Honda Giken Kogyo Kabushiki Kaisha

Kouji Shibuya

Tatsuyuki Ohashi

Kazuo Okada

Osahide Miyamoto

Akio Tsuura

Shoichi Tanizawa

Takamichi Shimada

Toshiyuki Suzuki

Takashi Arai

Yoshinori Yamamoto

Norio Nakauchi

Satoru Sunada

Koichi Hasegawa

Shinichi Nishio

Hiroyuki Takeo

Masatoshi Shimizu

Takehiro Katakura

Hiromitsu Ishibashi

Hiroyuki Katano

Kazuhiro Nakajima

Hiroyuki Nakamura

Yoshiaki Shuto

Hironori Fujita

A control system for an automatic transmission of a vehicle is disclosed. The automatic transmission operates in a manual operating mode in which a shift position of the automatic transmission can be changed according to a shift instruction issued by a driver of the vehicle, or in an automatic operating mode in which the shift position is automatically selected. In the control system, a slow running intention of the driver is detected. A first shift position is set to a starting shift position at the time of starting the vehicle when the slow running intention of the driver is not detected in the manual operating mode. A second shift position which is lower in transmission gear ratio than the first shift position is set to the starting shift position when the slow running intention of the driver is detected in the manual operating mode.

Control system for an automatic transmission of a vehicle

At downshifting, hydraulic pressure of hydraulic clutch on engaging side (ON clutch pressure) is increased when an input and output speed ratio ('Gratio') has fallen below a predetermined value YGDNS. YGDNS is variably set depending on the vehicle speed and the engine temperature so that it becomes a lower value at a high vehicle speed than at a low vehicle speed, and a higher value at a low engine temperature than at a high temperature. When a downshifting command to a still lower speed stage is issued during downshifting control (when FTBD=1), a downshifting completion processing is performed in the course of the downshifting control (step in S111). Oil pressure in a hydraulic engaging element on the disengaging side QDNOFF and oil pressure in a hydraulic engaging element on the engaging side QDNON are switched to the oil pressures at the time of completion of downshifting, to thereby complete the first step downshifting control at an early time. In order to prevent unnecessary speed changing at the time of tire locking, downshifting is prohibited when deceleration of the vehicle speed has exceeded a predetermined value (when a setting of FLOCK=1 is made).

Control apparatus for hydraulically operated vehicular transmission

Upshifting is performed in a short time without giving rise to shocks. For that purpose, at the time of upshifting, a hydraulic pressure (QUPOFF) of a hydraulic engaging element on disengaging side is controlled such that the input and output speed ratio ('Gratio') of a transmission is decreased to, and held at, a predetermined slipping region (YG(N)S) that is lower than an engaging region (YG(N)L)-YG(N)H) to be set based on a gear ratio which is established by the engagement of the hydraulic engaging element on the disengaging side. The hydraulic pressure (QUPON) of a hydraulic engaging element on engaging side is gradually increased. When 'Gratio' once falls below YG(N)L and then increases up again to YGCONOK, QUPOFF is lowered to a predetermined low pressure (QUPOFFB) at a lapse of a predetermined time (YTMUP8). Once 'Gratio'&gt;YGCONOK, QUPON is increased to a predetermined high pressure QUPONB at a lapse of a second predetermined time YTMUP3. YTMUP8 is set so as to become shorter with an increase in a vehicle speed, and YTMUP3 is set so as to become longer with an increase in the vehicle speed.

Both shocks and time lag at the time of gear-in are reduced. For that purpose, the hydraulic pressure of a hydraulic engaging element to be engaged at the time of gear-in (in-gear pressure) QING is increased relatively rapidly at the beginning of gear-in. The speed of increase of QING is lowered after the input and output speed ratio 'Gratio' of a transmission has exceeded a predetermined value YINGS which works as a basis for discriminating the start of engagement of the hydraulic engaging element.

Control apparatus for vehicular automatic transmission

In a control apparatus for a hydraulically operated vehicular transmission having a plurality of speed stages to be established by a selecting operation of a plurality of hydraulic clutches, when a command to downshift to G(N-2) is issued in the course of downshifting to G(N-1) and a flag FTBD is set to 1, a control is performed to accelerate the time of completion of the downshifting control to G(N-1). When that oil temperature in the transmission which is detected by an oil temperature sensor is lower than a predetermined value, the setting of FTBD to 1 is prohibited. Therefore, at the time of low oil temperature, the downshifting to G(N-1) is performed in an ordinary manner. At the time of starting of the downshifting control from G(N-1) to G(N-2), the hydraulic pressure in the hydraulic clutch for the speed stage G(N-1) is sufficiently increased. A smooth downshifting to G(N-2) can thus be smoothly performed without the occurrence of excessive engine racing.

Manual speed changing is performed in a shorter time without giving rise to shocks. For that purpose, at the time of manual speed changing, a hydraulic pressure QUPON of a hydraulic engaging element on the engaging side is corrected by boosting. A correction value QUPONX before starting of an inertia phase and a correction value QUPONY after starting of the inertia phase are separately set. By making QUPONX&gt;QUPONY, the time required for manual speed changing as well as the shocks at the time of speed changing are reduced.

A facing surface of a clutch piston is previously moved to a position just before it abuts against an inner surface of a torque converter cover, or a position in which it extremely slightly abuts against the inner surface of the torque converter cover by outputting an initial engage pressure YMIN set in accordance with a vehicle speed and the like only for a predetermined time TMPS prior to the start of engagement of a lockup clutch. When the engagement of the lockup clutch is started, the engage pressure is gradually increased. When the engage pressure approaches a target pressure set in accordance with the target speed ratio, a feedback control of the engage pressure is carried out such that the actual speed ratio of the torque converter is converged to the target speed ratio. Thus, when the lockup clutch of the torque converter is brought into an engaged state, the responsiveness can be enhanced while preventing the generation of a shock.

Control device for lockup clutch

Growing community of inventors

Saitama-ken, Japan

Kouji Shibuya