WHEEL RIM FOR A PNEUMATIC TYRE

Abstract: A one piece wheel rim for a pneumatic tyre having a pair of axially spaced apart tapered bead seats, (1) a tyre retaining flange (3) axially outwards of each bead seat, (1) said flange (3) being in its radially inner regions at an angle of A degrees to the radial direction of the wheel and being characterised by having a reduced height portion (7) having a length of 0.25 to 0.5 times the bead seat circumference and the reduced height being such that the flange height, (h) measured from the heel point, which is the point of intersection of the nominal diameter and the nominal wheel width is in the range of 0.15 to 0.6 times the height (H) of the remainder of the flange, characterised in that the portion of the flange which is radially outside the reduced height portion is at an angle B degrees where the angle B is greater than angle A to the radial direction so that a tyre bead fitted to the wheel rim seats against the flange (3) only to the height (h) of the reduced height portion around the full circumference of the tyre.

Description: This invention relates to a wheel rim for a pneumatic tyre and in particular to a single piece wheel rim having two axially spaced tapered bead seats on which a tyre may be mounted. It relates in particular to a wheel rim of the type disclosed in our co-pending European Patent Application No. 88300557.1, published on 17.08.88 under the number EP-A-0 278 615, and which falls within the terms of AA. 54(3) EPC, where a one piece wheel rim is provided having a pair of axially spaced apart tapered bead seats, tyre retaining flange axially outwards of each bead seat and characterised by one flange having a reduced height portion having a length of 0.25 to 0.5 times the bead circumference and the reduced height portion being such that the flange height, measured from he heel point, which is the point of intersection of the nominal diameter and the nominal wheel width, is in the range of 0.15 to 0.6 times the height of the remainder of the flange to allow tyre fitting. The wheel rim of this prior invention may in some circumstances cause chafing of the tyre in the bead region adjacent to the cut-away portion of the flange, and it is one object of the present invention to provide a wheel rim of one piece construction which has all the advantages of the previous application but which in addition avoids chafing of the tyre bead adjacent to the cut-away region. According to the present invention a one piece wheel rim for a pneumatic tyre is provided having a pair of axially spaced apart tapered bead seats, a tyre retaining flange axially outwards of each bead seat, said retaining flange being in its radially inner region at an angle of A degrees to the radial direction of the wheel and having a height that, measured from the heel point, which is the point of intersection of the nominal diameter and the nominal wheel width, is in the range of 0.15 and 0.6 times the height of the remainder of the flange, said retaining flange having a portion of reduced height having a length of 0.25 to 0.5 times the bead seat circumference wherein the portion of the retaining flange which is axially outside the inner region is at an angle B degrees, where angle B is greater than angle A, to the radial direction so that a tyre bead fitted to the wheel rim seats against the tyre retaining flange only to the height of the reduced height portion around the full circumference of the tyre. Preferably the angle B of the radially outer portion of the wheel rim is substantially greater than angle A; for example angle B when measured from the radial direction is preferably in the range of 10 to 75 degrees and more preferably in the range of 60 to 70 degrees. The overall height of the flange, measured in the radial direction, is preferably similar to the flange height used in a conventional rim. The resultant assembly, in having the flange cut-away, still allows the wheel to have only a minimal fitting well which is of substantially smaller depth than a normal wheel rim well and thus the wheel rim allows for a greater brake volume than for a conventional wheel rim. As in the case of the previous invention the minimal fitting well may be circumferentially continuous or indeed in some preferred arrangements may be very short in the circumferential direction. The minimal well may comprise only a flat connecting base between the axially inner edges of the tapered bead seats so that in fact the wheel appears to have no well whatsoever. The reduced height portion of the flange has limited effective thickness so that it projects in the axial direction of the wheel rim only a short distance from the tyre bead contacting flange face. This is to ensure that the necessary skew of the tyre as it is fitted with part of the bead in the shallow well does not cause even the reduced height portion to abnormally tension the bead reinforcement on assembly of the tyre to the wheel rim. The reduced height portion, where it joins the portion sloping at angle B, may be smoothly radius from one portion to the other or may have a progressively rising region which has its surface at the angle B but which gradually rises in height until the full flange extension B is provided. Preferably one end of the cut-away portion projects suddenly to the full flange shape at the angle B and at the other end of the cut-away there is a progressive gradual slope in the portion of the flange at angle B. Further aspects of the present invention will become apparent from the following description of one embodiment of the invention in conjunction with the attached diagrammatic drawings in which Fig.1. shows a side view of a wheel rim according to the present invention Fig.2. shows a partial cross section of the wheel rim taken on the line II in Fig.1. Fig.3 is a plan view taken in the direction of arrow X on Fig.2. Fig.4. is a perspective scrap view of the flange at one end of the cut-away region in Figs.1 & 2 Figs.5 & 6 show alternative flange shapes to the embodiment of Fig.1. The primarily embodiment of Figs 1, 2, 3, & 4 is a 22.5 inch diameter truck wheel rim having a pair of tapered bead seats 1, each at an angle of 15 degrees to the axial direction of the wheel rim and a central flat web 2 interconnecting the axially inner edges of the tapered bead seats 1. Each bead seat has at its outer end a tyre retaining flange 3 which is at an angle A to the radial direction of the wheel rim. The angle A is in this case 20 degrees as used on all such 22.5 inch one piece truck wheel rims. The height of the tapered flange 3, measured in the radial direction is indicated by dimension h and this height is 6mm. The conventional flange shape for a 22.5 inch rim is shown by the broken line 4, and this has a height of 12.7mm. However, as can be seen the present wheel rim has the axially outermost portion 5 formed at a second angle B to the radial direction. In this embodiment angle B is 60 degrees and the radially outer surface of the flange 5 continues at this angle of 60 degrees until the conventional flange height H of 12.7mm is reached whereupon the flange has a small turnover portion 6. Both flanges of the wheel rim have this same shape. The inner flange, or back flange is, however, modified as can clearly be seen in Figs.1 & 2 in that it includes a reduced height portion 7. The reduced height portion comprises a cutting away of the portion of the flange which is at angle B so that for a part of the circumference of the wheel rim the region 5 does not exist. The cut-away portion 7 thus has an effective flange height of 6mm and this extends around the circumference of the wheel rim for a distance RR which means that the flange around the remainder of the wheel rim marked by the region SS is of the full flange size. One end of the cut-away flange has a steeply rising region 8 and the other end of the cut-away portion has a gradually rising region 9. The cut-away portion has a length of 0.5 times the circumference of the wheel rim (although in figure 1 it is shown shorter for reasons of clarity). The wheel takes a conventional 22.5 inch radial tubeless truck tyre and the tyre can be fitted in a similar manner to conventional assembly except that the tyre must be positioned so that when the bead is engaged in the very shallow well between the two tapered bead seats the other side is at the reduced flange portion. Thus to use levers to complete bead fitting entails levering the bead over the reduced height portion and this can advantageously be done by taking advantage of the steeply rising portion 8. Tyre removal or stripping is the same procedure and the tyre can be removed from the wheel rim without difficulty. Similar constructions of wheel rim may be used for cars and other heavy vehicles and it is not essential for the beat seats to be tapered at the 15 degree angle described. In fact a similar assembly can be used for all size wheel rims from small cars to heavy trucks. The wheel rim has all the advantages of the originally mentioned European Patent Application in the name of the applicants but in addition the present wheel rim has a constant height, tyre contacting flange 3 around the full circumference of both wheel rim flanges and the higher portions of the flanges 5 do not normally contact the tyre. Thus the tyre is not subject to chafing at the edges of the cut-away region but the remainder of the flanges in the regions SS are of the same height as conventional flanges and thus provide the conventional degree of safety in the event of tyre dislodgement following a puncture.

