Driven four-link rear axle for a motor vehicle

Description

[0001] The invention relates to a driven four-link rear axle for a motor vehicle according to the preamble of claim 1.

[0002] Such a driven four-link rear axle is known from DE 10 2004 060 589 A1.

[0003] Other driven four-link rear axles are known from DE 10 2010 021 215 A1 and CN 106 515 332 A.

[0004] Based on this, the invention aims to achieve better space utilization on a motor vehicle while maintaining the axle principle of a driven four-link rear axle and a large loading width.

[0005] Four-link rear axles are already well-known in various designs for vehicles with non-driven rear axles. However, with a driven rear axle, the problem arises of accommodating the driveshaft required for the drive within the wheel suspension area, meaning that wheel suspension configurations for non-driven rear axles are generally unsuitable for driven rear axles.

[0006] The aforementioned problem is solved by a driven four-link rear axle according to claim 1.

[0007] This allows all components for supporting and driving the vehicle wheel to be arranged below a loading floor in a passenger vehicle, resulting in a particularly large loading width and thus a larger trunk volume in a motor vehicle compared to conventional damper arrangements.

[0008] Nevertheless, collisions between the wheel-guiding control arms on the one hand and the vibration damper and the drive shaft on the other hand are avoided when the corresponding rear axle wheel compresses and rebounds.

[0009] Furthermore, the inclination of the vibration damper promotes a progressive damping ratio, i.e., a damping ratio that increases with increasing suspension travel. Accordingly, the effect of the vibration damper increases over the suspension travel.

[0010] The direct connection of the vibration damper to the wheel carrier allows, compared to DE 10 2010 021 215 A1, a larger and therefore better travel ratio, resulting in better responsiveness and improved comfort.

[0011] By tilting the vibration damper inwards in the transverse direction of the vehicle, whereby in the installation rest position the angle of inclination to the vertical in the transverse direction of the vehicle is in a range of 20° to 30°, a particularly favorable utilization of the available installation space results.

[0012] The arrangement of the wheel-side attachment point within the rim of the vehicle wheel allows for a relatively large axial length of the vibration damper with corresponding damping capacity.

[0013] By positioning the wheel-side attachment point of the front lower control arm outside the rim of the vehicle wheel, more space is available inside the rim for the vibration damper.

[0014] Specific embodiments of the invention are the subject of further patent claims.

[0015] For example, the vibration damper can be coupled laterally, i.e., on the outside of the vehicle, to a longitudinal member of the vehicle body via its body-side mounting point. This allows for space-saving installation and easy mounting.

[0016] Furthermore, the body-side connection point of the vibration damper can be located below the height of the vehicle floor, so that the loading width is not affected by the vibration damper.

[0017] In this sense, the wheel-side mounting point of the vibration damper can also be coupled lower on the wheel carrier in relation to the vertical direction than a wheel-side mounting point of the front lower control arm.

[0018] According to another embodiment of the invention, the vibration damper can be inclined more strongly in the direction of travel than in the transverse direction of the vehicle.

[0019] With regard to improved lateral and longitudinal force steering, it is also advantageous to position the vehicle body-side attachment point of the front lower control arm in the direction of travel in front of its attachment point on the wheel carrier.

[0020] The invention will now be explained in more detail with reference to an embodiment illustrated in the drawing. The drawing shows: Figure 1: A spatial view of an embodiment for a driven four-link rear axle of a motor vehicle. Figure 2: A side view of the rear axle according to... Figure 1 To illustrate the alignment of the vibration damper, Figure 3 shows a side view of the rear axle according to Figure 1 To illustrate the position of a virtual steering axis, Figure 4 shows a top view of the rear axle according to Figure 1 , and in Figure 5 a rear view of the rear axle according to Figure 1 .

[0021] The figures show an example of a driven four-link rear axle 1 for a passenger car.

