WO1989005242A1

WO1989005242A1 - Support for a suspension spring for a steerable vehicle wheel

Info

Publication number: WO1989005242A1
Application number: PCT/SE1988/000668
Authority: WO
Inventors: Michal Brokholc
Original assignee: Volvo AB
Current assignee: Volvo AB
Priority date: 1987-12-10
Filing date: 1988-12-08
Publication date: 1989-06-15
Anticipated expiration: 1990-06-10
Also published as: SE459727B; SE8704940D0; SE8704940L

Abstract

A spring mounting for MacPherson-type spring strut. The mounting comprises a plastic upper spring seating (19) which is configured to serve also as holder for the upper strut bearing (18). The spring seating support surface comprises a plurality of surface parts (23) formed on tongues (21) and distributed sequentially in the winding direction of the spring (20).

Description

Support for a suspension spring for a steerable vehicle wheel

The present invention relates to an arrangement for mounting and journalling a spring strut which is intended for a steerable vehicle wheel and which includes a shock absorber and a helical spring which surrounds the shock absorber and is mounted in the vehicle body, said arrange¬ ment comprising means for resiliently mounting the upper end of the piston rod of said shock absorber in the ve¬ hicle body, an upper spring seating having a support surface which is adapted to conform to the upper turn of the helical spring and against which the spring seats, and a bearing which is active between the vehicle body and the upper spring seating and which permits the spring to rotate about its axis relative to the vehicle body when the steerable vehicle wheel is turned.

In the case of wheel suspensions of this kind, so-called MacPherson suspensions, the upper spring seating will normally comprise a dished or cupped element which is pressed from metal sheet and against which the upper turn of the spring supports through the intermediary of an annular damping element made of a resilient material. This damping element is intended to dampen low frequency vib¬ rations transmitted from the wheels to the body of the vehicle, via the spring. One such known wheel suspension is disclosed, for instance, in SE Patent No. 441 999. A damper arranged in this manner should be soft if it is to dampen vibrations effectively, but since it is subjected to relatively large forces it may not be so soft as to be deformed significantly by movement of the spring, since this would result in extensive total damper movemet and a restricted useful life span of the damper. Although a damper which is only slightly resilient will have a longer useful life span and result in shorter total damper move¬ ment, such a damper will be less effective in absorbing sound and vibrations.

The object of the present invention is to provide an arrangement of the aforesaid kind which has an upper spring seating that combines good vibration and acoustic damping abilities with a satisfactory life span and which can be produced more simply and more cheaply than a etal- -plate dished element provided with a rubber element.

This object is achieved in accordance with the invention by configuring the support surface of the spring seating from a plurality of surface parts formed on tongues or shoulders and distributed sequentially in the winding direction of the spring.

The shoulders or tongues are conveniently formed directly on an annulus or ring which serves as a seating for the bearing. The annulus bearing the shoulders or tongues may be made, for instance, of a polyurethane plastics mateial which is sufficiently hard to function as a bearing hold¬ er, the width of the shoulders or tongues, the number thereof and the spacing therebetween being adapted so that the pressure thereon will be as heavy as that required to provide the desired suspension. Because the total contact surface area is reduced in this way in relation to the contact surface area of a homogenous ring, the increased hardness of the damper will be compensated for by a small- er total area through which sound can propagate from the wheels to the vehicle body, therewith resulting in good sound damping. A plastic annulus or ring of this kind provided with shoulders or tongues in the aforesaid manner is cheaper to produce and lighter in weight than hitherto known spring seatings which comprise a sheet-metal dished element and a rubber damping ring. The invention will now be described in more detail with reference to exemplifying embodiments thereof illustrated in the accompanying drawing, in which

Figure 1 is a longitudinal sectional view of an arrange¬ ment for mounting and journalling a MacPherson-type spring seating in a vehicle wheel housing;

Figure 2 is a schematic view from beneath the upper spring seating in Figure 1; and Figure 3 is a view III-III in Figure 1.

In Figure 1 the reference 1 identifies an upper plate which forms part of a front wheel housing of an automotive vehicle and on which the upper end of a MacPherson-type spring strut is mounted and joumalled. Since wheel sus- pensions of this kind are well known, only those parts of the suspension required for the actual mounting arrange¬ ment 2 will be described. Those desiring a more detailed description of the spring strut itself are referred,, for instance, to the aforementioned Swedish Patent Specifi- cation No. 491 999.

