DRIVE DEVICE FOR A VEHICLE AXLE OF A VEHICLE

Description

[0001] The invention relates to a drive device for a vehicle axle of a two-track vehicle according to the preamble of claim 1.

[0002] In an exemplary all-wheel-drive vehicle with electric drive, the front and rear axles can have at least one electric motor independent of each other. Depending on the driving situation, for example, the electric motor of the front axle may not be energized, while only the electric motor of the rear axle may be energized, so that the vehicle is driven solely by the rear axle. This increases overall efficiency and extends the range. However, with such rear-axle operation, friction losses (air and bearing friction, gear friction in the transmission, slip losses, etc.) occur due to the dragged-on, deactivated front axle drive.

[0003] DE 10 2015 210 227 A1 discloses a drive train for a motor vehicle with a clutch-controlled all-wheel drive. DE 20 2015 000 397 U1 discloses an actuating device for a dog clutch. DE 1 575 783 A discloses an electromagnetic clutch. DE 10 2016 224 864 A1 discloses a drive device of this type.

[0004] The object of the invention is to provide a drive device for a vehicle axle of a vehicle, in particular an electrically operated vehicle, in which drag losses in a deactivated drive unit can be reduced during driving operation.

[0005] The object is solved by the features of claim 1. Preferred developments of the invention are disclosed in the subclaims.

[0006] According to the invention, the drive unit outputs at least one drive shaft leading to a vehicle wheel. According to claim 1, this drive shaft is divided into a wheel-side shaft section and an axle-side shaft section, which can be coupled or decoupled from one another by means of a positive-lock coupling. In the decoupled state, no torque is transmitted between the wheel-side shaft section and the axle-side shaft section, thus avoiding drag losses in the deactivated drive unit during driving and when the drive unit is deactivated. In this way, for example, a vehicle axle (especially the front axle) can be coupled or decoupled as needed, preferably independently of the driving state.

[0007] According to the invention, the positive-lock coupling comprises a sliding sleeve that is arranged on a spline of a first shaft section in a rotationally fixed but axially displaceable manner. According to the invention, the sliding sleeve can be displaced by means of an axial actuating force generated by an actuator between an open coupling state, in which the sliding sleeve is brought out of the positive-lock connection with the second shaft section, and a closed coupling state, in which the sliding sleeve is brought into a positive-lock connection with the second shaft section.

[0008] Given the high package density in the area of the vehicle axle, a space-reduced, compact implementation of the positive-lock coupling including the actuator is of great importance. Against this background, according to the invention, an actuator sleeve is assigned to the actuator, which is arranged on a cylindrical sliding sleeve outer circumference. For rotational decoupling from the sliding sleeve rotating during operation, the actuator sleeve is mounted on the sliding sleeve outer circumference via at least one rotary bearing, preferably a rolling bearing, in such a way that the axial actuating force generated by the actuator is introduced into the sliding sleeve via the rotationally decoupled actuator sleeve and the rotary bearing, preferably a rolling bearing.

[0009] In a first embodiment, for actuating force transmission, both the bearing outer ring of the rolling bearing can be connected to the actuator sleeve in a way that transmits the actuating force, and the bearing inner ring of the rolling bearing can be connected to the sliding sleeve in a way that transmits the actuating force.

[0010] The actuator sleeve can be adjusted by the actuator between an open position, in which the positive-locking clutch is open, and a closed position. For this purpose, the actuator can interact with the actuator sleeve via a gear stage. In a space-saving implementation, this gear stage can have external teeth on the cylindrical outer circumference of the sliding sleeve. The teeth in the external teeth are spaced apart from one another in the axial direction and mesh with a gear of an actuator shaft of an electric motor, which forms the actuator.

[0011] Preferably, a positive-locking coupling is designed as a claw coupling, in which the sliding sleeve and the second shaft section have axially facing shift claws on the wheel and axle sides. The cylindrical outer circumference of the sliding sleeve can merge into the larger-diameter shift claws, forming an inner corner area. The actuator sleeve can be arranged in the thus formed inner corner area in a space-saving manner.

[0012] During the closing process of the above-mentioned claw clutch, the switching claws on the wheel and axle sides can lie opposite each other in the axial direction, tooth to tooth, so that a smooth positive engagement coupling can occur. In the more likely case, however, the switching claws initially come into contact tooth to tooth during the closing process. Once the tooth to tooth contact is reached, according to the invention the actuator sleeve is further adjusted to its closed position, specifically by building up a spring force from an overload spring that acts axially on the switching claws and braces the wheel and axle side switching claws against each other. As soon as a slight relative angular rotation of the two coupling halves brings the switching claws into a relative position tooth to tooth, the wheel and axle side switching claws can enter into a positive engagement as the spring force is reduced.

