Movement interval measurement apparatus for checking operating status of vehicle power transmission apparatus unaffected by temperature

A movement distance measurement apparatus for confirming an operating state of a power transmission device for automobiles when a detection target object operates, wherein

• in the power transmission device provided with a drive shaft including an engaging structure, a movable propulsion shaft engaged with the drive shaft to transfer power, a detection target object of a metal material connected to the propulsion shaft to move together, an internal operator for transferring an operating force to the propulsion shaft, and an actuator including an actuator driving source to control the power transmission device for automobiles,
• the movement distance measurement apparatus comprises:
• a square wave generator for generating a square wave of a specific frequency;
• a low-pass filter for converting a square wave generated by the square wave generator into a sine wave or removing noise components excluding a reference frequency component of the square wave;
• a tuned amplifier configured to amplify a signal passing through the low-pass filter, include a resonance circuit including a sensing coil, and provide an output signal including a resonance frequency, which changes in response to changes in the distance between the detection target object and the sensing coil, and the output voltage of the resonance circuit that changes;
• a DC restorer for removing a bias voltage from the output signal of the tuned amplifier to output only signals of AC component;
• a maximum value detection unit for detecting a maximum voltage value from the output signal of the DC restorer;
• a diode voltage detection unit for detecting as many second diode voltage values as the number of diodes used in the DC restorer and the maximum value detection unit in order to remove a first diode voltage value included in the maximum voltage value output from the maximum value detection unit;
• an AD converter for converting the maximum voltage value of the maximum value detection unit and the second diode voltage value of the diode voltage detection unit into digital signals and outputs the converted signals;
• and
• a control unit for removing the effect of diode voltage according to temperature change by removing the first diode voltage value included in the digital-converted maximum voltage value using the digital-converted second diode voltage value, and outputting a moving distance value of the detection target object by comparing the maximum voltage value, from which the first diode voltage value is removed, with previously stored comparison data.