초록 ▼

A hydraulic control device for controlling a belt-and-pulley type continuously variable transmission for a motor vehicle which has two variable-diameter pulleys connected by a belt, and two hydraulic actuators for changing effective diameters of the pulleys. The hydraulic control device includes a f

A hydraulic control device for controlling a belt-and-pulley type continuously variable transmission for a motor vehicle which has two variable-diameter pulleys connected by a belt, and two hydraulic actuators for changing effective diameters of the pulleys. The hydraulic control device includes a first and a second pressure regulating valve for adjusting a pressure of a fluid supplied from a hydraulic power source, respectively to a first line pressure and a second line pressure lower than the first line pressure, and a CVT shift control valve device for controlling a speed ratio of the transmission. The valve device includes a shift-direction switching directional control valve and a shift-speed control flow control valve. The directional control valve is operable between a first position in which one of the hydraulic actuators communicates with a first pressure line having the first line pressure, while the other actuator communicates with an atmosphere or a second pressure line having a second line pressure, and a second position in which the above-indicated one actuator communicates with the atmosphere or second pressure line while the other actuator communicates with the first pressure line. The flow control valve controls rates of flows of the fluid to and from the actuators, in response to an operation of the directional control valve.

대표청구항 ▼

A hydraulic control device for controlling a belt-and-pulley type continuously variable transmission for an automotive vehicle which includes a first and second rotating shaft, a pair of variable-diameter pulleys provided on the first and second shafts, respectively, a transmission belt connecting t

A hydraulic control device for controlling a belt-and-pulley type continuously variable transmission for an automotive vehicle which includes a first and second rotating shaft, a pair of variable-diameter pulleys provided on the first and second shafts, respectively, a transmission belt connecting the pair of pulleys, and a pair of hydraulic actuators for changing effective diameters of the variable-diameter pulleys, said hydraulic control device comprising: a first and a second pressure regulating valve for adjusting a pressure of a working fluid supplied from a hydraulic power source, respectively to a first line pressure and a second line pressure which is lower than said first line pressure; a first pressure line having said first line pressure; a second pressure line having said second line pressure; a CVT shift control valve device for controlling a speed ratio of said continuously variable transmission, said CVT shift control valve device including a shift-direction switching directional control valve and a shift-speed control flow control valve; said directional control valve being operable between a second position in which a first of said pair of hydraulic actuators communicates with said first pressure line, while a second of said pair of hydraulic actuators communicates with said second pressure line, and a first position in which said first hydraulic actuator communicates with an atmosphere while said second hydraulic actuator communicates with said first pressure line; and said flow control valve controlling a rate of supply flow of the fluid into one of said first and said second hydraulic actuator and a rate of discharge flow of the fluid from the other of said second and first hydraulic actuators, in response to an operation of said directional control valve.