[0013] InIn a technical implementation, the wheel-side shifting claws can be formed on a carrier ring, which is arranged on the wheel-side shaft section in a rotationally fixed and axially displaceable manner via a spline. The carrier ring can be supported on its side axially opposite the axle-side shaft section against an axial stop of the wheel-side shaft section via the aforementioned overload spring. Therefore, if the wheel- and axle-side shifting claws come into tooth-to-tooth contact during the closing process of the claw clutch, the actuator sleeve together with the sliding sleeve is moved into the closed position, so that the sliding sleeve adjusts the carrier ring by a compensating stroke on the wheel-side shaft section while building up the spring force.As soon as a slight relative angular rotation of the two coupling halves causes the tooth to be in a gap, the positive connection is made, in which the wheel-side carrier ring comes into a positive connection with the axle-side switching claws by utilizing the above compensation stroke and reducing the spring force.

[0014] A second design variant is described below, in which the actuator sleeve no longer sits on the outer ring of the rolling bearing in a way that transmits the actuating force, but rather sits axially displaceably on the outer ring of the rolling bearing. The inner ring of the rolling bearing remains axially fixed and non-rotatably arranged on the sliding sleeve, i.e., it transmits the actuating force. An annular gap can be provided between the actuator sleeve and the cylindrical outer circumference of the sliding sleeve, in which the overload spring is arranged. The overload spring is supported axially between an actuator sleeve axial stop and the outer ring of the rolling bearing. During the closing process, the actuator sleeve and the sliding sleeve can thus be adjusted tooth by tooth in a motion-coupled manner until a contact is reached.Once the tooth-to-tooth contact is reached, the actuator sleeve is further adjusted to its closed position, decoupled from the sliding sleeve, while the spring force of the overload spring builds up. By slightly rotating the two coupling halves at a relative angle, the switching claws can be brought into a tooth-to-gap position, so that the sliding sleeve, along with the axle-side switching claws formed on it, is brought into a positive connection while the spring force of the overload spring is released.

[0015] Two embodiments of the invention are described below with reference to the attached figures.

[0016] They show: Figure 1 shows a roughly schematic representation of an electrically powered motor vehicle from above with highlighted, sketched vehicle axles; Figure 2 shows a drive device for the front axle of the vehicle; Figure 3 shows a partial view of a first embodiment of a claw clutch, which is shown in the open coupling state; Figure 4 shows a view corresponding to the Figure 3 , which illustrates a closing process of the claw coupling; Figures 5 and 6 each show views corresponding to the Figure 3 and 4 , which illustrates the functioning of the overload spring.

[0017] In the Figure 1An electrically powered motor vehicle is shown, which has an electrically driven front axle VA and an electrically driven rear axle HA. The front axle VA is equipped with exactly one electric motor EM, which drives via a front axle differential 3 to the left and right drive shafts 7, 9 leading to the right and left front wheels 5. The rear axle HA has a drive device in which, in contrast to the front axle VA, each of the rear wheels 15 is assigned an electric motor EM1, EM2, which are drivingly connected to the drive shafts 11 of the rear axle HA via gear ratios U1, U2. As can be seen from the Figure 1 As can be seen further, the front right drive shaft 9 is divided into a wheel-side shaft section 17 and an axle-side shaft section 19, which can be coupled or uncoupled from one another by means of a claw coupling 21.

[0018] When the claw clutch 21 is open, only a load-free compensating movement of the differential bevel gears 29 in the front axle differential 3 remains during driving. The rest of the drive unit (i.e. transmission and electric motor), on the other hand, come to a standstill, so that friction losses are greatly reduced.

[0019] For coupling (i.e., when the dog clutch 21 is closed), the electric motor EM is first energized, thus synchronizing the movable part of the dog clutch 21 to the current wheel speed. Once synchronization is almost achieved, the actuator 49 is activated. As described later, the actuator 49 acts via a toothing on a non-rotating actuator sleeve 53. This sleeve presses against the movable part of the dog clutch 21 via a spring-ball bearing combination.

[0020] According to the Figure 2The electric motor EM of the front axle VA is drivingly connected via a reduction gear 23 to an input-side external gear 25 of the front axle differential 3. On the output side of the front axle differential 3, axle bevel gears 27 are connected to the two drive shafts 7, 9. The axle bevel gears 27 and the toothed differential bevel gears 29 are positioned within a differential housing 31 of the axle differential 3.

