DE102021209378B3 - Electric axle drive and motor vehicle - Google Patents

Abstract

Coupling device (3) for a transmission device (2) of a motor vehicle (1), which coupling device (3) has a first coupling device (7, 8) designed for selectively coupling a first drive element to a first output element (11, 12) and one for selective coupling a second drive element with a second output element (11, 12) has a second coupling device (7, 8), wherein the coupling device (3) has an actuator (13) arranged between the first and second coupling device (7, 8) which is designed for this purpose is to move a first coupling element (16, 16') of the first coupling device (7, 8) selectively into a coupling state and a decoupling state and a second coupling element (16, 16') of the second coupling device (7, 8) selectively into a coupling state and moving a decoupling state.

Description

The invention relates to an electric axle drive with two electric motors and a transmission device, the gear device having a coupling device, and a motor vehicle comprising such an electric axle drive.

Coupling devices for transmission devices of motor vehicles are basically known from the prior art. Such coupling devices are usually used to selectively couple drive elements to driven elements in order to ensure a power flow or a torque transmission from a drive to an output. For example, an output shaft of an electric machine can be connected or disconnected by the coupling device to an output element, which is coupled to a wheel of the motor vehicle, for example, depending on the operating situation of the motor vehicle or the transmission device.

Such coupling devices are usually actuated in a complex manner, for example by means of electromagnets, which move the coupling elements of the coupling device into certain positions or hold them in certain positions. However, such electromagnets are susceptible to high temperatures, are dependent on the supply voltage provided, require electrical energy for positioning the coupling element and holding a specific position of the coupling element and would have to be inefficient, especially with regard to use in traction drives for motor vehicles due to the high torques to be transmitted be dimensioned large. In particular, the use of an electromagnet cannot be scaled linearly with the torque to be transmitted, since the stroke range of the electromagnets used is extremely limited. If it is also necessary for more than one coupling element to be moved, an electromagnet would have to be provided in each case for moving the coupling elements. A corresponding sensor would therefore have to be assigned to each of the coupling elements, since the electromagnet itself does not permit monitoring of the positioning of the coupling elements.

DE 10 2010 051 977 A1 shows a mechanical axle drive. This has two couplings for decoupling the wheels of the axle.

The invention is based on the object of specifying an improved electric axle drive for a motor vehicle and a motor vehicle with an improved electric axle drive.

The object is achieved by an electric axle drive with the features of claim 1. Advantageous configurations are the subject matter of the dependent claims.

As described, the invention relates to an electric axle drive for a motor vehicle. The coupling device is designed to couple a drive element to a driven element or to release the coupling between the drive element and the driven element. For this purpose, the coupling device has a first coupling device and a second coupling device, the first coupling device being provided for selectively connecting a first drive element to a first driven element and the second coupling device being provided for selectively coupling a second drive element to a second driven element. In other words, the coupling device can influence the coupling state of the first coupling device and the second coupling device, so that it can be set whether the first drive element is coupled to the first driven element or the second drive element is coupled to the second driven element.

The invention is based on the finding that the first coupling device has an actuator, in particular an electromechanical actuator, which is arranged between the first and second coupling device and is designed to move a first coupling element of the first coupling device selectively into a coupling state and a decoupling state and a second coupling element to move the second coupling device selectively into a coupling state and a decoupling state. In other words, the same, in particular electromechanical, actuator is used to set the coupling state of the two coupling devices. In particular, this makes it possible to dispense with separately designed actuators, but instead to use the same actuator for the actuation of both coupling devices. This can, for example, result in advantages with regard to assembly, the installation space situation and the variety and number of parts.

By arranging the actuator between the two coupling devices, a particularly compact design can be achieved, particularly in the axial direction. Likewise, the two coupling devices can be actuated symmetrically, since the actuating movement can be generated centrally by the actuator and then symmetrically on the two coupling devices can be transferred. The arrangement of the actuator "between" the two coupling devices of the coupling device means in the context of this application in particular that the axial position on which the actuator is arranged lies between the axial positions on which the two coupling devices are arranged, for example on which the two coupling elements of the Coupling devices are arranged.

