WO2009087661A1

WO2009087661A1 - Steering arm mounting system and method of mounting thereof

Info

Publication number: WO2009087661A1
Application number: PCT/IN2008/000786
Authority: WO
Inventors: Hari Srinivas Babu Aggarapu; Swapnil R. Salunkhe
Original assignee: Tata Motors Limited
Priority date: 2008-01-08
Filing date: 2008-11-26
Publication date: 2009-07-16
Also published as: ZA201005212B

Abstract

This invention relates to a steering arm (16) and a method of mounting a steering arm (16) for a vehicle comprising: a preferably L-shaped structure bent along a bend plane (12); said structure having a substantially uniform thickness throughout and substantially uniform bend radius to minimize the stress raisers; said L-shaped structure having a top portion substantially horizontal and a vertical portion; an insert (10) with a tapered hole (15) is provided on the top portion of said structure to accommodate a ball joint from steering rack and pinion tie-rod; plurality of mounting apertures (11) are provided on the vertical portion of the L-shaped structure such that the said steering arm (16) is independently mountable with a knuckle arrangement onto a suspension strut (13) mounting bracket.

Description

STEERING ARM MOUNTING SYSTEM AND METHOD OF MOUNTING THEREOF

FIELD OF INVENTION

This invention relates generally to a Steering arm and more particularly to a sheet metal type steering arm mounting system and method of mounting thereof.

BACKGROUND OF THE INVENTION

Conventionally, Steering arms for automobiles have been manufactured either by casting or forging and are integral part of steering knuckles. Steering arm integrated with steering knuckle manufactured in casting or forging are basically designed to provide the required strength & stiffness to withstand various loads encountered by steering arm during various steering maneuverings. However, the complexity and cost of such cast or forged knuckles with integrated steering arms is quite high for the following reasons:

1) Requirement of subsequent machining operation to achieve close tolerance limits.

2) Integral steering arm requires complex mould, thereby contributing to additional cost.

3) Increased weight of the knuckle conversely requires the other mating steering/suspension parts to be made heavier to withstand the combined loads of steering knuckle integrated with steering arm.

In the past, various attempts have been made to reduce the complexity by fabricating steering knuckles from sheet metal with integrated steering arm. US 4674760 and US 3865394 teach a unitary sheet metal knuckle with integral steering arm. However the major drawback associated with said unitary sheet metal knuckle is that it is a vehicle specific and which will not completely address the above said drawbacks.

In order to overcome the said drawbacks, this steering arm is devised.

OBJECTS OF INVENTION

The main object of this invention is to provide a steering arm mounting system which is capable of mounting independently on to a steering knuckle.

Yet another object of this invention is to provide Steering arm mounting system which can be easily accommodated in different variety of vehicles in a similar category.

Yet another object of this invention is to provide Steering arm mounting system and method of mounting thereof that requires fewer machining operations compared to cast /forged assemblies.

Yet another object of this invention is to provide Steering arm mounting system and method of mounting thereof which is capable of providing desired shapes to enhance the rigidity of the entire steering system.

Yet another object of this invention is to provide Steering arm mounting system and method of mounting thereof which is simple in construction and cost effective. Yet another object of this invention is to provide Steering arm mounting system and method of mounting thereof which is easy to install & maintain.

BRIEF DESCRIPTION OF INVENTION

Steering arm mounting system in accordance with this invention basically comprises of an independent sheet metal element that can be mounted to the knuckle through the same mounting as used for suspension strut and also that can be designed to any desirable shape & dimension without touching the other peripheral parts in case of increased steering loads based on increment in front axle weight (FAW) of the vehicle for reasons depicted by market requirements. The sheet metal steering arm is preferably L-shaped structure with uniform thickness through-out. However, for the purpose of mitigating stresses at the bent plane, the steering arm is provided with uniform bend radius sufficient to minimize the stress raisers.

