GB2089297A

GB2089297A - Tyre pressure regulators

Info

Publication number: GB2089297A
Application number: GB8134644A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1980-12-12
Filing date: 1981-11-17
Publication date: 1982-06-23

Abstract

A tyre pressure regulator comprises a housing 1a- 1b adapted to be secured to the hub of a wheel carrying a pneumatic tyre so as to rotate therewith, a counterweight 8 journaled within the housing so as to permit the housing to rotate relative to the counterweight about the axis of the wheel, a pneumatic pump assembly secured within the housing and consisting of a disc 9 with opposed cylinders 11a, 12a containing pistons 11, the counterweight having a cam portion 7 which co-operates with followers 14 on the pistons to reciprocate the latter and effect pump action on rotary movement between the pump assembly and counterweight during rotation of the wheel, and a pressure regulator valve arrangement operative to ensure that air from the pump assembly is supplied to the pneumatic tyre at a predetermined pressure. <IMAGE>

Description

SPECIFICATION Improvements in or relating to tyre pressure regulators This invention relates to tyre pressure regulators suitable for use with automobiles, by means of which tyre pressure is regulated automatically while a vehicle is in motion.

According to the present invention the tyre pressure regulator comprises a housing adapted to be secured to the hub of a wheel carrying a pneumatic tyre so as to rotate therewith, a counterweight journaled within the housing so as to permit rotary movement between the housing and the counterweight about the axis of the wheel, pneumatic pump means secured within the housing, the counterweight being adapted to co-operate with the pump means in response to rotary movement between the counterweight and the pump means produced consequent upon rotation of the wheel so as to effect pump action, and pressure regulator valve means operative to ensure that pressurised air from the said pump means is supplied to the pneumatic tyre at predetermined pressure.

The adaptation of the counterweight as aforesaid may comprise a cam which is secured to the counterweight to form a unit, the pump means including cam follower means, the cam follower means being operatively associated with the cam for driving the said pump means in response to rotary movement between the cam follower means and the cam, produced consequent upon rotation of the wheel.

In operation of the tyre pressure regulator the cam and counterweight unit which is journalled in the housing so as to hang on its bearings, will due to its mass, tend to remain stationary, whilst the pump means rotates about it as the wheel rotates. The cam follower means thus reacts against the cam to drive the pump which feeds the tyre with compressed air via the regulator valve means so as to inflate the tyre when the pressure therein falls below the predetermined value, excess pressure being vented to atmosphere.

The housing may be adapted to clip onto the wheel so as to serve as a hub cap.

The housing may comprise an outer body and a back plate, the back plate being secured to the outer body so as to define therebetween a compartment in which the pump means and the counterweight are received.

The counterweight and cam unit may be journalied in a bearing which is fitted in the outer body and the pump means may be secured to the back plate.

The pump means may comprise at least one piston which is arranged to be driven by the cam via the cam follower means.

Two diametrically opposed pistons may be provided and one end of each piston may be adapted to receive a ball which serves as a cam follower, the other end of each piston being formed with a groove to receive a piston ring which provides a seal against the walls of a cylinder or barrel in which it is received.

The pump means may comprise an annular disc formed to provide two diametrically opposed cylinders or barrels in which the pistons are received, the cam being arranged to project into the centre aperture of the annular disc and to co-operate with the balls at the ends of the pistons, the balls being biased against the cam by biasing means contained within the cylinders or barrels which act on the ends of the pistons remote from the balls.

The biasing means may comprise springs which may be fitted in recesses in the crowns of the pistons.

At the end of each cylinder remote from the pistons, inlet valve means may be provided via which air is admitted to the cylinder, but via which air above atmospheric pressure cannot escape.

The inlet valve means, which may be ball valves, may be fed from atmosphere via an inlet filter contained in a passageway within the annular disc.

At the end of each cylinder or barrel remote from the pistons, there may also be provided an outlet passageway which communicates with the tyre via the said pressure regulator valve means.

