Pass connection

Abstract

Pass connection, comprehensive a hub (10) with a toothed profile (13) on the inner circumference, an axle journal (20) with a toothed profile (23) on an outer circumferential section (24) and a shoulder (22) for axial support and / or contact against the hub (10), and a clamping device (30) for axially clamping the axle journal (20) to the hub (10), wherein the hub (10) has a constant tooth profile (13) over its tooth length, wherein the axle journal (20) has a first section (27) and a second section (28) with different tooth profiles (23a, 23b) along its tooth length, wherein the first section (27) is arranged on the insertion side, further away from the shoulder (22) than the second section (28) and has a constant tooth profile (23a) which has clearance with respect to the tooth profile (13) of the hub (10), and the second section (28) is arranged on the shoulder side and has a tooth profile (23b) with reduced tooth gaps compared to the first section (27), which is clearance-free with respect to the tooth profile (13) of the hub (10), and wherein the second section (28) is arranged such that it can only be pressed into the hub (10) without play after the first section (27) has been inserted into the hub (10) with some play by subsequently tightening the clamping device (30), characterized by the fact that the gear profile (23b) of the second section (28) is obtained by plastic forming from a gear profile corresponding to the gear profile (23a) of the first section (27), such that the pitch circle of the gear profile (23b) of the second section (28) is reduced by 0.1 to 1.2 times the gear module of the first section (27) compared to the pitch circle of the gear profile (23a) of the first section (27) with respect to the diameter.

Description

[0001] The invention relates to a fitting connection with the features of the preamble of claim 1.

[0002] Fitted connections, comprising a hub with a toothed profile on its inner circumference, a stub axle with a toothed profile on an outer circumferential section and a shoulder for axial contact with the hub, and a clamping device for axially clamping the stub axle to the hub, are commonly used in vehicle construction, for example, to connect a driveshaft to a driven vehicle wheel. Here, the stub axle of the driveshaft is clamped against the hub of a wheel bearing by means of a bolted connection, as is the case in Fig. Figure 1 is shown as an example. The screw connection can be provided on a short axle journal by screwing a fastening screw into an end face of the axle journal as a clamping device, as shown in Figure 1. Fig. As shown in Figure 1, or alternatively on a long axle journal with an external thread, onto which a nut is screwed as a clamping device. Other clamping devices are also possible.

[0003] In all cases, the clamping device provides axial support and / or contact of the axle stub against the wheel bearing hub. A corresponding shoulder is formed on the axle stub for this purpose. In a typical design, the clamping device preloads the wheel bearing, with the shoulder of the axle stub resting directly against the inner bearing race on the vehicle side. However, there are also designs in which the wheel bearing is preloaded by a deformation of the wheel hub. In this case, the shoulder of the axle stub rests against the deformed side of the wheel hub.

[0004] The torque transmission from the drive shaft to the vehicle wheel is normally achieved via the splined profiles on the axle stub and the wheel hub. However, due to the described axial preload, torque is also transmitted via friction at the shoulder surface of the axle stub. At this point, undesirable acoustic effects can occur when the torque overcomes static friction, resulting in a sudden, small relative movement between the shoulder and the supporting surface. This noise is known as a starting-up clunk or "ping noise."

[0005] This noise can occur repeatedly, especially when slipping also occurs in the opposite direction, for example when reversing or due to thrust torques such as those generated in recuperation mode in electric vehicles. The trend towards higher wheel torques (larger wheels and / or high motor torques) and the recuperation in electric vehicles exacerbates this problem.

[0006] The following solutions to the problem are generally possible at this point.

[0007] Firstly, the friction on the axle journal shoulder can be increased so significantly that slippage no longer occurs. This could be achieved, for example, through very rough, oil-free surfaces or by using intermediate layers of diamond fleece or diamond discs.

[0008] Secondly, the friction on the axle stub shoulder can be reduced to such an extent that no noise occurs during slippage. This could be achieved, for example, by using coated discs with a low coefficient of friction as an intermediate layer.

[0009] Thirdly, it is also possible to create a backlash-free connection, preventing any loosening and thus any impact between the components. This can be achieved, for example, by bonding, which, however, entails additional effort during assembly and in customer service, or by press-fitting the gear teeth.

[0010] From an economic point of view, the freedom from play achieved through compression is the desirable solution, as it does not require additional materials and components.

