Run flat banded pneumatic tire
AssigneeBridgestone/Firestone, Inc.
InventorsCharles D. Spragg, Edward G. Markow, Thomas W. Bell
Life of this patent
Estimating the term…
Abstract
A run flat pneumatic tire is reinforced by a thin annular composite band imbedded in the crown portion of the tire in combination with a plurality of radial cords or plies in its sidewalls which have freedom in shear with respect to one another. The band is formed by a plurality of layers of material strips wherein each strip is wound in a helical pattern, with adjacent strips being wound at reverse angles to each other. Each layer is formed under sufficient pressure and at an elevated temperature whereby the band is prestressed in tension which decreases the maximum stress at the footprint area of the tire. The invention furthermore incorporates the method of imparting the prestress on the annular band during its manufacture.
Claims25
In a run flat pneumatic tire including an elastomeric casing with a tread formed in a crown portion thereof and sidewalls extending from the crown portion to generally circular beads adapted to normally seat themselves in airtight secured relationship with a wheel, a combined structure for resisting compressive forces on the tire when deflated, the structure comprising:
- a continuous thin annular composite band fixed in said tire radially inwardly of said tread, said band having a width substantially spanning the width of the crown portion and including a plurality of helically wound adjacently positioned flat strips of material forming a plurality of wound layers of material strips with at least a portion of said strips located in outermost layers of said composite band being prestressed in tension to decrease the maximum stress at a footprint area of the tire;
- and
- means to radially stabilize said annular band comprising a multiplicity of closely spaced substantially radial reinforcing elements having freedom in shear with respect to one another in said sidewalls operatively connected to said beads and extending therefrom to at least the crown portion of the tire and being operatively connected to said annular band.
In a method for building a run flat pneumatic tire, the tire including:
- an elastomeric casing with a tread formed in a crown portion thereof and sidewalls extending from the crown portion to generally circular beads adapted to normally seat themselves in airtight secured relationship with a wheel, a combined structure for resisting compressive forces on the tire when deflated, the structure comprising:
- a continuous thin annular composite band fixed in said tire radially inwardly of said tread, said band having a width substantially spanning the width of the crown portion and including a plurality of helically wound adjacently positioned flat strips of material forming a plurality of wound layers of material strips with at least a portion of said strips located in outermost layers of said composite band being prestressed in tension to decrease the maximum stress at a footprint area of the tire;
- and
- means to radially stabilize said annular band comprising a multiplicity of closely spaced substantially radial reinforcing elements having freedom in shear with respect to one another in said sidewalls operatively connected to said beads and extending therefrom to at least the crown portion of the tire and being operatively connected to said annular band;
- the method including the steps of:
- forming a thin annular composite band having a width substantially spanning the width of the crown portion by wrapping a plurality of strips of material in overlapping alternating helical configurations around a mandrel to form the band with a plurality of strip layers;
- maintaining the strips at an elevated temperature sufficient to provide a tacky consistency to said strips as said strips are being wrapped around the mandrel;
- applying sufficient tension to the strips as they are being wrapped around the mandrel to substantially eliminate voids between the overlapping strip layers;
- cooling the strip layers after being applied under pressure around the mandrel whereby thermal shrinkage of said strips prestresses the formed band in tension;
- embedding the prestressed band inside the crown portion of the tire;
- and
- curing the resulting tire wherein the prestressed band in cooperation with the radial stabilizing elements in the sidewalls resist compressive forces encountered upon deflation of the tire.
Dependencies are inferred from the claim text.