GB1589217A - Tyre valves - Google Patents

Description

(54) IMPROVEMENTS IN OR RELATING TO TYRE VALVES (71) We, SCOVILL INC. formerly known as Scovill Manufacturing Company, a corporation organised under the laws of the State of Connecticut, United States of America, having a place of business at 829 Tyburn Road, Erdington, Birmingham 24, 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: The present invention relates to tyre valves for use with tubed tyres, as used for example on commercial vehicles such as trucks and buses.

Valves are generally provided with a rubber base or spud by means of which the valve is secured to a rubber inner tube over an aperture therein. Valves of different lengths are required for use with different wheels and a range of different size valves is provided by the manufacturer. To this end, "universal" valves are well known which have a short tubular base or spud secured to a tyre inner tube with an extension stem containing a valve core, which can be screwed onto the base. Extension stems of different lengths and shapes can thus be attached as desired depending on the size and requirement of the rim configuration.

The extension stem can only be attached when the inner tube is removed from the rim.

According to the present invention there is provided a valve for a tyre inner tube, the valve including a tubular base or spud for securing to the tyre tube, an extension stem removably attached to said base or spud and containing a first valve core, an auxiliary stem removably attached by a screw-thread to the said extension stem and containing a second valve core, the auxiliary stem having means for operating the first valve core and being provided with a skirt surrounding a portion of the extension stem, a sealing ring being positioned between the extension stem and the skirt of the auxiliary stem so that sealing between the two stems by said ring is attained before there is full engagement of the screw-threaded attachment between the stems during assembly.

The sealing ring is preferably disposed in a groove in the external surface of the extension stem.

Preferably the means for operating the first valve core is a projection extending within the screw-threaded portion of the auxiliary stem so as to contact a pin of the first valve core and displace it to hold the first valve core open when the auxiliary stem is fully engaged with. the extension stem. The projection is suitably shaped so as to contact and displace the pin while not obstructing an air flow passage through the extension stem and auxiliary stem.

Alternatively the means for operating the first valve core may be a member extending within the auxiliary stem from the second valve core and being displaceable by a pin of the second valve core so as to contact and displace the pin of the first valve core to hold the first valve core open when the second valve core pin is itself displaced to open the second valve core.

Preferably the extension stem is screwthreaded for its removable attachment to the tubular base or spud secured to the tyre tube.

Particular embodiments of the invention will now be described by way of example only with reference to the accompanying drawings in which: Fig. 1 is a partly cross-sectional view of a valve according to the invention, and Fig. 2 shows the valve core and projl:cting member core for a modified embodiment of auxiliary stem.

The valve shown in Fig. 1 has a rubber spud or base 10 for bonding to a tyre inner tube, in which is embedded an end flange 12 of a short duct 14. A cranked brass extension stem 16 is internally screw-threaded at an inner end 17 to be secured to mating external screw-threading of the duct 14. A flange 18 is provided on the same end of the stem and presses a soft rubber washer 20 against the rubber base 10 when the stem is fully screwed onto the duct, in order to seal the joint between the stem and the spud.

At its outer end, the extension stem is externally screw-threaded at 21 and adjacent this end of the stem a first valve core (not shown) of conventional design is disposed within the stem, with its pin arranged to be operated from the outer end of the stem.

In these respects the extension stem corresponds to a conventional universal valve.

It is however further provided with a circumferential groove for engagement of a sealing ring 22 below the threaded end 21.

Also, an auxiliary stem 24 is internally screw-threaded at 26 to mate with the screwthread 21 on the valve stem. The auxiliary stem has a depending skirt 28 below the screw-thread 26 which surrounds the extension stem 16 and slidably engages the sealing ring 22 to seal thd joint between the extension stem and the auxiliary stem as they are screwed together.

A second valve core (not shown) also of conventional design is disposed within the auxiliary stem adjacent the outer end thereof and with its pin operable from the outer end of the auxiliary stem. The auxiliary stem 24 also has a projection 32 extending longitudinally within its bore at its inner end in the region of the screw-threaded portion 26.

The projection 32 is positioned so that it will contact and depress the pin of the first valve core as the auxiliary stem is fully screwed onto the extension stem and is shaped and disposed so that it allows free passage of air between the two stems. A sealing washer 34 is provided in the auxiliary stem 24 to seal against the end of the extension stem 16, and the projection 32 may be a machined part trapped between a shoulder 36 and the washer 34, or it may be integral with the extension stem 24. The outer end of the auxiliary stem 24 is externally screwthreaded at 29 to receive a dust-cap 30.

The extension stem is bent through an angle la at a predetermined distance H from the base. For current uses the angle it may be 86" and the distance H may be 13/1G" (20.5 mm). The operative length B of the stem, in conventional valve stems, has to be sufficient to extend through the rim aperture of the particular wheel involved. For a given distance H, B is determined by the total length of the extension stem. In conventional valves, various stems of different lengths are manufactured to meet the demands of different uses. The lengths may vary, e.g. between 3-4" and 6ll/32''. The length of the auxiliary stem for a valve according to the invention is chosen to give a valve of desired overall length, and the manufacturer can supply a number of inter changeable auxiliary stems of varying lengths. By selecting the stem it is possible to ensure easy accessibility to the tyre valve for a vehicle operator, so assisting in avoidance in problems of tyre damage that have occurred on commercial vehicles where tyres have been left uninflated because the valve was inaccessible, particularly on the inner wheel of a twin formation.

