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US 4,051,884 AGranted
Pneumatic tire containing gel lubricant
AssigneeDunlop Limited
InventorsAlan John Bourne, Trevor John Walton
Life of this patent
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AssigneeDunlop Limited
InventorsAlan John Bourne, Trevor John Walton
Estimating the term…
A lubricant gel is made from a poly(alkylene oxide) lubricant, a finely divided silica and a gel-strengthening amount of an ionic salt having a pH of 5.5-8.5 when in 0.1 M aqueous solution. The gel is useful in the inflation chamber of a pnemuatic tire to enable it to run safely in a deflated condition for which purpose the gel should have the required viscosity and mechanical stability.
A pneumatic tire having on its internal surface a coating of a lubricant gel having a viscosity and mechanical stability such that it remains on the tire surface and does not flow when the tire is in normal use in an inflated tire and wheel assembly, said gel comprising a poly(alkylene oxide) lubricant gelled with a finely divided silica having a surface area above 150 square meters/gram and a gel-strengthening amount of an ionic salt having a pH in the range 5.5 to 8.5 when in a 0.1 molar aqueous solution, said salt being capable of producing a gel viscosity (measured at 20.degree. C at a shear rate of 0.31 reciprocal seconds) in the range 3000 to 7000 Newton.seconds per square meter by mixing 2 milliliters of a suitably concentrated aqueous solution of the salt with 100 grams of the poly(alkylene oxide) lubricant and the silica in a lubricant:silica weight ratio of not greater than 92.5:7.5.
Dependencies are inferred from the claim text.
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No related US applications are recorded in the indexed filing history.
Parts of pneumatic tyres; accessories, auxiliary operations: incorporating auto-repairing or self-sealing arrangements or agents on or into tyres
Component parts, details, accessories or auxiliary operations, not covered by group B29C33/00 or B29C35/00: using separating agents during or…
Tyres characterised by means enabling restricted operation in damaged or deflated condition; Accessories therefor: internal lubrication
Silicon-containing compounds: silica
Term ended 4 Oct 1994 (estimated)
USPTO file history isn’t available for this patent, so only indexed dates are shown.
This invention relates to gel systems, particularly to gelled lubricants suitable for lubricating the interior of a pneumatic tire and wheel assembly when run in a deflated or under-inflated condition.
There are now pneumatic tire and wheel assemblies which are designed such that they may be run in a completely deflated or under-inflated condition much more safely than can conventional assemblies. Examples of such assemblies are described in U.K. patent specifications Nos. 1,359,467, 1,359,468 and 1,359,461, and a well-known example of such an assembly is that available under the U.K. registered Trade Mark DENOVO.
In order to reduce the friction between the tire and wheel surfaces which contact each other inside the inflation chamber when an assembly is run in a deflated or under-inflated condition, it has been proposed to lubricate these surfaces by means of a liquid lubricant. A preferred means by which the lubricant is stored inside the inflation chamber is in the form of a grease or gel which is capable of breaking down to release the lubricant when it is required for use. Various lubricants and gels have been proposed, for example those referred to in U.S. patent application Ser. No. 657,057 which is a continuation-in-part of U.S. patent application Ser. No. 392,552, U.S. Pat. No. 3,931,843 and U.S. Pat. No. 3,946,783.
A tire in accordance with the invention is shown in the accompanying drawings in which:
FIG. 1 is a schematic cross-sectional view of the tire having a coating of gelled composition on the interior of the tire tread the tire being in the inflated condition, and
FIG. 2 is a similar view through the tire/ground contact area of the tire with the tire in a deflated condition, under vertical load but not subject to a lateral (e.g. cornering) force.
As shown in FIG. 1 the tire is a radial tire having a tread 1 braced by a breaker assembly 2 comprising two folded breaker plies, sidewalls 3 and beads 4. A carcass reinforcement 5 consisting of a pair of rayon cord plies having equal and opposite bias angles of 88.degree. relative to the mid-circumferential plane extends from bead to bead.
The tire is shown on a rim 6 narrower than the tread of the tire, and having a notch 7 positioned adjacent its outboard bead seat. Such a rim may be a split rim as described in our U.K. Patent specification Ser. No. 1,432,545, or an axially compressed rim in which a well has been closed up by axial compression as described in our U.K. patent specification Ser. No. 1,348,891.
Each bead 4 of the tire is provided with an extended toe portion 8, that on the outboard bead, 8a, resting in the notch 7 in the rim and that on the inboard bead, 8b, being stretched over the rim.