GB2162802A - Plastics wheel - Google Patents

Abstract

Fibre reinforced synthetic resin wheels at economic cost for motor vehicles have encountered problems due to creep arising from high temperature cycling in use, causing relaxation of the wheel fastenings. Two-piece fibre reinforced synthetic resin wheel 1 has a wheel fixing portion 3 of low heat conductivity and high temperature distortion resistance which has different material properties to a wheel portion 2 to which it is bonded. Portion 3 may be mechanically keyed to portion 2 to facilitate transmission of torque and/or receive support against bending loads. Wheel fixing nuts preferably engage load bearing inserts 7 through which wheel mounting studs pass to secure the wheel to a brake assembly. Torque on the wheel nuts maintains a safe level due to the properties of wheel fixing portion 3, whilst wheel portion 2 is protected from excess temperatures by the heat barrier provided by wheel fixing portion 3. <IMAGE>

Description

SPECIFICATION Plastics wheel This invention relates to a wheel of reinforced plastics material intended to be used adjacent a heat generating source, for example a vehicle wheel which is mounted adjacent a brake.

Various synthetic resin materials have been developed for such wheels to meet the necessary strength and fatigue requirements, including both thermoset and thermoplastic materials. Many of these materials are unable to withstand heat cycling, as during braking, without creep. However there are other materials, for example a -polyimide or a phenolic resin, which are better able to withstand the heat cycling which occurs during braking and without creep. Creep is a significant problem which has been identified as the cause of relaxation of fastening torque applied to fixing devices, for example nuts or bolts, for plastics wheels.

These latter materials are significantly more expensive and production costs for wheels of such materials are also greater.

One solution which has been proposed (British patent no. 2069422) seeks to reduce the heat transfer from the brake to a fibre reinforced synthetic resin wheel by the interposition between wheel and hub of a steel ring having a small contact area with the heat source whereby heat transfer is reduced. The ring thus provides a heat sink which is in intimate contact with the wheel. Air passages are provided between the ring and the heat source for a cooling air flow which can be generated during rotation of the wheel. Heat transfer from the wheel studs to the wheel is reduced by utilising special wheel nuts and bearing plates to define insulating air pockets.

According to the present invention a wheel made primarily of reinforced plastics material comprises in combination a wheel portion and a wheel fixing portion having holes to receive wheel fixing portion having holes to receive wheel fixing studs bolts or like fixing members wherein the wheel fixing portion is secured to or integral with the wheel portion, the wheel fixing portion being of a material having low heat conductivity and high temperature distortion resistance, thereby providing a secure fixing for the wheel and a barrier to conduction of heat from an adjacent heat generating source to the wheel portion when in use.

The wheel fixing portion may be bonded, for example adhesively bonded or chemically bonded to the wheel portion.

The wheel fixing portion may be mechanically keyed to the wheel portion. The mechanical key may be such as will enable torque to be transmitted between the wheel fixing portion and the wheel portion. The mechanical key may be such that the wheel portion reinforces the wheel fixing portion to resist bending loads.

Preferably the wheel fixing portion incorporates load bearing inserts against which fixing devices are adapted to bear to secure the wheel for use.

These inserts protect the holes in the wheel from wear during fitting and removal.

The invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a front elevation of a wheel, only half of which is shown, the other half being similar, Figure 2 is a rear elevation of the wheel half of Figure 1, Figure 3 is a section on line A-A of Figure 1, Figures 4, 5 and 6 are scrap sections as on line A-A of Figure 1 illustrating alternative constructions, Figure 7 is a scrap view of a rear elevation, as of the wheel of Figues 1 to 3, illustrating a further alternative construction, and Figure 8 is a section through the wheel on line B-B of Figure 7.

Referring to the drawings Figures 1 to 3 a composite fibre reinforced plastics wheel 1 for a motor vehicle has a wheel part 2 and a wheel fixing part 3 which are bonded together. In this example the wheel part 2 is of glass fibre reinforced vinyl ester and has a conventional rim portion 4 with a type fitting well 5. The wheel shown has four holes 6 to receive wheel fixing nuts (not shown) for securing the wheel to studs on a wheel hub or brake drum.

