GB2056616A

GB2056616A - Support plate for a helical compression spring

Info

Publication number: GB2056616A
Application number: GB8022744A
Authority: GB
Original assignee: Hoesch Werke AG
Current assignee: Hoesch Werke AG
Priority date: 1979-08-10
Filing date: 1980-07-11
Publication date: 1981-03-18
Also published as: DE2932500A1; GB2056616B; FR2463327A1; JPS5635829A; FR2463327B3

Abstract

A helical compression spring (9) has each end thereof received on a support plate (1) having the form of a circular disc with an edge slot (4) to provide a seating surface (2) for the spring end which extends from the slot, around the periphery of one face of the disc and over the slot to have an arcuate extent exceeding 360 DEG . <IMAGE>

Description

SPECIFICATION Support plate for a helical compression spring Description The invention relates to a support plate for a helical compression spring.

Spring systems having a progressive characteristic curve have come into use in automobile construction because of increasing demands for vehicle safety and travelling comfort. The progressive loaddisplacement characteristic is achieved either by the use of linear characteristic helical compression springs combined with rubber or synthetic plastic springs, or else by using progressive helical compression springs, in which the effective number of turns is reduced during the course of spring movement.

For example in US-PS 176 174, a helical compression spring is described, wherein the turns come into mutual contact for achieving the progressive characteristic. This rolling action of the turns onto each other introduced a clattering noise problem and damaged the protective surface of the coils. The result of this was spring fracture due to the effect of corrosion.

In DE-AS 26 20 149, there is described the use of a resilient protective sleeve, which to a large extent removes the problems of clattering and corrosion for a certain time. The manufacture and assembly of the sleeves howeverentail substantial expense.

DE-GM 1660341 proposes the introduction between the spring coils of a rubber profiled member, which in the course of the spring displacement resiliently blocks a portion of the coils and establishes a progressive load-displacement characteristic. Nevertheless experience has shown that moisture accumulates in the area of permanent contact between the rubber and the steel spring and only dries out with difficulty. This circumstance is favourable to the setting up of corrosion, and greatly reduces the useful life of the spring.

DE-AS 20 00 472 describes a double frusto conical spring, also referred to as a barrel spring. The wire diameter and the diameter of the coils are nonuniform. The progressive nature of the loaddisplacement characteristic is achieved by a rolling action upon a plane support.

Features similar in principle are desribed in DE-AS 25 06 420 for wound non-cylindrical compression springs. These springs have the shape of a diabolo.

Depending on the dimensions and shape of the available space for installation, the springs possess structural advantages, of compensating forthe irregularities of the support surfaces of such springs.

For that purpose the region which is made with an incline amounts to at least 270 degrees and a maximum of 360 degrees.

The present invention provides a support plate for a helical compression spring having an inclined surface serving as a seating for the end of the spring, the seating surface extending over more than 360".

The invention makes it possible to satisfy spring requirements in respectof progressive loaddisplacement characteristic, freedom from clattering noise, resistance against corrosion, and small structural volume, particularly small structural height, and to achieve this in a simple manner and at relatively small capital cost, notwithstanding all other requirements.

According to the strength of the desired progression, the ends of a spring assembled with spring support plates embodying the invention may lie more or less "inactive", which means that the slope of the turns and of the spring plate are equal. There is optimal utilization of the material when only about 0.5 turns per end of the spring lie "inactive" at the beginning of the spring movement under load, and as the application of load increases the proportion of the turns lying upon the spring plate also increases in accordance with the requires spring progression.

The greater the diameter of the turns selected for a helical compression spring, the smaller is the number of turns required. The total number of turns should not, however, fall substantially below 3.5.

A substantial advantage of the invention resides in the fact that it permits use of helical compression springs which are simple to manufacture and are therefore cost effective. The helical compression springs can be produced with a uniform or nonuniform wire diameter or turns diameter. In addition, should it be necessary to provide a reduced spacing between some of the first active turns of the spring, for example to give a load-displacement characteristic having an intensified progression in a particular region, this is possible in manufacture without increased expense.

By selecting a large turns diameter and a small number of turns it is possible to keep the required structural height relatively small.

Simple helical compression springs having a constant turns diameter can be employed with special advantage, but in some cases the use of springs with a non-uniform turns diameter may also be advantageous.

