GB2069422A

GB2069422A - Mounting synthetic resin wheels on hubs

Info

Publication number: GB2069422A
Application number: GB8041061A
Authority: GB
Original assignee: Dunlop France SA
Current assignee: Dunlop France SA
Priority date: 1979-12-28
Filing date: 1980-12-22
Publication date: 1981-08-26
Also published as: GB2069422B; DE3047837A1; IT1150098B; IT8026974A0

Abstract

A one-piece wheel (1) made from glass-fibre reinforced synthetic resin is mounted on a hub (2) with a ring (3) and specially formed nuts (13) being provided to prevent excessive heating of the wheel by the hub (2). In Fig. 3 the ring (3) has ribs contacting the hub to leave passages through which cooling air is drawn by fan blades (10). Alternatively the ring may have protrusions which contact the hub and define air pockets between the ring and wheel. Each nut (13) carries a bearing plate (23) which prevents the inner end (18) of the nut contacting the base of a recess (19) in the wheel, and the associated hub stud (11) passes through an aperture of larger diameter in the wheel, so that insulating air pockets are formed. The plate (23) may have notches (25) or be curved as shown, and the nut bore may be enlarged at (20), to define insulating air pocket(s). Thermally insulating material may be provided between the plate (23) and the nut or the wheel. <IMAGE>

Description

SPECIFICATION One-piece wheel and mounting nut therefor The present invention relates to a wheel made in one piece from synthetic resin reinforced with fibres, more especially glass fibres, and nuts for locking such a wheel onto a hub.

It is known that in the automobile industry the present tendency consists, in order tb save energy, in reducing, as far as can be done, the weight of the vehicle more especially by substituting components made from synthetic resin for the metal components.

Wheels made from synthetic resin reinforced by glass fibres are already known. One such wheel is described, for example, in French Patent Specification No. 77 12027 dated 12 April 1977.

The major problem encountered in the use of these wheels is conservation of integrity and mechanical strength throughout the temperature range that can exist at the hub of the wheel, that is to say a range which extends approximately from -400C to +2000C. The temperature of -400C is reached in certain northern regions while the temperature of +2000C may result from excessive braking.

At present there do not exist on the market resins which preserve the necessary characteristics throughout the temperature range, the only resins which nearly meet this requirement being very expensive, and difficult and expensive to use.

An object of the present invention is to ensure that, even if it is inevitable that the aforesaid temperature will be reached at the hub of the wheel the disc portion of the wheel should be protected from thermal stresses caused by wide temperature fluctuations.

In accordance with one aspect of the present invention there is provided a wheel made in one piece from fibre-reinforced synthetic resin comprising a rim, intended to receive a pneumatic tyre, and a disc, intended to be mounted on a hub by mounting means, comprising nuts engaging threaded studs on the hub, the latter passing through respective holes in the disc each of a diameter greater than that of the associated stud, wherein there is interposed between the disc and hub a thermal insulation ring having at least one flat surface in abutment with the hub, and made of a material such that there are ensured a good mechanical contact and a heat shield between the wheel and the hub designed to obviate excessive heating of the wheel by conductivity from the hub.

Although synthetic resins, such as polyester, do not maintain, contrary to certain epoxy resins formerly used, good characteristics of mechanical strength over the temperature range extending from -400C to +2000 C, which is encountered at the hubs of wheels of motor vehicles, these resins are however usable for the production of wheels for vehicles in accordance with the invention, not having to withstand such temperatures, as a result of the poor heat exchange between the hub and the wheel disc, the heat shield provided between them having the effect that all the heat applied to the hub by the associated brake is not transmitted to the wheel disc, while the connection between the hub and the wheel disc remains mechanically effective.

