AUTOMOTIVE STEERING RACK SYSTEM WITH FIXED TOP ANTI-ROLL BAR BEARINGS

Abstract

A motor vehicle steering rack system comprising a rack housing (12) including fixings (20) on a vehicle cradle (2), a rack (26) sliding inside this housing (12) along a rack axis (A), and comprising two spaced bearings (22) of rotation of an anti-roll bar (24), fixed directly to one side of the housing (12), which are aligned along a bearing axis (B) parallel to the rack axis (A). Figure 3

Description

Title of the invention: AUTOMOBILE STEERING RACK SYSTEM WITH FIXED ANTI-ROLL BAR BEARINGS ON TOP

[0001] The present invention relates to a motor vehicle steering rack system comprising rotational guide bearings for an anti-roll bar which are fixed on it, as well as a motor vehicle equipped with such a rack system and a method of assembling this vehicle.

[0002] A known type of front axle for a motor vehicle, described in particular by document FR-A1-2922160, comprises an anti-roll bar arranged above a front axle cradle forming a highly rigid platform receiving the vehicle's suspension and chassis components, including the steering and suspension. The top of the cradle receives on each side a bearing for the rotation of the anti-roll bar, which is held in place by a flange covering it, fixed to the cradle by bolts passing through it.

[0003] The retaining bracket comprises an upward arm directed outwards from the vehicle, which terminates in a vertical cylinder receiving a bolt for securing the subframe under the vehicle body. The bracket thus constitutes a rigid element performing two functions, thereby avoiding the use of two separate parts: retaining the anti-roll bar bearing on the subframe and securing the subframe under the body. These functions require high strength to transmit potentially significant forces.

[0004] Furthermore, it is known to fix a steering rack housing to the subframe, controlling the pivoting of the front wheels, positioned parallel to the anti-roll bar, between the powertrain and the rear bulkhead separating the passenger compartment from the engine compartment. Depending on the vehicle's length, the mounting points are then successively those of the steering rack housing and those of the anti-roll bar guide bearings, each of these elements being fixed directly to the subframe, which requires successive longitudinal spaces for the two mounting points.

[0005] However, on some vehicles, the aim is to obtain in the engine compartment a mechanical assembly which, depending on the length, has a high compactness including better integration of this mechanical assembly, allowing for a short body.

[0006] In particular, electric traction powertrains with different geometries than those with internal combustion engines, arranged in front of the steering box and the separately fixed anti-roll bar, can give, along the axis The vehicle's longitudinal dimensions pose problems for achieving good compactness in the engine compartment.

[0007] The present invention is specifically designed to avoid these problems of the prior art.

[0008] For this purpose, it proposes a steering rack system for a motor vehicle comprising a rack housing including fixings on a cradle of the vehicle, and a rack sliding inside this housing along a rack axis, this system being remarkable in that it comprises two bearings spaced apart by rotation of an anti-roll bar, fixed directly on one side of the housing, which are aligned along a bearing axis parallel to the rack axis.

[0009] One advantage of this rack system is that by directly fixing the bearings of the anti-roll bar onto the housing which constitutes a rigid support linked to the cradle, there is no need to provide on the top of this cradle and next to the rack housing a specific location to receive the bearings.

[0010] A distance required to install the bearings with their fixing flanges on the cradle can be eliminated, and the axis of the anti-slip bar can be brought closer to that of the rack, which reduces the size of the mechanics along the longitudinal direction of the vehicle, and gives an engine compartment that can be shorter.

[0011] In addition, mass, assembly time and costs are limited by removing the bearing fixings on the cradle, which reduces the number of components.

[0012] A complete sub-assembly including the steering box equipped with the anti-roll bar fixed to it can also be prepared in advance, which is then brought to the vehicle assembly workshop.

[0013] The rack system according to the invention may further comprise one or more of the following features, which may be combined with each other.

[0014] According to one embodiment, the housing comprises for each bearing a form receiving a guide ring for the anti-roll bar which is directly made in the material of the housing.

[0015] In this case, advantageously the shapes are made by molding an aluminum alloy constituting the rack housing.

[0016] In particular, each bearing may include an added flange for retaining the guide ring.

[0017] Advantageously, the bearings are formed near the fastening devices on the vehicle cradle.

[0018] The invention also relates to a motor vehicle equipped with a steering rack which is part of a rack system comprising any one of the preceding characteristics.

[0019] In particular, the bearings can be formed on the side of the rack housing that is turned towards the front of the vehicle.

[0020] The motor vehicle may include an electric traction powertrain which is arranged in front of the rack housing.

[0021] The invention further relates to a method of assembling a vehicle comprising any one of the preceding characteristics, remarkable in that it includes a step of forming a sub-assembly equipped with the rack system with its anti-roll bar fixed on it, and then a step of assembling this sub-assembly in the vehicle.

[0022] The invention will be better understood and other features and advantages will become more apparent upon reading the following description given by way of example, with reference to the accompanying drawings in which:

[0023] [Fig. 1] shows in side view an electric traction powertrain arranged in front of a steering rack of a vehicle according to the prior art;

[0024] [Fig.2] shows this powertrain in a rear view; and

[0025] [Fig.3] shows in side view this powertrain arranged in front of a steering rack of a vehicle according to the invention.

