CA1081282A - Tyre and wheel rim assemblies - Google Patents
Tyre and wheel rim assembliesInfo
- Publication number
- CA1081282A CA1081282A CA338,994A CA338994A CA1081282A CA 1081282 A CA1081282 A CA 1081282A CA 338994 A CA338994 A CA 338994A CA 1081282 A CA1081282 A CA 1081282A
- Authority
- CA
- Canada
- Prior art keywords
- bead
- tyre
- wheel rim
- range
- radially
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 230000000712 assembly Effects 0.000 title description 7
- 238000000429 assembly Methods 0.000 title description 7
- 239000011324 bead Substances 0.000 claims abstract description 182
- 229920001971 elastomer Polymers 0.000 description 23
- 230000002787 reinforcement Effects 0.000 description 18
- 239000000463 material Substances 0.000 description 14
- 229910000831 Steel Inorganic materials 0.000 description 13
- 239000010959 steel Substances 0.000 description 13
- 238000012360 testing method Methods 0.000 description 12
- 238000010276 construction Methods 0.000 description 10
- 239000004744 fabric Substances 0.000 description 9
- 229920001875 Ebonite Polymers 0.000 description 8
- 239000004677 Nylon Substances 0.000 description 7
- 229920000297 Rayon Polymers 0.000 description 7
- 229920001778 nylon Polymers 0.000 description 7
- 210000002320 radius Anatomy 0.000 description 7
- 239000002964 rayon Substances 0.000 description 7
- 150000001875 compounds Chemical class 0.000 description 5
- 230000006835 compression Effects 0.000 description 5
- 238000007906 compression Methods 0.000 description 5
- 239000000945 filler Substances 0.000 description 4
- 150000002500 ions Chemical class 0.000 description 4
- 230000014759 maintenance of location Effects 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 238000007789 sealing Methods 0.000 description 4
- 239000000314 lubricant Substances 0.000 description 3
- 230000000717 retained effect Effects 0.000 description 3
- 239000004753 textile Substances 0.000 description 3
- 238000002788 crimping Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 230000007935 neutral effect Effects 0.000 description 2
- 239000000565 sealant Substances 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- SZUVGFMDDVSKSI-WIFOCOSTSA-N (1s,2s,3s,5r)-1-(carboxymethyl)-3,5-bis[(4-phenoxyphenyl)methyl-propylcarbamoyl]cyclopentane-1,2-dicarboxylic acid Chemical compound O=C([C@@H]1[C@@H]([C@](CC(O)=O)([C@H](C(=O)N(CCC)CC=2C=CC(OC=3C=CC=CC=3)=CC=2)C1)C(O)=O)C(O)=O)N(CCC)CC(C=C1)=CC=C1OC1=CC=CC=C1 SZUVGFMDDVSKSI-WIFOCOSTSA-N 0.000 description 1
- NLZUEZXRPGMBCV-UHFFFAOYSA-N Butylhydroxytoluene Chemical compound CC1=CC(C(C)(C)C)=C(O)C(C(C)(C)C)=C1 NLZUEZXRPGMBCV-UHFFFAOYSA-N 0.000 description 1
- 101100536893 Schizosaccharomyces pombe (strain 972 / ATCC 24843) thi9 gene Proteins 0.000 description 1
- 241000950638 Symphysodon discus Species 0.000 description 1
- 230000001133 acceleration Effects 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000004323 axial length Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 229940126543 compound 14 Drugs 0.000 description 1
- 239000000806 elastomer Substances 0.000 description 1
- 239000013536 elastomeric material Substances 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- HOQADATXFBOEGG-UHFFFAOYSA-N isofenphos Chemical compound CCOP(=S)(NC(C)C)OC1=CC=CC=C1C(=O)OC(C)C HOQADATXFBOEGG-UHFFFAOYSA-N 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 238000007788 roughening Methods 0.000 description 1
- 239000012812 sealant material Substances 0.000 description 1
- 125000006850 spacer group Chemical group 0.000 description 1
- 238000004804 winding Methods 0.000 description 1
Landscapes
- Tires In General (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A one-piece wheel rim for a tubeless pneumatic tyre is disclosed herein. The radially outer profile of the wheel rim, considered in a plane containing the axis of the wheel rotation, comprises in sequence from one edge of the wheel profile: a radially extending bead retaining flange having a radially outer edge which is turned axially outwardly; a curved seating portion for the heel of a tyre bead; a substantially straight main bead seating portion which tapers radially in-wardly towards the axially inner regions of the wheel rim; an open bead toe locating groove immediately adjacent to said bead seating portion formed by, again in sequence:- a radially inwardly curving axially outer groove edge portion having a radius in the range of 5mm to 8mm; an outwardly concave groove base portion having a radius in the range of 3mm to 5mm; and a radially inwardly curving axially inner groove edge portion having a radius in the range of 5mm to 8mm; a substantially straight flat ledge portion; a central tyre-fitting well por-tion having a diameter substantially smaller than the main bead seating portion and arranged to allow tyre fitting over the tyre retaining flange; a second open bead toe locating groove formed by, again in sequence:- a radially inwardly curving axially inner groove edge portion having a radius in the range of 5mm to 8mm; an outwardly concave groove base portion having a radius in the range of 3mm to 5mm; and a radially inwardly curving axially outer groove edge portion having a radius in the range of 5mm to 8mm; a substantially straight main bead seating portion which tapers radially inwardly towards the axially inner regions of the wheel rim; and a radially extending bead retaining flange having a radially outer edge which is turned axially outwardly.
A one-piece wheel rim for a tubeless pneumatic tyre is disclosed herein. The radially outer profile of the wheel rim, considered in a plane containing the axis of the wheel rotation, comprises in sequence from one edge of the wheel profile: a radially extending bead retaining flange having a radially outer edge which is turned axially outwardly; a curved seating portion for the heel of a tyre bead; a substantially straight main bead seating portion which tapers radially in-wardly towards the axially inner regions of the wheel rim; an open bead toe locating groove immediately adjacent to said bead seating portion formed by, again in sequence:- a radially inwardly curving axially outer groove edge portion having a radius in the range of 5mm to 8mm; an outwardly concave groove base portion having a radius in the range of 3mm to 5mm; and a radially inwardly curving axially inner groove edge portion having a radius in the range of 5mm to 8mm; a substantially straight flat ledge portion; a central tyre-fitting well por-tion having a diameter substantially smaller than the main bead seating portion and arranged to allow tyre fitting over the tyre retaining flange; a second open bead toe locating groove formed by, again in sequence:- a radially inwardly curving axially inner groove edge portion having a radius in the range of 5mm to 8mm; an outwardly concave groove base portion having a radius in the range of 3mm to 5mm; and a radially inwardly curving axially outer groove edge portion having a radius in the range of 5mm to 8mm; a substantially straight main bead seating portion which tapers radially inwardly towards the axially inner regions of the wheel rim; and a radially extending bead retaining flange having a radially outer edge which is turned axially outwardly.
Description
~81~8~ `
This invention relates to wheel rims.
In conventional tyre and wheel rim assemblies the tyre beads are retained on their respective bead seats by means of the internal air pressure and frictional restraint due to the compression in the elastomer under the bead wire ; when fitted onto the tapered seat of the rim. Lowering the air pressure in the tyre, however, lessens the reten-tion force from internal air pressure and eventually at a sufficiently low internal pressure the assembly reaches an unsafe condition in which the tyre beads may be dis-, placed from their seats by sideways force such as is generated in an accident avoidance manoeuvre.
The European motor industry uses a variety of teststo check bead dislodgement. A typical test is carried out by testing a tyre and wheel rim assembly as the outer front wheel i.e. a left-hand or near side in a right-hand J turn test at 25 mph. The test comprises straight running at 25 mph and then the sudden application of full steering lock. The test is repeated at progressively reducing tyre inflation pressures until dislodgement occurs. Usually the pressure reduction steps are 2 psi. Typical production radial ply car tyres normally dislodge a bead at air pressures of the order of 5-15 psi in such a test.
Typical tubeless radial ply car tyres normally dislodge a bead at pressures of the order of 5-15 psi in such a test.
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Dislodgement of a tyre bead ~rom its seat a~fects vehicle control. In the use of wheels which include a well to allow tyre fitting there i5 generally a grave danger of complete separation of the tyre from its wheel rim.
In the use of a vehicle, cornering generates sideways forces which displace the tread laterally with respect to the wheel rim. These forces are transmitted by the tyre carcass to the tyre bead. In the region of the tyre adjacent to the ground contact area axial forces (i.e. in the direction of the tyre axis) and turning moments (i.e. about a circumferential line through the bead) are generated. In the absence of air pressure these forces may be sufficient to produce lifting of the heel of the bead thus reducing the frictional force between the bead base and the bead seat on the rim which, in said deflated state, is the only force which retains the bead on it~ seat. As a result the bead moves down its tapered bead seat laterally inwardly of the rim flange reducing the tension in the bead `~
wire and, very rapidly the residual bead retaining force becomes less than the dislodging forces and the bead leaves itB seat and ~a 119 into the well.
Previous attempts to solve this problem have centred around the use of wheel rims which do not have a well. The resultant flat-based rim obviates the danger of tyre wheel separation but has the disadva~tage that the tyre beads are usually able to move axially between the spaced-apart flanges.
Thus the sideways force which can be transmitted between the wheel and the ground changes suddenly from zero when a bead is moving across the rim to a maximum when both beads are ~ , : - ' ; :
: ' .. .. ..
- together against a ~l~nge. ~h10 may, in the extreme, cau~e lo~e o control of the vehiclel.
Thi~ i~ equally true for a well based rim h~ving a filling device, a wheel rim which ha~ a fitting well closed by crimping after tyre fitting or a divided wheel rim as~embl~.
A divided wheel rim y~tem require~ several extra components with consequent disadvantages in sealing the air chamber of the tyre, increased co~t, increa~ed weight and ~ increased complexity for servicing. The well illing ~ystem ~ 10 also increases the assembly weight, cost and complicates servicing even though a one-piece wheel rim may then be utilised. None of these previous attempts, however, - overcome the problems o side force transmission when a bead moves axially acro~s the rim.
Bead spacer rings which are rigid circumferentially ~ -... .
extending rings illing the space between the two beads have been propo~ed for u~e with divided whcel rims to hold both 'I beads in place, ~ee for example, U.K. Patent No. 222,768.
Such device~ provide the required properties but add yet another component to the already complex divided wheel rim as0embly .
Another modiication to a divided wheel rim having a flat base and no well i~ disclosed in U.K. Patent ~o.