In accordance with the invention, this component, ensuring the mechanical contact and the thermal insulation of the wheel disc relative to the hub, may be made of steel, or of a material having suitable mechanical and thermal properties, taking into account the result sought after, integral with the inboard face of the wheel disc, a surface in contact with the hub being provided either by the inboard surface of the thermal insulation ring or by a plurality of uneven areas or protrusions on the ring which take the form of circular protrusions or radial ridges, these embodiments leaving, between the wheel disc and the hub, cavities filled with air, providing thermal insulation, so that the transmission of heat between hub and wheel disc by conductivity is improved.

In order to promote the cooling of the hub and of the brake arranged on the inboard side of the wheel disc, it is advantageous for this latter to have a central aperture, allowing the passage of air, and for a plurality of fins to extend over the inboard face of the wheel disc, between this central aperture and the zone of the wheel disc where the thermal insulating ring is provided, and preferably in the same radial planes as the protrusions of the latter.

By the present invention the intention has also been to improve the results obtained in this way, by also preventing any heating which might occur through the medium of the means for mounting the wheel on the hub, in particular the studs and nuts used for this purpose.

Another aspect of the present invention is therefore characterised in that it comprises, in addition, a second heat shield, preventing excessive heating of the wheel from the hub, through the mounting means, this second heat shield comprising the following features, alone or in combination: a) a thermally insulating air cavity, defined by a recessing of the central bore of the nut at its end nearer the wheel disc.

b) an annular thermally insulating air chamber defined between the stud and the periphery of the corresponding hole in the wheel disc, when the nut is screwed onto its stud, by the centering of the end portion of the nut nearer the wheel disc in a recess provided in the outboard face of the wheel disc, so that the stud passes through the hole without coming into contact with the wheel disc.

c) a thermal insulator placed between the nut and the wheel disc.

In a preferred embodiment, in which each nut for mounting the wheel on the hub is associated with a flange or small bearing plate on the wheel, freely rotatable relative to the nut, the second heat shield can also comprise, in addition, the following features, taken also either alone or in combination: d) another thermally insulating annular air chamber, defined between the end of the nut nearer the wheel disc and the latter, by the bearing plate or flange, the shape, dimensions and arrangement of which prevent any contact between the wheel and the nut when screwed onto the corresponding stud.

e) a thermal insulator between the nut and its bearing plate or collar.

f) a thermal insulator between the surface of the flange or plate in contact with the wheel and this latter, this insulator being for example moulded onto the flange or plate.

g) thermally insulating air cavities, defined by notches formed in the bearing plate or flange associated with each nut.

h) a further air pocket, defined by the wheel disc, the nut and the bearing plate through the latter having the shape of a bell, and the elastic deformation of which, when the nut is screwed onto the stud ensuring that the nut is stressed to prevent loosening of the nut under the effect of vibration.

The present invention also has as its object the nuts for mounting a wheel, such as defined above, onto a hub, and the structure of which has that or those of the features set forth above which relate thereto, taken individually or in combination.

Preferred embodiments of the present invention will now be described with reference to the accompanying drawings, in which: Figures 1 and 2 are cross-sectional views in radial planes, Figure 2 being a partially perspective view, of a wheel in accordance with the invention; Figures 3 and 4 are similar views of a second embodiment of a wheel including an aerodynamic cooling system; Figure 5 is a partial view, in radial section, of a wheel fixed to a hub by nuts having supporting flanges the stud mounting holes in the wheel being enlarged; Figure 6 is a plan view of the nut and of the flange shown in Figure 5, showing their position relative to the centre of the wheel; Figure 7 is a side view of a nut having a flange similar to the one shown in Figure 5, sectioned at the level of the flange; Figures 8 to 10 are sectional views of modified nuts;; Figure 11 is a top view of a bell-shaped notched plate, to be crimped onto a mounting nut; Figure 12 is a radial sectional view of the bearing plate in accordance with Figure 11, associated with a nut for mounting a wheel on a hub, with an enlarged hole around the stud, and Figure 13 is a sectional view of a nut having neither a flange nor a bearing plate.

