DE102012001671A1 - Rear axle for motor car, has legs that are provided in regions between end portions of trailing arm - Google Patents

Abstract

The rear axle has two trailing arms that is provided end portions connected with a cross element or sub-frame of car respectively. The trailing arm has two legs that are extended one above the other, and are made of fiber reinforced plastic. The legs are provided in the regions between the end portions of the trailing arm. A clamping piece is provided between the legs and is abut against the cross beam.

Description

The invention relates to a motor vehicle rear axle, comprising two trailing arms, each having a first and second Erdabschnitt, and a cross member, wherein the trailing arms are each coupled with its first end portion to a vehicle body or subframe and are connected at its second end portion to the cross member.

In vehicle construction, semi-rigid rear axles are mainly composite beam axles and torsion crank axles.

In the case of beam steering axles, such as for example DE 195 42 522 A1 and DE 198 40 134 A1 are known, the cross member connecting the trailing arm in the front half of the axis in the direction of travel. The trailing arms are designed here as torsion and bending resistant components. A mutual compression and rebound of the vehicle wheels is made possible by the torsional capability of the cross member. A lateral force support takes place solely on the trailing arm.

In Torsionskurbelachsen the trailing arm are bending stiff only around the vehicle transverse direction, so that an additional lateral force support, for example in the form of a Panhardstabs is required. This requires additional space. At one off DE 10 2006 018 641 A1 known rear axle of Panhardstab is arranged behind the cross member, which in turn is located near the wheel axle. At one off EP 0 458 665 B1 known rear axle of Panhardstab attacks on a trailing arm and extends diagonally through the space between the trailing arms.

A particularly inexpensive and lightweight rear axle with good comfort and good driving dynamics is off DE 10 2008062 901 A1 known. In this, the cross member connects the trailing arm in the wheel carriers together. In addition, the trailing arm on an open, rigid, but torsionally soft profile cross-section. The required in Torsionskurbelachsen additional strut, which limits the scope for surrounding components such as a fuel tank or the exhaust system is not required because the lateral forces are supported solely on the trailing arm. This allows a short vehicle undercarriage, in which the cross member between a fuel tank and a silencer of the exhaust system is arranged. This allows a fuel tank to extend into the space between the trailing arms.

Especially in motor vehicles with alternative drives large-volume energy storage such as batteries or gas containers must be accommodated crash-proof as possible on the vehicle. For this purpose, in particular the space under the rear seats to the rear wheel axle is preferred. Since such energy stores usually have a very high weight, the center of gravity of the vehicle shifts to the rear.

The invention is based on the object to remedy this situation. In particular, the invention aims to provide a lightweight motor vehicle rear axle, which allows sufficient space for the crash-proof housing large-volume energy storage.

This object is achieved by a motor vehicle rear axle according to claim 1. The motor vehicle rear axle according to the invention comprises two trailing arms, each having a first and a second end portion, and a cross member, wherein the trailing arms are each coupled with its first end portion to a vehicle body or subframe and are connected at its second end portion to the cross member. It is characterized in that the trailing arms each have two superimposed legs made of fiber-reinforced plastic, which are spaced apart in the region between the first and second end portion.

In the present case, "fiber-reinforced plastic" is understood to mean all fiber-plastic composite materials (FRP). For example only Carbanfaserverstärkter plastic (CFRP) and glass fiber reinforced plastic (GRP) may be mentioned here.

Due to the particularly lightweight design of the rear axle of a displacement of the vehicle center of gravity is counteracted to the rear. This has a positive effect on the driving behavior.

The connection of the cross member on in relation to the forward direction of travel rear end portion of the trailing arm allows the accommodation of a large-volume energy storage, such as an electric battery, which may extend into the area between the trailing arms to the cross member.

By a targeted vote of the height distance between the two legs of a trailing arm and the shape of the same, the reciprocal spring rate of the respective trailing arm made of fiber-reinforced plastic can be tailored.

Overall, this provides a new rear axle type is created, which is particularly suitable for motor vehicles with electric drive and gas-powered vehicles, but in principle also in Vehicles with conventional drive can be used.

Advantageous embodiments of the invention are specified in further claims.

The two legs of a trailing arm may be provided as separate components, which are each mounted on the body side and on the cross member. According to an advantageous embodiment, the trailing arms form at the second end portion in each case an arc portion which engages around the cross member and merges at its two ends in each case one of the legs. This results in an integral component, in one piece. manufactured and assembled as such. In addition to a simplification of the assembly, such a configuration also allows greater stability and thus possibly a slimmer and more space-saving design.

The legs made of fiber-reinforced plastic preferably have a fiber path extending in the longitudinal direction thereof, which continuation follows the curved section of the arch form. As a result, the component strength is further improved.

