Patent ID: 9115806
Filing Date: 2015-08-25
Classification: F16H

Abstract:
1. A control device for controlling an automatic transmission including a frictional engagement element adapted to transmit rotation by being engaged by a supply of oil and to cut off transmission of the rotation by being released by discharging the oil, comprising: a first hydraulic pressure control unit structured to be mechanically coupled to a select lever and to supply and discharge oil to and from the frictional engagement element according to an operation position of the select lever; a range signal output unit adapted to output a range signal corresponding to the operation position of the select lever; an abnormality determination unit adapted to determine an abnormality of the range signal output unit based on the range signal; and a second hydraulic pressure control unit structured to be arranged in series with the first hydraulic pressure control unit and to supply and discharge the oil to and from the frictional engagement element in accordance with the range signal, the second hydraulic pressure control unit being disposed between the first hydraulic pressure control unit and the frictional engagement element; wherein the first hydraulic pressure control unit forms an oil path enabling the supply of oil to the frictional engagement element when the select lever is located in a travel range or between the travel range and a non-travel range adjacent to the travel range and forms an oil path to discharge the oil from the frictional engagement element when the select lever is located in the non-travel range, the non-travel range being an N-range or a P-range; wherein the abnormality determination unit determines that a signal output from the range signal output unit is abnormal when a signal corresponding to an intermediate position between the travel range and the non-travel range is continuously output from the range signal output unit for an abnormality determination time, cancels the abnormality determination when only a travel range signal is output from the range signal output unit after the abnormality is determined, and maintains the abnormality determination when only a non-travel range signal is output from the range signal output unit after the abnormality is determined; and wherein the second hydraulic pressure control unit forms an oil path enabling the supply of the oil to the frictional engagement element when the abnormality is determined by the abnormality determination unit or when only the travel range signal is output and forms an oil path to discharge the oil from the frictional engagement element when a time during which the signal corresponding to the intermediate position between the travel range and the non-travel range is output is shorter than the abnormality determination time or when only the non-travel range signal is output.