DE102021208301B3 - Motor vehicle wheel suspension with a leaf spring device on each wheel side - Google Patents

Abstract

A motor vehicle wheel suspension (1) has a leaf spring device (10) on each wheel side. The leaf spring device (10) comprises a first leaf spring (11) made of fibre-reinforced plastic and a second leaf spring (12) made of fibre-reinforced plastic, the first leaf spring (11) and the second leaf spring (12) each having a first end (11a, 12a ) are brought together to form a V-shaped structure. Furthermore, a first fastening device (13) is provided for pivotable vehicle body-side support, which receives the brought together first ends (11a, 12a) of the first and second leaf springs (11, 12). An externally powered drive device (16), by means of which the first fastening device (13) can be pivoted, acts on the first fastening device (13).

Description

The invention relates to a motor vehicle wheel suspension with a leaf spring device on each side of the wheel, each leaf spring device comprising: a first leaf spring made of fiber-reinforced plastic, a second leaf spring made of fiber-reinforced plastic, the first leaf spring and the second leaf spring being brought together at a respective first end, to form a V-shaped structure, and first attachment means for pivotally supporting the vehicle body side, which receives the joined first ends of the first and second leaf springs.

Generic motor vehicle wheel suspensions are out DE 10 2016 220 325 A1 and DE 10 2018 206 023 A1 famous. The leaf spring devices on both wheel sides point towards one another with the tips of their V-shape, resulting in an X-shaped spring structure when viewed in the longitudinal direction of the vehicle, the second leaf springs being arranged vertically above the first leaf springs. The first leaf springs, which are at the bottom in the installed position, are each coupled with a second end to a wheel carrier, while the second leaf springs, which are at the top in the installed position, are supported on the vehicle body side. During DE 10 2016 220 325 A1 specifies the basic form of such a motor vehicle wheel suspension, disclosed DE 10 2018 206 023 A1 in addition, the possibility of an adjustability of the connection of the second, overhead leaf springs on the vehicle body. This makes it possible to change the standing height of the motor vehicle or the prestressing of the leaf spring device.

The object of the invention is to expand the possible uses of such a motor vehicle wheel suspension.

To solve this problem, a motor vehicle wheel suspension according to patent claim 1 is proposed. This is characterized in particular by the fact that an externally powered drive device acts on the first fastening device, by means of which the first fastening device can be pivoted.

This enables a wheel-specific torque change, since an individual torque can be introduced into the respective leaf spring device. Compared to DE 10 2018 206 023 A1 the actuators are in a different place here. In addition to level control, this also allows roll stabilization and body control in the directions of lift, pitch and roll. This practically corresponds to a wheel-specific spring base adjustment.

Special embodiments of the invention are the subject of further patent claims. To facilitate the adjustment, the drive device can include a gear. On the one hand, this favors a more flexible arrangement of a motorized drive. In addition, a structurally small drive can be used through a suitable selection of the translation. The gearbox can be single-stage or multi-stage.

In one embodiment variant, the transmission includes a gear stage which, due to its compact design and its torque transmission potential, can be easily implemented under cramped spatial conditions.

Furthermore, a toothing can be provided on the first fastening device, which toothing engages with a toothing on a drive element. The teeth can be formed directly on a clamping element for clamping the first ends of the leaf spring device. However, it is also possible to attach a toothed component specifically to a clamping element. The drive element is driven by a motor, for example an electric motor or the like.

In one embodiment variant, the drive element is a gear wheel.

According to a further special embodiment of the invention, the first fastening devices on both wheel sides are driven independently of one another. This can be realized, for example, by providing a separate motor for each side of the wheel. This achieves maximum flexibility when introducing torque into the two leaf spring devices, so that there is a great deal of tuning potential available for body control, including roll stabilization.

With regard to accommodation in the vehicle, it is advantageous if the drive elements and the first fastening devices on both wheel sides are arranged together on a cross member of an auxiliary frame.

According to a further special embodiment of the invention, the drive devices on both wheel sides are controlled with an adjustment dynamic of 5 to 8 Hz, which means that dynamic driving conditions, for example in terms of roll stabilization or other dynamic body control, can be easily influenced.

According to a further special embodiment of the invention, the leaf spring device also has a second fastening device wheel-side support, which is arranged at a second end of the first leaf spring, and a third fastening device for vehicle body-side support, which is arranged at a second end of the second leaf spring.

The leaf spring device is preferably configured such that the main extension direction of the first leaf spring and the main extension direction of the second leaf spring enclose an acute angle, in particular an acute angle of 15° to 35°, when the spring device is in the relaxed state.