In Figure 1 there can be seen a part of the disc 1 of a wheel made of synthetic resin, for example made of poiyester, reinforced with glass fibres, which is fixed onto a hub 2 of a motor vehicle, with a thermal insulation ring 3 placed in between, integral with the inboard side of the wheel disc 1, and made of a material such as steel, chosen so that there are simultaneously ensured between the wheel disc 1 and the hub 2 a good mechanical contact and a heat shield preventing any excessive direct heating of the wheel by the hub 2.

The ring 3, integral with the inboard face 4 of the disc 1, bears a plurality of protrusions, preferably made by deforming the rim 3 in a stamping operation. The stamping of the studs 5 is a satisfactory solution, to the extent that it uses a technique conventional in the wheel industry.

Moreover, this stamping leaves, between the disc 1 and the ring 3, a cavity within each protrusion 5 and a space between the undeformed part of the rim and the hub filled with air which is thermally insulating so that the transmission of heat, between the hub 2 and the disc 1 is primarily by radiation, and is by conduction only at the points of contact of the protrusions 5 with the hub 2.

The protrusions 5 obtained by stamping have flat free end surfaces ensuring a satisfactory contact between the hub 2 and the disc 1. Of course, the central hole 7 with which the disc 1 is provided plays an essential part in the cooling of the disc and it must not be obturated.

The previously mentioned components are to be found in part in Figure 2, in which there can be seen the disc 1, the thermal insulation ring 3, the protrusions 5, the holes 6 allowing passage of the wheel-mounting studs carried by the hub, as well as the central ventilation hole 7 allowing the passage of external air to the rear of the disc 1 with a view to cooling both this latter and the hub 2.

The embodiment shown in Figures 3 and 4 differs from the preceding one in that it entails an aerodynamic action of the wheel itself in the course of its rotation, which aerodynamic action takes the form of a forced centrifugal ventilation.

To this end, on the ring 3, the previous support protrusions 5 have been replaced by radial bars 9 which are preferably made by stamping for the reasons set forth previously with regard to the protrusion 5. As in the first embodiment, the surface of contact between the hub 2 and the disc 3 is reduced to the sum of the inboard surfaces of the bars 9 which ensure an adequate anti-friction mechanical connection. The surface of a bar 9 in contact either with the hub or the disc is of the order of 100 mm2, which, for eight bars 9, gives a total contact area of 800 mm2. The spaces comprised between the bars 9 provide passages for the circulation of cooling air. In accordance with another feature of the invention, there are provided, inside the disc 1, a plurality of fins 10 intended to direct the external air drawn in through the central aperture 7 towards the spaces between the bars 9 so that this air cools the members which are disposed behind the disc 1.

Preferably the fins 10 are arranged in alignment with the bars 9, i.e. in the same radial planes as these latter. In Figure 3, the direction of circulation of air is illustrated by the arrows F. Thus, the faster the wheel turns the greater is the air pressure and the faster is the displacement of air, which makes it possible to obtain increased cooling. The height (axially of the disc) both of the protrusions 5 and the bars 9 is of the order of 2 to 3 mm, which allows a good circulation of the air.

In the example shown in Figure 5, the thermal insulation ring 3 does not have any surface protrusions in contact with the hub 2, but is in contact with the latter throughout its entire inboard surface. The ring 3 is perforated with holes 6', evenly distributed over its circumference, in a number at least equal to the number of holes 6 provided in the wheel disc 1, and in register with these latter. The holes 6 having a significantly greater diameter than the outside diameter of the threaded wheel mounting studs 11 carried by the hub 2, and intended to pass through holes 6 and 6', when the wheel is positioned to be fixed onto the hub 2 by screwing flanged nuts 12 onto the threaded studs 11.

