Mazda Motor Corporation

Manabu Sasahara

Tadashi Saito

Yutaro Fukuda

Tomohiro Kubo

Yuki Tsuchitori

Tatsuhiko Iwasaki

Tomotaka Ishizaka

Koshiro Saji

Shinya Kamada

Tatsutoshi Mizobe

Norio Iwashita

Kaori Sako

Shigeru Nagayama

Makoto Yamada

Hiroki Hanae

Masahiro Kaji

Shigeyoshi Okunishi

Masato Ohtani

An automatic transmission control system includes an automatic transmission provided with a first friction engagement element including friction plates, a piston movable between engaged and disengaged positions for engaging and disengaging, respectively, the friction plates, and engaging and disengaging hydraulic pressure chambers applying engaging and disengaging hydraulic pressure for setting the piston at the engaged and disengaged positions, respectively, first and second hydraulic pressure control valves which adjust the engaging and disengaging hydraulic pressure, respectively, and a controller which controls the first and second hydraulic pressure control valves. When disengaging the engaged first friction engagement element, the controller performs a first control to the first hydraulic pressure control valve to raise the engaging hydraulic pressure, a second control to the second hydraulic pressure control valve to then raise the disengaging hydraulic pressure, and a third control to the first hydraulic pressure control valve to then reduce the engaging hydraulic pressure.

Control system of vehicle including automatic transmission

A control system of a vehicle includes a driving source configured to generate a driving force of the vehicle and transmit the driving force to driving wheels, without intervention of a torque converter, a transmission provided between the driving source and the driving wheels, a friction engagement element used for starting the vehicle, the friction engagement element being provided between the driving source and the driving wheels so as to be engageable and disengageable, and a controller configured to control an engaging force of the friction engagement element to adjust the driving force transmitted from the driving source to the driving wheels. The controller sets a target acceleration of the vehicle based on a rotational speed difference between an input rotational speed and an output rotational speed of the transmission, and controls the engaging force based on the target acceleration.

Vehicle control system

A control system of a vehicle includes an automatic transmission provided with a plurality of friction engagement elements changeable between engaged and disengaged states, and configured to form a plurality of gear stages by changing a combination of three friction engagement elements to be selectively engaged among the friction engagement elements, and a controller which controls the change between the engaged and disengaged states of each friction engagement element. The controller performs a neutral control in which, for setting the automatic transmission to a neutral state in which a driving force of a drive source is not transmitted to driving wheels, while two of the three friction engagement elements engaged when forming each gear stage are kept engaged, the remaining one of the three friction engagement element is disengaged. The two friction engagement elements engaged during the neutral control are common in at least two adjacent gear stages.

A frictional engagement element includes: a first piston, a second piston, a first urging member for urging the first piston in a direction of releasing a friction plate, and a second urging member for urging the second piston in the direction of releasing the friction plate with an urging force larger than the urging force of the first urging member. One of the first and second pistons has a communicating hole for connecting an engaging hydraulic chamber with an opposite hydraulic chamber and the other of the first and second pistons has a valve part for closing the communicating hole. The difference in travel distance between the first and second pistons in motion due to the different urging forces of the first and second urging members causes the valve part to open the communicating hole.

Automatic transmission and frictional engagement element

An automatic transmission includes a piston movable in an axial direction, a plurality of friction plates disposed on a side of a first surface of the piston, a fastening hydraulic chamber applying a hydraulic pressure to a second surface of the piston to move the piston to a fastening position where the friction plates are pressed to be fastened to each other, a release hydraulic chamber applying a hydraulic pressure to the first surface of the piston to move the piston to a release position where the friction plates are released, and a hydraulic pressure control valve that supplies and discharges the hydraulic pressure to and from each of the fastening hydraulic chamber and the release hydraulic chamber. An area of the second surface of the piston for receiving the hydraulic pressure is set to be larger than an area of the first surface for receiving the hydraulic pressure.

Automatic transmission

Provided is a frictional engagement element including: a plurality of friction plates; a piston movable between a releasing position and an engaging position; and a first urging mechanism and a second urging mechanism configured to urge the piston in an engaging direction from the releasing position toward the engaging position. Urging forces of both of the first urging mechanism and the second urging mechanism act on the piston from the releasing position to a first position in the engaging direction. The urging force of the first urging mechanism acts on the piston from the first position to a second position closer to the engaging position than the first position. The first position is a predetermined position where the piston does not abut against the friction plates, and the second position is a position where the piston abuts against the friction plates and the clearances are reduced.

