Wheel bearing assembly

Abstract

The invention relates to a wheel bearing assembly, in particular a wheel bearing assembly (1) comprising a wheel hub (10) with an inner toothing (12), a wheel bearing (20) arranged at the wheel hub, a constant-velocity joint (30) with a journal (32), wherein the journal has an outer toothing (33) which is in engagement with the inner toothing (12) of the wheel hub for torque transmission, and a clamping device (40) via which the wheel hub including the wheel bearing is clamped in this way axially against the constant-velocity joint such that a bearing inner ring (21) of the wheel bearing (20) is pressed against an abutment shoulder (34) of the constant-velocity joint (30). Between the bearing inner ring (21) and the abutment shoulder (34) there is arranged a metallic, uncoated and friction-enhanced friction ring (50) for which the coefficient of sliding friction against the contact of the bearing inner ring (21) and the abutment shoulder (34) is at least 80% of the coefficient of static friction, respectively.

Description

Technical Field

[0001] The present invention relates to a wheel bearing assembly comprising: a hub with internal teeth; a wheel bearing disposed at the hub; a constant velocity joint with a journal having external teeth that engage with the internal teeth of the hub for torque transmission; and a clamping device via which the hub, including the wheel bearing, is axially clamped against the constant velocity joint such that the inner ring of the wheel bearing is pressed against the shoulder of the constant velocity joint. Background Technology

[0002] Such wheel bearing assemblies are known, for example, from EP 3 964 726 B1. Here, the journal of the constant velocity universal joint driving the universal joint shaft (Antriebsgelenkwelle, sometimes called the active universal joint shaft) is clamped against the wheel hub, for example, by means of a screw coupling. Here, the inner ring of the wheel bearing is in a flow of axial preload. The preload must be chosen so high that the inner ring is always firmly held in its position.

[0003] However, it is also feasible to fix the inner ring of the wheel bearing to the hub, for example, by wälzennieten (sometimes called oscillating riveting). In this case, the hub section is directly supported by the constant velocity joint. In this case, the inner ring of the bearing is not under the force flow of preload. Then a lower axial preload can be selected to fasten the constant velocity joint to the hub.

[0004] In principle, the screw coupling can be positioned at the "short journal" by screwing the fixing bolt, which acts as a clamping device, into the end side of the journal, as in EP 3 964 726 B1. Figure 1 As shown in the diagram. This configuration is currently only used when the wheel bearing is under a preloaded force flow.

[0005] In contrast, "long journals" are typically used in rolled and riveted wheel hubs, which have an externally threaded section at their end, onto which a nut, serving as a clamping device, is screwed.

[0006] Torque transmission between the constant velocity universal joint and the hub is conventionally achieved via the internal and external teeth at the hub and journal. However, due to the axial preload described above, a portion of the torque is also transmitted via friction at the shoulder face of the journal. At this point, undesirable acoustic effects can occur when the torque overcomes static friction and a sudden, small relative movement occurs between the shoulder and the mating surface supporting it. This relative movement arises from the fact that torque transmission in the area of ​​tooth engagement between the internal and external teeth is almost inevitably accompanied by a certain degree of elasticity and / or clearance. The resulting noise is also known as a starting click or "bang noise."

[0007] This unwanted noise generation can occur repeatedly if slippage occurs, for example, during reverse driving (Rückwärtsfahren, sometimes called backing) or due to inertial propulsion torque (as it generates in regeneration operation in vehicles with electric drives) in the opposite direction. This problem is exacerbated by the tendency for higher wheel torque (larger wheels and / or higher motor torque) and by regeneration in vehicles with electric drives, making it virtually impossible to control using conventional measures.

[0008] As described in EP 3 964 726 B1, the following methods currently exist: 1. The first approach involves significantly increasing friction at the shoulder contact point. This is based on the consideration that slippage should no longer occur. EP 3 964 726 B1 mentions a very rough, oil-free surface, or an intermediate layer consisting of diamond wool (diamond wool) or diamond discs. However, in practice, it is often almost unavoidable to exceed static friction. The torque drop in this case is considerable. Due to the high friction value, there is also accelerated wear in the shoulder contact area. This is particularly problematic in recovery operations in the case of the short journals mentioned above, because as wear increases, the preload at the wheel bearing decreases, which may ultimately jeopardize the reliability of the entire helical coupling.

