GB1600989A - Reflation pumps for pneumatic tyre and wheel rim assemblies - Google Patents

Description

(54) IMPROVEMENTS IN OR RELATING TO REFLATION PUMPS FOR PNEUMATIC TYRE AND WHEEL RIM ASSEMBLIES (71) We, DUNLOP LIMITED, a British Company of Dunlop House, Ryder Street, St James's, London, SW1, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to reflation pumps for pneumatic tyre and wheel rim assemblies and in particular to an improvement in or modification of the assembly claimed in our United Kingdom Patent No 1457404.

United Kingdom Patent No 1457404 claims a pneumatic tyre and wheel rim assembly comprising a tyre and a wheel rim defining an inflation chamber, means for preventing the tyre from being demounted rom the wheel rim when the assembly is running deflated, a pump capable of supplying air to the inflation chamber and operable by the cyclic deflection of the tyre arising when the assembly is running deflated, and a lubricating material for facilitating relative movement between contacting regions of the interior surface of the tyre when the assembly is running deflated.

When a tubeless tyre of a road vehicle suffers a puncture resulting in substantial deflation the usual result is that the vehicle becomes immobilised till a replacement tyre, or wheel and tyre assembly, can be fitted. However, if only a relatively small air pressure, for example, 5 p.s.i. can be retained in the tyre it is generally possible for the vehicle to be driven, at least as far as a repair station.

The present invention provides a reflation pump for location inside a road vehicle tyre which is mounted on a wheel rim, which can automatically come into effect to pump air into a deflated tyre while the vehicle is in motion.

Accordingly, the invention provides a pneumatic tyre and wheel rim assembly comprising a tyre and wheel rim defining an inflation chamber, means for preventing the tyre from being demounted from the wheel rim when the assembly is running deflated, a lubricating material for facilitating relative movement between contacting regions of the interior surface of the tyre when the assembly is running deflated, and a reflation pump for the tyre, the pump comprising: a bellows formed from a resilient material and having an inlet for air drawn by the bellows from the exterior of the tyre, an outlet for air forced by the bellows into the tyre; an inlet valve to prevent air from escaping from the bellows through the inlet port; an outlet valve to prevent air from escaping from the tyre through the outlet port into the bellows; means responsive to deformation of the tyre on substantial deflation thereof in use, said means being arranged to actuate the bellows upon said substantial deflation occurring; and means to secure the reflation pump to the wheel rim.

The bellows conveniently is of elastomeric material having two opposed conical portions each having an aperture located therein, said conical portions defining therebetween a bellows chamber when the material is in its undeformed state, and said bellows in such as to be resiliently deformable by pressure exerted in a direction to deflate the bellows to expel air from the bellows chamber, and to resile to suck air into the bellows chamber.

Said apertures can constitute respectively an inlet and outlet for air drawn into and expelled from the bellows chamber.

The pump may be formed as a single or plural convolution bellows.

The means responsive to deformation of the tyre on substantial deflation thereof in use is conveniently a striking cap which, when the tyre is substantially deflated, is struck repeatedly as the tyre revolves in contact with the road, and it is with respect to the use of striking caps or other strikers that the following description relates. The striking cap or other striker is convenienty mounted on the bellows and, for example, it can be a portion of the bellows itself. In a preferred form the striking cap is provided by a boss moulded integrally as part of a rubber bellows.

The reflation pump is mounted within the tyre in such a way that, when the tyre becomes substantially deflated, the striking cap is struck as the wheel rotates with its tyre in contact with the ground thereby actuating the bellows, as is described in greater detail below. The striking cap is struck by the coincident area of the inner surface of the tread, and as the wheel and tyre rotates, striking takes place automatically in the tyre/road contact area when substantial deflation of the tyre occurs. The pump should preferably be dimensionally designed so that the distance between the striker cap and the inside tread diameter of the tyre is sufficiently great to preclude unwanted striking, i.e. when the tyre is fully or substantially fully inflated.