Frictional engagement element and automatic transmission

A method of controlling an automatic transmission is provided. The automatic transmission includes a piston having first and second surfaces opposite from each other, friction plates, engaging and disengaging hydraulic pressure chambers for supplying hydraulic pressure and directing the piston to push the friction plates to be engaged and disengaged, a hydraulic pressure control valve for supplying and discharging hydraulic pressure to and from the chambers, and first and second oil paths communicating the valve with the chambers. The second surface has a larger area for receiving hydraulic pressure than that of the first surface. The method includes controlling the friction plates to change from the disengaged state to the engaged state. Controlling the friction plates includes adjusting the hydraulic pressure to a first instruction pressure in a first period in response to a gear shift command, and to a second instruction pressure in a second period.

Method and device for controlling automatic transmission

A method of controlling an automatic transmission is provided. The automatic transmission includes a piston having first and second surfaces opposite from each other, friction plates, engaging and disengaging hydraulic pressure chambers for supplying and discharging hydraulic pressure and directing the piston to push the friction plates to be engaged and disengaged, a hydraulic pressure control valve for supplying and discharging hydraulic pressure to and from the chambers, first and second oil paths communicating the valve with the chambers, and a pressure reducing valve disposed in the second oil path and for preventing hydraulic pressure of the disengaging hydraulic pressure chamber from exceeding a given set pressure. The second surface has a larger area for receiving hydraulic pressure than an area of the first surface for receiving hydraulic pressure. The method includes changing the given set pressure according to information regarding a state of the automatic transmission.

A method of controlling an automatic transmission is provided. The automatic transmission includes first and second frictional engageable elements and a hydraulic mechanism. The method includes controlling a first hydraulic pressure control valve of the first element to adjust hydraulic pressure to a given value in a first period in response to the gear shift command and increase the hydraulic pressure until first friction plates engaged in a second period, and a second hydraulic pressure control valve of the second element to pre-charge in response to the gear shift command, maintain the hydraulic pressure at a lower value than a highest target value immediately after the pre-charging, and increase the hydraulic pressure until second friction plates engaged immediately after the maintaining the pressure, a time length of the first period being shorter than a time length between a start of the pre-charging and a start of the increasing the pressure.

A method of controlling an automatic transmission is provided. The automatic transmission includes a piston having first and second surfaces opposite from each other, friction plates, engaging and disengaging hydraulic pressure chambers for supplying/discharging hydraulic pressure and directing the piston to push the friction plates to be engaged and disengaged, a hydraulic pressure control valve for supplying/discharging hydraulic pressure to/from the chambers, and first and second oil paths communicating the valve with the chambers. The second surface has a larger area for receiving hydraulic pressure than the first surface. The method includes controlling the disengaged friction plates to be engaged by adjusting the hydraulic pressure to a first pressure in a first period in response to a gear shift command and adjusting the hydraulic pressure to a second pressure in a second period. The first pressure is changed depending on a state of the automatic transmission.

Provided is an automatic transmission including: an input section to which power generated by a drive source is input; an output section configured to output a drive force; and a gear shifting mechanism configured to change a gear ratio. The power is input to the input section without intervention of a hydraulic power transmission device. The gear shifting mechanism includes a predetermined frictional engagement element for achieving a starting gear ratio of a vehicle. The frictional engagement element includes: a plurality of friction plates arranged with clearances therebetween; a piston movable between a releasing position where the friction plates are brought into a released state, and an engaging position where the friction plates are brought into an engaged state by pressing the friction plates; and an urging mechanism configured to urge the piston so that the piston abuts against the friction plates and the clearances are reduced.

A method of controlling an automatic transmission mounted on a vehicle having an automatic engine stop mechanism for automatically stopping and restarting an engine, is provided. The transmission includes a piston having first and second surfaces, friction plates, engaging and disengaging hydraulic pressure chambers, a hydraulic pressure control valve for supplying/discharging hydraulic pressure to/from the chambers, first and second oil paths communicating the control valve with the chambers, a pressure reducing valve for preventing pressure of the disengaging chamber from exceeding a given set pressure, a hydraulic pressure supply device for supplying pressure to the control valve in the automatic stop state, and a mechanical oil pump for supplying pressure to the control valve while the engine is driving, the second surface having a larger pressure receiving area than the first surface. The method includes adjusting the set pressure to be lower in the automatic stop state than while driving.

The present application discloses a control device for an automatic transmission mounted in a vehicle including idling stop means for automatically stopping an engine when a predetermined stop condition is satisfied, and restarting the engine when a predetermined restart condition is satisfied in an engine automatically stopped state. The control device for the automatic transmission includes a first friction element and a second friction element fastened in a starting stage of the automatic transmission; and hydraulic-pressure controlling means for controlling hydraulic pressure for fastening the first and second friction elements. The first friction element includes a return spring that urges a piston of the first friction element to a release side. The second friction element includes a friction plate, a pressing piston that presses the friction plate, and a clearance adjustment piston that supports the pressing piston so as to allow relative movement of the pressing piston.

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Hiroshima, Japan

Manabu Sasahara