The illustrated mounting arrangement 2 includes two dished or cup-shaped elements which are pressed from sheet metal and welded one to the other and which are attached by means of two screws, of which one is shown at 5, opposite an opening 6 located in an outwardly flanged part 7 of the wheel housing 1. The dished elements 3, 4 have a central opening 8 which lies in register with the opening 6, and a piston rod 9 forming part of the shock absorber incorpor- ated in the spring strut extends through both of said openings. The upper end of the piston rod 9 extends into a rigid, toothed plate 10 and is screwed firmly to the plate by means of a nut 11 located in the opening 6. The dished element 3 has welded thereon a steel ring or annulus 12 to which the plate 10 is connected with the aid of a rubber element 13, which is welded firmly to the plate 10 and the annulus 12 and includes spoke-like parts 14, which extend between the plate 10 and the annulus, and damping cushions or pads 15, 16 on its top and bottom surfaces respect¬ ively. The described arrangement provides a resilient piston-rod mounting assembly having dampened, limited deflection when the cushions 15, 16 strike against the lower dished element 3 and the outwardly flanged part 7 of the wheel housing respectively.

Mounted on the undersurface of the dished element 4, e.g. as by adhesive bonding, is a plastic ring or annulus 17 which serves as a seating for the upper bearing race of a thrust bearing 18. A_. lower plastic ring or annulus 19 forms a seating for the lower bearing race of the thrust bearing 18.

In accordance with the invention, the annulus 19 is configured as a seating for the upper turn of a helical spring 20 which surrounds the shock absorber of the spring strut. To this end, tongues 21 project downwardly from the bottom surface of the annulus against which the spring is seated. The tongues 21 have end surfaces which conform with the cross-sectional profile of the spring rod or wire from which the spring is made and which form support sur- faces for the upper turn of the spring. As will be seen from Figure 2, tongues 21 are arranged which abut the upper turn of the spring around approximately three- -quarters of said turn, wherein the tongues over the last half of said turn are spaced apart at a distance a_ which is shorter than the distance Jb, or tongue spacing, at the beginning of the turn. The reference c. in Figure 2 iden¬ tifies the centre line of the spring rod.

When the spring is at rest, i.e. is only subjected to the static load of the weight of the vehicle, it is preferred that only a part of the last spring turn will support against the tongues 21, so that the tongues 21 having the mutual spacing b_ will not come into successive contact with the spring until the spring is compressed. This will afford improved acoustic and vibration damping, not only because the tongues are deformed elastically by the pressure exerted by the spring, but also because the sound transmitting contact surface has an optimum, small area.

As will be seen from Figure 1, the annulus 19 and the tongues 21 are formed integrally with one another, and may be made from a polyurethane plastic material. The annulus 19 is also configured with side walls 24, 25, of which the wall 24 has a groove or channel 26 which receives a seal¬ ing lip 27 formed on the upper ring 17.

The outer end of the other wall 25 projects into a groove or channel 28 in the upper annulus 17. This arrangement provides a simple means for effectively sealing the bear¬ ing 18. In this way, functions such as a bearing holder function, bearing sealing function and spring seating function are combined in one single element, which can be moulded in one single piece from a plastic material.

It will be understood, however, that it lies within the concept of the invention to separate these functions and accordingly to produce the bearing holder and the spring seat incorporating said tongues as two mutually separate elements.

Claims

1. An arrangement for mounting and journalling a spring strut which is intended for a steerable vehicle wheel and which includes a shock absorber and a helical spring surrounding the the shock absorber and mounted in the vehicle body, said arrangement including means for resiliently mounting the upper end of the piston rod of said shock absorber in the vehicle body, an upper spring seating having a support surface which is adapted to conform to the upper turn of the helical spring and against which the spring seats, and a bearing which is active between the vehicle body and the spring seating and which permits the spring to rotate relative to the vehicle body when the steerable vehicle wheel is turned, charac¬ terized in that the support surface of the spring seating (19) is configured from a plurality of surface parts (23) which are formed on shoulders or tongues (21) and which are arranged sequentially in the winding direction of the helical spring (20).

2. An arrangement according to Claim 1, characterized in that when the spring (20) is at rest a part of the upper turn of said spring is located at a distance from opposing surface parts (23) on the spring seating (19) such that the spring rod, seen from the outer end of said spring turn, will be brought successively into contact with said surface parts as the spring is compressed.

3. An arrangement according to Claim 1 or Claim 2, characterized in that the shoulders or tongues (21) are distributed such that the distance (b) therebetween is initially greater than the distance (a) therebetween at the end of the spring turn supported against the spring seating (19).

4. An arrangement according to any of Claims 1-3, charac¬ terized in that the shoulders or tongues (21) are formed integrally with an annulus (19) which serves as a seat for said thrust bearing (18).

5. An arrangement according to Claim 4, characterized in that the annulus (19) accommodates the bearing (18) in a channel having sides (24, 25) which in coaction with sides (27, 28) on a further annulus (17) located on the opposite side of the bearing form a labyrinth seal which prevents dirt from entering the bearing.