GB2190886A - Wheel assemblies for golf carts - Google Patents

Abstract

The wheel assembly comprises a wheel 10 moulded from a relatively rigid thermoplastics material, and a tyre 11 moulded from a resilient closed-cell foamed polymeric material. The wheel 10 comprises a hub 12 connected to a concentric rim 13; and the rim 13 includes tyre seating means 14 and tyre support means 15. The tyre comprises two spaced apart sidewalls 16 which grip the seating means 14 and are connected by a tread portion 17 which is supported without being stretched by the support means. <IMAGE>

Description

SPECIFICATION Wheel assemblies for golf carts This invention concerns wheel assemblies, for golf carts and like devices for conveying loads over soft or otherwise vulnerable ground.

In orderto avoid the technical complexity, high cost, need for inflation and risk of puncture of pneumatic tyres, it is known to provide the wheels of wheel assemblies with relatively voluminous polymeric foam tyres. Such tyres also have advantages of lesserweight, better shock absorbtion and increased ground contact area in comparison with the similar but relatively narrow section solid rubber or plastics tyres previously used in such wheel assemblies. However, such polymeric foam tyres are expensive td produce and can be difficultto fitto the wheels, and an object of the invention isto enable such problems to be reduced or avoided.

According to the present invention there is generally provided a wheel assembly comprising a tyre of foam polymeric material seated on a rim of a wheel, wherein the rim is gripped by sidewalls ofthe tyre to locate a trend portion of the tyre upon support means provided by the rim so that the thread portion is in a substantially unstretched condition.

Each of the sidewalls may be formed to provide an annular channel in which an edge ofthe rim is embraced; orto provide an annular end portion which is stretched around a seating provided by the rim to radiallycompressthe seating. At leastpartof each sidewall is preferably at least as thick as the thickness or mean thickness of the tread portion.

According to the present invention there is more particularly provided a wheel assembly comprising a wheel and a polymeric foam tyre; wherein the wheel provides spaced apart outwardly directed seating surfaces engaged by sidewalls of the tyre, and provides at least one radially outwardly directed support surface engaged by and within a tread portion ofthetyre.

Thetyre, especiallythetread portion, which constitutes the whole of the tyre between the sidewalls, may thus be made extremely thin in relation to its width, because the margins of the tread portion are supported by the sidewalls and, between these margins, the remainder or intermediate parts ofthe tread portion is or are supported bythe support surface or surfaces, without requiring inflation ofthetyre.

According to the present invention there its further provided a wheel assembly comprising a wheel and a polymeric foam tyre; wherein the tyre is substantially channel or U-shaped in radial cross-section so as to comprise a transverse tread portion extending between spaced apart sidewalls; wherein the wheel provides spaced apart circular seatings engaged by the sidewalls; and wherein the wheel is provided with support means which projects at least partially radially beyond at least one of said seatings to engage and support at least part of the inner surface of the tread portion.

The radial thickness, or mean thickness, ofthe tread portion is preferably no more than one fifth of the width of the tread portion, and is preferably between one tenth and one twentieth of said width.

The support surfaces may be provided on, and support means may comprise, a plurality of circular ribs or flanges spaced apart to supportthetread portion at intervals across the width of the tread portion; orone or more cylindrical portionsto support all or most ofthe width of the tread portion.

The support surfaces or means preferably support axially inwardly directed and radially directed parts of the interiorsurface of each sidewall to restrain or preventtransverseand radial movementthereof.

Adjacent each seating, the wheel may have a terminal flange to overlap and conceal an external edge of a junction between the sidewall and the seating.

Each sidewall may be stepped to provide an intermediate portion which projects, in the axial direction, outwards beyond the seating or the terminal flange, whereby to provide a soft projecting shoulderforthewheel assembly, which shoulder merges smoothly with the tread portion.

The wheel may comprise a main plastics or metal moulding, ortwo similar moulded members, which provides or provide a hub, the seatings orsurfaces and the support surfaces or means.

The two moulded members may be solely or partially held together bythetyre.

The invention will be described further, by way of example, with reference to the accompanying diagrammatic drawings,wherein:- Figure 1 shows part of a fixed embodiment of wheel assembly in radial cross-section, and Figures 2, 3and 4areviewssimilarto Figure 1 of further embodiments ofthe invention.

In all embodiments the wheel assembly comprises a wheel 10 which is moulded from a relatively rigid thermoplastics material, and a tyre 11 moulded from a resilient closed-cell foamed polymeric material.

The wheel 10 comprises a hub 12 connected to a concentric rim 13; and the rim 13 provides a seating means 14 and support means 15. The tyre comprises two spaced apart sidewalls 16 connected by a tread portion 17.

In the first and second embodiments shown in Figures 1 and 2, the wheel is a one piece moulding, and the support means 15 comprises radially outwardly directed members 20 or 20 and 21. The members 20 extend to engage the tread portion, whereas the members 21 (Figure 2) extend to close to the tread portion so asto be engaged bythetread portion when the latter is loaded.

The seating mens 14 provides two spaced apart seatings each of which provides, firstly, a cylindrical radially outwardly directed seating surface which is engaged by a radially inwardly directed end surface at a firstjunction 22 which is concealed by a small lateral flange 23 at the edge of the rim, and, secondly, an annular axially outwardly directed seating surface which is engaged by an axially inwardly directed surface of the sidewall at a second junction 25 which extends radially outwards from the junction 22. It is to be noted that said junctions 22 and 25 need not meet mutually at a right angle, but could merge along an arc, the seating being appropriately curved in transverse cross-section.

Each sidewall has a portion 24 intermediate its inner end and its periphery, which portion 24 is extended axiallyoutwardsto overhang theflange 23, and is offsetfrom the adjacent member 20 or 21.