Claims: 1. A one piece wheel rim for a pneumatic tyre having a pair of axially spaced apart tapered bead seats (1), a tyre retaining flange (3,5,6,7) axially outwards of each bead seat (1), said retaining flange being in its radially inner regions (3) at an angle of A degrees to the radial direction of the wheel and having a height (h) that, measured from the heel point, which is the point of intersection of the nominal diameter and the nominal wheel width, is in the range of 0.15 to 0.6 times the height (H) of the remainder of the flange, said retaining flange having a portion (7) of reduced height (h) having a length of 0.25 to 0.5 times the bead seat circumference wherein the portion (5) of the retaining flange (3,5,6,7) which is axially outside the inner region (3) is at an angle B degrees, where the angle B is greater than angle A, to the radial direction so that a tyre bead fitted to the wheel rim seats against the tyre retaining flange only to the height (h) of the reduced height portion (7) around the full circumference of the tyre. 2. A one piece wheel rim according to claim 1 characterised in that the angle B of the radially outward portion of the wheel rim is substantially greater than angle A. 3. A one piece wheel rim according to claim 2 characterised in that the angle B is in the range of 10 to 75 degrees. 4. A one piece wheel rim according to claim 2 characterised in that the angle B is in the range of 60 to 70 degrees. 5. A one piece wheel rim according to any one of claims 1 to 4 characterised in that a minimal well comprises a flat connecting base (2) between the axially inner edges of the tapered bead seats (1) so that the wheel has no apparent well. 6. A one piece wheel rim according to any one of claims 1 to 5 characterised in that the reduced height portion of the flange (7) has a limited effective thickness so that it projects in the axial direction of the wheel rim only a short distance from the tyre bead contacting flange face. 7. A one piece wheel rim according to any one of claims 1 to 6 characterised in that the reduced height portion, (7) where it joins the portion sloping at an angle B, is smoothly radiused from one portion to the other.

Inventors: KEMP, IAN
Applicants: SUMITOMO RUBBER INDUSTRIES LIMITED
Application year: 1989
Main classification: B60B21
IPC codes: B60B21