second shifting element, for example, which differ from the first and second double shifting element. The numbering of the switching elements or double switching element is used here for their clear assignment. The first double switching element can be arranged coaxially with the first input shaft, for example. The second double switching element can, for example, be arranged coaxially with the second input shaft. The third switching element can be arranged, for example, coaxially with the first input shaft or the second input shaft. A compact and simple construction results. Alternatively, the double switching elements can also be arranged coaxially with the output shaft, for example.

A switchable connection can enable torque transmission between two elements in one state, for example by means of a rigid coupling, and essentially interrupt this torque transmission in another state. A corresponding switching element can be provided for this between the two elements. A switching element can, for example, be designed with a friction fit or a form fit. An example of a frictional shifting element is a multi-plate clutch. An example of a form-fitting shifting element is a claw clutch. A switching element can be closed by actuation. For example, a switching element can be actuated with oil pressure in order to enable torque transmission between two elements. A switching element can be biased with respect to its open state. For example, when an oil pressure is lost, a switching element can automatically move into its open state in order to essentially interrupt the torque transmission between two elements.

A double shifting element can be designed as a frictional or form-fitting shifting element. For example, the double shifting element can be designed as a claw clutch. A double switching element can have at least two switching positions. A double switching element can be adjustable between a first switching position and a second switching position. In the first shift position of the double shift element, a different non-rotatable connection can be provided than in the second shift position of the double shift element. Optionally, the double switching element can have a third switching position in which there is no non-rotatable connection between two elements. The third shift position can be a neutral position. A double switching element is compact and inexpensive.

In addition, a double switching element can be easily adjusted. For example, in the case of a double switching element, one actuator can be sufficient for adjustment, while two individual switching elements can require two actuators.

In a first shift position of the first double shift element, the first input shaft is mechanically operatively connected to the output shaft with a first gear ratio. In a second shift position of the first double shift element, the first input shaft is mechanically operatively connected to the output shaft with a third gear ratio. In a first shift position of the second double shift element, the second input shaft is mechanically operatively connected to the output shaft with a second gear ratio. The second input shaft is mechanically operatively connected to the output shaft in a second shift position of the second double shift element with a fourth gear ratio. In this way, four different driving ranges can be made available. In addition, the two can Electric motors support each other when driving the work machine in many driving ranges. This allows the drive train to work very efficiently. The two electric motors can, for example, each be designed for a lower drive power than the maximum total required by the working machine. The different translations can be of different sizes.

The first input shaft can be mechanically operatively connected to the second input shaft by means of the third shifting element. As a result, the electric motors can drive the work machine together in four driving ranges, for example also in the highest driving range. In addition, a change of driving range without interruption of the train can be made possible in this way, even if the three aforementioned shifting elements are designed in a form-fitting manner. Intermediate driving areas can be used for this, for example. The drive train is correspondingly very powerful and efficient. In addition, a high degree of flexibility in torque distribution and, alternatively or additionally, load distribution between the two electric motors is possible.

The input shafts can be arranged parallel to one another, for example. The output shaft can be arranged parallel to the first input shaft and alternatively or additionally to the second input shaft. The output shaft can be arranged radially between the first input shaft and the second input shaft. The respective translations can be provided, for example, by spur gears and alternatively or additionally by planetary gear sets. The first input shaft may have a different parallel spacing to the output shaft than the second input shaft. As a result, for example, a high gear spread can be achieved.

The transmission and also the drive train as a whole can, for example, be free of shifting elements other than those mentioned here. The transmission and also the drive train can also, for example, be free of other moving elements than those described here, such as shafts and spur gear stages. The drive train can have an energy source for operating the two electric motors. For example, the drive train can have a battery which is designed to provide electrical energy for the two electric motors. An electric motor can be designed to convert electrical energy into mechanical energy. Optionally, an electric motor can also be designed for recuperation. An electric motor can be designed, for example, as a synchronous motor or an asynchronous motor.

If two elements are mechanically operatively connected, they are directly or indirectly coupled to one another in such a way that a movement of one element causes a reaction in the other element. For example, a mechanical operative connection can be provided by a form-fitting or friction-fitting connection. For example, the mechanical operative connection can correspond to meshing of corresponding teeth of two elements. Further elements, for example one or more spur gear stages, can be provided between the elements. A permanent non-rotatable connection between two elements is understood to mean a connection in which the two elements are essentially rigidly coupled to one another in all intended states of the transmission. This also includes a frictional connection, in which intentional or unintentional slippage can occur. Permanently non-rotatably connected elements can be in the form of individual components non-rotatably connected to one another or also in one piece. A connection of two elements via a further element can mean that this further element is involved in an indirect effective connection of the two elements. For example, this further element can be arranged in the power flow between these two elements. A connection of two elements via two or more elements can mean that these further elements are all involved in an indirect operative connection of the two elements.

In a further embodiment of the drive train, it can be provided that the transmission has a first spur gear stage, a second spur gear stage, a third spur gear stage and a fourth spur gear stage. A spur gear is a cost-effective and very efficient design of a mechanical operative connection with a translation. A spur gear stage can, for example, be designed in one stage or in multiple stages. A single-stage spur gear stage can have, for example, two gears meshing with one another. A two-stage spur gear stage can have, for example, three gears meshing with one another. The gears of a spur gear stage can be designed as spur gears. The respective idler gears of a spur gear stage can be connected in a torque-proof manner to one of the input shafts, for example via one of the two double switching elements. The respective fixed gears of a spur gear stage can, for example, be permanently connected to the output shaft in a rotationally fixed manner.

In the first shift position of the first double shift element, the first input shaft can be mechanically operatively connected to the output shaft via the first spur gear stage. In the second shift position of the first double shift element, the first input shaft can be mechanically operatively connected to the output shaft via the third spur gear stage. The second input shaft can be mechanically operatively connected to the output shaft in the first shift position of the second double shift element with the third spur gear stage. The second input shaft can be mechanically operatively connected to the output shaft in the second shift position of the second double shift element with the fourth spur gear stage. A simple, inexpensive and efficient drive train results.

In a further embodiment of the drive train, it can be provided that the transmission has a fifth spur gear stage. The transmission can be free of further spur gear stages than those described here. The first input shaft can be mechanically operatively connected to the second input shaft by means of the third shifting element via the fifth spur gear stage. A cost-effective and efficient design for a drive train with an uninterrupted change of driving range can result.

