Nissan Motor Company Limited

Yasushi Narita

Tatsuya Nagato

Masato Koga

Satoshi Takizawa

Hiromasa Sakai

Yuusuke Minagawa

Motoharu Nishio

Itsuro Muramoto

Yoshinori Iwasaki

Hiroaki Kuramoto

Hiroshi Takahashi

Kazuhiro Yamada

Masaki Nakano

Makoto Kimura

Hiroyuki Hirano

Toshimi Abo

Shusaku Katakura

Yasuhiro Niikura

Taketoshi Kawabe

Yusuke Minagawa

Hirofumi Shimizu

Noboru Hattori

Hitoshi Kidokoro

Kazuhiro Takeda

Eio Sagara

Masayoshi Kimura

Shin-ichiro Joe

Manzaburou Abe

Hisaaki Tohjima

A controller calculates a target speed ratio of a continuously variable transmission incorporated into an infinitely variable transmission for a vehicle and a target vehicle speed according to a vehicle running state. When a predetermined creep torque limiting condition holds, the controller limits the target vehicle speed such that the difference between the target vehicle speed and the real vehicle speed is within a predetermined range. By controlling the speed ratio of the continuously variable transmission such that this difference diminishes, the infinitely variable transmission generates a creep torque consistent with the intention of the driver.

Control of infinitely variable transmission

A controller ( ) calculates a target speed ratio of a continuously variable transmission ( ) incorporated into an infinitely variable transmission for a vehicle and a target vehicle acceleration based on a vehicle running state. When a predetermined creep torque control condition holds (S -S S ), the controller ( ) corrects the target speed ratio such that the deviation of the target acceleration from the real vehicle acceleration to decrease. By controlling the speed ratio of the continuously variable transmission to the corrected target speed ratio, the infinitely variable transmission generates a creep torque consistent with the driver's intention.

An infinite Speed ratio continuously variable transmission comprises a power recirculation mode clutch ( ) and direct mode clutch ( ). At least one of the power recirculation mode clutch ( ) and direct mode clutch ( ) comprises an electromagnetic two-way clutch. The electromagnetic two-way clutch maintains the engaged state during excitation and can transmit drive force from both the drive side and non-drive side. On the other hand, when there is a change-over from the energized state to the non-energized state, a one-way clutch state is obtained wherein drive force is permitted only in the transmission direction of drive force in the instant of the change-over to non-excitation. When a drive force is input in the reverse direction to the drive force transmitted in the one-way clutch state, the one-way clutch state is disengaged, and the disengaged state of the clutch is maintained until subsequent re-excitation. Therefore, change-over of the clutch at the rotation synchronous point RSP where the power recirculation mode and direct mode are changed over, can be performed rapidly.

Infinite speed ratio continuously variable transmission

An infinite speed ratio continuously variable transmission is provided with a continuously variable transmission ( ), fixed speed ratio transmission ( ), planetary gear set ( ), power recirculation clutch ( ) and direct clutch ( ). A target speed ratio of the infinite speed ratio continuously variable transmission is set based on a vehicle speed and an accelerator pedal depression amount. When the target speed ratio varies beyond a rotation synchronous point, a control unit ( ) assigns an order of priority to control of the power recirculation clutch ( ) and direct clutch ( ), and control of the speed ratio of the continuously variable transmission ( ), and thereby causes a real speed ratio of the infinite speed ratio continuously variable transmission to vary in the same direction until it reaches the target speed ratio (S , S , S , S , S , S ).

Speed change controller and control method of infinite speed ratio continuously variable transmission

In an infinite speed ratio transmission comprising a continuously variable transmission (,), reduction gear unit (,) and planetary gear set (,), the speed ratio of the continuously variable transmission (,) is controlled by a step motor (,). A range selected by a selector lever (,) is detected by a sensor (,). When the selected range has changed from a stationary range to one of a forward motion range and a reverse motion range, a microprocessor (,) first drives the step motor (,) to a predetermined position (S,, S,). Subsequently, by driving the step motor (,) to an operating position corresponding to a geared neutral point at which the output rotation speed of the infinite speed ratio transmission is zero (S,, S,, S,, S,, S,, S,), the undesirable effects of hysteresis occurring in a relation between the operating position of the step motor (,) and the speed ratio of the continuously variable transmission (,) according to a torque shift of the continuously variable transmission (,) are avoided.

Controller for infinite speed ratio transmission

In a toroidal continuously variable transmission for a vehicle, either of an automatic operation mode and a manual operation mode is selected by a driver via a selector lever (,). A speed ratio grade in the manual operation mode is also designated via the selector lever (,) by the driver. A controller (,) is programmed to control a speed ratio of the transmission to a target speed ratio corresponding to the designated speed ratio grade. The controller (,) is further programmed to prevent the speed ratio from varying after an input torque to the transmission has changed. This control may be realized by setting different target speed ratios for an identical speed ratio grade according to the input torque of the transmission.