[0021] The following is based on the Figure 3 and 4 The structure and operation of the claw clutch 21 according to a first embodiment are described. Figure 3 The axle bevel gear 27 is extended by a hollow axle shaft, which forms the axle-side shaft section 19. Radially inside the hollow axle shaft 19, a plug-in shaft is rotatably mounted, which leads to the front wheel 5 and forms the wheel-side shaft section 17. The claw coupling 21 has in the Figure 3axle-side shift claws 33 and wheel-side shift claws 35, which are positively connected to each other when the claw clutch 21 is closed. The axle-side shift claws 33 are in the Figure 3 Component of a sliding sleeve 37, which is arranged on a spline 39 of the hollow axle shaft 19 in a rotationally fixed but axially displaceable manner. The wheel-side shift claws 35 are formed on a carrier ring 41, which is mounted on the stub shaft 17 in a rotationally fixed but axially displaceable manner via a spline 43. The carrier ring 41 is supported on its side axially opposite the hollow axle shaft 19 against an axial stop 47 of the stub shaft 17 by means of an overload spring 45.

[0022] The sliding sleeve 37, which is arranged axially displaceably on the hollow axle shaft 19, is in the Figure 3can be actuated via an actuator 49, which is implemented as an electric motor. The actuator 49 is connected via a gear stage 51 to an actuator sleeve 53. This is arranged on a cylindrical sliding sleeve outer circumference 55. For rotational decoupling from the sliding sleeve 37 rotating during operation, the actuator sleeve 53 is mounted on the cylindrical sliding sleeve outer circumference 55 via two rolling bearings (optionally also plain bearings) 57, 59. In the Figure 3 An outer bearing ring 61 of the roller bearings 57, 59 is pressed into the inner circumference of the actuator sleeve 53, i.e., it is connected to the actuator sleeve 53 in a way that transmits the actuating force. Furthermore, an inner bearing ring 63 of the roller bearing 57, 59 is pressed onto the outer circumference 55 of the sliding sleeve, i.e., it is connected to the sliding sleeve 37 in a way that transmits the actuating force. In this way, an axial actuating force Fs generated by the actuator 49 is introduced into the sliding sleeve 37 via the rotationally decoupled actuator sleeve 53 and further via the two roller bearings 57, 59.

[0023] The gear stage 51 connected between the actuator 49 and the actuator sleeve 53 is in the Figure 3 by a drive gear 67 formed on an actuator shaft, which meshes with an external toothing 69 on the outer peripheral side of the sliding sleeve 37. The external toothing 69 has teeth spaced apart from one another in the axial direction.

[0024] The following is based on the Figure 3 A closing process of the claw clutch 21 is described, in which the wheel-side and axle-side shifting claws 33, 35 are axially opposite each other at tooth 58 and gap 60. In this case, the actuator 49 is activated to move the actuator sleeve 53, together with the sliding sleeve 37 coupled thereto, from the illustrated open position I into a closed position S, in which the wheel- and axle-side shifting claws 33, 35 are smoothly engaged.

[0025] Based on the Figure 4A closing process is described in which the wheel- and axle-side switching claws 33, 35 are not axially opposite each other at tooth 58 on gap 60, but rather at tooth 58 on tooth 58. In this case, during the closing process, the wheel- and axle-side switching claws 33, 35 initially come into contact with tooth 58 on tooth 58. Upon reaching the contact tooth 58 on tooth 58 ( Figure 4 ), the actuator sleeve 53 together with the sliding sleeve 37 is moved by an overload stroke Δh (in the Figure 4not shown) is further adjusted to the closed position II, whereby the carrier ring 41 is displaced on the stub shaft 17 by the overload stroke h while a spring force of the overload spring 45 builds up. As soon as tooth 58 is opposite gap 60 due to a slight relative angular rotation, the carrier ring 41 is suddenly brought into positive connection with the axle-side switching claws 33 of the sliding sleeve 37, while the overload stroke Δh is used up and the spring force of the overload spring 45 is reduced.

[0026] In the Figure 5 and 6 A second embodiment is shown in which the carrier ring 41 is no longer axially displaceable, but rather is pressed onto the stub shaft 17 in an axially fixed and rotationally fixed manner. The overload spring 45 is arranged in Figure 7 in an annular gap 71 between the actuator sleeve 53 and the cylindrical outer circumference 55 of the sliding sleeve.

