Control system for automatic transmission

1. A control system for an automatic transmission in which a downshift is made by disengaging a disengaging-side engaging element and engaging an engaging-side engaging element, the control system comprising:

an engine control section configured to control an engine speed of an engine connected to the automatic transmission;

a downshift control section configured to provide a first engaging capacity to the disengaging-side engaging element and put the engaging-side engaging element in a disengaging state, to control the engine control section to maintain the engine speed at a level according to a gear of the automatic transmission to be obtained after the downshift, and to increase an engaging capacity of the engaging-side engaging element to engage the engaging-side engaging element and decrease the first engaging capacity of the disengaging-side engaging element to disengage the disengaging-side engaging element when a parameter representing a progressing condition of the downshift reaches a value, thereby carrying out the downshift in a power-on condition; and

a detecting section configured to detect an operating amount of an accelerator pedal,

wherein, when a power-off condition is detected upon the accelerator pedal being returned to a position representing an operating amount during the downshift, the downshift control section is configured to decrease the first engaging capacity of the disengaging-side engaging element to a second engaging capacity smaller than the first engaging capacity of the disengaging-side engaging element to continue the downshift which is currently progressing and to cause the engine control section to continue controlling the engine speed.

2. A control system as claimed in claim 1 , wherein the second engaging capacity is smaller as the downshift progresses at a time when the power-off condition is detected.

3. A control system for an automatic transmission in which a downshift is made by disengaging a disengaging-side engaging element and engaging an engaging-side engaging element, the control system comprising:

an engine control unit configured to control an engine speed of an engine connected to the automatic transmission;

a detector configured to detect an operating amount of an accelerator pedal; and

a downshift control unit configured to:

provide output representing a first engaging capacity being provided to the disengaging-side engaging element and the engaging-side engaging element being put in a disengaging state,

provide output representing the engine control unit to maintain the engine speed at a level according to a gear of the automatic transmission to be obtained after the downshift,

provide output representing an engaging capacity of the engaging-side engaging element to increase to engage the engaging-side engaging element and the first engaging capacity of the disengaging-side engaging element to decrease to disengage the disengaging-side engaging element when a parameter representing a progressing condition of the downshift reaches a value, thereby carrying out the downshift in a power-on condition, and

provide, when a power-off condition is detected upon the accelerator pedal being returned to a position representing an operating amount during the downshift, output representing the first engaging capacity of the disengaging-side engaging element to decrease to a second engaging capacity smaller than the first engaging capacity of the disengaging-side engaging element so as to continue the downshift which is currently progressing and the engine control unit to continue controlling the engine speed.

4. A control system as claimed in claim 3 , wherein the second engaging capacity is smaller as the downshift progresses at a time when the power-off condition is detected.