GB2299554A

GB2299554A - Pneumatic tyres

Info

Publication number: GB2299554A
Application number: GB9507090A
Authority: GB
Inventors: Russell John Searle
Original assignee: Individual
Current assignee: Individual
Priority date: 1995-04-06
Filing date: 1995-04-06
Publication date: 1996-10-09
Also published as: GB9507090D0

Abstract

A tyre is provided with bracing between points on one side of the tyre adjacent to the tread and on the other side of the tyre adjacent to the tyre bead, the bracing comprising either diagonal cords a, b or flexible diaphragms (c, d, e, f, Fig 3). In another embodiment (Fig 4) the tyre wall forms a cruciform section.

Description

The importance of the pneumatic tyre to Road vehicles is fundamental and it has always been accepted that its effectiveness as a means of isolating a vehicle from road undulations is of necessity reduced by its function in providing a stable support for the vehicle. In this respect it must fall short of the ideal of an inertia-less and friction-less air cushion because in addition to the need for an envelope to contain the air, it must have sufficient lateral stiffness to resist centrifugal forces on the vehicle when cornering. Thus the structure of the tyre will also have a degree of vertical rigidity which will transmit the effects of Road undulations to the carcass of the vehicle in the form of noise and vibration, and will also result in high rolling resistance due to the continuous flexing of an envelope having high hysteresis losses.

The present invention proposes a form of tyre construction which gives the tyre lateral stability largely independent of the rigidity of the envelope and its inflation pressure, thereby allowing a vertically compliant envelope which has low road noise transmission and low rolling resistance.

In the invention transverse rigidity of the tyre is obtained by cross-bracing the tyre between points within the envelope adjacent to the tread and points adjacent to the wheel rim, such that bellying of the tyre adjacent to the tread due to change in load compensates for the changing horizontal distance between the points of attachment of the bracing, as shown in Fig.I.

In a practical system the tyre is "laced", as shown in Fig. 2, by two series of flexible but nonextensible cords a & b passing between points in the tyre envelope adjacent to the tread and points adjacent to the wheel rim, such that one series of cords are under tension when a transverse shearing moment exists between the tread of the tyre and the wheel rim. Alternatively, the bracing members may consist of a continuous flexible web of cruciform section as shown in Fig. 3., so that transverse shearing moments tension either members c, d, or members e, f.

In a further arrangement the tyre envelope itself is of a form, such as illustrated in Fig. 4 in which parts of the envelope are under tension when a transverse shearing moment exists, in this case the envelope forms two separate co-planar chambers g & h, which may be at different pressures or may be interconnected to equalise their internal pressure.

At the point ofjunction of the chambers, there may be incorporated a relatively rigid annular band j., which when the chamber h is compressed in response to road undulations the band is displaced radially relative to the rim of the wheel and is distorted into an elliptical shape thus giving the tyre a non-linear load I deflection characteristic.

Claims

1) A pneumatic tyre for wheeled vehicles wherein the tyre has a structural element which is under tension in a direction transverse to the tyre when the tyre is subjected to a shearing force acting between the tread of the tyre and the wheel.

2) A pneumatic tyre for wheeled vehicles according to the first claim wherein the tyre is braced internally between one side of the tyre adjacent to the rim and the opposite side of the tyre adjacent to the tread.

3) A pneumatic tyre according to the first claim wherein each side of the tyre adjacent to the tread is cross-braced to the opposite side of the tyre adjacent to the wheel rim.

4) A pneumatic tyre according to the first or second claim wherein a series of flexible but substantially non-extensible members form the bracing previously described.

5) A pneumatic tyre according to the first, second or third claim wherein the bracing consists of a flexible non-extensible membrane.

6) A pneumatic tyre according to the fourth claim wherein the bracing consists of membranes joining the tyre internally between points adjacent to each side of the tread and points adjacent to each side of the wheel rim the membranes forming a cruciform across the section of the tyre.

7) A pneumatic tyre according to the first claim wherein the tyre is formed from two concentric co-planar toroidal chambers the adjacent walls of which form in section a cruciform which braces each side of the tyre adjacent to the tread to the opposite sides of the tyre, adjacent to the wheel rim.

8) A pneumatic tyre according to the seventh claim wherein a relatively rigid annular band is incorporated in the tyre at the point of junction of the concentric toroidal chambers.