WO2001038150A1

WO2001038150A1 - Device for setting gas pressure levels

Info

Publication number: WO2001038150A1
Application number: PCT/GB2000/004502
Authority: WO
Inventors: David Daniel George Vile; Graham Dudley Eves
Original assignee: Transense Technologies PLC
Current assignee: Transense Technologies PLC
Priority date: 1999-11-25
Filing date: 2000-11-27
Publication date: 2001-05-31
Anticipated expiration: 2002-05-25
Also published as: GB2356704A; AU1647101A; GB9927739D0

Abstract

An aspect of the present invention provides a device for setting, to a desired level, the pressure of a gas held within a chamber, the device comprising an inlet (16) adapted to receive a gas for entry into said chamber; an outlet (18) connectable to said chamber; a transfer passage providing fluid communication between the inlet (16) and outlet (18); and a release valve (20) adapted to release, from the device, gas located in said transfer passage having a pressure greater than said desired level, the device being characterised in that the release valve (20) is moveable between at least two preset configurations wherein the configuration of the release valve (20) determines the level of pressure above which the release valve (2) releases gas from the device.

Description

DEVICE FOR SETTING GAS PRESSURE LEVELS

The present invention relates to a device for ensuring that gas pressure within a chamber is accurately set to desired, pre-determined levels. In particular, the present invention relates to a device that can be used for ensuring that pneumatic tyres of vehicles are correctly inflated to the appropriate levels of air pressure.

Vehicle users have found that air-line gauges at garages give a poor level of accuracy, which leads to errors in initially achieving and maintaining correct tyre inflation pressures. Often such gauges are dirty and difficult to use and read; and many users do not understand the difference between the alternative units of psi and bar.

Under-inflation of tyres can cause an increase in vehicle rolling resistance, thereby significantly increasing fuel consumption, road wear, noise emission and can also impair steering and braking performance. Indeed, the disparity between essential routine tyre maintenance required, and that generally practised, is a well known fact within the automotive industry, and road safety and environment agencies.

Pocket-sized, 'pencil' gauges are known with which to check tyre pressure, but such gauges are just measuring devices and cannot on their own be used to accurately set gas pressure to desired, pre-determined levels. Prior art documents US 3,807,432 and GB 2,197,476 A both disclose known devices for setting tyre pressures. Each of these known devices has a release valve which may be adjusted so as to allow the release of gas from the device at a desired pressure level. Each of the devices allows for adjustment of the release valve by means of the screw-threaded compression of a spring. However, a drawback with the use of these prior art devices is that a user must carefully adjust the release valve before use in order to ensure the correct inflation pressure is achieved. In the first of the aforementioned devices, no means for selecting a specific pressure is provided. In the second of the aforementioned devices, a calibrated scale is provided; however, although this allows a user to select many different pressure levels, the correct pressure level will only be selected provided the user is familiar with pressure scales and able to select the required pressure value. Also, even if the correct pressure level is set, the release valve of the prior art device can be unintentionally moved from the desired setting quite readily during use.

It is an objective of the present invention to provide a hand-held device that is very easy to use and which permits the user to set gas pressure very accurately to desired, pre-determined levels, without the need for battery or other external power sources.

Thus, in a first aspect, the present invention provides a device for setting, to a desired level, the pressure of a gas held within a chamber, the device comprising an inlet adapted to receive a gas for entry into said chamber; an outlet connectable to said chamber; a transfer passage providing fluid communication between the inlet and outlet; and a release valve adapted to release, from the device, gas located in said transfer passage having a pressure greater than said desired level, the device being characterised in that the release valve is moveable between at least two preset configurations wherein the configuration of the release valve determines the level of pressure above which the release valve releases gas from the device.

Accordingly, a device may be provided wherein a first preset configuration of the release valve corresponds to, for example, a pressure setting for the front tyres of a motor vehicle and a second preset configuration of the release valve corresponds to, for example, a pressure setting for the rear tyres of a motor vehicle. Thus, in use, an appropriate pressure setting may be accurately and readily selected simply by movement of the release valve to the appropriate preset configuration. The user is not required to interpret a calibrated pressure scale and therefore the risk of user error is reduced.

Although the chamber is typically a pneumatic tyre of a vehicle, any chamber that requires accurate setting of gas pressure of a gas contained therein is envisaged.

Further novel and advantageous features are set in subsidiary claims 2 to 17.

Preferably, the pre-determined level(s) of gas pressure are specific to the vehicle type, as specified by the vehicle manufacturer. Hence, each device will be specifically calibrated upon manufacture to be used only with a specific vehicle type, so that vehicles of different type will require differently calibrated devices and will typically be sold with the appropriate device already supplied.

