Jatco Corporation

Nissan Motor Company Limited

Toshiaki Noda

Keichi Tatewaki

Takahiro Yamada

Katsuhiko Okada

Kunihiro Takahashi

Yuji Okamoto

Takashi Koguchi

Syunsuke Iwamoto

Hiroyasu Tanaka

Hideshi Wakayama

Takuichiro Inoue

Makoto Komatsu

Sho Okutani

Yuuji Nagase

Takehiro Iizumi

Yuichi Ishiyama

A control device for a lock-up clutch includes a control unit, an abnormality determination unit, a release control unit and a prohibition unit. The control unit is configured to control an engagement state of a lock-up clutch, and to perform a slip lock-up control by performing a feedback control of an engagement hydraulic pressure to be a first slip amount during coasting. The abnormality determination unit is configured to determine an abnormality when a state continues with a slip amount being equal to or greater than a second slip amount. The release control unit is configured to release the lock-up clutch when the abnormality is determined. The prohibition unit is configured to allow the control unit to raise the engagement hydraulic pressure by a prescribed pressure, and to prohibit determination by the abnormality determination unit, when the transmission ratio is downshifted during coasting while the slip lock-up control is performed.

Control device and control method for lock-up clutch

A lockup control device for a vehicle includes: a torque converter, and a lockup control configured to increase a lockup pressure difference command to an initial pressure difference, when a turbine rotation speed variation amount of the torque converter becomes smaller than a predetermined value during a ramp control in which the lockup pressure difference command is increased by a ramp pressure difference, the lockup control section being configured to switch to a second increase gradient having an increase gradient lower than a first increase gradient of the ramp pressure difference when the turbine rotation speed variation amount is equal to or greater than the predetermined value.

Lock-up control device for a vehicle

A lockup control device for a vehicle includes: a torque converter; a lockup control section configured to increase a lockup pressure difference command to an initial pressure difference when a lockup engagement condition is satisfied in a disengagement state of the lockup clutch, and then to increase the lockup pressure difference command by a ramp pressure difference by a predetermined gradient, the lockup control section being configured to determine a ramp start condition by which the lockup pressure difference command is switched from the initial pressure difference to the ramp pressure difference, based on a speed ratio which is a ratio of input and output rotation speeds of the torque converter.

Lock-up control device for vehicle

An automatic transmission control device implements a downshift by disengagement of a clutch that is engaged in a gear position before the downshift. It is determined whether an engine state is in a predetermined region in which a change of an engine torque per a change of an accelerator pedal opening is smaller than that in another region, and the engine torque is within a predetermined range, and an engine rotational speed is within a predetermined range. It is determined whether an operating state is in a predetermined state of accelerator operation in which the accelerator pedal opening is larger than a predetermined value, and an accelerator pedal opening change rate has an absolute value smaller than a predetermined value. The downshift is inhibited in response to determination that the engine state is in the predetermined region and the operating state is in the predetermined state of accelerator operation.

Automatic transmission control device

A torque converter defines an ellipticity lower than or equal to 0.23 which is an outermost length of the torque converter in an axial direction, divided by an outermost diameter of the torque converter in a radial direction. The torque converter includes: a pump impeller connecting to an input shaft; a turbine runner opposed to the pump impeller and connecting to an output shaft; and a stator disposed between an inlet of the pump impeller and an outlet of the turbine runner, by way of a one way clutch which allows a one way rotation. The torque converter transmits a power by circulating a fluid through the pump impeller, the turbine runner and the stator. A first area ratio A is: 0.23&#x2266;A&#x2266;0.45, A second area ratio B is: 0.23&#x2266;B&#x2266;0.45, and A third area ratio C is: 0.15&#x2266;C&#x3c;0.23.

Torque converter

In a torque converter comprised of three major rotating elements, namely a pump impeller formed integral with a converter cover, a turbine runner to which a driving power is transmitted through a working fluid from the pump impeller, and a stator disposed between the pump impeller and the turbine runner, the stator is supported on a transmission case via a one-way clutch and has a plurality of stator blades. In order to balance the enhanced vehicle's startability and improved fuel economy at idle, the ratio W/D of a stator-blade axial length W to a torque-converter nominal diameter D is set to satisfy a predetermined inequality 0.030&#x2266;W/D&#x2266;0.052.

In a torque converter comprised of three major rotating elements, namely a pump impeller, a turbine runner to which a driving power is transmitted through a working fluid from the pump impeller, and a stator disposed between the pump impeller and the turbine runner, a flattening ratio L/D of a sum L of an pump-impeller axial length and a turbine-runner axial length to a torque-converter nominal diameter D is set to be less than or equal to 0.21. In order to balance contradictory requirements, namely reduced curvature loss, i.e., enhanced converter efficiency, proper rate-of-change in working-fluid flow passage area, and proper breakaway of working fluid from each turbine blade, a ratio r/R of a radius of curvature r of a turbine-core outer peripheral curved surface to a radius of curvature R of a turbine-shell outer peripheral curved surface being set to satisfy a predetermined inequality 0.3&lE;r/R&lE;0.5.

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Kanagawa, Japan

Toshiaki Noda