In a further embodiment of the drive train, it can be provided that a spur gear of the fifth spur gear stage is rotatably mounted on the output shaft. As a result, this spur gear can be stored easily and in a space-saving manner. For example, the output shaft can move axially via the two double shifting elements and, alternatively or additionally, the first to fourth spur gear stages extend out. Respective loads on the fifth spur gear can be well supported on the output shaft.

In a further embodiment of the drive train, it can be provided that the third shifting element is mounted on one of the two input shafts. As a result, the integration of the third switching element is simple and space-saving. For example, the third switching element can be arranged coaxially with that of the two input shafts on which the third switching element is mounted.

In a further embodiment of the drive train, provision can be made for the third shifting element to be in the form of a positive-locking shifting element. Alternatively or additionally, it can be provided that the first double switching element is designed as a form-fitting switching element. Alternatively or additionally, it can be provided that the second double switching element is designed as a form-fitting switching element. For example, each of the aforementioned shifting elements of the transmission can be designed as a positive-locking shifting element. Compared to a frictional shift element, a positive shift element can be more efficient and robust. With a form-fit shifting element, it is not easy to change driving ranges without any interruption in traction. Because the first input shaft can be mechanically connected to the second input shaft by means of the third shifting element, however, it is also possible to change between, for example, four driving ranges without interrupting traction using only positive-locking shifting elements. In comparison to a friction-locking shifting element, no active control of form-locking shifting elements is necessary when they are actuated. Respective switching positions of form-fitting switching elements can essentially only be adjusted with respect to their end position, without adjustment dynamics having to be taken into account and controlled. Only a small requirement is placed on the shift actuators. Likewise, no complex software is required to control the actuation.

In a further embodiment of the drive train, provision can be made for the first double shifting element to have a neutral position in which torque is transmitted from the first input shaft to the output shaft via the first double switching element is interrupted. Torque can still be transmitted from the first input shaft to the output shaft via the third shifting element, the second input shaft and the second double shifting element, for example when the second double shifting element is not in its neutral position. Alternatively or additionally, it can be provided that the second double shifting element has a neutral position in which a torque transmission from the second input shaft to the output shaft via the second double shifting element is interrupted. Torque can still be transmitted from the second input shaft to the output shaft via the third shifting element, the first input shaft and the first double shifting element, for example when the first double shifting element is not in its neutral position. An idle can be provided by the neutral positions. In addition, respective intermediate driving ranges can be provided by the respective neutral position. Intermediate driving areas can be used to change driving areas without any interruption in traction.

In a further embodiment of the drive train, it can be provided that the first double shifting element is mounted on the first input shaft. Alternatively or additionally, provision can be made for the second double shifting element to be mounted on the second input shaft. As a result, the integration of the first double switching element or the second double switching element is simple and space-saving. For example, the first or second double shifting element can be arranged coaxially with that one of the two input shafts on which the third shifting element is mounted.

In a further embodiment of the drive train, provision can be made for the first spur gear stage and the second spur gear stage to share a spur gear. The first spur gear stage and the second spur gear stage can share a spur gear, for example a first fixed gear permanently non-rotatably connected to the output shaft. Alternatively or additionally, it can be provided that the third spur gear stage and the fourth spur gear stage share a spur gear. The third spur gear stage and the fourth spur gear stage can share a spur gear, for example a second fixed gear permanently non-rotatably connected to the output shaft. Through this the gearbox is compact and inexpensive. Very few parts are required. With different parallel distances between the input shafts and the output shaft, a different translation can still be provided by the two spur gear stages, which use a spur gear jointly. Alternatively, the respective spur gears can also not use spur gears in common. For example, a fixed gear permanently non-rotatably connected to the output shaft can be provided for each spur gear stage. This makes the interpretation of the different translations particularly simple.

In a further embodiment of the drive train, it can be provided that the drive train has a fourth shifting element and a power take-off shaft. One of the two input shafts can be mechanically operatively connected to the PTO shaft by means of the fourth shifting element. The fourth switching element can, for example, also be designed in a form-fitting manner. It may then be necessary to select a specific driving range in order to be able to couple the PTO shaft by means of the fourth shifting element while driving.

Further spur gear stages can be provided between that one of the two input shafts which can be mechanically operatively connected to the power take-off shaft by means of the fourth shifting element, and the power take-off shaft. The drive train can be designed in such a way that the mechanical operative connection between the power take-off shaft and this input shaft can also be produced if respective

Double switching element are in their neutral position. As a result, it may be possible to independently provide driving power with one of the two electric motors and power tapping with the other of the two electric motors. In certain switching states, for example, the PTO shaft can be driven by one of the two electric motors and the output shaft independently by the other of the two electric motors. The drive train can also have a power take-off, by means of which different translations can be provided between this input shaft and the power take-off. By connecting the two input shafts through the third switching element, the PTO shaft can also be driven by both electric motors, for example when no drive is required. Then particularly high tap power can be provided. A ground PTO function can also be provided.

A second aspect relates to a method for operating the power train according to the first aspect. The respective advantages and further features can be found in the description of the first aspect, with configurations of the first aspect also forming configurations of the second aspect and vice versa. The method has a step of operating the drive train with one of the following four driving ranges. The method also has a step of changing the driving range from a current driving range to a desired driving range without an interruption in traction. The drive train can thus be operated in a particularly powerful and efficient manner. The driving range change without interruption of tractive force can take place by changing consecutive driving ranges.

In a first driving range, the third shift element is closed and the first double shift element is in its first shift position. The second double switching element can be in its neutral position. In a second driving range, the third shift element is closed and the second double shift element is in its first shift position. The first double switching element can be in its neutral position. In a third driving range, the third shift element is closed and the first double shift element is in its second shift position. The second double switching element can be in its neutral position. In a fourth driving range, the third shift element is closed and the second double shift element is in its second shift position. The first double switching element can be in its neutral position. The four driving ranges are particularly suitable for continuous operation of the drive train. The drive power can be provided by both electric motors. For example, the four driving ranges are used in a first mode without a connected PTO. The optional fourth switching element is open in the first mode. In certain driving ranges, the optional PTO shaft can be coupled in a second mode by means of the closed fourth shifting element. In a further embodiment of the drive train, it can be provided that the step of changing the driving range has at least one of the following steps. At the beginning of the driving range change and also before that, the two electric motors can be controlled in such a way that both electric motors jointly provide the drive power currently required.