Each flanged nut 12 comprises a nut 13, onto which is crimped a supporting flange 14, having, as can clearly be seen in Figure 6, a shape in plan which is substantially that of a portion of an annulus. The radially inner corners of the flange 1 4, that is to say those nearer the centre of the annulus which corresponds to the centre of the wheel, when the flange is suitably arranged on the wheel, are cut to have concave recesses 15, and the external edge 1 5 of each recess is thinned down to a rounded profile, as appears on the section of the flange 14 visible in Figure 5.The flange 14 is retained on the nut 13, in a groove defined between an outer radial shoulder 1 7 on the middle part of the nut 13, and a shoulder formed by a radial projection 1 8 at the end of the nut 13 nearer the hub 2, when the nut 13 is threaded onto the stud 11. On the other hand, the flange 14 is free to rotate on the nut 1 3. By cooperation with a recess 1 9 formed in the outboard face of the wheel disc 1, and into which a stud hole 6 opens coaxially the end 1 8 of the nut 13, which has with the recess 1 9 a clearance less than that between the stud 11 and the hole 6, ensures the centering of the nut 13 relative to the associated hole 6 in the wheel disc 1, so that when the nut 1 3 is fully threaded onto the stud 11, this latter passes through the hole 6 without contact with the wheel disc 1, which is applied with a peripheral crown 3 against the hub 2 supported by the flanges 14, the shape, dimensions and arrangement of which prevent any contact between the inner end of each nut 1 3 and the bottom of the associated recess 1 9.

There are thus formed two thermally insulating annular air spaces, between each stud 11 and the wheel disc 1, and between the nut 1 3 and the bottom of the recess 19, which constitute a second heat shield, added to a first one formed by the crown 3, to limit the heating of the wheel disc by the hub 2.

The flanged nut 12, shown in Figure 7, is similar to the one previously described with reference to Figure 5, from which it differs only by the thickness of the flange 1 4.

The flanged nut in accordance with Figure 8, of a thickness less than that of the two nuts 1 3 previously described, also has a shoulder 1 7 and a radial end projection 1 8 to retain the flange 14 on the nut 1 3. However, in addition, a recess 20 is machined in the end portion of the bore of the nut 1 3 nearer the hub 2, in a position to define around a portion of the stud 11 an annular thermally insulating cavity filled with air, which is added to the two annular air chambers, obtained as explained with reference to Figure 5, in order to strengthen the second heat shield.

The flanged nut in accordance with Figure 9 is similar to thosa described with reference to Figures 5 and 7, from which it differs only by the presence of a washer 21, made of a thermally insulating material, placed between the shoulder 17 of the nut 13 and the flange 14, in order to strengthen, in this case too, the second heat shield between the hub 2 and the wheel disc 1.

The flanged nut in accordance with Figure 10 corresponds to the one shown in Figure 9, with the difference that the thermally insulating material is not placed between the shoulder 1 7 of the nut 13 and the flange 14, but is moulded onto the internal or supporting face of the flange 14, to form an insulating sheath 22 which, when the nut 13 is fully threaded onto the stud 11, is positioned between the bearing surface of the flange 14 and the wheel disc 1.

The small plate 23, a plan view of which is shown in Figure 11, and which has a shape similar to that of the flange 14 (annular sector, the radially inner corners of which are recessed), has a circular aperture 24, into which diametrically opposite pairs of notches 25 open. Each notch is substantially square in plan. Between the cruciform aperture thus defined and the external edge 26 of the small plate 23, which is thinned to have a rounded profile, the small plate 23 is curved at 27, so as to assume a bell shape which can be seen in Figure 12.This small plate 23, notched and bell-shaped, is used as a bearing plate after crimping onto a nut 13, on which it is mounted so as to rotate freely, but is restrained from axial displacement by the four sectors 28, defined between the notches 25 which engage between the shoulder 1 7 of the nut 13 and the small plate 23. The radial projection 18 of the nut 13, of an axial dimension corresponding to the height of the curved portion 27 of the small plate 23, ensures, as explained with reference to Figure 5, the centering of the nut 13 in a recess 19 of the wheel disc 1, so that the stud 11 passes through the wheel disc 1 without coming into contact with it. In addition, a recess 20 is machined in the end portion of the bore in the nut 13 nearer the hub 2, and, finally, a thermal insulator (not shown) may be provided, for example by moulding, between the inboard face of the small plate 23 and the wheel disc 1.

