Nissan Motor Company Limited

Jatco Corporation

Junya Takayama

Hiroyasu Tanaka

Masato Koga

Shigeki Shimanaka

Satoshi Takizawa

Masatoshi Akanuma

Takayuki Suzuki

Tateki Jozaki

Yasutaka Kawamura

Takashi Hara

A starting shift control system for a continuously variable transmission is provided which includes a control unit having a high start judgment device for judging whether or not a high start in a high speed side gear ratio is caused on the basis of a comparison between the generated number of the input rotation pulses and the generated number of the output rotation pulses from the time a first vehicle starting operation is performed after start of a prime mover, and a high start control device for restricting downshifting from the high speed side gear ratio to a target gear ratio when a start of the vehicle is judged to be the high start. A starting shift control method is also provided.

Starting shift control system and method for continuously variable transmission

After an engine ( ) has started, a controller ( ) starts determining whether lockup should be prohibited or permitted based on the cooling water temperature of an engine ( ) or the oil temperature of a transmission ( ). Once it has been determined that lockup should be permitted, the controller ( ) stops determining whether lockup should be prohibited or permitted until the next time the engine ( ) is started. In this way, once the conditions for determining that lockup should be permitted hold, lockup prohibition or permission based on the engine cooling water temperature or transmission oil temperature is no longer determined, so repeat engaging and disengaging of the lockup clutch ( ) due to fluctuations of engine cooling water temperature or transmission oil temperature, is prevented.

Lockup control device for transmission

The vehicle comprises a continuously variable transmission and traction control system (TCS) which controls a driving force. When the TCS is not operating, a controller computes a final target ratio based on a sensor detected vehicle speed. When the TCS is operating, the final target ratio is computed based on an estimated vehicle speed, and the final target ratio is limited by a speed ratio upper limiting value computed based on the sensor detected vehicle speed. The controller controls a speed change actuator so that a real speed ratio approaches the final target ratio.

Speed ratio control device for vehicle

An alarm is emitted when a vehicle attempts to start when the speed ratio of a toroidal continuously variable transmission is small. A sensor ( ) detects that the speed ratio is smaller than a predetermined range. A microprocessor ( ) controls an alarm ( ) to operate when an ignition switch ( ) is in a position for starting an engine, while the speed ratio is smaller than the predetermined range.

Small speed ratio detection and control devices for vehicle start

A first switch ( ) which can select a manual mode, and a second switch ( ) which can select one of an upshift and a downshift, are provided. A microprocessor ( ) varies a speed ratio of an automatic transmission ( ) according to the specification of the second switch ( ) when the first switch ( ) has previously selected the manual mode, and the second switch ( ) subsequently specifies one of the upshift and the downshift (S , S , S , S , S , S , S , S , S , S , S ). On the other hand, variation of the speed ratio of the automatic transmission ( ) according to the specification of the second switch ( ) is prohibited when the second switch ( ) specifies one of the upshift and the downshift at a timing not later than a timing at which the manual mode is selected by the first switch ( ) (S , S , S , S , S , S , S , S , S , S , S ). Due to this processing, an unexpected speed ratio variation is prevented from occurring simultaneously when the first switch ( ) selects the manual mode in the state where the second switch ( ) has been fixed in the ON state due to malfunction or misoperation of the second switch ( ).

Manual operation control of automatic transmission

A speed change control device for an automatic transmission wherein the speed ratio is automatically varied according to a running state when an automatic shift mode is selected, and the speed ratio is varied based on a manual operation when the manual shift mode is selected. When there is a change-over from the automatic shift mode to the manual shift mode, a speed ratio immediately after the change-over is set to a speed ratio such that a transmission input rotation speed after the change-over increases by at least a predetermined rotation speed compared to the transmission input rotation speed before the change-over. In this way, the effectiveness of engine braking is enhanced immediately after a change-over to the manual shift mode, or a downshift for acceleration can be definitively performed.

Speed ratio control device

When a slip control system starts operating, a vehicle speed VSP used for speed change control is simultaneously changed over from a sensor detected vehicle speed VSPSEN to an estimated vehicle speed VSPFL. On the other hand, when the slip control system has stopped, it is first determined whether a speed ratio variation amount, due to the change-over of the vehicle speed used for speed change control from the estimated vehicle speed VSPFL to the sensor detected vehicle speed VSPSEN, is less than a permissible amount. When it is determined that the speed ratio variation amount is smaller than the permissible amount, the vehicle speed used for speed change control is changed over from the estimated vehicle speed VSPFL to the sensor detected vehicle speed VSPSEN. By performing this change-over, a sharp variation of the vehicle speed used for speed change control is suppressed, and a sharp variation of the speed ratio leading to shocks or slipping is suppressed.

A controller determines whether or not the vehicle dynamics controller is operating, and when it is determined that it is operating, a speed change operation by an actuator which changes over a gear position of the automatic transmission is prohibited. This speed change prohibition is continued for a predetermined time even when the vehicle dynamics controller has stopped. In this way, control performance of the vehicle dynamics controller is prevented from becoming unstable due to a speed change of the automatic transmission.

A lock-up torque converter is equipped with a lock-up clutch. The lockup clutch may engage even when the vehicle is coasting (lock-up coasting). When an accelerator pedal is depressed in a stepwise manner during lock-up coasting, the lock-up clutch is temporarily disengaged. By setting the threshold value used for determination so that it is easier to determine that the accelerator pedal was depressed in a stepwise manner the lower the vehicle speed, the dual objectives of vibration suppression of the drive system and improvement of fuel cost-performance are realized.

Lock-up control device for vehicle

When a slip control system is not operating, a speed ratio control device uses a sensor detected vehicle speed for speed ratio control, and when the slip control system is operating, it uses an estimated vehicle speed for speed ratio control. It is determined whether a variation amount of the estimated vehicle speed is greater than a threshold set to a variation amount which could not be obtained when there is no error. When the variation amount of the estimated vehicle speed is greater than the threshold, it is determined that the estimated vehicle speed is abnormal, and use of the estimated vehicle speed for speed ratio control is prohibited.

Growing community of inventors

Oomiya, Japan

Junya Takayama