Wheel drive device and motor vehicle

Abstract

The invention relates to a wheel drive device for a motor vehicle, comprising a wheel hub (2) rotatably mounted about a wheel axis and a side shaft with a joint outer part (1), as well as a gearing device which has a first toothing (13) on the wheel hub side and a second toothing (12) on the joint outer part side, wherein the first toothing (13) engages with the second toothing (12), whereby the wheel hub (2) is rotationally fixed to the joint outer part (1), wherein the gearing device has an elastic axial locking device by means of which the wheel hub (2) is axially fixed to the joint outer part (1).

Description

[0001] The invention relates to a wheel drive device for a motor vehicle according to the preamble of claim 1 and a motor vehicle according to claim 8.

[0002] In motor vehicles, especially electrically powered vehicles, cracking noises can occur during start-up and load changes. Cracking noises occur particularly at the contact surface of a wheel bearing with a sideshaft or side drive shaft.

[0003] DE 10 2006 030 682 A1 describes a wheel hub constant velocity joint unit in which a wheel hub with a through-hole carrying an inner shaft toothing is clamped to the outer joint part of a constant velocity joint, on which a pin with an outer shaft toothing is formed, wherein the inner shaft toothing of the through-hole and the outer shaft toothing of the pin engage with one another and a double-row wheel bearing is pushed onto the wheel hub, which comprises an inner bearing ring on which an end face of the outer joint part is directly supported, wherein the pitch circle diameter of the rolling bearing is larger than the pitch circle diameter of the constant velocity joint.

[0004] Furthermore, DE 102 19 018 A1 and DE 10 2006 042 533 A1 show wheel hub drive devices in which at least one axial gap is arranged between those regions of the wheel hub and the outer joint part which are axially adjacent and radially overlapping with respect to the wheel rotation axis and which are arranged radially outside the toothing device.

[0005] The object of the present invention is to provide a novel wheel drive device for a motor vehicle and a novel motor vehicle, wherein in particular comfort properties are to be improved.

[0006] The object is achieved according to the invention by a wheel drive device for a motor vehicle having the features of claim 1 and by a motor vehicle having the features of claim 8.

[0007] Advantageous embodiments of the invention are the subject of the subclaims.

[0008] A wheel drive device for a motor vehicle is proposed, comprising a wheel hub mounted rotatably about a wheel rotation axis and a sideshaft with an outer joint part, as well as a toothing device which has a first toothing on the wheel hub side and a second toothing on the outer joint part side, wherein the first toothing is in engagement with the second toothing, whereby the wheel hub is connected in a rotationally fixed manner to the outer joint part.

[0009] In a manner known per se, at least one axial gap is always arranged between those regions of the wheel hub and the outer joint part which are axially adjacent and radially overlapping with respect to the wheel rotation axis and which are arranged radially outside the toothing device.

[0010] Furthermore, the wheel hub has a receptacle in the form of a hollow shaft section, on the inner circumference of which the first toothing is arranged, wherein a pin in the form of a cylinder section of the outer joint part is arranged radially inside the hollow shaft section and axially overlapping the hollow shaft section, wherein the second toothing is arranged on an outer circumference of the cylinder section, wherein a central screw is provided by means of which the outer joint part is secured axially to the wheel hub with respect to the wheel rotation axis.

[0011] According to the invention, an elastic axial securing device is provided by means of which the outer joint part is elastically secured axially relative to the wheel hub.

[0012] In this way, there is no area radially outside the gearing device in which a first surface of the outer joint part axially contacts a second surface of the wheel hub. In other words, there is no area radially outside the gearing device in which the first surface presses directly against the second surface. This prevents cracking noises caused by direct contact between these surfaces as a result of slight torsional movements between the wheel hub and the outer joint part, which can occur despite the gearing device.

[0013] Advantageously, the wheel hub and the outer joint part are each formed integrally from metal. The axial gap is arranged radially outside the gearing device and is located axially between the wheel hub and the outer joint part.

[0014] Furthermore, according to the invention, the gearing device has a helical interlock, by means of which the wheel hub is axially fixedly connected to the outer joint part. The elastic axial securing device thus has the helical interlock of the gearing device. Or, the elastic axial securing device is formed by the helical interlock of the gearing device.