1,395,714 in which a notch is formed between two wheel rim components at the outboard bead side of the flat base rim and an extended rubber toe is provided on the bead which rests freely in the notch. This assembly is still subject to all the complications of divided wheel rims including the _ . , .
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air sealing problem and use~ a flat based wheel rim for safety in high side ~orce con~itions.
Yet another system i~ shown in U.K. Patent No.
890,959 where a divided wheel rim i9 proposed in which a fabric reinforced, rubber covered extension of the bead is clamped between the rim parts to seal the assembly. Whilst this may retain the bead, effective sealing depends on accurate assembly and clamping of the bead extension.
The system is al~o still subject to the general dis-advantages of divided wheel rims.
One piece flat based wheel rims are known and one such assembly is disclosed in U.K. Patent ~o. 1,348,891 where a one-piece wheel rim has provided a well for tyre fitting which is subsequently closed by permanently crimping it closed so as to provide a flat based rim. Such an assembly has the further disadvantage of it being necessary to destroy the rim to repair the tyre or check the inside ~or damage.
Still another ~y~tem is to provide a well in the normal bead ~eat area at on~ aide of a flat ba~ed wheel rim ~ ;
and having ~itted the tyre over the flange~ u~ing thi~ well to pre~s both beads again~t ~he ~lange furthest from the well and insert a well filler which subse~uentl~ form~ the bead ~eat. Such a ~ystem ie di9closed in U.S. Patent No.
3,884j286.
Attempts to overcome the problems of bsad retention and yet allow the use o~ a normal well in a wheel rim have included small circumferentially extending humps formed in the rim adjacent to the bead. Such humps can be 1.7 mm-in ' ' ~'~,,, ' ' ' . ' . ' . I
106~1Z8;~
height relative to the bead seat toe diameter but, in any case, these must be limited to dimensions which permit a tyre to be fitted to its seats by inflation pressure without damage. The sideways forces generated by the road when the tyre is deflated greatly exceed the force generated by the inflation pressure and thus any hump which allows tyre fitting cannot prevent bead dislodgement and thus the tyre bead is able to enter the well.
One-piece wheel rims having radially movable stops adjacent to the bead seat are also known but here again to provide the necessary stop movement adds complication, cost and air sealing problems to the assembly.
More recently in U.S. Patent ~o. 3,951,192 it has been proposed to provide hook-like extensions ormed on the outer lower sidewall areas of the tyre and shaped to engage around the wheel rim flange so as to resist bead movement.
However, sideway9 ~orces rotate the bead with resulting heel li~ting and thus this construction cannot, in our experience, be satisfactory. In addition they are subject to the like-lihood o~ damage rom kerbstones.
~hus all known previou~ attempts to provide or posi~ive bead retention and thus the ability to control a vehicle even when a tyre is deflated have either not provided a solution or have been complex and thexefore too costly.
The automobile industry currently fits tyres to rims automatically using irstly a machine which rolls both beads over one flange using the well to give the necessary clearance ~ and secondly a so-called 'explosion' inflation device which :- .
, '............... ` ' ' ' almost instantaneously inflates the tyre and forces the beads onto their respective bead seats. This means that the industry requ~res tyre and wheel rims compatible with this machinery~
We have investigated the phenomena of the forces involved in dislodging the beads of a tyre from a wheel rim when on a vehicle. We have also investigated the phenomena of the forces involved in fitting tyres to and removing tyres from wheel rims. We have ound that the road generated forces involved in tyre bsad dislodgement are quite different from the forces involved in the removal of a tyre from the wheel rim with the wheel tyre as~embly removed from the vehicle for tyre replacement or repair.
Accordingly we have utilised the difference between the road generated dislodgement force~ and the tyre removal force~ to provide a bead lock which obviate~ the above problems i~
and allow3 for khe ~afe use of a one-piece wheel rim.
':, . '~' ~l 20 .' .
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According to one aspect of the present invention, a one-piece wheel rim for a tubeless pneumatic tyre wherein the radially outer profile of the wheel rim considered in a plane containing the axis of the wheel rim comprises, in se~uence, from one edge of the wheel rim profile:- a radially extending bead retaining flange having a radially outer edge which is turned axially outwardly; a curved seating portion for the heel of a tyre bead; a substantially straight main bead seating portion which tapers radially inwardly towards the axially inner regions of the wheel rim; an open bead toe locating groove immediately adjacent to said bead seating portion formed by, again in sequence:- a radially inwardly curving axially outer groove edge portion having a radius in the range of 5mm to 8mm; an outwardly concave groove base portion : having a radius in the range of 3mm to 5mm; and a radially in-wardly curving axially inner groove edge portion having a radius in the range of 5mm to 8mm; a substantially straight flat ledge portion; a central tyre-fitting well portion having a diameter substantially smaller than the main bead seating portion and arranged to allow tyre fitting over the tyre re-taining flange: a second open bead toe locating groove formed by, again in sequence:- a radially inwardly curving axially inner groove edge portion having a radius in the range of 5mm to 8mm;
: an outwardly concave groove base portion having a radius in the range of 3mm to 5mm; and a radially inwardly curving axially outer groove edge portion having a radius in the range of 5mm to 8mm; a substantially straight main bead seating portion which tapers radially inwardly towards the axially inner regions of the wheel rim; and a radially extending bead retaining flange having a radially outer edge which is ~urned axially outwardly.
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Several embodiment~ of the present invention will now be described, by way of example only, to ~how the ~co~e of application of the present invention~ The embodiments will each be described in conjunction with diagrammatic drawings which relate to each embodiment as $ollows:-The first embodiment is a 180 65 SR 340 radial tyre and wheel rim assembly. A cross-sectional profile of the assembly is shown in Fiyure 1, a detailed half-section of the tyre is shown in Figure 2 and the rim is shown in ;~10 detailed cross-section in Figure S.
The second embodiment is a 180 65 SR 340 'Denovo' (Registered ~rade ~ark) run-flat type of tyre/wheel rim a~sembly and a cross-sectional profile of the assembly is shown in Figure 3 a detailed half-section of the tyre is -15 shown in Figure 4 and the wheel rim is shown in detailed ,, ~ .
cross-section in Figure 5.
Figures 6, 7, 8, 9, and 10 are shown to assist in ;-the following description of the operation o the invention based on the current understanding of said i~vention and , . ..
;20 show respectively a cross-section of a t~re and wheel rim assembly in the ground-contacting area running deflated, an eniarged detail of the bead and wheel rim bead seat area in the condition of Figure 6, a similar enlarged detail of the bead and wheelrim bead seat area with a :~ 25 side face applied to the t~re tread, the tyre bead fitting operation and the tyre bead removal operation.
. A third embodiment which~ i8 a 150/65 SR 320 radial .. ~ply tyre and wheel rim a~sembly is shown in cross-~ectional i~ . . ~ .
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1 ' ' ' ,:
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profile in Figure 11, a detailed half-section of the tyre is shown in Figure 12 and the wheel rim dimensions are to be described in relation to the wheel rim in cross-sectional prof ile of Figure 13.
A fourth embodiment is a 150/65 SR 320 ~Denovo' ~Registered Trade Mark) run-fl.at type tyre and wheel rim assembly. Figure 14 is a detailed half-section of the tyre and the wheel rim profile is again to be described with reference to Figure 13.
~ 10 A fifth embodiment is a 240~65 395 radial ply tyre - wheel rim assembly the cross-sectional profile of which is `` shown in Figure 15, a detailed half-cross-section of the .
~: tyre is shown in Figure 16 and the wheel rim is to be described with reference ~o Figure 13.
.. 15 A sixth embodiment is a 240/65 395 'Denovo' : (Registered Trade Mark) run-flat type tyre and wheel rim assembly shown in cross-sectional profile in Figure 17.
A detailed half-section of the tyre is shown in Figure 18 and again the wheel rim is to be described with reference to Figure 13.
A seventh embodiment, a 200/50-395 radial ply tyre and wheel rim assembly, is shown in cross-sec~ional profile : in Figure 19, a detailed cross-section of the tyre is shown in Figure 20 and the wheel rim i5 to be described : 25 with reference to Figure 13.
~ An eighth embodiment is a 560 x 13 tubeless cross-i ply tyre/wheel rim assembly shown in cross-section in ~ Figure 21. The wheel rim of this embodiment is to be ,.~ .
.. , ~ '1 , ` :
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: , described with reference to Figure 13.
E'igure 22 shows in cross-section an alternative known wheel rim having a substantially straight portion outwardly of the normal flange face.
The sixth embodiment is a radial ply tyre mounted upon the wheel rim of Figure 22 and Figure 23 shows the assembly in cross-section.
; Figure 24 is a cross-section of a tenth embodiment which is a run-flat 'Denovo' (Registered Trade Mark) tyre mounted upon the wheel rim of Figure 22. ' .
Figure 25 is a cross section ~f a final described embodiment which is an alternative radial ply tyre known in the art to that of Figure 23 having a construction '. particularly adapted to suit the wheel rim of Figure 22.
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The embodiment of Figure 1 i9 a 180 65 SR 340 radial ply tyre with a steel breaker and fitted to a 110 mm wide wheel rim having a diameter of 342 mm.
As shown in Figure 2 the tyre has a single radial carcass ply 1 of rayon and a breaker comprising two cut steel plies 2,3 which are at 18 to either side of the mid-circumferential plane of the tyre. The first ply 2 has an axial width of 126 mm. Each tyre bead wire 4 comprises a 6 x 6 (strands x turnsj of 0.038" diameter steel rubber ~ ;
coated. An apex strip 5 is positioned above each bead and - has a length of 30 mm and is made from rubber of 80 Shore hardness. A filler 6 of rubber coated nylon tyre fabric is positioned around the bead wire with khe nylon cords at 45 to the radial direction. A clinch strip 7 of rubber material i9 positioned in the outer part of the bead and extends to a radial height of 42 mm. An additional strip 8 of hard rubber material is positioned radially and axially inwards of the ` bead wire to form a toe 10. A toe reinforcement strip 9 of cro s-woven nylon fabric is positioned with the cords of the fabric at 45 to the radial direction so a~ to extend from the clinch strip 7 around the outer surface of the bead and the toe 10 a~ shown in Figure 2.
The tyre i9 cured using a clip ring shaped to the required toe shape shown in Figure 2 and the completed tyre has an extended toe of hard rubber incorporating a rein-forcement strip 9~ The toe has an axial length A* of 20 mm, an end width B* of 5 mm and a radial length C* of 6 mm.