The pressure regulator valve means may comprise an adjustable valve within each outlet passageway and an adjustable pressure limiting valve which is positioned outside the compartment, the adjustable valves being set to pass to the tyre air from the pump means only if it exceeds a preset tyre pressure, and the pressure limiting valve being set to determine the maximum pressure of air in the tyre.

The pressure limiting valve may be provided with a pressure regulating control which projects through the outer body so as to facilitate adjustment after the tyre pressure regulator has been fitted to a wheel.

The tyre pressure regulator may be fitted with an inlet valve which communicates with the outlet passageways and by means of which the tyre may be inflated from an external compressor.

One embodiment of the invention will now be described by way of example with reference to the accompanying drawings wherein corresponding parts of the various Figures bear where appropriate the same numerical designations and, in which: Figure 1 is a sectional side view of a wheel having fitted thereto a tyre pressure regulator; Figure 2 is a sectional side view of the pressure regulator of Fig. 1 but showing greater detail; Figure 3 is a part perspective view of a part of the body of the pressure regulator; Figure 4 is a part perspective view of a back plate of the pressure regulator shown in Figs 1 and 2; Figure 5a is a front elevation of a counterweight forming part of the pressure regulator of Figs 1 and 2; Figure 5b is a sectional side view of the counterweight shown in Fig. 5a;; Figure 5c is a sectional side view of a needle roller bearing on which the counterweight is journalled; Figure 6a is a perspective view of the counterweight; Figure 6b is a perspective view of a cam forming part of the counterweight and in which the bearing shown in Fig. 5 C is fitted; Figure 7a is a perspective view of the cam shown in Fig. 8b; Figure 7b is a perspective view of the bearing shown in Fig. 5c; Figure 7c is a perspective view of a spindle on which the bearing shown in Figs Sc and 7b is mounted; Figure 8 is a perspective view of a piston and barrel disc assembly forming part of the pressure regulator shown in Fig. 2; Figure 9 is a part sectional elevation of the piston and barrel disc assembly shown in Fig.

8; Figure 10 is a sectional side view of the piston and barrel disc assembly shown in Fig.

9; Figure 11 is an exploded sectional view of a part of the piston and barrel disc assembly showing the parts of the piston and barrel; Figure 12 is a sectional side view of a pressure regulator valve 23 shown also in Fig.

1; Figure 13 is a further sectional view of the regulator valve shown in Fig. 12; and Figure 14 is another sectional view of the regulator valve 23 shown in Fig. 12.

Referring now to the drawings, a tyre pressure regulator comprises a housing 1 which is arranged to clip onto the hub 2 of a wheel carrying a pneumatic tyre 3. As shown in Fig.

2 the housing comprises an outer cover 1 a, which is secured by means of screws 1 cto a back plate 1 b. The general appearance of an outer cover 1 a and the back plate 1 b can be seen most clearly from Figs. 3 and 4. As can be seen clearly in Fig. 2 the outer cover 1 a and the back plate 1 b fit together to provide a compartment 4. Fitted within the compartment 4 to the cover 1 a and aligned with the wheel axis, there is provided a spindle 5 which projects into the compartment 4 and has mounted thereon a needle roller bearing 6 for rotation about the spindle 5. Fitted over the needle roller bearing 6 there is provided a cam 7 which is fitted to and forms a part of a counterweight 8.

The cam 7, the spindle 5, the needle roller bearing 6 and the counterweight 8 are most clearly seen in Figs 5a, Sb, 5c, 6a, 6b, 7a, 7band 7c.