[0015] Furthermore, according to the invention, the wheel hub has a contact surface arranged perpendicular to the wheel rotation axis for a screw head of the central screw, wherein an axial end of the cylinder section is arranged axially flush with the contact surface.

[0016] In one embodiment, the axial gap is arranged between an end of the wheel hub facing the outer joint part and the outer joint part.

[0017] Throughout this document, the terms “axial” and “radial” refer to the wheel’s axis of rotation.

[0018] In one embodiment, one of the gear teeth is a straight tooth or spur tooth running in the axial direction, while the other gear tooth deviates from a straight tooth by a certain amount.

[0019] Straight toothing refers to a toothing with teeth that are arranged parallel to the wheel's axis of rotation.

[0020] In one embodiment, the degree of helical twist is between 0° and 0.5° (i.e., between 0 and 30 arc minutes).

[0021] In one embodiment, the toothing of the wheel hub is a straight toothing, while the toothing of the outer joint part deviates from a straight toothing by the specified amount.

[0022] In one embodiment, the toothing of the outer joint part is a straight toothing, while the toothing of the wheel hub deviates from a straight toothing by the specified amount.

[0023] According to one aspect of the present invention, a multi-wheel motor vehicle is proposed, comprising one or more of the wheel drive devices described above.

[0024] The present invention proposes securing at least one sideshaft or side drive shaft of the motor vehicle without preload via a central screw and decoupling the wheel bearing preload from the assembly. A journal of the sideshaft is extended so that the screw head of the central screw rests on the end face of the journal of the sideshaft, thus securing the position of the sideshaft. The contact surfaces of the sideshaft and the wheel bearing, previously used in the prior art, do not come into contact with each other. A backlash-free connection is achieved by helical interlocking of the teeth on the journal of the sideshaft.

[0025] This prevents a stick-slip effect between the wheel bearing and the sideshaft.

[0026] This prevents cracking during start-up and load changes.

[0027] Embodiments of the invention are explained in more detail below with reference to drawings.

[0028] Showing: Fig. 1 is a schematic view of an outer joint part of a sideshaft of a motor vehicle according to the prior art, which is in engagement with a wheel hub of a wheel of the motor vehicle, and Fig. 2 is a schematic view of an outer joint part of a sideshaft of a motor vehicle according to an embodiment of the present invention, which is in engagement with a wheel hub of a wheel of the motor vehicle.

[0029] Corresponding parts are provided with the same reference numerals in all figures.

[0030] In the context of the present application, the term “rotatably fixed” is used as follows: Two rotatably mounted elements are connected to each other in a rotationally fixed manner if they are arranged coaxially to each other and are connected to each other in such a way that they rotate at the same angular velocity.

[0031] Furthermore, in the context of this application, the term "helical interlacing" is used with the following meaning: In a spline connection in which an inner shaft is rotationally fixed to a hollow shaft surrounding the inner shaft and arranged axially overlapping the inner shaft, the teeth of the inner shaft are slightly interlaced with the teeth of the hollow shaft. The extent of the interlacing is typically less than 1°. For example, the interlacing is 12 angular minutes (0.2°).

[0032] Fig. 1 is a schematic view of an outer joint part 1 of a sideshaft or lateral drive shaft of a motor vehicle, for example a passenger car, a commercial vehicle, or a bus, in particular with an electric drive and / or an internal combustion engine, according to the prior art. The outer joint part 1 engages with a wheel hub 2 of a wheel of the motor vehicle. For this purpose, the outer joint part 1 has a pin 3 that engages with an axial receptacle 4 of the wheel hub 2. The pin 3 and the axial receptacle 4 have mutually complementary straight toothings (not shown), by means of which the axial receptacle 4 is connected in a rotationally fixed manner to the pin 3.

[0033] The wheel hub 2 is arranged to rotate about a wheel rotation axis 16. The terms "axial" and "radial" used here refer to this wheel rotation axis 16.