[0022] The driven four-link rear axle 1 comprises, on each side of the wheel, a wheel carrier 2, a longitudinal control arm 3, an upper control arm 4, a front lower control arm 5 and a rear lower control arm 6 for supporting the wheel carrier 2 on the vehicle body side. Furthermore, a driveshaft 7 for transmitting a drive torque to a vehicle wheel 8 rotatably mounted on the wheel carrier 2 and a vibration damper 9 are provided.

[0023] The longitudinal control arm 3, which runs predominantly in the direction of travel F, is elastically coupled to a vehicle body by means of a rubber-metal bearing 10, so that the longitudinal control arm 3 can pivot about an axis of rotation that runs essentially in the transverse direction Q of the vehicle. Furthermore, the longitudinal control arm 3 is rigidly coupled to the wheel carrier 2, shown here by way of example by means of two bolts. However, it is also possible to make an elastic coupling at this point using two rubber-metal bearings or alternatively to form the wheel carrier 2 integrally with the longitudinal control arm 3.

[0024] The upper control arm 4 is coupled to the wheel carrier 2 and a subframe 11 of the vehicle body in the direction of travel F and above the center of the vehicle wheel 7 (hereinafter referred to as wheel center M). The coupling can be made on both sides via rubber-elastic bearings. Preferably, the connection point O2 on the wheel carrier 2 is located slightly forward of the connection point O1 on the vehicle body (in this case, the subframe 11) in the direction of travel F, in order to enable improved lateral force steering.

[0025] Furthermore, the wheel-side connection point O2 is located above a lower end section of the vibration damper 9, which is inclined in the direction of travel F. It is not possible to move the wheel-side connection point O2 on the wheel carrier 2 in the direction of travel, as otherwise the upper control arm 4 would collide with the vibration damper 9 when the vehicle wheel 8 compresses and rebounds, which must be avoided.

[0026] The upper control arm 4 of the exemplary embodiment is provided with a bend 13 to allow it to pass under a longitudinal member 12 of the vehicle body. By limiting the bend of the control arm 4 to a single plane, it can be used uniformly for both the left and right sides of the vehicle. This keeps manufacturing and assembly costs low. However, due to the driveshaft 6, the body-side attachment point O1 of the upper control arm 4 cannot be moved further rearward against the direction of travel F.

[0027] In a modification of the embodiment, a two-dimensionally cranked upper control arm 4 is used, the body-side attachment point O1 of which lies behind the driveshaft 7 in the direction of travel. This enables further improved lateral force steering.

[0028] The front lower control arm 5 is coupled to the wheel carrier 2 in the direction of travel F in front of and below the wheel center M. Preferably, the coupling is elastic, for example by means of a rubber-metal bearing. The corresponding wheel-side connection point S2 is preferably located outside the rim of the vehicle wheel 8. Furthermore, the front lower control arm 5 is coupled to the vehicle body, preferably to the subframe 11 arranged thereon. Preferably, this coupling is also elastic, for example by means of a rubber-metal bearing.

[0029] The body-side mounting point S1 of the front lower control arm 5 is preferably located in front of the wheel-side mounting point S2 when viewed in the direction of travel F, in order to enable improved lateral steering in the sense of a toe-in effect under lateral and longitudinal steering forces. In particular, an angle of attack to the vehicle's transverse direction Q in the range of 5° to 30° can be provided in a resting installation position in the FQ plane. In addition, the front lower control arm 5 preferably runs substantially horizontally.

[0030] The front lower wishbone 5 can in particular be designed as a rod-shaped link or tie rod with exactly one wheel-side attachment point S2 and exactly one body-side attachment point S1.

[0031] The rear lower control arm 6 is coupled to the wheel carrier 2 behind and below the wheel center M in the direction of travel F. The corresponding wheel-side connection point is marked U4 in the figures. Likewise, the rear lower control arm 6 is coupled to the vehicle body, in this case to the subframe 11, behind and below the wheel center in the direction of travel F. The corresponding body-side connection point is marked U3 in the figures. The coupling can be elastic on both sides, for example, again via a rubber-metal bearing.

