Resilient tires and wheels – Tires – resilient – Patches
Patent
1981-06-08
1983-07-19
Kimlin, Edward C.
Resilient tires and wheels
Tires, resilient
Patches
152361R, 152366, 1523793, 152386, 152395, 152396, 152DIG17, 301 95, B60C 900, B60C 500, B60B 2100, B60B 2500
Patent
active
043939139
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
This invention relates generally to tire construction and more particularly to means for the reduction of rolling resistance by establishing a tire-rim interface for decreasing movement of the tire bead seat portion with respect to the rim.
2. Background Art
It is well known that the rolling resistance of the tires of a moving vehicle constitutes a significant portion of the resistive force that must be overcome by the vehicle. This is especially true for those vehicles having pneumatic tires. The losses owing to rolling resistance in tires often amount to as much as 15% of the power produced by the vehicle's engine.
There are three prime sources occasioning these rolling resistance losses. A reduction in these losses would be desirable. The first of the three sources of rolling resistance, aerodynamic drag, generally amounts to less than 5% of the total rolling resistance of the tire and hence is relatively insignificant. The second, tire-to-ground frictional losses typically contributes between 10 to 20 percent of the total rolling resistance of the tires. However, it is generally disadvantageous to decrease the tire-to-ground losses. This is due to the fact that traction is a concomitant of these tire-road frictional losses, consequently these losses yield necessary safety and motive advantages.
The third, and by far the greatest, cause of rolling resistance in pneumatic tires results from losses internal to the tire itself. In an operational mode the tire rolls, thus there is a loading of each differential unit of the elastomeric material comprising the tire. The loading is cyclical. Consequently, adjacent portions of the tire periodically move relative to each other, expending energy in the process. Such losses are termed "hysteresis losses".
This cyclically loading, causing tire deformation, also tends to cause movement of the tire relative to the rim supporting it. Standard elastomeric tires are generally structured so that beads of the tire are retained on the rim by an axially directed interference fit. For closed torus tires, the roll-restraining hoops (RRH), which are retained by a radially directed interference fit, achieve this function. In many tires this interference fit permits relative circumferential and/or axial motion between the bead or RRH and the rim as the tire rotates. This relative motion results in frictional losses additional to the hysteresis losses. It is believed that at any given time only the most greatly loaded portion of the rim contacting portion of the tire moves significantly relative to the rim. Such localized relative motion is termed "scrubbing".
"Scrubbing" serves not only to waste energy, but is especially detrimental in that most of this wasted energy is degraded to heat. Heat build up can actually impose an operating limitation on the vehicle in that the loading and duration of operation of the tires should not be above a recommended operational temperature.
These losses internal to the tire and wheel assembly are especially troublesome in the aircraft and heavy equipment industries. The rate at which energy is expended by the relative motion discussed above is directly related in magnitude to both the loading induced deflection of the tire and the rate of rotation of the wheel. The heat buildup in tires under great deflection, as in heavy earthmoving vehicles, is, then, very pronounced. Even with established speed and load limitations, such tires are often destroyed or damaged due to overheating.
Similarly, with aircraft becoming increasing greater in weight and landing speed, aircraft tire manufacturers are facing ever-greater heat buildup problems. The operating pressure of many aircraft tires has been increased in efforts to stiffen the tire and hence decrease rolling resistance. This has served to decrease heat build-up. However, the use of elevated pressure has had the detrimental concomitant of increasing the loading imposed by the aircraft on runways resulting, in some instances, in accelerated runway deterioration. Some a
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Grawey Charles E.
Groezinger John J.
Bokan Thomas
Caterpillar Tractor Co.
Grant John W.
Kimlin Edward C.
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