In a particularly preferred embodiment, the pre-determined level of gas pressure can be set for tyres associated with different vehicle axles and/or different vehicle loadings. Thus, the device may be used to set the different pressures required for front and rear tyres respectively, as well as to set the different pressures required for normal and heavy vehicle loads.

According to a second aspect of the present invention, a set of such devices is provided wherein each device is calibrated to be capable of setting predetermined gas pressure levels different from those of other such devices.

In this way, a manufacturer of several vehicle types may manufacture the correspondingly calibrated devices as sets of devices, with each member of a set being supplied for use with a different (and appropriate) vehicle type.

The present invention, according to a third aspect, also provides use of such devices for increasing or decreasing gas pressure to a pre-determined desired level.

Thus, the device may be connected to both an air supply and a tyre so that air may be supplied to the tyre until the predetermined tyre pressure level is achieved. For example, the device may be connected to a front tyre and the device may be set to allow the tyre to be inflated to a pressure appropriate for heavy loads.

Alternatively, such a front tyre may be deflated by using the device with or without connection to an air supply, to assume a pressure appropriate for a normal vehicle load.

Further features of the present invention will be evident from the accompanying subsidiary claims and description below.

The present invention will now be described with reference to the following non-limiting embodiments, with reference to the accompanying drawings, in which:

Figure 1 shows a schematic representation of one embodiment of the device of the present invention; and

Figure 2 illustrates a second embodiment of the device of the present invention.

The schematic representation of Figure 1 shows an air inlet port (1) connectable to an air-line (not shown), the air inlet port (1) supplying air to a pressure relief valve (2). A manual selection switch (3) has an indicator with indicator marks, for example, for heavily loaded rear tyres (A'), normally loaded rear tyres (B'), heavily loaded front tyres (C) and normally loaded front tyres (D').

As the appropriate mark (A', B', C or D') on the indicator of the manual switch (3) is chosen, so the corresponding position (A, B, C or D) of a first spring (15) associated with the pressure relief valve (2) is adopted. The corresponding position of the first spring (15) sets a certain tension within the first spring (15), so that the pressure relief valve (2) can only open to allow air to flow through it, and to pass through a first non-return valve (4), when the pressure of the air within the pressure relief valve (2) is sufficient to overcome the tension in the first spring (15).

When the air pressure in the pressure relief valve (2) is insufficient to overcome the tension in the first spring, air passes through the pressure relief valve (2) through a second non-return valve (5) and on to an air outlet port (6), which can be connected to a chamber (not shown), such as a tyre. In this way, the first spring (15) may be set to a tension that represents a desired chamber air pressure. When the chamber air pressure is lower than that desired, that is, the chamber is under- inflated, air supplied from the inlet port (1) will flow through the pressure relief valve (2) and onwards to the outlet port (6) so as to enter the chamber and inflate it.

However, when the air pressure in the chamber reaches the desired level, any further air supplied from the inlet port (1) will cause pressure in the pressure relief valve (2) to be sufficient to overcome the tension in the first spring (15), thus allowing the further air to be vented away from the chamber through the first non-return valve (4).

As different tensions can be set for the first spring (15), correspondingly different air pressures may be set within the chamber. Thus, if the first spring (15) is set to position A, the chamber will be set, if it is a tyre, to an air pressure suitable for. a heavily loaded rear vehicle tyre. However, if the first spring (15) is set instead to position D, then the chamber will be set to a pressure suitable for a normally loaded front vehicle tyre.

Although Figure 1 shows the pressure relief valve (2) operating by way of a first spring (15), any suitable means can be used that is capable of (a) setting relief pressures above which the valve (2) can open and so allow gas to be vented away from the chamber; and (b) setting relief pressures below which the valve (2) can remain closed and so allow gas to inflate the chamber via the outlet port (6).

Figure 1 also shows a 'correct inflation' indicator (7), which is connected to receive gas passing through the first non-return valve (4) via an entry port (9). A piston (11) is biased towards the entry port (9) by a second spring (10).

When the chamber has been inflated to the correct pressure, further air supplied from the inlet port (1) opens the pressure relief valve (2), so that air is supplied through the first non-return valve (4) and into the 'correct inflation' indicator. Thus pressurised air acts upon the piston (11) with a resultant force that overcomes the tension in the second spring (10) and the piston (11) moves until air can escape through a venting port (12) and so out of the device through a vent (8). The escape of air causes a reduction in pressure within the 'correct inflation' indicator (7) and so tension in the second spring (10) returns the piston (11) back to its original position towards the entry port (9). Further air entering the entry port (9) causes the piston (11) to retract again until air can pass once more through the venting port (12). And so the cycle of increasing and decreasing air pressure within the 'correct inflation' indicator (7) results in a rapid backward and forward movement of the piston rod (13), thus providing a readily audible, visible and tactile warning to the user as an indication that correct inflation has been reached.