Speed ratio controller and control method of toroidal continuously variable transmission

A first final target input rotation speed is calculated according to a throttle opening and a vehicle speed, and a second final target input rotation speed is calculated by applying an upper limit to the first final target input rotation speed. The upper limit is determined so as to reduce noise outside the vehicle. A second final target speed ratio is set from the vehicle speed and second final target input rotation speed, and a time constant of a speed ratio variation is determined from the vehicle speed and first final target input rotation speed. By transiently controlling the speed ratio variation using the second final target speed ratio and time constant thus obtained, an excessive increase of engine rotation speed is prevented while retaining a desirable feeling of acceleration when there is a kickdown operation of the vehicle.

Speed controller and control methods of continuously variable transmission

A controller (61) calculates a transient target speed ratio based on a final speed ratio set according to a vehicle running condition and second order delay time constant gains (75, S99), and control a speed ratio of a continuously variable transmission to the transient target speed ratio via an actuator (4) (87, S103). The controller (61) also calculates the deviation between the final target speed ratio and transient target speed ratio (74, S95), and determines the second order delay time constant gains based on the deviation (74, S98). Preferably, the gains are determined so that the response rate is slower the larger the deviation (74, S134, S135, S136, S137, S139, S140, S141).

Speed ratio control device and control method for automatic transmission

A gyration angle .phi. of a power roller (3) of a toroidal continuously variable transmission (10) is made to vary via a step motor (4) and control valve (5). A controller (61) calculates a feedback control amount v of a step motor (4) so that a real speed ratio i of the transmission (10) coincides with a target speed ratio i*. The controller (61) calculates a command value u by correcting a control value v based on a non-linear relation between the gyration angle .phi. and the real speed ratio i, and controls the actuator (4) based on the command value u.

Speed ratio controller and control method of continuously variable

A lock-up control apparatus for a vehicle automatic transmission enables an engine stalling prevention at the time of a sudden deceleration in the lock-up state of a torque converter without causing the slip of the torque converter before the sudden deceleration, and prevents effectiveness of the fuel consumption from being sacrificed by a fuel cut. A controller performs the change-speed control on an automatic transmission through shift solenoids and on the basis of a throttle opening and a transmission output speed, and also performs the lock-up control of the torque converter through a lock-up solenoid. During the coasting drive when the throttle opening is set close to zero, the controller sets the torque converter to have a minimum lock-up capacity through the lock-up solenoid within such a range that no slip occurs. When the sudden deceleration is carried out, the controller releases the lock-up, though this lock-up release is rapidly achieved with the minimum lock-up capacity thereby to avoid the engine stalling.

Lock-up control apparatus for automatic transmission

There is proposed a practical approach to a shift, in an automatic transmission, in which a release element is released and an apply element is engaged. The release element is released or vented at an appropriate timing after development of torque by the apply element but before initiation of inertia phase. Specifically, the release element is released when transmission output torque (To) reaches a value (Toh) calculated out of gear ratio after shift (grmin), transmission input (or turbine) torque (Tt) and transmission input (turbine) acceleration (NTd). If desired, without relying on measurement of output torque (To), the release element may be released when transmission output acceleration (No), namely, vehicle acceleration, reaches a value which may be fixed or accelerator position dependent.

Control for shift in automatic transmission

An adaptive correction of an inappropriate shift operation is disclosed. During a power-off upshift, a variation in output torque of the transmission output shaft is detected. A decision is made based on this output torque variation whether or not the power-off 1-2 upshift has been effected in a predetermined appropriate manner, and a timing at which an on-coming friction device to be engaged during the power-off upshift is corrected based on the decision made. Thus, the shift operation during the next occurrence of a power-off upshift of the same type is effected in the appropriate manner.

Adaptive correction of inappropriate shift in automatic transmission

A shift control system detects a traveling resistance as a factor influencing the vehicular driving performance. The shift control system varies preset shift pattern according to the detected traveling resistance of the vehicle for optimizing selection of the shift pattern. The shift control system thus controls the speed ratio of an automatic power transmission depending upon the control parameters, such as an engine load and a vehicle acceleration.

Shifting control system for automotive automatic power transmission with

A shift control strategy is disclosed whereby a timing at which the states of shift solenoids are switched is determined based on an actual revolution speed ratio, namely a ratio of revoltion speed of an input shaft of a gear train to a revolution speed of an output shaft thereof, and a predetermined data containing various revolution speed ratio values versus kinds of shift and throttle opening degrees.

Shift control system for automatic transmission

A line pressure control during a shifting operation of an automatic transmission is disclosed. Quality of each shifting operation is represented by a predetermined variable, viz, an inertia phase time during which a gear ratio undergoes a variation. When a deviation between circumstances detected upon occurrence of a shifting operation and predetermined circumstances under which a target value is set fails to fall in a predetermined range, a deviation indicative signal is generated. Upon absence of this deviation indicative signal after completion of the shifting operation, the inertia phase time measured during the shifting operation is compared with the target value and the line pressure is adjusted in response to this comparison result when the shifting operation of the same kind is to occur under substantially the same circumstances detected. In other words, the learning to adjust the line pressure is prohibited when the deviation indicative signal is present.

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Yokohama, Japan

Yasushi Narita