GB2349856A

GB2349856A - Vehicle air suspension

Info

Publication number: GB2349856A
Application number: GB0011158A
Authority: GB
Inventors: Gary Lee Smith; Paul John Griffiths
Original assignee: Meritor Heavy Vehicle Systems Ltd
Current assignee: Meritor Heavy Vehicle Systems Ltd
Priority date: 1999-05-10
Filing date: 2000-05-10
Publication date: 2000-11-15
Anticipated expiration: 2020-05-10
Also published as: GB9910697D0; GB2349856B; GB0011158D0

Abstract

A longitudinal member, e.g. a leaf spring (11), of a vehicle air suspension which carries an air spring (23) and is pivoted at a front end portion (12) between opposed sides (14, 15) of a bracket (10) which is secured for use to a vehicle, has a width of 70-80mm. The bracket is generally parallel-sided and has a width at the top not exceeding 100mm. These dimensions of the longitudinal member (11) and bracket (10) enable the bracket to be connected directly to the chassis, more particularly to a chassis flange the width of which may vary, typically, between 100 and 150mm. Thus the need for an adapter plate or for reducing the width of the top of the bracket, as has been necessary for a conventional longitudinal member typically 100mm wide, is avoided.

Description

2349856 AIR SUSPENSIONS FOR VEHICLES This invention relates to air

suspensions for vehicles of the type comprising at least one bracket which is secured to and depends from one side of a vehicle, at least one longitudinal member which extends lengthwise of the vehicle, is pivotally mounted at a front end portion to the bracket and carries an air spring rearwards of said front end portion so that the air spring acts between the vehicle and the longitudinal member, and an axle for rotatably mounting a wheel or wheels is secured to the longitudinal member rearwards of said front end portion. Such air suspension is hereafter referred to as "an air suspension of the type described".

The axle may be a stub axle. Alternatively, the suspension may comprise two of the brackets which are aligned, one depending from each side of the vehicle, each bracket having, extending lengthwise of the vehicle, one of the longitudinal members which is pivotally mounted at a front end portion of the bracket with the air spring it carries being rearwards of said front end portion so that the air spring acts between the respective longitudinal member and the vehicle. In this arrangement there may be the one axle which extends between and beyond the longitudinal members and is secured thereto rearwards of said front end portions.

In an air suspension of the type described, a non-limiting example of which is a suspension fitted to an articulated trailer vehicle, the or each bracket is generally U-shaped in plan and of metal plate construction having two sides which are joined at their front edges by a front plate and having a closing plate at the rear. The or each longitudinal member, generally a substantial leaf type spring of substantially 100mm width, has an eye end, which accommodates a bearing bush, and is received between 2 the sides of the, or the respective, bracket at its lower end. A securing member, for example a long bolt, passes through registering holes in the, or the respective, bracket and the bush to secure the assembly for pivoting movement of the, or the respective, longitudinal member under the control of the air spring carried by that member and, usually, a shock absorber.

With this arrangement just described the distance between the sides of the or each bracket at its lower end has to be in excess of 100mm and the overall width is commonly of the order of 125mm. Trailer chassis flanges vary in width between about 100 and 150mm. Accordingly, a parallel-sided bracket is secured to a narrow chassis flange either by fillet welding or indirectly by way of an adapter plate - butt welding direct to the flange is not practicable unless the flange width is about 125mm or more. Alternatively, it is known for the or each bracket to be joggled whereby its width towards the top is less than its width at the bottom, to facilitate securing directly to the chassis of a vehicle.

It is proposed, by this invention, to remove the above-mentioned constraints and at the same time provide an air suspension of similar or better performance which is also significantly lighter, thus reducing unsprung weight and allowing greater payloads.

According to a first aspect of the present invention an air suspension for a vehicle of the type described is provided which comprises a longitudinal member of a width in the range of 70 to 80mm in conjunction with a generally parallel-sided bracket the width of which at the top does not exceed 100mm, whereby the bracket is adapted for direct connection to the chassis of a vehicle.

3 Preferably shock absorber means are connected between the bracket and the means securing the stub axle or axle (as the case may be), and longitudinally aligned with the bracket and member.

Preferably the sides of the bracket at the top are bevelled to facilitate butt welding to the chassis of a vehicle.

Preferably, having the width of the longitudinal member between 70 and 80mm, suitably 75mm, the depth of the member is increased beyond that of longitudinal members used in common practice so as to maintain stresses in the member equivalent to those in members used in current practice. This results in a longitudinal member which is significantly lighter than the longitudinal members used in current practice.

The longitudinal member may comprise a leaf spring.

A decrease in width, with current materials, below about 70mm together with the corresponding increase in depth leads to excessive stiffness of the spring, requiring supplementary compliance to be introduced elsewhere in the suspension to compensate. A width above about 80mm causes an increase in width of the bracket beyond the limit necessary to permit butt welding direct to a narrow chassis, unless the bracket is joggled.