[0009] 2. The second method involves reducing friction at the shoulder contact point to such an extent that noise is eliminated during slippage. This can be achieved, for example, by using a friction-reducing sliding disc as an intermediate layer, as suggested in EP 1 526 297 A1, EP2 263 887 A1, and JP 2003 097588 A. Reducing friction decreases the share of torque transmitted via the shoulder contact point at the constant velocity universal joint. This torque share must therefore be additionally guided via the internal and external teeth between the hub and journal. This necessitates corresponding reinforcement of the journal and hub. This, in turn, implies a larger and heavier design with a larger diameter journal and / or an increase in the axial length of the toothed engagement. In both cases, this results in additional structural space requirements and increased component weight, which is also disadvantageous.

[0010] Long journals are generally preferred because, unlike short journals, they can be made of solid material and remain more compact. Furthermore, the use of rolled-riveted wheel bearings allows for lower requirements on the reliability of the helical joint. Axial forces can be kept lower because the wheel bearings do not need to be reliably preloaded together, resulting in lower torque at the eventual slippage and consequently lower noise. This, in turn, allows the use of coated sliding discs. However, for short journals, sliding discs are not a satisfactory solution under torsional alternating loads, as significantly higher axial preload is required in such cases.

[0011] 3. The third method involves implementing a seamless fit between the hub and journal, ensuring that loosening of the components and consequent impact are no longer possible. This can be achieved, for example, by bonding, however this incurs additional costs during assembly and in customer service situations (sometimes referred to as after-sales service), and can also be achieved by pushing in the teeth. EP 3 964 726 B1 proposes a special tooth geometry for this purpose to achieve high pushing while considering economic suitability for mass production, and yet ensuring that the components can be engaged manually, i.e., without additional pushing devices. However, in cases of high recovery torque, the latter may be insufficient to prevent the generation of interfering noise. Summary of the Invention

[0012] In this context, the present invention is based on the objective of providing a solution that allows for the reduction of unwanted noise formation in situations involving high torsional alternating loads and high axial preload in wheel bearing assemblies.

[0013] This task is solved by a wheel bearing assembly with the features described below. The wheel bearing assembly according to the invention is particularly outstanding in that a metallic, uncoated, and friction-enhancing friction ring is arranged between the inner bearing ring and the shoulder, wherein the coefficient of sliding friction is at least 80% of the coefficient of static friction for contact between the friction ring and the inner bearing ring and the shoulder.

[0014] The use of metal, uncoated friction rings allows for high axial force preload on the wheel bearing assembly at a level that ensures sufficient reliability of the helical engagement while simultaneously preloading the wheel bearing.

[0015] If the coefficients of sliding friction and static friction vary at similar levels, the torque drop during the transition from static friction to sliding friction (i.e., slippage) remains low. Therefore, the share of torque transmitted via the shoulder changes less, resulting in lower additional costs for reinforcement in the areas of the internal and external gears. This is particularly advantageous for compact designs and the use of short journals.

[0016] Furthermore, this reduces noise generation despite the high axial preload. The exact "bang noise" is avoided or at least reduced to a soft, low-frequency clicking sound, making it virtually imperceptible.

[0017] Therefore, the solution according to the invention is particularly suitable for vehicles with high wheel torque and / or regeneration, as is the case, especially in electric vehicles.

[0018] The static friction coefficient is preferably higher than that for steel-to-steel friction. Correspondingly, in the case of dry friction, the static friction coefficient is preferably greater than 0.15 and less than 0.30. However, excessively high friction values ​​should be avoided, as this may lead to accelerated wear in slippage situations, which will eventually result in an undesirable decrease in preload over time.

[0019] According to another specific embodiment of the invention, the torque transmitted through the friction ring accounts for 20% to 40% of the total torque transmitted between the hub and the constant velocity joint. This is advantageous for a compact and lightweight design, and is not achievable, for example, using anti-friction sliding discs. Currently, "torque to be transmitted" is understood as the maximum torque that can be transmitted at the wheel (also known as slip torque, which depends on the shaft load, including shaft load displacement). Dynamic effects in the drive system can lead to sudden, high load peaks, however, which do not currently fall under the definition of "torque to be transmitted." According to another specific embodiment of the invention, the friction ring has a tensile strength of 500 to 650 N / mm² and / or a hardness of 140 to 230 HV10. This enables high axial preload with forces exceeding 100 kN.

[0020] Nevertheless, the manufacture and assembly of friction rings remain extremely simple. For example, friction rings can be constructed from sheet metal stampings at a particularly cost-effective cost.