The shape, dimensions and arrangement of the small plate 23 prevent any contact between the end face of the nut 13 and the bottom of the recess 19, when the nut 1 3 is fully screwed onto the stud 11.

Thus a second heat shield is obtained, defined not only by the two annular air chambers, between the stud 11 and the wheel disc 1 and between the nut 13 and the bottom of the recess 19, by the air cavity of the bore 20, and, possibly, by the thermal insulator moulded onto that portion of the inboard surface of the small plate 23 which comes into contact with the wheel disc 1, but also by the air cavities defined by the notches 25, formed in the small plate 23, and by the supplementary air pocket defined within the small plate 23, thanks to its curved portion 27 between the plate 23, the wheel disc 1 and the nut 13.

At the same time, the elastic deformation of the small plate 23, when the nut 13 is tightened on the stud 11, stresses the nut 13 relative to the hub 2, which prevents loosening of the nut 1 3 under the effect of vibration.

The mounting of the wheel disc 1 and of the crown 3 on the hub 2 is not necessarily effected by nuts having a bearing plate such as 14 or 23 and nuts 13, such as the one shown in Figure 13, may be used instead. Such a nut comprises a recess 20, machined in its central bore, an end projection 1 8a for centering in a recess of the wheel disc, and a lining 28 of a thermally insulating material, integral with the end of the nut 1 3 which is against the wheel disc 1. Such a washer 28 may, for example be very easily made in the form of a steel washer pressed so as to assume a saucer shape in cross-section.

In addition, the length of the end projection 18 is such that it does not come into contact with the bottom of the recess in the wheel disc, when the nut 13 is fully threaded onto the stud 11 and fastens the wheel disc and the crown 3 against the hub 2.

Claims

1. A wheel made in one piece from fibrereinforced synthetic resin comprising a rim, intended to receive a pneumatic tyre, and a disc, intended to be mounted on a hub by mounting means, comprising nuts engaging threaded studs on the hub, the latter passing through respective holes in the disc each of a diameter greater than that of the associated stud, wherein there is interposed between the disc and hub a thermal insulation ring having at least one flat surface in abutment with the hub, and made of a material such that there are ensured a good mechanical contact and a heat shield between the wheel and the hub designed to obviate excessive heating of the wheel by conductivity from the hub.

2. A wheel made in one piece in accordance with claim 1 , wherein the said flat surface is provided by the inboard ends of protrusions or ribs on the inboard side of the ring.

3. A wheel made in one piece in accordance with claim 2, wherein the protrusions are hollow and of circular cross-section.

4. A wheel made in one piece in accordance with claim 2, and comprising a plurality of radial ribs formed on the ring.

5. A wheel made in one piece in accordance with any one of claims 2 to 4 wherein the disc has a central aperture for the passage of air.

6. A wheel made in one piece in accordance with claim 5, wherein a plurality of fins extend from the inboard side of the disc between its central aperture and the zone of the disc where the ring is situated.

7. A wheel made in one piece in accordance with claim 6, wherein the fins are in the same radial planes as the protrusions or ribs.

8. A wheel made in one piece in accordance with any one of the preceding claims 1 to 7, characterised in that it comprises a second heat shield to prevent excessive heating of the wheel by the hub incorporated in the mounting means.

9. A wheel in accordance with claim 8, wherein the second heat shield comprises a thermally insulating air cavity defined by an enlargement of the bore of the nut at the end portion thereof nearer the wheel disc.

10. A wheel in accordance with claim 8 or claim 9, wherein the second heat shield comprises a thermally insulating annular air chamber defined between each stud and the periphery of the corresponding hole in the wheel disc, when the associated nut is screwed onto said stud by centering of the end portion of the nut nearer the wheel disc in a recess provided on the outboard face of the wheel disc, so that the stud passes through the hole therefore in the wheel disc without coming into contact with the wheel disc.