The step of changing the driving range can include a step of controlling the power of the two electric motors, so that a primary motor of the two electric motors alone provides a required drive power in the current driving range. For example, a secondary motor of the two electric motors can be de-energized for this purpose. As a result, one of the two double switching elements and, alternatively or additionally, the third switching element can be load-free. The primary motor and secondary motor are each an assignment which results from the current and the desired driving range. Both electric motors can also be designed identically, for example. Depending on the driving range change, the first electric motor or the second electric motor can correspond to the primary motor. Likewise, depending on the change in driving range, the first electric motor or the second electric motor can correspond to the secondary motor.

The step of changing the driving range can include a step of opening the third shifting element. This opening of the third switching element can take place, for example, as soon as the primary motor provides the required drive power in the current driving range completely on its own. In this way, the required drive power can continue to be fully provided at the output shaft.

The step of changing the driving range may include a step of synchronizing a speed of the secondary motor with the desired driving range. This step can take place after opening the third switching element. For example, the speed of the secondary motor can be set in such a way that a double switching element that is directly connected to its motor shaft rotates at the same speed on both sides. For example, the speed of the secondary motor can be set so that the second double switching element on both sides with the same Speed rotates if the secondary motor corresponds to the second electric motor in the driving range change. For example, an output-side side of the second double shifting element can also be rotated via a spur gear for the desired driving range by the output shaft, which is further driven by the first electric motor. On the input side, the second input shaft can be rotated by the second electric motor at a corresponding speed, so that the output side of the second double shifting element and a drive of the second double shifting element rotate at the same speed.

The step of changing the driving range can include a step of engaging an intermediate driving range by shifting one of the two double shift elements from its neutral position to a different position. This step can be done after synchronizing the speed of the secondary motor of the two electric motors with the desired driving range. For example, this double shift element can be adjusted in such a way that the output side of the second double shift element, which is connected to the spur gear stage for the desired driving range, is non-rotatably connected to a corresponding input shaft. As a result, a form-fit double shift element can also be closed simply starting from its neutral position. For example, in the intermediate driving range, both electric motors can drive the output shaft, but are connected to the output shaft with different gear ratios. As a result, one of the two electric motors can be in an inefficient operating range, for example if both electric motors are of the same design.

The step of changing the driving range can be a step of controlling the power of the two electric motors, so that now the secondary motor alone provides the required drive power in the intermediate driving range. For example, the primary motor can be de-energized for this purpose. As a result, another of the two double switching elements and, alternatively or additionally, the third switching element can now be load-free.

The step of changing the driving range can include a step of shifting the other of the two double shift elements into its neutral position. This pretending into the neutral position can take place, for example, as soon as the secondary motor provides the required drive power in the current driving range completely on its own. This means that the primary motor can now be decoupled from the output shaft. Nevertheless, the required drive power can still be fully provided at the output shaft, now by the secondary motor.

The step of changing the driving range may include a step of synchronizing a speed of the primary motor with the desired driving range. This step can take place after the other of the two double switching elements has been moved into its neutral position. For example, a speed can be set on the second motor shaft which corresponds to a speed of the first motor shaft. As a result, the third switching element can be closed without a speed difference. As a result, a form-fitting third switching element can also be closed in a simple manner.

The step of changing the driving range can include a step of closing the third shifting element in order to change into the desired driving range. This step can be done after synchronizing the primary motor speed with the desired range of travel. Now the drive power in each of the four driving ranges can again be provided jointly by both electric motors. For example, both electric motors now drive the output shaft via one of the four spur gear stages, it being possible for the two motor shafts of the two electric motors to be mechanically operatively connected via a fifth spur gear stage.

The step of changing the driving range can include a step of controlling the power of the two electric motors, so that both electric motors together can provide a required drive power in the desired driving range. This step can take place after closing the third switching element in order to switch to the desired driving range. The drive power required can be constant during the driving range change process. However, the required drive power can also vary, for example due to a request from the driver of the working machine. These steps of changing the driving range without any interruption in traction are based on the idea that, at least for a short time, only one of the two electric motors can provide the required drive power. For this, an electric motor can be subjected to a greater load for a short time. Any overheating that may occur as a result during continuous operation can be avoided since a shifting process and overall the change of driving range can be very short, for example equal to or shorter than one second. Due to this short period of time, this electric motor can also be operated in an inefficient operating range without the overall efficiency of the drive train dropping to a relevant extent. Rather, the working machine can be operated more efficiently overall in many operating states due to the change of driving range without any interruption in the train.

In a further embodiment of the drive train, it can be provided that during the step of changing the driving range, at least one of the two electric motors is at least temporarily operated above a continuous load operating range of this electric motor. For example, the primary motor can be operated above its continuous load operating range if the primary motor alone provides the required drive power in the current driving range. For example, the secondary motor can be operated above its continuous load operating range if the secondary motor alone provides the required drive power in the intermediate driving range. A continuous load range can be a load range in which an electric motor can be operated without damage and, alternatively or additionally, excessive wear. A continuous load range can be defined, for example, by a temperature class of an electric motor's insulation. Derating or even shutdown usually occurs above the continuous load range. Above the continuous load operating range, the electric motor is threatened with increased wear and rapid overheating due to the principle of operation. However, since the change of driving range does not last longer than one second, for example, no actual increased wear or damage is to be expected during the change of driving range, even when operating above the continuous load operating range. This means that the electric motors do not have to be designed for continuous operation at peak load when changing driving ranges. This allows the electric motors to be small and be inexpensive. If there is no change in driving range, the electric motors can be operated, for example, within their respective continuous load range.

A third aspect relates to a work machine with a drive train according to the first aspect. The respective advantages and further features can be found in the description of the first aspect, with configurations of the first aspect also forming configurations of the third aspect and vice versa. The output shaft is designed to drive a traction drive of the working machine. For example, the output shaft is permanently mechanically operatively connected to the respective wheels of the working machine. The output shaft may be rotatably mounted on the work machine, as may respective input shafts. The electric motors can be attached to the working machine. The work machine can have an energy source for the power train.

In a further embodiment of the working machine, it can be provided that the working machine has a control device which is designed to operate the power train with a method according to the second aspect. The respective advantages and further features can be found in the description of the second aspect, with configurations of the second aspect also forming configurations of the third aspect and vice versa. The control device can be formed, for example, by the power electronics of the electric motors. The control device can have a microprocessor and alternatively or additionally one or more inverters. The control device can be designed to control a change in driving range without any interruption in traction. The control device can be designed to adjust the respective shifting elements of the drive train. The control device can be designed to switch between different operating modes of the power train.