Fitted to the back plate 1 b there is provided a piston and barrel disc assembly 9 as shown in Figs. 8, 9 and 10. The disc assembly 9 is fitted to the back plate 1 b so that the cam 7 projects into a centre apperture 10 of the disc. The disc assembly 9 is drilled to provide diametrically opposed barrels or cylinders 11 a, 12a within which a pair of pistons 11, 1 2 are fitted. The pistons 11, 12 are adapted to receive balls 1 3 and 14 which serve as cam followers. The pistons are biased by means of springs 1 5 and 1 6 contained within the cylinders 11 a and 1 2a whereby the balls 13, 14 are biased against the cam 7.As shown most clearly in Fig. 11, the end of the piston 11 remote from the ball 1 3 is formed with a groove 11 b on the crown thereof to accomodate the spring 1 5 and the piston 1 2 is fabricated in a similar manner. The pistons are also provided with a circumferential groove 16 to accommodate a piston ring which serves for sealing purposes. The ends of the barrels 11 a and 1 2a within which the pistons 11 and 1 2 are constrained to reciprocate are sealed by means of plugs 1 7 and 1 8 which incorporate inlet valves 1 7 a and 18a respectively.The inlet valves serve to ensure that pressurised air in the cylinders cannot escape through air inlet passages 1 9. The inlet passages 1 9 communicate with an air filter chamber 20 filled with sponge moistened with oil which receives air at atmospheric pressure through vent holes 21. In an alternative embodiment (not shown) the inlet valves 1 7a, 1 8a may be adapted to include a pressure sensing diaphragm responsive to tyre pressure for controlling operation of the inlet valve whereby tyre pressure is limited to a predetermined value.

Pressure is released from the cylinders 11 a and 1 2a via adjustable ball valves one for each cylinder, only one of which 22 is shown in Figs. 9 and 11. Compressed air from a passageway 22a is fed via an inlet pipe 23a to an air pressure limiting valve 23 which operates to limit the pressure of the compressed air which is fed via a flexible tube 24 to the tyres. The tube 24 may be terminated by a connector valve which is normally closed but which opens when screwed to a standard inlet valve of the tyre. Such connector valves are well known.

The inlet valves 1 7 a and 1 8 a and the adjustable ball valves 22 and the air pressure limiting valve 23 are all conventional spring biased ball valves. The construction of these valves is well known as can be seen from the drawings and they will not be described herein in any great detail. The adjustable ball valves are adjustable by means of a screw 22 b which affords a preset adjustment and the pressure limiting valves are adjustable by means of a screw adjuster 25.

The pressure limiting valve 23 is mounted externally of the compartment 4 as can be seen in Fig. 1 and includes an inlet valve 26 by means of which air may be fed to the tyre from an external compressor. The air pressure limiting valves 23 are arranged so that the adjuster 25 projects externally of the outer cover 1 a whereby pressure adjustment is facilitated when the tyre pressure regulator is fitted to the wheel. In an alternative arrangement however, pressure adjustment may be preset by means of a grub screw adjuster provided in place of the adjuster 25.

It will be appreciated that in operation of the tyre pressure regulator, the counterweight 8 tends to hang downwardly from the spindle 5, the mass of the counterweight resisting forces tending to rotate it. Thus it will be appreciated that as the pistons 11 and 1 2 are rotated with the wheel, pump operation will be effected as the balls bear against the cam and as the pistons rotate with respect to the cam. When the pressure in the barrels 11 a and 1 2 a exceeds the pressure determined by the adjustable ball valves 22, air is passed to the inlet pipe 23awhich communicates with the tyre. If the pressure fed to the tyre exceeds the pressure set by the adjuster 25, then air escapes via the air pressure limiting valve 23 to atmosphere. It will be appreciated that the adjustable ball valves normally be preset to an air pressure above the highest tyre pressure required.

It will also be appreciated that a tyre pressure regulator according to the present invention will maintain optimum pressure at all times thereby saving considerable amounts of fuel and giving a high mileage. It will be appreciated that the correct tyre pressure aids comfortable and safe driving and helps to eliminate bumping which may be caused at higher tyre pressure promotes increased tyre life. By using a tyre pressure regulator according to the present invention cumbersome and regularly repeated manual checking and repressrising of tyres is substantially eliminated.

