AU701996B2 - Bicycle wheel - Google Patents

Description

WO 96/25296 PCT/AU96/00074 -1- BICYCLE WHEEL FIELD OF INVENTION The present invention relates to bicycle wheels and to a process for manufacturing bicycle wheels. In particular, the invention relates to hollow form, moulded plastic wheels for bicycles.

BACKGROUND ART Recent developments in bicycle wheel manufacturing technology have seen the advent of hollow form, moulded plastic bicycle wheels that provide superior aerodynamic and light weight performance over the more conventional metal spoked wheels.

As described in Australian Patent Specification No.

36,567/93, hollow form, moulded plastic bicycle wheels have been manufactured by injection moulding two split, mirror image halves of the wheel and assembling the two halves together by suitable fasteners or studs.

However, such wheels have, by virtue of the use of fasteners or studs to retain the two halves together, significant weakness points or weight concentration points that may compromise the overall strength and stability of the wheel. Also, the use of fasteners or studs requires a substantial degree of manual assembly to produce the wheels.

It is an object of the present invention to overcome or at least substantially ameliorate the disadvantages of the prior art.

SUMMARY OF THE INVENTION According to one aspect of the present invention, there is provided a hollow-form, plastic bicycle wheel comprising two substantially mirror image halves of the said wheel, wherein each half comprises a plurality of spokes and a rim, the said spokes and rim comprising a hollowed cavity within which is contained a web-like network of ribs and bridges of identical mirror image configuration, the two halves being pressed together in symmetrical face to face relationship so as to close the hollowed cavities, the ribs and bridges of each half having outer surfaces whereby the outer surfaces of the ribs and bridges of one of the said halves abut against the outer surfaces of the ribs and bridges of the other of the said halves, the said halves being welded together under conditions sufficient to form a continuous link between the web like network of ribs and bridges of :the said halves.

According to another aspect of the present invention, there is provided a hollow-form, plastic bicycle wheel prepared by a process comprising the steps of:producing two substantially mirror image halves of the said a wheel, wherein each half comprises a plurality of spokes and a rim, the said spokes and rim comprising a hollowed cavity within which is contained a web-like network of ribs and bridges of identical mirror image configuration, the ribs and bridges of each half having outer surfaces whereby the outer surfaces of the ribs and bridges of one of the said halves is adapted to abut against the outer surfaces of the ribs and bridges of the other of the said halves when the two halves are pressed together in symmetrical face to face relationship so as to close the hollowed cavities, 27/11/98 pressing the two halves together in symmetrical face to face relationship so as to close the hollowed cavities and cause the outer surfaces of the ribs and bridges of one of the said halves to abut against the outer surfaces of the ribs and bridges of the other of the said halves, and welding the said halves together under conditions sufficient to form a continuous link between the web like network of ribs and bridges of the said halves.

i BRIEF DESCRIPTION OF THE DRAWINGS 10 In order that the present invention may be readily understood and put S" into practical effect, reference will be made to the accompanying drawings, in which:- Fig. 1 is a side elevational view of a hollow-form, plastic bicycle wheel according to a first embodiment of the invention, Fig. 2 is an elevational view of the internal detail of a mirror image ".half of the wheel of Fig. 1, 9^ 27/11/98 PCT/AU96/00074 WO 96/25296 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 is an end sectional view of the two mirror image halves of the wheel of Fig. 1 in the split condition, is an end elevational view of the wheel of Fig. 1 showing the two split substantially mirror image halves welded together, is a sectional view through a portion of the rim of the wheel of Figs. 1 to 4, is an isolated and enlarged end view of a portion of the rim of the wheel of Figs. 1 to 4, is a side elevational view of a hollow form, plastic bicycle wheel according to a second embodiment of the invention, to which a tyre is fitted, is an elevational view of the internal detail of a mirror image half of part of the wheel of Fig. 7, is an end sectional view through AA of the wheel and tyre of Fig. 7, is an enlarged sectional view of the tyre and a portion of the rim engaging the tyre of the wheel shown in Fig. 9, is a sectional view through BB of a spoke of the wheel of Fig. 7, is a side elevational view of a hollow form, plastic bicycle wheel according to a third embodiment of the invention, and Fig. 8 Fig. 9 Fig. 10 Fig. 11 Fig. 12 WO 96/25296 PCT/AU96/00074 -4- Fig. 13 is a sectional view through CC of a mirror image half of the rim of the wheel of Fig.

12.

MODE FOR CARRYING OUT THE INVENTION The bicycle wheel 10 of Figs. 1 to 6 is of a hollowform, moulded plastic type having a central hub portion 11, an annular rim 12 and five radially extending spokes 13 that are symmetrically located at equal angular spacings about the hub portion 11 so as to connect the central hub portion 11 to the rim 12. The wheel 10 is, in this instance, made of glass-filled thermoplastic resin.

The annular rim 12 has a peripheral channel 14 (see Fig. 4) to receive a tyre (not shown).