Brief description of the figures

1 schematically illustrates a drive train of a work machine. FIG. 2 illustrates respective driving ranges of the drive train according to FIG. 1 with a tabular switching matrix.

3 schematically illustrates a first embodiment of a drive train of a working machine according to the invention.

FIG. 4 illustrates respective driving ranges of the drive train according to FIG. 3 with a tabular switching matrix.

FIG. 5 illustrates in tabular form a method for changing from a first driving range to a second driving range without any interruption in tractive force in the drive train according to FIG. 3.

FIG. 6 illustrates in tabular form a method for changing from the second driving range to a third driving range without any interruption in tractive force in the drive train according to FIG. 3.

FIG. 7 is a table showing a method for changing from the third driving range to a fourth driving range without any interruption in traction in the drive train according to FIG. 3.

FIG. 8 tabularly illustrates a method for changing from the fourth driving range to the third driving range without any interruption in traction in the drive train according to FIG. 3.

FIG. 9 illustrates in tabular form a method for changing from the third driving range to the second driving range without any interruption in tractive force in the drive train according to FIG. 3.

FIG. 10 illustrates in tabular form a method for changing from the second driving range to the first driving range without any interruption in tractive force in the drive train according to FIG. 3. 11 schematically illustrates a second embodiment of a drive train of a working machine according to the invention, which has a power take-off shaft.

Detailed Description of Embodiments

1 schematically illustrates an electric powertrain 100 for a work machine. The drive train 100 has a first electric motor EM1 with a first motor shaft 12 . The drive train 100 has a second electric motor EM2 which is arranged parallel thereto and has a second motor shaft 14 .

The drive train 100 has a shiftable transmission 116 . The transmission 116 has a first input shaft 22 which is formed by the first motor shaft 12 . The transmission 116 has a second input shaft 24 which is formed by the second motor shaft 14 . The transmission 116 has an output shaft 18 which forms a driven axle of the working machine. The transmission 116 is designed to transmit a torque from the two input shafts 22, 24 to the output shaft 18 with different gear ratios that can be selected.

The transmission 116 has a first form-fitting double shifting element S1 and a second form-fitting double shifting element S2. The transmission 116 has no further shifting elements. In addition, the transmission 116 has a first

Spur gear ST1, a second spur gear ST2, a third spur gear ST3 and a fourth spur gear ST4. In a first shift position of the first double shift element S1, the first input shaft 22 is mechanically operatively connected to the output shaft 18 with a first gear ratio via the first spur gear stage ST1. In a first shift position of the second double shift element S2, the second input shaft 24 is mechanically operatively connected to the output shaft 18 with a second gear ratio via the second spur gear stage ST2. In a second switching position of the first double shifting element S1 with a third gear ratio, the first input shaft 22 is mechanically operatively connected to the output shaft 18 via the third spur gear stage ST3. The second input shaft 24 is in a second shift position of the second double shift element S2 with a fourth gear ratio over the fourth Spur gear ST4 is mechanically operatively connected to the output shaft 18 . The transmission 116 has no further spur gear stages.

The first spur gear stage ST1 and the second spur gear stage ST2 jointly use a fixed gear that is permanently connected to the output shaft 18 in a torque-proof manner. The third spur gear stage ST3 and the fourth spur gear stage ST4 jointly use a fixed gear that is permanently connected to the output shaft 18 in a torque-proof manner. The output shaft 18 is arranged parallel to the first input shaft 22 and the second input shaft 24 . The first double shifting element S1 is arranged coaxially with the first input shaft 22 and is mounted on the first input shaft 22 . The second double shifting element S2 is arranged coaxially with the second input shaft 24 and is mounted on the second input shaft 24 .

Four driving ranges can be provided for the drive train 100 with the transmission 116 . The respective switching states of the two double switching elements S1, S2 are shown in the table in FIG. 2 for each of these driving ranges. In a driving range FB1.2, the first spur gear ST1 is used to transmit torque from the first motor shaft 12 to the output shaft 18 . Correspondingly, the switching position in the table of FIG. 2 for the first switching element S1 is illustrated as “1”. In the driving range FB1.2, the second spur gear ST2 is used to transmit torque from the second motor shaft 14 to the output shaft 18 . Correspondingly, the switching position in the table of FIG. 2 for the second switching element is illustrated with “2”. Both electric motors EM1, EM2 can jointly drive the output shaft 18 in driving range FB1.2, which is illustrated by the two “X”s in the table in FIG.

In a driving range FB2.3, the third spur gear stage ST3 is used to transmit torque from the first motor shaft 12 to the output shaft 18 and the second spur gear stage ST2 to transmit torque from the second motor shaft 14 to the output shaft 18. Accordingly, the shift position in the table of Fig. 2 is illustrated with “3” for the first shifting element S1 and with “2” for the second shifting element S2. Both electric motors EM1, EM2 can Driving range 2.3 drive the output shaft 18 together, which is illustrated by the two “X” in the table of FIG.

In a driving range FB3.4, the third spur gear ST3 becomes

Torque transmission from the first motor shaft 12 to the output shaft 18 is used and the fourth spur gear stage ST4 is used to transmit torque from the second motor shaft 14 to the output shaft 18. Accordingly, the shift position in the table of Fig. 2 is illustrated with “3” for the first shifting element S1 and with “4” for the second shifting element S2. Both electric motors EM1, EM2 can jointly drive the output shaft 18 in driving range 3.4, which is illustrated by the two “X”s in the table in FIG.

In a driving range FB4.0, the fourth spur gear ST4 is used to transmit torque from the second motor shaft 14 to the output shaft 18 . Correspondingly, the switching position in the table of FIG. 2 for the second switching element S2 is illustrated with “4”. In driving range FB4.0, however, the first electric motor EM1 does not drive the output shaft 18 . This is illustrated by a in the table of FIG. In the example of the transmission 16 shown, the gear ratio for driving by the first electric motor EM1 is too small.

Accordingly, only the second electric motor EM2 can drive the output shaft 18, which is again illustrated by an "X" in the table of FIG. In the exemplary embodiment shown, the first double shifting element S1 can be shifted into a neutral position. This is illustrated by a in the table of FIG. If the first double switching element S1 cannot provide a neutral position, the first electric motor S1 must otherwise be dragged along.