According to a further advantageous embodiment of the invention, the legs are brought together at the first end portion of the trailing arm. As a result, they can be easily mounted together on the vehicle body. Preferably, the legs are not only against each other, but are also connected to the first end portion of the trailing arm cohesively to further increase the stability of the double spring thus formed.

To facilitate attachment to the vehicle body or to a subframe, one or more metal mounting sockets may be further laminated to the fiber reinforced plastic of the trailing arm at the first end portion. The trailing arm can be attached to the vehicle with high biasing force, without the plastic material of the trailing arm is damaged.

The trailing arm can be fixed for example by gluing to the cross member. However, other joining techniques are possible in principle. According to an advantageous embodiment of the invention, the cross member in the region of the connection of the trailing arm on a non-circular profile cross-section. As a result, a particularly torsionally stiff connection of the trailing arm is achieved to the cross member. In addition to such a positive connection, said components can also be glued together.

Furthermore, a clamping piece between the legs may be used per trailing arm. This clamping piece is arranged in the region of the cross member and is preferably against the cross member. As a result, the stable connection of the trailing arm is further improved on the cross member.

For weight reduction, the cross member may be made of a material whose specific mass is less than that of steel. For example, the cross member may be made of fiber-plastic composite or light metal, whereby the weight of the axle is further reduced.

According to a further advantageous embodiment of the invention, two wheel carrier made of plastic with injected metal journal are attached to end portions of the cross member for further weight reduction.

On the axis described above, a strut with a vibration damper and a bodybuilder can be provided per vehicle. Furthermore, it is possible to spatially separate vibration absorbers and mounting springs. According to an advantageous embodiment, the rear axle but comes without additional springs for support against the vehicle body, so that each vehicle only a vibration damper acts on the rear axle. The function of body-side springs is taken over in this case by the trailing arms.

The invention will be explained in more detail with reference to an embodiment shown in the drawing. The drawing shows in:

1 a schematic representation of a motor vehicle with a rear axle according to an embodiment of the invention and with a large-volume energy storage;

2 a spatial view of the rear axle with regard to their connection to the rear of a motor vehicle;

3 a spatial view of the rear axle in construction position;

4 a spatial view of the rear axle when cornering with mutual compression;

5 a detailed view of the connection of a trailing arm to the cross member,

6 a side view of a trailing arm, and in

7 a detailed view of the coupling of a trailing arm on the vehicle body.

1 shows a schematic representation of a passenger vehicle 1 in which a large-volume energy storage 2 is arranged in the area in front of the rear wheel axle A. The energy storage 2 is for example an electric battery or a pressure vessel for gas. In principle, the energy storage 2 but also be a conventional fuel tank.

To provide a large accommodation space for the energy storage 2 is a space-saving rear axle 10 provided with a structurally simple structure, which counteracts due to their low total weight of a shift of the vehicle's center of gravity to the rear, that is opposite to the forward direction.

The in the 2 to 4 illustrated rear axle 10 has two trailing links 11 and a cross member connecting them 12 on. Each of the trailing arm 10 is with a first end section 13 to a vehicle body 3 , optionally also on an auxiliary frame thereof, coupled, and with a second end portion 14 torsionally rigid with the cross member 12 connected. This configuration is reminiscent of a torsion crank axle in terms of the arrangement of trailing links and cross beams. However, the rear axle according to the invention differs 10 fundamentally of such.

According to the invention, each of the trailing arm 11 two superimposed legs 14 and 15 on. Both thighs 15 and 16 extend predominantly in the vehicle longitudinal direction. They are at least in the region between the first and second end portion 13 and 14 spaced apart in the vehicle vertical direction. This is per trailing arm 10 a double spring formed. About the distance between the two thighs 15 and 16 as well as the shape of the legs 15 and 16 can spring rate the rear axle 10 be tuned during simultaneous and mutual compression.

3 shows the two trailing arms 11 the rear axle 10 in construction position. When cornering, there is a mutual compression of the vehicle wheels. The outside of the curve wheel springs in, while the inside of the curve rebounds. Such reciprocal compression is in 4 shown. As you can see from the illustration, this results in an elastic bending deformation of the trailing arm 11 and their thighs 15 and 16 around a bending axis running in the vehicle transverse direction. The crossbeam 12 In contrast, has a much greater torsional and bending stiffness and can therefore be referred to as torsion and bending stiff. The lateral force support takes place via the trailing arm 11 , which are firmly clamped on the body side and in turn are rigid in the vehicle transverse direction.

In the illustrated embodiment, both legs 15 and 16 a longitudinal member 10 each formed strip-shaped. Preferably, the legs 15 and 16 each an approximately rectangular cross-sectional profile. In the area of the connection to the crossbeam 12 may be made a broadening of the cross section. However, deviating shapes are also possible as long as two roughly mutually parallel, spaced apart in the vertical direction spring elements are formed, which are flexurally rigid in the vehicle transverse direction and flexible about an axis in the vehicle transverse direction.

