Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
  • G01M17/00—Testing of vehicles
  • G01M17/007—Wheeled or endless-tracked vehicles
  • G01M17/02—Tyres
• • 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
• • 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
  • B60C23/005—Devices specially adapted for special wheel arrangements
  • B60C23/009—Devices specially adapted for special wheel arrangements having wheels on a trailer
• • 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
  • B60C23/0401—Signalling devices actuated by tyre pressure mounted on the wheel or tyre characterised by the type of alarm
• • 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
• • 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
  • B60C23/0474—Measurement control, e.g. setting measurement rate or calibrating of sensors; Further processing of measured values, e.g. filtering, compensating or slope monitoring
• • 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
  • B60C23/0474—Measurement control, e.g. setting measurement rate or calibrating of sensors; Further processing of measured values, e.g. filtering, compensating or slope monitoring
  • B60C23/0476—Temperature compensation of measured pressure values
• • 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
  • B60C23/0483—Wireless routers between wheel mounted transmitters and chassis mounted receivers

Definitions

• the present invention relates to a system for monitoring the pressure of tyres in a wheeled vehicle.
• the invention relates to a tyre pressure monitoring system employing individual battery-powered pressure sensors associated with each tyre for transmitting coded information to a receiver mounted within the vehicle to provide information about the condition of the tyres to a driver of the vehicle.
• a battery-powered tyre pressure sensor comprises: a pressure transducer for sensing a pressure of a tyre and providing a tyre pressure signal; a transmitter: a signai processor connected to the pressure transducer for providing a signai dependent on the tyre pressure signal to the transmitter: a timing circuit connected to the signal processor which is configured to automatically switch the tyre pressure sensor on periodically for a predetermined interval to measure the tyre pressure and switch off the tyre pressure sensor at all other times to conserve battery power, in which the timing circuit comprises a timer and a switch, the timer being configured to periodically actuate the switch and thereby connect the pressure sensor to the battery to turn the tyre pressure sensor on for said predetermined interval.
• the tyre pressure sensor of the present invention is suitable for all types of vehicles, but is especially suited for fitting to commercial vehicles such as buses, coaches, trucks, and lorries.
• the pressure sensor monitors the pressure of a tyre and gives the vehicle driver eariy warning of any deflation, thereby improving safety, as well as reducing tyre wear and improving fuel economy.
• An important aspect of the present invention is that the pressure sensor is only switched on periodically under the control of a timer to sample the tyre pressure. This feature allows battery power to be conserved and therefore effectively extend the life of the battery or otherwise allow a smaller battery to be used.
• the pressure sensor further comprises a non-voiatile memory device for storing an identification code used to identify transmissions from the pressure sensor.
• the non-volatile memory device also stores calibration information which is used to determine an accurate tyre pressure.
• each pressure sensor may be tested at atmospheric pressure, maximum rated pressure, and at several points between, and the results of the calibration routine stored in the non-volatile memory device as variables which characterize the response of the pressure sensor.
• the advantage of a non-voiatile memory is that data is not lost when the pressure sensor is switched off in the
• the sensor unit further comprises a temperature transducer connected to the signal processor to provide a temperature signal to the signai processor, wherein the signal processor is adapted to apply a temperature compensation to the tyre pressure signal in dependence on the temperature signal.
• the signai processor to correct the output of the pressure transducer to ensure accuracy over a range of. for example. -40 °C to -r-60°C.
• this information can be transmitted by the pressure sensor to warn the vehicle driver that road conditions may be hazardous.
• the signal processor is a microcontroller having an embedded computer program for controlling the operation of the pressure sensor.
• the microcontroller is configured to record battery voltage and operating temperature each time it makes a pressure measurement and, when necessary, encode this information together with the pressure sensor identification code for transmission via the transmitter.
• the transmitter comprises a surface acoustic wave (SAW) resonator.
• SAW surface acoustic wave
• Suitable radio frequencies for use in the United Kingdom include 418 MHz and 433 MHz in accordance with the radio specifications for MPT 1340 of the Radio Communications Agency. These frequencies are currently licence exempt.
• the pressure sensor is adapted to be screwed onto the valve stem of a venicie tyre. This allows the pressure sensor to be retro-fitted to existing vehicles.
