GB2301564A

GB2301564A - Steering system for a motor vehicle

Info

Publication number: GB2301564A
Application number: GB9610807A
Authority: GB
Inventors: Karl Peitsmeier; Helmut Flemming; Alfred Schnabel; Gerd Willy
Original assignee: Daimler Benz AG; Mercedes Benz AG
Current assignee: Daimler Benz AG
Priority date: 1995-05-30
Filing date: 1996-05-23
Publication date: 1996-12-11
Anticipated expiration: 2016-05-23
Also published as: IT1285126B1; ITRM960274A0; GB2301564B; ITRM960274A1; FR2734780B1; DE19519664A1; GB9610807D0; FR2734780A1

Description

1 Steering system for a motor vehicle 2301564 The invention relates to a

steering system for a motor vehicle, with a steering spindle which is connected, with a steering coupling interposed, to a steering gear arranged on a frame component which comes loose from the vehicle at an early stage in the event of a collision.

It is known from German Offenlegungsschrift 2,750,179 to provide a motor vehicle with a crossmember for a front-wheel suspension, a steering gear of a steering system for the motor vehicle being fastened to the said crossmember. The crossmember is connected to the engine of the motor vehicle in such a way that, in the event of a crash of the motor vehicle, the weight of the engine shears off the crossmember and therefore the steering gear downwards at an early stage. This is intended to reduce considerably or prevent a backward movement of the upper part of the steering rod in the event of a crash.

It is also known (Mercedes passenger cars) to arrange an engine and a front-wheel suspension of a motor vehicle, including a steering gear, on an integral crossmember which is fastened to two frame side members of the supporting structure of the motor vehicle in such a way that the said crossmember comes loose from the frame side members at an early stage in the event of a vehicle collision. Depending on the constructive design of the steering, that is to say, in particular, of the steering spindle, however, in the event of such a collision the steering gear is pushed back so far that the telescopic capacity of the steering is no longer sufficient to prevent an inadmissible displacement of the steering wheel into the interior. This problem arises particularly when a lower steering spindle of the steering is executed in a design appropriate for aluminium.

The present invention seeks to provide a steering system of the type mentioned in the introduction, which, even with a reduced telescopic capacity of the steering spindle, ensures sufficient safety for the driver of the motor vehicle in the event of a collision of the motor vehicle.

2 According to the present invention there is provided a steering system for a motor vehicle, with a steering spindle which is mounted in a steeringcolumn tube and the lower part of which is connected, with a steering coupling interposed, to a steering gear arranged on a frame component which comes loose from the vehicle body at an early stage in the event of a collision, wherein the steering spindle is assigned, adjacent the steering coupling, a restraint device arranged fixedly relative to the vehicle body and which engages without contact behind the steering coupling, in relation to the longitudinal direction of the vehicle, and is such that, in the event of a collision, it absorbs forces introduced into the steering coupling as a result of a back-ward displacement of the steering gear, until the steering gear is uncoupled from the vehicle body.

This restraint device is made so stable that it absorbs the forces introduced during the backward displacement of the steering gear in the event of a crash, until uncoupling takes place between the steering gear and the steering spindle as a result of the forces occurring. The essential postulation according to the invention in this solution is that relative movement takes place between the steering gear and the restraint device. In particular, the integral crossmember coming loose at an early stage from the supporting frame of the motor vehicle is already bringing about a backward and downward displacement of the steering gear as long as the restraint device attached to the still stable part of the body has not yet executed any backward movement. The steering coupling and therefore the steering spindle are thus still supported and restrained in a stable manner while the steering gear is already being displaced backwards, with the result that the steering gear is uncoupled from the steering coupling or the steering spindle at predefined desired breaking points. It is thereby possible, by means of the restraint device, to cancel forces which lead to an uncoupling of the steering gear, without inadmissibly high forces and long travels being transmitted via the lower steering spindle to the steering-column-tube assembly of the steering system and consequently into the vehicle interior.

In one embodiment of the invention, the restraint device has a restraining loop which is fastened to the frame side member and which 3 surrounds the steering coupling without contact at a distance allowing all the movements of the steering coupling which occur during driving. This restraining loop is fastened to the frame side member in a position which, in the event of a crash, is displaced back-wards only some time after the integral member has come loose. Due to the fact that the restraining loop surrounds the steering coupling at a distance, the functioning of the steering system is not impaired.

In a further embodiment of the invention, the restraining loop consists of metal and is designed as a tube or as a pull means, particulary as a rope or chain. This is a particularly stable and simple embodiment.