In Figure 2, an enlarged cross-sectional view of a pocket-sized device according to the scheme described above is illustrated.

In this embodiment a device is provided with an inlet port (16) for passing gas through a first non-return valve (17) and through an outlet port (18) when a pressure relief valve (20) is in a closed position (as shown). The outlet port (18) of the device may be attached to the inflation valve of a pneumatic tyre such that a depression pin (32) of the outlet port (18) mechanically holds open the tyre's nonreturn valve (not shown). Further, the inlet port (16) may be connected to an air supply line, so that the tyre can be inflated when the pressure relief valve (20) is in a closed position.

When the air pressure within the tyre reaches the desired, predetermined level, further air supplied causes an increase in pressure within the pressure relief valve (20), which consequently opens when the pressure is sufficient to overcome the tension in a first spring (21) within the valve (20). As the tension in the first spring (21) is overcome, closure means of the valve (20) moves away from its seat (19) against which it was previously biased by the first spring (21).

With the pressure relief valve (20) now in its open position, further air passes from the inlet port (16) through the valve (20) and up a vent (27) into a compartment (28) associated with an indicator valve (29). However, air does not pass out of the tyre, since the pressures at the outlet port (18) and tyre are equal.

The indicator valve (29) has a second spring (30) which is of lower tension bias than the first spring (21). Thus, as air vented into the compartment (28) increases the pressure within the compartment (28), the second spring (30) is compressed and the indicator valve (29) opens. As the indicator valve (29) opens, air pressure within the compartment (28) reduces and the second spring (21) resumes its former position with the indicator valve (29) closing. Subsequent increase in pressure within the compartment (28) opens the indicator valve (29) once again, and so a cycle of opening and closing of the indicator valve (29) continues so long as air passes through the vent (27).

The oscillation of the indicator valve (29) provides the user of the device with an audible, visual and tactile signal that the desired, pre-determined tyre pressure has been achieved.

The device can be pre-set to allow the inflation of the tyre to anyone of several pre-determined, desired pressures. This is achieved by pre-setting the tension in the first spring (21) by manually setting an adjustment cap (23) of the device by rotation of the cap (23). The cap (23) is connected to a unit (22) that can compress the first spring (21) by calibrated increments. The increments are calibrated on the unit (22) by indents (A', B', C and D'), which each represent specific spring (21) tensions and so represent specific, desired tyre pressures.

By rotating the cap (23), the user rotates a helical nut about a helical screw (26) within the cap (23), so causing axial movement of the unit (22) longitudinally down the device and so compressing the first spring (21). An anti- rotation pin (25) prevents the unit (22) from rotating, so that the rotational movement of the cap (23) is translated into linear movement of the unit (22).

As the cap (23) is rotated, the user will match up external markings on the cap (23) to give the device a pre-set position, which corresponds to a position in which one of the indents (A', B', C or D') is positively engaged with an engagement means (24) to help lock the setting of the first spring's (21) compression.

As an alternative to the shown cap (23) with its helical internal arrangement, a simple push/pull system with an external indicator of settings may be used to set the first spring (21) compression.

In use, the device may be connected via its inlet port (16) to an air supply line and via its outlet port (18) to the inflation valve of a tyre. The correct setting of the device can be made by rotating the cap (23) and then air may be passed into the tyre until the indicator valve (29) indicates that the desired, pre- determined tyre pressure has been achieved.

If the tyre has been set to a pressure appropriate for a heavy vehicle loading, the vehicle user may wish to revert the pressure to one appropriate for normal loads once the load has been removed from the vehicle. Thus, the user will attach the device to the tyre via its outlet port (18), having pre-set the rotation of the cap (23) to the setting appropriate with normal loads and the axle upon which the tyre is located. When outlet port (18) is attached to the tyre, the depression pin (33) opens the tyre's non-return valve (not shown) and air can escape from the tyre through the outlet port (18). Once the tyre has been deflated to the desired level, the indicator valve (23) will cease to make an indicating sound.

Each device can be tailored for a specific vehicle type and may be identified accordingly. Typically, it may form an essential constituent of the tool kit supplied by the manufacturer when the vehicle is made.

Machining of calibrated indents (A', B', C and D') can be achieved with a great degree of accuracy. Thus, by factory setting the pressure relief valves of such devices, manufacturers can provide devices with an accuracy of greater than 2% (0.5 psi at 30 psi). In contrast, the best accuracy observed for pressure gauges located in commercial tyre replacement outlets is typically +/- 2 psi at 28psi, or 14%, and the accuracy of garage forecourt pressure gauges is often much worse.

In addition, the devices can be machined so as to have a robustness that will ensure that they remain accurate throughout their projected life, typically 10 years.