More preferably, the leaf spring device is configured such that the first and second leaf springs each extend in the vehicle transverse direction or enclose an angle of maximum +/-15° with the vehicle transverse direction when viewed in a horizontal plane.

• 1 ein Ausführungsbeispiel einer Kraftfahrzeug-Radaufhängung mit einer Blattfedereinrichtung je Radseite nach der Erfindung in Fahrzeuglängsrichtung gesehen, und in
• 2 eine weitere Ansicht der Kraftfahrzeug-Radaufhängung gemäß 1.

The invention is explained in more detail below using an exemplary embodiment illustrated in the drawing. The drawing shows in:

• 1 an embodiment of a motor vehicle wheel suspension with a leaf spring device per wheel side according to the invention seen in the vehicle longitudinal direction, and in
• 2 another view of the motor vehicle wheel suspension according to FIG 1 .

The embodiment in the 1 and 2 shows a motor vehicle wheel suspension 1 with a leaf spring device 10 per wheel side. A wheel carrier 20 is supported against a vehicle body 30 and an auxiliary frame 40 via the leaf spring device 10 .

The motor vehicle wheel suspension 1 is particularly suitable for rear axles of passenger cars and light commercial vehicles.

The leaf spring device 10 has a first leaf spring 11 and a second leaf spring 12 . Both leaf springs 11 and 12 are made from a fiber-reinforced plastic, for example glass-fiber-reinforced plastic (GRP) or carbon-fiber-reinforced plastic (CFRP). In particular, they can be designed in the form of rods or beams. The two leaf springs 11 and 12 can be designed as separate components, as shown. However, it is also possible to integrate both leaf springs 11 and 12 into a one-piece body made of fiber-reinforced plastic.

As 1 can also be removed, both leaf springs 11 and 12 can have a different length. The first leaf spring 11 preferably has a greater length than the second leaf spring 12.

The first and second leaf springs 11, 12 are preferably located in the in 1 Vertical plane shown one above the other, so that taking into account the intended installation position on a motor vehicle, the first leaf spring 11 can also be referred to as the leaf spring lying below and the second leaf spring 12 as the leaf spring lying on top.

Furthermore, the first leaf spring 11 and the second leaf spring 12 of each leaf spring device 10 are spatially arranged in a special manner, which will be explained in more detail below, in order to jointly form a resilient V-shaped structure. For this purpose, in each case a first end 11a of the first leaf spring 11 and a first end 12a of the second leaf spring 12 are brought together and connected to one another in order to form the tip of the V-shaped structure. The tips of the two leaf spring devices 10 point towards one another. The opposite second ends 11b and 12b of the first and second leaf springs 11, 12 respectively form the free ends of the V-shape. The tip of the V-shaped structure, i.e. the first ends 11a and 12a, and the free, second ends 11b, 12b each serve as force application points in the respective leaf spring device 10.

To achieve the lowest possible installation heights, the V-shape can be designed such that the main extension direction of the first leaf spring 11 and the main extension direction of the second leaf spring 12 enclose an acute angle α when the leaf spring device 10 is in the relaxed state. This acute angle α is preferably in the range of 15° to 35°, so that on the one hand a low installation height can be ensured and on the other hand a sufficient deflection potential for energy absorption is available. 1 shows the spring device 10 in a somewhat compressed state, which corresponds to the installation position in the vehicle.

A corresponding fastening device is provided at each of the aforementioned force application points.

A first fastening device 13 is arranged on the first and second leaf springs 11 and 12 in the region of the first ends 11a and 12a that have been brought together. This first fastening device 13 is used in the motor vehicle wheel suspension 1 for support on the vehicle body approximately in the middle of the vehicle. The leaf spring device 10 is in the area of the tips of the V-shaped structure on the vehicle body 30 or on a vehicle body Structure such as a subframe 40 or the like is supported.

Furthermore, a second fastening device 14 is arranged on the free, second end 11b of the first leaf spring 11 in the exemplary embodiment shown. The second fastening device 14 is used for wheel-side support, for example on the wheel carrier 20 or some other wheel guide element.

Furthermore, a third fastening device 15 can be provided on the free, second end 12b of the second leaf spring 12 for support on the vehicle body near the wheel.

Due to the shorter length of the second leaf spring 12, as in 1 shown by way of example, whose vehicle body-side support point on the second end section 12b of the second leaf spring 12 is closer to the center of the vehicle when the spring device 10 is arranged in the vehicle transverse direction than the wheel-side support point of the first leaf spring 11.