[0032] How in particular Figure 4 As can be seen, the rear lower control arm 6 runs in the direction of travel F behind the drive shaft 7 predominantly in the transverse direction of the vehicle Q.

[0033] The wheel-side mounting point U4 of the rear lower control arm 6 is preferably located as close as possible to the body-side mounting point U3 when viewed from the outside of the vehicle in the direction of travel F. In particular, an angle of attack opposite to the vehicle's transverse direction Q in the range of 5° to 10° can be provided in a resting installation position in the FQ plane.

[0034] In the illustrated embodiment, the rear lower control arm 6 is designed as a spring link, which supports a suspension spring 14. In this example, the latter is shown as a coil spring, which connects to the vehicle body via a spring mount 15. An auxiliary spring 16 can be arranged within the coil spring to create a progressive wheel load curve. The spring mount 15 also supports the auxiliary spring 16 against the vehicle body.

[0035] The vibration damper 9 engages the wheel carrier 2 below and in the direction of travel F in front of the wheel center M. It runs in the direction of travel F in front of the driveshaft 7 and between the front lower control arm 5 and the upper control arm 4, inclined in the direction of travel F towards a body-side attachment point DO. In its rest position, the angle of inclination to the vertical in the direction of travel F, i.e., in a plane of travel F, is between 20° and 60°. Furthermore, the body-side attachment point DO of the vibration damper 9 is located within the height of the vehicle wheel 8.

[0036] The vibration damper 9 is coupled to the wheel carrier 2 behind the front lower control arm 4, viewed in the direction of travel F. The corresponding lower connection point of the vibration damper 9 is labelled DU in the figures. Viewed in the direction of travel F, this point is located in front of and below the wheel center M in an area within the rim of the vehicle wheel 8.

[0037] The wheel-side mounting point DU of the vibration damper 9 is located lower on the wheel carrier 2 with respect to the vertical direction V than the wheel-side mounting point S2 of the front lower control arm 4.

[0038] In the transverse direction of the vehicle, point DU is located further away from a longitudinal center axis of the vehicle than point S2.

[0039] The coupling of the vibration damper 9 to the wheel carrier 2 is preferably elastic.

[0040] As already mentioned, the vibration damper is inclined diagonally forwards when viewed in the direction of travel F. Furthermore, as shown in Figure 5 It is clearly visible that an additional inclination in the transverse direction Q towards the vehicle center is provided. The corresponding inclination angle to the vertical V in the transverse direction Q, i.e., in the QV plane, lies in a range of 20 to 30°.

[0041] Preferably, the vibration damper 9 is inclined more strongly in the direction of travel F than in the transverse direction of the vehicle Q.

[0042] The body-side mounting point DO of the vibration damper 9 is preferably elastically mounted and is located in an area below the top of the tire. In other words, the body-side mounting point DO of the vibration damper 9 is located in the rear axle 1's rest position with respect to the vertical direction V in an area within the height of the vehicle wheel 8.

[0043] The vibration damper 9 is preferably attached to the vehicle body below the level of the vehicle floor and preferably on the outside of the longitudinal member 12.

[0044] Due to the location of the body-side attachment point DO or a corresponding bearing laterally, namely on the outside of the vehicle on the longitudinal member 12, fastening, for example screwing from the outside to screw points 17 of a damper bearing is possible in a simple way.

[0045] To prevent the vehicle wheel 8 from being pushed towards toe-out due to the damping forces during compression, which would result in undesirable oversteer, the damper axis A, which runs through the body-side and wheel-side mounting points DO and DU of the vibration damper 9, is aligned such that its extension meets the road surface behind the wheel contact point RA. This contact point is located in Figure 2 The contact point RA is designated DA. Without any caster, the wheel contact point RA is located vertically below the wheel center M. On a moving vehicle, the contact point RA can shift slightly rearward due to the tire caster when moving in the direction of travel F. Even in this case, the contact point DA, viewed in the direction of travel F, lies behind the contact point RA.