[0034] The pin 3 has an axial bore 5 with an internal thread, into which a central screw 6 with an external thread is screwed. The central screw 6 has a screw head 7 that rests on a contact surface 8 of the wheel hub 2. The wheel hub 2 has an end face 9 at an axial end in the direction of the sideshaft, which serves as a stop for a complementary end face 10 of the outer joint part 1.

[0035] The end face 9 and the complementary end face 10 are advantageously arranged perpendicular to the wheel rotation axis.

[0036] An axial end 11 of the pin 3 inserted into the receptacle 4, facing the screw head 7, is spaced from the screw head 7 when the two end faces 9, 10 are in contact with each other. Fig. 1, the screw 6 is tightened until the end faces 9, 10 are in contact with each other, whereby an axial securing of the outer joint part 1 relative to the wheel hub 2 is provided.

[0037] Fig. Figure 2 shows a schematic view of an outer joint part 1 of a sideshaft or lateral drive shaft of a motor vehicle, for example a passenger car, a commercial vehicle, or a bus, in particular with an electric drive and / or an internal combustion engine, according to an embodiment of the present invention. The outer joint part 1 engages with a wheel hub 2 of a wheel of the motor vehicle. For this purpose, the outer joint part 1 has a pin 3 that engages with an axial receptacle 4 of the wheel hub 2.

[0038] The pin 3 and the axial receptacle 4 advantageously have mutually complementary toothings 12, 13, by which the axial receptacle 4 is connected in a rotationally fixed manner to the pin 3. The toothings 12, 13 particularly advantageously have a helical interlacing, in which one of the toothings 12, 13 has a toothing angle that deviates by a small amount from the toothing angle of the other toothing 12, 13. Accordingly, one of the toothings 12, 13 is a straight toothing extending in the axial direction, while the other toothing 12, 13 deviates from a straight toothing by a small amount, for example, twelve angular minutes (0.2°).

[0039] Due to the helical interlocking, at least one of the toothings 12, 13 deforms when the pin 3 is inserted into the receptacle 4. It has been found that this allows for elastic axial securing of the outer joint part 1 relative to the wheel hub 2. Furthermore, it has been found that improved radial securing of the outer joint part 1 relative to the wheel hub 2 can also be achieved. In other words, it has been found that a minimal radial play, which was observed with straight toothing, can be further minimized or even eliminated by the helical interlocking.

[0040] Due to the observed effect that the helical interlock provides elastic axial locking and, for example, additional elastic radial locking, axial and, for example, radial play can be minimized. Minimizing axial and, for example, radial play results in lower noise generation during load changes than with the current technology.

[0041] The pin 3 has an axial bore 5 with an internal thread into which a central screw 6 with an external thread is screwed. The central screw 6 has a screw head 7 that rests on a contact surface 8 of the wheel hub 2.

[0042] During assembly of the wheel hub 2 and outer joint part 1, the pin 3 is inserted into the axial receptacle 4, whereby initially only an incomplete insertion is possible due to the helical toothing. The central screw 6 is then screwed into the bore 5. When the screw head rests on the contact surface 8, the screw is turned further, whereby the pin 3 is drawn further into the receptacle 4 until the outer joint part 1 is firmly clamped to the wheel hub 2 due to the helical interlacing, but only to the extent that an axial gap 14 remains between the wheel hub 2 and the outer joint part 1 on the parts of the wheel hub 2 and the outer joint part 1 arranged radially outside the toothing 12, 13.

[0043] The wheel hub 2 can have an end face 9 on an inner side facing the sideshaft. The outer joint part 1 can also have an end face 10 at the level of a shoulder of the pin 3, which, when the pin 3 is inserted into the receptacle 4, is opposite the end face 9 but does not abut it. The axial gap 14 remains between the end faces 9, 10.

[0044] The axial gap 14 is brought about, for example, by the fact that the pin 3 has such a length in relation to a length of the receptacle 4 and / or to a distance between the end face 9 and the contact surface 8 that an outer end 11 of the pin 3 inserted into the receptacle 4 strikes the screw head 7 before the two end faces 9, 10 can come into contact with one another, so that the axial gap 14 remains between the two end faces 9, 10.

