CA2280521A1 - Tyre pressure warning system - Google Patents

Tyre pressure warning system Download PDF

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Publication number
CA2280521A1
CA2280521A1 CA002280521A CA2280521A CA2280521A1 CA 2280521 A1 CA2280521 A1 CA 2280521A1 CA 002280521 A CA002280521 A CA 002280521A CA 2280521 A CA2280521 A CA 2280521A CA 2280521 A1 CA2280521 A1 CA 2280521A1
Authority
CA
Canada
Prior art keywords
sensor
tyre
pressure
transmitter
unit
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
CA002280521A
Other languages
French (fr)
Inventor
David Caradoc Owens
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
XPERTECH Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by XPERTECH Ltd filed Critical XPERTECH Ltd
Publication of CA2280521A1 publication Critical patent/CA2280521A1/en
Abandoned legal-status Critical Current

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Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60CVEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C23/00Devices for measuring, signalling, controlling, or distributing tyre pressure or temperature, specially adapted for mounting on vehicles; Arrangement of tyre inflating devices on vehicles, e.g. of pumps or of tanks; Tyre cooling arrangements
    • B60C23/02Signalling devices actuated by tyre pressure
    • B60C23/04Signalling devices actuated by tyre pressure mounted on the wheel or tyre
    • B60C23/0408Signalling devices actuated by tyre pressure mounted on the wheel or tyre transmitting the signals by non-mechanical means from the wheel or tyre to a vehicle body mounted receiver

Abstract

A tyre pressure monitoring system for a vehicle that has a plurality of sensor/transmitter units (2, 4) one for each tyre of the vehicle. Each sensor/transmitter unit has a pressure transducer (2) and a processor (14). The processor (14) compares a current pressure signal from the transducer with a pressure signal stored in its memory which corresponds to the pressure first encountered on installation of the transducer. The processor (14) includes means to transmit a fault signal when the current pressure signal differs from the stored pressure signal by more than a predetermined amount. A control unit (6) receives fault signals from the transducers and includes means (24) for indicating that a fault has occurred.

