DE102022200713B4 - Drive train for a work machine - Google Patents

Abstract

Electric drive train (10) for a work 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). an output shaft (18), wherein the first motor shaft (12) forms a first input shaft (22) of the transmission (16) and wherein the second motor shaft (14) forms a second input shaft (24) of the transmission (16), wherein the transmission (16) has a first double switching element (S1), a second double switching element (S2) and a third switching element (S3), wherein the first input shaft (22) in a first switching position of the first double switching element (S1) with a first gear ratio with the output shaft ( 18) is mechanically operatively connected, the first input shaft (22) being mechanically operatively connected to the output shaft (18) in a second switching position of the first double switching element (S1) with a third gear ratio, the second input shaft (24) being in a first switching position of the second Double switching element (S2) is mechanically operatively connected to the output shaft (18) with a second gear ratio, the second input shaft (24) being mechanically operatively connected to the output shaft (18) with a fourth gear ratio in a second switching position of the second double switching element (S2), and wherein the first input shaft (22) can be mechanically operatively connected to the second input shaft (24) by means of the third switching element (S3), the transmission (16) having a fifth spur gear stage (ST5), the first input shaft (22) being connected to the second input shaft (24 ) can be mechanically operatively connected by means of the third switching element (S3) via the fifth spur gear stage (ST5), characterized in that a spur gear of the fifth spur gear stage (ST5) is rotatably mounted on the output shaft (18), and 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) in the first switching position of the first double switching element (S1) via the first spur gear stage (ST1). the output shaft (18) is mechanically operatively connected, the first input shaft (22) being mechanically operatively connected to the output shaft (18) via the third spur gear stage (ST3) in the second switching position of the first double switching element (S1), the second input shaft (24) in the first switching position of the second double switching element (S2) with the second spur gear stage (ST2) is mechanically operatively connected to the output shaft (18), the second input shaft (24) in the second switching position of the second double switching element (S2) with the fourth spur gear stage (ST4 ) is mechanically operatively connected to the output shaft (18), the first spur gear stage (ST1) and the second spur gear stage (ST2) sharing a spur gear and the third spur gear stage (ST3) and the fourth spur gear stage (ST4) sharing a spur gear.

Description

Technical area

The present invention relates to a drive train for a work machine with two electric motors. The invention also 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. Through power splitting, both drive power and tap power can be provided by a single combustion engine. Transmissions adapted to internal combustion engines generally cannot be used for electric powertrains because electric motors and internal combustion engines have very different torque-speed characteristics.

The diverse range of uses of a mobile machine also requires a very large overall gear ratio of often more than 100 and sometimes even a total gear ratio of up to 1000. A continuously variable electric motor can in principle reproduce this spread without a gearbox, but only with noticeable restrictions in terms of performance and efficiency. For this reason, it is known to also use gearboxes 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 travel range with load interruption in practical use, at least with high tractive forces in combination with slow speeds. Without interrupting the load force, tractive force can continue to be provided even when changing the driving range. Wet multi-disc friction clutches are generally used as switching elements that can be switched without interrupting the load, but these generate high friction losses during a power shift and unwanted drag torques in the open state.

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

In the DE 10 2019 214 986 A1 a drive axle of an electric vehicle is described with a first electric machine and a second electric machine, whereby the second electric machine can be switched on as an additional drive if necessary.

In the WO 2019/206227 A1 A control strategy for a hybrid drive system with two electric motors, two double switching elements and a third switching element for connecting the two electric motors is described.

In the CN 1 03 770 639 A a drive arrangement with two electric motors, two double switching elements and a third switching element for connecting the two electric motors is described.

In the CN 1 05 042 045 A A drive arrangement with two horizontally placed drive motors and an associated transmission with two double switching elements and a third switching element are described.

In the CN 1 04 633 020 A A drive arrangement with a double motor and four-speed transmission is described.

In the CN 1 11 828 620 A A drive arrangement with a dual motor and a six-speed transmission with three modes is described.

In the US 2018 / 0 222 484 A1 a drive arrangement with two motors is described.

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 drive power and optionally additional power take-off. The drive power can be used to drive the work machine. The power draw can be used to supply power to an attachment of the work machine, such as an adjustable shovel. The work 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 work 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 power output of the work machine can be provided on 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 or formed by a rotor of the first electric motor. Furthermore, the drive train has a second electric motor with a second motor shaft. For example, a second power of the work machine can be provided on the second motor shaft. The second motor shaft can, for example, be connected to or formed by a rotor of the second electric motor. The designation as the second motor shaft only serves to assign it to the second electric motor. The second electric motor, for example, has no more than one motor shaft. The two electric motors can be designed as traction motors.