In practice, this means a significant loss of performance of the drive train 100 at high speeds. Only the drive power of the second electric motor EM2 is available in the driving range FB4.0. Accordingly, only the driving ranges FB1.2, FB2.3 and FB3.4 can be fully used with the two electric motors EM1, EM2. 3 schematically illustrates a first embodiment of an electric powertrain 10 with a transmission 16 for a work machine according to the invention. The drive train 10 and the transmission 16 have the same components as the drive train 100 and the transmission 116, which are therefore provided with the same reference numbers. However, the transmission 16 also has a third positive shifting element S3 and a fifth spur gear stage ST5. Otherwise, the transmission 16 and also the drive train 10 are free of additional components. With these additional components, the drive train 10 can provide further driving ranges with mechanically simple means, so that the output shaft 18 can be driven with both electric motors EM1, EM2 in all driving ranges that are permanently used in operation. In addition, the flexibility of torque distribution and load distribution between the two electric motors EM1, EM2 is increased. Both double shifting elements S1, S2 have a neutral position in the transmission 16.

The first input shaft 22 can be mechanically operatively connected to the second input shaft 24 by means of the third shifting element S3 via the fifth spur gear stage ST5. The fifth spur gear ST5 is multi-stage. A loose wheel of the fifth spur gear stage ST5 can be connected in a torque-proof manner to the first input shaft 22 by means of the third shifting element S3. For this purpose, the third shifting element S3 is arranged coaxially with the first input shaft 22 and is mounted on the first input shaft 22 . A fixed wheel is permanently non-rotatably connected to the second input shaft 24 . A middle loose wheel is mounted on the output shaft 18, for which the output shaft 18 in the transmission 16 compared to the transmission 116 is lengthened axially in the direction of the two electric motors EM1, EM2. In the embodiment shown, the fifth spur gear stage ST5 provides a neutral translation. This means that the rotational speed of the two input shafts 22, 24 is the same when the third switching element S3 is closed. This construction is particularly easy to implement if the two motor shafts 12, 14 are equally spaced parallel to the output shaft 18, as shown. As a result, both electric motors EM1, EM2 can each simply apply half of the load in normal operation without a switching process, provided that the two electric motors EM1, EM2 are of identical design. The transmission 16 of the drive train 10 can also provide the driving ranges FB1.2, 2.3 and 3.4, like the transmission 116. This and other driving ranges of the drive train 10 are illustrated in the table according to FIG. 4, which uses the same nomenclature as the table according to FIG. In each of the driving ranges FB1.2, FB2.3 and FB3.4, the third shifting element is open, which is illustrated by a in FIG. However, the driving ranges FB1.2, 2.3 and 3.4 are not used in the drive train 10 in regular operation, but only for driving range changes without any interruption in tractive force, which can also be seen with reference to FIGS. 5 to 11 will be described. The additional driving areas FB1, FB2, FB3 and FB4 are used for a ferry operation, in which the drive power of both

Electric motors EM1, EM2 can be provided and is then transmitted to the output shaft 18 together via the same spur gear stage of the first to fourth spur gear stages ST1 to ST4.

In the driving ranges FB1, FB2, FB3 and FB4, one of the two electric motors EM1, EM2 can also be shut down to increase efficiency in part-load operation. At high speeds and low loads, the efficiency of an electric motor is relatively low. By shutting down one of the two electric motors EM1, EM2 in part-load operation, the losses in the electric motor operated alone with a greater load can be reduced. As a result, an overall efficiency of the drive train 10 can be increased in part-load operation. In one embodiment, this shutting down in the driving ranges FB1, FB2, FB3 and FB4 takes place automatically by a control device when the load falls below a minimum.

In the first driving range FB1, the first double shifting element S1 connects the first input shaft 22 to the output shaft 18 via the first spur gear stage ST1, which is illustrated with shift position “1”. The third switching element S3 is closed, which is illustrated with "X". Accordingly, that of the second

Torque generated by the electric motor EM2 is transmitted to the output shaft 18 via the first spur gear stage ST1 after it is first transmitted to the first input shaft 22 via the fifth spur gear stage ST5. The second double switching element S2 is in its illustrated neutral position. A drive torque of the two electric motors EM1, EM2 is added to the first input shaft 22 to together to drive the output shaft 18. This is also illustrated by “X” in FIG. 4 for the electric motors EM1, EM2. In part-load operation up to a predetermined maximum load, one of the two electric motors EM1, EM2 is shut down to increase efficiency. Once this predetermined maximum load is exceeded, this one of the two electric motors EM1, EM2 is automatically switched on.

In the second driving range FB2, the second double shifting element S2 connects the second input shaft 24 to the output shaft 18 via the second spur gear stage ST2, which is illustrated with shift position “2”. The third switching element S3 is closed, which is illustrated with "X". Correspondingly, the torque generated by the first electric motor EM1 is also transmitted to the output shaft 18 via the second spur gear stage ST2, after it has first been transmitted to the second input shaft 24 via the fifth spur gear stage ST5. The first double switching element S1 is in its illustrated neutral position. A driving torque of the two electric motors EM1, EM2 is added to the second input shaft 24 in order to drive the output shaft 18 together. This is also illustrated by “X” in FIG. 4 for the electric motors EM1, EM2. In part-load operation up to a predetermined maximum load, one of the two electric motors EM1, EM2 is shut down to increase efficiency. Once this predetermined maximum load is exceeded, this one of the two electric motors EM1, EM2 is automatically switched on.

In the third driving range FB3, the first double shifting element S1 connects the first input shaft 22 to the output shaft 18 via the third spur gear stage ST3, which is illustrated with shift position “3”. The third switching element S3 is closed, which is illustrated with "X". Correspondingly, the torque generated by the second electric motor EM2 is also transmitted to the output shaft 18 via the third spur gear stage ST3, after it has first been transmitted to the first input shaft 22 via the fifth spur gear stage ST5. The second double switching element S2 is in its with

illustrated neutral position. A driving torque of the two electric motors EM1, EM2 is added to the first input shaft 22 in order to drive the output shaft 18 together. This is also illustrated by “X” in FIG. 4 for the electric motors EM1, EM2. In part-load operation up to a predetermined maximum load, one of the two electric motors EM1, EM2 is for Increased efficiency shut down. Once this predetermined maximum load is exceeded, this one of the two electric motors EM1, EM2 is automatically switched on.