[0026] Throughout the document, the upper or top direction is relative to a vehicle placed on a horizontal surface, the transverse direction is perpendicular to the longitudinal axis of the vehicle, the front direction AV is relative to its direction of travel.

[0027] Figures 1 and 2 show a cradle 2 receiving towards the front of the vehicle AV a powertrain 4 comprising an electric traction machine 6 disposed above the axis of the differential 8 driving shafts 10 connected to the drive wheels of the vehicle.

[0028] A steering column 16 passing through the passenger compartment apron by means of a sealing device 18, has a base fitting into a control housing 14 comprising a pinion which moves in a transversely elongated steering box a rack 26 aligned along a rack axis A.

[0029] The steering box 12 has two transversely spaced fixing systems 20, rigidly fixed on top of the cradle 2 in order to obtain a transmission of force which can be high between the steering column 16 and the steering wheels via the rack 26.

[0030] Typically, the fastening systems 20 include bosses formed by molding the body of the housing 12 in an aluminum alloy, which have vertical holes receiving screws through the cradle 2 to tighten this housing on top of the cradle.

[0031] An anti-roll bar 24 comprises a straight part aligned transversely, guided by two bearings 22 including a rotating ring, fixed by bearing flanges above the cradle 2 between the steering box 12 and the powertrain 4, this straight part extending at each end by a curved part 26 connected to a suspension element to control its travel.

[0032] It is then necessary to provide, according to the longitudinal direction of the vehicle, a space between the powertrain 4 and the steering box 12 giving a first distance DI between the axis of the bar A and the axis of the anti-roll bar B, plus a second distance D2 between this axis of the rack and the axis of the differential 8 of this group.

[0033] Figure 3 shows a steering box 12 comprising on its front side two bosses 30 spaced apart along the transverse direction, which are formed directly by an extension of the casting of this box. Each of the bosses 30 has a hole receiving a guide ring for a bearing 22 of an anti-roll bar 24, these two bearings being aligned along the transverse direction of the vehicle to receive the right-hand part of this bar.

[0034] Alternatively, the housing 12 may include for each bearing 22 a cradle shape receiving a guide ring for the anti-roll bar 24, directly made in the molding of the housing material, and then a fixing clevis for this ring which surrounds it.

[0035] Advantageously, the bosses 30 of the bearings 22 are placed near the fixing systems 20 on the cradle 2 to obtain a direct connection and high rigidity between these bearings and the cradle.

[0036] Integrating the bearing bosses 30 into the steering housing 12 allows the bearing axis B to be machined as close as possible to the axis of the rack A, resulting in a reduced initial distance Dl' along the longitudinal direction of the vehicle, which is the smallest possible. This leads to a reduced total distance Dl' plus D2', and the powertrain 4 is moved further back in the engine compartment, which can be shorter.

[0037] Integrating the bearing bosses 30 directly into the steering housing 12 during its molding also allows at least part of the rotating ring surround to be formed within this boss. Furthermore, it is not necessary to provide a reinforced location on the cradle 2 to receive the bearing 22 fasteners.

[0038] The number of parts used can be limited, the mass of the assembly reduced, and the number of assembly operations decreased. This results in a reduction in the costs of supplying parts and assembly labor.

[0039] Furthermore, for vehicle assembly, a sub-assembly can be prepared comprising the steering box 12 fully equipped with its rack 26, which receives the anti-roll bar 24 held by its bearings 22 on this box. This sub-assembly is delivered to the vehicle assembly workshop. This reduces the number of sub-assemblies to be supplied to this workshop and fitted to the vehicle, thus simplifying the final vehicle assembly operations.

Claims

Demands

1. A motor vehicle steering rack system comprising a rack housing (12) including fixings (20) on a vehicle cradle (2), and a rack (26) sliding inside this housing (12) along a rack axis (A), characterized in that it comprises two spaced bearings (22) of rotation of an anti-roll bar (24), fixed directly on one side of the housing (12), which are aligned along a bearing axis (B) parallel to the rack axis (A).

2. Rack system according to claim 1, characterized in that the housing (12) comprises for each bearing (22) a form receiving a guide ring for the anti-roll bar (24), which is directly made in the material of the housing (12).

3. Rack system according to claim 2, characterized in that the shapes are made by molding an aluminum alloy constituting the rack housing (12).

4. Rack system according to claim 2 or 3, characterized in that each bearing (22) has an added flange for retaining the guide ring.

5. Rack system according to any one of the preceding claims, characterized in that the bearings (22) are formed near the fixings (20) on the vehicle cradle (2).

6. Motor vehicle equipped with a steering rack (26), characterized in that this rack (26) is part of a rack system according to any one of the preceding claims.

7. Motor vehicle according to claim 6, characterized in that the bearings (22) are formed on the side of the rack housing (12) which is turned towards the front of the vehicle.

8. Motor vehicle according to claim 7, characterized in that it comprises an electric traction powertrain (4) which is arranged in front of the rack housing (12).

9. A method of assembling a vehicle according to any one of claims 6 to 8, characterized in that it comprises a step of forming a sub-assembly comprising the rack system with its anti-roll bar (24) fixed thereon, and then a step of assembling this sub-assembly in the vehicle.

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