[0027] In contrast to the first embodiment, in the Figure 5 The actuator sleeve 53 is no longer arranged to transmit the actuating force, but rather to be axially displaceable on the bearing outer ring 61 of the respective rolling bearing 57, 59. The bearing inner ring 63 of the rolling bearing 57, 59 is still axially fixed and rotationally fixed, i.e., to transmit the actuating force, on the sliding sleeve 37. The overload spring 45 is in the Figure 5 supported in the axial direction between an axial stop 73 of the actuator sleeve 53 and an intermediate disk 75. This is loosely positioned within the annular gap 71 and presses against the bearing outer ring 61 of the rolling bearing 57.

[0028] The following is a closing process of the Figure 5 claw coupling 21 shown. In the Figure 5the wheel- and axle-side shift claws 33, 35 are opposite each other with tooth 58 at gap 60, so that the actuator sleeve 53 together with the sliding sleeve 37 can be easily adjusted into the closed position II in a movement-coupled manner in order to establish a positive connection between the axle- and wheel-side shift claws 33, 35.

[0029] Based on the Figure 6 a closing process is illustrated in which the switching claws 33, 35 are positioned opposite each other tooth 58 to tooth 58. In this case, during the closing process, the actuator sleeve 53 together with the sliding sleeve 37 is first adjusted in a movement-coupled manner until the contact tooth 58 to tooth 58 is reached ( Figure 6 ). From the point of tooth 58 onwards, move to tooth 58 ( Figure 6), the actuator sleeve 53 is moved further into its closed position II by the overload stroke Δh - decoupled from the sliding sleeve 37 - while building up the spring force of the overload spring 45. By a slight relative angular rotation, the switching claws 33, 35 are brought into a relative position tooth 58 on gap 60, so that the switching claws 33, 35 can be brought into a positive connection suddenly while reducing the spring force.

[0030] To engage (close), the electric motor EM is first energized, thus synchronizing the movable part of the clutch to the wheel speed. Once synchronization is almost achieved, actuator 49 is activated, which acts on the non-rotating actuator sleeve 53 via a toothed system. This sleeve presses against the movable part of the claw clutch via a spring-ball bearing combination. LIST OF REFERENCE SYMBOLS.

[0031] 3 Front axle differential 5 Front wheels 7, 9 Front axle drive shafts 11 Rear axle drive shafts 15 Rear wheels 17 Wheel-side shaft section 19 Axle-side shaft section 21 Claw clutch 23 Countershaft 25 External gear 27 Axle bevel gears 29 Differential bevel gears 31 Differential housing 33 Axle-side shift dogs 35 Wheel-side shift dogs 37 Sliding sleeve 39 Spline 41 Carrier ring 43 Spline 45 Overload spring 47 Axial stop 49 Actuator 51 Gear stage 53 Actuator sleeve 54 Inner corner area 55 Cylindrical sliding sleeve outer circumference 57, 59 Rolling bearing 61 Bearing outer race 63 Bearing inner race 67 Drive gear 69External toothing 71Annular gap 73Axial stop 75Intermediate disc EM, EM1, EM2Electric machines U1, U2Transmission stages ΔhOverload stroke IOpen position IIClosed position

Claims

1. Drive device for a vehicle axle (VA) of a two-track vehicle, having a drive unit which outputs drive on the output side to at least one drive shaft (9) leading to a vehicle wheel (5), wherein the drive shaft (9) is divided into a wheel-side shaft portion (17) and into an axle-side shaft portion (19), which, by means of a form-fit clutch (21), are couplable in terms of drive to one another or decouplable in terms of drive from one another in order, during driving operation and with the drive unit (EM) deactivated, to avoid drag losses in the deactivated drive unit (EM), wherein the form-fit clutch (21) has a sliding sleeve (37) which is arranged rotationally conjointly but axially displaceably on a spline toothing (39) of a first shaft portion (17), and wherein the actuator (49) is assigned an actuator sleeve (53) which is arranged on a cylindrical sliding-sleeve outer circumference (55), characterized in that, for rotational decoupling from the sliding sleeve (37), which rotates during driving operation, the actuator sleeve (53) is mounted on the sliding-sleeve outer circumference (55) via at least one rotary bearing (57, 59) so that the axial actuating force (Fs) generated by an actuator (49) is introduced into the sliding sleeve (37) via the rotationally decoupled actuator sleeve (53) and the rotary bearing (57, 59), and in that, by means of an axial actuating force (Fs) generated by an actuator (49), the sliding sleeve (39) is displaceable between an open coupling state, in which the sliding sleeve (39) has been brought out of form-fitting connection with the second shaft portion (19), and a closed coupling state, in which the sliding sleeve (37) has been brought into form-fitting connection with the second shaft portion (17).