• the pressure sensor may be adapted for mounting
• the pressure sensor is configured so that it does not make any transmissions until it is connected to an inflated tyre. This feature ensures that battery power is conserved during transport and storage of the pressure sensor before fitting to a tyre.
• the cab unit comprising: a receiver for detecting transmissions from the respective transmitters of the tyre pressure sensors: and. a display for providing a driver with information about the tyres on the vehicles in dependence on the received transmissions from the pressure sensors.
• a transponder unit for use in a remote tyre pressure monitoring system for a vehicle which includes a plurality of remote tyre pressure sensors connected to respective tyres, wherein each pressure sensor is adapted to transmit a signal with information about the condition of its respective tyre
• the transponder unit comprising: a receiver for receiving the transmitted signals from the individual pressure sensors: a signal processor for processing signals from the pressure sensors and generating a coded signal for transmission which identifies the transponder unit and tyre location: and. a transmitter or transmitting the coded signal to a remote receiver where information can
• the transponder unit of the present invention allows a cab unit within a vehicle cab to distinguish between transmissions from the remote tyre pressure sensors of a trailer and other pressure sensors without requiring the driver to individually register each pressure sensor of the trailer whenever the vehicle cab and trailer are first connected. This is useful since a lorry driver may change trailer frequently.
• the cab unit within the vehicle cab is able to "learn" the unique identifier for the trailer transponder unit so that it can recognise subsequent transmissions forwarded by the transponder unit which encode information from the tyre pressure sensors connected to the trailer tyres.
• a remote tyre pressure monitoring system comprises a transponder unit according to the third aspect of the present invention in combination with a cab unit, wherein the cab unit comprises: a receiver for receiving the coded signal from the transponder unit: a signal processor for detecting and decoding the coded signal: and. a display for providing the driver with information about the condition of the tyres associated with the transponder unit.
• the remote tyre pressure monitoring system comprises a vehicle trailer on which
• the transponder unit is mounted.
• the remote tyre pressure sensors are tyre pressure sensors in accordance with the first aspect of the present invention.
• the present invention combines simplicity of operation with the most advanced solid-state electronic design. It is proposed that the valve dust cap for each wheei of a vehicle is replaced by a pressure sensor in accordance with the present invention which monitors the tyre pressure and reports to a computer controlled unit in the vehicle cab. Should, for example, the pressure in any tyre drop by more than say 12.5 % . a radio signal is then sent to a display in the cab to warn the driver as to which of his tyres is losing air. The driver then has time to act before the tyre is damaged, thereby saving on tyre wear and fuel, and perhaps avoiding the expensive results of complete tyre failure.
• a radio transponder unit mounted on the front of the trailer relays messages from pressure sensors connected to the trailers wheels to the vehicle cab.
• the system of the present invention is as easy to fit as a car radio.
• the cab unit is pre-programmed to accept the new set of trailer wheels but will not respond to pressure sensors from other rigs.
• the pressure sensors have a long life, typically up to three years. This is achieved by the use of the timing circuit which ensures that the pressure sensor is switched off most of the time. Typically, each pressure sensor will draw a current of significantly less than 1 ⁇ A between pressure measurements, and draw only a small current of the order of 4.5 mA when switched on.
• the present invention will lead to significant savings in running costs for commercial vehicle operators: savings within the first year which should represent four times the purchase price. Added to this are the safety advantages, greater reliability, and reduced levels of tyre maintenance.
• FIG. 1 is a block diagram of a tyre pressure monitoring system according to the present invention:
• FIG. 2 is a block diagram of an example of a tyre pressure sensor for use in the tyre pressure monitoring system oi Figure 1 :
• Figures 3 shows a circuit implementing a temperature transducer, a pressure transducer and a reference voltage generator for use in the tyre pressure sensor of Figure 2:
• Figure 4 shows a timing circuit implementing a timer and switch for use in the tyre pressure sensor of Figure 2;
• Figure 5 shows an example of a transmitter and antenna circuit for use in the tyre pressure
• Figure 6 shows an example of a non-volatile memory device for use in the tyre pressure sensor of Figure 2:
• Figure 7 shows an example of a microcontroller for use in the tyre pressure sensor of Figure Figure 8 is a riow chart showing the sequence of operations for a calibration routine:
• Figure 9 is a now chart showing the sequence or operations for a tyre pressure measurement
• Figures 10 and 11 show a cab unit for use in the tyre pressure monitoring system of Figure 1 : and.
