GB2555452A

GB2555452A - Motor vehicle and control arm therefore

Info

Publication number: GB2555452A
Application number: GB1618254.5A
Authority: GB
Inventors: V Mazur Dmitriy; Mazur Oleg; L Geisier Robert
Original assignee: GM Global Technology Operations LLC
Current assignee: GM Global Technology Operations LLC
Priority date: 2016-10-27
Filing date: 2016-10-27
Publication date: 2018-05-02
Also published as: GB201618254D0

Abstract

A control arm 2 for use on a motor vehicle suspension system is provided. The control arm 2 comprises front and rear joints 3, 4 for pivotably connecting to a vehicle frame 1, a third joint 7 for connecting to a wheel 20, a web 8 extending between the rear and third joints 4, 7 and a branch 9 which extends frorn a branching portion 10 of the web 8 to the front joint 3. A breaking point 21 is formed by locally weakening the branch 9. A vehicle including such a control arm is also disclosed.

Description

(71) Applicant(s):

GM Global Technology Operations LLC (Incorporated in USA - Delaware)

PO Box 300, 300 Renaissance Center, Detroit, 48265-3000, United States of America (56) Documents Cited:

EP 3069906 A1 DE 102012016851 A1 (58) Field of Search:

INT CL B60G Other: WPI: EPODOC

DE 102015212766 A1 US 20160236716 A1 (72) Inventor(s):

Dmitriy V. Mazur Oleg Mazur Robert L Geisier (74) Agent and/or Address for Service:

LKGLOBAL

Lorenz & Kopf PartG MbB Patentanwalte, Brienner Strasse 11, 80333 Munich, Germany (54) Title of the Invention: Motor vehicle and control arm therefore

Abstract Title: A control arm for a motor vehicle suspension system (57) A control arm 2 for use on a motor vehicle suspension system is provided. The control arm 2 comprises front and rear joints 3, 4 for pivotably connecting to a vehicle frame 1, a third joint 7 for connecting to a wheel 20, a web 8 extending between the rear and third joints 4, 7 and a branch 9 which extends from a branching portion 10 of the web 8 to the front joint 3. A breaking point 21 is formed by locally weakening the branch 9. A vehicle including such a control arm is also disclosed.

Fig. 3

This print takes account of replacement documents submitted after the date of filing to enable the application to comply with the formal requirements of the Patents Rules 2007.

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Fig. 3

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Motor vehicle and control arm therefore

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• · io Description

The present invention relates to a control arm for wheel suspension in a motor vehicle, and to a motor vehicle comprising such a control arm.

In order to ensure a maximum level of occupant safety, a motor vehicle should be designed such that in case of a front crash, the vehicle front portion can yield and absorb impact energy, while deformation of the occupant compartment is kept at a minimum. This requirement is particularly hard to fulfill in a shallow offset crash, i.e. a crash in which only a lateral region of the vehicle front portion comes in contact with an obstacle. Since in such a case, impact energy can only be absorbed by a small part of the vehicle front portion, low impact speeds can be sufficient to cause serious deformations which affect the occupant compartment. Unfortunately, the capacity to absorb impact energy is rather low in the lateral region of the vehicle front portion, in a particular in a compact car, since a large part of this lateral region is occupied by wheels. The rims of the vehicle wheels have to be rigid, so that they hardly absorb energy due to lack of deformation. The tyres, on the other hand, may yield, but hardly absorb energy in the process of doing so.

It is therefore an object of the present invention to improve occupant safety in case of a shallow overlap collision.

This object is achieved according to an embodiment of the present invention by a control arm for use in a vehicle wheel suspension system, the control arm comprising front and rear joints for pivotably connecting to a vehicle frame, a third joint for connecting to a wheel, a web extending between said rear and third joints and a branch which extends from a branching portion of said web to said front joint, wherein a breaking point is formed by locally weakening said branch. In this way, the branch can break under the force of an impact, so that a wheel attached to the wheel joint can move out of its wheel well. By doing so, the wheel does not contribute to the dissipation of collision energy, and the amount of energy which is consumed by breaking the branch is likely to be negligible. However, by the wheel moving out of the wheel well, the wheel well is deprived of support, and a large amount of energy is dissipated by crushing the wheel well and adjacent vehicle body elements which the wheel would otherwise protect from deformation.

In a branch having front and rear sidewalls, in order to subject the breaking point to high tensile stress in case of a collision, it is best located in the front sidewall.

If the front sidewall of the branch extends in a straight line with a front sidewall of the web, tensile stress cannot be relieved by straightening the front sidewalls, so that the breaking point is subjected to this stress substantially withut dampening.