In the fourth driving range FB4, the second double shifting element S2 connects the second input shaft 24 to the output shaft 18 via the fourth spur gear stage ST4, which is illustrated with shift position “4”. The third switching element S3 is closed, which is illustrated with "X". Correspondingly, the torque generated by the first electric motor EM1 is also transmitted to the output shaft 18 via the fourth spur gear stage ST4, after it has first been transmitted to the second input shaft 24 via the fifth spur gear stage ST5. The first double switching element S1 is in its with

illustrated neutral position. A driving torque of the two electric motors EM1, EM2 is added to the second input shaft 24 in order to drive the output shaft 18 together. This is also illustrated by “X” in FIG. 4 for the electric motors EM1, EM2. In part-load operation up to a predetermined maximum load, one of the two electric motors EM1, EM2 is shut down to increase efficiency. Once this predetermined maximum load is exceeded, this one of the two electric motors EM1, EM2 is automatically switched on.

FIG. 5 illustrates a shift sequence for a driving range change from the first driving range FB1 to the second driving range FB2 without traction force interruption. First, both electric motors EM1, EM2 are controlled in such a way that they jointly provide 50% of the drive power currently required. Depending on the design and the required drive power, there is a different load distribution in other embodiments. At the beginning of the driving range change, the power of the first electric motor EM1 is controlled in such a way that, as the primary motor, it alone provides the required drive power in the current first driving range FB1. As soon as the first electric motor EM1 fully provides the required drive power, the third switching element S3 is opened. This is illustrated in FIG. 5 with a . The power supply to the second electric motor EM2, on the other hand, is switched off so that it no longer provides any power.

A speed of the second electric motor EM2 as a secondary motor is then synchronized with the desired second driving range FB2. The speed of the The second input shaft 24 is thereby adapted to a speed present on the output side of the second double shifting element S2 from the output shaft 18 via the second spur gear stage ST2. The form-fitting second double shifting element S2 can now be shifted from its neutral position into the shifting position in which the second input shaft 24 is connected to the second spur gear stage ST2. The second double switching element S2 is thus closed. The driving range FB1 .2 has now been engaged in the transmission 16 , so that both electric motors EM1 , EM2 drive the output shaft 18 . The driving area FB1.2 is only used as an intermediate driving area when changing driving areas from the first driving area FB1 to the second driving area FB2.

When the intermediate driving range is reached, the power of the second electric motor EM2 as a secondary motor is now controlled in such a way that it alone provides the required drive power in the current intermediate driving range FB1.2. As soon as the second electric motor EM2 fully provides the required drive power, the first double shifting element S1 is shifted into its neutral position. This is illustrated in FIG. 5 with a . In contrast, the power supply to the first electric motor EM1 is switched off, so that it no longer provides any power.

A rotational speed of the first electric motor EM1 as the primary motor is then synchronized with the desired second driving range FB2. The speed of the first input shaft 22 is adapted to a speed applied to the third shifting element S3 from the second input shaft 24 via the fifth spur gear stage ST5. Now the form-fitting third switching element S3 can be moved from its open position to its closed position, so that the two input shafts 22, 24 are mechanically operatively connected to one another. This is illustrated by an "X" for the switching element S3. The second driving range FB2 has now been engaged in the transmission 16 so that both electric motors EM1 , EM2 can drive the output shaft 18 . The two electric motors EM1, EM2 are now controlled again in such a way that they jointly provide 50% of the drive power that is currently required in the second driving range FB2 that is now engaged. Depending on In other embodiments, the load is distributed differently depending on the design and required drive power.

FIG. 6 illustrates a shift sequence for a driving range change from the second driving range FB2 to the third driving range FB3 without traction force interruption. First, both electric motors EM1, EM2 are controlled in such a way that they jointly provide 50% of the drive power currently required. Depending on the design and the required drive power, there is a different load distribution in other embodiments. At the beginning of the driving range change, the power of the second electric motor EM2 is controlled in such a way that, as the primary motor, it alone provides the required drive power in the current first driving range FB2. As soon as the second electric motor EM2 fully provides the required drive power, the third switching element S3 is opened. This is in Fig. 6 with a

illustrated. In contrast, the power supply to the first electric motor EM1 is switched off, so that it no longer provides any power.

A speed of the first electric motor EM1 as a secondary motor is then synchronized with the desired second driving range FB3. The speed of the first input shaft 22 is adapted to a speed present on the output side of the first double shifting element S1 from the output shaft 18 via the third spur gear stage ST3. The form-fitting first double shifting element S1 can now be shifted from its neutral position into the shifting position in which the first input shaft 22 is connected to the third spur gear stage ST3. The first double switching element S1 is thus closed. The driving range FB2.3 has now been engaged in the transmission 16 so that both electric motors EM1 , EM2 drive the output shaft 18 . The driving area FB2.3 is only used as an intermediate driving area when changing driving areas from the second driving area FB2 to the second driving area FB3.

When the intermediate driving range is reached, the power of the first electric motor EM1 as a secondary motor is now controlled in such a way that it alone provides the required drive power in the current intermediate driving range FB2.3. As soon as the first electric motor EM1 has the required drive power completely provides, the second double switching element S2 is moved to its neutral position. This is illustrated in FIG. 6 with a . The power supply to the second electric motor EM2, on the other hand, is switched off so that it no longer provides any power.

A speed of the second electric motor EM2 as the primary motor is then synchronized with the desired third driving range FB3. The speed of the second input shaft 24 is adapted to a speed present at the third shifting element S3 of the first input shaft 22 . Now the form-fitting third switching element S3 can be moved from its open position to its closed position, so that the two input shafts 22, 24 are mechanically operatively connected to one another. This is illustrated by an "X" for the switching element S3. The third driving range FB3 has now been engaged in the transmission 16 so that both electric motors EM1 , EM2 can drive the output shaft 18 . The two electric motors EM1, EM2 are now controlled again in such a way that they jointly provide 50% of the drive power that is currently required in the third driving range FB3 that is now engaged. Depending on the design and the required drive power, there is a different load distribution in other embodiments.