At the in 1 In the exemplary embodiment shown, the first fastening device 13 has a clamping element 13a for bracing the first ends 11a and 12a of the first and second leaf springs 11, 12 against one another. By means of the clamping element 13a, a rotational movement of the first leaf spring 11, which results from a spring deflection and/or a deformation thereof, can be transmitted to the second leaf spring 12 and vice versa.

The clamping element 13a can be designed, for example, as a fork-shaped claw into which the first ends 11a and 12a of the first and second leaf springs 11, 12 are inserted. However, the configuration of the clamping member 13a is not limited to the shape of such a claw. Rather, other configurations are also possible. Tensioning can take place, for example, by means of tensioning bolts 13b, which perpendicularly penetrate the leaf springs 11, 12 in the region of the clamping element 13a. A uniform distribution of the clamping force over the surface of the ends 11a and 12a can be achieved via corresponding flange sections 13c of the claw.

The leaf spring device 10 is mounted pivotably about a defined axis of rotation A on the vehicle body side via the first fastening device 13 . For this purpose, the first fastening device 13 can have, without being restricted to this embodiment variant, a receptacle 13d for a bearing for pivotable support on the vehicle body or an auxiliary frame provided on the vehicle body. In the exemplary embodiment shown, a bearing eye is integrated into the first fastening device 13 by way of example. However, a bearing bolt or the like can also be used as a receptacle 13d for a bearing, by means of which a pivotable bearing can be implemented.

The second fastening device 14 can have, for example, a bearing mount 14a for pivotable support on a wheel carrier. 1 shows a bearing receptacle 14a designed as a fork, purely by way of example, via which, for example, a rubber bearing can be accommodated. As already explained in the context of the first fastening device 13, however, other structures such as a bearing pin or the like are also fundamentally possible as the bearing receptacle 14a.

In principle, it is possible to fasten the second end 12b of the second leaf spring 12 directly to a structure on the body. In the simplest case, the third fastening device 15 then consists only of one or more fastening means such as clamping bolts and the like. However, an articulated coupling, for example, can also be provided at this point in order to introduce an additional degree of freedom.

In addition, it is possible to use the third fastening device 15 to compensate for movements relative to the vehicle body 30 or the structure fixed to the vehicle body, which can hardly be avoided as a result of the deformation of the second leaf spring 12 . At the in 1 illustrated embodiment, the third fastening device 15 also has a coupling element 15a for connecting the free end of the second leaf spring 12 from below to a section of the vehicle body. For its more detailed design and for the body-side connection of the second leaf spring 12 is on DE 10 2016 220 325 A1 , DE 10 2018 206 023 A1 , DE 10 2018 215 111 B3 and DE 10 2019 203 366 A1 referred.

According to the invention, for each leaf spring device 10 an actuator acts on the first fastening device 13, ie a drive device 16 operated by external energy, by means of which the respective first fastening device 13 can be pivoted. In 1 the relevant axis of rotation for pivoting the first leaf spring device 13 is marked with A. This axis of rotation A extends essentially parallel to a longitudinal direction x of the vehicle.

An individual moment about the axis of rotation A can be introduced into each of the two leaf spring devices 10 by means of the respective drive device 16 . This leads due to the clamping of the respective leaf spring device 10 to a corresponding bracing of the same.

An adjustment of the wheel-specific spring forces can thus be effected on the two first fastening devices 13 .

As a result, on the one hand, a quasi-static level adjustment is possible.

In addition, the body modes can be dynamically controlled in lifting, pitching and rolling.

If necessary, the type of actuation on a rear axle can be combined with a corresponding technology on a front axle in order to achieve further refinement of body control.

For this purpose, the drive devices 16 on both wheel sides or leaf spring devices 10 can be controlled with a high adjustment dynamics of preferably 5 to 8 Hz in order to implement a wheel-specific introduction of force.

In the exemplary embodiment shown, the drive device 16 has a gear with one gear stage. However, the transmission can also be multi-stage.

Preferably, at least one, optionally the only, gear stage is a gear stage.

1 shows an example of a toothing 16a provided on the first fastening device 13, which is in engagement with a toothing 16b on a drive element 16c of the drive device 16.

The toothing 16a on the first fastening device 13 can be designed, for example, as a gearwheel or gearwheel segment, which is fastened to the clamping element 13a. It is also possible to form teeth 16a directly on the clamping element 13a.

