Method and system for controlling automatic transmission

A system for controlling an automatic transmission comprising:

• an output shaft rotation speed sensor condition judging device judging whether an output shaft rotation speed sensor for detecting a rotation speed of an output shaft of the automatic transmission is in a normal or a faulty state;
• an input shaft rotation speed sensor condition judging device judging whether an input shaft rotation speed sensor for detecting a rotation speed of an input shaft of the automatic transmission is in a normal or a faulty state;
• multiplying means for multiplying the rotation speed of said output shaft detected by said output shaft rotation speed sensor and a currently selected gear ratio of the automatic transmission;
• and
• comparing and judging means for comparing and judging whether a product value of the rotation speed of said output shaft detected by said output rotation speed sensor and the currently selected gear ration of the automatic transmission matches with the rotation speed of the input shaft;
• wherein said output shaft rotation speed sensor condition judging device judging a condition of said output shaft rotation speed sensor judges that said output shaft rotation speed sensor is in normal state on the basis of a judgment that the product value of the rotation speed of said output shaft detected by said output shaft rotation speed sensor and the gear ratio of the currently selected gear of the automatic transmission equals the rotation speed of the input shaft as checked by the comparing and judging means, and
• wherein the judgment that the output shaft rotation speed sensor is in normal state can be made only when the rotation speed of the input shaft detected by said input shaft rotation speed sensor falls within a predetermined range in said step of judging a state of said output shaft rotation speed sensor.

A method for controlling an automatic transmission comprising the steps of:

• judging whether an input shaft rotation speed sensor for detecting a rotation speed of an input shaft of the automatic transmission is in a normal state or a faulty state;
• judging whether an output shaft rotation speed sensor for detecting rotation speed of an output shaft of the automatic transmission is in a normal state or a faulty state;
• switching a control mode for the automatic transmission from a normal mode, in which a transmission gear ratio is determined depending upon predetermined shifting parameters, to a fail-safe mode, in which a transmission gear ratio is fixed at a predetermined transmission gear ratio, in response to detection of a faulty state in at least one of said input shaft rotation speed sensor and said output shaft rotation speed sensor;
• checking whether a predetermined normal mode control resuming condition is satisfied which includes at least establishing a power train for transmitting a drive torque for a final drive, responsive to termination of the faulty state of said at least one of said input shaft rotation speed sensor and said output shaft rotation speed sensor, while the control mode for the automatic transmission is maintained in said fail-safe mode, and generating a normal mode resuming demand when said predetermined normal mode control resuming condition is satisfied;
• and
• resuming the normal mode of control for said automatic transmission in response to said normal mode resuming demand.

A system for controlling an automatic transmission comprising:

• input shaft rotation sensor condition judging means for judging whether an input shaft rotation speed sensor for detecting a rotation speed of an input shaft of the automatic transmission is in a normal state or a faulty state;
• output shaft rotation speed sensor condition judging means for judging whether an output shaft rotation speed sensor for detecting rotation speed of an output shaft of the automatic transmission is in a normal state or a faulty state;
• control mode switching means for switching a control mode for the automatic transmission from a normal mode, in which a transmission gear ratio is determined depending upon predetermined shifting parameters, to a fail-safe mode, in which a transmission gear ratio is fixed at a predetermined transmission gear ratio, in response to a detection of a faulty state in at least one of said input shaft rotation speed sensor and said output shaft rotation speed sensor;
• and
• normal mode resuming condition detection means for checking whether a predetermined normal mode control resuming condition is satisfied, which includes at least establishing a power train for transmitting a drive torque for a final drive responsive to termination of the faulty state of said at least one of said input shaft rotation speed sensor and said output shaft rotations speed sensor, while the control mode for the automatic transmission is maintained in said fail-safe mode, and generating a normal mode resuming demand when said predetermined normal mode control resuming condition is satisfied,
• wherein said control mode switching means resumes the normal mode of control for said automatic transmission in response to said normal mode resuming demand.

A method for controlling an automatic transmission comprising the steps of:

• judging whether an output shaft rotation speed sensor for detecting a rotation speed of an output shaft of the automatic transmission is in a normal state or a faulty state;
• judging whether an input shaft rotation speed sensor for detecting a rotation speed of an input shaft of the automatic transmission is in a normal state or a faulty state;
• multiplying the rotation speed of said output shaft rotation speed sensor and a gear ratio of a currently selected gear of the automatic transmission;
• and
• comparing and judging whether a product value of the rotation speed of said output shaft detected by said output shaft rotation speed sensor and the gear ratio of the currently selected gear of the automatic transmission matches with the rotation speed of the input shaft;
• and
• wherein in said step of judging a condition of said input shaft rotation speed sensor, an input shaft rotation speed sensor condition judging device judges that said input shaft rotation speed sensor is in a normal state on the basis that the product value of the rotation speed of said output shaft detected by said output shaft rotation speed sensor and the gear ratio of the currently selected gear of the automatic transmission is equal to the rotation speed of the input shaft as checked at the comparing and judging step, and said step of judging the condition of said input shaft rotation speed sensor judges that said input shaft rotation speed sensor is in a faulty state when the rotation speed of said input shaft rotation speed sensor is lower than a predetermined input shaft rotation speed while a rotation speed of an engine speed sensor is at least a predetermined engine rotation speed and the rotation speed of the output shaft rotation speed sensor is at least a predetermined output shaft rotation speed.

A system for controlling an automatic transmission comprising:

• input shaft rotation speed sensor condition judging means for judging whether an input rotation shaft speed sensor for detecting a rotation speed of an input shaft of the automatic transmission is in a normal state or a faulty state;
• output rotation speed sensor condition judging means for judging whether an output shaft rotation speed sensor for detecting a rotation speed of an output shaft of the automatic transmission is in a normal state or a faulty state;
• multiplying means for multiplying the rotation speed of said output shaft detected by said output shaft rotation speed sensor and a gear ratio of a currently selected gear of the automatic transmission;
• and
• comparing and judging means for comparing and judging whether a product value of the rotation speed of said output shaft detected by said output shaft rotation speed sensor and the gear ratio of the currently selected gear of the automatic transmission matches with the rotation speed of the input shaft;
• wherein said input shaft rotation speed sensor condition judging means judging a condition of said input shaft rotation speed sensor judges that said input shaft rotation speed sensor is in normal state on the basis of judgment that the product value of the rotation speed of said output shaft detected by said output shaft rotation speed sensor and the gear ratio of the currently selected gear of the automatic transmission is equal to the rotation speed of the input shaft as checked by the comparing and judging means, and judges that said input shaft rotation speed sensor is in a faulty state when the rotation speed of said input shaft rotation speed sensor is lower than a predetermined input shaft rotation speed while a rotation speed of an engine speed sensor is at least a predetermined engine rotation speed and the rotation speed of said output shaft rotation speed sensor is at least a predetermined output shaft rotation speed.