GB2280245A

GB2280245A - Tyre valves

Info

Publication number: GB2280245A
Application number: GB9315304A
Authority: GB
Inventors: Edward Thomas Murfitt
Original assignee: Individual
Current assignee: Individual
Priority date: 1993-07-23
Filing date: 1993-07-23
Publication date: 1995-01-25
Also published as: GB9315304D0

Abstract

A tyre pressure adjusting valve comprises body 16 having a bore 18 in communication with an air outlet 19, a ball valve 21 for closing the outlet and a helical spring 22 located coaxially in the bore. The spring yields when tyre pressure exceeds a predetermined pressure, the ball valve lifting off its seat 20 so that air passes out of the tyre until the pressure is reduced to the predetermined pressure. A tyre might also have a pressure entry valve (Fig. 4, not shown), where a spring only allows a ball to lift from a seat when inflation pressure exceeds a given value. Both valve types may be incorporated in one body (Fig. 5, not shown). <IMAGE>

Description

A Valve for a Pneumatic Tyre This invention relates to a valve for a pneumatic tyre.

A pneumatic tyre is provided with a valve holder in which is located a valve for permitting inflow of air under pressure to inflate the tyre but which restrains passage of air in a reverse direction through the valve from the tyre.

In order to ensure that a tyre is inflated at a predetermined pressure, it is generally necessary to inspect an air guage included in an air line of a pump. If the guage is defective or if a pressure chart is inaccurate or has been misread, there is a danger of the tyre being over inflated with dangerous consequences.

According to the present invention, there is provided a valve for a pneumatic tyre comprising a body portion adapted to be located in an air passage of the tyre, the body portion including a bore, a valve seat, a member located in the bore and moveable to engage the seat and effect closure of the bore such as to restrain passage of air through the bore in an outward direction from the tyre and resilient means for urging the member to engage the seat wherein the resilient means provides sufficient force to effect closure of the bore only when pressure of the air in the tyre is less than a predetermined pressure.

Therefore, the resilient means will yield to pressure of air issuing from the tyre if in excess of the predetermined pressure. If the predetermined pressure is the prescribed pressure of the tyre, the valve in accordance with the invention will open to release excess air so that the tyre is at the correct air pressure.

Following is a description, by way of example only and with reference to the accompanying drawings, of one method of carrying the invention into effect.

In the drawings: Figure 1 is a longitudinal cross section of a known valve holder for receiving a valve in accordance with the present invention, Figure 2 is a longitudinal cross section of an embodiment of an outlet valve in accordance with the present invention.

Figure 3 is a diagrammatic cross section of a wheel and a tyre located thereon, the combination being provided with two valves one of which is as shown in Figure 2.

Figure 4 is a longitudinal cross section of an embodiment of an inlet valve.

Figure 5 is a longitudinal cross section of an embodiment of a combined two way inlet and outlet valve in accordance with the present invention, and Figure 6 is a diagrammatic cross section of a wheel and a tyre located thereon, the combination being provided with the valve as shown in Figure 5.

Referring now to Figure 1 of the drawings, there is shown a known valve holder 10 for a pneumatic tyre, the holder 10 comprising an elongate body portion 11 having a central longitudinal bore 12 an upper portion of which is of enlarged diameter and is threaded, as shown at 13. The body portion 11 is of enlarged bulbous configuration at a lower end portion thereof, as shown at 14.

Referring now to Figure 2 of the drawings, there is shown an embodiment of a valve 15 in accordance with the present invention. The valve comprises a cylindrical body portion 16 an outer surface of one end portion of which is threaded, as shown at 17. The body portion 16 is provided with a central longitudinal bore 18 which is of reduced diameter, as shown at 19, for a short distance extending inwardly from an end of the body portion 16 remote from the thread 17 and provides an inner conncave valve seat 20. The enlarged portion of the bore 18 has located therein a spherical valve member 21 which is moveable longitudinally of the bore 18. The enlarged portion of the bore 18 also has located thereon a coaxial helical compression spring 22 arranged such that the spherical valve member 21 is positioned between an inner end of the spring 22 and the valve seat 20. An outer end of the spring 22 is secured to a corresponding end of the body portion 16 by crimping the spring 22 on the body portion.