• Figure 12 is a block diagram of a transponder unit for use in the tyre pressure monitoring
• Figure 1 shows an example of a tyre pressure monitoring system according to the present invention.
• the system is suitable for mounting on the tyres of a vehicle such as a truck, bus. or coach, and also on lorries which have a vehicle cab (tractor) and a separate trailer.
• the system includes a cab unit 1 and a first set of tyre pressure sensor units 2 j to 2 S .
• the system includes a trailer transponder unit 3 and a second set of tyre pressure sensor units 4 j to 4 3 associated with a trailer.
• each of the sensor units 2, to 2 2 and 4, to 4 3 has a radio transmitter for transmitting a coded signal which carries information relating to the condition of a respective tyre to a receiver in the cab unit 1.
• the information is used to inform the vehicle driver about the pressure and temperature of each of the tyres by way of an audio/-visual display forming part of the cab unit 1.
• the transponder unit 3 is designed to be mounted on a lorry trailer and it detects transmitted signals from each of the second set of sensor units 4 j to 4-, associated with respective tyres of the trailer.
• the transponder unit 3 transmits a coded signal to the cab unit 1 containing information about each ot the traiier tyres.
• the cab unit 1 is adapted to decode the transponder signai and distinguish between the transponder signai and any other signai so that the driver can be aêtd or any
• FIG. 2 shows a schematic representation of an example of a battery-powere ⁇ tyre pressure sensor in accordance with the present invention.
• the pressure sensor comprises a pressure transducer 10. a temperature transducer 11. a reference voltage generator 12. a transmitter 13 and a non-volatile memory device 14. all connected to a microcontroller 15.
• the device also houses a battery 16 as the power suppiv.
• the pressure sensor is periodically activated by a timing circuit 17.
• the timing circuit 17 comp ⁇ ses a switch 18 and a timer 19.
• the timer 19 is configured to cause the pressure sensor to sample periodically the pressure of the tyre to which the device is connected, but otherwise disconnect the other elements of the pressure sensor from the battery 16 at all other times to conserve battery power.
• a calibration switch 20 is provided to calibrate the pressure sensor before shipping, as will be described below.
• the pressure sensor is implemented on a printed circuit board and, together with the battery, sealed with a housing adapted to be screwed onto a tyre valve stem
• the pressure transducer 10 is arranged to measure the pressure of the tyre and provide an output (PRESSURE) to the microcontroller 15.
• a suitable device is a piezo-resistive sensor, the resistivity of which changes with changes in pressure.
• An example of a suitable circuit which implements a pressure transducer is shown in Figure 3.
• the .emperatur ⁇ transducer 11 is configured to measure the temperature of the air surrounding the sensor ana provide an output (TEMP) to the microcontroller :5. This out ⁇ ut signal is used to provide a temDerature compensation to the pressure signai output
• the temperature signal may also be used to provide a driver of the vehicle with information about related driving conditions.
• An example of a suitable circuit which implements a temperature sensor is shown in Figure 3.
• the reference mousseage generator 12 is configured to generate a stable reference voltage signal (VREF) which is provided as an input to the microcontroller 15.
• the microcontroller 15 compares the reference voltage with the battery voltage (VOLTS) and generates an output signai dependent on this comparison. If the battery voltage is less than the reference voltage this means that a new battery is required and a signal is generated to convey this to the driver. Furthermore, in this event, the frequency of the sampling of the tyre pressure may automatically be reduced to prolong the life of the battery until a new pressure sensor or battery can be fitted.
• An example of a suitable circuit which implements a reference voltage generator is shown in Figure 3.
• the timing circuit 16 comprises a switch 18 and a timer 19.
• the timer 19 runs all the time and periodically engages the switch 18 to start a pressure measurement cycle. At all other times the remaining components of the pressure sensor are switched off to conserve battery power. Furthermore, as described above, the frequency at which the pressure sensor is switched on is dependent on the battery voltage. When this starts to fall, the microcontroller 15 generates a warning message in the next routine status transmission and at the same time reduces the sensor sampling frequency to conser/e the remaining
• the battery 16 is a lithium device having a diameter of 16mm with a rating of typically 60-70 mAh.