The drive train has a switchable transmission with an output shaft. For example, driving power can be provided at the output shaft by the drive train. The output shaft can be designed, for example, as a driving axle of the work 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 work machine can be moved over a surface, for example. The work machine can also have several drive axles, which are driven together or separately. The output shaft can, for example, be rotatably mounted on the work machine. By rotating the output shaft, for example, a travel movement of the work machine can be caused. 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. The work machine can stand on a surface with these wheels. In addition, the work machine can have respective driveless axes.

The transmission can provide different ratios between the electric motors and the output shaft. The translation can be changed by switching the transmission. For example, different driving areas can be provided. The transmission can be designed to provide several shiftable gears. For this purpose, the transmission can have respective switching elements. A translation 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 formed in one piece with the first input shaft or otherwise permanently connected in a rotationally fixed manner. However, the first motor shaft can also be connected to the first input shaft in a rotationally fixed manner, 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 formed in one piece with the second input shaft or otherwise permanently connected in a rotationally fixed manner. The second motor shaft can also be connected to the first input shaft in a rotationally fixed manner, for example if certain double switching elements of the transmission do not have a neutral position. A variable to be translated, such as torque, can be introduced into the transmission at an input shaft. Respective translated quantities, such as a torque or several torques combined, can be output at the output shaft.

The transmission has a first double shift element, a second double shift element and a third shift element. By switching these switching elements, different driving ranges can be provided, for example. A double switching element is a special form of a switching element. Accordingly, the transmission does not, for example, additionally have a first or second switching element, which differ from the first and second double switching elements. The numbering of the switching elements or double switching element serves to clearly assign them. The first double switching element can, for example, be arranged coaxially with the first input shaft. The second double switching element can, for example, be arranged coaxially with the second input shaft. The third switching element can, for example, be arranged coaxially with the first input shaft or the second input shaft. The result is a compact and simple design. 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 through a rigid coupling, and essentially interrupt this torque transmission in another state. For this purpose, a corresponding switching element can be provided between the two elements. A switching element can, for example, be designed to be frictionally or positively locking. An example of a frictional switching element is a multi-plate clutch. An example of a positive switching element is a claw clutch. A switching element can be closed by actuation. For example, a switching element can be actuated with oil pressure to enable torque transmission between two elements. A switching element may be biased towards its open state. At For example, a switching element can automatically adjust itself to its open state when oil pressure is lost in order to essentially interrupt the torque transmission between two elements.

A double switching element can be designed as a frictional or positive switching element. For example, the double switching 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 switching position of the double switching element, a different rotation-proof connection can be provided than in the second switching position of the double switching element. Optionally, the double switching element can have a third switching position in which no rotationally fixed connection is provided between two elements. The third switching 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, with a double switching element, one actuator may be sufficient for adjustment, while two individual switching elements may require two actuators.

The first input shaft is mechanically operatively connected to the output shaft in a first switching position of the first double switching element with a first gear ratio. The first input shaft is mechanically operatively connected to the output shaft in a second switching position of the first double switching element with a third gear ratio. The second input shaft is mechanically operatively connected to the output shaft with a second gear ratio in a first switching position of the second double switching element. The second input shaft is mechanically operatively connected to the output shaft in a second switching position of the second double switching element with a fourth gear ratio. Four different driving areas can be made available. In addition, the two electric motors can support each other in 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 work 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 switching element. This means that the electric motors can drive the machine together in four travel ranges, for example even in the highest travel range. In addition, this makes it possible to change the driving range without interrupting the train, even if the three switching elements mentioned above are designed to be form-fitting. For example, intermediate driving areas can be used for this. The drive train is correspondingly very powerful and efficient. In addition, a high level of flexibility in torque distribution and alternatively or additionally load distribution between the two electric motors is possible.

The input shafts can, for example, be arranged parallel to one another. 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 gear stages 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. This allows, for example, a high transmission spread to be achieved.

The transmission and the drive train as a whole can, for example, be free of switching elements other than those mentioned here. The transmission and also the drive train can also, for example, be free of moving elements other 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 asynchronous motor.

If two elements are mechanically connected, they are directly or indirectly coupled to one another in such a way that a movement of one element causes a reaction of the other element. For example, a mechanical active connection can be provided by a positive or frictional connection. For example, the mechanical active connection can correspond to a meshing of corresponding toothings of two elements. Additional elements, for example one or more spur gear stages, can be provided between the elements. A permanent, rotation-proof connection between two elements is understood to be 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 unwanted slippage can occur. Elements that are permanently connected in a rotationally fixed manner can be present as individual components that are connected to one another in a rotationally fixed manner or in one piece. A connection between two elements via another element can mean that this additional element is involved in an indirect active connection between the two elements. For example, this further element can be arranged in the flow of force between these two elements. A connection between two elements via two or more elements can mean that these additional elements are all involved in an indirect active connection between the two elements.

