초록 ▼

A control system for a continuously variable transmission for a motor vehicle has a transmission ratio control valve having a spool for controlling oil supplied to a cylinder of a drive pulley to change the transmission ratio. The transmission ratio control valve has chambers at both ends of the spo

A control system for a continuously variable transmission for a motor vehicle has a transmission ratio control valve having a spool for controlling oil supplied to a cylinder of a drive pulley to change the transmission ratio. The transmission ratio control valve has chambers at both ends of the spool. By controlling flow rate of oil supplied to the chambers in accordance with a desired transmission ratio, the spool is shifted, so that the transmission ratio changing rate is controlled. At kickdown of the transmission, two desired value signals are applied to correct the desired transmission ratio and desired transmission ratio changing rate so as to quickly increase the transmission ratio to a value smaller than the desired transmission ratio at the kickdown.

대표청구항 ▼

In a control system for a continuously variable transmission for transmitting power of an internal combustion engine, the transmission having a drive pulley including a hydraulically shiftable first disc and a hydraulic cylinder for operating the disc, a driven pulley including a hydraulically shift

In a control system for a continuously variable transmission for transmitting power of an internal combustion engine, the transmission having a drive pulley including a hydraulically shiftable first disc and a hydraulic cylinder for operating the disc, a driven pulley including a hydraulically shiftable second disc and a hydraulic cylinder for operating the second disc, and a belt engaged with both pulleys, the control system comprising a hydraulic circuit including a pump for supplying oil to both the hydraulic cylinders, a transmission ratio control valve including a shiftable spool for controlling the oil supplied to the cylinder of the drive pulley to change transmission ratio of the transmission to a desired transmission ratio, shifting means for shifting the spool, sensing means for sensing operating conditions of the engine and the transmission and for producing condition signals dependent on the conditions, actual transmission ratio signal producing means responsive to the condition signals for producing an actual transmission ratio signal corresponding to the actual transmission ratio of the transmission, desired transmission ratio signal producing means responsive to the condition signals for producing a desired transmission ratio signal corresponding to a desired transmission ratio, transmission ratio changing speed signal producing means responsive to the actual transmission ratio signal and to the desired transmission ratio signal for producing a transmission ratio changing rate signal corresponding to a transmission ratio changing rate, and control signal producing means responsive to the transmission ratio changing rate signal for producing a control signal for operating the shifting means to shift the spool dependent on the transmission ratio changing rate for changing the actual transmission ratio of the transmission to the desired transmission ratio, the improvement of the control system comprising detecting means responsive to the condition signals for detecting rapid acceleration of the engine and for producing an acceleration signal, desired value signal producing means responsive to the acceleration signal for producing a second desired value signal representing a second desired transmission ratio value smaller than an initial desired transmission ratio value at the rapid acceleration and for producing a first desired value signal representing a first desired transmission ratio value smaller than the second desired transmission ratio value, desired transmission ratio correcting means responsive to the first desired value signal for correcting the desired transmission ratio signal to correspond to the first desired transmission ratio value of the first desired value signal for quickly increasing the actual transmission ratio, said correcting means being further responsive to the second desired value signal for correcting the desired transmission ratio signal to correspond to the second desired transmission ratio value of the second desired value signal for correcting the actual transmission ratio to the second desired transmission ratio value after the actual transmission ratio reaches the first desired transmission ratio value, whereby the actual transmission ratio is quickly increased to a large value so that maximum acceleration is obtained at the rapid acceleration in accordance with driver demand.