Telemetry unit

摘要

A telemetry unit (100) is provided for mounting to the inside of a pneumatic tyre, which includes sensors for measuring the pressure and temperature within the tyre and an RF transmitter for transmitting measured data to an on-board display remote location. The unit (100) includes a piezoelectric element (114) supported in a housing (112) with an actuator (136) arranged for contact with the element (114), to deflect the element (114) in response to external forces acting on the actuator (136) during rotation of the tyre. For every rotation of the tyre, cyclic pulses of electrical charge are generated by the deflection of the element (114). The unit (100) includes control means which controls the consumption of stored charge when measuring and transmitting data and is arranged to vary the rate of transmission of data from the unit (100) in dependance on the rotary speed of the tyre.