초록 ▼

An automatic transmission includes a torque converter with a directly coupled clutch. A plurality of rotational speed sensors are used in the control of a lockup and a shifting operation. The invention provides an arrangement to detect any abnormality associated with such sensors. Under the lockup c

An automatic transmission includes a torque converter with a directly coupled clutch. A plurality of rotational speed sensors are used in the control of a lockup and a shifting operation. The invention provides an arrangement to detect any abnormality associated with such sensors. Under the lockup condition of the torque converter, a speed Ve detected by an engine rotational speed sensor, and speeds Vsp1 and Vsp2 detected by a first and a second vehicle speed sensor and a speed ratio K1 of a change gearing are used to detect any abnormality associated with the three sensors. All of the sensors are determined to be properly functioning when the equalities Ve=K1ㆍVsp1 and Ve=K1ㆍVsp2 apply. The first vehicle speed sensor is determined to be faulty when the former equation applies while the latter equation does not apply, and the second vehicle speed sensor is determined to be faulty when the former equality applies while the latter does not apply. When the both equalities do not hold, the engine rotational speed sensor is determined to be faulty.

대표청구항 ▼

A lockup control system for an automatic transmission including a torque converter having its input shaft coupled to an output shaft of an onboard engine, a directly coupled clutch providing a direct connection between the input and the output of the torque converter, a change gearing, and lockup ac

A lockup control system for an automatic transmission including a torque converter having its input shaft coupled to an output shaft of an onboard engine, a directly coupled clutch providing a direct connection between the input and the output of the torque converter, a change gearing, and lockup activate means for turning the directly coupled clutch on and off; the lockup control system comprising first and second detecting means for detecting the rotational speed of the output shaft of the change gearing; third detecting means for detecting the rotational speed of the output shaft of the engine; an electronic controller operative under the lockup condition of the torque converter to compare the rotational speed detected by the first detecting means and the rotational speed detected by the third detecting means, as weighted according to a particular speed range in which the change gearing operates, against each other, thereby determining any abnormality in the relative detection by the first and the third detecting means; said electronic controller operative under the lockup condition of the torque converter to compare the rotational speed detected by the second detecting means and the rotational speed detected by the third detecting means, as weighted according to a particular speed range in which the change gearing operates, against each other, thereby determining any abnormality in the relative detection by the second and the third detecting means; said electronic controller designating the speed detected by the first detecting means as the vehicle speed when it fails to determine both of the abnormalities in the relative detection by the first and the third detecting means and by the second and the third detecting means and for designating the speed detected by the second detecting means as the vehicle speed when the abnormality in the relative detection by the first and the third detecting means is determined, while the abnormality in the relative detection by the second and the third detecting means is failed to determine; means for generating a signal representing an opening of a throttle valve of the engine; first storage means for storing reference information which is to be referred to in determining the activation of the lockup in a manner corresponding to the opening of the throttle valve; said electronic controller reading the reference information which corresponds to the opening of the throttle valve; said electronic controller responsive to the designated vehicle speed and the reference information which is read out to determine the need for the lockup and for providing a lockup command to the lockup activate means when it is determined that there is a need for the lockup; second storage means for storing lockup terminate reference information; said electronic controller reading the lockup terminate reference information; and said electronic controller responsive to the designated vehicle speed and the lockup terminate reference information which is read out to determine the need for the termination of the lockup and for providing a lockup terminate command to the lockup activate means when it is determined that there is a need to terminate the lockup.