The thigh 15 and 16 as preferably the entire trailing arms 11 consist of a fiber-reinforced plastic, such as CFRP or GRP, which can be realized with high strength, a slim design and low weight.

Like that 2 to 6 can be further removed, in the illustrated embodiment, the two legs 15 and 16 a trailing arm 11 through a bow section 17 which the cross member 12 encompasses, integrally connected. The bow section 17 goes at both ends directly into each one of the two legs 15 and 16 over, so that the shape of a lying "U" s results. The fiber flow F in the side member 11 follows the longitudinal direction of the legs 15 and 16 and sits down along the arch section 17 continued. In the area of the bow section 17 Thus follows the fiber profile of the arch form (see. 6 ). Due to the continuous fiber flow F is a particularly high component strength and load capacity of the trailing arm 11 achieved.

For stable, torsionally stiff connection of the trailing arm 11 to the cross member 12 the latter has a non-circular profile cross-section in the connection region, resulting in the snuggled arc section 17 of the longitudinal member 11 a positive connection results. In the illustrated embodiment, the cross member 12 a square profile with rounded corners, on the outer shape of the arc section 17 is adjusted. Instead of a square profile, however, other profile shapes, in particular polygonal profiles, can be provided.

Furthermore, each trailing arm 11 a clamping piece 18 between its legs 15 and 16 used. This clamp 18 is the outer contour of the cross member 12 adapted and reinforced the positive connection of trailing arm connection. By that clamping piece 18 becomes the attachment area of the trailing arm 11 from the resilient portion between the end portions 13 and 14 largely decoupled, creating a particularly stable and durable connection of the trailing arm 11 on the cross member 12 is ensured.

Incidentally, the cross member 12 tubular, wherein in the region between the attachment points of the trailing arm 11 preferably a circular cross-section is provided. To reduce the total weight of the rear axle 10 consists of the cross member 12 made of a fiber-reinforced plastic, such as CFRP or GRP. In a preferred embodiment, the fibers of the fiber-reinforced plastic close with longitudinal generatrices of the cross member 12 a winding angle α in the range of 5 to 40 °. However, it is also possible, the cross member 12 made of light metal.

The two thighs 15 and 16 of each trailing arm 11 are further at the first end portion 13 of the trailing arm merged. Basically, it is possible, unconnected, free leg ends together with the vehicle body 3 to tense. In the illustrated embodiment, however, as in 7 shown the ends of the thighs 15 and 16 cohesively connected to each other, so that the trailing arm 11 , as in 6 represented, forms a closed loop of fiber-reinforced plastic. The trailing arm 11 thus represents an easy-to-handle one-piece component during assembly.

For fastening the trailing arm 11 on the vehicle body 3 are at the first end portion 13 one or more mounting sockets each 20 made of metal laminated into the fiber-reinforced plastic. In the illustrated embodiment, for the purpose of a particularly stable clamping of the first end portion 13 two mounting sockets 20 intended. Through the mounting sockets 20 Clamping bolts extend 21 , which are bolted to the vehicle body. The metallic mounting sockets 20 Make sure that the plastic material of the trailing arm 11 when bracing against vehicle body 3 not damaged. For this purpose, each further serves a bearing block 22 per trailing arm 11 , in turn, with the vehicle body, in 2 by way of example with a side member 4 of the vehicle body 3 , screwed or otherwise attached to this. The bearing block 22 overlaps the first end section 13 of the trailing arm 11 with a tab 23 which flat at the first end portion 13 is applied. Because of the tab 23 Heads are based 24 the clamping bolt 21 or by reversing the nuts on the tab 23 and not directly on the trailing arm 11 from.

At the side over the trailing arm 11 protruding ends of the cross member 12 are two wheel carriers 19 intended. To further reduce weight and the wheel are 19 made of plastic and attached to the cross member in the illustrated embodiment. However, it is also possible the wheel carrier 19 and the cross member 12 to manufacture as a one-piece integral component. Furthermore, it is possible the wheel carrier 19 not on the crossbeam 12 but at the trailing arms 11 to fix. To accommodate a wheel bearing is on the wheel 19 a journal 25 intended. This is preferably made of metal and in the plastic material of the wheel carrier 19 embedded. In particular, the wheel carrier 19 be manufactured as injection molded parts.

