초록 ▼

A lockup control system for an automatic transmission is provided with an electromagnetic valve 11 and a spool valve 13. When the electromagnetic valve 11 is inactive, the spool valve 13 is set so that a pressure at an OFF port 171 of a torque converter 12 is higher than that of an ON port 172, ther

A lockup control system for an automatic transmission is provided with an electromagnetic valve 11 and a spool valve 13. When the electromagnetic valve 11 is inactive, the spool valve 13 is set so that a pressure at an OFF port 171 of a torque converter 12 is higher than that of an ON port 172, thereby opening a lockup clutch mechanism 19. When the electromagnetic valve 11 is activated, its control pressure Pc becomes lower than a secondary pressure PL2and the spool valve 13 is actuated so that the control pressure Pc is supplied to a clutch control chamber 18. As a result, the lockup clutch mechanism 19 is closed, thereby setting the lockup state. At this time, the control pressure Pc acts directly on the clutch control oil chamber 18, so that the lockup clutch mechanism 19 is controlled with high precision.

대표청구항 ▼

A lockup control system for an automatic transmission, comprising: a fluid joint for transmitting a rotary motive power from an input shaft to an output shaft through a fluid; a lockup clutch mechanism for linking said input and output shafts by bypassing said fluid joint, said lockup clutch mechani

A lockup control system for an automatic transmission, comprising: a fluid joint for transmitting a rotary motive power from an input shaft to an output shaft through a fluid; a lockup clutch mechanism for linking said input and output shafts by bypassing said fluid joint, said lockup clutch mechanism having a fluid chamber which controls closed and open states of said lockup clutch mechanism in response to hydraulic pressure introduced therein; a duty-controlled electromagnetic valve for controlling a control hydraulic pressure so as to switch said closed and open states of said lockup clutch mechanism; and a directional control valve switched between first and second states thereof in response to said control hydraulic pressure controlled by said duty-controlled electromagnetic valve, said directional control valve forming a first hydraulic path for providing a predetermined hydraulic pressure to said fluid chamber to open said lockup clutch mechanism in said first state of said directional control valve and a second hydraulic path for providing said control hydraulic pressure to said fluid chamber to close said lockup clutch mechanism in said second state of said directional control valve.