The spring 22 urges the valve member 21 against the valve seat 20 so that the valve 15 is normally closed. However, the characteristics of the spring 22 are such that the valve member 21 will move longitudinally of the bore 18 away from the valve seat 20 when there is a pressure differential in the bore 18 such that pressure of air in the portion 19 of reduced diameter exceeds the pressure of air in the enlarged portion of the bore 18 by a predetermined magnitude.

Referring now to Figure 3 of the drawings, the valve 15 is intended for use with a wheel 23 adapted to receive a tyre 24 and provided with two valve holders 10, 10', one 10' of which has located therein an inlet valve 25. The other of the valve holders 10 has located therein the valve 15, the threaded portion 17 of which engages with the thread 13 of the holder 10.

In use, the tyre 24 is inflated by connecting an air line to the inlet valve 25 and supplying air under pressure. When the pressure of air in the tyre 24 exceeds the predetermined magnitude, the pressure causes the valve member 21 to move away from the valve seat 20 thereby opening the valve 15 and releasing excess air so that the tyre 24 is at the predetermined air pressure.

The inlet valve 25 may be of a similar configuration to the valve 15, as shown in Figure 4, except that with the valve 25 an outer threaded portion 26 is located at an end of a body portion 27 of the valve 25 provided with a reduced diameter portion 28 of the longitudinal bore 29 and the helical compression spring 30 is of no specific strength.

Referring now to Figures 5 and 6 of the drawings there is shown an embodiment of the invention adapted for use with existing tyres and wheels. The embodiment is a two way inlet and outlet valve 31 comprising a cylindical body portion 32 having an external thread 33 at one end portion thereof. The body portion is of such dimension as to be receivable in a valve holder 10, the thread 33 being engagable with the thread 13 of the holder 10.

The body portion 32 is provided with a pair of spaced parallel longitudinal bores 34, 35 each having a portion of reduced diameter 36, 37 the reduced diameter portion 36 being located at an end portion of the body portion 32 provided with the thread 33 and the reduced diameter portion 37 being located at an end portion of the body portion 32 remote from the thread 33.

The enlarged diameter portions of the bores 34, 35 are provided with spherical valve members 38, 39 moveable longitudinally in the respective bores 34, 35 but urged against respective valve seats 40, 41 by corresponding helical springs 42, 43.

The arrangement is such that valve member 38 and the associated valve seat 40 and helical spring 42 comprise an inlet valve and the valve member 39 and associated valve seat 41 and helical spring 43 comprise an outlet valve. The characteristics of the helical spring 43 are such that, in use, the spherical member 39 is forced away from the corresponding seat 41 only when pressure of a gas forcing the spherical member 39 against the action of the spring 43 exceeds a predetermined magnitude.

Claims

1. A valve for a pneumatic tyre comprising a body portion adapted to be located in an air passage of the tyre, the body portion including a bore, a valve seat, a member located in the bore and moveable to engage the seat and effect closure of the bore such as to restrain passage of air through the bore in an outward direction from the tyre and resilient means for urging the member to engage the seat wherein the resilient means provides sufficient force to effect closure of the bore only when pressure of the air in the tyre is less than a predetermined pressure.

2. A valve as claimed in Claim 1 wherein the body portion comprises a pair of said bores each having located therein a corresponding one of a pair of said members each said member being urged against a corresponding seat by a corresponding one of a pair of said resilient means, the resilient means being arranged to urge the corresponding members in opposite directions against each corresponding seat.

3. A valve as claimed in Claim 1 or Claim 2 wherein the or each said member is spherical.

4. A valve as claimed in any one of the preceding Claims wherein the or each said resilient means comprises a compression spring.

5. A valve for a pneumatic tyre substantially as hereinbefore described and as illustrated in Figure 2 or Figure 5 of the accompanying drawings.