The hub portion 11 has a bore 15 extending therethrough to receive an axle bearing or shaft arrangement (not shown) which will enable the wheel to rotate thereabout. The outer ends of bore 15 are enlarged to receive lock nuts, spacers and other retaining members.

The hub portion 11, rim 12 and spokes 13 are aerodynamically shaped to provide minimal wind resistance and stable handling during use.

The wheel 10 is manufactured by firstly producing two substantially mirror-image halves 16 and 17 as shown sideon in Fig. 3.

The internal detail of the mirror image half 16 of Fig.

2 comprises a web-like network of ribs 21 and bridges 22 formed of the same thermoplastic resin material as the other parts of the wheel WO 96/25296 PCT/AU96/00074 The ribs 21 extend radially outwardly from the bore to the rim 12 and each rib 21 is located centrally through its corresponding spoke 13. The bridges 22 are of various forms. Transverse bridge 25 connect the ribs 21 to the outer walls 24 of the spokes 13. Flared bridges 28 connect the ribs 21 to the rim 12 and arcuate bridges 29 connect the ribs 21 to each other. Rim bridges 30 connect the inner wall 26 to the outer wall 27 of the rim 12. Each of the ribs 21 and bridges 22 have outer surfaces that are in the same plane.

Each half 16, 17 is produced by an injection moulding technique whereby a plastic material, such as glass-filled thermoplastic resin, is injected into a very accurately manufactured moulding die. Glass-filled thermoplastic resin imparts strength and rigidity to the finished wheel.

The substantially mirror-image halves 16 and 17 are then placed in a nest of a vibration welder, for instance, which is designed to weld thermoplastic parts together.

Vibration welding is an improved friction welding technique capable of producing strong pressure-tight joints in thermoplastic parts. With vibration welding, frictional heat is generated by pressing the surfaces of two plastics parts together and vibrating the parts through a small relative displacement in the plane of the joint.

In the particular case of the present invention, the two halves 16 and 17 are clamped together as shown in Fig.

4 in symmetrical relationship such that there is an exact meeting or abutting of corresponding outer surfaces at the WO 96/25296 PCT/AU96/00074 -6hollowed side of each half (see sectional detail in Fig.

Frictional heat is then generated between the abutting corresponding outer surfaces or joint interfaces by vibrating one of the halves through a peak to peak reciprocating displacement of 0.8 to 3.5 mm at a frequency of 120 or 240 cycles per second. When a molten state is reached at the joint interfaces, the vibration is terminated and the halves are automatically aligned so that, with a brief maintenance of clamping pressure, the molten plastic at the joint interfaces can solidify to form a continuous link of bonded plastic between the two halves.

Figs. 5 and 6 show flash traps 30 and 31 at all visible joint interfaces in the wheel rim 12. If desired, similar flash traps may be present elsewhere along the web-like network of joint interfacing ribs and bridges. The flash traps 30 and 31 are designed to take up any overflow of molten plastic during hardening and bonding of the two mirror-image wheel halves and so preserve a substantially smooth external surface of the rim.

The bicycle wheel 40 of Figs. 7, 8 and 9 is also of a hollow-form, moulded plastic type having a central hub portion 41, an annular rim 42 and three radially extending spokes 43 that are symmetrically located at equal angular spacings about the hub portion 41 and connect the central hub portion 41 to the rim 42. The wheel 40 is made of glass-filled thermoplastic resin.

The annular rim 42 has a peripheral channel 44 (see Fig. 9) that receives a tyre WO 96/25296 PCT/AU96/00074 -7- The hub portion 41 has a central bore through which is located an axle bearing arrangement 90 (see Fig. 9) which will enable the wheel 40 to rotate thereabout. Each of the outer ends of the shaft 46 of the axle bearing arrangement 90 receive a lock nut 47, a spacer and, located therebetween, an end bracket portion 48 of a fork 49 for the wheel 41. In the form shown in Fig. 9, the wheel 40 is adapted for use as a front wheel of a bicycle. For use as a rear wheel, a sprocket may be readily welded or otherwise affixed to the hub 41 of the wheel As with the wheel 10 of Figs. 1 to 6, the hub portion 41, rim 42 and spokes 43 of wheel 40 are aerodynamically shaped to provide minimal wind resistance and stable handling during use.

There is a valve assembly 50 for inflating and deflating the tyre 45 which provides sealable air access through the rim 42 via passageway 51 (see Fig. 8).

As with the wheel 10 of Figs. 1 to 6, the wheel 40 is manufactured by, firstly, producing two substantially mirror-image halves (only a portion of half 52 is shown in Fig. 8) and, secondly, placing both halves in face to face relationship in a nest of a vibration welder so as to weld the web-like network of ribs and bridges together in the manner as described with reference to the wheel The web-like network of ribs and bridges shown in respect of the wheel half portion of Fig. 8 is configured differently to that of the wheel half of Fig. 2, owing, in large part, to the presence of only three spokes, rather WO 96/25296 PCT/AU96/00074 -8than five, and to the specific high performance and strength requirements associated with a three spoked wheel.