Description

TYRE PRESSURE WARNING SYSTEM
This invention relates to a tyre pressure warning system of the type which can be used on vehicles to advise the driver if the pressure in any of the tyres on the s wheels of the vehicle changes from a predetermined value by more than a given amount. Typically, it will be used to warn the driver of deflation of the tyre.
The present invention is an improvement on a system known as TireMate which has been sold in the United io States. This consists of a pressure sensor/transmitter, which replaces the dust cap on the outer end of a tyre valve. The sensor/transmitter is a mechanical pressure sensor. It is preset with a reference pressure, the ideal pressure for the tyre on which it is to be mounted, and a is triggering pressure. If the pressure in the tyre falls to the triggering pressure the sensor/transmitter transmits only its identity to a control unit which then indicates to the driver that a fault has occurred on that. Thus, when the pressure in the tyre becomes too low the driver 2o will be warned of this and will have the option of doing something about it. The sensor/transmitter unit transmits continuously until the battery powering it is discharged.
One problem with this system is that sensor/transmitter units have to be preset with desired z5 and triggering pressures. This is normally done at manufacture and means that units cannot easily be switched to other vehicles with tyres that run at different pressures.
The present applicants have appreciated that the so driver of the vehicle does not need to be constantly reminded of the pressure in the tyre and, thus, does not WO 98/34799 PCTlGB98/00358 need repeated transmission of pressure data from the sensor to the data processing and display unit. All that the driver requires is a warning of some kind when the pressure in the tyre differs from the desired pressure by s more than a predetermined amount. It is not necessary to transmit the exact pressure data. Thus, a preferred embodiment of the invention provides a system in which the sensor/transmitter only transmits an over or under pressure signal to the data processing and display unit io when the pressure in the tyre differs from the desired pressure by more than a predetermined amount.
Another problem with the prior art system arises from the fact that the temperature of tyres on motor vehicles can vary considerably. The temperature of tyres on a is vehicle which has been driven for some time will be significantly higher than the temperature at rest and this will cause a significant increase in pressure. Also, in some environments, e.g., the desert, temperatures between night time and day time vary by a considerable amount 2o thereby leading to variations in pressure entirely dependent on temperature.
In accordance with a further embodiment of the present invention, a sensor/transmitter device is provided to replace a standard dust cap. A thermistor is provided 2s and is exposed to the gas filling the tyre and thus is sensitive to temperature changes in the gas. A software driven microprocessor receives a signal from the thermistor and is thus able to take account of temperature changes in determining whether or not there has been any 3o increase or decrease in the real pressure in the tyre.
The invention is defined in the appended claims to which reference should now be made.
Preferred embodiments of the invention will now be s described in detail by way of example with reference to the accompanying drawings in which:
Figure 1 shows a schematic diagram of a system embodying the invention;
Figure 2 shows a schematic diagram of a sensor embodying the invention; and Figure 3 shows a schematic diagram of a further embodiment of the invention for use on vehicles with io detachable trailers.
In Figure 1, there are shown four sensor units 2 each coupled to a respective transmitter 4. These units are included in a unit which screws onto a tyre valve and replaces its dust cap. On a four-wheel vehicle the system is would be as shown in Figure 1 with four sensor/transmitter units, one attached to the dust cap on each wheel. It can however be used on two wheel vehicles or vehicles with more than four tyres or wheels.
The pressure transducers used in the zo sensor/transmitter units are electronic sensors under microprocessor control. They are controlled to transmit to a control unit an identification code when they are installed on a tyre. They are also controlled to measure and record the pressure they first encounter when they are 2s installed on a tyre. This is stored in memory and is used for comparison with the tyre pressure during use to determine wether the tyre pressure has changed by more than a predetermined amount. Preferably this change is monitored as a percentage of the first encountered ao pressure, e.g. 15%. The transducers used preferably have a range from 0.5 to 10 bar and this enables the same sensor/transmitter units to be used on a wide range of vehicles.
A data processing unit 6 is provided in the cab of the vehicle in a position where it can be viewed by the s driver. This data processing unit is coupled to a receiver 8 which receives signals transmitted by the transmitters 4. It is also coupled to a display 10 which is used to display tyre deflation/inflation warning information to the driver. The display 10 is preferably an io alphanumeric display of, for example, the liquid crystal type. Thus it can provide instructions and information to the user.
The sensors are coupled to the microprocessor which monitors the output signal from its respective sensor and, i5 if the signal alters in such a way as to indicate that the pressure in the respective tyre has changed from the first encountered pressure by more than the predetermined amount, the processor controls the transmitter to transmit a warning signal to the data processing unit 6 which 2o receives it by means of receiver 8. This warning signal comprises an identification signal identifying the sensor.
In this particular embodiment the identification signal is a 16-bit coded signal which enables over 65,000 different sensor identification codes to be used. This makes the 25 chance of a signal from a sensor with a corresponding ID
on another vehicle being sent to the data processing unit 6 very remote. Previous systems such as the TireMate system included the possibility of only 14 individual settings for sensor identification codes.
3o The sensor/transmitter units are arranged to transmit every 24 hours an OK signal to the data processing unit 6 if no fault condition is detected within a 24 hour period.