[0021] With a preferred thickness of 0.2 to 2.0 mm, the friction ring does not affect structural space requirements or the mass of the wheel bearing assembly. Instead, as mentioned above, the friction ring allows for a compact and lightweight design of the wheel bearing assembly in the journal area.

[0022] According to another specific implementation, the friction ring can be made of a copper alloy. Here, copper alloys with a tin content of 2% to 8% have proven particularly advantageous.

[0023] For ease of assembly, the friction ring may have an annular section with multiple bridging portions protruding radially inward from the inner circumference of the annular section, wherein the friction ring generally extends in a plane.

[0024] According to another specific embodiment of the invention, the internal and external teeth at the hub and journal are formed by backlash-free adapting teeth (Passverzahnung, sometimes referred to as adapting engagement), wherein the clamping device is a clamping bolt that is axially screwed into an internally threaded hole constructed at the journal via a threaded section, and the clamping bolt is supported at the hub by a head section. This short journal enables a particularly compact form of the wheel bearing assembly, with high torque transmission potential (especially even under alternating loads) and suitable acoustic performance.

[0025] For example, gapless fitting teeth can be obtained by pressing the internal and external teeth together with an axial pulling force during assembly. Attached Figure Description

[0026] The present invention will now be explained in more detail with reference to the embodiments presented in the accompanying drawings. Drawings: exist Figure 1 The figure shows a longitudinal sectional view of a wheel bearing assembly with a friction ring according to an embodiment of the present invention, and exist Figure 2 The image shows a view of the friction ring. Detailed Implementation

[0027] Figure 1 and Figure 2 A feasible embodiment for carrying out the present invention is shown.

[0028] An exemplary wheel bearing assembly 1 includes a wheel hub 10, a wheel bearing 20 disposed at the wheel hub 10, a constant velocity universal joint 30 as part of a drive shaft, and additionally a clamping device 40 and a friction ring 50.

[0029] Wheel bearing assembly 1 is preferably used in passenger cars and light commercial vehicles.

[0030] The hub 10 currently has a through hole 11 with internal teeth 12. The internal teeth 12 can be implemented, for example, as sawtooth teeth, splined shaft teeth, gear shaft teeth, etc.

[0031] Furthermore, the hub 10 has a shoulder 13 on its outer circumference for accommodating the wheel bearing 20. The wheel bearing 20 is seated on the shoulder 13 by means of the bearing inner ring 21. Figure 1 As illustrated in the example, a portion of the bearing inner ring can also be provided directly through a section of the hub 10.

[0032] The constant velocity universal joint 30 currently has a universal joint bell cover 31 and a journal 32 axially connected thereto. An external tooth 33 is constructed at the journal 32, which engages with the internal tooth 12 of the hub 10 for torque transmission.

[0033] The tooth engagement between the internal tooth portion 12 and the external tooth portion 33 is preferably constructed without gaps. For this purpose, for example, the internal tooth portion 12 and the external tooth portion 33 can be axially pressed together.

[0034] In particular, such toothed engagement can be implemented, for example, as described in EP 3 964 726 B1, but the invention is not limited thereto.

[0035] With the help of the clamping device 40, the wheel hub 10, including the wheel bearing 20, is axially clamped against the constant velocity universal joint 30, that is, the inner ring 21 of the wheel bearing 20 is pushed against the abutment shoulder 34 of the constant velocity universal joint 30.

[0036] like Figure 1 As exemplarily presented, the clamping device 40 can be implemented as a clamping bolt that is axially screwed into an externally threaded section 41 into an internally threaded section 35 constructed at the journal 32. The internally threaded section 35 can be constructed at the through hole of the constant velocity universal joint 30.

[0037] The clamping bolt may also have a head section 42 that is axially supported at the hub 10.

[0038] In addition, the clamping bolt may optionally have an expansion section 43 with a cross-section that tapers relative to the external thread section 41, through which the external thread section 41 transitions into the head section 42.

[0039] Due to the internal thread section 35, Figure 1 The journal 32 in the middle can also be called a short journal. This "short journal" is shorter than the so-called "long journal". In the "long journal", the journal with external teeth is usually formed of solid material and additionally has an axially connected external thread section for the nut as a clamping device.

[0040] The axial end of the bearing inner ring 21 does not directly abut against the shoulder 34 of the constant velocity joint 30. Instead, a friction ring 50 is added between them such that the friction ring 50 and the wheel bearing 20 are in the force flow of the axial preload provided by the clamping device 40. Therefore, the axial preload 40 of the wheel bearing 20 is supported at the shoulder 34 of the constant velocity joint 30 via the friction ring 50.