In use an auxiliary stem 24 of selected length is placed over the end of an extension stem 16, in situ, so that a seal is formed between them by the ring 22. As the auxiliary stem is pushed onto the extension stem (the inner surface of the skirt 28 moving across the sealing ring 22) the screwthreaded portions 21, 26 can be engaged.

As the auxiliary stem 24 is then screwed onto the extension stem 16 the projection 32 comes into contact with the pin of the first valve core in the valve stem, depresses and opens it. When fully engaged the washer 34 seals against the top of the extension stem 16. The valve in the stem 16 is thus fully open when the auxiliary stem is in position and air pressure in the tube can be tested by operation of the second valve core pin adjacent the outer end of the auxiliary stem 24. The presence of ring 22 prevents leakage of air during positioning of the auxiliary stem and also retains a seal as the auxiliary stem is removed. It has the further function of acting as a vibration damper and will maintain a seal even if the threaded portions become loose during use.

When the auxiliary stem 24 is removed the first valve core will close in the stem 16, preventing loss of pressure, e.g. during replacement of a damaged stem 24. Since it is the second core that is used for inflating and testing of the tyre pressure it is this valve core that is likely to become damaged in use, and if this happens repair is made simply by unscrewing the auxiliary stem 24 and replacing with a new one. This replacement can be done without needing to remove the wheel or even to deflate the tyre.

An alternative embodiment of auxiliary stem 24 may be without the projection 32 but is provided with a second valve core 38 as shown in Fig. 2. The second valve core here has a further member 40 projecting from it and of a length so that it contacts the pin of the first valve core to depress said pin and open the first valve core in the stem 16 only when the pin of the second valve core 38 is depressed for inflation or pressure testing. Should the first valve core leak the tyre pressure will be contained by the O-ring seal 22 and the second core 38 which acts as a sealing core. Again replacement is simply a matter of unscrewing the auxiliary stem 24 and screwing on a new one.

The auxiliary stem may be made of metal or plastics, but metal is preferred.

It can be seen the valves of the present invention offer advantages in accessibiiity through choice of length and easy replacement of a damaged extension stem or auxiliary stem. Improvements in stock control are possible since it is only necessary to stock various sizes of extension stems and auxiliary stems to adapt a tyre tube to different specific end uses.

Furthermore the seal provided by the sealing ring between the skirt of the auxiliary stem and the extension stem is particularly effective and tests have shown that leaks do not occur even after prolonged use. This is particularly important in those valves where the valve core in the extension stem is held open. Even in valves where the valve core is not intended to be held open, e.g. in Che use of the embodiment of Fig. 2, it can happen that the core in the extension stem is in fact opened, so that an efficient seal within the skirt of the auxiliary stem is is important here also. Even if the auxiliary stem should become loosened on the extension stem it will not lose the air-tight seal, due to this particular sealing arrangement.

WHAT WE CLAIM IS:- 1. A valve for a tyre inner tube and including a tubular base or spud for securing to the tyre tube, an extension stem removably attached to said base or spud and containing a first valve core, an auxiliary stem removably attached by a screw-thread to the extension stem and containing a second valve core, the auxiliary stem having means for operating the first valve core and being provided with a skirt surrounding a portion of the extension stem, a sealing ring being positioned between the extension stem and the skirt of the auxiliary stem so that sealing between the two stems by said ring is attained before there is full engagement of the screw-threaded attachment between the stems during assembly.

2. A valve according to claim 1 wherein the sealing ring is disposed in a groove in the external surface of the extension stem.

3. A valve according to claim 1 or claim 2 wherein a further sealing ring is provided to seal between the auxiliary stem and the end of the extension stem when the auxiliary stem is fully engaged with the extension stem.

4. A valve according to any one of claims 1 to 3 wherein the means for operating the first valve core is a projection extending within the screw-threaded portion of the auxiliary stem so as to contact a pin of the first valve core and displace it to hold the first valve core open when the auxiliary stem is fully engaged with the extension stem.

5. A valve according to any one of claims 1 to 3 wherein the means for operating the first valve core is a member extending within the auxiliary stem from the second valve core and being displaceable by a pin of the second valve core so as to contact a pin of the first valve core and displace it to hold the first valve core open when the second valve core pin is displaced to open the second valve core.

6. A valve according to any one of the preceding claims wherein the extension stem has a screw-thread by which it is removably attached to the tubular base or spud.

7. A valve for a tyre inner tube constructed and arranged substantially as described herein with reference to Fig. 1 or Fig. 2 of the accompanying drawing.

8. A tyred vehicle wheel provided with a valve according to any one of the pre

Claims (1)

1. ceding claims.