The hard rubber material of the toe strip 8 has a ... . :
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n~minal hardness of 80 Shore. ~ :
The tyre assembly shown in Figure 3 is a 180 65 SR 340 I
'Denovo' (Registered Trade Mark) tyre mounted on a llO mm wide wheel rim. Such a tyre/wheel rim assembly is designed to be able to run deflated for substantial distances. :~
The tyre is shown in more detail i.n Figure 4 and comprises a single radial carcass ply ll of rayon and a breaker of two cut-steel plies 12,13 one at 18 to either - :
side of the mid-circumferential plane of the tyre. The inner steel breaker ply has a width of 126 mm. A high resilience rubber composition 14 is used in the shoulder and upper side wall portions of the tyre as described in ~n. ~ :
Patent ~o, ~64,971.
The tyre has a lubricant/sealant material coated on the inner surface of the tyre.in the region o the tyre crown which provides a sealant to reseal a puncture and a ~: lubricant to avoid internal damage and reduce heat build-up . when running flat. Further details of such a coating are given in Can. Patent Application ~o. 271,398 filed Feb. 2, 1977.
20 . The tyre lower sidewall and bead is constructed the ~.
same as that for Example l and in both cases the tyres are fitted to a llO mm wide wheel rim as shown in Figure 5. :~
., The wheel rim is rolled from .092" thick steel and the dimensions are as follows:- ~
- 25 A 110 mm i:
L 21 mm Q 41 mm ~ .
V 29.5 mm ', ~' ;,.
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p 20 mm U 37 mm B 12 mm H 13 mm T 5 mm Dl ~l40 mm G 12 mm D 342 mm Rg 7 mm rad R4 6 mm rad R5 4 mm rad R8 5 mm rad max R7 3 mm rad T 5 mm W 5 + 1 11 9 mm rad The above described tyre/wheel assemblies are suitable ~- for a vehicle having an axle load of 1840 lbs.
Figures 6-10 relate to the operation of the bead lock and will be described later.
The tyre/wheel rim assembly of Figure 11 i,s a smaller tyrejwheel assembly being a 150/65 SR 320 radial ply tyre fitted to a 95 mm wide rim.
The rim dimensions are as follows~
` 25 A 95 mm B 12 mm 1 318 mm D2 320 mm _ . . .
:
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~081282 G 12 ~
P 18 mm H 13 mm L 20 mm ; 5 Q 37.5 mm T 5 mm U 27 mm V 27 mm R4 6 ~m 10R5 4 mm ~; 7 3 mm R8 5 mm Rg 7 mm W 5 + 1 ~ 15 The material thickness is .092".
`i The radial ply tvre shown in Figure 12 comprises a ' ! single radial carcass ply 1 of rayon and a breaker comprising I two cut-stael plies 2,3 which are at 18 to either side of the ~-i mid-circumferential plane of the tyre. The first ply 2 has ~ ?
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:? 20 an axial width of 96 mm.
The bead wire 4 comprises a 5 x 4 (strands x turns) of .038 diameter steel wixe rubber coated. An apex strip 5 made from hard rubber compound as above is positioned above the bead and has a length of 25 mm. A filler pl~ 6 of rubber coated ~
-, 25 weftless nylon fanric is positioned over the bead wires with ~ ~' the n~vlon cords at 45 to the radial direction and a clinch `
strip 7 of hard rubber is positioned outwardly overlapping ~"'? the apex strip 5 and extends to a radial height of 36 mm.
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An additional strip of 80 Shore hardness rubber compound is used to form the toe 10 and a toe reinforcement strip of cross-woven nylon fabric to the same specification as the first example is positioned to form the outer toe surface. The toe construction is the same as in the first example except that the axial toe length A* in this case is 18 mm whereas in the first example A* was 20 mm.
The tyre shown in Figure 14 is a run flat 'Denovo' (Registexed Trade Mark) type of tyre of the same overall 150 65 SR 320 dimensions as the tyre in Figure 2. It is fitted to the same rim as the tyre of Figure 12. The tyre differs from the radial tyre in that the sidewalls are thickened and include a high resilience rubber compound 14 in the shoulder.
A lubricant sealant layer is utilised for run-flat perormance.
Both these features are the 9ame a9 for the second embodiment.
The tyres of Figures 10-14 are suitable for small cars having an axle load of 1280 lbs.
The tyre/wheel assembly of Figure 15 is a 240/65 - 395 ~i 20 radial ply tyre fitted to a 395 mm diameter rim. The tyre constructional dekails are shown in Figure 16 and the rim ~, dimensions, U9 ing the same nomenclature as Figure 13 are as follows:-A 170 mm B 12 mm :! Dl 393 mm ~` D2 395 mm G 13 mm : , . . ~ .. :
z p 20 mm H 14 mm ;
L 21 mm 47 mm T 7 mm ` U 50 mm v 33.5 mm ~
R4 8 mm -~ -R5 5 mm R7 5 mm ~ ~8 8 mm ,., W ' + 1 ''" .
The material thickness is .144".
, The tyre comprises a two ply radial casing 50 of rayon ;~ 15 and two folded edge steel breaker plies 51. The tyre beads :.. 1 : '' , ~
i 54 each comprise a 6 x 6 (strands x turns) winding of steel ~ wires having a diameter o~ .038" coated with rubber. An apex ~
`! strip 55 of 80 Shore hardness rubber i~ provided having a ~ ;
length of 42 ~m. ~A filler ply 56 of rubber coated nylon ' 20 fabric is positioned around the bead wire and eztends to a i~
I radial height of 42 mm on the inside of the bead and 28 mm on the outside of the bead. The two carcas~ plies 50 are arranged around the bead assembly in the usual manner and a climch strip 57 of 80 Shore hardness rubber compound is ~J ~ ~
posi~ioned outwardly of and overlapping the apex strip 55 so as to extend to a radial height oE 48 mm. :t' The toe 60 is formed from a strip 58 of 80, Shore ~ hardness rubber compound and a toe reinforcement strip 59 of !
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cross-woven nylon material as used in th~ first example i~
positioned around the outer s~rface o the toe and bead as shown. The finished tyre has the shape shown in Figure 16 and the axial toe length A* ln this case is 20 mm as in the , flrst embodiment.
The tyre and wheel assembly of E'igure 17 is a 240/65 -395 'Denovo' (Registered Trade Mark) type tyre fitted to a 395 mm diameter wheel rim. The tyre construction is ~hown in Figure 18 and its overall dime~nsions are the same as the tyre of Figure 16. The wheel rim is also the same as that described for the embodiment of Figures 15 and 16. The tyre structure is basically the same as that of the tyre of Figure . 16 except that the sidewalls are thickened by a layer 61 of . high resilience rubber. The details of the reinforcement material are the same as for the first example but in this ~: case the material is 15 mm thick from the carcass ply in the :. tyre shoulder, lO mm thick in the mid-sidewall region and tapers to the carcass under the breaker and at the apex strip as shown. The outer sidewall and clinch strip 57 are also thicker than in the radial tyre of Figure 16 the sidewall ~ :.
. rubber being 8 mm thick in the mid-sidewall region.
i The tyre/wheel assemblies of Figures 15-18 are . suitable for a vehicle having an axle load of 3200 lbs.
The above described examples are all 65 series tyres ~;
i~.e. each have an aspect ratio o 65%. The invention has ~.
.~ also been applied to other aspect ratio radial. tyres and the embodiments of Figures 19 and 20 is a 50 series radial ply :.
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tyre having dimensions of 200/50 - 395 and which is fitted ' ;" ~
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to a 395 mm diameter wheel rim having the same dimensi~ns as the embodiments of Figures 15~18.
The tyre has a two-ply rayon carcass 61 and two folded ply steel breakers 62 having a width of 150 mm. The bead area is the same as that of Fig~res 15-18 in relation to construction, dimensions and materials. ~;
:...... , i The invention has also been applied to a cross-ply tyre one example of which, shown in Figure 21, is a 560/13 tubeless tyre which i5 mounted on the same tyre rim section ;
as the third embodiment i.e. a 110 mm wide wheel rim but with a diameter of 13". The tyre carcass comprises two plies 63,64 of rayon.
The beads in cross-section are dimensionally the same as the first embodiment and compri9e 6 x 6 (strands x turns) of .038" diameter rubber coated steel wire. An apex strip 90 of 80 Shore hardneæs xubber material extends to a length of 30 mm and a clinch strip 91 of 80 Shore hardness rubber ;~
compound extending to a radial height of 42 mm i~ positioned in the outer regions of the bead. The bead toe 93 includes a reinforcement strip oi cros~-woven material exactly the same as the irst embodlment.
Another known car tyre assembly uses a different rim profile to the above 9tandard radial, cross-p~y and 'Denovo~
run-flat types of tyre9. The rim is shown in Figure 22 and ~comprises at each edge a portion 71 which i5 substantially straight when viewed in cross-~ection a9 9hown, and which `I provides a flat surface which may contact a tyre fitted to the rim. The rim having thi9 feature i9 modified according ~;
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to the present invention and thu~ the remainder of the rim comprises at each side flange 72 connecting the straight portion 71 to a bead seat region 73. Immediately inboard of the bead seat region 73 is formed a groove 74 which ~ 5 extends circumferentially around the rim, one groove 74 .~ being provided at either side o~ the rim. Between the two grooves 74 is provided a well 75 for tyre fitting in the usual manner. Typical rim dimensions are as ~ollows:-: A 125 mm : 10 B 17.6 mm U ~2 mm L 29 mm :: 40 mm V 29.8 mm . P 20 mm G 13.5 mm ... ..
D 395 mm Dl 393 mm ~: T 5 mm H 13 mm ; X 5.7 mm :~
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R4 6 mm rad :. 25 .. ; R8 5 mm rad ~ .
R7 3 mm rad : : , R 4 mm rad :
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R12 7 mm rad : The tyre and wheel rim assembly shown in Figure 23 comprises a radial ply tyre ha.ving a steel breaker 76 and a textile carcass reinforcement 77 fitted to the rim of Figure 22. The tyre.is of the same construction as the first embodiment. The textile carcass reinforcement 77 ~;
follows the standard shape from the mid-sidewall region to the bead region.i.e. the initi.al poxtion A of the ~extile lo carcass reinforcement 77 is convex and the second portion B
of the textile carcass reinforcement is concave (both when considered from the outside of the tyre). The tyre has an ..
outer bead profile to correspond with the wheel rim and in ; ``
particular to 'the straight portions 71 so that the tyre ..
then matches the wheel rim as shown. Each tyre bead includes a bead wire 78 and an extended toe 79 which is - `:
formed from hard rubber material (for.example 70-90 Shore).
The toe shape is such that the assembled tyre and wheel is .
ij as shown in Figure 23 and the toe is the same as that .
described for the first embodiment.
; The tyre and wheel rim a~sembly shown in Figure 24 . is a run-flat version of the tyre shown in Figure 23 and .