The drive element 16c can also be in the form of a gear wheel which is connected in a torque-proof manner to an output shaft of a motor 16d and is therefore driven by this motor 16d. A very compact motor 16d, in particular an electric motor, can be used by selecting an appropriate transmission.

Instead of a gear drive, a belt drive, in particular a toothed belt drive, is also possible.

In the illustrated embodiment in 1 the first fastening devices 13 of both wheel sides are driven independently of one another. For this purpose, each leaf spring device 10 has its own motor 16d and its own gear.

As a modification of this, a single motor can also be drivingly coupled to both fastening devices 13 . If a reversing stage is provided for one side of the wheel, at least one synchronous pivoting of the first fastening devices 13 in opposite directions about their respective axes of rotation A can thereby be achieved in order to bring about level regulation.

The drive elements 16c and the first fastening devices 13 of both wheel sides are preferably arranged together on a cross member 41 of the auxiliary frame 40 on the body side, but can also be fixed in another way on the vehicle body side. The motors 16d on both wheel sides or leaf spring devices 10 can also be fixed to the subframe 40.

Out of 2 the further structure of an exemplary rear axle 1 can be seen, which has a leaf spring device 10 of the type explained above on each wheel side.

The already mentioned wheel carrier 20 is supported in addition to the leaf spring device 10 via further wheel guide members against the vehicle body 30 or a structure fixed to the vehicle body such as the auxiliary frame 40 .

In the present case, the other wheel control elements comprise a trailing arm 22 on each wheel side, as well as an upper transverse link 23 and a lower transverse link 24.

Furthermore, a vibration damper 25 can be seen, which is supported with one end on the wheel carrier 20, optionally also on a wheel guide member, and with its other end on the vehicle body 30.

The motor vehicle wheel suspension 1 also has a stabilizer 26 which reduces mutual deflection of the wheel carrier 20 and thus the vehicle wheels.

The present motor vehicle wheel suspension 1 manages without a helical spring to support the vehicle mass. In the present case, their function is taken over by the leaf spring devices 10 . However, it is possible to additionally use conventional coil springs to support the vehicle mass in a motor vehicle wheel suspension 1 which contains leaf spring devices 10 of the type explained above.

The illustrated motor vehicle wheel suspension 1 is only of an exemplary nature in order to explain the installation position of the leaf spring devices 10 in such a detail. It must therefore be expressly emphasized that corresponding leaf spring devices 10 can also be used in motor vehicle wheel suspensions 1 other than those shown, in order to support the mass of the vehicle body against the vehicle wheels and, if necessary, also take over wheel control tasks.

The leaf spring devices 10 explained above are installed in the motor vehicle wheel suspension 1 in such a way that the first and second leaf springs 11 and 12 each extend in the vehicle transverse direction y or at an angle of maximum +/-15 with the vehicle transverse direction y when viewed in a horizontal plane xy ° include.

Furthermore, the leaf spring devices 10 each extend very far in the direction of the center of the vehicle, resulting in a great length for the first and second leaf springs 11 and 12 with a correspondingly high energy absorption capacity. Due to the selected V-shape, the overall height in the vertical direction z of the vehicle remains low.

When the motor vehicle is in the resting position on a horizontal surface, the first leaf springs 11 run predominantly horizontally, i.e. they enclose an angle of maximum +/-10° with a horizontal plane xy.

In order to achieve the greatest possible length of spring device 10 in vehicle transverse direction y, first fastening devices 13 can be arranged in vehicle transverse direction y, preferably in a middle third, and more preferably in a middle fifth, around the longitudinal center axis of the vehicle in relation to the track width of the vehicle. The connection to the auxiliary frame 30 takes place here, for example, via a rubber bearing in the receptacle 13d of the first fastening device 13, so that the leaf spring device 10 can pivot about the axis of rotation A running in the longitudinal direction x of the vehicle.

The first fastening devices 13 are preferably arranged in a central area in the vehicle transverse direction y, which is delimited in the vehicle transverse direction y by the longitudinal beams 31 of the vehicle body 30 .

This results in a flat motor vehicle axle, which enables a low trunk or loading space edge and a high trunk or loading space width.

The weight advantage of the leaf springs 11 and 12 made of fiber-reinforced plastic can be converted practically completely into a weight reduction of the vehicle weight, since no weight-increasing stiffening measures are necessary in the area of the body-side connection of the leaf spring devices 10 .