2. Drive device according to Claim 1, characterized in that, for transmission of actuating force, both a bearing outer ring (61) of the rotary bearing (57, 59) is attached in an actuating-force-transmitting manner to the actuator sleeve (53) and a bearing inner ring (63) of the rotary bearing (57, 59) is attached in an actuating-force-transmitting manner to the sliding sleeve (37).

3. Drive device according to Claim 1 or 2, characterized in that, by means of the actuator (49), the actuator sleeve (53) is adjustable between an open position (I), in which the form-fit clutch (21) is open, and a closing position (II), and / or in that the actuator (49) interacts with the actuator sleeve (53) via a transmission stage (51), and in that, for the realization of the transmission stage (51), an outer toothing (69) is formed on the outer circumferential side of the sliding sleeve (37), said outer toothing having teeth which are spaced apart from one another in an axial direction and being in toothed engagement with a gear (67) of an actuator shaft (65) of an electric motor (49).

4. Drive device according to one of the preceding claims, characterized in that the sliding sleeve (37) and the second shaft portion (17) have wheel-side and axle-side switching claws (33, 35) that face one another axially, and in that the cylindrical sliding-sleeve outer circumference (55) transitions into the switching claw (19), which has a larger diameter, such that an inner corner region is formed, and in that the actuator sleeve (53) is arranged in an expedient manner in terms of structural space in the inner corner region (54).

5. Drive device according to Claim 4, characterized in that, during the closing operation, either the wheel-side and axle-side switching claws (33, 35) are situated opposite one another with a tooth (58)-on-gap (60) configuration, so that a form-fitting connection is realized smoothly, or the switching claws (33, 35) firstly come into abutment with a tooth (58)-on-tooth (58) configuration, and in that, once the tooth (58)-on-tooth (58) abutment has been reached, the actuator sleeve (53) is adjusted further into the closed position (I), specifically with the build-up of a spring force of an overload spring (45), which acts axially on the switching claws (33, 35) and braces the switching claws (33, 35) against one another, and in that, by way of a slight relative angular rotation, the switching claws (33, 35) are brought into a tooth (58)-on-gap (60) relative position, so that the switching claws (33, 35) come into form-fitting connection with the reduction of the spring force.

6. Drive device according to Claim 4 or 5, characterized in that the wheel-side switching claws (35) are formed on a carrier ring (41) which is arranged in a rotationally conjoint and axially displaceable manner on the wheel-side shaft portion (17) via a spline toothing (43), and in that, on its side situated axially opposite the axle-side shaft portion (19), the carrier ring (41) is supported against an axial stop (47) of the wheel-side shaft portion (17) by means of the overload spring (45), and in that, in the case of a tooth (58)-on-tooth (58) abutment, the actuator sleeve (53), together with the sliding sleeve (37), is adjusted into the closed position (II) so that the sliding sleeve (37) adjusts the carrier ring (41) by an overload travel (Δh) on the wheel-side shaft portion (17) with the build-up of spring force.

7. Drive device according to Claim 5, characterized in that the actuator sleeve (53) is seated axially displaceably, that is to say not in an actuating-force-transmitting manner, on the bearing outer ring (61) of the rolling bearing (57, 59), and the bearing inner ring (63) of the rotary bearing (57, 59) is seated in an axially positionally fixed and rotationally conjoint manner, that is to say in an actuating-force-transmitting manner, on the sliding sleeve (37), and / or in that, between the actuator sleeve (53) and the cylindrical sliding-sleeve outer circumference (55), there is provided an annular gap (71) in which the overload spring (45) is arranged, and in that the overload spring (45) is supported between an axial stop (73) of the actuator sleeve (53) and the bearing outer ring (63) of the rolling bearing (57, 59) in the axial direction, and in that, during the closing operation, until the tooth (58)-on-tooth (58) abutment is reached, the actuator sleeve (53) and the sliding sleeve (37) are adjusted in a manner coupled in terms of movement, and, once the tooth (58)-on-tooth (58) abutment has been reached, the actuator sleeve (53) is adjusted in a manner decoupled in terms of movement from the sliding sleeve (37) further into the closing position (II), specifically with the build-up of the spring force of the spring element (45).