AU734906B3

AU734906B3 - Pressure relief valve

Info

Publication number: AU734906B3
Application number: AU38804/01A
Authority: AU
Inventors: Stephen John Furlonger; Vaughan Grant
Original assignee: STAUN Pty Ltd
Current assignee: STAUN Pty Ltd
Priority date: 2001-04-23
Filing date: 2001-04-23
Publication date: 2001-06-28
Anticipated expiration: 2007-04-23

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A PETTY PATENT Name of Applicant: Actual Inventor: Address for Service: Invention Title: VAUGHAN GRANT and STEPHEN JOHN

FURLONGER

VAUGHAN GRANT and STEPHEN JOHN

FURLONGER

CULLEN

CO.,

Patent Trade Mark Attorneys, 239 George Street, Brisbane, QId. 4000, Australia.

PRESSURE RELIEF VALVE The following statement is a full description of this invention including the best method of performing it known to us: PRESSURE RELIEF VALVE TECHNICAL FIELD This invention relates to pressure relief valves and has particular relevance to valves suitable for lowering pressures within pneumatic tyres.

s BACKGROUND ART It is important for motorists to regularly check that tyre pressures are even and in accordance with the specified pressures for particular driving conditions and circumstances.

Most service stations provide a free air service where motorists io are able to check their air pressures and if necessary make adjustments to same.

Whilst increasing tyre pressures is a relatively straight forward matter, reducing pressures to a required level requires the motorist to depress the needle of a two way valve of each tyre to allow air to bleed and then to recheck with a pressure gauge that an appropriate pressure has been reached.

Most four-wheel drive and terrain vehicles are designed to be driven in off road situations with lower than normal tyre pressures.

Because the off road usages are generally in remote areas where air pumps and gauge facilities are unlikely to be available, it is necessary for the vehicle driver to manually bleed off air from each tyre and to constantly check with a gauge the status of each tyre during the process.

It is easy for a motorist in these circumstances to inadvertently reduce the pressure to below the required rate. It would be convenient in these circumstances for motorists to have available a pressure relief valve which can be applied to the valve of each tyre of his vehicle and which ensure that the exact lower tyre pressure he requires is achieved accurately without the danger of deflation below an acceptable level.

In our Australian Petty Patent no.719902 we describe a pressure relief valve which can be pre-set and attached to a two-way valve of a vehicle tyre so that air is bleed from a tyre past a piston within the valve.

Whilst this particular relief valve has proven to be of value in general usage, in some instances, particularly for vehicles with larger tyres it is desirable that the bleed off of air be achieved in a shorter time span.

It is an object of the present invention to provide a pressure relief valve which can be applied to the valve of a pneumatic tyre and which will allow expeditious and accurate deflation of tyres to a predetermined level.

Further objects and advantages of the present invention will become apparent on the ensuring description which is given by way of example.

DISCLOSURE OF INVENTION LO According to the present invention there is provided a pressure relief valve comprising; (a) (b) (c) a substantially elongate valve body having an internal air bleed chamber, an adjacent air bleed passage and a tyre valve engagement means, a cap adjustably attached to an open end of the air bleed chamber, the said air bleed chamber and cap having complimentary external and internal threads, a piston within the air bleed chamber said piston having a valve head which is adapted to engage with a valve seat located between the air bleed chamber and the air bleed passage, an air bleed hole in the valve body above the valve seat, a biasing spring mounted within the air bleed chamber which is compressed between the cap and the valve head and applies a continuous closing bias to the piston, and a strike pin extending from the tyre valve engagement means the arrangement and construction being such that when the valve body is coupled to a two-way valve of a pneumatic tyre and the strike pin contacts a needle within the twoway valve pressures within the tyre can be reduced via the air bleed valve in proportion with a predetermined compression applied to the spring which can be adjusted according to the degree that the cap is advanced on the air bleed chamber thread.

The valve can include an internally threaded lock washer mounted on the bleed chamber thread beneath the cap.

BRIEF DESCRIPTION OF THE DRAWINGS Aspects of the present invention will now be described by way of example only with reference to the accompanying drawings in which; Figure 1 is a bottom view of a pressure relief valve in accordance with one aspect of the present invention, and Figqure 2 is a side view of a pressure relief valve of Figure 1, and Figqure 3 is a plan view of the pressure relief valve of Figure 1, and Fi.qures 4 and 4a are full and partial cross sections respectively of the valve of the present invention taken at IV:IV of Figure 3.