The pump is normally attached to the rim of the wheel carrying the tyre.

A tyre reflation pump which is part of an embodiment of the invention will now be described by way of example with reference to the drawing accompanying the provisional specification, the sole figure of which is an elevation in section of the pump mounted on a wheel rim, and the tyre is not shown.

In the drawing a moulding 10 comprises a deformable rubber bellows 11 (shown in its undeformed condition) defining a bellows chamber gila. The bellows 11 has opposed conical portions lib, lic, together defining a single-convolution bellows. (It is within the scope of the invention to employ, instead, a plural convolution bellows). At one end the bellows merges into a hollow cyclindrical base portion 12, said portion having a circumferential groove 13 of rectangular cross-section. The other end of the chamber 11a has a cylindrical rubber boss 14 which is substantially solid but has a central conduit 15 communicating between the interior of the bellows 10 and a transverse conduit 16 arranged diametrically inside said boss 14 and leading to two diametrically opposed outlet ports 17 in a circular rebate 18 in the outer surface of the boss 14. The head of the boss 14 is formed as a striking cap 19 integral with the boss 14.

The hollow cylindrical base portion of the bellows 10 accommodates a metal sleeve 20 which has a flange 21 in engagement with the groove 13. The sleeve 20 is open at the end thereof distant from the bellows chamber lla, and in said open end there is located a tubular stem 22 fixed to the metal sleeve 20. The other end of the metal sleeve 20 has a ring of apertures 23 therein which constitute the inlet port of the bellows 10, and an umbrella valve 24 arranged over said apertures 23 is a one-way valve which permits air to be sucked into the bellows chamber lia but prevents air from passing in the opposite direction and so escaping back out of the bellows chamber lla. In the circular rebate 18 there is located a sleeve of elastomeric material 25, which conveniently is a rubber band, of dimensions such that it is a snug fit in the rebate 18. This band 25 acts as a one-way valve which permits air to be expelled by the bellows 10 through the outlet ports 17 into the tyre (not shown), but prevents air from passing from the tyre back into the bellows chamber 11a.

In the drawing the relation pump is shown engaging a wheel rim 26, the hollow stem 22 being a snug fit in an aperture in the rim 26 and protruding beyond it. A washer and nut (not shown) are carried by the stem 22 to hold the stem 22, and consequently the pump as a whole, in position against the rim 26. The washer/nut assembly may include a suitable sealing ring (not shown) additional to the seal provided by the base of the bellows, as hereinafter described.

A metal clamping ring 27 embraces the exterior of the hollow cylindrical base portion 12, and has an outwardly directed conical flange 28 which contacts the radially inner portion 11c of the exterior of the bellows chamber lla. At least the lower part of the clamping ring 27 is fixed by the exterior of the bellows chamber lla.

It will be appreciated that tightening of the nut (not shown) carried by the stem 22 has the effect of urging the end of the bellows base 12 against the rim 26. Preferably one or both of the clamping ring 27 and the sleeve 20 is located so as to be spaced apart a small distance 30 from the rim 26, and pressure of the end of the bellows base 12 against the rim 26 results in the end of it extending into the gap 30 between the end of the ring 27 and/or the end of the sleeve 20 and the rim 26, thereby effecting a seal between the wheel rim 26 and the air chamber of the tyre.

The reflation pump works as follows.