For example, a drive wheel can be understood as a drive element and a driven wheel can be understood as a driven element. The drive wheel and the driven wheel are connected to respective shafts, for example a drive shaft and a driven shaft. The output shaft can, for example, be coupled directly or indirectly to a wheel of the motor vehicle, so that torque that is transmitted to the output wheel via the coupling element can be passed on to the wheel of the motor vehicle. The drive shaft can be coupled directly or indirectly, for example via a pre-transmission, to the output shaft of a drive device, in particular an electric machine.

If the coupling device is closed, the coupling between the drive element and the driven element is established, ie torque can be transmitted from the drive device to the wheel or vice versa. In particular, form-fitting coupling elements can be used as coupling elements, for example claw elements. The coupling device can also be referred to as a so-called “disconnect unit”, since this allows the drive element to be decoupled from the driven element. In this way, it is possible in particular to save CO ₂ and fuel, since the coupling between the drive device and the wheel can be canceled in order to reduce unnecessarily rotating parts in the drive train.

In other words, the drive device and the drive elements assigned to it do not have to be carried along in all operating situations if they are not required. Each of the drive wheels or each of the drive elements can be driven by its own electric machine or generally by its own drive device. The individual coupling devices can thus ultimately be assigned to individual drive devices or individual drive train parts. For example, a first drive device for driving a first wheel can be provided and the coupling state can be set via the first coupling device. A second drive device for driving a second wheel of the motor vehicle can also be provided, it being possible for the second coupling device to set its coupling state.

The use of an electromechanical actuator makes it possible, in particular, to use the sensors of the electric motor to monitor the state of the coupling devices. The actuator described can have a current sensor and/or speed sensor and/or rotation angle sensor, which are designed to determine information, in particular a speed, a current and a rotation angle, which can be included in the monitoring of the coupling state.

According to one configuration of the coupling device, the first and the second coupling device of the coupling device can be arranged on the same axis of rotation, in particular symmetrically in relation to a center plane arranged between the first and second coupling device. The central plane can, for example, be perpendicular to the two axes of rotation of the first coupling device and the second coupling device. The axes of rotation can be, for example, the axes of rotation of the side shafts of the transmission device, which transmit the rotary movement to the wheels of the motor vehicle. Ultimately, the axis of rotation can also be defined by the output shafts or the drive wheel or output wheel of the respective coupling devices. The coupling devices can thus ultimately be arranged symmetrically with respect to the vehicle axis to which the coupling device is assigned. The output shafts, for example the side shafts, which lead to the wheels can be arranged parallel to the drive shafts of the drive devices, for example the electrical machines.

The first and the second coupling device can also be designed to move the first and second coupling element away from one another during a movement into the coupling state and towards one another during a movement into the decoupling state. When moving into the coupling state, the two coupling elements can thus be moved from one another, in particular away from the direction of a center point which is arranged between the two coupling elements. If the two coupling elements are moved into the decoupling state by the first coupling device or the second coupling device, the two coupling elements approach one another. The actuator that is used to operate the first and second coupling device or to move the first and second coupling element can here be arranged “inside” in relation to the drive wheels, ie closer to the center plane than the coupling elements , in particular, the actor in the middle lying flat. The actuator can be arranged in the axial direction between the two coupling devices, for example at an outer radial position which is further away than the housing of the two coupling devices.

According to a further embodiment of the electric axle drive, it can be provided that the first and the second coupling device are designed to move the first and second coupling element in a way that is coordinated with one another or coupled to one another. As described, the actuator is intended to move the coupling elements of the two coupling devices. The movement can be carried out synchronously, i.e. the actuator moves the coupling elements uniformly. A movement of the actuator thus triggers a movement of both coupling elements, which moves the coupling elements by the same distance.

In particular, this ensures that the two coupling devices are always brought into the same coupling state.