Hence, the present invention provides users with an accurate method of being able to inflate and maintain gas pressure within a chamber, for example a pneumatic tyre, at the correct inflation pressures. The device of the invention is very easy to use and requires no complicated readings to be made. Indeed, the predetermined settings of the device are usually factory set and fixed for the life of the device.

The device allows users to easily and accurately set increased tyre pressures for heavy load carrying or for tyres located on different axles. Further, the device may be a hand-held, conveniently sized tool and requires no battery or other external source of power.

Claims

CLAIMS:

1. A device for setting, to a desired level, the pressure of a gas held within a chamber, the device comprising an inlet (16) adapted to receive a gas for entry into said chamber; an outlet (18) connectable to said chamber; a transfer passage providing fluid communication between the inlet (16) and outlet (18); and a release valve (20) adapted to release, from the device, gas located in said transfer passage having a pressure greater than said desired level, the device being characterised in that the release valve (20) is moveable between at least two preset configurations wherein the configuration of the release valve (20) determines the level of pressure above which the release valve (2) releases gas from the device.

2. A device as claimed in claim 1, wherein registration means (24,A',B'_.C',D') is provided for positively locating the release valve (20) in one of said preset configurations.

3. A device as claimed in claim 2, wherein the registration means (24,A',B'_.C',D') comprises means for biasing the release valve (20) towards a preset configuration.

4. A device as claimed in claim 3, wherein the biasing means is adapted so that, once the release valve (20) is located in a preset configuration, a movement from said preset configuration is resisted.

5. A device as claimed in any of claims 2 to 4, wherein the registration means (24,A',B',C',D') comprises two members which move relative to one another when the release valve (2) moves between preset configurations and which abut one another so as to resist said relative movement when the release valve (20) locates in a preset configuration.

6. A device as claimed in claim 5, wherein one of said members of the registration means (24,A',B',C',D') is biased against a camming surface of the other of said members.

7. A device as claimed in claim 6, wherein said biased member is a ball.

8. A device as claimed in claim 6 or 7, wherein said camming surface comprises a detente in which said biased member is received when the release valve (20) locates in a preset configuration.

9. A device as claimed in any of the preceding claims, the device further comprising an indication means (29) adapted to indicate to the user of the device an occurrence of gas being released from the device through the release valve (20).

10. A device as claimed in claim 9, wherein the indication means (29) comprises a compartment (28) connected to the release valve (20) via a vent (27) such that gas in said transfer passage which is released through the release valve (20) is so released to the compartment (28) via the vent (27), the compartment (28) comprising a further valve (30) adapted to oscillate between open and closed positions, when gas is released from the chamber, so as to release pulses of gas out of the device.

11. A device as claimed in claim 10, wherein the further valve (30) emits an indicating sound as it oscillates between open and closed positions so as to indicate to the user of the device that gas is being released from the device.

12. A device as claimed in any of the preceding claims, wherein the release valve (20) comprises a seat (19), closure means and resilient means (21), whereby, in a closed position, the closure means is biased against the seat (19) by the resilient means (21) so as to prevent gas from passing through the release valve (20) and, in an open position, gas located in said transfer passage has pressure sufficient to force the closure means away from the seat (19) so as to allow gas to pass through the release valve (20).

13. A device as claimed in claim 12, further comprising adjustment means adapted to vary the biasing force exerted by the resilient means (21) on the closure means and thereby permit location of the release valve (20) in a preset configuration.

14. A device as claimed in claim 13, wherein the adjustment means comprises a unit (22) for compressing the resilient means (21) against the closure means, the unit (22) being adapted to be positioned within the device, for a given preset configuration of the release valve (20), such that the resilient means (21) is compressed so as to exert a pre-determined biasing force on the closure means.

15. A device as claimed in any of the preceding claims, wherein the preset configurations of the release valve (20) provide gas release at gas pressures required for the correct inflation of a pneumatic tyre as specified by a vehicle manufacturer in respect of a specific vehicle type.

16. A device as claimed in claim 15, wherein the preset configurations of the release valve (20) provide gas release at gas pressures required for the correct inflation of tyres associated with different vehicle axles or different vehicle loads.

17. A device as claimed in any of the preceding claims, wherein the desired level of gas pressure can be set with an accuracy of +/- 2%.

18. A set of devices comprising two or more of the devices claimed in any of the preceding claims, wherein each device is calibrated to be capable of setting predetermined desired gas pressure levels different from those of the or each other device.

19. Use of a device as claimed in any of claims 1 to 17 for increasing or decreasing gas pressure in a chamber to a pre-determined desired level.

20. A device, use of such a device, or set of such devices substantially as hereinbefore described with reference to, and/or as illustrated in, the accompanying drawings.