. comprises a single radial carcass ply 80 of rayon and a breaker 81 of two cut-steel ~lies. The tyre is of the same :
construction as the second embodiment and the tyre beads are constructed as described to provide the required toe ;` 79 to engage the grooves 74 in the rim~ Once again the ~ outer profile of the tyre in the region of the bead and ;
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lower sidewall i9 moulded so t.hat the tyre again matches the wheel rim as shown in Figure 24 as described in the previous embodlment.
The assembly shown in Figure 25 comprises a tyre :
: 5 which has a ratio of height tc width less than l.0, in this case 0.65 and a carcass reinforcement having a neutral fibre that follows, at least between the mid-height of each of the :
sidewalls and their respective bead wire, the natural equilibrium curve of a single ply caxcass having no breaker when such a carcass is subjected to inflation pressure. The curve is tangential to the bead rings, passes throùgh the . .
`. edges of the breaker and passes through the points in the ; sidewalls at which tangents drawn to the reinorcement are per~endicular to the tyre axis.
The tyre comprises a caxcass reinorcement ply 82 which is folded around each tyre bead wire 83,84 and a :
~ breaker structure 85 to reinforce the tread region. The ; carcass ply 82 in the lower sidewall zone is shaped to ., : ' . remain con~ex when viewed from outside the tyre until it ::~ ~ .
becomes a tangent to the bead wire 83. Thus the reinorce- .
.. .ment ply is con.vex.. throughout the ~one indicated C. Above the lower sidewall zone C the carcass ply 82 follows the ..... :
., ". ~, neutral equilibrium curve reerred to until in the shoulder '` zone 86 it is blended to curve smoothly to become a tangent :
.:: 25 to the breaker structure 85 as shown. .~
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. C is particularly shaped so as to be substantially parallel :: to the straight portion of the wheel rim 81. Further :
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According to the present invention, however, the lower bead region 87 is shaped the same as in the first embodiment so as to provide a toe 79 which engages the circumferentially extending groove 74 in the wheel rim to provide a bead lock according to the present invention. ~;
As published in U.S. Patent No. 3,910,336 are property of this type of tyre is that the tyre character-istics may be modi~ied by changing the xim width for a given tyre width. This may be done as long as the flange, -~
bead seat and circumferential groove shapes are maintained as shown without impairing the bead locking.
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lZ1~2 The oper~tion of the invention will now be described with reference to the ir~t embodiment. The discus~ion is ~or the tyre section in the ground contact area. The bead toe 10 is longer in the radial direction than the groove depth (6 and 5 mm respectively, see Figures 2 and 5) and thus when assembled by the method which will be de cribed later ; the toe 10 is under a degree of precompression between the -" groove 15 in the wheel rim and the bead wire 4. The tyre is retained on the wheel rim by the normal bead wire ten~ion force applied to the bead seat and the tyre/wheel rim assembl~
may be run inflated as normal.
Figure 6 shows the tyre and wheel assembly of Figure 1 in the tyre/ground contact area deflated but with no side force applied. In a cornering or turning manoeuvre a side force SF is developed increasing in intensity as the lateral acceleration increases. This side force distort~ the tyre sideways relative to the rim and causes the outboard bead to rotate. As a toe is provided according to the pre~ent invention, the centre of rotation of the bead i9 the end 10 of the bead toe which i8 located axially and radially in the groove 15 formed in the wheel rim and thus the moment is SF x Xl where Xl is the distance measured radially from the tread contact area to the centre of rotation.
The tyre bead is retained against this rotation by the moment of the bead wire ten~ion about the ~ame centre of bead rotation = Tl x X2 where X2 = the axial distance of the bead wire from the centre of rotation. It ~hould be noted that there i9 no retention force due to air pre~ure as the ' : . '' ': ' ~ ~3 ' . .
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:~08~ 82 tyre is being considered in the deflated condition.
Figure 7 shows on an enlarged qcale the forces applied - -to the outboard bead seat on the onset of bead rotation. In the condition shown the fitted bead tension Tl which pre-compresses the rubber in the area under the bead wire is sufficient to retain the bead on its seat by frictional grip, any moment due to the precompression force in the toe then being small. ~;
Increased side force generates an increased moment ~`
SF x Xl. This initiates the bead rotation and the bead wire 4 begins to move in the direction I inwardly of the wheel rim.
Th~ bead wire 4 is a substantially inextensible hoop around the ~ wheel rim and thus cannot follow the required circular locus to `~ rotate about the centre of rotation. Thus the bead wire 4 rotates and moves axially inwards to the position shown in ~ Figure 8. The complete toe of the tyre, which has an -, effective length Dl in Figure 7 i8 therefore compressed to -, a ~maller effective length D2 in Figure 8 which shows the position when the tyre is subjected to a degree of side force.
~, 20 The toe is substantially rigid in the direction o~ its effective length being made from hard rubber and having a reinforcement ply and being dimensioned to have a substantial compression 9tiffness or form stiffness along its length.
The reaction forces have a resultant force F3 generated by ~ 25 the toe against the bead wire 4 which has an axially outward `,, component F4 and a radially,outward component F5. The force ' F5 greatly increases the ten~ion in the bead wire 4. The latter tension adds to the tension force Tl an additional .'"`; - .
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:1~8~LZ82 component T2. Thu~ the retaining moment Tl x X2 is increased to T1 X3 + T2 X3 and rotation of the bead section has occurred about the centre of rotation to provide a balanced force condition and no further bead movement.
The above force balance occurs in the ground contact area only where the high side force is in fact applied to the tyre by the ground. How~ver, the increased bead wire tension affects the complete hoop of the bead wire 4 and tightens it onto the rim.~ This increases the grip of the tyre bead to the bead seat of the wheel rim. Bead rotation in the ground contact ~
area may be of the order of 90 when considered as the angle of ~;
f rotation of the normal bead ~eating portion 18-1a of the bead.
The bead toe between the bead wire 4 and the groove 15 may be given the required form stiffne~s by various means apart from the construction descxibed. It may for example be made entirely from hard rubber composition or other elastomeric compositions and it has been shown that a toe of the same shape but made of rubher having a hardness o~ greater than 80 Shore gives a ~atisfactory bead lock. The composition may include known additives for providing the required properties for example fibrous reinforcements which may be linearly or , randomly orientated.
`~ The toe may have more than one reinforcement ply 9 and/or in addition the reinforcement ply may comprise separate sections of fabric. The fabric may be woven, non-woven or knitted and made from various reinforcement ; materials known in the art. The fabric of the reinforcement ply 9 is selected for two purposes, firstly to prevent bulging ': ~
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~1~81Z82 of the toe and thus contributing to the ~orm stiffness when the toe is under lengthwise compression, and secondly to assist fitting as will be described. It ~hould be noted that the toe ~aterials are not under any substantial load except in the side force conditions which occur when steering of the vehicle is effected with the tyre deflated or substantially deflated.
The toe end 10 must be radially and axially inwards of the bead coil 4, so that it comes under increasing compression when the bead is subjected to a rotational moment as described. The moment applied by the ide force to the outboard bead may be increased in the ground contact area so as to generate the maximum increased compression and the greatest bead wire tension. The moment may be increased by using a stiffer lower sidewall area for example by a larger bead apex 5 than in conventional tyres and ~uch a stifened apex is used in the examples. B~ lower sidewall is meant the sidewall between the bead wire and a horizontal line drawn through the widest portion of the tyre when ), 20 inflated to normal inflation pre~sure and unloaded.
The shape of the end 10 of the toe is not critical although the flat-ended construction shown in the Figures showing tyre3 i9 conveniently manufactured u9ing a modiied clip ring and using the moulding diaphragm to form the inner curved toe surace. When a~sembled to the rim the centre of pressure between the toe end and the groove moves around the base of the groove 15 so that the toe does not readil~
buckle when the bead is rotated by the side force. Thus the : ' .
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preferred groove shape has a radiu~ed based a~ ~hown although other shapes may be utilised.
The wheel rim may be rolled by the conventional wheel ; manufacturing process.
The initial location or grip of the toe end 10 in the groove base 15 before rotation begins may be further improved b~ means of roughening the groove e.g. by knurling although with the above described embodiments this is not necessary.
Tyre fitting to ~he rim i9 conventional. The tyre may be fitted over the ~langes by hand tool~, normal service ~ ~
equipment, or automatic tyre fitting machinery. Upon inflation ~-. ~ :
the bead slides onto its seat ~nder the inflation pressure I.P.
as shown in Figure 9. The toe being made of elastomeric material is able to bend to the position shown and when the ~ :
; 15 bead reaches its fully home position on its bead seat 18-18 the toe is able to snap into the groove using the recovery `~
properties of the rubber of the toe in combination with the reinforcement ply 9 . When fully inflated the toe positively ., . ; -:
engages in the groove as shown in Figures 1 and 3 so that the toe end 10 is radially and axially located in the groove base 15 and the toe is under a degree of precompression between the groove and the bead wire 4.
To ensure correct fitting the straightened toe length -~ H measured from the heel point H.P.l to the toe end 10 must `~
.: 1 .
be less than the distance from the heel point H.P.2 of the rim along the bead seat 18-18 and to the nearest point on tha inboard face 19 of the groove 15 i.e. the length of the line H2.
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In the embodiments described to ensure tyre fitting the distance measured in the axial direction from the vertical part of the flange to the centre line of the groove must be at least the same as the axial distance from the end of the toe to the flange contacting vertical part of the bead beore the tyre is fitted. These dimensions are both 20 mm in the examples.
Tyre bead removal is shown in Figure 10. Conventional tyre removal tools comprise a spade ended tool 20 which is engaged between the wheel rim flange 21 and i8 then forced towards the centre of the tyre wheel assembly in the axial ` direction. The force does not produce any substantial bead ; rotation and the tyre bead can be successfully dislodged with the toe flexing sideways and without any damage to the tyre bead or toe.
The tyre wheel assemblies described above in relation to Figures 1 -5 were tested as the outer front wheel in a J
turn test (i.e. straight running followed by a full steering lock application) with the valve core removed. The test was repeated at successively higher speeds on a high grip tarmac~
surface. ~either of the embodiments dislodged at 40 mph which represents an applied side accele~ation of the order of 1 g.
Higher speeds do not apply greater side force to the tyre since under such conditions the vehicle slides. In Slalom testing at speeds in excess of 70 mph when the direction of the side force changed bead dislodgement did not occur. The ; assemblies were similarly proved on all other wheel positions.
Accordingly the assemblies were absolutely safe from . . .
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dislodgement at the maximum sideforce available even under extreme test conditions.
Even after the above tests the tyres were readily removed from the rims using a conventional hand-operated tyre demounting machine.