[0046] This means that if one also includes the inclination of the vibration damper 9 in the vehicle transverse direction Q, which is in the Figure 2 and 4The distances AX and AY of the impact point DA from the wheel contact point RA in the direction of travel F and in the transverse direction of the vehicle Q shown always have and retain the same sign in all compression and rebound states of the rear axle 1.

[0047] With respect to the upper control arm 4, the vibration damper 9 is arranged in front of the upper control arm 4 in the direction of travel F. The wheel-side mounting point O2 of the upper control arm 4, when viewed in the QF plane, is located approximately above the wheel-side mounting point DU of the vibration damper 9 or possibly slightly behind it.

[0048] Furthermore, the driveshaft 7 is located behind the vibration damper 9 and the upper control arm 4 in the direction of travel.

[0049] A stabilizer 18 can, for example, be directly coupled to the wheel carrier 2 by means of a connecting rod 19. From its coupling point on the connecting rod 19, it initially extends forward in the direction of travel F and is then angled in the transverse direction Q of the vehicle. The stabilizer 18 is mounted in a stabilizer bearing 20, which is fixed to the vehicle body, in this case to the subframe 11.

[0050] In one embodiment, without limitation, a drive unit for driving the cardan shaft 7 is arranged on the subframe 11, preferably elastically mounted thereon. The drive unit can, for example, be an electric motor.

[0051] The four-link rear axle configuration described above results in a virtual, i.e., imaginary, steering axis L, as described in Figure 3This is shown. In this case, the steering axis always intersects the road surface behind the wheel contact point RA at point LA. This ensures that the vehicle wheel 8 moves in the direction of toe-in under the influence of lateral forces. The position of the virtual steering axis LA is primarily determined by the arrangement of the control arms 4, 5, and 6. In contrast, the influence of the stiffness of the rubber-metal bearings used at the attachment points of these control arms is less significant.

[0052] The arrangement of the vibration damper 9 described above, in particular its inclination and the arrangement of the lower attachment point DU as far away as possible from the longitudinal center axis of the vehicle and preferably within the rim of the vehicle wheel 8, results in a compact package without affecting the ground clearance of the vehicle.

[0053] At the same time, this makes it possible to position the upper body-side connection point DO of the vibration damper 9 as close as possible to the roadway, thereby achieving a large loading width on the vehicle.

[0054] Moreover, the arrangement described above allows for a progressive damper ratio, i.e., the damper ratio increases with increasing compression of the respective vehicle wheel 8. This has the advantage that the effect of the vibration damper 9 also increases with increasing compression travel.

[0055] The inclination of the vibration damper also promotes toe-in steering due to damping forces during compression.

[0056] The invention has been explained in more detail above with reference to various embodiments and further modifications. These serve to demonstrate the feasibility of the invention. Individual technical features, which were explained above in the context of other individual features, can also be implemented independently of these features and in combination with other 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, but encompasses all configurations defined by the claims. 1 Four-link rear axle 2 Wheel carrier 3 Trailing arm 4 Upper control arm 5 Front lower control arm 6 Rear lower control arm 7 Driveshaft 8 Vehicle wheel 9 Shock absorber 10 Rubber-metal bearing 11 Subframe (vehicle body) 12 Longitudinal member of the vehicle body 13 Crank link 14 Body spring 15 Spring mount 16 Auxiliary spring 17 Bolt point upper shock mount 18 Stabilizer bar 19 Stabilizer link 20 Stabilizer bar bearing A Shock absorber axle AX Distance DA to RA in the direction of travel F AY Distance DA to RA in the lateral direction of the vehicle Q DA Point of contact of shock absorber axle with road surface DO Body-side mounting point of the shock absorber DU Wheel-side mounting point of the shock absorber F Direction of travel (forward) L Virtual (imaginary) steering axis LA Point of contact of virtual steering axis with road surface M Wheel center O1 Body-side mounting point of the upper control arm 4 O2 Wheel-side mounting point of the upper control arm 4 Q Vehicle transverse direction RA Wheel contact point S1 Body-side mounting point of the front lower control arm 5 S2 Wheel-sideFront lower control arm mounting point 5 U3 Body-side mounting point of the rear lower control arm 6 U4 Wheel-side mounting point of the rear lower control arm 6 V Vertical direction