The independent sheet metal steering arm comprises of a sheet metal with uniform thickness with a bend plane provided with an insert and with a tapered hole at one end to accommodate the steering tie rod ball joints. Said steering arm is also provided with plurality of holes in line with knuckle holes for mounting the steering arm on said knuckle through the holes that are common with the suspension strut mounting. Said steering arm is provided with curvilinear profile near said tapered insert to have sufficient rigidity and to avoid fouling during maneuvering with other vehicle parts near the vicinity of it.

This invention aims at providing a sheet metal steering arm that is capable of mounting independently to the steering knuckle and can be used with various steering knuckles without affecting the design of the steering knuckle. BRIEF DESCRIPTION OF DRAWINGS

Fig.l shows an isometric view of the assembly Knuckle with mounting arrangement of independent sheet metal steering arm mounted on brake drum.

FIG.2 shows an exploded perspective view of assembly Knuckle with mounting arrangement of independent sheet metal steering arm and brake drum.

FIG.3 shows sheet metal steering arm of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

Referring now to the drawings wherein the showings are for the purpose of illustrating a preferred embodiment of the invention only, and not for the purpose of limiting the same,

Referring figures 1 to 3, Steering arm mounting system in accordance with this invention basically comprises of an independent sheet metal element that can be mounted to the knuckle through the same mounting as used for suspension strut and also that can be designed to any desirable shape & dimension. The sheet metal steering arm (16) is preferably L-shaped structure with uniform thickness throughout. However, for the purpose of mitigating stresses at the bend plane, the steering arm is provided with uniform bend radius sufficient to minimize the stress raisers.

From the several figures of the drawings ,one side of the vehicle suspension is shown in FIG.l having a suspension strut(13), the top of which is connected to the vehicle structure (not shown in figure) and the bottom is provided with sheet metal welded bracket(14) that is mounted through nut and bolt(7) on a forged knuckle(2). The top of the forged knuckle(2) is provided with an extended flange(2a) on which the suspension strut(13) is mounted using nut & bolt(7) arrangement and bottom of the knuckle(2) is provided with another extended flange(2b) with a slit at the centre of the flange. Through the slit (21) is provided a ball stud (4) of lower suspension ball joint (5). The stud (4) is housed in a forged housing (5) having a rubber boot (20) as a protective cap for prevention of mud & slurry from entry in to the ball joint during vehicle operation. The ball stud (4) and rubber boot (20) are housed in an assembly, welded to an extended flange (22) with two holes. This extended flange with two holes is riveted (19) on a sheet metal lower control arm (23) provided with a typical extended structure equipped with bushes (9) at the end. The lower control arm (23) is mounted to the car body using the bushes (9) provided. The knuckle (2) is equipped with 4 holes (18) that can be used for mounting the brake drum assembly (6) using bolts (8). The outer side of the knuckle (2) is equipped with a tapered shaft (1) on which a wheel bearing is assembled.

The steering arm (16) is fabricated by a sheet metal structure. Steering arm (16) is made out of uniform thickness sheet metal that is bent along a bend plane (12) to avoid fouling of the tie rod during various maneuvering events. Also the bending (12) is achieved to avoid any stress raisers that araise on the sheet metal steering arm (16) during cold bending. The L-shaped steering arm is having two portions, a substantially horizontal portion and a vertical portion. The horizontal portion will be formed as top side of the steering arm on assembling. A hole is provided on top side of the sheet metal steering arm to locate an insert (10) with tapered hole (15). The insert is welded to the steering arm hole all around. This tapered hole (15) is used to accommodate the ball joint from the steering rack & pinion tie-rod. The steering rod end ball joint is retained in position by means of a nut. The steering tie rod is pushed in & out to allow articulation of the wheel mounted thereto when the steering wheel is rotated clockwise & counter clockwise. A nut is secured to the steering tie rod ball joint end which is extended through the steering arm (16) having a provision to accommodate the same. This ball joint end is a part of the steering rack & pinion tie rod end. The tie rod is a part of the rack & pinion assembly which is mounted on the vehicle structure directly or by using a sub-structure. On the vertical portion of the steering arm (16), two uni-dimensional holes are provided for mounting the same. The steering arm width (17) is maintained the same as that of the strut mounting bracket width.