The wheel fixing part 3 in this example is a glass fibre reinforce polyimide moulding containing four metallic sleeve inserts 7 (not shown in Figure 1 for clarity) of a size to receive the wheel fixing studs and to provide a bearing area on to which the wheel fixing nuts are clamps to secure the wheel in use. As shown, the inserts 7 are cylindrical with two axially spaced shoulders 8 and 9, of which shoulder 8 provides a nut bearing area. The shoulders serve to key the inserts in the polyimide moulding. The clamping load is transmitted by the inserts 7 to the polyimide moulding, which also accepts part of the clamping load direct from the nuts.

Preferably the wheel fixing part 3 is made, for example as an injection or compression moulding,.

with the inserts 7 in situ. This is then placed and located in a mould for the wheel. During injection of the vinyl ester the wheel fixing part 3 becomes bonded to the wheel part 2.

Referring now to Figure 4, the wheel fixing part 3 is of smaller external diameter at the interface with the wheel portion 2 and also has an annular groove 11. This construction enables the wheel part 2 to be keyed to the wheel fixing part 3 so as to reinforce the bond and enable a proportion of the bending loads to be borne by the wheel part at 12 where it surrounds the wheel fixing part 3.

The constructions shown in Figures 5 and 6 are variations on the construction of Figure 4, showing alternative ways in which the wheel part 2 can be keyed to the wheel fixing part 3. Manufacture may be the same as for the wheel of Figures 1 to 3 except that the recesses 13, 14 for the key would be machined as moulding is not practicable.

Referring now to Figures 7 and 8, the wheel fixing part 3 (shown partly in broker lines in Figure 7) has a generally cross-shaped portion 15 which mates with a correspondingly shaped recess in the wheel part 2.. As with the previously described constructions the wheel fixing part 3 is made as a separate assembly with the inserts 7, as by moulding.

It is then placed and located in the mould for the wheel and abond is formed during moulding of the wheel. This keyed construction enables torque to be transmitted through the material of the wheel and wheel fixing parts rather than merely through the bond, as well as enabling the wheel part 2 surrounding the wheel fixing part 3 to bear bending loads.

As shown in Figure 8 the interfaces between the wheel part 2 and wheel fixing part 3 are in directions respectively parallel and normal to the wheelaxis (of rotation), The keying may be further enhanced to give a dovetail type joint by appropriately inclining those joint lines (or some of them) which are shown as being parallel to the wheel axis.

It will have been observed that in the exemplary constructions which have been described the wheel fixing part 3 is interposed between a brake drum or hub and the wheel part when in use so as to provide a barrier to heat transference from, for example, the vehicle brake. An air gap is provided between the wheel fixing device and the holes 6, so preventing direct heat transfer from the fixing devices to the wheel part 2. Preferably the wheel part and wheel fixing part are keyed together as well as being bonded together. It will be appreciated that the constructions of Figure 3 and 8 are such that bonding of the wheel part and wheel fixing part can be effected, for example with a suitable adhesive, after the two parts have been made separately.

It will be appreciated that other constructions can be devised to provide a key between the wheel part and wheel fixing part and are not excluded from the scope of this invention.

Claims (9)

1. A wheel made primarily of reinforced plastics material comprising, in combination, a wheel portion and a wheel fixing portion having holes to receive wheel fixing studs bolts or like fixing members wherein the wheel fixing portion is secured to or integral with the wheel portion, the wheel fixing portion being of a material having low heat conductivity and high temperature distortion resistance, thereby providing a secure fixing for the wheel and a barrier to conduction of heat from an adjacent heat generating source to the wheel portion when in use.

2. A wheel as claimed in Claim 1 wherein the wheel fixing portion is bonded to the wheel portion.

3. A wheel as claimed in Claim 1 or Claim 2 wherein the wheel fixing portion is mechanically keyed to the wheel portion.

4. A wheel as claimed in Claim 3 wherein the mechanical key is such as will enable torque to be transmitted between the wheel fixing portion and the wheel portion.

5. A wheel as claimed in Claim 3 or Claim 4 wherein the mechanical key is such that the wheel portion reinforces the wheel fixing portion to resist bending loads.

6. A wheel as claimed in any one of the preceding claims wherein the wheel fixing portion incorporates load bearing inserts in the holes against which wheel fixing devices are adapted to bear to secure the wheel for use.

7. A wheel as claimed in any one of the preceding claims wherein the wheel fixing portion is a polyimide resin moulding

8. A wheel as claimed in any one of Claims 1 to 6 wherein the wheel fixing portion is a phenolic resin moulding.

9. A wheel substantially as described herein with reference to Figures 1 to 3,.Figures 4, 5 or 6 or Figures 7 and 8 of the accompanying drawings.