• the function of the radio transmitter 14 is to send messages from each tyre pressure sensor to a receiver in either the cab unit 1 of the vehicle cab or in the transponder unit 3 of a trailer.
• the transmitter 14 transmits the signal generated by the microprocessor 15 at a frequency of either 418 MHz or 433 MHz in accordance with the MPT1 340 specification. These frequencies are currently licence exempt.
• a suitable type of transmitter 15 is based on a surface acoustic wave (SAW) device. An example of a suitable circuit can be seen in Figure 5.
• SAW surface acoustic wave
• the non-volatile memory 15 stores information about the tyre and also contains a unique pressure sensor identification code, programmed during manufacture as part of a calibration process, as will be described below.
• a non-volatile memory device 15 in the pressure sensor is that when the sensor unit is switched off information is not lost. This is important since it enables power to be completely shut down to the main components of pressure sensor in the interval between sensor readings.
• An example of a suitable memory device is shown in Figure 6.
• the microcontroller 15 accepts a signal from each of the pressure transducer 10, the temperature transducer 11 and the reference voltage generator 12. It processes these signals and provides an outDut signai to the transmitter :4 which includes the unique sensor identification code for the pressure sensor.
• An example of a suitable microcontroller is
• the microcontroller 15 receives a signai from the pressure transducer 10 it aiso records the battery drunkage and temperature. Thus, with the appropriate programming, it is able to determine an accurate pressure measurement for the tyre. The tyre pressure measurement is compared with a stored (notionally correct) reference vaiue and if the tyre pressure is determined to deviate from this by a predetermined amount a message is generated by the microcontroller 15 for transmission. In addition to. or even in the absence of. any message relating to the condition of the tyre or driving conditions, the microcontroller 15 is arranged periodically to generate an identification message for transmission which serves to confirm that the pressure sensor remains operational. Failure to transmit such a message will eventually cause a warning to be displayed on the cab unit 1 to indicate to the driver that the pressure sensor has either failed or been removed.
• a computer program is embedded within the microcontroller 15 which controls the operation of the pressure sensor.
• the computer program is executed when power is applied to the microcontroller 15 by the timing circuit 16, initiated by the timer 19.
• the computer program contains two distinct parts. One part executes during a calibration cycle and the other part executes at all other times.
• the microcontroller 15 decides which part to execute by examining the state of the MODE input pin (pin 7 in Figure 7). As shown in the pseudocode below and the flow chart of Figure 8. during calibration the MODE pin is initially set to a low state by a calibration jig (not shown). At all other times it is kept in a high state. Once calibration commences the MODE pin is used as a bi-directional path for signals between the microcontroller 15 and the calibration jig.
• Step YY Store the digital value required to achieve the standard output in the Non- Volatile Memory
• the MODE pin is driven by the calibration jig (not shown) which provides manufacturing date code, the identification code for the unit, an initial reference pressure of zero, multi- count vaiue. percentage pressure band limits, battery condition flag and other information that may be required to be stored. This data is routed to and stored in the non-volatile memorv.
• the pseudo code beiow and flow chart of Figure 9 details the normal operation of the pressure sensor:
• FIG 10 shows a schematic representation of an exam ⁇ ie o a cab unit i suitable for use in the tyre pressure monitoring system.
• the cab unit 1 comprises a receiving antenna 30. a microcontroller 31. a driver ' s display 32 to disDiay information about the tyres to the driver, and a memory 33.
• the microcontroller 31 is able to distinguish between signals and identify, by way of its unique identification code, which pressure sensor or transponder unit is sending each signal. In normal operation, each pressure sensor periodically transmits an "all's-weH" signal. If the cab unit 1 detects two consecutive missing signals from the same unit, an LED will flash to tell the driver to check that tyre.
• the cab unit 1 can display warnings whenever any tyre is suffering from any of low pressure, low temperature, low battery or a missing sensor unit.
• the drivers cab display 32 is shown in detail in Figure 1 1.
• the drivers cab display 32 has the following items: - a two digit wheel number indicator 40 with two small adjacent LED indicators.
• LED illuminates when the wheel number displayed relates to the cab and the other illuminates when the wheel number relates to a trailer: further LEDs 41 to 44 provide "low temperature”, “low pressure”, “low battery”, and “unit missing” warnings, respectively; and. - a switch 45 with positions.