For example, if the two side shafts are to be coupled, a movement of the actuator is sufficient to switch both coupling devices from the decoupling state to the coupling state. It is also possible to bring both coupling elements from the coupled state into the decoupled state. In particular, a more complex sensor system can be dispensed with here, since the coupling of both coupling elements to the same actuator does not require a coordinated or synchronized movement, for example via a separate control device that determines the positions of the two coupling elements and, if necessary, activates separate actuators accordingly.

The actuator can be coupled to a switching device which is ultimately intended to convert the movement generated by the actuator into a movement of the coupling elements of the two coupling devices. In other words, the switching device is coupled to the actuator, so that the switching device transmits the movement of the actuator to the coupling elements. The switching device can have a first rocker switch and a second rocker switch, which are pivotably mounted about a common pivot axis. The two rocker switches can be arranged, for example, in the form of scissors or a scissor element and can be pivoted about a common pivot axis. For example, the pivot axis is designed as a pivot joint on which the two rocker switches are arranged one inside the other. The movement of the actuator thus causes the two rocker switches to be moved relative to one another, thereby moving the coupling elements coupled to them.

The two rocker switches can have toothed sections, for example, which can be in engagement with the actuator. For example, the actuator has a pinion that meshes with the toothed sections of the two rocker switches. The rotary movement of the actuator thus enables a displacement of the two rocker switches, in particular a pivoting of the rocker switch about the pivot axis. The pinion and the toothed sections can in particular be designed as crown teeth, so that each of the rocker switches has a corresponding toothed segment, for example in the shape of an arc, in particular in the shape of a circular arc. The rotary movement of the actuator thus leads to a pivoting movement of the two shift paddles in the crown gearing. In particular, the two rocker switches are moved uniformly, i.e. a certain rotational movement of the actuator leads to a deflection of the two rocker switches by the same angle.

For the previously described coupling of the switching devices to the actuator, the first switching device can have the first toothed section and the second switching device can have a second toothed section. The two toothed sections can be arranged at the same radial position and at different circumferential positions in relation to the axis of rotation. As described, the actuator, for example with a pinion, can engage between the two toothed sections and mesh with the toothed section. A rotary movement of the actuator can thus be converted into a linear movement of the two toothed sections and thus of the switching elements of the switching devices.

The arrangement of the two toothed sections in the same radial position ensures that both switching devices can ultimately experience the same lever ratios or the same actuating forces and actuating paths. The arrangement on the different circumferential positions allows, in particular, that the actuator can be arranged between the two toothed sections, the rotary movement being able to actuate the two switching devices simultaneously. For this purpose, the first toothed section can be moved by the actuator in an opposite direction relative to the second toothed section. In other words, for the rotational movement, the two toothed sections are displaced in different directions in the axial direction. For example, the first toothed section is displaced in the axial direction and the second toothed section is displaced counter to the axial direction or vice versa. the movement directions can also be referred to as the first axial direction and the second axial direction.

The coupling device can also have at least one spring device which is designed to build up a restoring force when there is a relative movement between a switching device and a coupling element. For example, the first coupling device has a first spring device and the second coupling device has a second spring device. If a relative movement between the coupling element and the switching device occurs in the respective coupling device, for example a relative movement between a switching ring and a sliding sleeve or a relative movement between a switching ring and the coupling element, the spring device can be deformed while the restoring force builds up.

In particular, if the coupling element is in a tooth-on-tooth position, i.e. the coupling element cannot be meshed directly because the teeth of the coupling element and the associated coupling partner are in contact with one another with their teeth in the axial direction, the spring device can be deformed. This allows the respective shifting device to be brought directly into its end position, with a relative movement between the shifting device and the coupling element being able to occur in the tooth-on-tooth position, which prestresses the spring device and builds up the restoring force. Thus, no monitoring of the position of the coupling element or a controlled movement of the coupling element has to be taken into account when a tooth-on-tooth position occurs. Instead, the movement can be carried out over the full circumference and the relative movement between the switching device and the coupling element can be generated when a tooth-on-tooth position occurs. Since the spring device is prestressed, when the tooth-on-tooth position is released, the coupling element moves into the end position, with the restoring force being reduced.

