WO2006095144A1

WO2006095144A1 - Electronic vehicle tyre inflator

Info

Publication number: WO2006095144A1
Application number: PCT/GB2006/000764
Authority: WO
Inventors: Mark Christopher Mccaughey
Original assignee: Pneumatic Components Limited
Priority date: 2005-03-08
Filing date: 2006-03-03
Publication date: 2006-09-14
Also published as: GB0504735D0

Abstract

A digital electronic vehicle tyre inflator (1) comprises a housing (2) having a visual display screen (7), a compressed air supply port (42), a delivery port (45) to a tyre, and a gauge port (46); user-operable valve means (19, 16) within the housing (2) to control the flow of air during tyre inflation and deflation, and a microprocessor (34) coupled to an electronic pressure transducer (26), to a battery pack or external power supply and to a numerical visual display, wherein, in use, the microprocessor (34) initiates frequent monitoring (e.g. ten times per second) by the transducer (26) of the rise or fall of pressure between the last recorded gauge pressure and the next inflation/deflation value, from which data a rate of change of pressure is calculated, and as a result of such calculation if the rate of change is within a predetermined range, displays gauge pressure, or if the rate of change falls outside the predetermined range, suppresses display of the gauge pressure to a blank screen, or zero value, or non-numerical display.

Description

Title of the Invention

Electronic vehicle tyre inflator Field of the Invention

This invention relates to a hand held or hand operated digital electronic vehicle tyre inflator.

Background of the Invention

Electronic tyre inflators are known, which, to replicate some features of mechanical inflators which have been provided for decades at filling stations, have a facility for visual display of a pressure. However, visual displays on electronic tyre inflators are frequently prone to error, or operator confusion, which has led, in some markets, for a requirement for no visual display during inflation or deflation. Inaccurate displays occur particularly, when deflating, or with varying lengths of supply hose, when the air pressure in the supply hose has not settled to that in a tyre. To achieve compliance with the markets requiring no visual display, manufacturers have utilised valves which during inflation or deflation render the gauge port open to atmosphere, but such modified values typically contain a part count higher than conventional valves, and hence increase costs. In most cases the valves, during inflation, isolate the supply pressure from the gauge port. However there is a state so-called "dither" where momentarily the supply pressure can be diverted between the tyre and atmosphere allowing uncontrolled rise and fall in pressure values.

During deflation, the expelled tyre pressure appears at the gauge as a partial pressured reduced from the actual decaying tyre pressure. The fall in pressure exceeding allowable limits forces a blank screen or zero value or non-numerical display.

The return to indicated pressure is given by a determined pressure rise, this being variable according to pressure head in the tyre. Object of the Invention

A basic object of the present invention is the provision of an improved digital electronic vehicle tyre inflator. Summary of the Invention

According to the present invention, there is provided a digital electronic vehicle tyre inflator comprising

(i) a housing having a visual display screen, a compressed air supply port, a delivery port to a tyre, and a gauge port (ii) user-operable valve means within the housing to control the flow of air during tyre inflation and deflation, and (iii) a microprocessor coupled to an electronic pressure transducer, to a battery pack or external power supply, and to a numerical visual display, wherein, in use, the microprocessor initiates frequent monitoring by the transducer of the rise or fall of pressure between the last recorded gauge pressure and the next inflation/deflation value, from which data a rate of change of pressure is calculated, and as a result of such calculation if the rate of change is within a predetermined range, displays gauge pressure, or if the rate of change falls outside the predetermined range, suppresses display of the gauge pressure to a blank screen, or zero value, or non-numerical display. Advantages of the Invention

By ensuring that display is effected when the rate of change is relatively slow, an accurate visual display of gauge pressure can be attained, while a rapid change - indicating for instance a pressure spike - results in a suppressed display, so that erroneous numerals having no relationship to the tyre pressure but resulting from a spike, are not displayed to the user.