• LEARN CAB LEARN TRAILER and NORMAL, with small LEDs to indicate a teaching process (to be described below) is being carried out.
• An acoustic sounder (not shown) is included in the cab unit 1 and sounds for ten seconds after a warning message is received and every five minutes thereafter. When the ignition is turned on the sounder makes a short chirp. If a warning message has been received during driver absence it will sound for ten seconds. Power is supplied continuously by the
• a “cancel” button (not shown) is also provided which can disable a warning entry until the next ignition off-on cycle.
• FIG 12 shows a schematic representation of an example of a transponder unit 3 for a trailer.
• the transponder unit comprises a receiver 51. a microcontroller 52 and a transmitter 53.
• the receiver 51 periodically receives signals transmitted by individual tyre pressure sensors and couples the signals to the microcontroller 52.
• the microcontroller 52 processes a signal and generates a new message which incorporates a unique identification code associated with the transponder unit 3 as a header which is transmitted by the transmitter 53 and which can be detected by the cab unit. This identification code, as with the pressure sensors, is stored in a memory 54.
• the driver When fitting pressure sensors to a trailer, the driver selects a corresponding LEARN TRAILER feature on the trailer transponder unit 3 (not shown). The driver then walks around the trailer in the same manner as for a cab unit, ⁇ ttmg each of the wheels in turn with a pressure sensor so that the trailer transponder unit 3 knows how many wheels are present and their identification codes.
• the driver selects the LEARN TRAILER feature on the cab unit I so that any previous information relating to trailers is deleted.
• the brake pedal is first depressed the trailer transponder unit 3 recognises that it should identify itself to the cab unit 1 because this is the first time it has had power supplied and the brake light line is active. It then transmits its unique identification code to the cab unit 1 to identify itself as a new trailer. This identification code for the trailer is then stored in the cab unit 1.
• the driver subsequently selects the NORMAL feature and the system is now ready for use.
• the "learn trailer" step can be automated so that the driver does not even need to select this on the cab unit - the registration process is carried out automatically after ignition is switched on.
• the cab unit 1 receives transmissions from the cab ' s wheels, which are recognised, and trailer wheel messages which are ignored.
• the trailer transponder unit 3 receives transmission from its own wheels, which are recognised, and the cab wheels which are ignored.
• information from the trailer wheels is stored in the trailer transponder unit 3 and warning and other messages from the trailer transponder unit 3 are relayed to the cab with a message header so that they are recognised by the cab. It is proposed that warning messages are passed to the cab immediately by the transponder unit 3 whereas routine "all's well" messages are oniy sent periodically.
• tyre pressure monitoring system of the present invention It is possible to build on the tyre pressure monitoring system of the present invention to provide a complete tyre management system for a fleet operator.
• the idea is that as each vehicle returns to a depot, the cab unit is automatically interrogated to determine the condition of each tyre.
• the vehicle depot keeps a computer database which provides a record of the vehicle movements and a list of which tyres on which vehicles need attention. In this way, the need to rely on driver trip reports is reduced.
• the depot system could also be programmed to interrogate vehicles as they leave a depot as a double check that any defective tvres have been dulv corrected.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Computer Networks & Wireless Communication (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Measuring Fluid Pressure (AREA)
• Arrangements For Transmission Of Measured Signals (AREA)

Applications Claiming Priority (3)

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• 1998
  • 1998-05-22 GB GBGB9811154.5A patent/GB9811154D0/en not_active Ceased
• 1999
  • 1999-05-21 EP EP99922387A patent/EP1077817A1/en not_active Withdrawn
  • 1999-05-21 KR KR1020007013111A patent/KR20010052386A/ko not_active Application Discontinuation
  • 1999-05-21 AU AU39481/99A patent/AU3948199A/en not_active Abandoned
  • 1999-05-21 JP JP2000550695A patent/JP2002516399A/ja active Pending
  • 1999-05-21 CN CN99808937A patent/CN1310674A/zh active Pending
  • 1999-05-21 WO PCT/GB1999/001625 patent/WO1999061265A1/en not_active Application Discontinuation
  • 1999-05-21 CA CA002332805A patent/CA2332805A1/en not_active Abandoned

Non-Patent Citations (1)

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