When the tyre loses some or all of its air as the result of a puncture or a leaking valve, for example, the height of the rim 26 above the interior surface of the tyre tread (not shown) at the area of contact with the road (not shown) is decreased until the striking cap 19 (which is always clear of the tyre when the tyre is inflated to its recommended pressure) begins to strike the inner surface of the tyre each time the wheel rotates to bring the deflation pump adjacent the area of contact between road and tyre. When struck in this way the cap 19 is displaced towards the rim 26 thereby causing the bellows 11 to be compressively deformed, thus lifting the outlet valve 25 from its seating and expelling air from the bellows chamber 11a through the outlet ports 17 into the tyre. Air is prevented from leaving the other end of the chamber 11a, during compression of the bellows 11, by the umbrella valve 24 which is pushed down on its seat. Once this flow of air ceases the outlet valve 25 resiles back onto its seating thereby preventing air from escaping from the tyre into the bellows 10. Further rotation of the wheel results in the cap 19 moving out of contact with the inside of the tread and the bellows resuming its original shape and in so doing to suck air through the stem 22 causing the umbrella valve 24 to rise, and the air to pass into the bellows chamber 11a. Once the chamber 11a has assumed its undeformed shape, air ceases to be sucked in, and the umbrella valve 24 resumes its closed position in which the apertures 23 are closed off. The above cycle of events is repeated on subsequent revolutions of the wheel.

Where the leak rate is not excessive, the pump feeds air into the tyre at a rate which compensates for loss of air through, for example, a puncture, and a sufficient air pressure is maintained in the tyre which allows the vehicle to be driven to a place of repair. The effect of this air pressure is to reduce the deflection of that part of the tyre sidewall which is coming into contact with the road; consequently the pump amplitude will become less, and less air will be pumped into the tyre per revolution. An equilibrium will be established when the rate at which air is pumped into the tyre equals the rate of loss of air from the tyre through the puncture and/or other leak.

For reasons of manufacturing economy it is preferred to make the bellows 11 of a one-piece moulding 10 as shown on the drawing, but it is within the scope of the invention that the bellows 11 could be fabricated from a plurality of components (not shown) mutually secured by any suitable means.

Means (not shown) for preventing the tyre from being demounted from the wheel rim when the assembly is running deflated can take any suitable form, for example as described in our U.K. Patent Specifications 1457404 and 1395714.

Suitable lubricating materials are described, for example, in our U.K. Patent Specification No. 1359467.

WHAT WE CLAIM IS: 1. A pneumatic tyre and wheel rim assembly comprising a tyre and wheel rim defining an inflation chamber, means for preventing the tyre from being demounted from the wheel rim when the assembly is running deflated, a lubricating material for facilitating relative movement between contacting regions of the interior surface of the tyre when the assembly is running deflated, and a reflation pump for the tyre, the pump comprising a bellows formed from a resilient material and having an inlet for air drawn by the bellows from the exterior of the tyre, an outlet for air forced by the bellows into the tyre; an inlet valve to prevent air from escaping from the bellows through the inlet port; an outlet valve to prevent air from escaping from the tyre through the outlet port into the bellows; means responsive to deformation of the tyre on substantial deflation thereqf in use, said means being arranged to actuate the bellows upon said substantial deflation occurring; and means to secure the reflation pump to the wheel rim.

2. An assembly according to claim 1 wherein the bellows is of elastomeric material and has two opposed conical portions each having an aperture located therein, said concial portions defining therebetween a bellows chamber when the material is in its undeformed state, and said bellows is such as to be resiliently deformable by pressure exerted in a direction to deflate the bellows to expel air from the bellows chamber, and to resile to suck air into the bellows chamber.

3. An assembly according to claim 2 wherein said apertures constitute respectively an inlet and an outlet for air drawn into and expelled from the bellows chamber.

4. An assembly according to claim 3 wherein said outlet valve is a taut layer of elastomeric material resting, except when open to pass air, against the bounds of the aperture defining said outlet port.

5. An assembly according to claim 4 wherein said layer of elastomeric material is a rubber band stretched around the bellows wall which is further from the rim upon which the pump is mounted.