The branch may be conveniently formed with a U-shaped cross section, the sidewalls forming the two sides of the U-shape.

The cutout might be a hotch, extending into the front sidewall from an edge thereof. Preferably, for reasons of stability under normal operating conditions, the cutout is a hole, distant from any edge of the front sidewall.

If the cutout is elongate, the direction of growth of that crack can to some extent be controlled by an appropriate orientation of the cutout. Preferably the cutout is upwardly inclined towards the front joint, so that if the crack grows in the same direction, it will extend across the branch, but not break the web, so that the rear and wheel joints stay connected.

The cutout is preferably pointed at its upper end, so as to facilitate crack growth in an upward direction, but not in a downward one. In this way, a substantial impact force is required in order to break the sidewall below the cutout, ensuring stability of the control arm under normal operating conditions, while in case of a crash, once the sidewall portion below the cutout has broken, the crack by which the branch will finally break will spread quite easily in the upward direction from the cutout.

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By having the cutout point away from the web, the crack can be prevented from spreading into the web.

The web and the branch can be formed integrally from sheet material.

The rear joint should have two rotational degrees of freedom, one for pivoting, under normal operation conditions, about an axis extending through the front and rear joints, the other allowing the web to swing backwards, once the branch is broken, whereby the wheel is pushed out of its wheel well.

In order to achieve a wide lateral displacement of the wheel, the wheel joint should be closer to the front joint than to the rear joint.

According to another embodiment of the invention, the object is achieved by a motor 15 vehicle in which a wheel, preferably a front wheel, is suspended by a control arm as defined above.

Here, in order to achieve a wide displacement of the wheel, the wheel joint may be located in front of the front and rear joints.

Further features and advantages of the invention will become apparent from the subsequent description of embodiments thereof, referring to the appended drawings:

Fig. 1 a perspective view from above of the control arm and surrounding components in a motor vehicle;

Fig. 2 a perspective view from below of of the control arm and surrounding components;

Fig. 3 a detail of the control arm; and

Fig. 4 top views of the control arm under normal operating conditions and after a crash.

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Fig. 1 is a perspective view showing parts of a subframe 1 of a motor vehicle, a lower control arm 2 attached to the subframe 1 by a front joint 3 and a rear joint 4, of a spring strut 5 and of a wheel bearing 6 wich, at its upper end, is attached to spring strut 5 and, at its lower end, to a wheel joint 7 of lower control arm 2. The joints 3,4 define an axis 23 by which the lower control arm 2 is free to pivot and which extends in the longitudinal direction of the motor vehicle, so that wheel bearing 6 is displaceable in the vertical direction. As can be seen more clearly in Fig. 4, the wheel joint 7 is closer to the front joint 3 than to the rear joint 4 and can even be located in front of the front joint 3.

The lower control arm 2 is shaped in one piece from a sheet metal blank. It comprises a web 8 which, regarded from above, extends arcuately between rear and wheel joints 4, 7 and a branch 9 which extends to front joint 3 from a branching portion 10 of web 8. The web 8 is widest in the vicinity of rear web and decreases in width approaching the wheel joint 7. The branch 9 is narrower than most, if not all, of web 8.

The cross section of web 8 is roughly in the shape of an upturned letter U, with a substantially horizontal central region 11 and sidewalls extending downwardly from the edges of central region 11. A stiffening corrugation 24 may extend at least along the wider parts of central region 11. One of said sidewalls 12 extends continuously between joints 4, 7. The other sidewall is divided into front and rear portions 13,14 by branch 9.

Branch 9, also being U-shaped in cross section, has a central region 15 which is level with central region 11 of web 8, and front and rear sidewalls 16,17. Front sidewall 16 extends in a straight line along with the sidewall front portion 13 of web 8. Rear sidewall 17 and sidewall rear portion 14 form a concavely curved edge of control arm 2, facing subframe 1.

As best seen in Fig. 2, the wheel joint 7 and the rear joint 4 have a structure different from that of front joint 3. Front joint 3 has a single degree of rotational freedom. Wheel joint 7 must have two in order to allow both for an up and down displacement and for a steering rotation of wheel bearing 6. Rear joint 4, having a design similar to that of wheel joint 7, also has two degrees of rotational freedom, but only one of > ·· • · · • · · ·

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these is used under normal operating conditions for the up and down movement of wheel bearing 6.

