Resilient tires and wheels – Tires – resilient – Anti-skid devices
Patent
1988-10-25
1990-05-01
Dawson, Robert A.
Resilient tires and wheels
Tires, resilient
Anti-skid devices
152208, B60C 1114
Patent
active
049210300
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention concerns a sleeve-mounted spike fitted on a vehicle tyre, comprising a rivet, a head, a tip and a sleeve.
The road attrition effect of spiked tyres has been found to be mainly due to the impact action of the spike in the road contact situation and to the scratching effect from the spike when the spike is pressed against the road surface in conditions of load-bearing tyre, and particularly due to the scratching effect at the very moment when the spike is losing road contact.
The impact produced in the road contact situation of the spike results from the kinetic energy of the spike, from the resisting visco-elastic nature of the rubber and from the friction counter-acting the movement of the spike. The impact at first contact and the road attrition effect can therefore be substantially reduced by removing the causative factors of these phenomena. The expedient of reducing the kinetic energy of the spike by reducing its weight is already known in the art. The object of the present invention is to reduce the other harmful effects.
The scratching effect of the spike, as the tyre rolls, is due to the difference between the radius of the wearing surface and the true radius of rotation, this differential giving rise to a slipping tendency of the tyre surface and thereby producing the scratching effect of the spike. The stress from said slipping tendency is discharged just at the moment when the spike contact ends, and at this time the scratching effect is also at its maximum.
SUMMARY OF THE INVENTION
The object of the invention is to achieve an improvement of sleeve-mounted spikes known in the art. The more detailed object of the invention is to provide a sleeve-mounted spike which reduces the visco-elastic impact from the rubber and the friction of the rivet at the moment when road contact begins, and in which during the road contact situation the scratching phenomenon is avoided, which occurs particularly in its late part.
The objects of the invention are achieved with a sleeve-mounted spike which is maintaly characterized in that the clearance between the sleeve and the rivet increases in the direction towards the tip.
In an advantageous embodiment of the invention, the sleeve has been shaped so that the hole for the rivet in the sleeve has been disposed to increase in diameter towards the tip.
In another advantageous embodiment of the invention, the rivet is shaped so that the diameter of the rivet has been disposed to decrease towards the tip.
The clearance according to the invention may be either symmetrical or asymmetrical.
Significant advantages are gained with the sleeve-mounted spike of the invention. Since in the sleeve-mounted spike either the mouth portion of the sleeve has been made wider or the rivet has been tapered in the direction towards the tip, whereby the tip is enabled to move and the first contact of the tip of the sleeve-mounted spike, which produces road attrition, becomes softer, because the head of the rivet transfers the impact resulting from first contact to the tyre rubber mainly by one of its margins. Similarly, the slipping tendency of the rubber of the vehicle tyre during road contact causes no scratching effect of the tip on the road surface because the construction of the sleeve-mounted spike of the invention permits such movement of the tyre surface due to slipping tendency, independent of the movement of the spike tip. Similar movements of the rivet within the sleeve, due to the slipping tendencies of the rubber, also occur in the direction transverse to the direction of travel, although they are smaller. As a result of soft first contact, and of the fact that the rubber material of the tyre can move freely during road contact while the tip is substantially stationary relative to the road, the rod attrition effect of the sleeve-mounted spike of the invention is considerably less than that encountered with sleeve-mounted spikes of prior art.
BRIEF DESCRIPTION OF THE DRAWING
The invention is described in detail, referring
REFERENCES:
patent: 3786849 (1974-01-01), Loqvist
patent: 4875515 (1989-10-01), Suvanto
Dawson Robert A.
Neste Oy
Wilber Gregory J.
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