초록 ▼

A direct-coupling control method capable of improving fuel efficiency by performing slip direct-coupling control of a torque converter, in which a driving force transmission of an automatic transmission is operated under an approximate direct-coupling condition that permits slight slippage of the to

A direct-coupling control method capable of improving fuel efficiency by performing slip direct-coupling control of a torque converter, in which a driving force transmission of an automatic transmission is operated under an approximate direct-coupling condition that permits slight slippage of the torque converter, in a predetermined operating range of the automatic transmission such as a low speed range thereof, and capable of positively detecting and preventing direct-coupling vibration caused by deterioration of hydraulic oil or the like. In the slip direct-coupling control, an occurrence of direct-coupling vibration is detected when a variation of a slip amount changing beyond predetermined upper and lower limit values is found a predetermined number of times during a predetermined period of time, or when a variation in the rotational rate of the output shaft of the torque converter still continues even after the slip direct-coupling control is interrupted for the reason that the rotational rate has varied beyond a permissible range. Upon detection of the direct-coupling vibration, the slip direct-coupling control is inhibited.

대표청구항 ▼

A direct-coupling mechanism control method for an automatic transmission in a vehicle including a driving force transmission installed between an internal combustion engine and an automatic transmission and which has an input-side driving force transmitting element coupled to a side of the internal

A direct-coupling mechanism control method for an automatic transmission in a vehicle including a driving force transmission installed between an internal combustion engine and an automatic transmission and which has an input-side driving force transmitting element coupled to a side of the internal combustion engine, an output-side driving force transmitting element coupled to the automatic transmission, and a direct-coupling mechanism for permitting the input and output-side driving force transmitting elements to be coupled to each other, for controlling a coupling state of the direct-coupling mechanism to be in any one of a fully direct-coupled state, in which the input and output-side driving force transmitting elements are integrally coupled to each other; a slip direct-coupled state, in which torque transmission is permitted such that a rotational speed difference between the input-side and output-side driving force transmitting elements falls within a predetermined range; and a non-direct-coupled state, in which the fully direct-coupled state and the slip direct-coupled state are released and in which torque transmission, through hydraulic oil, between the input and output-side driving force transmitting elements is permitted, the direct-coupling mechanism control method comprising the steps of: (a) determining whether or not the internal combustion engine is running in at least one of a low rotation speed area and a decelerating area and controlling the direct-coupling mechanism to be brought in the slip direct-coupled state when it is determined that the internal combustion engine is running in at least one of the low rotation speed area and the decelerating area; (b) determining whether or not a variation in a rotational rate of an input and output shaft of the automatic transmission goes beyond a first permissible range when the direct-coupling mechanism is controlled to be brought in the slip direct-coupled state; (c) changing the direct-coupling mechanism from the slip direct-coupled state to the non-direct-coupled state when it is determined that the variation in the rotational rate of the input and output shaft of the automatic transmission goes beyond the first permissible range; (d) determining whether or not the variation in the rotational rate of the input and output shaft of the automatic transmission goes beyond a second permissible range after the change to the non-direct-coupled state is made; and (e) detecting generation of direct-coupling vibration attributable to the slip direct-coupled state when it is determined that the variation in the rotational rate of the input and output shaft of the automatic transmission goes beyond the second permissible range.