According to a second aspect of the present invention a leaf spring is provided having a width of between 70 and 80mm and adapted for use in an air suspension in accordance with the first aspect of the invention hereinafter set forth.

An embodiment of the invention will now be described by way of example only with reference to the accompanying drawings, in which:

4 Figure 1 illustrates a known bracket for an air suspension and Figure 2 is an exploded view of the components of an air suspension according to the present invention.

Referring to Figure 1, a known hanger bracket 1 comprises a pressed and fabricated bracket having sides 2, 3 and a front plate 4. A rear closing plate, not shown, is welded between the side plates adjacent their rear edges and extending from the top down past the joggled section to the region of the slotted holes 5. The distance between the sides 2, 3 past the joggled section is determined by the width of a leaf spring to be pivotally supported by a bolt passing through the aligned slots 5 and a bearing bush in an eye of the spring. The slots are provided for alignment purposes.

Aligned bosses may be provided, for example at the joggled section, for mounting one end of a telescopic shock absorber.

Conventionally, and as an industry standard, the leaf spring has a width of substantially 10Omm.

Referring now to Figure 2, an air suspension in accordance with the present invention is shown which comprises a hanger bracket 10, and a leaf spring 11 the width of which is between 70 and 80mm, conveniently 75mm. The leaf spring 11 has a front end portion formed as an eye end 12 in which a bearing bush 13 is engaged.

The hanger bracket 10 has opposed parallel flat sides 14, 15 which are joined by a front section 16 and a rear closing plate 17. The sides 14, 15 have bevelled top edges 15A. The width of the hanger bracket 10 between the parallel sides 14, 15 is such as to receive the leaf spring 11 but does not exceed 100mm. Opposed lugs 18 at the rear of the hanger bracket provide a mounting for an upper end of a shock absorber 19.

The eye end 12 of leaf spring 11 is entered between the sides 14, 15 of the bracket 10 so that it is in register with aligned holes towards the bottom of the sides and is secured for pivotal movement by a bolt 20.

The other (rear) end of leaf spring 11 incorporates a platform 21 to which a piston 22 for an air spring 23 is secured, as by bolts 24. An upper end of the air spring 23 is secured by way of an adapter plate 25 to a vehicle, not shown. A through hole 26 (or aligned recesses in upper and lower surfaces) in the leaf spring I I is provided for location by dowels 27 of a spring seat 28 and a top plate 29 whereby an axle (not shown) may be secured to the leaf spring 11 by U-bolts 31. Anti-fretting inserts 32 are provided between the spring 11 and the spring seat 28 and top plate 29.

The top plate 29 has lugs 33 for pivotally mounting the lower end of shock absorber 19 thereon.

Claims

6 CLAIMS

1 An air suspension for a vehicle of the type described which comprises a longitudinal member of a width in the range of 70 to 80mm in conjunction with a generally parallel-sided bracket the width of which at the top does not exceed 10Omm, whereby the bracket is adapted for direct connection to the chassis of a vehicle.

2. An air suspension as claimed in claim 1 wherein the depth of the longitudinal member is increased beyond that of longitudinal members used in current practice so as to maintain stresses in the member in use equivalent to those in members used in current practice.

3. An air suspension as claimed in claim 1 or claim 2 in which the sides of the bracket at the top are bevelled to facilitate butt welding to the chassis of a vehicle.

4. An air suspension as claimed in any preceding claim wherein the longitudinal member comprises a leaf spring.

5. An air suspension as claimed in any preceding claim wherein means are provided for securing an axle to the longitudinal member, said means comprising co-operating locating means between the member and a plate component and a spring seat component, one above and one below the member, the spring seat component being adapted to receive an axle, and means to clamp said plate and spring seat components, and the axle received by the spring seat component when in use, in aligned relationship to the member.

7 6. An air suspension as claimed in claim 5 wherein the locating means comprises a through hole in the member, locating recesses in the plate component and the spring seat component and a dowel or like member which extends through the hole and engages in the recesses.

7. An air suspension as claimed in claim 5 wherein the locating means comprises aligned recesses in upper and lower surfaces of the longitudinal member, corresponding recesses in the mating surfaces of the plate component and the spring seat component, and dowels or like members arranged to be received in the respective recesses to locate in alignment the plate component, member and spring seat component.

8. An air suspension as claimed in any of claims 5, 6 or 7 including shock absorber means connected between the bracket and either the plate component or the spring seat component.

9. An air suspension for a vehicle substantially as described herein with reference to Figure 2 of the accompanying drawings.

10. A vehicle having an air suspension as claimed in any preceding claim.

11. A leaf spring having a width of between 70 and 80mm and adapted for use in an air suspension as claimed in any of claims 1 to 8.