Filmed evidence of the tyre behaviour on the rim confirmed that the tyre bead moves in the ground contact area to lock the tyre to the wheel rim in the manner described. ~ :
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Different rim widths and tyre sizes have been tested successfully using bead locks to the present invention. In the case of different rim widths different material thicknesses may be required for wheel rim strength and to allow convenient rolling the groove dimensions are changed accordingly. The tyre toe dimensions are also changed in proportion and the invention operates precisely as in the detailed case described above.
The invention operates with different tyre section widths, aspect ratios and bead diameters and applies also to all other known tyre constructions tubed or tubeless including - radial ply tyres, belted bias tyres, cross-ply tyres and run-flat 'Denovo' (Registered Trade Mark) type tyres.
The bead lock is preerably applied to both tyre beads although it may be applied to only the inboard or outboard bead.
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This invention relates to wheel rims.
In conventional tyre and wheel rim assemblies the tyre beads are retained on their respective bead seats by means of the internal air pressure and frictional restraint due to the compression in the elastomer under the bead wire ; when fitted onto the tapered seat of the rim. Lowering the air pressure in the tyre, however, lessens the reten-tion force from internal air pressure and eventually at a sufficiently low internal pressure the assembly reaches an unsafe condition in which the tyre beads may be dis-, placed from their seats by sideways force such as is generated in an accident avoidance manoeuvre.
The European motor industry uses a variety of teststo check bead dislodgement. A typical test is carried out by testing a tyre and wheel rim assembly as the outer front wheel i.e. a left-hand or near side in a right-hand J turn test at 25 mph. The test comprises straight running at 25 mph and then the sudden application of full steering lock. The test is repeated at progressively reducing tyre inflation pressures until dislodgement occurs. Usually the pressure reduction steps are 2 psi. Typical production radial ply car tyres normally dislodge a bead at air pressures of the order of 5-15 psi in such a test.
Typical tubeless radial ply car tyres normally dislodge a bead at pressures of the order of 5-15 psi in such a test.
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Dislodgement of a tyre bead ~rom its seat a~fects vehicle control. In the use of wheels which include a well to allow tyre fitting there i5 generally a grave danger of complete separation of the tyre from its wheel rim.
In the use of a vehicle, cornering generates sideways forces which displace the tread laterally with respect to the wheel rim. These forces are transmitted by the tyre carcass to the tyre bead. In the region of the tyre adjacent to the ground contact area axial forces (i.e. in the direction of the tyre axis) and turning moments (i.e. about a circumferential line through the bead) are generated. In the absence of air pressure these forces may be sufficient to produce lifting of the heel of the bead thus reducing the frictional force between the bead base and the bead seat on the rim which, in said deflated state, is the only force which retains the bead on it~ seat. As a result the bead moves down its tapered bead seat laterally inwardly of the rim flange reducing the tension in the bead `~
wire and, very rapidly the residual bead retaining force becomes less than the dislodging forces and the bead leaves itB seat and ~a 119 into the well.
Previous attempts to solve this problem have centred around the use of wheel rims which do not have a well. The resultant flat-based rim obviates the danger of tyre wheel separation but has the disadva~tage that the tyre beads are usually able to move axially between the spaced-apart flanges.
Thus the sideways force which can be transmitted between the wheel and the ground changes suddenly from zero when a bead is moving across the rim to a maximum when both beads are ~ , : - ' ; :
: ' .. .. ..
- together against a ~l~nge. ~h10 may, in the extreme, cau~e lo~e o control of the vehiclel.
Thi~ i~ equally true for a well based rim h~ving a filling device, a wheel rim which ha~ a fitting well closed by crimping after tyre fitting or a divided wheel rim as~embl~.
A divided wheel rim y~tem require~ several extra components with consequent disadvantages in sealing the air chamber of the tyre, increased co~t, increa~ed weight and ~ increased complexity for servicing. The well illing ~ystem ~ 10 also increases the assembly weight, cost and complicates servicing even though a one-piece wheel rim may then be utilised. None of these previous attempts, however, - overcome the problems o side force transmission when a bead moves axially acro~s the rim.
Bead spacer rings which are rigid circumferentially ~ -... .
extending rings illing the space between the two beads have been propo~ed for u~e with divided whcel rims to hold both 'I beads in place, ~ee for example, U.K. Patent No. 222,768.
Such device~ provide the required properties but add yet another component to the already complex divided wheel rim as0embly .
Another modiication to a divided wheel rim having a flat base and no well i~ disclosed in U.K. Patent ~o.
1,395,714 in which a notch is formed between two wheel rim components at the outboard bead side of the flat base rim and an extended rubber toe is provided on the bead which rests freely in the notch. This assembly is still subject to all the complications of divided wheel rims including the _ . , .
~?13lZ8;~
air sealing problem and use~ a flat based wheel rim for safety in high side ~orce con~itions.
Yet another system i~ shown in U.K. Patent No.
890,959 where a divided wheel rim i9 proposed in which a fabric reinforced, rubber covered extension of the bead is clamped between the rim parts to seal the assembly. Whilst this may retain the bead, effective sealing depends on accurate assembly and clamping of the bead extension.
The system is al~o still subject to the general dis-advantages of divided wheel rims.
One piece flat based wheel rims are known and one such assembly is disclosed in U.K. Patent ~o. 1,348,891 where a one-piece wheel rim has provided a well for tyre fitting which is subsequently closed by permanently crimping it closed so as to provide a flat based rim. Such an assembly has the further disadvantage of it being necessary to destroy the rim to repair the tyre or check the inside ~or damage.
Still another ~y~tem is to provide a well in the normal bead ~eat area at on~ aide of a flat ba~ed wheel rim ~ ;
and having ~itted the tyre over the flange~ u~ing thi~ well to pre~s both beads again~t ~he ~lange furthest from the well and insert a well filler which subse~uentl~ form~ the bead ~eat. Such a ~ystem ie di9closed in U.S. Patent No.
3,884j286.
Attempts to overcome the problems of bsad retention and yet allow the use o~ a normal well in a wheel rim have included small circumferentially extending humps formed in the rim adjacent to the bead. Such humps can be 1.7 mm-in ' ' ~'~,,, ' ' ' . ' . ' . I
106~1Z8;~
height relative to the bead seat toe diameter but, in any case, these must be limited to dimensions which permit a tyre to be fitted to its seats by inflation pressure without damage. The sideways forces generated by the road when the tyre is deflated greatly exceed the force generated by the inflation pressure and thus any hump which allows tyre fitting cannot prevent bead dislodgement and thus the tyre bead is able to enter the well.
One-piece wheel rims having radially movable stops adjacent to the bead seat are also known but here again to provide the necessary stop movement adds complication, cost and air sealing problems to the assembly.
More recently in U.S. Patent ~o. 3,951,192 it has been proposed to provide hook-like extensions ormed on the outer lower sidewall areas of the tyre and shaped to engage around the wheel rim flange so as to resist bead movement.
However, sideway9 ~orces rotate the bead with resulting heel li~ting and thus this construction cannot, in our experience, be satisfactory. In addition they are subject to the like-lihood o~ damage rom kerbstones.
~hus all known previou~ attempts to provide or posi~ive bead retention and thus the ability to control a vehicle even when a tyre is deflated have either not provided a solution or have been complex and thexefore too costly.
The automobile industry currently fits tyres to rims automatically using irstly a machine which rolls both beads over one flange using the well to give the necessary clearance ~ and secondly a so-called 'explosion' inflation device which :- .
, '............... ` ' ' ' almost instantaneously inflates the tyre and forces the beads onto their respective bead seats. This means that the industry requ~res tyre and wheel rims compatible with this machinery~
We have investigated the phenomena of the forces involved in dislodging the beads of a tyre from a wheel rim when on a vehicle. We have also investigated the phenomena of the forces involved in fitting tyres to and removing tyres from wheel rims. We have ound that the road generated forces involved in tyre bsad dislodgement are quite different from the forces involved in the removal of a tyre from the wheel rim with the wheel tyre as~embly removed from the vehicle for tyre replacement or repair.
Accordingly we have utilised the difference between the road generated dislodgement force~ and the tyre removal force~ to provide a bead lock which obviate~ the above problems i~
and allow3 for khe ~afe use of a one-piece wheel rim.
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According to one aspect of the present invention, a one-piece wheel rim for a tubeless pneumatic tyre wherein the radially outer profile of the wheel rim considered in a plane containing the axis of the wheel rim comprises, in se~uence, from one edge of the wheel rim profile:- a radially extending bead retaining flange having a radially outer edge which is turned axially outwardly; a curved seating portion for the heel of a tyre bead; a substantially straight main bead seating portion which tapers radially inwardly towards the axially inner regions of the wheel rim; an open bead toe locating groove immediately adjacent to said bead seating portion formed by, again in sequence:- a radially inwardly curving axially outer groove edge portion having a radius in the range of 5mm to 8mm; an outwardly concave groove base portion : having a radius in the range of 3mm to 5mm; and a radially in-wardly curving axially inner groove edge portion having a radius in the range of 5mm to 8mm; a substantially straight flat ledge portion; a central tyre-fitting well portion having a diameter substantially smaller than the main bead seating portion and arranged to allow tyre fitting over the tyre re-taining flange: a second open bead toe locating groove formed by, again in sequence:- a radially inwardly curving axially inner groove edge portion having a radius in the range of 5mm to 8mm;
: an outwardly concave groove base portion having a radius in the range of 3mm to 5mm; and a radially inwardly curving axially outer groove edge portion having a radius in the range of 5mm to 8mm; a substantially straight main bead seating portion which tapers radially inwardly towards the axially inner regions of the wheel rim; and a radially extending bead retaining flange having a radially outer edge which is ~urned axially outwardly.
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Several embodiment~ of the present invention will now be described, by way of example only, to ~how the ~co~e of application of the present invention~ The embodiments will each be described in conjunction with diagrammatic drawings which relate to each embodiment as $ollows:-The first embodiment is a 180 65 SR 340 radial tyre and wheel rim assembly. A cross-sectional profile of the assembly is shown in Fiyure 1, a detailed half-section of the tyre is shown in Figure 2 and the rim is shown in ;~10 detailed cross-section in Figure S.
The second embodiment is a 180 65 SR 340 'Denovo' (Registered ~rade ~ark) run-flat type of tyre/wheel rim a~sembly and a cross-sectional profile of the assembly is shown in Figure 3 a detailed half-section of the tyre is -15 shown in Figure 4 and the wheel rim is shown in detailed ,, ~ .
cross-section in Figure 5.
Figures 6, 7, 8, 9, and 10 are shown to assist in ;-the following description of the operation o the invention based on the current understanding of said i~vention and , . ..