Referring to Figure3, in the third embodimentthe wheel comprises two identical mouldings 30, which maybe held bya hub insert31 andthetyre 11 so that they abut, but which in this embodiment are held apart by spacing or connecting means 32 indicated in broken lines. The mouldings 30 are formed so that each provides one of the seatings on which one of thesidewalls 16is engaged as hereinbefore described with reference to Figures 1 and 2; but in this embodiment a web 33, which providesthe annular seating surface, extends radially-outwards to a cylindrical flange 34which serves as the support means. The inner ends oftheseflanges 34 may abut.

Referring to Figure 4, in the fourth embodiment the wheel is a one piece moulding formed so thatthe rim 13 is substantially cylindrical so thatthe peripheral surface, between end portions thereof, serves as the support means. These end portions constitute the seating means 14, and each provides an axially outwardly directed end seating surface and a radially inwardly directed inner seating surface; and each sidewall 16 provides an inwardly open channel having internal surfaces which engage the seating surfaces atjunctions 35 and 36 and engage the peripheral surface ofthe end portions at a junction 37 contiguous with the internal surface of the tread portion. The wheel may provide a protective formation 38, indicated in broken lines, to shield the inner end of one sidewall.

All embodiments are arranged so thatthe rim is gripped radially bythe sidewalls to locate the tyre. In the first three embodiments, the sidewalls are moulded so thatthey have to be stretched around the seatings so that the grip is primarily radially directed, whereas in the fourth embodiment, the seatings are gripped in the channel recesses provided bythesidewalls. However,thetread portion is preferably a close, but not significantly stretched,fit around the support means, so thatthe tread portion is not stressed until it is loaded.

By relying upon short sidewalls for location, the thickness of the tread portion between the sidewalls may be very slight in relation to its width, and, whilst in the embodiments shown thethickness is constant, this thickness may vary, e.g. to provide shallow formationsfor interengaging between parts of the support means.

All embodiments are also arranged so that the tyre may befitted to the rim by elastic dilation of one sidewall, preferablythe shortersidewall, and thrusting the rim into the tyrethrough the dilated opening prior to releasing that sidewall to contract onto the seating, thereby avoiding any need for substantial deformation ofthetread portion.

The invention is not confined to details ofthe foregoing examples and manyvariationsare possible within the scope ofthe invention. For example, the sidewalls or one thereof may closely conform to and abut the rim as indicated in broken lines 40 in Figure 1. Further anyfeature or detail of any embodiment may be incorporated in a wheel embodying anyfeature or detail of any other embodiment. For example the right hand sidewall and seating ofthe second embodiment may be omitted, and the rim stepped to provide a cylindrical end portion to accept a sidewall similar two the right hand sidewall ofthefourth embodiment.

Claims (14)

1. Awheel assembly comprising atyreoffoam polymeric material seated on a rim of a wheel, wherein the rim is gripped by sidewalls of the tyreto locate a tread portion of the tyre upon support means provided by the rim so that the tread portion is in a substantially unstretched condition.

2. Awheel assembly as claimed in Claim 1 wherein each of the sidewalls is formed to provide an annular channel in which an edge ofthe rim is embraced; orto provide an annular end portion which is stretched around a seating provided by the rim to radially compress the seating.

3. Awheel assembly as claimed in Claim 2 wherein at least part of each sidewall is at least as thick as the thickness or mean thickness of the tread portion.

4. Awheel assemblycomprising awheelanda polymeric foam tyre; wherein the wheel provides spaced apart outwardly directed seating surfaces engaged by sidewalls of the tyre, and provides at least one radially outwardly directed support surface engaged by and within a tread portion ofthetyre.

5. Awheel assembly comprising a wheel and a polymericfoam tyre; wherein there is substantially channel or U-shaped in radial cross-section so as to comprise a transverse tread portion extending between spaced apartsidewalls; wherein the wheel provides spaced apart circular seatings engaged by the sidewalls; and wherein the wheel is provided with support means which projects at least partially radially beyond at least one of said seatings to engage and support at least part of the inner surface of the tread portion.

6. Awheel assembly as claimed in Claim 2,3,4Or 5wherein the radial thickness, or mean thickness, of thetread portion is no morethan one fifth of the width ofthetread portion.

7. Awheel assembly as claimed in any preceding Claim wherein the support surfaces are provided on, orthe support means comprise, a plurality of circular ribs or flanges spaced apart to supportthetread portion at intervals across the width ofthe tread portion.

8. Awheel assembly as claimed in any preceding claim wherein the support surface provided on, or the support means comprises, one or more cylindrical portions to support all or most ofthetread portion.

9. Awheel assembly as claimed in any preceding claim wherein the support surfaces or means support axially inwardly directed and radially directed parts ofthe interior surface of each sidewall to restrain or prevent transverse.and radial movement thereof.

10. Awheel assembly as claimed in anyone Claims 2 to 9 wherein the wheel has a terminal flange to overlap and conceal an external edge of a junction between the sidewall and the seating or seating surface.

11. Awheel assembly as claimed in anyone of Claims 2 to 10 wherein each sidewall is stepped to provide an intermediate portion which projects, in the axial direction, outwards beyond the seating or the terminal flange, wherebyto provide a soft projecting shoulderforthewheel assembly.

12. Awheel assembly as claimed in any one of Claims 1 toll wherein the wheel comprises a main plastics or metal moulding, or two similar moulded members, which provides or provide a hub, the seatings or surfaces and the support surfaces or means.

13. Awheel assembly as claimed in Claim 12 wherein the two moulded members are solely or partially held together bythetyre.

14. Awheel assembly substantially as hereinbefore described with reference to any Figure of the accompanying drawings.