If the vehicle is involved in a shallow overlap front crash, the vehicle body in front of wheel bearing 6 is crushed, and a front wall 18 of a wheel well 19 will come to press against a wheel 20 attached to wheel bearing 6 (see Fig. 4). The web 8 is thus subjected to bending stress, and tensile stress is imposed upon branch 9, in particular its front sidewall 16.

io As shown in Fig. 3, a hole 21 is formed in the front sidewall 16 close to front joint 3. The hole 21 is elongate, with its longitudinal axis in an oblique orientation, rising towards front joint 3. The length of hole 21 is several millimetres, typically at least 5 mm, in this instance extending over approximately a third of the height of sidewall 16. The exact size of the hole 21 is optimized as a function of the rigidity of other components of the vehicle body likely to be affected by shallow overlap crash, so that if the crash is so vigorous that after crushing the body region in front of wheel well 19, there is enough energy left to affect a body region behind the wheel well 19, too, the branch 9 will yield to the tensile stress by a crack spreading from hole 21.

The hole 21 is pointed at its upper left corner, facing the joint 3, so that the crack will tend to set out from tip 22 and spread through sidewall 16 towards central region 15 and away from web 8, and will grow across central region 15 and rear sidewall 17 without affecting integrity of the web 8.

Once the branch 9 is completely broken, the web 8 is free to rotate about a vertical axis defined by rear joint 4, as shown in Fig. 4. By this rotation, the wheel 20 is pushed out of the wheel well 19, and the wheel well 19 and body regions adjacent to it, deprived of support by the wheel 20, are free to be crushed, too. Thus a considerably increased amount of collision energy can be absorbed by the front region of the vehicle body, reducing the risk of deformation of the passenger compartment.

It should be understood that the above detailed description and the drawings disclose specific embodiments of the invention, but that they are intended only for illustration purposes and must not be construed as limiting the scope of the invention. Various modifications of the described embodiments can be made within ··· ·· • · • · · ·· • · ···· ···« ·· ·· · the scope of the appended claims and their range of equivalents. In particular, from the description and the drawings, features may become apparent which are not mentioned in the claims. Such features may appear in other combinations besides those specifically disclosed here. The fact that several such features may be mentioned in the same sentence or in some other kind of contextual relation must not lead to the conclusion that they can only appear in the combination specifically disclosed; rather, it should be assumed that among such a plurality of features, one or more features can be left away or modified, as far as this does not jeopardize the correct operation of the invention.

List of References

5	1	subframe
	2	lower control arm
	3	front joint
	4	rear joint
	5	spring strut
10	6	wheel bearing

wheel joint web branch

		10 branching portion
	15	11 central region
		12 sidewall
·· • ·		13 sidewall front portion
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• 1 ·····		14 sidewall rear portion
• ·		15 central region
•	20	16 front sidewall
• · •		17 rear sidewall
• ·		18 front wall
»···		19 wheel well
···· •		20 wheel
······ • ·	25	21 hole
		22 tip
		23 axis
		24 corrugation

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Claims

Patent Claims

5 1. A control arm for use in a vehicle wheel suspension system, the control arm (2) comprising front and rear joints (3, 4) for pivotably connecting to a vehicle frame (1), a third joint (7) for connecting to a wheel (20), a web (8) extending between said rear and third joints (4, 7) and a branch (9) which extends from a branching portion (10) of said web (8) to said front joint (3), wherein a io breaking point is formed by locally weakening said branch (9).
2. The control arm of claim 1, wherein the branch (9) has front and rear sidewalls (16,17), and the breaking point is formed in the front sidewall (16).

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3. The control arm of claim 2, wherein the web (8) has a front sidewall (13) which extends in a straight line with the front sidewall (16) of the branch (9).
4. The control arm of claim 2 or 3, wherein the branch (9) has a U-shaped cross section, the sidewalls (16,17) forming the two sides of the U-shape.
5. The control arm of any of the preceding claims, wherein the breaking point is a cutout.
6. The control arm of claim 5, wherein the cutout is a hole (21).
7. The control arm of claim 6, wherein the hole (21) is elongate.
8. The control arm of any of claims 5 to 7, wherein the cutout is pointed at its upper end (22).
9. The control arm of claim 8, wherein the cutout points away from the web (8).
10. The control arm of any of the preceding claims, wherein the web (8) and the branch (9) are integrally formed from sheet material.
11. The control arm of any of the preceding claims, wherein the rear joint (4) has two rotational degrees of freedom.
12. The control arm of any of the preceding claims, wherein the wheel joint (7) is closer to the front joint (3) than to the rear joint (4).
13. A motor vehicle in which a front wheel (20) is suspended by the control arm

5 (2) of one of the preceding claims.
14. The motor vehicle of claim 13, wherein the wheel joint (7) is located in front of said front and rear joints (3,4).

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-10Intellectual

Property

Office

Application No: GB1618254.5 Examiner: Mr Kevin Hewitt