According to the invention, it is 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 stage is a cost-effective and very efficient design of a mechanical connection with a transmission. A spur gear stage can, for example, be designed in one or more stages. A single-stage spur gear stage can, for example, have two gears that mesh with one another. A two-stage spur gear stage can, for example, have three meshing gears. The gears of a spur gear stage can be designed as spur gears. Respective idler gears of a spur gear stage can, for example, be connected in a rotationally fixed manner to one of the input shafts via one of the two double switching elements. 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 switching position of the first double switching element, the first input shaft is mechanically operatively connected to the output shaft via the first spur gear stage. The first input shaft is mechanically operatively connected to the output shaft via the third spur gear stage in the second switching position of the first double switching element. The second input shaft is mechanically operatively connected to the output shaft with the third spur gear stage in the first switching position of the second double switching element. The second input shaft is mechanically operatively connected to the output shaft with the fourth spur gear stage in the second switching position of the second double switching element. The result is a simple, cost-effective and efficient drive train.

According to the invention it is provided that the transmission has a fifth spur gear stage. The gearbox can be free of spur gear stages other than those described here. The first input shaft can be mechanically operatively connected to the second input shaft by means of the third switching element via the fifth spur gear stage. This can result in a cost-effective and efficient design for a drive train with uninterrupted driving range change.

According to the invention, it is provided that a spur gear of the fifth spur gear stage is rotatably mounted on the output shaft. This means that this spur gear can be stored easily and in a space-saving manner. For example, the output shaft can extend axially beyond the two double switching elements and alternatively or additionally the first to fourth spur gear stages. The respective loads on the fifth spur gear stage can be well supported on the output shaft.

In a further embodiment of the drive train, it can be provided that the third switching element is mounted on one of the two input shafts. This makes the integration of the third switching element space-saving and easy. 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, it can be provided that the third switching element is designed as a positive switching element. Alternatively or additionally, it can be provided that the first double switching element is designed as a positive switching element. Alternatively or additionally, it can be provided that the second double switching element is designed as a positive switching element. For example, each of the aforementioned switching elements of the transmission can be designed as a positive switching element. Compared to a frictional switching element, a positive switching element can be more efficient and robust. With a positive switching element, it is not easy to change driving ranges without interrupting the tractive force. However, due to the mechanical operative connection of the first input shaft to the second input shaft by means of the third switching element, a change between, for example, four driving ranges without interruption in traction can only be made possible with positive switching elements. In comparison to a frictional switching element, no active control of positive switching elements is necessary during actuation. Respective switching positions of positive switching elements can essentially only be adjusted with respect to their end position, without adjustment dynamics having to be taken into account and controlled. This means that only low demands are placed on the switching actuators. Likewise, there is no need complex software to control the actuation.

In a further embodiment of the drive train, it can be provided that the first double switching element has a neutral position in which torque transmission from the first input shaft to the output shaft via the first double switching element is interrupted. Torque transmission from the first input shaft to the output shaft can continue to take place via the third switching element, the second input shaft and the second double switching element, for example when the second double switching element is not in its neutral position. Alternatively or additionally, it can be provided that the second double switching element has a neutral position in which torque transmission from the second input shaft to the output shaft via the second double switching element is interrupted. Torque transmission from the second input shaft to the output shaft can continue to take place via the third switching element, the first input shaft and the first double switching element, for example when the first double switching element is not in its neutral position. The neutral positions can provide an idle. In addition, respective intermediate travel ranges can be provided by the respective neutral position. Respective intermediate driving ranges can be used to change driving ranges without interrupting the tractive force.

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

According to the invention, it is provided that the first spur gear stage and the second spur gear stage 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 that is permanently connected to the output shaft in a rotationally fixed manner. According to the invention, it is 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 that is permanently connected to the output shaft in a rotationally fixed manner. This makes the gearbox compact and cost-effective. Very few parts are required. With different parallel spacing between the input shafts and the output shaft, a different gear ratio can still be provided by the two spur gear stages, which share a spur gear. Alternatively, the respective spur gear stages cannot share any spur gears. For example, a fixed gear that is permanently connected to the output shaft in a rotationally fixed manner can be provided for each spur gear stage. This makes the interpretation of the different translations particularly easy.

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

Additional spur gear stages can be provided between that of the two input shafts, which can be mechanically operatively connected to the PTO shaft by means of the fourth switching element, and the PTO shaft. The drive train can be designed in such a way that the mechanical operative connection between the PTO shaft and this input shaft can also be established when the respective double switching element is in its neutral position. This makes it possible to independently provide driving performance with one of the two electric motors and power draw 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 can be driven independently by the other of the two electric motors. The drive train can also have a power take-off gear, by means of which different translations can be provided between this input shaft and the power take-off shaft. By connecting the two input shafts through the third switching element, the PTO shaft can also be driven by both electric motors, for example if no traction drive is required. Particularly high power outputs can then be provided. A ground speed PTO function can also be provided.

A second aspect relates to a method for operating the power train according to the first aspect. Respective advantages and further features can be found in the description of the first aspect, with embodiments of the first aspect also embodiments of the second aspect and form 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 interrupting the tractive force. This means the drive train can be operated particularly powerfully and efficiently. The driving range change without interruption in tractive force can be carried out by changing successive driving ranges.