Method of Mounting of Steering Arm comprises of

1) Mounting the suspension strut (13) at the top of the vehicle structure using suitable mountings with the other end of the suspension strut (13) mounted to the knuckle (2) provided with two holes (11).

2) The sheet metal steering arm placed over the suspension strut mounting (3) in a direction that is feasible for the assembly of the tie rod outer ball joint.

3) Steering arm (16) is assembled using the same bolts (7) that are used for mounting the suspension strut (13) to the knuckle (2), such that the steering arm (16), suspension strut (13) are mounted together using single mounting (7) arrangement.

The sequence of assembly of the steering arm is as illustrated in exploded view as shown in FIG.2.

The foregoing description is a specific embodiment of the present invention. It should be appreciated that this embodiment is described for purpose of illustration only, and that numerous alterations and modifications may be practiced by those skilled in the art without departing from the spirit and scope of the invention. It is intended that all such modifications and alterations be included insofar as they come within the scope of the invention as claimed or the equivalents thereof.

Claims

1. A steering arm for a vehicle comprising: a preferably L-shaped structure bent along a bend plane, said structure having a substantially uniform thickness throughout and substantially uniform bend radius to minimize the stress raisers; said L-shaped structure having a top portion substantially horizontal and a vertical portion; an insert with a tapered hole is provided on the top portion of said structure to accommodate a ball joint from steering rack and pinion tie-rod; plurality of mounting apertures are provided on the vertical portion of the L- shaped structure such that the said steering arm is independently mountable with a knuckle arrangement onto a suspension strut mounting bracket.

2. The steering arm as claimed in claim 1, wherein the steering arm is fabricated by a sheet metal structure.

3. The steering arm as claimed in claim 1, wherein said steering arm is provided with a curvilinear profile near said tapered insert to have sufficient rigidity and to avoid fouling during maneuvering with other vehicle parts near its vicinity.

4. The steering arm as claimed in claim 1, wherein the steering arm has a width that is substantially same as that of the suspension strut mounting bracket width.

5. A steering arm mounting system for a vehicle comprising, a suspension strut with a top and bottom part; said top part being connected to a vehicle structure and said bottom part is provided with a mounting bracket; a steering arm as claimed in claims 1 to 4; a knuckle arrangement for assembly with a brake drum assembly and a wheel bearing said knuckle having a top extending flange and a bottom extending flange; wherein said steering arm is independently mountable with said top extending flange of said knuckle arrangement onto said suspension strut mounting bracket.

6. The steering arm mounting system as claimed in claim 5, wherein a slit is provided at the centre of the bottom extending flange of said knuckle arrangement.

7. The steering arm mounting system as claimed in claim 6, wherein said slit houses a ball stud of a lower suspension ball joint.

8. The steering arm mounting system as claimed in claim 7, wherein a rubber boot is provided proximal to the ball stud as a protective cap for prevention of mud and slurry from entry in to the ball joint during vehicle operation.

9. A method of mounting a steering arm comprising the steps of: mounting a top end of a suspension strut to a vehicle structure; mounting a knuckle arrangement, having a top extending flange and a bottom extending flange, onto an extending bracket provided at a bottom end of the suspension strut; placing a steering arm as claimed in claims 1 to 4 over the top extending flange of the knuckle arrangement in a direction that is feasible for the assembly of a tie rod outer ball joint; fastening said steering arm, knuckle arrangement and suspension strut using fastening means such that said steering arm is mounted independently with said knuckle arrangement onto the extending bracket of said suspension strut.

10. A steering arm for a vehicle as hereinbefore described with reference to the accompanying drawings.

11 A steering arm mounting system for a vehicle as hereinbefore described with reference to the accompanying drawings.

12 A method of mounting a steering arm as hereinbefore described with reference to the accompanying drawings.