Also, the particular configuration of ribs and bridges may assist in the stabilization and performance of the vibration welding process. As will be readily appreciated by those skilled in the art, the configuration of the weblike network of ribs and bridges may differ in each wheel produced by the process of the present invention depending on the wheel performance requirements for which structural features play a significant role.

The rim and tyre arrangement of Fig. 10 shows flash traps 54, 55 at the various externally presented locations where vibration welding of corresponding surfaces will occur between the two wheel halves. Connected along the circumference of the rim 42 is a rubber band 56 for the protection of the inner tube (not shown) of the tyre Fig. 11 shows flash traps 57, 58 at the outwardly facing or visible joint interfaces of the two halves of the spoke 43.

The bicycle wheel 60 of Fig. 12 is of substantially the same construction as the wheel 40 and is manufactured according to the same process of the invention, but differs, when viewed side-on, in that its annular rim 61 is of a non-uniform thickness, tending to be narrower or tapering as the rim 61 approaches the spokes 62, 63 and 64.

Such a rim configuration significantly reduces the weight of the wheel 60 over the wheel 40 and may confer improved aerodynamic features. An appropriate web-like network of WO 96/25296 PCT/AU96/00074 -9ribs and bridges provides internal structural support of the rim 61.

Although not shown, an air valve assembly may be present through the rim 61 at any one of its narrowest points The rim half 65 shown sectionally in Fig. 13 differs from that shown (joined) in Fig. 10 by the relocation of the span portion 66 closer to the position of the tyre.

This relocation of the span portion 66 substantially reduces the weight of the overall rim, thereby further improving the performance of the wheel It is notable that the overall bond between the two halves of each of the wheels 10, 40 and 60 has a strength that approaches or is equal to the strength of the original solid plastic material.

Apart from achieving the desired strength of the resultant bond between the two halves, the welding technique also creates an integral wheel that is lightweight and has little or no excess aerodynamic impediment.

A major advantage of vibration welding lies in its application to large irregularly-shaped parts. It also readily lends itself to automation by robotics.

A similar result may be achieved by use of ultrasonic welding techniques.

Welding the two halves together to form an integral wheel has the advantage that there are no significant weakness or weight concentration points in the wheel, such WO 96/25296 PCT/AU96/00074 as may be present if studs or fasteners were used to join the halves together.

Another advantage is that the wheel can be dynamically balanced at the stage of injection moulding each half of the wheel, since the welding technique does not necessitate the fitting onto the wheel of any additional parts. A better and more permanently balanced wheel will therefore result from the process of the present invention.

Various modifications may be made in details of design and construction without departing from the scope or ambit of the invention.

Claims (4)

1. A hollow-form, plastic bicycle wheel comprising two substantially mirror image halves of the said wheel, wherein each half comprises a plurality of spokes and a rim, the said spokes and rim comprising a hollowed cavity within which is contained a web-like network of ribs and bridges of identical mirror image configuration, the two halves being pressed together in symmetrical face to face relationship so as to close the hollowed cavities, the ribs and bridges of each half having outer surfaces "whereby the outer surfaces of the ribs and bridges of one of the said halves Il: abut against the outer surfaces of the ribs and bridges of the other of the said halves, the said halves being welded together under conditions sufficient to form a continuous link between the web like network of ribs and bridges of the said halves.

S2. The bicycle wheel of claim 1 wherein each of the two substantially o mirror image halves of the bicycle wheel are produced by injection moulding of a plastic material selected from the group consisting of fiber-reinforced plastic and glass-filled thermoplastic resin.

3. The bicycle wheel of claim 1 or claim 2 wherein the said halves are vibration welded together.

4. A hollow-form, plastic bicycle wheel prepared by a process comprising the steps of:- producing two substantially mirror image halves of the said wheel, wherein each half comprises a plurality of spokes and a rim, the said spokes and rim comprising a hollowed cavity within which is contained a web-like network of ribs and bridges of identical mirror image configuration, the ribs and bridges of each half having outer surfaces whereby the outer surfaces of the ribs and bridges of one of the said halves is adapted to abut against the outer surfaces of the ribs and bridges of the other of the said halves when the two halves are pressed together in symmetrical face to face relationship so as to close the hollowed cavities, pressing the two halves together in symmetrical face to face relationship so as to close the hollowed cavities and cause the outer surfaces of the ribs and bridges of one of the said halves to abut against the outer surfaces of the ribs and bridges of the other of the said halves, and welding the said halves together under conditions sufficient to 0: form a continuous link between the web like network of ribs and bridges of 0 the said halves. A hollow-form, plastic bicycle wheel substantially as hereinbefore described with reference to the accompanying drawings. Dated this 27th day of November 1998. ERNEST L KILPATRICK By his Patent Attorneys PETER MAXWELL ASSOCIATES