Control apparatus of automatic transmission

1. A control apparatus for a vehicle, comprising:

an automatic transmission configured to attain a predetermined shift-stage by releasing an engaged friction-engagement element and by engaging a released friction-engagement element;

a variation-start detecting section configured to detect that a parameter which varies with a progress of an inertia phase has started to vary in accordance with a variation rate of a turbine rotational speed;

a memorizing section configured to sequentially memorize a slip amount until the variation-start detecting section detects that the parameter has started to vary; and

a learning section configured to:

correct a control quantity for a next-time shift of the automatic transmission, based on the slip amount memorized at a start timing of the inertia phase, and

recognize the start timing of the inertia phase as being at a time that is earlier by a given time interval than a time when the variation-start detecting section detects that the parameter has started to vary.

2. The control apparatus as claimed in claim 1 , wherein

the control apparatus further comprises a variation-rate detecting section configured to detect a variation rate of the parameter varying with the progress of the inertia phase, and

the learning section is configured to set the given time interval to become shorter as an absolute value of the variation rate of the parameter becomes larger.

3. The control apparatus as claimed in claim 1 , wherein the control apparatus further comprises:

a lockup clutch provided in a torque converter interposed between the automatic transmission and a drive source of the vehicle, the lockup clutch being configured to engage input and output elements of the torque converter with each other;

a lockup-clutch control section configured to control a hydraulic pressure of the lockup clutch; and

an initial-pressure control section configured to control the hydraulic pressure of the lockup clutch to be a predetermined initial pressure when a shift of the automatic transmission is started,

wherein the slip amount that the memorizing section is configured to sequentially memorize is a slip amount of the lockup clutch that is memorized until the variation-start detecting section detects that the parameter has started to vary, and

wherein the learning section is configured to correct the predetermined initial pressure for the next-time shift such that the slip amount of the lockup clutch memorized at the time that is earlier by the given time interval than the time when the variation-start detecting section detected that the parameter had started to vary is brought close to a predetermined target initial slip amount.

4. The control apparatus as claimed in claim 3 , wherein

the control apparatus further comprises a variation-end detecting section configured to detect that the variation of the parameter has almost ended,

the learning section is configured to correct the control quantity for the next-time shift such that the slip amount of the lockup clutch memorized at the time that is earlier by the given time interval than the time when the variation-start detecting section detected that the parameter had started to vary is brought close to the predetermined target initial slip amount, and such that the slip amount of the lockup clutch memorized at a time later by a second given time interval than a time when the variation-end detecting section detected that the variation of the parameter had almost ended is brought close to a predetermined target latter slip amount.

5. The control apparatus as claimed in claim 3 , wherein the control apparatus further comprises a prohibiting section configured to prohibit the learning section from correcting the predetermined initial pressure when a variation amount of driving force of the drive source during the shift is larger than or equal to a predetermined amount.

6. A control apparatus for a vehicle, comprising:

an automatic transmission configured to attain a predetermined shift-stage by releasing an engaged friction-engagement element and by engaging a released friction-engagement element;

variation-start detecting means for detecting that a parameter which varies with a progress of an inertia phase has started to vary in accordance with a variation rate of a turbine rotational speed;

memorizing means for sequentially memorizing a slip amount until the variation-start detecting means detects that the parameter has started to vary; and

learning means for correcting a control quantity for a next-time shift of the automatic transmission, based on the slip amount memorized at a start timing of the inertia phase, and

means for recognizing the start timing of the inertia phase as being at a time that is earlier by a given time interval than a time when the variation-start detecting means detects that the parameter has started to vary.

7. A control method for a vehicle including a controller and an automatic transmission configured to attain a predetermined shift-stage by releasing an engaged friction-engagement element and by engaging a released friction-engagement element, the control method comprising:

detecting that a parameter which varies with a progress of an inertia phase has started to vary in accordance with a variation rate of a turbine rotational speed;

sequentially memorizing a slip amount until detection is made that the parameter has started to vary;

recognizing a start timing of the inertia phase as being at a time that is earlier by a given time interval than a time when it is detected that the parameter has started to vary; and

correcting, by the controller, a control quantity for a next-time shift of the automatic transmission, based on the slip amount memorized at the start timing of the inertia phase.