In a first driving range, the third switching element is closed and the first double switching element is in its first switching position. The second double switching element can be in its neutral position. In a second driving range, the third switching element is closed and the second double switching element is in its first switching position. The first double switching element can be in its neutral position. In a third driving range, the third switching element is closed and the first double switching element is in its second switching position. The second double switching element can be in its neutral position. In a fourth driving range, the third switching element is closed and the second double switching element is in its second switching 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. The four driving ranges are used, for example, in a first mode without a connected PTO. The optional fourth switching element is to be 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 switching 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 start of the driving range change and also before, the two electric motors can be controlled so that both electric motors jointly provide the currently required drive power.

The step of changing the driving range may 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 driving power in the current driving range. For example, a secondary motor of the two electric motors can be de-energized. 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 assigned, which results from the current and the desired driving range. For example, both electric motors can also be designed identically. Depending on the change in driving range, 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 may include a step of opening the third switching element. This opening of the third switching element can take place, for example, as soon as the primary motor completely alone provides the required drive power in the current driving range. This means that the required drive power can still 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 be done after opening the third switching element. For example, the speed of the secondary motor can be adjusted so that a double switching element 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 rotates at the same speed on both sides if the secondary motor corresponds to the second electric motor in the driving range change. For example, an output side of the second double switching element can be rotated via a spur gear stage for the desired travel range by the output shaft, which is further driven by the first electric motor. On the drive 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 switching element and a drive of the second double switching element rotate at the same speed.

The step of changing the driving range can have a step of inserting an intermediate driving range by adjusting one of the two double switching elements from its neutral position to another 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 switching element can be adjusted so that the output side of the second double switching element, which is connected to the spur gear stage for the desired driving range, is connected in a rotationally fixed manner to a corresponding input shaft. This also allows for a positive fit Double switching element can simply be closed starting from its neutral position. For example, in the intermediate travel range, both electric motors can drive the output shaft, but are connected to the output shaft with different 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 include a step of controlling the power of the two electric motors, so that the secondary motor alone now 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 adjusting the other of the two double switching elements into its neutral position. This adjustment to the neutral position can take place, for example, as soon as the secondary motor completely alone provides the required drive power in the current driving range. This means that the primary motor can now be decoupled from the output shaft. Nevertheless, the required drive power can still be provided in full 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 be done after adjusting the other of the two double switching elements to 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. This means that the third switching element can be closed without a speed difference. This means that a positive third switching element can also be easily closed.

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

The step of changing the driving range may include a step of controlling the power of the two electric motors so that both electric motors together provide a required drive power in the desired driving range. This step can be done after closing the third switching element in order to switch to the desired driving range. The required drive power 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 work machine.

These steps of changing the driving range without interruption of traction are based on the idea that, at least in the short term, only one of the two electric motors can provide the required drive power. To achieve this, an electric motor can be subjected to a larger load for a short period of time. Overheating that may occur during continuous operation can be avoided because a switching process and the overall change in 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 decreasing to any relevant extent. Rather, the working machine can be operated more efficiently overall in many operating states due to the uninterrupted travel range change.

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 operated at least temporarily 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 travel 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 insulation of an electric motor. Above the continuous load range, derating or even shutdown usually occurs. Above the continuous load operating range, the electric motor is inherently at risk of increased wear and rapid overheating. However, since the driving range change, for example, does not last longer than one Second, 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 during driving range changes. This allows the electric motors to be small and 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. Respective advantages and further features can be found in the description of the first aspect, with embodiments of the first aspect also forming embodiments of the third aspect and vice versa. The output shaft is designed to drive a drive output of the work machine. For example, the output shaft is permanently mechanically connected to the respective wheels of the work machine. The output shaft can be rotatably mounted on the work machine, as can respective input shafts. The electric motors can be attached to the work machine. The work machine can have an energy source for the power train.

In a further embodiment of the work machine, it can be provided that the work machine has a control device which is designed to operate the power train using a method according to the second aspect. Respective advantages and further features can be found in the description of the second aspect, with embodiments of the second aspect also forming embodiments 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 interruption in traction. The control device can be designed to adjust respective switching elements of the drive train. The control device can be designed to switch between different operating modes of the power train.

