GB2360748A

GB2360748A - Motion-powered vehicle tyre inflation pump

Info

Publication number: GB2360748A
Application number: GB0007803A
Authority: GB
Inventors: Roger Nelson White
Original assignee: Individual
Current assignee: Individual
Priority date: 2000-03-30
Filing date: 2000-03-30
Publication date: 2001-10-03
Also published as: GB0007803D0

Abstract

The pump replaces a normal tyre valve and comprises a bladder 5 located in the interior of a tyre which flexes in response to the interior pressure fluctuations created when the tyre encounters an obstacle on the road. This flexing motion operates a pressure intensifier for compressing air when a higher pressure is required. The intensifier comprises a diaphragm 6, of the bladder 5 operating a diaphragm 9 of a higher pressure chamber 10 fed via a one way valve 11, the diaphragms being separated by a lower pressure chamber 7. When the tyre is up to pressure, the bladder diaphragm 6 presses the diaphragm 9 against a wall of the chamber 10 to prevent operation. A valve 4 delivers compressed air from the intensifier to the interior of the tyre.

Description

1 2360748 MOTION-POWERED VEHICLE TYRE INFLATION PUMP This invention

relates to a motion-powered vehicle tyre inflation pump, which automatically maintains the correct tyre pressure.

Pneumatic vehicle tyres operate most effectively when inflated to the correct pressure as stipulated by the tyre manufacturer. In the course of normal operation the compressed air within the interior of a tyre may leak out due to the perforation of the tyre by a foreign object or by the degradation of the seal between the tyre and the wheel rim on to which the tyre is fitted through corrosion of the wheel rim. In either case the resultant reduction in pressure reduces the effectiveness of the tyre.

According to the present invention there is provided a motion-powered vehicle tyre inflation pump comprising a sealed flexible bladder which is responsive to the interior pressure of the tyre, an intensifier pump for compressing air when a higher pressure is required and a valve which delivers compressed air from the intensifier pump to the interior of the tyre.

A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawing in which:

Figure 1 shows a schematic sectioned general arrangement of the motionpowered vehicle tyre inflation pump mounted on a vehicle wheel with tyre; Figure 2 shows an enlarged general arrangement of the motion-powered vehicle tyre inflation pump; Figure 3 illustrates the inability of the intensifier pump to operate at the correct tyre pressure; and Figure 4 illustrates the operation of the intensifier pump at a reduced tyre pressure.

2 When a pneumatic tyre encounters an obstacle on the road it deforms. In many instances this will cause the interior volume of the tyre to decrease and the pressure to increase. The present invention uses these pressure pulses to compress air and emit it in to the interior of the tyre when a higher pressure is required.

Referring to Figures 1 and 2 all the components of the motion-driven vehicle tyre inflation pump are contained within or supported by the pump body 1 which fits in replacement of an existing tyre valve. The tyre can be inflated or deflated in the normal manner by unscrewing the airtight cap 2 and emitting/expelling air through the standard size inlet pipe 3 and valve 4 (detail not shown).

A sealed flexible bladder 5 is located within the interior of the tyre and contains a compressed gas the pressure of which depends on the manufacture's recommended tyre pressure. When the tyre pressure is correct, for example 2 bar, the diaphragm 6 that forms part of the bladder wall expands in to and is constrained by the lowpressure cylinder 7 as illustrated in Figure 3. Hence, at the correct tyre pressure, the pumps motion is completely restricted so it cannot over-pressurise the tyre.

In this example, when the tyre pressure falls below 2 bar the bladder expands and its internal gas pressure drops causing the diaphragm 6 to come away from the wall of the low-pressure cylinder 7 as illustrated in Figure 4. The pump can now operate. Pressure fluctuations resulting from an obstacle on the road will cause the bladder to compress increasing its internal pressure that in turn will expand the diaphragm 6 in to the lowpressure cylinder 7. This motion is transmitted via a rod 8 to a second much smaller diameter diaphragm 9 located in the high-pressure cylinder 10 of the intensifier pump. The action of diaphragm 9 causes valve 11 (detail not shown) to close enabling the air in cylinder 10 to be compressed to a pressure greater than the required tyre pressure so enabling it to enter the interior of the tyre via valves 12 and 4 and pipe 13.

When the tyre has relaxed back to its original volume having overcome the obstacle, diaphragms 6 and 9 will retract causing ambient air to be drawn in to the highpressure cylinder 10 via the inlet pipe and valve 11 ready for the next compression cycle. The air between the two diaphragms is vented to the atmosphere by pipe 14.

3

Claims

1 A motion-powered vehicle tyre inflation pump to fit in replacement of an existing tyre valve comprising of a bladder, which responds to the interior pressure of the tyre thus operating a pressure intensifier pump for compressing air when a higher pressure is required. 2 A motionpowered vehicle tyre inflation pump as claimed in Claim 1 wherein the compliance of the diaphragm which forms part of the bladder wall controls the displacement of the pressure intensifier pump. 3 A motion-powered vehicle tyre inflation pump as claimed in Claim 1 or Claim 2 wherein the diaphragm which forms part of the bladder wall is constrained by the pump body when the tyre is at the correct pressure thus limiting the displacement of the pressure intensifier pump.