[0011] For an economical assembly process, however, additional tools and pressing devices should be avoided. Therefore, the challenge lies in achieving sufficient pressure while still ensuring that the components can be joined manually.

[0012] Various solutions for joining such fitting connections are known from the state of the art.

[0013] DE 14 25 231 A describes a splined shaft connection for the rotationally fixed connection of a motor vehicle axle shaft to a drive gear. This splined shaft connection has a continuously increasing backlash along the axial length of the teeth. For this purpose, the tooth gaps of the tooth profile of either the shaft or hub are continuously widened in the longitudinal direction of the teeth. During the manufacturing of the shaft or hub, the feed direction of the tool used to produce these tooth gaps is oriented obliquely to the shaft axis. However, such manufacturing is technically very complex and uneconomical for mass production.

[0014] DE 26 56 946 A1 describes a splined shaft connection in which the teeth and mating teeth mesh almost uniformly and without backlash for at least a small section of the splined shaft connection's length, while play exists in the remaining area. In this known splined shaft connection, the teeth and tooth gaps of the hub's splined profile are constant over the entire splined length. In contrast, the teeth of the longitudinally splined shaft are only of a constant thickness in an initial section beginning at the outer end face of the hub, and subsequently become progressively narrower towards the other side of the hub. Manual assembly is impossible in this case.

[0015] DE 43 02 726 C2 proposes a fitting connection between an axle journal and a wheel hub of a driven motor vehicle wheel, in which the teeth and tooth gaps of the tooth profile on the axle journal are constant over the entire tooth length. In contrast, the tooth profile of the hub is compressed from the side opposite the direction of power flow over only a first section of the tooth length, so that in this first section the teeth of the axle journal are pressed into the mating tooth gaps of the hub. The compression is achieved by pressing a ball into the hub, which is, however, somewhat complex. On the other hand, a simple initial insertion of the axle journal into the hub is possible, which can be carried out as part of automated assembly without any special centering effort – because of the play.The pressing in the first section can be carried out by actuating a fastening screw, by means of which the axle journal is axially clamped to the hub.

[0016] As already mentioned, the manufacturing process for producing the gear profile on the hub in DE 43 02 726 C2 is problematic. Furthermore, the backlash-free area of ​​the gear engagement is axially separated from the contact shoulder of the axle journal by a backlash-prone area. Within this backlash, a slight relative movement between the contact shoulder of the axle journal and the hub is still possible due to torsion of the components; that is, the previously described problem of noise generation in the form of a starting-up cracking or "ping noise" persists.

[0017] In practice, splined connections with a small helical angle on the axle journal have become established; that is, the tooth profile remains constant along the length of the toothing but winds around the longitudinal axis of the axle journal in a helical pattern. This helical angle can extend over the entire length of the toothing. However, the applicant is also aware of designs, particularly for long axle journals, in which a straight toothing is implemented in a first section and a helical toothing in a second section, or in which a first section has an angular offset relative to a second section.

[0018] Given the requirements of electric vehicles, which often have high starting torques and large wheels and therefore require high contact pressure in the gear teeth to prevent the slippage and associated noise described above, it becomes more difficult to achieve an economical manufacturing process under the two constraints of "manual assembly" and high contact pressure in the bolted state. The manufacturing tolerances for the splined connections would have to be significantly reduced, resulting in complex and expensive production.

[0019] The helix angle also leads to different properties in power transmission depending on the torque direction, which is disadvantageous for the design of the interface in terms of robustness.

[0020] A fitting connection with the features of the preamble of claim 1 is known from DE 10 2005 035 706 A1. Further fitting connections are known from EP 2 980 433 A1, FR 3 081 378 A1, DE 10 2016 210 578 A1, DE 10 2011 057 012 A1 and JP 2001 343023 A.

[0021] Against this background, the invention aims to provide alternatives for a generic fitting connection which, on the one hand, reduce the problem of noise formation during load changes and, on the other hand, make it possible to achieve a high pressure while taking into account economical, mass-production-ready manufacturing and still ensure that the components can be joined by hand, i.e. without additional pressing devices.

[0022] This problem is solved by a fitting connection according to claim 1. Special embodiments are the subject of further claims.