;20 show respectively a cross-section of a t~re and wheel rim assembly in the ground-contacting area running deflated, an eniarged detail of the bead and wheel rim bead seat area in the condition of Figure 6, a similar enlarged detail of the bead and wheelrim bead seat area with a :~ 25 side face applied to the t~re tread, the tyre bead fitting operation and the tyre bead removal operation.
. A third embodiment which~ i8 a 150/65 SR 320 radial .. ~ply tyre and wheel rim a~sembly is shown in cross-~ectional i~ . . ~ .
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profile in Figure 11, a detailed half-section of the tyre is shown in Figure 12 and the wheel rim dimensions are to be described in relation to the wheel rim in cross-sectional prof ile of Figure 13.
A fourth embodiment is a 150/65 SR 320 ~Denovo' ~Registered Trade Mark) run-fl.at type tyre and wheel rim assembly. Figure 14 is a detailed half-section of the tyre and the wheel rim profile is again to be described with reference to Figure 13.
~ 10 A fifth embodiment is a 240~65 395 radial ply tyre - wheel rim assembly the cross-sectional profile of which is `` shown in Figure 15, a detailed half-cross-section of the .
~: tyre is shown in Figure 16 and the wheel rim is to be described with reference ~o Figure 13.
.. 15 A sixth embodiment is a 240/65 395 'Denovo' : (Registered Trade Mark) run-flat type tyre and wheel rim assembly shown in cross-sectional profile in Figure 17.
A detailed half-section of the tyre is shown in Figure 18 and again the wheel rim is to be described with reference to Figure 13.
A seventh embodiment, a 200/50-395 radial ply tyre and wheel rim assembly, is shown in cross-sec~ional profile : in Figure 19, a detailed cross-section of the tyre is shown in Figure 20 and the wheel rim i5 to be described : 25 with reference to Figure 13.
~ An eighth embodiment is a 560 x 13 tubeless cross-i ply tyre/wheel rim assembly shown in cross-section in ~ Figure 21. The wheel rim of this embodiment is to be ,.~ .
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: , described with reference to Figure 13.
E'igure 22 shows in cross-section an alternative known wheel rim having a substantially straight portion outwardly of the normal flange face.
The sixth embodiment is a radial ply tyre mounted upon the wheel rim of Figure 22 and Figure 23 shows the assembly in cross-section.
; Figure 24 is a cross-section of a tenth embodiment which is a run-flat 'Denovo' (Registered Trade Mark) tyre mounted upon the wheel rim of Figure 22. ' .
Figure 25 is a cross section ~f a final described embodiment which is an alternative radial ply tyre known in the art to that of Figure 23 having a construction '. particularly adapted to suit the wheel rim of Figure 22.
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The embodiment of Figure 1 i9 a 180 65 SR 340 radial ply tyre with a steel breaker and fitted to a 110 mm wide wheel rim having a diameter of 342 mm.
As shown in Figure 2 the tyre has a single radial carcass ply 1 of rayon and a breaker comprising two cut steel plies 2,3 which are at 18 to either side of the mid-circumferential plane of the tyre. The first ply 2 has an axial width of 126 mm. Each tyre bead wire 4 comprises a 6 x 6 (strands x turnsj of 0.038" diameter steel rubber ~ ;
coated. An apex strip 5 is positioned above each bead and - has a length of 30 mm and is made from rubber of 80 Shore hardness. A filler 6 of rubber coated nylon tyre fabric is positioned around the bead wire with khe nylon cords at 45 to the radial direction. A clinch strip 7 of rubber material i9 positioned in the outer part of the bead and extends to a radial height of 42 mm. An additional strip 8 of hard rubber material is positioned radially and axially inwards of the ` bead wire to form a toe 10. A toe reinforcement strip 9 of cro s-woven nylon fabric is positioned with the cords of the fabric at 45 to the radial direction so a~ to extend from the clinch strip 7 around the outer surface of the bead and the toe 10 a~ shown in Figure 2.
The tyre i9 cured using a clip ring shaped to the required toe shape shown in Figure 2 and the completed tyre has an extended toe of hard rubber incorporating a rein-forcement strip 9~ The toe has an axial length A* of 20 mm, an end width B* of 5 mm and a radial length C* of 6 mm.
The hard rubber material of the toe strip 8 has a ... . :
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n~minal hardness of 80 Shore. ~ :
The tyre assembly shown in Figure 3 is a 180 65 SR 340 I
'Denovo' (Registered Trade Mark) tyre mounted on a llO mm wide wheel rim. Such a tyre/wheel rim assembly is designed to be able to run deflated for substantial distances. :~
The tyre is shown in more detail i.n Figure 4 and comprises a single radial carcass ply ll of rayon and a breaker of two cut-steel plies 12,13 one at 18 to either - :
side of the mid-circumferential plane of the tyre. The inner steel breaker ply has a width of 126 mm. A high resilience rubber composition 14 is used in the shoulder and upper side wall portions of the tyre as described in ~n. ~ :
Patent ~o, ~64,971.
The tyre has a lubricant/sealant material coated on the inner surface of the tyre.in the region o the tyre crown which provides a sealant to reseal a puncture and a ~: lubricant to avoid internal damage and reduce heat build-up . when running flat. Further details of such a coating are given in Can. Patent Application ~o. 271,398 filed Feb. 2, 1977.
20 . The tyre lower sidewall and bead is constructed the ~.
same as that for Example l and in both cases the tyres are fitted to a llO mm wide wheel rim as shown in Figure 5. :~
., The wheel rim is rolled from .092" thick steel and the dimensions are as follows:- ~
- 25 A 110 mm i:
L 21 mm Q 41 mm ~ .
V 29.5 mm ', ~' ;,.
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. .
p 20 mm U 37 mm B 12 mm H 13 mm T 5 mm Dl ~l40 mm G 12 mm D 342 mm Rg 7 mm rad R4 6 mm rad R5 4 mm rad R8 5 mm rad max R7 3 mm rad T 5 mm W 5 + 1 11 9 mm rad The above described tyre/wheel assemblies are suitable ~- for a vehicle having an axle load of 1840 lbs.
Figures 6-10 relate to the operation of the bead lock and will be described later.
The tyre/wheel rim assembly of Figure 11 i,s a smaller tyrejwheel assembly being a 150/65 SR 320 radial ply tyre fitted to a 95 mm wide rim.
The rim dimensions are as follows~
` 25 A 95 mm B 12 mm 1 318 mm D2 320 mm _ . . .
:
.
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P 18 mm H 13 mm L 20 mm ; 5 Q 37.5 mm T 5 mm U 27 mm V 27 mm R4 6 ~m 10R5 4 mm ~; 7 3 mm R8 5 mm Rg 7 mm W 5 + 1 ~ 15 The material thickness is .092".
`i The radial ply tvre shown in Figure 12 comprises a ' ! single radial carcass ply 1 of rayon and a breaker comprising I two cut-stael plies 2,3 which are at 18 to either side of the ~-i mid-circumferential plane of the tyre. The first ply 2 has ~ ?
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:? 20 an axial width of 96 mm.
The bead wire 4 comprises a 5 x 4 (strands x turns) of .038 diameter steel wixe rubber coated. An apex strip 5 made from hard rubber compound as above is positioned above the bead and has a length of 25 mm. A filler pl~ 6 of rubber coated ~
-, 25 weftless nylon fanric is positioned over the bead wires with ~ ~' the n~vlon cords at 45 to the radial direction and a clinch `
strip 7 of hard rubber is positioned outwardly overlapping ~"'? the apex strip 5 and extends to a radial height of 36 mm.
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An additional strip of 80 Shore hardness rubber compound is used to form the toe 10 and a toe reinforcement strip of cross-woven nylon fabric to the same specification as the first example is positioned to form the outer toe surface. The toe construction is the same as in the first example except that the axial toe length A* in this case is 18 mm whereas in the first example A* was 20 mm.
The tyre shown in Figure 14 is a run flat 'Denovo' (Registexed Trade Mark) type of tyre of the same overall 150 65 SR 320 dimensions as the tyre in Figure 2. It is fitted to the same rim as the tyre of Figure 12. The tyre differs from the radial tyre in that the sidewalls are thickened and include a high resilience rubber compound 14 in the shoulder.
A lubricant sealant layer is utilised for run-flat perormance.
Both these features are the 9ame a9 for the second embodiment.
The tyres of Figures 10-14 are suitable for small cars having an axle load of 1280 lbs.
The tyre/wheel assembly of Figure 15 is a 240/65 - 395 ~i 20 radial ply tyre fitted to a 395 mm diameter rim. The tyre constructional dekails are shown in Figure 16 and the rim ~, dimensions, U9 ing the same nomenclature as Figure 13 are as follows:-A 170 mm B 12 mm :! Dl 393 mm ~` D2 395 mm G 13 mm : , . . ~ .. :
z p 20 mm H 14 mm ;
L 21 mm 47 mm T 7 mm ` U 50 mm v 33.5 mm ~
R4 8 mm -~ -R5 5 mm R7 5 mm ~ ~8 8 mm ,., W ' + 1 ''" .
The material thickness is .144".
, The tyre comprises a two ply radial casing 50 of rayon ;~ 15 and two folded edge steel breaker plies 51. The tyre beads :.. 1 : '' , ~
i 54 each comprise a 6 x 6 (strands x turns) winding of steel ~ wires having a diameter o~ .038" coated with rubber. An apex ~
`! strip 55 of 80 Shore hardness rubber i~ provided having a ~ ;
length of 42 ~m. ~A filler ply 56 of rubber coated nylon ' 20 fabric is positioned around the bead wire and eztends to a i~
I radial height of 42 mm on the inside of the bead and 28 mm on the outside of the bead. The two carcas~ plies 50 are arranged around the bead assembly in the usual manner and a climch strip 57 of 80 Shore hardness rubber compound is ~J ~ ~
posi~ioned outwardly of and overlapping the apex strip 55 so as to extend to a radial height oE 48 mm. :t' The toe 60 is formed from a strip 58 of 80, Shore ~ hardness rubber compound and a toe reinforcement strip 59 of !
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cross-woven nylon material as used in th~ first example i~
positioned around the outer s~rface o the toe and bead as shown. The finished tyre has the shape shown in Figure 16 and the axial toe length A* ln this case is 20 mm as in the , flrst embodiment.