11. A wheel in accordance with any one of the preceding claims 8 to 10, wherein the second heat shield comprises a lining of thermal insulation material placed between the nut and the wheel disc.

12. A wheel in accordance with any one of the preceding claims 8 to 10 wherein each nut is associated with a bearing plate or flange on the wheel, freely rotatable relative to the nut, and wherein the second heat shield comprises an annular thermally insulating air chamber defined between the end of the nut nearer the wheel disc and the wheel disc, the shape, dimensions and arrangement of the plate or flange being such as to prevent any contact between the wheel and the nut when the latter is fully screwed onto the associated stud.

13. A wheel in accordance with claim 12, characterised in that the second heat shield comprises, in addition, a layer of thermal insulation material between the nut and its flange or plate.

14. A wheel in accordance with claim 12 or claim 13, wherein the second heat shield comprises, in addition, a layer of thermal insulation material interposed between the flange or plate and the wheel.

15. A wheel in accordance with claim 14, wherein the layer of insulation material is moulded over the flange or plate.

1 6. A wheel in accordance with any one of claims 12 to 15, wherein the second heat shield comprises, in addition, thermally insulating air cavities defined by notches formed in the flange or plate associated with each nut.

17. A wheel in accordance with any one of claims 12 to 16, wherein the plate is of bell-shape, defining, with the wheel disc and the associated nut, a supplementary air pocket, participating in the formation of the second heat shield, the elastic deformation of the plate, when the nut is fully screwed onto its associated stud, serving to prevent loosening of the nut under the effect of vibration.

1 8. A nut for mounting a wheel in accordance with any one of the preceding claims on a hub having a threaded stud with which the nut is intended to co-operate, wherein a heat shield is provided to prevent excessive heating of the wheel by the hub via the stud and nut.

19. A nut in accordance with claim 18 wherein the heat shield comprises an enlargement of the bore of the nut at that end thereof nearer to the wheel disc when the nut is threaded onto the associated stud.

20. A nut in accordance with claim 1 8 or claim 1 9 having, at its end nearer the hub when screwed onto the associated stud, a projection for centering the nut in a recess in the outboard face of the wheel disc thereby to prevent any contact between the disc and the stud.

21. A nut in accordance with any one of claims 1 8 to 20, having at its end intended to come into contact with the wheel, a sheath of a thermally insulating material.

22. A nut in accordance with any one of claims 1 8 to 20 engaged by a flange or plate to engage the wheel, the flange or plate being rotatable relative to the nut, wherein the shape, dimensions and arrangement of the flange or small plate prevent any contact between the end of the nut nearer the wheel, when the nut is screwed onto its stud and the wheel the heat shield comprising, in addition, the annular air chamber thus defined between the end of the nut nearer the wheel disc and the wheel disc.

23. A nut in accordance with claim 22, wherein a washer of thermally insulating material is interposed between the nut and its flange or plate.

24. A nut in accordance with claim 22 or claim 23, wherein a lining of a thermally insulating material is moulded onto the face of the flange or plate presented to the wheel.

25. A nut in accordance with any one of claims 22 to 24, wherein the notches formed in the flange or plate of the nut reduce the area of contadt between the nut and its flange or plate.

26. A nut in accordance with any one of claims 22 to 25, wherein the plate has a bell shape defining with the nut a supplementary air pocket, and the elastic deformation of which, when the nut is tightened onto its stud, prevents loosening of the nut under the effect of vibration.

27. A one-piece wheel of fibre-reinforced synthetic resin substantially as herein described with reference to and as illustrated in Figures 1 and 2, Figures 3 and 4, Figure 5 or Figure 12 of the accompanying drawings.

28. A wheel mounting nut substantially as herein described with reference to and as illustrated in Figures 5 and 6, Figure 7, Figure 8, Figure 9, Figure 10, Figures 11 and 12 or Figure 1 3 of the accompanying drawings.