[0041] As described above, the friction ring 50 is a metal component without a coating, which increases friction compared to the bearing inner ring 21 directly abutting the shoulder 34. Accordingly, the static friction coefficient between the friction ring 50 and the abutting surfaces of the components 21 and 34 is higher than the static friction coefficient between the bearing ring 21 and the shoulder 34.

[0042] In particular, the static friction coefficient in the case of contact friction ring 50 is greater than the static friction coefficient for contact between steel and steel.

[0043] The friction ring 50 ensures that a limited share of the total torque is transmitted via the friction ring 50 and therefore via the shoulder 34 in the torque transmission from the constant velocity universal joint 30 to the hub 10 or in the opposite direction.

[0044] Preferably, the torque transmitted via the friction ring 50 accounts for 20% to 40% of the total torque transmitted between the hub 10 and the constant velocity joint 30. Preferably, the lower limit is greater than 25% and / or the upper limit is less than 35%. During fully loaded acceleration, before the wheels slip on the road, the torque that can be transmitted at the wheels at the rear axle of the passenger car due to axle load displacement can be, for example, about 3000 Nm.

[0045] According to the invention, the coefficient of sliding friction for the friction pair formed by the friction ring 50 and the abutment shoulder 34, and for the friction pair formed by the friction ring 50 and the abutment surface at the bearing inner ring 21, is at least 80% of the coefficient of static friction of the respective friction pair. Preferably, the coefficient of sliding friction is greater than 86% of the coefficient of static friction, and more preferably, even greater than 90% of the coefficient of static friction.

[0046] In particular, the sliding friction coefficient of the friction ring 50 against the steel can be at least 80% of the static friction coefficient of the steel, preferably at least 86% of the static friction coefficient of the steel, and even more preferably greater than 90% of the static friction coefficient of the steel.

[0047] In the case of dry friction, the static friction coefficient is preferably greater than 0.15 and less than 0.30. Preferably, the lower limit is also greater than 0.16 or greater than 0.17. Preferably, the upper limit is also less than 0.28 or less than 0.25.

[0048] If we assume that the static friction coefficient for dry friction, where steel is against steel, is 0.15, then the sliding friction coefficient for this type of friction pair is typically about 0.12, which is at most 80% of the static friction coefficient.

[0049] In contrast, the friction ring 50 according to the invention can achieve, for example, a static friction coefficient of 0.19 against steel and a sliding friction coefficient of 0.18 against steel.

[0050] Therefore, when using friction ring 50, the difference between sliding friction and static friction is significantly smaller compared to steel-to-steel friction pairs. However, the friction level is higher not only for the sliding friction coefficient but also for the static friction coefficient compared to steel-to-steel friction pairs.

[0051] This results in the portion of torque transmitted via the shoulder 34 not being significantly reduced when static friction is overcome. Therefore, compared to cases with a stronger difference between the static and sliding friction coefficients, or even compared to using a sliding disc instead of the friction ring 50, the journal 32 and the teeth between the hub 10 and the journal 32 do not need to be correspondingly strongly reinforced. This allows for a more compact and lighter design for the wheel bearing assembly.

[0052] The reduced torque also has a positive impact on the potential noise generation during the transition from static friction to sliding friction. The corresponding "bang noise" either disappears completely or becomes so weak that it is almost imperceptible.

[0053] In order to support large axial forces, as particularly in the case of short journals (in which the wheel bearing 20 and friction ring 50 are located in the force flow of the axial preload of the clamping device 40), the friction ring 50 preferably has a tensile strength of 500 to 650 N / mm² and / or a hardness of 140 to 230 HV10.

[0054] In particular, the axial force of 100 to 250 kN (as required for the preload of the wheel bearing 20) is supported by the friction ring 50 without compromising the reliability of the helical joint.

[0055] In addition, high wear resistance is ensured to guarantee the reliability of the helical engagement and the maintenance of preload throughout the service life of the wheel bearing assembly.

[0056] Friction ring 50 (which is in) Figure 2 (Exemplary examples are presented in more detail below) For example, it can be constructed as a sheet metal stamping, the thickness of which is preferably in the range of 0.2 to 2.0 mm, and more preferably 0.3 to 0.7 mm. The friction ring 50 can thus be manufactured very simply and cost-effectively.