Furthermore, the inflator in accordance with the invention may incorporate any of several widely available simple low cost valve systems, with fewer components, without needing to utilise a valve with atmospheric porting gauge when inflating and deflating.

The invention also obviates problems resulting from substantial hose lengths, and the consequent restriction on hose lengths by permitting the use of varying lengths of hose to tyre i.e. from 0.5 metre upwards to a possible 100 metres, as the equalization of pressure air in the hose to pressure of air in the tyre is measured only when the air has balanced to a pressure within an accepted standard of accuracy before pressure display is effected. The connected tyre hose is in effect scanned until the recorded pressure values are of a close value to be equalized. Clearly, the settling time is variable according to the dynamic equalization effects of hose length volume v tyre valve restriction v Input pressure v actual tyre pressure. This may be calculated with screen held blank or with a zero display or with a non-numerical display, with the result that the measurement of hose to tyre pressure equalization/settling time allowing the adoption of longer lengths of tyre inflator outlet hose, of up to 100 metres. Preferred or Optional Features of the Invention The transducer is a piezo resistive pressure sensor. The visual display is an L.C.D.

The visual display is an L.E.D.

The transducer is mounted directly into a hose outlet according to the maximum allowable over pressure limitation of the pressure sensor thereby offering an alternative valve design.

Brief Description of the Drawings

Figure 1 is a sectional side elevation of an inflator in accordance with the invention with the components shown in a "gauge" position;

Figure 2 is a section on the line H-Il of Figure 1 ; Figure 3 is a section on the line Ill-Ill of Figure 1 ;

Figure 4 is a view of a portion of Figure 1 with the components in a "deflate" position;

Figure 5 corresponds to Figure 1 but shows the components in the "inflate" position; Figure 6 is a section on the line Vl-Vl of Figure 5; and

Figure 7 is a section on the line VII-VII of Figure 5.

In the drawings, an inflator 1 has a handgrip and housing 2 for internal components secured to the body 1 by screws 3 with a cover 4. A bezel 5 secured by screws 6, forms part of visual, air pressure display, including a screen 7, whilst a boot 8 encases the screen 7 and bezel 5. A lever 9 is mounted on a rocker arm 10 via a pin 11 , with the arm 10 mounted at its other end on a pin 41 the ends of which are closed off by dome caps 12.

Into one end of the body 1 is secured an inlet connector 13 providing a compressed air supply port 42, with an O-ring seal 14 between the connector 13 and body 1. An inlet, compression spring 15 extends between an inner end of the inlet connector 13 and an inlet valve 16 to bias the latter to its closed, seated position, the valve 16 having a seal 17 to engage a valve seat 43 provided on the body 1 and a contact end 48.

Remote from the inlet connector 13, the inflator 1 is provided with an outlet hose tail piece 18 (no hose being shown) mounted on an outlet valve 19 with an O- ring seal 20 between the tail piece 18 and outer periphery 44 of the valve 19 which also has a contact end 49. The tail piece 18 and valve 19 provide a compressed air delivery port 45 to a tyre (not shown). A pin 21 of the lever 9 engages a groove of the outlet valve 19, whilst an outlet spring 22 surrounds a portion of the valve 19, an inner end of the latter carrying an O-ring 23.

A housing elbow 24 is connected to a gauge port 46, with an O-ring seal 25 between a spigot 47 of the elbow 24 and the gauge port 46.

A pressure transducer, in the form of a ceramic pressure sensor cell 26 is carried by the elbow 24, with an O-ring seal 27 between the cell 26 and the elbow 24.

The sensor cell 26 is connected by a lead 56 to a PCB with a microprocessor 34. The latter is programmed by conventional means, using a conventional programming language, (i) to record a gauge pressure, (ii) to effect frequent data capture e.g. ten times per second of the rise, or fall, of pressure sensed by the cell 26, between the last recorded gauge pressure and the next inflation/deflation pressure, from which data a rate of change of pressure may be calculated, and (iii) if the rate of change is within a predetermined range, to initiate a digital pressure display at the screen 7, but if outside the predetermined range, to suppress display of a misleading pressure.