The purpose of this signal is to ensure that the data processing unit has information indicating that all sensor/transmitter units on a vehicle are working. Thus, if a fault develops on a unit or its battery runs out of s power, no OK signal will be sent to the data processing unit 6 and this can then indicate to the driver via the display 10 that there is a problem with the sensor/transmitter unit on a particular wheel of the vehicle. Furthermore, the sensor/transmitter is preferably io arranged to detect faults with the sensor and to transmit to the control unit a sensor fault signal to the driver indicating that a problem has occurred with a particular sensor.
The sensor units are designed to determine the i5 pressure of the tyres on which they are installed, store this pressure in memory and, subsequently, trigger a fault condition transmission when the pressure change within the tyre is, for example, plus or minus 15% from the pressure originally measured and stored. Thus, there is no 2o requirement for triggering of fault condition signals at predetermined pressures.
when a fault condition is detected the sensor/transmitter in this embodiment sends the fault signal repeatedly over a period of 30 seconds. The z5 transmission is then terminated to save the battery life of the sensor. Thereafter, the alarm transmission is repeated every 15 minutes for a 30 second period. To rectify a fault the sensor/transmitter unit is removed from the tyre by unscrewing the dust cap. Exposure of the 3o transducer to atmospheric pressure causes the sensor to reset and causes the fault transmission to cease. These timings can of course be varied as desired.
Another embodiment of a sensor/transmitter unit is shown in Figure 2. In this, it can be seen that the sensor comprises a sensor unit 2 (preferably an electronic sensor) which is responsive to the tyre pressure and a s thermistor 12 (temperature dependent resistor) which changes resistance as the temperature in the tyre changes.
The processor 14 monitors the signal from the sensor 2 and from the thermistor 12. From this, it is able to determine what temperature increase or decrease in the io tyre has occurred and thus is able to compensate the signal from the sensor for this temperature increase/decrease. This avoids the sending of a spurious fault condition signal when pressure increases or decreases purely because of a large change in temperature.
i5 It ensures that fault transmissions only occur when there is some other cause for an increase/decrease in pressure.
The data processing and display unit is used to record the identities of sensor/transmitter units installed on a vehicle. This information is stored in 2o memory. The control unit prompts a person installing the sensor/transmitter units to install the units on each tyre in turn. Prompting is done via the display 10 where an indication of the tyre on which the next unit to be installed is made. When each unit is installed, the zs initial exposure to the tyre pressure causes it to transmit its identification code to the control unit. Thus the control unit is able to record the identification code for the unit installed on each tyre.
The data processing unit validates any transmission so received by ensuring that it is repeated several times in the same format. This it does during the transmission period of 30 seconds from a fault condition being detected and transmission of that commencing. This is done to exclude spurious transmissions and to ensure that the identity code received relates to a sensor which has previously been recorded as being installed on the s particular vehicle.
Details of any fault transmission which are received by the data processing and display unit are stored in memory together with the tyre position concerned and the time at which that observation was made. Thus, if the io fault occurs while the vehicle is not being driven it is stored and will be provided to the driver via the display and an audible alarm 11 when the vehicle is next switched on. Similarly, the failure of any sensor to transmit an OK signal will be stored in memory together with the tyre is position concerned so that the driver will be alerted of the failure of that sensor/transmitter to operate correctly.
In many commercial vehicles, separate tractor and trailer units are used, particularly in the road haulage 2o industry. Trailers may be disconnected from tractors for a considerable period of time and may in fact be reconnected to different tractors. If a tyre deflation should take place whilst a trailer is disconnected, the tractor unit with the standard data processing and display 2s unit will not be in the proximity and, thus, details of the failure will not be stored. To overcome this, a separate data transceiver unit is provided on a trailer.
This is illustrated in Figure 3. In this, a data transceiver unit 16 is provided mounted on a trailer and 3o is coupled to a receiver 18. This receives signals from sensors/transmitters mounted on the wheels of the trailer.
It includes a memory which stores any fault condition _ g signals and the OK signals received while a trailer is not connected to a tractor. A separate power supply is included in the data transceiver unit 16 and this is preferably a rechargeable battery which is recharged when s the transceiver is connected to the power supply of a tractor.
On the tractor is provided a normal data processing unit 6 and display 10 of the type shown in Figure 1. This is coupled to a receiver 8 which receives signals from io sensor/transmitters mounted on the wheels of the tractor unit.
A connector 20 is used to couple the data processing unit to the data transceiver when the tractor unit is coupled to the trailer for power supply. On initial is coupling, all data stored by the data transceiver is down loaded to the tractor unit. This comprises the identities and locations of the sensors mounted on the trailer, whether or not any fault condition has occurred on any of these, and details of whether the OK signals required 2o every 24 hours have been received.
The connection 20 between the data transceiver 16 and the data processing unit 6 need not be a hard-wired connection. The data transceiver could be provided with a transmitter 22 which, when a tractor is linked to the 2s trailer, could be organised to transmit all the relevant information to a receiver 24 on the data processing unit 6. Thereafter, signals from the trailer sensor transmitters could be received either by the data transceiver 16 or by the data processing unit 6.
so Using this arrangement enables tractors and trailers to be interchanged without having to reprogramme the tyre pressure warning system.

Claims (7)

1. A tyre pressure monitor system for a vehicle comprising a plurality of sensor/transmitter units for mounting on each tyre of the vehicle and a receiver/control unit;
each sensor/transmitter unit comprising pressure sensor means, processing means for comparing a current pressure signal from the sensor means with a pressure signal stored in a memory means and corresponding to the pressure first encountered on installation of the sensor/transmitter unit and means for transmitting a fault signal when the current pressure signal differs from the stored pressure signal by more than a predetermined amount;
the receiver/control unit comprising means for receiving signals from sensor/transmitter units and means for indicating that a fault condition has occurred in one of the tyre pressures in response to a received fault signal from a sensor/transmitter unit.
2. A tyre pressure monitoring system according to claim 1 in which the memory means in each sensor/transmitter unit stores an identification code associated with that unit and the sensor/transmitter unit is operable to transmit this identification code with a fault signal.
3. A tyre pressure monitoring system according to claim 2 in which each sensor/transmitter unit is controlled to transmit its identification code to the control unit when it is first installed on a tyre and stores its first encountered pressure signal.
4. A tyre pressure monitoring system according to claim 3 in which the control unit prompts a user of the system to install sensor/transmitter units on each tyre in turn.
5. A tyre pressure monitoring system according to claim 1, 2, 3, or 4 in which each sensor/transmitter includes means responsive to temperature of the tyre with which it is associated and means for compensating the pressure signal in dependence on detected temperature variations prior to comparison with the desired pressure signal.
6. A tyre pressure monitoring system for a vehicle comprising a plurality of sensor/transmitter units for mounting on each tyre of the vehicle and a receiver/control unit;
each sensor/transmitter unit comprising pressure sensor means for monitoring tyre pressure, temperature sensitive means responsive to temperature of the tyre with which it is associated, and means for transmitting data derived from the pressure sensor means and the temperature sensitive means;
the control unit comprising means for receiving data from the sensor/transmitter units and means for indicating that a fault condition has occurred in one of the tyre pressures.
7. A sensor/transmitter unit for monitoring tyre pressure comprising a pressure sensor means and a temperature sensitive means responsive to tyre temperature and means for transmitting data derived from the pressure sensor means and the temperature sensitive means.
CA002280521A 1997-02-05 1998-02-05 Tyre pressure warning system Abandoned CA2280521A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
GBGB9702295.8A GB9702295D0 (en) 1997-02-05 1997-02-05 Tyre pressure warning system
GB9702295.8 1997-02-05
PCT/GB1998/000358 WO1998034799A1 (en) 1997-02-05 1998-02-05 Tyre pressure warning system

Publications (1)

Publication Number Publication Date
CA2280521A1 true CA2280521A1 (en) 1998-08-13

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ID=10807092

Family Applications (1)

Application Number Title Priority Date Filing Date
CA002280521A Abandoned CA2280521A1 (en) 1997-02-05 1998-02-05 Tyre pressure warning system

Country Status (4)

Country Link
EP (1) EP0958154A1 (en)
CA (1) CA2280521A1 (en)
GB (1) GB9702295D0 (en)
WO (1) WO1998034799A1 (en)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4611537B2 (en) * 2000-06-09 2011-01-12 本田技研工業株式会社 In-vehicle tire pressure detector
EP2272688B1 (en) * 2000-07-26 2012-02-01 Bridgestone Americas Tire Operations, LLC Electronic tire management system
GB2386952B (en) * 2002-03-27 2005-09-07 Mitutoyo Corp Pressure gauge and pressure measuring system
JP3671942B2 (en) * 2002-07-24 2005-07-13 株式会社デンソー Tire pressure sensor ID registration method, tire pressure monitoring device, tire pressure sensor, and tire pressure monitoring program
US20050270148A1 (en) * 2004-06-07 2005-12-08 Calvin Modawell Trailer tire monitoring system and method
US7825782B2 (en) * 2007-03-20 2010-11-02 Ford Global Technologies, Llc Device and method for wireless vehicle communication

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4303591C2 (en) * 1993-02-08 1996-02-22 Alpha Beta Electronics Ag Valve cap with a device for generating a pressure indication signal for a vehicle tire equipped with a valve
EP0687225B1 (en) * 1993-03-11 1999-09-08 Schrader-Bridgeport International, Inc. Remote tire pressure monitoring system employing coded tire identification and radio frequency transmission, and enabling recalibration upon tire rotation or replacement
AU3392695A (en) * 1994-08-31 1996-03-22 Otter Controls Limited A tyre condition monitoring system
DE19522486C2 (en) * 1995-06-21 1999-04-22 Duerrwaechter E Dr Doduco Method for operating a device for monitoring and wireless signaling of a pressure change in pneumatic tires on vehicles

Also Published As

Publication number Publication date
GB9702295D0 (en) 1997-03-26
WO1998034799A1 (en) 1998-08-13
EP0958154A1 (en) 1999-11-24

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Legal Events

Date Code Title Description
FZDE Discontinued