The coupling device can also have at least one damping device which is designed to damp a relative movement between a coupling element and a switching device, in particular when the restoring force is reduced. As described, the relative movement can be permitted in order to bring the switching device directly into an end position, so that when the tooth-on-tooth position occurs, the spring device is deformed and exerts a restoring force on the coupling element. If the tooth-on-tooth position is released, the spring force is abruptly reduced, so that this can lead to an abrupt "snapping" of the coupling element.

In this case, the damping device can damp the relative movement, in particular the reduction in the restoring force, so that the “snapping” cannot be perceived as disruptive by users of the motor vehicle. In this case, the damping device provides in particular an air volume which is sealed off by a seal. The damping device has a defined outlet for the air volume, which determines the throughflow of the air from the air volume in the event of a relative movement. Depending on how the damping device is dimensioned, the reduction of the restoring force or the relative movement takes place with more or less damping. In particular, a compromise can be found here between the fastest possible insertion movement and damping of the movement, so that there are no acoustic impairments.

The transmission device can preferably have a toothed wheel, in particular a spur wheel, as the drive element. The transmission device can preferably have a flange to a shaft to a wheel as the output element.

The electric axle drive preferably has two electric motors. Each of the electric motors can be connected to a wheel via one of the two coupling devices. In particular, the power flow can go from the electric motor via a gear, in particular a two-stage spur gear and then via the coupling device and further via a drive flange to a shaft. The shaft is then connected or connectable to a wheel.

Because of its configuration, the electric axle drive has a spur gear as the only gear between an electric motor and a wheel, in particular a two-stage spur gear. In other words, the electric axle drive is designed without a differential.

The power flows from the electric motors to the wheels are arranged mechanically independently of one another. Theoretically, one electric motor can transmit the full torque to “its” wheel and the other electric motor can stand still.

The invention further relates to a motor vehicle comprising such an electric axle drive. The motor vehicle has, in particular, two electrical machines which are arranged on the same axis of rotation. In particular, the two output shafts of the electrical machines point in opposite directions or the output shaft of the first electrical machine points in Direction of the second electrical machine and the output shaft of the second electrical machine points in the direction of the first electrical machine. The electrical machines are in particular arranged parallel to the coupling devices of the coupling device assigned to them. In this case, the output shafts of the electrical machines can be arranged parallel to the output shafts of the coupling devices, for example the side shafts.

• 1 einen Ausschnitt eines Kraftfahrzeugs, umfassend eine Getriebevorrichtung mit einer Kopplungsvorrichtung;
• 2 die Kopplungsvorrichtung des Kraftfahrzeugs von 1; und
• 3 die Kopplungsvorrichtung des Kraftfahrzeugs von 1, 2.

All advantages, details and features that have been described in relation to the electric axle drive can be fully transferred to the motor vehicle. The invention is explained below using an exemplary embodiment with reference to the figures. The figures are schematic representations and show:

• 1 a section of a motor vehicle, comprising a transmission device with a coupling device;
• 2 the coupling device of the motor vehicle from 1 ; and
• 3 the coupling device of the motor vehicle from 1 , 2 .

1 shows a schematic section of a motor vehicle 1 with a transmission device 2 and a coupling device 3. In this exemplary embodiment, the transmission device 2 has two electrical machines 4, 5, which are arranged on the same axis of rotation 6, with the output shafts of the electrical machine 4, 5 being aligned in this way are that they point to the other electrical machine 4, 5. In the context of the following description, the terms “first” and “second” have been chosen arbitrarily and can therefore also be arbitrarily interchanged or the corresponding description can be transferred. The electrical machine 4 can thus be referred to as the “first electrical machine 4” and the electrical machine 5 as the “second electrical machine 5” or vice versa. The respective components of the coupling device 3 can also be referred to as “first” and “second”. The individual designations are interchangeable.