As already explained, the trailing arm 11 assume the function of conventional body springs, ie the rear axle 10 as well as the vehicle wheels 5 opposite the vehicle body 3 support elastically in vehicle vertical direction. Further attacks per vehicle 5 a vibration damper 26 at the rear axle 10 at. The vibration damper 26 is inclined with its upper end in the forward direction and employed to the vehicle vertical direction at an angle in the range of 5 ° to 30 °. Furthermore, the upper end may additionally be inclined in the direction of the vehicle longitudinal center axis, suitable angles being in the range of 0 ° to 15 °. On the wheel side, the vibration damper is in the forward drive direction and in the vehicle vertical direction below the wheel center on the wheel carrier 19 coupled. As 2 can be removed, lies the lower end of the vibration 26 over the rear second end portion 14 of the trailing arm 11 , The space between the trailing arms 11 is thus due to the vibration damper 26 not or only slightly affected. This space allows the accommodation of a large-volume energy storage 2 ,

For this it is also advantageous that the cross member 12 viewed in the vehicle longitudinal direction in the area of the rear wheel axle A drunk. In the illustrated embodiment, the profile of the central region of the cross member lies 12 between the trailing arms 11 below and predominantly behind the wheel axle A. It is even possible to shift this central area entirely behind the wheel axle A.

In a modification of the illustrated embodiment, the vibration damper 26 also be executed as a strut. Furthermore, it is basically possible, in addition to the resilient trailing arms 11 between the rear axle 10 and the vehicle body 3 to integrate additional construction springs.

In all cases, results in a lightweight rear axle motor vehicle, which allows a large space for the crash-proof housing large-volume energy storage, such as batteries, gas pressure vessels or other fuel tanks.

By a targeted vote of the height distance between the two legs of a trailing arm and the shape of the same, the equilateral and reciprocal spring rate of the respective trailing arm made of fiber-reinforced plastic can be adjusted specifically.

LIST OF REFERENCE NUMBERS

1

Passenger car

2

energy storage

3

vehicle body

4

longitudinal beams

5

wheel

10

rear axle

11

Trailing arm

12

crossbeam

13

first end section

14

second end section

15

leg

16

leg

17

arc section

18

clamp

19

wheel carrier

20

mounting bushing

21

clamping bolt

22

bearing block

23

flap

24

head

25

journal

26

vibration

A

wheel axle

F

grain

α

winding angle

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 19542522 A1 [0003]
• DE 19840134 A1 [0003]
• DE 102006018641 A1 [0004]
• EP 0458665 B1 [0004]
• DE 102008062901 A1 [0005]

Claims (10)

Rear vehicle axle, comprising: two trailing links ( 11 ) each having a first and a second end portion ( 13 . 14 ), and a cross member ( 12 ), the trailing arms ( 11 ) each with its first end portion ( 13 ) can be coupled to a vehicle body or subframe and at its second end portion ( 14 ) with the cross member ( 12 ), characterized in that the trailing arms ( 11 ) each two superimposed legs ( 15 . 16 ) made of fiber-reinforced plastic, which in the region between the first and second end portion ( 13 . 14 ) are spaced from each other. Motor vehicle rear axle according to claim 1, characterized in that the trailing arm ( 11 ) at the second end portion ( 14 ) each have an arc section ( 17 ) forming the crossbeam ( 12 ) and at its two ends in each of the legs ( 15 . 16 ) passes over. Motor vehicle rear axle according to claim 2, characterized in that the legs ( 15 . 16 ) of fiber-reinforced plastic have a longitudinally extending fiber profile (F) extending at the arc portion ( 17 ) continues following the bow shape. Motor vehicle rear axle according to one of claims 1 to 3, characterized in that the legs ( 15 . 16 ) at the first end portion ( 13 ) of the trailing arm ( 11 ) are brought together. Motor vehicle rear axle according to one of claims 1 to 4, characterized in that the legs ( 15 . 16 ) at the first end portion ( 13 ) of the trailing arm ( 11 ) are cohesively connected to each other. Motor vehicle rear axle according to one of claims 1 to 53, characterized in that at the first end portion ( 13 ) one or more mounting sockets ( 20 ) are laminated from metal into the fiber reinforced plastic. Motor vehicle rear axle according to one of claims 1 to 3, characterized in that each trailing arm ( 11 ) a clamping piece ( 18 ) between its legs ( 15 . 16 ) is inserted and against the cross member ( 12 ) is present. Motor vehicle rear axle according to one of claims 1 to 8, characterized in that the cross member ( 12 ) in the region of the connection of the trailing arm ( 11 ) has a non-circular profile cross-section. Motor vehicle rear axle according to one of claims 1 to 8, characterized in that two wheel carrier ( 19 ) made of plastic with an injected journal ( 25 ) of metal at end portions of the cross member ( 12 ) are attached. Motor vehicle rear axle according to one of claims 1 to 9, characterized in that per vehicle wheel ( 5 ) a vibration damper ( 26 ) on the rear axle ( 10 ) and the rear axle ( 10 ) without additional springs for support against the vehicle body ( 3 ).

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