[0023] The solution according to the invention enables manual insertion of the axle journal into the hub without the need for a pressing device. By axially clamping the axle journal to the hub using the clamping device, the second section engages with the hub's tooth profile, thereby eliminating any play in the mating connection. The noise generation described above is reliably prevented, especially since the second section is located closer to the shoulder of the axle journal than the first section, thus preventing any significant rotation of the axle journal under torque. A small distance and consequently high torsional stiffness between the shoulder and the point of torque application to the splined connection, i.e., in the second section, fulfills this objective.In comparison to DE 43 02 726 C2, the manufacturing effort is also significantly lower, since the gear profile on the outer circumferential section of the axle journal can be produced more easily, particularly by rolling. Only this enables economical mass production.

[0024] The gear profile of the second section is obtained by plastic forming from a gear profile corresponding to that of the first section. This allows for the efficient production of a uniform gear profile along the entire length of the gear, for example by profile rolling, but also by other processes, and simple external post-processing of only a portion of this initially produced gear profile to obtain a modified profile shape in the second section for press-fitting with the gear profile of the hub.

[0025] In particular, the gear profile of the second section can be obtained by plastic forming from the outside, based on a gear profile corresponding to that of the first section. This gear profile is significantly more accessible from the radial outside than an internal gear on a hub. Furthermore, such forming can be carried out on the same manufacturing equipment directly following the gear rolling process.

[0026] Furthermore, a helical angle can optionally be superimposed on the tooth profile in the longitudinal direction of the toothing at the hub and / or at the first and / or second section of the axle journal, which is preferably in the range of 4 to 20 arc minutes.

[0027] To mesh the axle journal, the outer circumferential section can first be provided with a tooth profile corresponding to that of the first section along its entire tooth length, namely the area of ​​the first and second sections, using profile rolling. In a further step, the teeth in the area of ​​the second section are pressed radially inwards, reducing the pitch circle diameter. This allows for economical, high-volume production.

[0028] Preferably, the inward pressing is carried out by means of a roller which is axially displaced along the tooth length over the second section. Such a roller can be arranged spatially next to a profile roller of a manufacturing device for producing the tooth profile, so that both processes, rolling and inward pressing or embossing, can be carried out in immediate succession.

[0029] All gear profiles are hardened after shaping.

[0030] The invention will now be explained in more detail with reference to exemplary embodiments illustrated in the drawing. The drawing shows: Fig. 1. A longitudinal section view through a fitting between a drive shaft and a motor vehicle wheel to illustrate an example of a possible installation situation. Fig. 2 an embodiment of an axle journal according to the invention, Fig. 3. A diagram illustrating the production of the axle journal according to Fig. 2, and in Fig. 4 A schematic diagram illustrating the helical angle of a gear.

[0031] Fig. Figure 1 shows an example of the installation situation of a fitting according to the invention. A wheel bearing of a motor vehicle wheel with a hub 10 and an outer joint part of a constant velocity joint of a side shaft with an axle journal 20 are shown.

[0032] The axle journal 20 is inserted axially into the hub 10 and clamped axially against the hub 10 by means of a clamping device 30. An example of a clamping device 30 shown here is a fastening screw 31, which has a head 32 that rests against a wheel flange 40 and, via the flange, against the hub 10 of the wheel bearing. The fastening screw 30 is screwed into a corresponding threaded opening 21 of the axle journal 20 at its end face.

[0033] In a variation of the embodiment, a threaded section can be provided on the end face of the axle journal 20, onto which a fastening nut is screwed as a clamping device 30, which in turn is supported against the hub 10.

[0034] Fig. Figure 1 shows the wheel bearing and the side shaft in a partially assembled state, which is achieved by further axially pushing the wheel bearing and side shaft together and then axially clamping them using the clamping device 30. In the fully assembled state, a shoulder 22 of the axle journal 20 rests against an outer end face 11 of the hub 10. In this contact area, even slight relative movement can cause clicking noises, which the present invention aims to prevent. For this purpose, the fitting connection between the hub 10 and the axle journal 20 is designed as described in more detail below.

[0035] The fitting connection according to the invention is based on a toothed engagement between a toothed profile 13 on the inner circumference of the hub 10 with a toothed profile 23 on an outer circumferential section 24 of the axle journal 20.

[0036] The outer circumferential section 24 of the axle journal 20, which is provided with the toothed profile 23, is spaced from the shoulder 22 by a relief groove 25 and extends to the end face 26 of the axle journal 20.

[0037] The tooth profile 13 of the hub 10 is constant over its entire tooth length, i.e. teeth and gaps always have the same dimensions in the axial direction of the hub 10.