Exemplary embodiments of the invention will now be described by way of example with reference to the drawings, in which:- Fig. I shows a top view of a bodyshell structure of a motor vehicle in the region of one embodiment of a steering system according to the invention which is assigned a restraint device in the form of a restraining plate, Fig. 2 shows a side view of the bodyshell structure according to Fig. I provided with the steering system, Fig. 3 shows a top view of a further embodiment of a steering system according to the invention, in which a metal loop is provided as a restraint device, and Fig. 4 shows a side view of the steering system according to Fig. 3 arranged in the bodyshell structure. A motor vehicle according to Figs. I to 4 has a bodyshell structure which is provided, in a front region, with two frame side members I extending in the longitudinal direction of the vehicle. To the rear, the two frame side members I adjoin a bulkhead 2. For the sake of clarity, only parts of the bodyshell structure are represented in Figs. I to 4, and also only one individual frame side member I arranged in front of the driver's side of the motor vehicle is shown. An integral crossmember 3, on which an engine is held in a way not shown, extends in the region of the forward structure, between the two side members 1. This crossmember 3 is connected from below to the two frame side 4 members 1, and, in the event of a collision of the vehicle, it comes loose from the frame side members 1, before the frame side members 1 are deformed in the region of the fastening points of the integral crossmember 3. A front-wheel suspension, including the associated parts of a steering system, is held on the crossmember 3. A steering gear 6, which is connected to the crossmember 3, is shown particularly in more detail as part of the steering system. The steering gear 6 is connected, with a steering coupling 5 interposed, to a lower part of a steering spindle 4 which projects through a bulkhead 2 of the bodyshell structure into a passenger compartment and which is mounted in a steering-column- tube assembly 8 arranged fixedly relative to the passenger compartment. A steering wheel is attached, in a way not shown, onto that end face of the steering spindle 4 which projects into the interior of the passenger compartment.

The lower part of the steering spindle 4 is designed as an alu construction. This results in a telescopic capacity which is reduced in comparison with steel constructions. In order, in the event of a crash, to prevent the reduced telescopic capacity of the steering spindle 4 from leading to an inadmissible displacement of the steering wheel into the vehicle interior, the steering system is assigned, level with the steering coupling 5, a restraint device in the form of a restraining plate 7 Figs. 1 and 2. This restraining plate 7 is designed with the stability of a board and, in the region of the bulkhead 2, level with the steering coupling 5, is arranged horizontally in such a way that it engages at a distance behind the steering coupling 5. The restraining plate 7 is welded in a stable manner both by spot welding to the bulkhead 2 and, on a carrier part drawn forwards, to the frame side member 1 in the region of fastening points 9. The rigidity of the restraining plate 7 is designed in such a way that, in the event of a crash, it can support the steering coupling 5 in a stable manner counter to forces introduced as a result of a backward displacement of the steering gear 6. The forces introduced by way of the steering gear 6 result from the fact that the crossmember 3, including the engine, already comes loose from the frame side member 1 when the frame side member 1 is not yet deformed at all in the region of the fastening points of the crossmember 3 and, in particular, in the region of the fastening points 9 of the restraining plate 7. The restraining plate 7 therefore induces a notching or buckling effect which causes the steering gear 6 to be uncoupled from the steering spindle 4. A displacement of the steering spindle 4 into the vehicle interior is thus avoided.

The motor vehicle according to Figs. 3 and 4, including its steering system, corresponds to the previously described motor vehicle according to Figs. I and 2. The only difference in the embodiment according to Figs. 3 and 4 is that the restraint device provided for the steering coupling 5 is a restraining loop 7a which is designed as a metal loop in the form of a bent tube. This restraining loop 7a surrounds the steering coupling 5 without contact, the distance of approximately 15 mm between the restraining loop 7a and the steering coupling 5 being so great all-round that the functioning of the steering system in the event of a rotation of the steering wheel is not impaired. The ends of the restraining loop 7a are fixedly connected, level with a rear holding point of the integral member 3, to the frame side member 1. A fastening point 9a for fastening the restraining loop 7a to the frame side member I is thus provided approximately level with the fastening of the crossmember 3 to the frame side member 1, the crossmember 3 undertaking the mounting of the engine. The fastening point 9a of the restraining loop 7a, like the fastening points 9 of the restraining plate 7, is therefore selected in such a way that, in the event of a crash, the crossmember 3, including the steering gear 6, is displaced backwards laterally long before the frame side member 1, level with this fastening point 9a. The restraining loop 7a is screwed to the frame side member I in the region of the fastening point 9a. Unreleasable fastenings of the restraining loop 7a are also provided, however, in the same way. Depending on constructive requirements, it is possible to connect the stable restraining loop 7a to the frame side member 1, with a reinforcing plate interposed.

6

Claims

ClaiMs

1. A steering system for a motor vehicle, with a steering spindle which is mounted in a steering-column tube and the lower part of which is connected, with a steering coupling interposed, to a steering gear arranged on a frame component which comes loose from the vehicle body at an early stage in the event of a collision, wherein the steering spindle is assigned, adjacent the steering coupling, a restraint device arranged fixedly relative to the vehicle body and which engages without contact behind the steering coupling, in relation to the longitudinal direction of the vehicle, and is such that, in the event of a collision, it absorbs forces introduced into the steering coupling as a result of a backward displacement of the steering gear, until the steering gear is uncoupled.

2. A steering system according to Claim 1, wherein the restraint device has a rigid restraining plate which is fastened, adjacent the steering coupling, in the region of a bulkhead to a frame side member of the motor vehicle.

3. A steering system according to Claim 1, wherein the restraint device has a restraining loop which is fastened to the frame side member and which surrounds the steering coupling without contact at a distance which allows all the movements of the steering coupling which occur during normal driving.

4. A steering system according to Claim 3, wherein the restraining loop consists of metal and comprises a tube.

5. A steering system according to Claim 3, wherein the restraining loop consists of a rope or chain.

6. A steering system for a motor vehicle, substantially as described herein with reference to, and as illustrated in, the accompanying drawings.