A spring support plate embodying the invention may consist of metal - in a solid form or in a form produced by the combination of pressing and welding - and the seating surface may be provided with an elastic cladding, for example of rubber or synthetic plastic material, or some other noise-reducing material, whereby the tendency to clattering noises is counteracted and a certain damping effect is achieved. In this situation it is also advantageous to arrange that only a small portion of the turns take part in the rolling action.

The seating surface may however be provided with a metallic protective cladding which functions, for example, as a cathode with respect to the helical compression spring, examples of which cladding may be zinc or some other corrosion-inhibiting material. By the provision of such a cathodic protective cladding, for example a coating of zinc, a tendency to rusting of the helical springs is counteracted in the rolling action region where the surface protection of the helical springs is subject to damage.

However it is also possible to make the spring plate entirely of rubber, or synthetic plastics material, or some other noise and corrosion reducing material.

The invention is further described below, by way of example, with reference to the accompanying drawings, in which: Figure 7 is a front view of a spring support plate embodying the invention; Figure 2 is a plan view of the plate of Figure 1; Figure 3 is a front view of the ends of an assembly comprising a helical compression spring and two of the plates of Figures 1 and 2, at the beginning of the progression; Figure 4 is a like view of the end of the progression; and Figure 5 is a spring rate diagram in which the loading of the spring is plotted against its length through the positions shown in Figures 3 and 4.

The spring support plate 1 shown in Figures 1 and 2 has the general form of a circular disc, and has at its periphery on one side a seating surface 2 proceeding in a rising incline. The surface 2 starts from the inner end 3 of a slot4formed in the turned surface of the plate, and extends to the diametrally opposite region 5. From the region 5, the surface 2 continues through a further 180 beyond a position 6 overlying the slot end 3 by an arcuate length 7 to a position 8 above the open end of the slot. Accordingly, the seating surface 2 extends through an angle exceeding 360" by the arcuate length 7.

Figures 3 and 4 show the ends of a helical compression spring 9 received between a lower support plate 1 and a like upper support plate. In order to simplify the description, only the conditions existing at the lower spring plate are described below, with reference to Figure 5.

When the helical compression spring 9 is in the unloaded condition (LO in Figure 5), the spring plate 1 is rotated about its axis, with the slot 4 receiving the associates spring end portion 10, until the latter abuts against the inner end 3 of the slot. The spring end portion 10 is therefore now positioned upon the seating surface 2 of the spring plate from the slot end 3 to the region 5, short of this region.

Upon stressing ofthe spring 9 up to a spring load F1, the spring rate (starting rate) is almost constant.

This condition of the spring, in which the spring end portion 10 is seated on the surface 2 from the slot end 3 to the region 5 is shown in Figure 3.

After the spring load F1 has been exceeded, the helical compression spring 9 rolls down to engage the seating surface 2 beyond the region 5 and then beyond the position 6 and the underlying slot end 3, to achieve 360" seating, and then on to the seating surface end position 8. In this action, the progression of the spring characteristic marked by reference numeral 11 on Figure 5 follows on from the position 5. When a spring load F2 is reached, corresponding to the situation shown in Figure 4, spring end portion 10 is seated upon the spring plate 1 up to the position 8, that is to say starting from the free'end of the spring end portion 10, the spring is seated upon the surface 2 over 360" plus the arcuate dimension 7.

When the loading is further increased beyond load F2 no further seating of any additional part of the turns of the spring 9 takes place, and the spring rate (end rate) of the spring remains almost linear.

Claims

1. Asupportplatefora helical compression spring having an inclined surface serving as a seating for the end of the spring, the seating surface extending over more than 360".

2. A support plate as claimed in claim 1 having the form of a disc with a slot in the edge surface thereof, the seating surface extending from within the slot, around the periphery of a face of the disc and over the slot.

3. A support plate as claimed in claim 1 or 2 consisting of metal, the seating surface carrying an elastic cladding.

4. Asupport plate as claimed in claim 1 or 2 consisting of metal and provided with a metallic protective cladding.

5. A support plate as claimed in claim 1 or 2 consisting entirely of rubber or synthetic plastics material.

6. A support plate substantially as herein described with reference to Figures 1 and 2 of the accompanying drawings.

7. A spring assembly comprising a helical compression spring housing each end thereof seated in a support plate as claimed in any preceding claim.

8. A spring assembly substantially as herein described with reference to Figures 3 and 4 of the accompanying drawings.