Patent ID: 6580241
Filing Date: 2003-06-17
Classification: H02H

Abstract:
A method of detecting pinching of an object in a power window device having a motor to open and close a window, a motor drive unit to drive the motor, a pulse generator to generate a pulse as the motor rotates, a memory, a micro control unit to control respective units, and a window open/close manual switch, the method comprising:dividing a travel extent of the window into a plurality of travel regions; detecting motor torque values in sequence when opening or closing the window under control of the micro control unit, for each travel region: determining a base median value representing a motor torque value when no pinching occurs, a base tolerance value which is a tolerance value of increased motor torque value caused by pinching, adding the base median value and the base tolerance value to calculate a base value, and storing the base value in the memory; calculating a corrected base median value by averaging motor torque values detected in an immediately preceding travel region, calculating a rate of change by dividing the corrected base median value by a corresponding base median value in the immediately preceding travel region, calculating a correction coefficient in a present travel region from a first equation that includes the rate of change, calculating a corrected base value in a middle point of the present travel region by applying the correction coefficient in a second equation, and connecting corrected base values at the middle points of adjacent travel regions by a straight line and setting corrected base line values other than at the middle point of the particular travel regions; comparing the motor torque value detected after setting the corrected base value with corrected base value; and determining that pinching exists when the motor torque value exceeds the corrected base value and stopping the motor or rotating the motor in a reverse direction in response to determining that pinching exists.