Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
1998-10-01
2001-03-13
Maki, Steven D. (Department: 1733)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C152S209110, C152S209170, C152S209280, C152S903000, C152S904000, C703S001000, C703S008000
Reexamination Certificate
active
06200401
ABSTRACT:
The invention relates to a tire for a two-wheeled vehicle such as a motorcycle or motorscooter.
Such tires utilize treads which in transverse cross-section are sharply curved to provide good contact with the road surface when the motorcycle is steeply banked during cornering.
In common with most other types of tires, in order for these tires to perform well under all conditions it is usual for the ground contacting tread region of the tire to be provided with relatively deep grooves in the surface. In wet conditions such grooves assist in clearing water from the contact area between the tire tread and the road surface and thus help to retain steering control of the vehicle by preventing aquaplaning.
However the provision of such grooves effectively weakens the tire tread and renders it more prone to wear. This occurs because such grooves divide the tread into discrete elements such as ribs and blocks which individually are more susceptible to deformation in the tire/ground contact region due to the tractive and cornering forces transmitted therein and therefore wear by abrasion against the road surface.
In making the present invention, the inventors studied the alignment of the grooves of the tire tread and determined that it was possible to arrange these so as to minimize wear of the tread rubber and thus extend the useful life of the tire.
Accordingly it is an object of the present invention to provide a tire for a two-wheeled vehicle and a method of designing said tire which is improved in tread wear.
According to the present invention a tire for a two-wheeled vehicle comprises a ground contacting tread having tread grooves formed therein, characterized in that in a first region of the tire tread, which is the central tread region and is the region of contact between the tire and the ground when the motorcycle is in the condition of moving in a straight line, the alignment of the tread grooves is substantially circumferential, and in a second region of the tire tread, which is at the axial edge of the tread and is the region of contact when the motorcycle is in the condition of turning under maximum cornering, the alignment of the tread grooves is substantially transverse, and in a third region, which is the tread region between the first central region and the second axial region and which provide the ground contacting regions when the motorcycle is turning at less than the maximum cornering condition, the groove alignment changes progressively axially outwardly from substantially circumferential to substantially transverse so that in the ground contacting region when it is in the first, second or third region the tread grooves are substantially aligned with the resultant forces acting on the tire tread surface.
Preferably in the third region of the tread the alignment of the groove at any axial point is the same as the direction of the force resultant from the addition of the longitudinal and lateral forces acting on the tread at that point when the motorcycle on which the tire is mounted is cornered at constant longitudinal acceleration such that said axial point is at the center of the contact region. The tread grooves are preferably continuous from the tread center to the tread edge.
According to another aspect the invention provides a method of determining the required tread groove angle to form the tread pattern of a tire for a two-wheeled vehicle to give optimum tread wear comprising at successive axial points across the tread from the center to the tread edge aligning the tread groove in the direction of the typical slippage of the tread at that axial point when the point is in the tire/road contact region.
A preferred method of the invention provides a method of determining the required tread groove angle to form the tread pattern of a tire for a two-wheeled motorcycle to give optimized tread wear in use on a motorcycle comprising deciding on the typical longitudinal acceleration of the motorcycle during cornering in the particular manner of riding and determining the corresponding longitudinal force on the tire, and subsequently for successive axial points across the tread surface from the tread center to the tread edge corresponding to successive values of camber of the tire determining the lateral acceleration of the tire and the corresponding lateral force on the tire, determining the direction of the force resultant from the addition of the longitudinal and lateral forces and aligning the tread groove portion at that particular axial point with the direction of the determined resultant force.
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Jackson Michael
Watkins David Robert
Birch & Stewart Kolasch & Birch, LLP
Maki Steven D.
Sumitomo Rubber Industries Limited
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