Short description of the characters

• 1 schematically illustrates a drive train of a work machine not according to the invention.
• 2 illustrates respective driving ranges of the drive train not according to the invention 1 with a tabular switching matrix.
• 3 schematically illustrates a first embodiment of a drive train according to the invention of a work machine.
• 4 illustrates the respective driving ranges of the drive train 3 with a tabular switching matrix.
• 5 illustrates in a table a method for a change without interruption in traction from a first driving range to a second driving range in the drive train according to 3 .
• 6 illustrates in a table a method for a change without interruption in traction from the second driving range to a third driving range in the drive train according to 3 .
• 7 illustrates in a table a method for a change from the third driving range to a fourth driving range without interruption in traction in the drive train according to 3 .
• 8th illustrates in a table a method for a change from the fourth driving range to the third driving range without interruption in traction in the drive train according to 3 .
• 9 illustrates in a table a method for a change from the third driving range to the second driving range without interruption in traction in the drive train according to 3 .
• 10 illustrates in a table a method for a change without interruption in traction from the second driving range to the first driving range in the drive train according to 3 .
• 11 schematically illustrates a second embodiment of a drive train according to the invention of a work machine, which has a PTO shaft.

Detailed Description of Embodiments

1 schematically illustrates an electric drive train 100 not according to the invention 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 arranged parallel thereto with a second motor shaft 14.

The drive train 100 has a switchable 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 work machine. The transmission 116 is designed to transmit torque with different selectable ratios from the two input shafts 22, 24 to the output shaft 18.

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

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

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

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 is used to transmit torque from the second motor shaft 14 to the output shaft 18. The switching position in the table of 2 for the first switching element S1 with “3” and for the second switching element S2 with “2”. Both electric motors EM1, EM2 can drive the output shaft 18 together in driving range 2.3, which is indicated by the two “X” in the table 2 illustrated.

In a driving range FB3.4, the third spur gear stage ST3 is used to transmit torque from the first motor shaft 12 to the output shaft 18 and the fourth spur gear stage ST4 is used to transmit torque from the second motor shaft 14 to the output shaft 18. The switching position in the table is corresponding 2 illustrated with “3” for the first switching element S1 and with “4” for the second switching element S2. Both electric motors EM1, EM2 can drive the output shaft 18 together in driving range 3.4, which is indicated by the two “X” in the table 2 is illustrated.

In a driving range FB4.0, the fourth spur gear stage ST4 is used to transmit torque from the second motor shaft 14 to the output shaft 18. The switching position in the table is corresponding 2 for the second switching element S2 illustrated with “4”. In driving range FB4.0, the first electric motor EM1 does not drive the output shaft 18. This is in the table of 2 illustrated by a “-”. In the example of the transmission 16 shown, the translation is too small for driving by the first electric motor EM1. Accordingly, only the second electric motor EM2 can drive the output shaft 18, which is again indicated by an “X” in the table of 2 is illustrated. In the exemplary embodiment shown, the first double switching element S1 can be adjusted to a neutral position. This is in the table of 2 illustrated by a “-”. Unless the first double switching element S1 is in a neutral position Otherwise, the first electric motor EM1 must 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 FB4.0 driving range. Accordingly, only the driving ranges FB1.2, FB2.3 and FB3.4 can be fully used with both electric motors EM1, EM2.

3 schematically illustrates a first embodiment of an electric drive train 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 numerals. However, the transmission 16 additionally has a third positive switching element S3 and a fifth spur gear stage ST5. Otherwise, the transmission 16 and also the drive train 10 are free of additional components. Through these additional components, the drive train 10 can provide additional driving ranges with mechanically simple means, so that the output shaft 18 can be driven by both electric motors EM1, EM2 in all driving ranges used permanently in operation. In addition, the flexibility of torque distribution and load distribution between the two electric motors EM1, EM2 is increased. Both double switching 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 switching element S3 via the fifth spur gear stage ST5. The fifth spur gear stage ST5 is designed in multiple stages. An idler gear of the fifth spur gear stage ST5 can be connected in a rotationally fixed manner to the first input shaft 22 by means of the third switching element S3. For this purpose, the third switching element S3 is arranged coaxially with the first input shaft 22 and is mounted on the first input shaft 22. A fixed gear is permanently connected to the second input shaft 24 in a rotationally fixed manner. A central idler gear is mounted on the output shaft 18, for which the output shaft 18 in the transmission 16 is extended axially in the direction of the two electric motors EM1, EM2 compared to the transmission 116. In the embodiment shown, the fifth spur gear stage ST5 provides a neutral translation. This means that a speed of the two input shafts 22, 24 is the same when the third switching element S3 is closed. This design is particularly easy to implement if the two motor shafts 12, 14, as shown, are spaced parallel to the output shaft 18. As a result, both electric motors EM1, EM2 can simply apply half of the load in normal operation without switching, provided the two electric motors EM1, EM2 are identical.

The transmission 16 of the drive train 10 can also provide the driving ranges FB1.2, 2.3 and 3.4, as can the transmission 116. This and other driving ranges of the drive train 10 are shown in the table 4 illustrating the same nomenclature as the table below 2 uses. In the driving ranges FB1.2, FB2.3 and FB3.4 the third switching element is open, which is indicated by a “-” in 4 is illustrated. However, the driving ranges FB1.2, 2.3 and 3.4 are not used in regular operation in the drive train 10, but only for driving range changes without interruption in tractive force, which can be seen from the 5 to 11 is described. The additional driving ranges FB1, FB2, FB3 and FB4 are used for driving, in which the drive power can be provided by both electric motors EM1, EM2 and then transmitted together to the output shaft 18 via the same spur gear stage of the first to fourth spur gear stages ST1 to ST4 becomes.