[0038] The axle journal 20, on the other hand, has at least a first section 27 and a second section 28 with different tooth profiles along its toothing length.

[0039] By definition, the first section 27 is located on the insertion side, i.e., further away from the shoulder 22 than the second section 28. The second section 28 is understood to be the section closer to the shoulder 22.

[0040] How Fig. As shown in Figure 2, the first section 27 has a greater axial length than the second section 28. The axial length of the first section 27 is preferably dimensioned such that the clamping device 30 can be screwed in at least 2.5 thread turns, preferably at least 3 thread turns, before the toothed profile 13 of the hub 10 engages with the second section 28.

[0041] The first section 27 has a tooth profile 23a that is constant in the longitudinal direction A of the tooth length and has clearance to the tooth profile 13 of the hub 10.

[0042] The second section 28, arranged on the shoulder side, has a tooth profile 23b with reduced tooth gaps compared to the first section 27, which is free of play to the tooth profile 13 of the hub 10.

[0043] This allows the axle journal 20 to be easily inserted into the hub 10 by hand during assembly, specifically over the area where the first section 27 engages the toothed profile 13 of the hub 10. The clamping device 30 is then actuated. In this engagement state with some play, it can be tightened by at least 2.5 thread turns. In the illustrated embodiment, this means that the fastening screw 31 engages the internal thread of the threaded opening 21 of the axle journal 20 by at least 2.5 thread turns. This ensures sufficient pull-out force for the subsequent insertion of the axle journal 20 into the hub 10, during which the toothed profile 23b of the second section 28 is pressed against the toothed profile 13 of the hub 10 by turning the fastening screw 31 or the clamping device 30.During this clamping process, the shoulder 22 ultimately comes into contact with the hub 10, so that the wheel bearing is also axially fixed at the same time.

[0044] The second section 28 with the associated tooth profile 23b is thus arranged in such a way that it can only be pressed into the hub 10 without play after the first section 27 has been inserted into the hub 10 with some play by subsequently tightening the clamping device 30 with the tooth profile 13 of the hub 10.

[0045] The backlash-free gear profile 23b of the second section 28 is obtained by plastic forming from a gear profile that is identical to the gear profile 23a of the first section 27. It is therefore possible to initially provide the entire outer circumferential section 24 with the gear profile 23a of the first section 27. The gear profile 23b of the second section 28 is then produced by post-processing this first gear profile 23a in the area of ​​the second section 28.

[0046] The production of the gear profile 23a of the first section 27 can, in principle, be carried out in any way. Preferably, however, this is done by profile rolling using a profile roller P1, as is done in Fig. 3 is indicated. The profile roller P1 is provided on its circumference with a negative profile of the tooth profile 23a of the first section 27.

[0047] The second section 28, modified with respect to the tooth profile 23b, is formed from the first tooth profile 23a by plastic forming from the outside. This can be done, for example, but is not limited to, using an untoothed roller P2.

[0048] The untoothed roller P2 can be arranged next to the profile roller P1 in a suitable manufacturing device. Preferably, at the beginning of the gear manufacturing process, it is positioned in the undercut 25 of the axle journal 20 near the shoulder 22. It is then pushed over the toothing produced by the profile roller P1 by a small axial movement of, for example, about 5 mm, and deforms the tooth tips of the gear profile 23b in the area of ​​the second section 28.

[0049] The roller P2 can be designed as a relatively slim disc to minimize the torsional length of the axle journal 20 between the shoulder 22 and the backlash-free tooth engagement on the second section 28. Optionally, two or more rollers P2 can be provided. These can preferably be arranged such that their compressive forces balance each other.

[0050] The pitch circle of the gear profile 23b of the second section 28 is reduced by 0.1 to 1.2 times the gear module of the gearing on the first section 27 compared to the pitch circle of the gear profile 23a of the first section 27 with respect to the diameter.

[0051] In a gear profile 23a with, for example, 38 teeth, a pitch circle diameter of, for example, 30.9 mm is reduced to a pitch circle diameter of 30.5 mm in the second section 28. The axial length of the second section 28 can be chosen to be quite short, approximately 2 to 5 mm, so that the post-processing effort by inward forming or embossing remains low. The untoothed disc P2 remains relatively narrow and can therefore be easily accommodated in the undercut 25.

[0052] Preferably, the inward forming or embossing takes place directly at the shoulder-side beginning of the toothing length of the axle journal 20.