Claims

1. Driven four-link rear axle (1) for a motor vehicle, comprising: a stub axle (2) on which a vehicle wheel (8) is rotatably mounted, a longitudinal link (3), an upper transverse link (4) and two lower transverse links (5, 6) for supporting the stub axle (2) on the vehicle body side, a cardan shaft (7) for transmitting a drive torque to the vehicle wheel (8) rotatably mounted on the stub axle (2), and a vibration damper (9) which engages the stub axle (2) with a wheel-side connection point (DU) below the wheel center (M) and extends in front of the cardan shaft (7) and between a front link of the lower transverse links (5) and the upper transverse link (4) in the direction of travel (F) at an inclination to a body-side engagement point (DO), wherein, in the installed rest position, the corresponding angle of inclination to the vertical (V) in the direction of travel (F) is in the range of 20° to 60° and the body-side connection point (DO) of the vibration damper (9) is within the height of the vehicle wheel (8), characterized in that the vibration damper (9) engages the stub axle (2) in front of the wheel center (M) in the direction of travel (F); the vibration damper (9) is inclined inwards in the vehicle transverse direction (Q), wherein, in the installed rest position, the angle of inclination to the vertical (V) in the vehicle transverse direction (Q) is in a range of 20 to 30°, the wheel-side connection point (DU) of the vibration damper is arranged within a rim of the vehicle wheel (8) and the wheel-side connection point (S2) of the front lower transverse link (5) is located outside the rim of the vehicle wheel (8), and an impact point (DA) of the axis (A) of the vibration damper (9), which runs through the body-side and wheel-side connection points (DO, DU) of the vibration damper (9), is offset in the vehicle transverse direction by a positive distance (AY) from the wheel contact point (RA) towards the outside of the vehicle and in the vehicle longitudinal direction by a positive distance (AX) from the wheel contact point (RA) against the direction of travel, these distances (AX, AY) always having and retaining the same sign in all compression and rebound states of the rear axle (1).

2. Driven four-link rear axle (1) for a motor vehicle according to claim 1, characterized in that the vibration damper (9) is coupled with its body-side connection point (DO) laterally, namely on the outside of the vehicle, to a longitudinal member (12) of a vehicle body.

3. Driven four-link rear axle (1) for a motor vehicle according to claim 1 or 2, characterized in that the body-side connection point (DO) of the vibration damper (9) is arranged below a vehicle floor of the motor vehicle.

4. Driven four-link rear axle (1) for a motor vehicle according to any of claims 1 to 3, characterized in that the wheel-side connection point (DU) of the vibration damper (9) is coupled to the stub axle (2) lower in relation to the vertical direction (V) than a wheel-side connection point (S2) of the front lower transverse link (5).

5. Driven four-link rear axle (1) for a motor vehicle according to any of claims 1 to 4, characterized in that the vibration damper (9) is inclined more in the direction of travel (F) than in the vehicle transverse direction (Q).

6. Driven four-link rear axle (1) for a motor vehicle according to any of claims 1 to 5, characterized in that a stabilizer (18) is coupled directly to the stub axle (2) by means of a coupling rod (19).

7. Driven four-link rear axle (1) for a motor vehicle according to claim 6, characterized in that the stabilizer (18) initially extends forward in the direction of travel F from its coupling point to the coupling rod (19) and is then angled in the vehicle transverse direction Q.