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 partial 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 partial load operation, the losses in the electric motor operated alone with a larger load can be reduced. As a result, the overall efficiency of the drive train 10 can be increased in partial load operation. In one embodiment, this shutdown occurs automatically in the driving ranges FB1, FB2, FB3 and FB4 by a control device when the load falls below a minimum.

In the first driving range FB1, the first double switching element S1 connects the first input shaft 22 with the output shaft 18 via the first spur gear stage ST1, which is illustrated with switching position “1”. The third switching element S3 is closed, which is illustrated by “X”. Correspondingly, the torque generated by the second electric motor EM2 is also 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 neutral position illustrated with “-”. A drive torque of the two electric motors EM1, EM2 is added to the first input shaft 22 to together drive the output shaft 18. This is also indicated by “X”. 4 for the electric motors EM1, EM2. In partial load operation up to a specified maximum load One of the two electric motors EM1, EM2 was shut down to increase efficiency. Once this specified maximum load is exceeded, one of the two electric motors EM1, EM2 is switched on automatically.

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

In the third driving range FB3, the first double switching element S1 connects the first input shaft 22 with the output shaft 18 via the third spur gear stage ST3, which is illustrated with switching position “3”. The third switching element S3 is closed, which is illustrated by “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 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 neutral position illustrated with “-”. A drive torque of the two electric motors EM1, EM2 is added to the first input shaft 22 to together drive the output shaft 18. This is also indicated by “X”. 4 for the electric motors EM1, EM2. In partial load operation up to a specified maximum load, one of the two electric motors EM1 and EM2 is shut down to increase efficiency. Once this specified maximum load is exceeded, one of the two electric motors EM1, EM2 is switched on automatically.

In the fourth driving range FB4, the second double switching element S2 connects the second input shaft 24 with the output shaft 18 via the fourth spur gear stage ST4, which is illustrated with switching position “4”. The third switching element S3 is closed, which is illustrated by “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 is first transmitted to the second input shaft 24 via the fifth spur gear stage ST5. The first double switching element S1 is in its neutral position illustrated with “-”. A drive torque of the two electric motors EM1, EM2 is added to the second input shaft 24 to together drive the output shaft 18. This is also indicated by “X”. 4 for the electric motors EM1, EM2. In partial load operation up to a specified maximum load, one of the two electric motors EM1 and EM2 is shut down to increase efficiency. Once this specified maximum load is exceeded, one of the two electric motors EM1, EM2 is switched on automatically.

5 illustrates a switching sequence for changing the driving range without interruption in traction from the first driving range FB1 to the second driving range FB2. First, both electric motors EM1, EM2 are controlled so that together they provide 50% of the currently required drive power. Depending on the design and the required drive power, a different load distribution occurs 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 in 5 illustrated with a “-”. However, the current supply to the second electric motor EM2 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 second input shaft 24 is adapted to a speed applied on the output side to the second double switching element S2 from the output shaft 18 via the second spur gear stage ST2. Now the form-fitting second double switching element S2 can be moved from its neutral position to the switching 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 transmission 16 is now in the driving range FB1.2, so that both electric motors EM1, EM2 drive the output shaft 18. The driving range FB1.2 is only used as an intermediate driving range when driving Range change from the first driving range FB1 to the second driving range FB2 is used.

When the intermediate travel range is reached, the power of the second electric motor EM2 as a secondary motor is now controlled so that it alone provides the required drive power in the current intermediate travel range FB1.2. As soon as the second electric motor EM2 fully provides the required drive power, the first double switching element S1 is moved to its neutral position. This is in 5 illustrated with a “-”. However, the current 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 second driving range FB2. The speed of the first input shaft 22 is adapted to a speed applied to the third switching element S3 from the second input shaft 24 via the fifth spur gear stage ST5. Now the positive third switching element S3 can be adjusted 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 together they each provide 50% of the currently required drive power in the second driving range FB2 that is now engaged. Depending on the design and the required drive power, a different load distribution occurs in other embodiments.

6 illustrates a switching sequence for changing the driving range without interruption in traction from the second driving range FB2 to the third driving range FB3. First, both electric motors EM1, EM2 are controlled so that together they each provide 50% of the currently required drive power. Depending on the design and the required drive power, a different load distribution occurs 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 6 illustrated with a “-”. However, the current 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 applied on the output side to the first double switching element S1 from the output shaft 18 via the third spur gear stage ST3. Now the positive first double switching element S1 can be moved from its neutral position to the switching 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 transmission 16 is now in the driving range FB2.3, so that both electric motors EM1, EM2 drive the output shaft 18. The driving range FB2.3 is only used as an intermediate driving range when changing the driving range from the second driving range FB2 to the second driving range FB3.