6. An assembly according to any preceding claim wherein said bellows is formed as a one-piece moulding.

7. An assembly according to any preceding claim wherein said bellows is a single-convolution bellows.

8. An assembly according to any claims 1 - 6 wherein said bellows is a pluralconvolution bellows.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (9)

**WARNING** start of CLMS field may overlap end of DESC **. of contact between road and tyre. When struck in this way the cap 19 is displaced towards the rim 26 thereby causing the bellows 11 to be compressively deformed, thus lifting the outlet valve 25 from its seating and expelling air from the bellows chamber 11a through the outlet ports 17 into the tyre. Air is prevented from leaving the other end of the chamber 11a, during compression of the bellows 11, by the umbrella valve 24 which is pushed down on its seat. Once this flow of air ceases the outlet valve 25 resiles back onto its seating thereby preventing air from escaping from the tyre into the bellows 10. Further rotation of the wheel results in the cap 19 moving out of contact with the inside of the tread and the bellows resuming its original shape and in so doing to suck air through the stem 22 causing the umbrella valve 24 to rise, and the air to pass into the bellows chamber 11a. Once the chamber 11a has assumed its undeformed shape, air ceases to be sucked in, and the umbrella valve 24 resumes its closed position in which the apertures 23 are closed off. The above cycle of events is repeated on subsequent revolutions of the wheel. Where the leak rate is not excessive, the pump feeds air into the tyre at a rate which compensates for loss of air through, for example, a puncture, and a sufficient air pressure is maintained in the tyre which allows the vehicle to be driven to a place of repair. The effect of this air pressure is to reduce the deflection of that part of the tyre sidewall which is coming into contact with the road; consequently the pump amplitude will become less, and less air will be pumped into the tyre per revolution. An equilibrium will be established when the rate at which air is pumped into the tyre equals the rate of loss of air from the tyre through the puncture and/or other leak. For reasons of manufacturing economy it is preferred to make the bellows 11 of a one-piece moulding 10 as shown on the drawing, but it is within the scope of the invention that the bellows 11 could be fabricated from a plurality of components (not shown) mutually secured by any suitable means. Means (not shown) for preventing the tyre from being demounted from the wheel rim when the assembly is running deflated can take any suitable form, for example as described in our U.K. Patent Specifications 1457404 and 1395714. Suitable lubricating materials are described, for example, in our U.K. Patent Specification No. 1359467. WHAT WE CLAIM IS:

1. A pneumatic tyre and wheel rim assembly comprising a tyre and wheel rim defining an inflation chamber, means for preventing the tyre from being demounted from the wheel rim when the assembly is running deflated, a lubricating material for facilitating relative movement between contacting regions of the interior surface of the tyre when the assembly is running deflated, and a reflation pump for the tyre, the pump comprising a bellows formed from a resilient material and having an inlet for air drawn by the bellows from the exterior of the tyre, an outlet for air forced by the bellows into the tyre; an inlet valve to prevent air from escaping from the bellows through the inlet port; an outlet valve to prevent air from escaping from the tyre through the outlet port into the bellows; means responsive to deformation of the tyre on substantial deflation thereqf in use, said means being arranged to actuate the bellows upon said substantial deflation occurring; and means to secure the reflation pump to the wheel rim.

2. An assembly according to claim 1 wherein the bellows is of elastomeric material and has two opposed conical portions each having an aperture located therein, said concial portions defining therebetween a bellows chamber when the material is in its undeformed state, and said bellows is such as to be resiliently deformable by pressure exerted in a direction to deflate the bellows to expel air from the bellows chamber, and to resile to suck air into the bellows chamber.

3. An assembly according to claim 2 wherein said apertures constitute respectively an inlet and an outlet for air drawn into and expelled from the bellows chamber.

4. An assembly according to claim 3 wherein said outlet valve is a taut layer of elastomeric material resting, except when open to pass air, against the bounds of the aperture defining said outlet port.

5. An assembly according to claim 4 wherein said layer of elastomeric material is a rubber band stretched around the bellows wall which is further from the rim upon which the pump is mounted.

6. An assembly according to any preceding claim wherein said bellows is formed as a one-piece moulding.

7. An assembly according to any preceding claim wherein said bellows is a single-convolution bellows.

8. An assembly according to any claims 1 - 6 wherein said bellows is a pluralconvolution bellows.

9. A pneumatic tyre and wheel rim

assembly, substantially as hereinbefore described with reference to the drawing accompanying the provisional specification.