FIG. 7 illustrates a shift sequence for a driving range change from the third driving range FB3 to the fourth driving range FB4 without traction force interruption. First, both electric motors EM1, EM2 are controlled in such a way that they jointly provide 50% of the drive power currently required. Depending on the design and the required drive power, there is a different load distribution in other embodiments. At the start of the driving range change, the power of the first electric motor EM1 is controlled in such a way that, as the primary motor, it alone provides the required drive power in the current third driving range FB3. As soon as the first electric motor EM1 fully provides the required drive power, the third switching element S3 is opened. This is in Fig. 7 with a

illustrated. The power supply to the second electric motor EM2, on the other hand, is switched off so that it no longer provides any power. A speed of the second electric motor EM2 as a secondary motor is then synchronized with the desired fourth driving range FB4. The speed of the second input shaft 24 is adapted to a speed present on the output side of the second double shifting element S2 from the output shaft 18 via the fourth spur gear stage ST4. The form-fitting second double shifting element S2 can now be shifted from its neutral position into the shifting position in which the second input shaft 24 is connected to the fourth spur gear stage ST4. The second double switching element S2 is thus closed. The driving range FB3.4 has now been engaged in the transmission 16 so that both electric motors EM1 , EM2 drive the output shaft 18 . The driving area FB3.4 is only used as an intermediate driving area when changing driving areas from the third driving area FB3 to the fourth driving area FB4.

When the intermediate driving range is reached, the power of the second electric motor EM2 as a secondary motor is now controlled in such a way that it alone provides the required drive power in the current intermediate driving range FB3.4. As soon as the second electric motor EM2 provides the required drive power in full, the first double shifting element S1 is shifted into its neutral position. This is illustrated in FIG. 7 with a . In contrast, the power supply to the first electric motor EM1 is switched off, so that it no longer provides any power.

A speed of the first electric motor EM1 as the primary motor is then synchronized with the desired fourth driving range FB4. The speed of the first input shaft 22 is adapted to a speed applied to the third shifting element S3 from the second input shaft 24 via the fifth spur gear stage ST5. Now the form-fitting third switching element S3 can be moved from its open position to its closed position, so that the two input shafts 22, 24 are mechanically operatively connected to one another. This is illustrated by an "X" for the switching element S3. The fourth driving range FB4 has now been engaged in the transmission 16 so that both electric motors EM1 , EM2 can drive the output shaft 18 . The two electric motors EM1, EM2 are now controlled again so that they together a currently required drive power in the provide 50% of the second driving range FB2 that is now engaged. Depending on the design and the required drive power, there is a different load distribution in other embodiments.

8 illustrates a shift sequence for a driving range change from the fourth driving range FB4 to the third driving range FB3 without traction force interruption. The shifting sequence and the engine control take place in the reverse order to that for the upshift from the third driving range FB3 to the fourth driving range FB4—illustrated in FIG. 7.

9 illustrates a shift sequence for a driving range change from the third driving range FB3 to the second driving range FB2 without traction force interruption. The shifting sequence and the engine control take place in the reverse order to the upshifting from the second driving range FB2 to the third driving range FB3—illustrated in FIG. 6.

10 illustrates a shift sequence for a driving range change from the second driving range FB2 to the first driving range FB1 without any interruption in traction. The shifting sequence and the engine control take place in the reverse order to the upshifting from the first driving range FB1 to the second driving range FB2—illustrated in FIG. 6.

In the embodiment shown, the total duration of a driving range change is 1 second or less. During this short time, in one embodiment, that one of the two electric motors EM1, EM2 which alone provides the currently required drive power is operated above its continuous load operating range. Due to the short duration of the driving range change, the electric motor does not heat up in a thermally critical area.

11 schematically illustrates a second embodiment of an electric powertrain 10 of a work machine according to the invention. The power train 10 according to the second embodiment has the same components and functions as the first embodiment. The transmission 16 is also essentially the same educated. Correspondingly, in the second embodiment, a driving range change without interruption of tractive force can take place using the same method as in the first embodiment.

The drive train 10 also has a fourth form-fit shifting element S4, a sixth spur gear stage ST6 and a power take-off shaft 60. The second input shaft 24 is extended axially on a side facing away from the second electric motor EM2 and extends through the second double shifting element S4. The second input shaft 24 can be mechanically operatively connected to the PTO shaft 60 by means of the fourth shifting element S4 via the sixth spur gear stage ST6. In this way, the drive train 10 can additionally provide a mechanical power take-off at the power take-off shaft 60 . In another embodiment, the sixth spur gear stage ST6 is omitted.

The power train 10 according to the second embodiment can be operated in a traction drive mode and a power take-off mode. In the travel drive mode, the drive train 10 according to the second specific embodiment is operated like the first specific embodiment and the power take-off shaft 60 is decoupled due to a fourth shifting element S4 being in the open position. The fourth switching element S4 is closed in the tap operating mode.

In the tap operating mode, the third switching element S3 is open in a first sub-mode and the second double switching element S2 is in its neutral position. Then the two driving ranges FB1 and FB3 can be used to drive the output shaft 18 exclusively by the first electric motor EM1 via the first spur gear ST1 or the third spur gear ST3 for a travel drive, ie with two different translations. The second electric motor EM2 then exclusively drives the power take-off shaft 60 . In the first sub-mode, drive power can therefore be provided at the same time on the output shaft 18 and, independently of this, a power take-off on the power take-off shaft 60 .

In another specific embodiment, the fourth shifting element S4 is connected to the first input shaft 22 . Accordingly, then stand for a traction drive second driving area FB2 and the fourth driving area FB4 are available when using the first submode. The PTO shaft 60 is then driven by the first electric motor EM1 and the output shaft 18 by the second electric motor EM2.

To activate the tapping operation mode while driving with the work machine, you must first switch to the first driving range FB1 or the third driving range FB3. The second electric motor EM2 is then controlled in such a way that it does not provide any torque. The second double switching element is switched to its neutral position. In this way, the fourth positive-locking shifting element S4 can be engaged. In an alternative embodiment, the fourth shifting element S4 is designed to be frictionally engaged, which means that there is no need to control the second electric motor EM2 in such a way that it does not provide any torque.