[0053] Numerous variations are possible of the design variants described above.

[0054] The teeth of the gear profiles can, for example, be prismatic, trapezoidal, or have a different cross-sectional shape.

[0055] Furthermore, it is possible to superimpose an additional helical angle β onto individual sections of the gearing, as is done in Fig. 4 is indicated. This one is very small and in Fig. 4 is shown disproportionately. It preferably lies in a range of 4 to 20 arcminutes.

[0056] The superposition can be applied to the tooth profile in the longitudinal direction of the toothing on the hub 13. The tooth profile 13 remains constant, but is rotated slightly about the longitudinal direction A with increasing axial length.

[0057] Similarly, a helical angle β can also be provided on the first section 27 and / or second section 28 of the axle journal 20 in order to achieve a stronger compression fit.

[0058] The profiling of the axle journal 20 can alternatively be carried out using a rolling bar. A rolling bar is a straight bar which forms a negative contour on a working surface for producing the tooth profile. During profile rolling, the workpiece rolls along its circumference on the correspondingly profiled working surface of the rolling bar, so that the profiling of the rolling bar is transferred to the circumference of the workpiece due to the pressure exerted between the workpiece and the tool.

[0059] The invention has been explained in more detail above with reference to various embodiments and variants. These serve to demonstrate the feasibility of the invention. Individual technical features, which were explained above in the context of further individual features, can also be implemented independently of these features and in combination with further individual features, even if this is not expressly described, as long as it is technically possible. The invention is therefore expressly not limited to the specifically described embodiments, variants, and modifications, but encompasses all configurations defined by the claims. Reference symbol list 1 wheel bearing 2 Joint outer part 10 hub 11 Front face of the hub 10 13 Gear profile of the hub 10 20 axle stubs 21 Threaded opening 22 Shoulder 23 Gear profile 23a Gear profile of the first section 27 23b Gear profile of the first section 28 24 Outer circumferential section of the axle journal 20 25 Free stitch 26 End face of the axle journal 20 27 first section 28 second section 30 Clamping direction 31 Mounting screw 32 heads 40 wheel flange A Longitudinal direction of the gear length = Axial direction of the axle journal 20 P1 Profile roller P2 smooth roller (disc)

Claims

[1] Pass connection, encompassing a hub (10) with a toothed profile (13) on the inner circumference, an axle journal (20) with a toothed profile (23) on an outer circumferential section (24) and a shoulder (22) for axial support and / or contact against the hub (10), and a clamping device (30) for axially clamping the axle journal (20) to the hub (10), wherein the hub (10) has a constant tooth profile (13) over its tooth length, wherein the axle journal (20) has a first section (27) and a second section (28) with different tooth profiles (23a, 23b) along its tooth length, wherein the first section (27) is arranged on the insertion side, further away from the shoulder (22) than the second section (28) and has a constant tooth profile (23a) which has clearance with respect to the tooth profile (13) of the hub (10), and the second section (28) is arranged on the shoulder side and has a tooth profile (23b) with reduced tooth gaps compared to the first section (27), which is clearance-free with respect to the tooth profile (13) of the hub (10), and wherein the second section (28) is arranged such that it can only be pressed into the hub (10) without play after the first section (27) has been inserted into the hub (10) with some play by subsequently tightening the clamping device (30), characterized by , that the gear profile (23b) of the second section (28) is obtained by plastic forming from a gear profile corresponding to the gear profile (23a) of the first section (27), such that the tip circle of the gear profile (23b) of the second section (28) is reduced by 0.1 to 1.2 times the gear module of the first section (27) compared to the tip circle of the gear profile (23a) of the first section (27) with respect to the diameter. [2] Pass connection according to claim 1, characterized by , that the tooth profile (23b) of the second section (28) is obtained by plastic forming from the outside from a tooth profile corresponding to the tooth profile (23a) of the first section (27). [3] Pass connection according to claim 1 or 2, characterized by, that the tooth profile (13, 23, 23a, 23b) in the longitudinal direction (A) of the toothing on the hub (10) and / or on the first and / or second section (27, 28) of the axle journal (20) has a helical angle β in the range of 4 to 20 arc minutes. [4] Drive shaft and wheel bearing, wherein the wheel bearing has a hub (10) and the drive shaft has a joint outer part with an axle journal (20), and wherein the wheel bearing and the drive shaft are connected to each other by a fitting connection according to one of the preceding claims.

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