A deflate housing 28 sealed by another O-ring 29, houses a deflate valve 30 biased to its closed, sealed position by a deflate compression spring 31 , with the deflate valve 30 provided with an O-ring 32. The deflate valve 30 has a head 54 beneath a resilient cover 55. A sensor cap 39 is secured in place by two screws 40 engaging locking nuts 33.

As best seen in Figure 5, screws 35 serve for the mounting of a battery cradle 36, with a removable battery insulator indicated at 37, and a battery coin cell at 38.

In use, in the "rest" or gauge position illustrated in Figures 1 to 3, the inlet, outlet and deflate valves 16, 19 and 30 are also seated in their closed positions, under the bias of their respective compression springs and the gauge port 46 is in communication with the delivery port 45. Thus, there is no flow into the inflator 1 , whilever the inlet valve 16 remains seated.

When a user wishes to inflate a tyre, the user squeezes the rocker arm 11 to rotate the rocker arm 11 clockwise to the position shown in Figure 5.

In this position, the rocker arm 11 , via the pin 21 has displaced the outlet valve 19 to the left, resulting firstly in its seal 23 passing beyond the gauge port 46 thereby connecting the gauge port 46 to atmosphere via annular areas 50 and 51 , and resulting secondly in the eventual abutment of contact 49 and 48, in turn resulting in unseating of the inlet valve 16, so that compress air is suppliable to the tyre via annular area 52 and delivery port 46, with isolation of the gauge port 46 now at atmospheric condition resulting in no elevated pressure reading at the display screen 7. To obtain a reading the user releases rocker arm 11 resulting in seating of the inlet valve 16, the air supply being closed off, and air in the supply port 42 and the delivery hose (not shown) to the tyre being connected to the gauge port 46.

If the user, from a reading on the screen 7, has over-inflated a tyre, then the user presses the head 54 of the deflate valve 30, to achieve the position indicated in

Figure 4, where air in the hose and delivery port 45 is able to escape to atmosphere via unseated deflate valve 30 and ports 53 in the housing 28. Release of the deflate valve 30 results in its spring 31 seating the valve so that pressure in the hose and in the delivery port 45 is again available at the sensor cell 26, enabling the microprocessor 34 to generate a digital pressure readout at screen 7.

This process is repeated until the desired tyre pressure is attained.

Claims

1. A digital electronic vehicle tyre inflator (1) comprising:

(i) a housing (2) having a visual display screen (7), a compressed air supply port (42), a delivery port (45) to a tyre, and a gauge port (46),

(ii) user-operable valve means (19, 16) within the housing (2) to control the flow of air during tyre inflation and deflation, and

(iii) a microprocessor (34) coupled to an electronic pressure transducer (26), to a battery pack or external power supply and to a numerical visual display (7), wherein, in use, the microprocessor (34) initiates frequent monitoring by the transducer (26) of the rise or fall of pressure between the last recorded gauge pressure and the next inflation/deflation value, from which data a rate of change of pressure is calculated, and as a result of such calculation if the rate of change is within a predetermined range, displays gauge pressure, or if the rate of change falls outside the predetermined range, suppresses display of the gauge pressure to a blank screen, or zero value, or non-numerical display.

2. An inflator as claimed in Claim 1 , wherein the transducer (26) is a piezo resistive pressure sensor.

3. An inflator as claimed in Claim 1 or Claim 2, wherein the visual display (7) is an LCD.

4. An inflator as claimed in Claim 1 or Claim 2, wherein the visual display (7) is an LED.

5. An inflator as claimed in any preceding claim, wherein the transducer (26) is mounted directly into a hose outlet according to the maximum allowable over pressure limitation of the pressure sensor thereby offering an alternative valve design.