When the intermediate travel range is reached, the power of the first electric motor EM1 as a secondary motor is now controlled so that it alone provides the required drive power in the current intermediate travel range FB2.3. As soon as the first electric motor EM1 fully provides the required drive power, the second double switching element S2 is moved to its neutral position. This is in 6 illustrated with a “-”. However, the current supply to the second electric motor EM2 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 applied to the third switching element S3 of the first input shaft 22. Now the positive third switching element S3 can be adjusted 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 together they each provide 50% of the currently required drive power in the third driving range FB3 that is now engaged. Depending on the design and the required drive power, a different load distribution occurs in other embodiments.

7 illustrates a switching sequence for changing the driving range without interruption in traction from the third driving range FB3 to the fourth driving range FB4. First of all, both will be electric Motors EM1, EM2 are controlled in such a way that they together provide 50% of the currently required drive power. Depending on the design and the required drive power, a different load distribution occurs in other embodiments. At the beginning of the driving range change, the power of the first electric motor EM1 is controlled so 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 7 illustrated with a “-”. However, the current supply to the second electric motor EM2 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 applied on the output side to the second double switching element S2 from the output shaft 18 via the fourth spur gear stage ST4. Now the form-fitting second double switching element S2 can be moved from its neutral position to the switching 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 transmission 16 is now in the driving range FB3.4, so that both electric motors EM1, EM2 drive the output shaft 18. The driving range FB3.4 is only used as an intermediate driving range when changing the driving range from the third driving range FB3 to the fourth driving range FB4.

When the intermediate travel range is reached, the power of the second electric motor EM2 as a secondary motor is now controlled so that it alone provides the required drive power in the current intermediate travel range FB3.4. As soon as the second electric motor EM2 fully provides the drive power required, the first double switching element S1 is moved to its neutral position. This is in 7 illustrated with a “-”. However, the current 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 switching element S3 from the second input shaft 24 via the fifth spur gear stage ST5. Now the positive third switching element S3 can be adjusted 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 in such a way that together they each provide 50% of the currently required drive power in the second driving range FB2 that is now engaged. Depending on the design and the required drive power, a different load distribution occurs in other embodiments.

The 8th illustrates a switching sequence for changing the driving range without interruption in traction from the fourth driving range FB4 to the third driving range FB3. The switching sequence and the engine control take place in the reverse order as when upshifting from the third driving range FB3 to the fourth driving range FB4 - illustrated in 7 .

The 9 illustrates a switching sequence for changing the driving range without interruption in traction from the third driving range FB3 to the second driving range FB2. The switching sequence and the engine control take place in the reverse order as when upshifting from the second driving range FB2 to the third driving range FB3 - illustrated in 6 .

The 10 illustrates a switching sequence for changing the driving range without interruption in traction from the second driving range FB2 to the first driving range FB1. The switching sequence and the engine control take place in the reverse order as when upshifting from the first driving range FB1 to the second driving range FB2 - illustrated in 6 .

The total duration of a driving range change is 1 second or less in the embodiment shown. During this short time, in one embodiment, the 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 to a thermally critical range.

11 schematically illustrates a second embodiment of an electric drive train 10 a work machine according to the invention. The powertrain 10 according to the second embodiment has the same components and functions as the first embodiment. The transmission 16 is also designed essentially the same. Accordingly, the second can Embodiment, a driving range change without interruption of traction can be carried out using the same method as in the first embodiment.

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

The powertrain 10 according to the second embodiment can be operated in a traction drive mode and a piping operation mode. In the travel drive mode, the drive train 10 according to the second embodiment is operated like the first embodiment and the PTO shaft 60 is decoupled due to a fourth switching element S4 being in the open position. In the tapping operating mode, the fourth switching element S4 is closed.

In the tapping mode, the third switching element S3 is open in a first submode 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 stage ST1 or the third spur gear stage ST3 for a travel drive, i.e. with two different gear ratios. The second electric motor EM2 then exclusively drives the PTO shaft 60. In the first submode, drive power can be provided on the output shaft 18 and, independently of this, power take-off on the PTO shaft 60 at the same time.

In another embodiment, the fourth switching element S4 is connected to the first input shaft 22. Accordingly, the second driving range FB2 and the fourth driving range FB4 are then available for a travel drive when the first submode is used. 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 mode while driving the 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 so that it does not provide any torque. The second double switching element is switched to its neutral position. The fourth positive switching element S4 can thus be inserted. In an alternative embodiment, the fourth switching element S4 is designed to be frictionally engaged, which means that there is no need to control the second electric motor EM2 so that it does not provide any torque.

In the tapping mode, the third switching element S3 is closed in a second submode, 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 machine stands still. In the second submode, 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 by transmitting the power provided by the first electric motor EM1 to the second input shaft 24 via the fifth spur gear stage.