With respect to the drawings a pressure relief valve in accordance with the present invention can comprise a substantially elongate valve body generally indicated by arrow 1 having an internal bleed chamber 2 and adjacent air bleed passage 3 and tyre valve engagement means 4.

The valve body is provided with a cap 5 which is adjustably mounted to an open end of the air bleed chamber 2.

A valve generally indicated by arrow 6 is disposed centrally within the air bleed chamber said valve having a valve head 7 which is adapted to engage and seal a valve seat 8 located between the air bleed chamber 2 and the air bleed passage 3. The valve is a cup-shaped member and comprises a base 9, sidewalls 9a and a resilient sealing member A biasing compression spring 11 is mounted within the valve and the spring is compressed between the cap 5 and the valve head 7 and applies a constant closing bias to the valve.

At the base of the air bleed chamber 3 there is provided one or more air passages 12 are provided and a centralised strike pin 13 extends outwardly the arrangement and construction being such that when the valve body 1 is coupled to a two way valve 14 and the strike pin 13 contacts the needle 15 of the valve pressures within the tyre (associated with the valve 14) cap be reduced in proportion compression applied to the spring.

The air bleed chamber 2 and the cap 5 have complimentary external and internal threads 16 so that the position of the cap and thus the pressure on the spring can be adjusted to predetermined levels.

A locking washer 17 can also be fitted to the thread 16 to secure the cap in its desired position.

As the cap is wound off the thread 16 a predetermined distance pressure on the spring 11 is reduced accordingly. The surfaces of the thread and/or body or cap be marked to assist the user to select pressure ranges for the position and therefore the pressure on the compression spring can be adjusted by the use of a gauge or the like equating the distance S from with specific pressures.

The internal walls of the engagement means 4 can be provided with a standardised internal thread 4a which matches with the standard external thread of a two way valve.

The body 1 of the valve can be moulded or fabricated or machined from metal or plastics.

Air which is bleed from a tyre will enter the bleed passage and 9 apply pressure to the underside of the valve. The internal bore of the bleed chamber 2 and the sides 9a of the valve 6 are of close tolerances in a manner similar to the pistons and bores of a combustion engine. A short distance above the valve seat 9 a bleed hole or aperture is provided and when the base 9 of the valve 6 rises above the bleed hole air can be bleed expeditiously via the relief valve.

In the event that some air leaks past the valve 6 a further bleed hole 19 in the top wall of the cap 5 will be vented via the aperture 19.

The underside of the top wall of the cap 5 can be provided with centering member to ensure the compression and expansion of the spring is linear.

The present invention allows accurate adjustment of tyre pressures, can be readily preset the user and reduce pressures in tyres can be elevated by the user by simply removing the relieve valves and re-inflating the tyres.

Aspects of the present invention have been described by way of example only and it will be appreciated that modifications and additions thereto may be made without departing from the scope thereof as defined in the appended claims.

Claims

1. A pressure relief valve comprising; a substantially elongate valve body having an internal air bleed chamber, an adjacent air bleed passage and a tyre valve engagement means, a cap adjustably attached to an open end of the air bleed chamber, the said air bleed chamber and cap having complimentary external and internal threads, a piston within the air bleed chamber said piston having a valve head which is adapted to engage with a valve seat located between the air bleed chamber and the air bleed passage, an air bleed hole in the valve body above the valve seat, a biasing spring mounted within the air bleed chamber which is compressed between the cap and the valve head and applies a continuous closing bias to the piston, and a strike pin extending from the tyre valve engagement means the arrangement and construction being such that when the valve body is coupled to a two-way valve of a pneumatic tyre and the strike pin contacts a needle within the two- way valve pressures within the tyre can be reduced via the air bleed valve in proportion with a predetermined compression applied to the spring which can be adjusted according to the degree that the cap is advanced on the air bleed chamber thread.

2. A pressure relief valve as claimed in claim 1 having an internally threaded lock washer mounted on the bleed chamber thread beneath the cap.

3. A pressure relief valve as claimed in claim 1 or claim 2 and substantially as herein described with reference to the accompanying drawings. DATED this 23rd day of April 2001 VAUGHAN GRANT and STEPHEN JOHN FURLONGER By their Patent Attorneys CULLEN CO.