Hydraulic control device for an automatic transmission

Abstract

Abstract A hydraulic control device which has a check valve controlling hydraulic pressure to a hydraulic actuator. Hydraulic pressure is selectively supplied to one of plural oil passages having different capacity orifices by a switching valve which switches high speed rotation mode and low speed rotation mode. A hydraulic power source and plural oil passages having different capacity orifices are connected to the switching valve which is controlled by hydraulic pressure varying according to vehicle speed. When rotation of the input shaft is low, the switching valve is connected to the oil passage having small capacity orifice, then hydraulic pressure is supplied to the hydraulic actuator through the orifice of small capacity. At this stage, as centrifugal force working on the ball in the check valve is low, the check valve is closed by even small amount of oil supply through the small capacity orifice, and raises hydraulic pressure in the actuator, so the clutch is engaged smoothly. When rotation of the input shaft is high, the switching valve is connected to the oil passage having the large capacity orifice, then hydraulic pressure is supplied to the hydraulic actuator through the large capacity orifice. At this stage, even if centrifugal force works on the ball is large, the check valve is closed by large amount of oil supply through the large capacity orifice, and raises hydraulic pressure in the hydraulic actuator, so the clutch is engaged smoothly.

Inventors

• 👤 Isao Takase
• 👤 Takenori Kano
• 👤 Haruki Takemoto
• 👤 Fumitomo Yokoyama
• 👤 Mamoru Niimi

Bibliographic Details