Reference symbols

10

Drivetrain

12

first motor shaft

14

second motor shaft

16

transmission

18

output shaft

22

first input wave

24

second input wave

60

PTO shaft

100

Drivetrain

116

switchable gearbox

EM1

first electric motor

EM2

second electric motor

S1

first positive double switching element

S2

second positive double switching element

S3

third positive switching element

S4

fourth positive switching element

ST1

first spur gear stage

ST2

second spur gear stage

ST3

third spur gear stage

ST4

fourth spur gear stage

ST5

fifth spur gear stage

ST6

sixth spur gear stage

Claims (11)

Electric drive train (10) for a work 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). an output shaft (18), wherein the first motor shaft (12) forms a first input shaft (22) of the transmission (16) and wherein the second motor shaft (14) forms a second input shaft (24) of the transmission (16), wherein the transmission (16) has a first double switching element (S1), a second double switching element (S2) and a third switching element (S3), wherein the first input shaft (22) in a first switching position of the first double switching element (S1) with a first gear ratio with the output shaft ( 18) is mechanically operatively connected, the first input shaft (22) being mechanically operatively connected to the output shaft (18) in a second switching position of the first double switching element (S1) with a third gear ratio, the second input shaft (24) being in a first switching position of the second Double switching element (S2) is mechanically operatively connected to the output shaft (18) with a second gear ratio, the second input shaft (24) being mechanically operatively connected to the output shaft (18) with a fourth gear ratio in a second switching position of the second double switching element (S2), and wherein the first input shaft (22) can be mechanically operatively connected to the second input shaft (24) by means of the third switching element (S3), the transmission (16) having a fifth spur gear stage (ST5), the first input shaft (22) being connected to the second input shaft ( 24) can be mechanically operatively connected via the fifth spur gear stage (ST5) by means of the third switching element (S3), characterized in that a spur gear of the fifth spur gear stage (ST5) is rotatably mounted on the output shaft (18), and 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) in the first switching position of the first double switching element (S1) via the first spur gear stage ( ST1) is mechanically operatively connected to the output shaft (18), the first input shaft (22) being mechanically operatively connected to the output shaft (18) via the third spur gear stage (ST3) in the second switching position of the first double switching element (S1), the second input shaft (24) is mechanically operatively connected to the output shaft (18) with the second spur gear stage (ST2) in the first switching position of the second double switching element (S2), the second input shaft (24) being in the second switching position of the second double switching element (S2) with the fourth Spur gear stage (ST4) is mechanically operatively connected to the output shaft (18), the first spur gear stage (ST1) and the second spur gear stage (ST2) sharing a spur gear and the third spur gear stage (ST3) and the fourth spur gear stage (ST4) sharing a spur gear . Drive train (10). Claim 1 , characterized in that the third switching element (S3) is mounted on one of the two input shafts (22, 24). Drive train (10) according to one of the preceding claims, characterized in that each of the aforementioned switching elements of the transmission (16) is designed as a positive switching element. Drive train (10) according to one of the preceding claims, characterized in that the first double switching 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 switching element (S1) is interrupted , and the second double switching 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 switching element (S2) is interrupted. Drive train (10) according to one of the preceding claims, characterized in that the first double switching element (S1) is mounted on the first input shaft (22) and the second double switching element (S2) is mounted on the second input shaft (24). Drive train (10) according to one of the preceding claims, characterized in that the drive train (10) has a fourth switching element (S4) and a PTO shaft (60), one of the two input shafts (22, 24) being connected to the PTO shaft (60) by means of the fourth switching element (S4) can be mechanically operatively connected. 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 changing the driving range from a current driving range to a desired driving range without interruption of traction. Procedure according to Claim 7 , characterized in that the step of changing the driving range has at least the following steps: - controlling the power of the two electric motors (EM1, EM2), so that a primary motor of the two electric motors (EM1, EM2) alone provides a required drive power in the current driving range; - Opening the third switching element (S3); - Synchronizing a speed of a secondary motor of the two electric motors (EM1, EM2) with the desired driving range; - Inserting an intermediate driving range by adjusting one of the two double switching elements (S1, S2) from its neutral position to another position; - Controlling the power of the two electric motors (EM1, EM2), so that the secondary motor alone provides the required drive power in the intermediate travel range; - Adjusting the other of the two double switching elements (S1, S2) to its neutral position; - Synchronizing a speed of the primary motor with the desired driving range; and - closing the third switching element (S3) to switch to the desired driving range. Procedure according to Claim 7 or 8th , characterized in that during the step of changing the driving range, at least one of the two electric motors (EM1, EM2) is operated at least temporarily above a continuous load operating range of this electric motor. Work machine with a drive train according to one of the preceding Claims 1 until 6 , wherein the output shaft (18) is designed to drive a drive output of the work machine. working machine Claim 10 , characterized in that the work machine has a control device which is designed to control the drive train using a method according to one of Claims 7 until 9 to operate.

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