In the tap operating mode, the third switching element S3 is closed in a second sub-mode, the second double switching element S2 is in its neutral position and the first double switching element S1 is in its neutral position. The output shaft 18 is not supplied with drive power and the work machine is at a standstill. In the second sub-mode, the two electric motors EM1, EM2 can drive the PTO shaft 60 together via the sixth spur gear stage ST6. The two powers of the electric motors EM1, EM2 add up on the second input shaft 24, in that the power provided by the first electric motor EM1 is transmitted to the second input shaft 24 via the fifth spur gear stage.

reference sign

10 power train

12 first motor shaft

14 second motor shaft

16 gears

18 output shaft

22 first input shaft

24 second input shaft

60 PTO

100 powertrain

116 shiftable gearbox

EM1 first electric motor

EM2 second electric motor

S1 first positive double switching element

S2 second form-fitting double switching element

S3 third positive shift element

S4 fourth positive shift element

ST1 first spur gear stage

ST2 second spur gear stage

ST3 third spur gear stage

ST4 fourth spur gear

ST5 fifth spur gear

ST6 sixth spur gear

Claims

patent claims

1. Electric drive train (10) for a working machine, wherein the drive train (10) has a first electric motor (EM1) with a first motor shaft (12) and a second electric motor (EM2) with a second motor shaft (14) and a switchable transmission (16) with an output shaft (18), the first motor shaft (12) forming a first input shaft (22) of the transmission (16) and the second motor shaft (14) forming a second input shaft (24) of the transmission (16), the transmission (16) having a first double shifting element (S1), a second double shifting element (S2) and a third shifting element (S3), the first input shaft (22) being mechanically operatively connected to the output shaft (18) in a first shifting position of the first double shifting element (S1) with a first gear ratio, the first input shaft (22) being mechanically operatively connected to the output shaft in a second shifting position of the first double shifting element (S1) with a third gear ratio (18) is mechanically operatively connected, wherein the second input shaft (24) is mechanically operatively connected to the output shaft (18) in a first shift position of the second double shifting element (S2) with a second gear ratio, wherein the second input shaft (24) is mechanically operatively connected to the output shaft (18) in a second shift position of the second double shifting element (S2) with a fourth gear ratio, and wherein the first input shaft (22) is mechanically operatively connected to the second input shaft (24) by means of the third shifting element (S3) is mechanically operatively connected.

2. Drive train (10) according to Claim 1, characterized in that the transmission (16) has a first spur gear stage (ST1), a second spur gear stage (ST2), a third spur gear stage (ST3) and a fourth spur gear stage (ST4), the first input shaft (22) being mechanically operatively connected to the output shaft (18) via the first spur gear stage (ST1) in the first switching position of the first double shifting element (S1), the first input shaft (2nd 2) in the second switching position of the first double shifting element (S1) is mechanically operatively connected to the output shaft (18) via the third spur gear stage (ST3), the second input shaft (24) being mechanically operatively connected to the output shaft (18) in the first shifting position of the second double shifting element (S2) with the second spur gear stage (ST2). is, wherein the second input shaft (24) in the second switching position of the second

Double switching element (S2) with the fourth spur gear (ST4) with the

Output shaft (18) is mechanically operatively connected.

3. Drive train (10) according to Claim 1 or 2, characterized in that the transmission (16) has a fifth spur gear stage (ST5), the first input shaft (22) being mechanically operatively connectable to the second input shaft (24) by means of the third shifting element (S3) via the fifth spur gear stage (ST5).

4. Drive train (10) according to claim 3, characterized in that a spur gear of the fifth spur gear (ST5) is rotatably mounted on the output shaft (18).

5. Drive train (10) according to any one of the preceding claims, characterized in that the third switching element (S3) is mounted on one of the two input shafts (22, 24).

6. Drive train (10) according to any one of the preceding claims, characterized in that each of the aforementioned switching elements of the transmission (16) is designed as a positive-locking switching element.

7. Drive train (10) according to one of the preceding claims, characterized in that the first double shifting element (S1) has a neutral position in which torque transmission from the first input shaft (22) to the output shaft (18) via the first double shifting element (S1) is interrupted, and the second double shifting element (S2) has a neutral position in which torque transmission from the second input shaft (24) to the output shaft (18) via the second double shifting element (S2) is interrupted.

8. Drive train (10) according to one of the preceding claims, characterized in that the first double shifting element (S1) is mounted on the first input shaft (22) and the second double shifting element (S2) is mounted on the second input shaft (24).

9. Drive train (10) according to any one of the preceding claims 2 to 8, characterized in that the first spur gear (ST1) and the second

Spur gear (ST2) share a spur gear and the third spur gear (ST3) and the fourth spur gear (ST4) share a spur gear.

10. Drive train (10) according to one of the preceding claims, characterized in that the drive train (10) has a fourth shifting element (S4) and a power take-off shaft (60), one of the two input shafts (22, 24) being mechanically operatively connectable to the power take-off shaft (60) by means of the fourth shifting element (S4).

11 . Method for operating a drive train according to one of the preceding claims, wherein the method has at least one step of operating the drive train with one of the following driving ranges:

- First driving range, in which the third switching element (S3) is closed and the first double switching element (S1) is in its first switching position;

- Second driving range, in which the third switching element (S3) is closed and the second double switching element (S2) is in its first switching position;

- Third driving range, in which the third switching element (S3) is closed and the first double switching element (S1) is in its second switching position;

- Fourth driving range, in which the third switching element (S3) is closed and the second double switching element (S2) is in its second switching position; and wherein the method comprises at least one step of a driving range change from a current driving range to a desired driving range without traction interruption.

12. The method according to claim 11, characterized in that the step of changing the driving range has at least the following steps: - Control the power of the two electric motors (EM1, EM2), so that a

The primary motor of the two electric motors (EM1, EM2) alone provides a required drive power in the current driving range;

- Opening of the third switching element (S3);

- Synchronizing a speed of a secondary motor of the two electric motors (EMI, EM2) with the desired driving range;

- Insertion of an intermediate driving range by adjusting one of the two double switching elements (S1, S2) from its neutral position to a different position;

- Control the power of the two electric motors (EM1, EM2), so now the secondary motor alone provides a required drive power in the intermediate driving range;

- Adjusting the other of the two double switching elements (S1, S2) in its neutral position;

- synchronizing a speed of the primary motor with the desired driving range; and

- Closing the third switching element (S3) in order to switch to the desired driving range.

13. The method according to claim 11 or 12, characterized in that during the step of changing the driving range at least one of the two electric motors (EM1, EM2) is at least temporarily operated above a continuous load operating range of this electric motor.

14. Work machine with a drive train according to one of the preceding claims 1 to 10, wherein the output shaft (18) is designed to drive a drive output of the work machine.

15. Work machine according to claim 14, characterized in that the work machine has a control device which is designed to operate the drive train with a method according to one of claims 11 to 13.