Patent ID: 7899593
Filing Date: 2011-03-01
Classification: G01M

Abstract:
1. An abnormality diagnosis apparatus for an automatic transmission having: a lock-up mechanism that is able to mechanically couple an input shaft and an output shaft of a torque converter to each other; a shift mechanism that changes a rotation speed of the output shaft of the torque converter; and a control mechanism that controls the lock-up mechanism and the shift mechanism, the automatic transmission being adapted to operate in a slip state in which the lock-up mechanism mechanically couples the input shaft and the output shaft to each other such that the input shaft and the output shaft are able to rotate relative to each other in a slip region; a full lock-up state in which the lock-up mechanism mechanically couples the input shaft and the output shaft directly to each other in a full lock-up region; and a lock-up release state in which the lock-up mechanism releases mechanical coupling between the input shaft and the output shaft in a lock-up release region, the abnormality diagnosis apparatus comprising: a full lock-up forcing portion that shifts the lock-up mechanism from the slip state or the lock-up release state to the full lock-up state in a forcible lock-up region that is formed outside of the full lock-up region; a full lock-up determination portion that determines whether the lock-up mechanism is in the full lock-up state in the forcible lock-up region; a shift failure determination portion that determines whether the lock-up mechanism has failed to be shifted from the full lock-up state to the desired slip state; and a shift failure counting portion that counts the number of times failure of shifting has been detected by the shift failure determination portion, wherein the full lock-up forcing portion forcibly shifts the lock-up mechanism from the slip state to the full lock-up state when the number of times counted by the shift failure counting portion exceeds an allowable number of times.