The tyre and wheel assembly of E'igure 17 is a 240/65 -395 'Denovo' (Registered Trade Mark) type tyre fitted to a 395 mm diameter wheel rim. The tyre construction is ~hown in Figure 18 and its overall dime~nsions are the same as the tyre of Figure 16. The wheel rim is also the same as that described for the embodiment of Figures 15 and 16. The tyre structure is basically the same as that of the tyre of Figure . 16 except that the sidewalls are thickened by a layer 61 of . high resilience rubber. The details of the reinforcement material are the same as for the first example but in this ~: case the material is 15 mm thick from the carcass ply in the :. tyre shoulder, lO mm thick in the mid-sidewall region and tapers to the carcass under the breaker and at the apex strip as shown. The outer sidewall and clinch strip 57 are also thicker than in the radial tyre of Figure 16 the sidewall ~ :.
. rubber being 8 mm thick in the mid-sidewall region.
i The tyre/wheel assemblies of Figures 15-18 are . suitable for a vehicle having an axle load of 3200 lbs.
The above described examples are all 65 series tyres ~;
i~.e. each have an aspect ratio o 65%. The invention has ~.
.~ also been applied to other aspect ratio radial. tyres and the embodiments of Figures 19 and 20 is a 50 series radial ply :.
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tyre having dimensions of 200/50 - 395 and which is fitted ' ;" ~
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to a 395 mm diameter wheel rim having the same dimensi~ns as the embodiments of Figures 15~18.
The tyre has a two-ply rayon carcass 61 and two folded ply steel breakers 62 having a width of 150 mm. The bead area is the same as that of Fig~res 15-18 in relation to construction, dimensions and materials. ~;
:...... , i The invention has also been applied to a cross-ply tyre one example of which, shown in Figure 21, is a 560/13 tubeless tyre which i5 mounted on the same tyre rim section ;
as the third embodiment i.e. a 110 mm wide wheel rim but with a diameter of 13". The tyre carcass comprises two plies 63,64 of rayon.
The beads in cross-section are dimensionally the same as the first embodiment and compri9e 6 x 6 (strands x turns) of .038" diameter rubber coated steel wire. An apex strip 90 of 80 Shore hardneæs xubber material extends to a length of 30 mm and a clinch strip 91 of 80 Shore hardness rubber ;~
compound extending to a radial height of 42 mm i~ positioned in the outer regions of the bead. The bead toe 93 includes a reinforcement strip oi cros~-woven material exactly the same as the irst embodlment.
Another known car tyre assembly uses a different rim profile to the above 9tandard radial, cross-p~y and 'Denovo~
run-flat types of tyre9. The rim is shown in Figure 22 and ~comprises at each edge a portion 71 which i5 substantially straight when viewed in cross-~ection a9 9hown, and which `I provides a flat surface which may contact a tyre fitted to the rim. The rim having thi9 feature i9 modified according ~;
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to the present invention and thu~ the remainder of the rim comprises at each side flange 72 connecting the straight portion 71 to a bead seat region 73. Immediately inboard of the bead seat region 73 is formed a groove 74 which ~ 5 extends circumferentially around the rim, one groove 74 .~ being provided at either side o~ the rim. Between the two grooves 74 is provided a well 75 for tyre fitting in the usual manner. Typical rim dimensions are as ~ollows:-: A 125 mm : 10 B 17.6 mm U ~2 mm L 29 mm :: 40 mm V 29.8 mm . P 20 mm G 13.5 mm ... ..
D 395 mm Dl 393 mm ~: T 5 mm H 13 mm ; X 5.7 mm :~
~: W 5 ~ 1 . R5 4 mm rad ~ .
R4 6 mm rad :. 25 .. ; R8 5 mm rad ~ .
R7 3 mm rad : : , R 4 mm rad :
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R12 7 mm rad : The tyre and wheel rim assembly shown in Figure 23 comprises a radial ply tyre ha.ving a steel breaker 76 and a textile carcass reinforcement 77 fitted to the rim of Figure 22. The tyre.is of the same construction as the first embodiment. The textile carcass reinforcement 77 ~;
follows the standard shape from the mid-sidewall region to the bead region.i.e. the initi.al poxtion A of the ~extile lo carcass reinforcement 77 is convex and the second portion B
of the textile carcass reinforcement is concave (both when considered from the outside of the tyre). The tyre has an ..
outer bead profile to correspond with the wheel rim and in ; ``
particular to 'the straight portions 71 so that the tyre ..
then matches the wheel rim as shown. Each tyre bead includes a bead wire 78 and an extended toe 79 which is - `:
formed from hard rubber material (for.example 70-90 Shore).
The toe shape is such that the assembled tyre and wheel is .
ij as shown in Figure 23 and the toe is the same as that .
described for the first embodiment.
; The tyre and wheel rim a~sembly shown in Figure 24 . is a run-flat version of the tyre shown in Figure 23 and .
. comprises a single radial carcass ply 80 of rayon and a breaker 81 of two cut-steel ~lies. The tyre is of the same :
construction as the second embodiment and the tyre beads are constructed as described to provide the required toe ;` 79 to engage the grooves 74 in the rim~ Once again the ~ outer profile of the tyre in the region of the bead and ;
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lower sidewall i9 moulded so t.hat the tyre again matches the wheel rim as shown in Figure 24 as described in the previous embodlment.
The assembly shown in Figure 25 comprises a tyre :
: 5 which has a ratio of height tc width less than l.0, in this case 0.65 and a carcass reinforcement having a neutral fibre that follows, at least between the mid-height of each of the :
sidewalls and their respective bead wire, the natural equilibrium curve of a single ply caxcass having no breaker when such a carcass is subjected to inflation pressure. The curve is tangential to the bead rings, passes throùgh the . .
`. edges of the breaker and passes through the points in the ; sidewalls at which tangents drawn to the reinorcement are per~endicular to the tyre axis.
The tyre comprises a caxcass reinorcement ply 82 which is folded around each tyre bead wire 83,84 and a :
~ breaker structure 85 to reinforce the tread region. The ; carcass ply 82 in the lower sidewall zone is shaped to ., : ' . remain con~ex when viewed from outside the tyre until it ::~ ~ .
becomes a tangent to the bead wire 83. Thus the reinorce- .
.. .ment ply is con.vex.. throughout the ~one indicated C. Above the lower sidewall zone C the carcass ply 82 follows the ..... :
., ". ~, neutral equilibrium curve reerred to until in the shoulder '` zone 86 it is blended to curve smoothly to become a tangent :
.:: 25 to the breaker structure 85 as shown. .~
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.:` . The tyre carcass ply 82 in the lower sidewall zone ~ :
. C is particularly shaped so as to be substantially parallel :: to the straight portion of the wheel rim 81. Further :
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.. . ~ . . ~ . ` . .. : , , details of the tyre carcass are published in U.S. Patent Specification No. 3,910,336.
According to the present invention, however, the lower bead region 87 is shaped the same as in the first embodiment so as to provide a toe 79 which engages the circumferentially extending groove 74 in the wheel rim to provide a bead lock according to the present invention. ~;
As published in U.S. Patent No. 3,910,336 are property of this type of tyre is that the tyre character-istics may be modi~ied by changing the xim width for a given tyre width. This may be done as long as the flange, -~
bead seat and circumferential groove shapes are maintained as shown without impairing the bead locking.
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lZ1~2 The oper~tion of the invention will now be described with reference to the ir~t embodiment. The discus~ion is ~or the tyre section in the ground contact area. The bead toe 10 is longer in the radial direction than the groove depth (6 and 5 mm respectively, see Figures 2 and 5) and thus when assembled by the method which will be de cribed later ; the toe 10 is under a degree of precompression between the -" groove 15 in the wheel rim and the bead wire 4. The tyre is retained on the wheel rim by the normal bead wire ten~ion force applied to the bead seat and the tyre/wheel rim assembl~
may be run inflated as normal.
Figure 6 shows the tyre and wheel assembly of Figure 1 in the tyre/ground contact area deflated but with no side force applied. In a cornering or turning manoeuvre a side force SF is developed increasing in intensity as the lateral acceleration increases. This side force distort~ the tyre sideways relative to the rim and causes the outboard bead to rotate. As a toe is provided according to the pre~ent invention, the centre of rotation of the bead i9 the end 10 of the bead toe which i8 located axially and radially in the groove 15 formed in the wheel rim and thus the moment is SF x Xl where Xl is the distance measured radially from the tread contact area to the centre of rotation.
The tyre bead is retained against this rotation by the moment of the bead wire ten~ion about the ~ame centre of bead rotation = Tl x X2 where X2 = the axial distance of the bead wire from the centre of rotation. It ~hould be noted that there i9 no retention force due to air pre~ure as the ' : . '' ': ' ~ ~3 ' . .
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:~08~ 82 tyre is being considered in the deflated condition.
Figure 7 shows on an enlarged qcale the forces applied - -to the outboard bead seat on the onset of bead rotation. In the condition shown the fitted bead tension Tl which pre-compresses the rubber in the area under the bead wire is sufficient to retain the bead on its seat by frictional grip, any moment due to the precompression force in the toe then being small. ~;
Increased side force generates an increased moment ~`
SF x Xl. This initiates the bead rotation and the bead wire 4 begins to move in the direction I inwardly of the wheel rim.
Th~ bead wire 4 is a substantially inextensible hoop around the ~ wheel rim and thus cannot follow the required circular locus to `~ rotate about the centre of rotation. Thus the bead wire 4 rotates and moves axially inwards to the position shown in ~ Figure 8. The complete toe of the tyre, which has an -, effective length Dl in Figure 7 i8 therefore compressed to -, a ~maller effective length D2 in Figure 8 which shows the position when the tyre is subjected to a degree of side force.
~, 20 The toe is substantially rigid in the direction o~ its effective length being made from hard rubber and having a reinforcement ply and being dimensioned to have a substantial compression 9tiffness or form stiffness along its length.
The reaction forces have a resultant force F3 generated by ~ 25 the toe against the bead wire 4 which has an axially outward `,, component F4 and a radially,outward component F5. The force ' F5 greatly increases the ten~ion in the bead wire 4. The latter tension adds to the tension force Tl an additional .'"`; - .
A 1~-.` .' ' . . . . . j ....
:1~8~LZ82 component T2. Thu~ the retaining moment Tl x X2 is increased to T1 X3 + T2 X3 and rotation of the bead section has occurred about the centre of rotation to provide a balanced force condition and no further bead movement.
The above force balance occurs in the ground contact area only where the high side force is in fact applied to the tyre by the ground. How~ver, the increased bead wire tension affects the complete hoop of the bead wire 4 and tightens it onto the rim.~ This increases the grip of the tyre bead to the bead seat of the wheel rim. Bead rotation in the ground contact ~
area may be of the order of 90 when considered as the angle of ~;
f rotation of the normal bead ~eating portion 18-1a of the bead.