in the in 1 In the representation shown, the output shafts of the electrical machine 4, 5 are coupled to the coupling device 3 via a pre-transmission. The coupling device 3 basically has a first coupling device 7 and a second coupling device 8 . The first coupling device 7 provides a first drive wheel 9 and the second coupling device 8 provides a second drive wheel 10, which can be driven by the electrical machines 4, 5 via the corresponding pre-transmission. The two coupling devices 7, 8 are arranged symmetrically in this exemplary embodiment, for example on a center plane arranged between the two coupling devices 7, 8. The center plane can, for example, be perpendicular to the axis of rotation 6 or perpendicular to an axis of rotation of the coupling devices 7, 8, which are arranged parallel to the axis of rotation 6 in this exemplary embodiment.

In this exemplary embodiment, the coupling devices 7, 8 are basically designed independently of one another to couple a first output element 11, in the case of the first coupling device 7, or a second output element 12, in the case of the second coupling device 8, or to cancel the coupling. In other words, the first coupling device 7 can establish or separate the coupling with the first output element 11 and the second coupling device 8 can establish or disconnect the coupling with the second output element 12 . The output elements 11, 12 can, for example, each be connected to a side shaft and thus transmit torque to a wheel of the motor vehicle 1.

2 shows a purely schematic representation of the coupling device 3 according to an embodiment. The arrangement of the individual elements is in 2 only to be understood as an example. Basically, the two coupling devices 7, 8 are designed symmetrically, so that the description of the first coupling device 7 can be transferred to the second coupling device 8 and vice versa. The coupling device 3 has a common actuator 13, which is designed as an electromechanical actuator in this exemplary embodiment. The actuator 13 meshes, for example with an output pinion, in a toothing 14, 14', which is coupled via a switching device 15 to a coupling element 16, 16'. The coupling elements 16, 16′ have, for example, claw teeth and can be brought into positive engagement with the driven element 11, 12 in order to produce the coupling state between the drive wheel 9, 10 and the driven element 11, 12. In this exemplary embodiment, the switching device 15 has two rocker switches 17, 17', which are coupled to the teeth 14, 14'. The teeth 14, 14' and the pinion of the actuator 13 can be designed, for example, in the form of crown gear teeth. The toothings 14, 14' can, for example, represent segments of a circle or arcuate segments which mesh with the crown wheel of the actuator 13. The rocker switch 17, 17' are pivoted about a common pivot axis 22. Depending on which movement the actuator 13 executes, the rocker switch 17, 17' can thus be moved in a scissor-like manner relative to one another, with the movement being transmitted to the coupling elements 16, 16' via the switching ring 18, 18'.

In other words, the actuator 13 can cause a corresponding movement of the teeth 14, 14' via the rotary movement of the pinion. The rotational movement of the actuator 13 thus causes an opposite axial movement of the switching rockers 17, 17', which are coupled to the switching rings 18, 18' via corresponding engagement elements which, for example, carry switching plates. Depending on the direction in which the actuator 13 rotates the pinion, the rocker switches 17, 17' and thus the switching rings 18, 18' and with them the coupling elements 16, 16' are moved toward or away from one another. If, for example, the coupling state is to be established, the actuator 13 will cause a corresponding rotational movement which moves the coupling elements 16, 16' away from one another and thus towards the drive elements 11, 12 in order to establish the coupling. If the output elements 11, 12 are to be decoupled, the actuator 13 performs the opposite rotational movement in order to move the coupling elements 16, 16' towards one another and away from the output elements 11, 12 in order to release the coupling with the output elements 11, 12.

In 3 the arrangement of the teeth 14, 14' and the switching devices 15, 15' is shown in a further view, for example a view rotated by 90° about the axis of rotation 6. As can be seen, the two toothings 14, 14', which are coupled to the switching rockers 17, 17', are arranged in the same radial position, ie they are at the same distance from the axis of rotation 6. However, these are arranged at different circumferential positions, ie the two rocker switches 17 , 17 ′ are arranged at different angles relative to the axis of rotation 6 , or an angle is formed between the rocker switches 17 , 17 ′ and the axis of rotation 6 .