By actuating the leaf spring devices 10 on the first fastening devices 13 in a partially supporting system, it is possible to resolve the conflict between driving dynamics and driving comfort that usually occurs in chassis design within the framework of a special rear axle concept with leaf springs 11, 12 arranged in an X-shape. A partially supporting system has proven to be particularly advantageous for an electrically actuated vehicle axle. The partially supporting system is characterized in that the basic load of the motor vehicle is borne by the spring connected in parallel with the drive device 16 and only the additional active forces are applied by the drive device 16 . This advantageously results in the drive device 16 being able to be dimensioned smaller in comparison to a fully supporting system, since the full load does not have to be borne permanently by the drive device 16 .

The invention was explained in more detail above using an exemplary embodiment and further modifications. The embodiment and the modifications serve to prove the operability of the invention. Individual technical features that have been explained above in the context of other individual features can also be implemented independently of these and in combination with other individual features, even if this is not expressly described, as long as this is technically possible. The invention is therefore expressly not limited to the exemplary embodiments specifically described, but rather includes all configurations defined by the patent claims.

Reference List

1

automotive wheel suspension

10

leaf spring device

11

first leaf spring, below

12

second leaf spring, overhead

11a

first end of the first leaf spring 11

11b

second end of the first leaf spring 11

12a

first end of the second leaf spring 12

12b

second end of the second leaf spring 11

13

first fastener

13a

clamping

13b

clamping bolt

13c

flange section

13d

Mount for bearing (bearing mount)

14

second fastener

14a

Mount for bearing (bearing mount)

15

third fastener

15a

coupling element

16

drive device

16a

gearing

16b

gearing

16c

drive element

16d

engine

20

wheel carrier

22

trailing arm

23

upper wishbone

24

lower wishbone

25

vibration damper

26

stabilizer

30

vehicle body

31

side members

40

subframe

41

crossbeam

A

axis of rotation

x

vehicle longitudinal direction

y

vehicle transverse direction

e.g

vehicle elevation

a

angle

Claims (10)

Motor vehicle wheel suspension (1) with a leaf spring device (10) on each wheel side, each leaf spring device (10) comprising: a first leaf spring (11) made of fibre-reinforced plastic, a second leaf spring (12) made of fibre-reinforced plastic, the first leaf spring (11) and the second leaf spring (12) are brought together at a respective first end (11a, 12a) to form a V-shaped structure, and a first fastening device (13) for pivotable vehicle body-side support, which the brought together first ends (11a, 12a ) of the first and second leaf springs (11, 12), characterized in that an externally powered drive device (16) acts on the first fastening device (13), by means of which the first fastening device (13) can be pivoted. Motor vehicle wheel suspension (1) after claim 1 , characterized in that the drive device (16) comprises a gear stage. Motor vehicle wheel suspension (1) after claim 2 , characterized in that the gear stage is a gear stage. Motor vehicle wheel suspension (1) after claim 3 , characterized in that a toothing (16a) is provided on the first fastening device (13) and engages with a toothing (16b) on a drive element (16c), and that the drive element (16c) is driven by a motor (16d) is driven. Motor vehicle wheel suspension (1) after claim 4 , characterized in that the drive element (16c) is a gear. Motor vehicle wheel suspension (1) after claim 4 or 5 , characterized in that the drive elements (16c) and the first fastening devices (13) of both wheel sides are arranged together on a cross member (41) of an auxiliary frame (40). Motor vehicle wheel suspension (1) according to one of Claims 1 until 6 , characterized in that the first fastening devices (13) of both wheel sides are driven independently of one another by a respective drive device (16). Motor vehicle wheel suspension (1) according to one of Claims 1 until 7 , characterized in that the drive devices (16) on both wheel sides are controlled with an adjustment dynamic of 5 to 8 Hz. Motor vehicle wheel suspension (1) according to one of Claims 1 until 8th , characterized in that the leaf spring device (10) has a second fastening device (14) for wheel-side support, which is arranged at a second end (11b) of the first leaf spring (11), and a third fastening device (15) for vehicle body-side support, which is arranged at a second end (12b) of the second leaf spring (12). Motor vehicle wheel suspension according to one of Claims 1 until 9 , characterized in that the main extension direction of the first leaf spring (11) and the main extension direction of the second leaf spring (12) in the relaxed state of the spring device (10) enclose an acute angle (α), in particular an acute angle of 15° to 35°, and/or that the first and second leaf springs (11, 12) each extend in the transverse direction of the vehicle or with the transverse direction of the vehicle when viewed in one enclose an angle of maximum +/-15° with the horizontal plane.

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