This PIC18F252-based project allows you to measure the torque in an automobile drive shaft. Output data from the device can be sent to PC or vehicle data recording system through RS-232 interface. To calculate horsepower, output data need to be combined with RPM measurements from the data recording system. The project consists of two main parts, sensor unit, which attaches to the driveshaft, and the receiver unit, which provides the serial output signal. The sensor unit is battery powered and communicates with the receiver via a 433 MHz RF data link. The receiver unit is powered by the vehicle electrical system.
The sensor unit is contained in a cylindrical housing split along its axis to allow attachment without access to the driveshaft end. When the driveshaft experiences torsion it is transferred to the housing endplates. The inboard endplate contains a permanent magnet which is mounted against a Hall-effect sensor on the sensor plate. Since the sensor plate is attached to the outboard end plate it moves with it. The resulting angular deflection between the magnet and the sensor produces a signal which is proportional to the driveshaft torque. This signal is processed by the circuitry of the MCU PCB mounted axially between the endplates in the upper housing half.
Horse power monitor
Project Detail and Documentation