Tire pressure and temperature measurement system

Claim 1

A method of measuring vehicle wheel tire inflation pressure in real time comprising the steps of: exposing a pressure cell to pressure of gas inflating the wheel tire; transmitting a power signal from the vehicle to the wheel; conditioning the power signal to obtain a signal suitable for energising the pressure cell; energising the pressure cell; sensing inflation pressure using the pressure cell; outputting a first signal from the pressure cell representative of tire inflation pressure acting on the pressure cell; monitoring the resistance of the pressure cell to obtain a second signal representative of the temperature of the pressure cell; converting the first and second signals to digital signals; applying the digital signals to address locations in a look-up table holding calibrated pressure cell outputs over a range of pressure and temperature; processing data from the look-up table to obtain a corrected real time pressure value; and transmitting a signal representative of the corrected real time pressure value to the vehicle.

Claim 2

A method of measuring vehicle wheel tire inflation pressure in real time comprising the steps of: exposing a pressure cell to pressure of gas inflating the wheel tire; transmitting a power signal from the vehicle to the wheel; conditioning the power signal to obtain a signal suitable for energising the pressure cell; energising the pressure cell; sensing inflation pressure using the pressure cell; outputting a first signal from the pressure cell representative of tire inflation pressure acting on the pressure cell; monitoring the resistance of the pressure cell to obtain a second signal representative of the temperature of the pressure cell; converting the first and second signals to digital signals; applying the digital signals to address locations in a look-up table holding calibrated pressure cell outputs over a range of pressure and temperature; processing data from the look-up table to obtain a corrected real time pressure value; and transmitting a signal representative of the corrected real time pressure value to the vehicle.

Claim 8

A system for real time measurement of vehicle wheel tire inflation pressure, having a pressure sensor to be mounted on a rotary part of a vehicle wheel whose inflation pressure is to be measured, said pressure sensor comprising: a pressure cell for generating first signals representative of the inflation pressure in said vehicle wheel; and an electronic module, connected to said pressure cell, including a signal conditioning electrical circuit for conditioning a power signal transmitted to said rotary wheel part and outputting a signal for energising said pressure cell, an electrically-erasable-programmable-read-only memory (EEPROM) for storing, in the form of a look-up table, values of pressure and temperature signals output by said pressure cell when calibrated over a range of pressure and temperature, means for monitoring the resistance of said pressure cell and outputting second signals representative of the temperature of said pressure cell, and a pressure cell signal output processing electrical circuit receiving said first signals from said pressure cell and said second signals from said monitoring means, said processing electrical circuit including means for converting said first and second signals to digital signals, means for addressing locations in said EEPROM look-up table, means for processing data from said look-up table to obtain a corrected real time pressure value, and means for converting the corrected real time pressure value to binary data for transmission to the vehicle.

Claim 9

A system for real time measurement of vehicle wheel tire inflation pressure, having a pressure sensor to be mounted on a rotary part of a vehicle wheel whose inflation pressure is to be measured, said pressure sensor comprising: a pressure cell for generating first signals representative of the inflation pressure in said vehicle wheel; and an electronic module, connected to said pressure cell, including a signal conditioning electrical circuit for conditioning a power signal transmitted to said rotary wheel part and outputting a signal for energising said pressure cell, an electrically-erasable-programmable-read-only memory (EEPROM) for storing, in the form of a look-up table, values of pressure and temperature signals output by said pressure cell when calibrated over a range of pressure and temperature, means for monitoring the resistance of said pressure cell and outputting second signals representative of the temperature of said pressure cell, and a pressure cell signal output processing electrical circuit receiving said first signals from said pressure cell and said second signals from said monitoring means, said processing electrical circuit including means for converting said first and second signals to digital signals, means for addressing locations in said EEPROM look-up table, means for processing data from said look-up table to obtain a corrected real time pressure value, and means for converting the corrected real time pressure value to binary data for transmission to the vehicle.