초록 ▼

A lockup control valve is provided to control the discharge from the lockup clutch during clutch engagement and a solenoid valve to supply the control pressure to the lockup control valve. The aforesaid lockup control valve has a face on which the oil supply pressure acts during lockup clutch engage

A lockup control valve is provided to control the discharge from the lockup clutch during clutch engagement and a solenoid valve to supply the control pressure to the lockup control valve. The aforesaid lockup control valve has a face on which the oil supply pressure acts during lockup clutch engagement, an opposing face of equal area on which the lockup clutch discharge pressure acts, a face on which the supply pressure from the aforesaid solenoid valve acts, and an opposing face on which a constant pressure acts. The hydraulic controlling system controls the discharge pressure of the lockup clutch during lockup clutch engagement according to the control pressure from the solenoid valve. This maintains a constant relationship between the solenoid pressure and the lockup clutch capacity (pressure difference) and permits precise slip control even if the oil pressure supplied to the lockup clutch fluctuates.

대표청구항 ▼

A hydraulic control system for a lockup clutch comprising: an oil pressure supply source; regulator means for providing a secondary oil pressure; a fluid coupling hydraulically transmitting an engine power to an automatic transmission; a lockup clutch disposed in the fluid coupling, the lockup clutc

A hydraulic control system for a lockup clutch comprising: an oil pressure supply source; regulator means for providing a secondary oil pressure; a fluid coupling hydraulically transmitting an engine power to an automatic transmission; a lockup clutch disposed in the fluid coupling, the lockup clutch defining an apply chamber and a release chamber; a lockup control valve for controlling an amount of engagement of the lockup clutch by a pressure differential between oil pressure in the apply chamber and oil pressure in the release chamber, the lockup control valve having a spool biased by a constant pressure means with first, second, third and fourth oil chambers being formed by the spool; a solenoid valve disposed in an oil path between the first oil chamber and the oil pressure supply source; the second oil chamber connecting the release chamber to the secondary oil pressure and an exhaust port; the third oil chamber connecting the apply chamber to the secondary oil pressure; the fourth oil chamber being connected to the secondary oil pressure; and each of the second and fourth oil chambers having a pressure-receiving face, the second chamber pressure-receiving face and the fourth chamber pressure-receiving face having identical surface areas and respectively acting in a direction of the constant pressure means and a direction opposite thereto.