Claims

1 A tyre pressure regulator comprising a housing adapted to be secured to the hub of a wheel carrying a pneumatic tyre so as to rotate therewith, a counterweight journaled within the housing so as to permit rotary movement between the housing and the counterweight about the axis of the wheel, pneumatic pump means secured within the housing, the counterweight being adapted to cooperate with the pump means in response to rotary movement between the counterweight and the pump means produced consequent upon rotation of the wheel so as to effect pump action, and pressure regulator valve means operative to ensure that pressurised air from the said pump means is supplied to the pneumatic tyre at predetermined pressure.

2. A tyre pressure regulator as claimed in claim 1 wherein the adaption of the counterweight comprises a cam which is secured to the counterweight to form a unit, the pump means including cam follower means, the cam follower means being operatively associated with the cam for driving the said pump means in response to rotary movement between the cam follower means and the cam, produced consequent upon rotation of the wheel.

3. A tyre pressure regulator as claimed in claim 1 or claim 2 wherein the housing is adapted to clip onto the wheel so as to serve as a hub cap.

4. A tyre pressure regulator as claimed in any preceding claim wherein the housing comprises an outer body and a back plate, the back plate being secured to the outer body so as to define therebetween a compartment in which the pump means and the counterweight are received.

5. A tyre pressure regulator as claimed in claim 4, wherein the counterweight and cam unit are journalled in a bearing which is fitted in the outer body and the pump means is secured to the back plate.

6. A tyre pressure regulator as claimed in any of claims 2 to 5 wherein the pump means comprises at least one piston which is arranged to be driven by the cam via the cam follower means.

7. A tyre pressure regulator as claimed in claim 6 comprising two diametrically opposed pistons, one end of each piston being adapted to receive a ball which serves as a cam follower, the other end of each piston being formed with a groove to receive a piston ring which provides a seal against the walls of a cylinder or barrel in which it is received.

8. A tyre pressure regulator as claimed in claim 7 wherein the pump means comprises an annular disc formed to provide two diametrically opposed cylinders or barrels in which the pistons are received, the cam being arranged to project into the centre aperture of the annular disc and to co-operate with the balls at the ends of the pistons, the balls being biased against the cam by biasing means contained within the cylinders or barrels which act on the ends of the pistons remote from the balls.

9. A tyre pressure regulator as claimed in claim 8 wherein the biasing means comprises springs which are fitted in recesses in the crowns of the pistons.

10. A tyre pressure regulator as claimed in claim 8 or claim 9 comprising inlet means provided at the end of each cylinder remote from the pistons, via which air is admitted to the cylinder, but via which air above atmospheric pressure cannot escape.

11. A tyre pressure regulator as claimed in claim 10 wherein the inlet valve means comprise ball valves fed from atmosphere via an inlet filter contained in a passageway within the annular disc.

12. A tyre pressure regulator as claimed in any of claims 8 to 11, comprising an outlet passageway provided at the end of each cylinder or barrel remote from the pistons which communicates with the tyre via the said pressure regulator valve means.

1 3. A tyre pressure regulator as claimed in claim 12 wherein the pressure regulator valve means comprises an adjustable valve disposed within each outlet passageway and an adjustable pressure limiting valve which is positioned outside the compartment, the adjustable valves being set to pass to the tyre air from the pump means only if it exceeds a preset tyre pressure, and the pressure limiting valve being set to determine the maximum pressure of air in the tyre.

14. A tyre pressure regulator as claimed in claim 1 3 wherein the pressure limiting valve is provided with a pressure regulating control which projects through the outer body so as to facilitate adjustment after the tyre pressure regulator has been fitted to a wheel.

15. A tyre pressure regulator as claimed in claim 14 wherein the pressure regulating control is fitted with an inlet valve which communicates with the outlet passageways and by means of which the tyre may be inflated from an external compressor.

1 6. A tyre pressure regulator substantially as hereinbefore described with reference to the accompanying drawings.