[0045] Alternatively, and not shown here, the axial gap 14 can also be created by using a shorter pin 3 which does not extend axially all the way to the contact surface 8 of the wheel hub 2, wherein the screw 6 is only tightened to such an extent that the axial gap 14 still remains.

[0046] In one embodiment, the receptacle 4 of the wheel hub 2 has a straight toothing 13, while the pin 3 of the outer joint part 1 has a toothing 12 that is inclined, for example, by 12' to the axial direction. Due to the helical interlocking, the wheel hub 2 and the outer joint part 1 can be pushed together by hand up to approximately two-thirds of the insertion length. The last third of the pushing together can be achieved by screwing in the central screw 6. This results in a slight deformation of at least one of the toothings 12, 13 and / or a wedging of the toothings 12, 13 into one another.

[0047] The outer joint part 1 is thus prevented from moving axially to the wheel hub 2 by the helical interlacing.

[0048] At the Fig. 1, a rattling noise occurs between the two end faces 9, 10 (torque transmission from the outer joint part 1 to the wheel hub 2) during dynamic load changes, particularly in electric drives. This rattling noise is eliminated by the inventive solution according to Fig. 2 prevented. List of reference symbols 1 outer joint part 2 wheel hub 3 cones 4 Recording 5 Hole 6 Central screw 7 screw head 8 contact surface 9 Frontal surface 10 Frontal area 11 outer end 12 Gearing 13 Gearing 14 Axial gap 16 Wheel rotation axis

Claims

[1] Wheel drive device for a motor vehicle, with a wheel hub (2) mounted rotatably about a wheel rotation axis and a sideshaft with an outer joint part (1), and with a toothing device which has a first toothing (13) on the wheel hub side and a second toothing (12) on the outer joint part side, wherein the first toothing (13) engages with the second toothing (12), whereby the wheel hub (2) is connected in a rotationally fixed manner to the outer joint part (1), wherein at least one axial gap (14) is arranged between those regions of the wheel hub (2) and the outer joint part (1) which are axially adjacent and radially overlapping with respect to the wheel rotation axis and which are arranged radially outside the toothing device, wherein the wheel hub (2) has a receptacle (4) in the form of a hollow shaft section, on the inner circumference of which the first toothing (13) is arranged, wherein a pin (3) in the form of a cylindrical section of the outer joint part (1) is arranged radially inside the hollow shaft section and axially overlapping the hollow shaft section, wherein the second toothing (12) is arranged on an outer circumference of the cylindrical section, wherein a central screw (6) is provided, by means of which the outer joint part (1) is secured axially to the wheel hub (2) with respect to the wheel rotation axis, characterized by an elastic axial securing device by means of which the outer joint part is elastically secured axially relative to the wheel hub (2), wherein the elastic axial securing device comprises a helical interlocking of the toothing device, wherein by means of the helical interlocking the wheel hub (2) is axially elastically connected to the outer joint part (1), wherein the wheel hub (2) has a contact surface (8) arranged perpendicular to the wheel rotation axis for a screw head (7) of the central screw (6), wherein an axial end (11) of the cylinder section is arranged axially flush with the contact surface (8). [2] Wheel drive device according to claim 1, characterized by that the axial gap (14) is arranged between an end of the wheel hub (2) facing the outer joint part (1) and the outer joint part (1). [3] Wheel drive device according to claim 2, characterized by that one of the toothings (12, 13) is a straight toothing running in the axial direction, while the other toothing (12, 13) deviates from a straight toothing by a certain extent of helical interlacing. [4] Wheel drive device according to claim 3, characterized by that the extent of helical entanglement is less than 1°. [5] Wheel drive device according to claim 4, characterized bythat the degree of helix twisting is at most 0.5°. [6] Wheel drive device according to one of claims 3 to 5, characterized by that the toothing (13) of the wheel hub (2) is the straight toothing, while the toothing (12) of the outer joint part (1) deviates from a straight toothing by the specified amount. [7] Wheel drive device according to one of claims 3 to 5, characterized by that the toothing (12) of the outer joint part (1) is a straight toothing, while the toothing (13) of the wheel hub (2) deviates from a straight toothing by the specified amount. [8] Multi-wheel motor vehicle comprising one or more wheel drive devices according to any one of the preceding claims.

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