If a so-called tooth-on-tooth position occurs between the coupling element 16 and the output element 11 or between the coupling element 16' and the output element 12, the actuator 13 can still bring the switching device 15 into its end position, i.e. in particular the respective switching rocker 17 , 17' and move the switching rings 18, 18' to their end position. In order to make this possible, the coupling device 3 has a spring device 19 which has at least one or more spring elements between the switching ring 18 and the coupling element 16 or between the switching ring 18' and the coupling element 16'. If the tooth-on-tooth position occurs and the respective switching rocker 17, 17' is continuously brought into its end position, the spring element or the spring elements of the spring device 19 are tensioned between the switching ring 18, 18' and the coupling element 16, 16'. before. If the tooth-on-tooth position is released, the coupling element 16, 16' can snap in, reducing the restoring force and relaxing the spring element of the spring device 19, 19'.

The two coupling devices 7, 8 also have reach-through elements 20, 20' on the coupling elements 16, 16', which reach through reach-through sections 21, 21' in the drive wheels 9, 10. This makes it possible for the drive wheels 9, 10 to be reached through and thus for an axial movement of the coupling elements 16, 16' to be carried out “from outside” by the actuator 13.

The advantages, details and features shown in the exemplary embodiments can be transferred to one another at will, interchanged with one another and combined with one another.

Reference List

1

motor vehicle

2

gear device

3

coupling device

4, 5

electric machine

6

axis of rotation

7, 8

coupling device

9, 10

drive wheel

11:12

output element

13

actuator

14, 14'

gearing

15, 15'

switching device

16, 16'

coupling element

17, 17'

paddle shifter

18, 18'

switching ring

19, 19'

spring device

20, 20'

penetration element

21, 21'

reach-through section

Claims (9)

Electric axle drive with two electric motors and a transmission device, the transmission device having a coupling device (3), characterized in that the coupling device (3) has a first coupling device (7, 8) and for selectively coupling a second drive element with a second output element (11, 12) designed second coupling device (7, 8), wherein the coupling device (3) has a between the first and second coupling device (7, 8) arranged actuator (13), which is designed to selectively move a first coupling element (16, 16') of the first coupling device (7, 8) into a coupling state and a decoupling state and a to move the second coupling element (16, 16') of the second coupling device (7, 8) selectively into a coupling state and a decoupling state. Electric axle drive after claim 1 , characterized in that the first and the second coupling device (7, 8) are arranged on the same axis of rotation (6), in particular symmetrically in relation to a center plane arranged between the first and second coupling device (7, 8). Electric axle drive after claim 1 or 2 , characterized in that the first and the second coupling device (7, 8) are designed to move the first and second coupling element (16, 16') away from one another during a movement into the coupling state and towards one another during a movement into the decoupling state . Electric axle drive according to one of the preceding claims, characterized in that the first and the second coupling device (7, 8) are designed to move the first and the second coupling element (16, 16') coupled to one another. Electric axle drive according to one of the preceding claims, characterized in that a switching device (15) has a first rocker switch (17, 17') and a second rocker switch (17, 17') which are pivotably mounted about a common pivot axis (22). Electric axle drive after claim 5 , characterized in that the switching device (15) has a first toothed section and a second toothed section for coupling to the actuator (13), the two toothed sections being arranged in the same radial position and in different circumferential positions in relation to the axis of rotation (6). Electric axle drive) according to one of the preceding claims, characterized by at least one spring device (19) which is designed to generate a restoring force when there is a relative movement between the first or second switching device (15) and the first or second coupling element (16, 16'). build up. Electric axle drive according to one of the preceding claims, characterized by a damping device which is designed to damp a relative movement between a coupling element (16, 16') and a switching device (15), in particular when the restoring force is reduced. Motor vehicle (1) comprising an electric axle drive according to one of the preceding claims.

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