[0057] For ease of assembly, the friction ring 50 may have an annular section 51, wherein a plurality of bridging portions 52 protrude radially inward from the inner circumference of the annular section 51. The bridging portions 52 are used to hold the annular section 51 of the friction ring 50 at a height between the corresponding mating surfaces of the abutment shoulder 34 and the inner bearing ring 21 during assembly.

[0058] Preferably, the entire friction ring 50 is constructed such that it extends generally in a plane, i.e., it remains a flat, disc-shaped member.

[0059] In one implementation variation, the friction ring 50 is made of a copper alloy, which preferably has a tin content of 2% to 8%. No possible cladding or surface treatment is required on the rolled sheet.

[0060] As a non-limiting example of the material, a rolled sheet of CuSn6 H180 with a sheet thickness of 0.5 mm is mentioned.

[0061] In a modified embodiment, the friction ring 50 of the type mentioned above can also be used in conjunction with a long journal and / or with a rolled riveted wheel bearing. In the case of the rolled riveted wheel bearing mentioned later, the friction ring 50 is not abutted against the inner ring of the wheel bearing 20, but against the wall section of the hub 10.

[0062] The invention has been explained in more detail above with reference to embodiments and other modifications. In particular, individual technical features (which are explained above in the context of other individual features) may be implemented independently of or in combination with other individual features, even if not explicitly described, provided that it is technically feasible. Therefore, the invention is explicitly not limited to the described embodiments and modifications, but includes all designs defined by the patent claims.

[0063] Reference number list 1. Wheel bearing assembly 10-inch wheels 11 Through Holes 12 Internal teeth 13 shoulder 20 wheel bearings 21 Bearing inner ring 30 constant velocity universal joint 31 Universal joint bell cover 32 journals 33 External teeth 34. Lean against the shoulder 35 Internal thread section 40 Clamping device 41 External thread section 42 Head section 43 Expansion Section 50 Friction Ring 51. Circular Section 52 Bridging section

Claims

1. A wheel bearing assembly (1), comprising: The wheel hub (10) has internal teeth (12). Wheel bearing (20), which is arranged at the wheel hub (10), A constant velocity universal joint (30) having a journal (32) having an external toothed portion (33) that engages with an internal toothed portion (12) of the hub (10) for torque transmission, and A clamping device (40) clamps the hub (10), including the wheel bearing (20), axially against the constant velocity joint (30), such that the inner ring (21) of the wheel bearing (20) is pressed against the shoulder (34) of the constant velocity joint (30). Its features are, A metallic, uncoated, and friction-enhancing friction ring (50) is arranged between the inner bearing ring (21) and the abutment shoulder (34), wherein the sliding friction coefficient is at least 80% of the static friction coefficient for the contact between the friction ring and the inner bearing ring (21) and the abutment shoulder (34).

2. The wheel bearing assembly (1) according to claim 1, characterized in that, In the case of dry friction, the static friction coefficient is greater than 0.15 and less than 0.

30.

3. The wheel bearing assembly (1) according to claim 1 or 2, characterized in that, The torque transmitted via the friction ring (50) accounts for 20% to 40% of the total torque transmitted between the hub (10) and the constant velocity universal joint.

4. The wheel bearing assembly (1) according to any one of claims 1 to 3, characterized in that, The friction ring (50) has a tensile strength of 500 to 650 N / mm² and / or a hardness of 160 to 230 HV10.

5. The wheel bearing assembly (1) according to any one of claims 1 to 4, characterized in that, The friction ring (50) is a sheet metal stamping part.

6. The wheel bearing assembly (1) according to any one of claims 1 to 5, characterized in that, The friction ring (50) has a thickness of 0.2 to 2.0 mm.

7. The wheel bearing assembly (1) according to any one of claims 1 to 6, characterized in that, The friction ring (50) is made of copper alloy.

8. The wheel bearing assembly (1) according to claim 7, characterized in that, The copper alloy has a tin content of 2% to 8%.

9. The wheel bearing assembly (1) according to any one of claims 1 to 8, characterized in that, The friction ring (50) has an annular section (51) in which a plurality of bridging portions (52) protrude radially inward from the inner circumference of the annular section (51), and wherein the friction ring (50) generally extends in a plane.

10. The wheel bearing assembly (1) according to any one of claims 1 to 9, characterized in that, The internal and external teeth (12, 33) are formed by mating teeth without gaps, and / or the clamping device (40) is a clamping bolt that is axially screwed into the internal thread section (35) constructed at the journal (32) by means of an external thread section (41), and the clamping bolt is supported at the hub (10) by means of a head section (42).

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