The bead toe between the bead wire 4 and the groove 15 may be given the required form stiffne~s by various means apart from the construction descxibed. It may for example be made entirely from hard rubber composition or other elastomeric compositions and it has been shown that a toe of the same shape but made of rubher having a hardness o~ greater than 80 Shore gives a ~atisfactory bead lock. The composition may include known additives for providing the required properties for example fibrous reinforcements which may be linearly or , randomly orientated.
`~ The toe may have more than one reinforcement ply 9 and/or in addition the reinforcement ply may comprise separate sections of fabric. The fabric may be woven, non-woven or knitted and made from various reinforcement ; materials known in the art. The fabric of the reinforcement ply 9 is selected for two purposes, firstly to prevent bulging ': ~
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~1~81Z82 of the toe and thus contributing to the ~orm stiffness when the toe is under lengthwise compression, and secondly to assist fitting as will be described. It ~hould be noted that the toe ~aterials are not under any substantial load except in the side force conditions which occur when steering of the vehicle is effected with the tyre deflated or substantially deflated.
The toe end 10 must be radially and axially inwards of the bead coil 4, so that it comes under increasing compression when the bead is subjected to a rotational moment as described. The moment applied by the ide force to the outboard bead may be increased in the ground contact area so as to generate the maximum increased compression and the greatest bead wire tension. The moment may be increased by using a stiffer lower sidewall area for example by a larger bead apex 5 than in conventional tyres and ~uch a stifened apex is used in the examples. B~ lower sidewall is meant the sidewall between the bead wire and a horizontal line drawn through the widest portion of the tyre when ), 20 inflated to normal inflation pre~sure and unloaded.
The shape of the end 10 of the toe is not critical although the flat-ended construction shown in the Figures showing tyre3 i9 conveniently manufactured u9ing a modiied clip ring and using the moulding diaphragm to form the inner curved toe surace. When a~sembled to the rim the centre of pressure between the toe end and the groove moves around the base of the groove 15 so that the toe does not readil~
buckle when the bead is rotated by the side force. Thus the : ' .
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preferred groove shape has a radiu~ed based a~ ~hown although other shapes may be utilised.
The wheel rim may be rolled by the conventional wheel ; manufacturing process.
The initial location or grip of the toe end 10 in the groove base 15 before rotation begins may be further improved b~ means of roughening the groove e.g. by knurling although with the above described embodiments this is not necessary.
Tyre fitting to ~he rim i9 conventional. The tyre may be fitted over the ~langes by hand tool~, normal service ~ ~
equipment, or automatic tyre fitting machinery. Upon inflation ~-. ~ :
the bead slides onto its seat ~nder the inflation pressure I.P.
as shown in Figure 9. The toe being made of elastomeric material is able to bend to the position shown and when the ~ :
; 15 bead reaches its fully home position on its bead seat 18-18 the toe is able to snap into the groove using the recovery `~
properties of the rubber of the toe in combination with the reinforcement ply 9 . When fully inflated the toe positively ., . ; -:
engages in the groove as shown in Figures 1 and 3 so that the toe end 10 is radially and axially located in the groove base 15 and the toe is under a degree of precompression between the groove and the bead wire 4.
To ensure correct fitting the straightened toe length -~ H measured from the heel point H.P.l to the toe end 10 must `~
.: 1 .
be less than the distance from the heel point H.P.2 of the rim along the bead seat 18-18 and to the nearest point on tha inboard face 19 of the groove 15 i.e. the length of the line H2.
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In the embodiments described to ensure tyre fitting the distance measured in the axial direction from the vertical part of the flange to the centre line of the groove must be at least the same as the axial distance from the end of the toe to the flange contacting vertical part of the bead beore the tyre is fitted. These dimensions are both 20 mm in the examples.
Tyre bead removal is shown in Figure 10. Conventional tyre removal tools comprise a spade ended tool 20 which is engaged between the wheel rim flange 21 and i8 then forced towards the centre of the tyre wheel assembly in the axial ` direction. The force does not produce any substantial bead ; rotation and the tyre bead can be successfully dislodged with the toe flexing sideways and without any damage to the tyre bead or toe.
The tyre wheel assemblies described above in relation to Figures 1 -5 were tested as the outer front wheel in a J
turn test (i.e. straight running followed by a full steering lock application) with the valve core removed. The test was repeated at successively higher speeds on a high grip tarmac~
surface. ~either of the embodiments dislodged at 40 mph which represents an applied side accele~ation of the order of 1 g.
Higher speeds do not apply greater side force to the tyre since under such conditions the vehicle slides. In Slalom testing at speeds in excess of 70 mph when the direction of the side force changed bead dislodgement did not occur. The ; assemblies were similarly proved on all other wheel positions.
Accordingly the assemblies were absolutely safe from . . .
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dislodgement at the maximum sideforce available even under extreme test conditions.
Even after the above tests the tyres were readily removed from the rims using a conventional hand-operated tyre demounting machine.
Filmed evidence of the tyre behaviour on the rim confirmed that the tyre bead moves in the ground contact area to lock the tyre to the wheel rim in the manner described. ~ :
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Different rim widths and tyre sizes have been tested successfully using bead locks to the present invention. In the case of different rim widths different material thicknesses may be required for wheel rim strength and to allow convenient rolling the groove dimensions are changed accordingly. The tyre toe dimensions are also changed in proportion and the invention operates precisely as in the detailed case described above.
The invention operates with different tyre section widths, aspect ratios and bead diameters and applies also to all other known tyre constructions tubed or tubeless including - radial ply tyres, belted bias tyres, cross-ply tyres and run-flat 'Denovo' (Registered Trade Mark) type tyres.
The bead lock is preerably applied to both tyre beads although it may be applied to only the inboard or outboard bead.
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Claims (7)
1. A one-piece wheel rim for a tubeless pneumatic tyre wheren the radially outer profile of the wheel rim considered in a plane containing the axis of the wheel rim comprises, in sequence, from one edge of the wheel rim profile:-a radially extending bead retaining flange having a radially outer edge which is turned axially outwardly;
a curved seating portion for the heel of a tyre bead;
a substantially straight main bead seating portion which tapers radially inwardly towards the axially inner regions of the wheel rim;
an open bead toe locating groove immediately adjacent to said bead seating portion formed by, again in sequence:-a radially inwardly curving axially outer groove edge portion having a radius in the range of 5mm to 8mm;
an outwardly concave groove base portion having a radius in the range of 3mm to 5mm; and a radially inwardly curving axially inner groove edge portion having a radius in the range of 5mm to 8mm;
a substantially straight flat ledge portion;
a central tyre-fitting well portion having a diameter substantially smaller than the main bead seating portion and arranged to allow tyre fitting over the tyre retaining flange:
a second open bead toe locating groove formed by, again in sequence:-a radially inwardly curving axially inner groove edge portion having a radius in the range of 5mm to 8mm;
an outwardly concave groove base portion having a radius in the range of 3mm to 5mm; and a radially inwardly curving axially outer groove edge portion having a radius in the range of 5mm to 8mm;
a substantially straight main bead seating portion which tapers radially inwardly towards the axially inner regions of the wheel rim; and a radially extending bead retaining flange having a radially outer edge which is turned axially outwardly.
a curved seating portion for the heel of a tyre bead;
a substantially straight main bead seating portion which tapers radially inwardly towards the axially inner regions of the wheel rim;
an open bead toe locating groove immediately adjacent to said bead seating portion formed by, again in sequence:-a radially inwardly curving axially outer groove edge portion having a radius in the range of 5mm to 8mm;
an outwardly concave groove base portion having a radius in the range of 3mm to 5mm; and a radially inwardly curving axially inner groove edge portion having a radius in the range of 5mm to 8mm;
a substantially straight flat ledge portion;
a central tyre-fitting well portion having a diameter substantially smaller than the main bead seating portion and arranged to allow tyre fitting over the tyre retaining flange:
a second open bead toe locating groove formed by, again in sequence:-a radially inwardly curving axially inner groove edge portion having a radius in the range of 5mm to 8mm;
an outwardly concave groove base portion having a radius in the range of 3mm to 5mm; and a radially inwardly curving axially outer groove edge portion having a radius in the range of 5mm to 8mm;
a substantially straight main bead seating portion which tapers radially inwardly towards the axially inner regions of the wheel rim; and a radially extending bead retaining flange having a radially outer edge which is turned axially outwardly.
2. A one-piece wheel rim according to claim 1 wherein each open bead toe locating groove considered in cross-section is symmetrically shaped about a centre line extending radially with respect to the wheel rim through the point of minimum radius of the open locating groove.
3. A one-piece wheel rim according to claim 2 wherein said radial centre line is spaced in an-axial direction from the radially extending bead retaining flange by a distance in the range of 18 - 20mm.
4. A one-piece wheel rim according to claim 3 wherein the said bead seating portions have a diameter in the range of 320/342/595mm and the axial distance between the spaced apart bead retaining flanges is in the range of 95/110/170mm.
5. A one-piece wheel rim according to claim 1 wherein the radial height of each bead retaining flange is in the range of 12 - 13.5 mm and the radial depth of the tyre fitting well is in the range of 13 - 14mm.
6. A one-piece wheel rim according to claim 1 wherein the radially outer edge of each bead retaining flange is turned axially outwardly with a radius in the range of 7 - 9mm.
7. A one-piece wheel rim according to claim 1 where the radially outer edge of each bead retaining flange includes a radially and axially outwardly extending portion which is sub-stantially straight and extends at an angle of 45 to the radial direction.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA338,994A CA1081282A (en) | 1976-06-04 | 1979-11-02 | Tyre and wheel rim assemblies |
Applications Claiming Priority (7)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB23099/76A GB1584553A (en) | 1976-06-04 | 1976-06-04 | Tyre and wheel rim assemblies |
| GB3967076 | 1976-09-24 | ||
| GB3967276 | 1976-09-24 | ||
| GB4268976 | 1976-10-14 | ||
| GB850177 | 1977-03-01 | ||
| GB916177 | 1977-03-04 | ||
| CA338,994A CA1081282A (en) | 1976-06-04 | 1979-11-02 | Tyre and wheel rim assemblies |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1081282A true CA1081282A (en) | 1980-07-08 |
Family
ID=27560897
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA338,994A Expired CA1081282A (en) | 1976-06-04 | 1979-11-02 | Tyre and wheel rim assemblies |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1081282A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110614885A (en) * | 2019-09-16 | 2019-12-27 | 寿光福麦斯轮胎有限公司 | Reinforcing tire bead structure for semisteel tire |
-
1979
- 1979-11-02 CA CA338,994A patent/CA1081282A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110614885A (en) * | 2019-09-16 | 2019-12-27 | 寿光福麦斯轮胎有限公司 | Reinforcing tire bead structure for semisteel tire |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |