EP1085990A1 - Capteur de pression pour pneu et systeme d'alarme correspondant - Google Patents

Capteur de pression pour pneu et systeme d'alarme correspondant

Info

Publication number
EP1085990A1
EP1085990A1 EP99906339A EP99906339A EP1085990A1 EP 1085990 A1 EP1085990 A1 EP 1085990A1 EP 99906339 A EP99906339 A EP 99906339A EP 99906339 A EP99906339 A EP 99906339A EP 1085990 A1 EP1085990 A1 EP 1085990A1
Authority
EP
European Patent Office
Prior art keywords
sensor
tyre
valve
pressure
collar
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.)
Withdrawn
Application number
EP99906339A
Other languages
German (de)
English (en)
Inventor
Christopher Nial Laing
Timothy Philip Smith
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.)
XPERTECH Ltd
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 EP1085990A1 publication Critical patent/EP1085990A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C23/00—Devices 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
    • B60C23/02—Signalling devices actuated by tyre pressure
    • B60C23/04—Signalling devices actuated by tyre pressure mounted on the wheel or tyre
    • B60C23/0491—Constructional details of means for attaching the control device
    • B60C23/0496—Valve stem attachments positioned outside of the tyre chamber
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C23/00—Devices 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
    • B60C23/02—Signalling devices actuated by tyre pressure
    • B60C23/04—Signalling devices actuated by tyre pressure mounted on the wheel or tyre
    • B60C23/0408—Signalling 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
    • B60C23/0422—Signalling 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 characterised by the type of signal transmission means
    • B60C23/0433—Radio signals

Definitions

  • This invention relates to a tyre pressure sensor and related alarm system
  • tyre pressure sensors exist One is desc ⁇ bed in published International Patent Application No WO-A 1-9728975 (University of B ⁇ tish Columbia)
  • the sensor indicates the degree of inflation of a tyre
  • the sensor includes an annular contact which rotates with the tyre
  • Another sensor is desc ⁇ bed in granted European Patent EP-B 1-610737 (Michehn & Cie) The sensor obtains values directly from tyres, compares these with those previously obtained and alerts a d ⁇ ver in the event of a deviation of tyre pressure from a pre-set value.
  • a processor performs compa ⁇ sons sequentially with signals received from each one of a plurality of sensors
  • a tyre pressure sensor which use is in fluid communication with a pneumatic tyre, the sensor comp ⁇ sing: a body, within which is located a diaphragm which displaces in accordance with a pressure va ⁇ ation within said tyre; a transducer is arranged to provide a signal 2 indicative of displacement of said diaphragm; and means for transmitting said signal characterised in that the sensor is adapted to be connected directly to the valve of a tyre.
  • a depressor is preferably supported by the body of the sensor.
  • the depressor is circularly symmetric and presents a protuberance which urges against the tyre valve as the sensor is connected thereto. Minimum air leaks from the tyre in this prefe ⁇ -ed embodiment.
  • connection is by way of a threaded connector.
  • Means may be provided to prevent overtightening of the sensor onto a valve stem.
  • a shearable collar is provided. Such a shearable collar also ensures that if there is an accidental impact against the sensor, the sensor body shears away at a predetermined position and does not deflate the tyre; but rather leaves only a threaded collar remaining attached to the tyre. If this occurs an alarm sounds and a driver is alerted to the fact that the sensor has been inadvertently dislodged.
  • a tyre pressure sensor which in use is connected to a valve of the tyre by way of a threaded collar, the sensor comprising a body and a depressor to open the valve, there being a shearable collar between the body and threaded collar, said shearable collar being dimensioned and arranged to shear at a predetermined shear stress so that the collar is detached from the sensor and depressor.
  • the sensor according to the second aspect of the invention preferably includes all the features of the first aspect; namely: a diaphragm, a transducer and a transmitter.
  • the means for transmitting the signal includes a radio frequency (if) transmitter.
  • the rf transmitter preferably includes a Surface Acoustic Wave (SAW) device.
  • SAW Surface Acoustic Wave
  • the transmitter may be an optical transmitter; a microwave transmitter or an acoustic (ultra sound) transmitter.
  • the diaphragm which preferably comprises piezoelectric (PZT) material, is advantageously a ⁇ anged in the sensor so that it is located within a generally cylindrical pressure chamber which in use is defined by the body of the sensor and the valve to which it is connected.
  • the pressure chamber is in fluid communication with the pneumatic tyre, when the sensor is screwed onto the tyre valve. This is because the depressor is presented to the valve; and as the sensor is screwed onto the valve's thread, the valve is depressed and opened. Minimum air leaks from the tyre because valve and sensor have relatively long threaded portions.
  • the pressure chamber of the sensor is advantageously isolated from the interior of the sensor and its other components by an 0-ring seal.
  • a transducer preferably contacts the diaphragm and is connected to an analogue- to-digital converter (ADC).
  • ADC provides a signal to a micro-processor also housed within the sensor.
  • the transducer preferably also incorporates a differential amplifier. 4 However, the differential amplifier may be a separate component. The transducer and differential amplifier are disposed on one half of a printed circuit board.
  • the analogue to digital converter forms part of the microprocessor.
  • the micro-processor provides a digital signal, indicative of the status of the tyre to a further amplifier. Control of all functions of the sensor are performed by the micro-processor. Amplified signals indicative of the status of the tyre are sent to the rf transmitter.
  • the rf transmitter is arranged to transmit at 433.92 or 418 MHz (or any approved frequency greater than 300 MHz) and has a range of about 100 m. Preferably at regular intervals a tyre status and tyre identification signal is transmitted. However, this feature can be disabled and the sensor arranged to transmit an alarm signal only when there is a pressure drop in the tyre.
  • a tyre pressure sensor alarm system comprising: a sensor having a transducer arranged to supply a signal indicative of tyre status to a micro-processor, said signal comprising two portions; the first portion being indicative of the sensor's origin (the identification portion); the second portion being indicative of the tyre's status (the status portion), and means for transmitting said signals to a receiver, characterised in that means is provided in the 5 receiver so that it can be reconfigured to receive a signal from a different sensor or group of sensors.
  • This aspect of the invention is considered particularly advantageous as it means the system is sufficiently versatile to enable the receiver to be removed and used with different trailers. Only the receiver unit needs to be reconfigured with each sensor of a new trailer.
  • the receiver unit overcomes the problem of having to remove a large number of sensors associated with one system and reconnect them to a new trailer. Instead a user simply has to remove the receiver unit and interrogate each sensor of a new trailer.
  • an alarm is arranged to trigger under certain conditions. Some of these conditions are described below.
  • a status portion of the signal is preferably derived from two sequential measurements obtained from the transducer and computed according to an algorithm stored in the micro-processor. If any two measurements differ, one from another by more than a predetermined amount, typically 15%, during a predetermined interval, an alert status is accorded to the status portion of the signal. The signal is then transmitted to a remote receiver. When the signal is received an alarm is triggered. If however, the two sequential measurements are substantially identical, or differ by an amount less than the aforementioned predetermined amount, then the status accorded to the signal is "ok". In this event, no alarm is triggered. However, if the receiver detects no signal from a sensor within a pre-set time period, then the system may be modified to trigger a different alarm. This alarm is called a fault alarm. This might occur if a sensor has been stolen, is damaged or if its battery supply is low.
  • a relay receiver optionally receives signals from a plurality of a first group of sensors and stores information about them, then may be used to store information as to status and "id" of a second group of sensors.
  • the receiver is preferably configured to be 6 used on trailers which are disconnected from haulage equipment for example tractor units of heavy goods (articulated) lorries.
  • Remote Excitation mode is used in some prior art systems. Such a function is not required by the present system as if a sensor unit fails, it is removed and discarded then replaced with a new one.
  • Figure 1 shows a block diagram of a tyre pressure alarm system
  • Figures 2a and 2b show plan and sectional views respectively of a sensor
  • Figures 3a and 3b shown plan and sectional views of a cap, which hermetically seals the sensor
  • Figure 4 is a general assembly showing key components and their location in the sensor
  • Figures 5a and 5b show front and rear views of a sensor board, identifying key components thereon;
  • Figures 6a and 6b show front and rear views of a circuit board for a transmitter portion of the sensor
  • Figure 7 shows a block diagram of a circuit board for use in the sensor
  • Figure 8a is an overall view of transducer on a circuit board; 7 Figures 8b, c and d show plan, underplan and side views (respectively) of the transducer;
  • Figure 9a is an electrical connection diagram showing mounting pads of the transducer
  • Figure 9b is an equivalent circuit diagram to the connection diagram of Figure 9a.
  • Figures 10a, b, c and d show printed circuit board layouts.
  • a sensor 100 is of a generally cylindrical form and includes a Schrader (Trade Mark) screw thread 102. Thread 102 permits the sensor to be connected to a stem of a valve (not shown) of a pneumatic tyre.
  • a depressor 104 is located in a generally central region within a pressure chamber 106 of the sensor 100. Depressor 104 depresses the tyre valve when the sensor 100 is screwed onto the threaded portion of the valve.
  • An initialisation stage then occurs. This stage monitors the internal pressure of the tyre and transmits a signal to receiver 108.
  • Sensors 100 are designed to determine the pressure of the tyres on which they are installed, store this initial pressure value in a memory and, subsequently, trigger a fault condition if/when the pressure change within the tyre is, for example, more than ⁇ 15% from the pressure originally measured. There is therefore no requirement for triggering of a fault condition, at predetermined absolute pressures. Thus there is no need to calibrate the sensors to an absolute pressure reading. The pressure variations are relative to the initial pressure obtained. 8
  • Sensors 100 a, b, c and d are located on each tyre of a vehicle 101.
  • the sensors 100 screw onto a tyre valve, effectively replacing its dust cap.
  • On a four-wheel vehicle the system is as shown in Figure 1, with a sensor attached to a valve of each wheel.
  • the sensor 100 can however be used on two wheel vehicles, or vehicles or trailers with more than four tyres.
  • the pressure transducers used in the sensors operate under micro-processor control.
  • Each sensor 100 is configured to transmit to a receiver 108 (or transceiver relay) an identification code when it is installed on a tyre.
  • Sensors 100 also measure and record a value corresponding to the pressure each one encounters when installed on a tyre. This value is stored in an electronic memory and is used for comparison with the tyre pressure during use, in order to determine whether the tyre pressure has changed by more than a predetermined amount. Preferably this change is monitored as a percentage of the first encountered pressure.
  • Transducers have an operating range from 0.5 to 10 bar and this enables the same sensors to be used on a wide range of vehicles.
  • a data processing unit 111 is provided in the receiver 108 in the cab of the vehicle, in a position where it can be viewed by a driver.
  • the data processing unit 111 is coupled to a display 110 which is used to display tyre deflation/inflation warning information to the driver.
  • the display 110 is preferably an alphanumeric display of, for example, the liquid crystal type. Thus it can provide other instructions and general information to a the driver. Alternatively a hand-held diagnostic device (not shown) may be used.
  • the display 110 also includes an audible alarm.
  • a micro-processor controller 10 sends a warning signal to (SAW) device 7 for transmission via transmitter 9.
  • the warning signal comprises an identification portion identifying the sensor and a tyre status portion, indicating the fault.
  • an identification signal may be a 16-bit coded signal which enables over 65,000 different sensor identification codes to be used.
  • 4 bits may be used to indicate the tyre's status and 12 bits for an identification ("id") code.
  • Sensors 100 are arranged to transmit, typically every 24 hours, an "OK" signal to the receiver if a "no fault” signal is detected.
  • the purpose of the "no fault” signal is to ensure that the receiver has information indicating that all sensors on a vehicle are still present and are operating correctly. Thus, if a fault develops on a unit or its battery is low, no "OK” signal is transmitted to the receiver 108 and this may indicate to a driver (via display 110) that there is a problem with a sensor on a particular tyre.
  • the sensor is capable of detecting faults with the sensor itself and to transmit to the receiver 108 a sensor fault signal.
  • the transmitter 9 transmits a fault signal repeatedly over a period of 30 seconds to receiver/transmitter 108. The transmission is then terminated to save the battery life in the sensor. Timings and duration of signal transmission can of course be varied as desired.
  • a depressor 104 urges a valve open as sensor 100 is screwed onto the threaded portion of a valve, by way of threaded portion 106.
  • Region 120 is an undercut between the body of sensor 100 and the collar region 103 which suirounds the threaded portion of the valve.
  • This undercut portion acts as a shareable collar. It has a predetermined shear strength and is dimensioned so as to shear on impact with a kerb, stone or other object. When this happens the sensor 100 and depressor 104 break away form the collar 103. Instantly an alarm signal is transmitted b ⁇ transmitter 109.
  • the tyre valve closes and nothing remains to depress the valve. This is an important safety feature of the invention, as otherwise if a 10 sensor were dislodged, by for example impact against a stone, the depressor may urge the valve to a part opened position hence air could leak and the tyre deflate.
  • Figures 3a and 3b show plan and sectional views of the cap 112 which holds all components in the sensor 100 and hermetically seals sensor 100 from egression of dirt and moisture. Projections or protuberances are shown which engage with recesses m the sensor body 100 to prevent tampe ⁇ ng. Removal of the cap 112, for example in order to replace battery 5, is by way of a special tool (not shown).
  • FIG 4 and 5 shows a general assembly of the sensor 100.
  • Transducer 12 (shown in greater detail in figures 8 and 9) is in the form of a generally circular symmetric disc and is supported in the sensor 100 by an O-nng seal 13. Current is returned, via Surface Acoustic Wave (SAW) transmitter.
  • SAW Surface Acoustic Wave
  • FIG. 7 shows a block diagram of a sensor including a micro-processor 119.
  • Micro-processor 119 supplies power to transducer and amplifier 120 and amplifier 122 to the transmitter 124 when required.
  • Cap 112 hermetically seals the sensor 100. Sp ⁇ ng 113 touches a metal contact in the cap 112 and completes a circuit. The cap is therefore positive and current, from batteries 5, is conducted to printed circuit board 8. Output of amplifier 122 is measured by an ADC within the micro-processor 119. The micro-processor 119 generates a modulated signal with transmitter 124 when power is applied. The values of the resistor/capacitor circuit in the oscillator 126 are an important part of the sensor and ensure that phase of clock pulses d ⁇ ft. This further enhances the secu ⁇ ty of the transmitter. The ADC leference voltage is taken from the or each battery.
  • Figures 8 and 9 show views of the transducer and elect ⁇ cal contacts of how this is connected with the printed circuit board (PCB). Contact pads 200 to 210 connect the 11 transducer to the PCB. A bridge arrangement (shown in Figure 9a) shows the equivalent electrical circuit.
  • Figures 10 a to d illustrate circuit board layouts used within the parts lists.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Measuring Fluid Pressure (AREA)

Abstract

L'invention concerne un capteur de pression pour pneu et un système d'alarme correspondant qui comprend un capteur (100) muni d'un collier fileté (106) et conçu pour être raccordé à la valve d'un pneu. Le capteur (100) comprend un transducteur (12) et un émetteur (9) scellés de façon étanche dans un boîtier. Un dépresseur (104) disposé sur le boîtier exerce une pression sur la valve pour ouvrir cette dernière. On peut relier le boîtier du capteur (100) au collier fileté (106) au moyen d'un collier (120) pouvant être cisaillé. Pendant l'utilisation, le capteur (100), lorsqu'il est raccordé pour la première fois à un pneu, obtient une valeur initiale de la pression du pneu et mémorise cette valeur initiale. Si la déviation de la pression du pneu par rapport à la valeur initiale dépasse une limite prédéterminée, par exemple, ± 15 %, un signal d'alarme est transmis à un récepteur disposé à l'intérieur du véhicule. Le signal d'alarme comporte une partie codée et une partie d'identification. On utilise de préférence un code de 12 bits pour assurer la sécurité suffisante et avoir à sa disposition environ 65000 codes d'identification différents. Comme le capteur est installé directement sur une valve et, par conséquent, ne nécessite aucun étalonnage, l'invention permet de résoudre les problèmes liés aux systèmes existants.
EP99906339A 1998-02-23 1999-02-23 Capteur de pression pour pneu et systeme d'alarme correspondant Withdrawn EP1085990A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
GBGB9803749.2A GB9803749D0 (en) 1998-02-23 1998-02-23 Tyre pressure sensor and warning system
GB9803749 1998-02-23
PCT/GB1999/000544 WO1999042308A1 (fr) 1998-02-23 1999-02-23 Capteur de pression pour pneu et systeme d'alarme correspondant

Publications (1)

Publication Number Publication Date
EP1085990A1 true EP1085990A1 (fr) 2001-03-28

Family

ID=10827421

Family Applications (1)

Application Number Title Priority Date Filing Date
EP99906339A Withdrawn EP1085990A1 (fr) 1998-02-23 1999-02-23 Capteur de pression pour pneu et systeme d'alarme correspondant

Country Status (5)

Country Link
EP (1) EP1085990A1 (fr)
AU (1) AU2631099A (fr)
CA (1) CA2324411A1 (fr)
GB (1) GB9803749D0 (fr)
WO (1) WO1999042308A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107225920A (zh) * 2017-06-02 2017-10-03 国动物联网技术（上海）有限公司 一种LoRa无线胎压监测系统及监测方法
US11804118B2 (en) 2022-03-01 2023-10-31 Honeywell International Inc. Aspirating smoke detector discreet sample point

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2358949A (en) * 2000-02-03 2001-08-08 Transense Technologies Plc Tyre monitoring system
US6993962B1 (en) * 2005-03-11 2006-02-07 Yueh-Ying Ko Electronic wireless tire pressure monitoring apparatus
GB2572347B (en) * 2018-03-27 2020-05-27 Wheely Safe Ltd Auto-calibrating tyre pressure monitoring system

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL6813087A (fr) * 1968-07-09 1970-01-13
DE3930480A1 (de) * 1989-09-12 1991-03-14 Rainer Achterholt Eine ein druckabnahmesignal erzeugende ventilkappe fuer einen luftreifen
GB2279169B (en) * 1993-06-17 1997-04-23 Simon John Ford A tyre pressure alarm device
AUPN133795A0 (en) * 1995-02-23 1995-03-16 Cohen, Phillip Tyre pressure telemetry system
US5604481A (en) * 1995-03-08 1997-02-18 Bai Chj Industrial Co., Ltd. Tire pressure detector

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9942308A1 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107225920A (zh) * 2017-06-02 2017-10-03 国动物联网技术（上海）有限公司 一种LoRa无线胎压监测系统及监测方法
US11804118B2 (en) 2022-03-01 2023-10-31 Honeywell International Inc. Aspirating smoke detector discreet sample point

Also Published As

Publication number Publication date
GB9803749D0 (en) 1998-04-15
WO1999042308A1 (fr) 1999-08-26
CA2324411A1 (fr) 1999-08-26
AU2631099A (en) 1999-09-06

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