METHOD FOR SENSING REVERSE ROTATION OF ENGINE IN VEHICLE USING TOOTH PERIOD RATIO OF CRANKSHAFT

A method for sensing reverse rotation of an engine in vehicle includes: detecting tooth period ratios using a crankshaft angle detection sensor and storing the detected tooth period ratios in a buffer of an electronic control unit (ECU); calculating a tooth period ratio between a measured tooth period and a tooth period measured just before thereof; determining whether the tooth period ratio is greater than a first reference value; updating the tooth period value stored in the buffer by measuring the recent tooth period if the tooth period ratio is greater than the first reference value; calculating the tooth period ratio using the updated tooth period value; and determining a reverse rotation state of the engine by checking whether the change shows a predetermined pattern after a change in the value of the tooth period ratio is observed.