System for controlling the pressure of oil in a system for a continuously variable transmission
AssigneeFuji Jukogyo Kabushiki Kaisha
InventorYoshihiko Morimoto
Life of this patent
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Abstract
A control system for a continuously variable transmission has a line pressure control valve having ports and a spool for controlling the line pressure of oil supplied to a cylinder of a pulley device to change the transmission ratio. The line pressure control valve has chambers. When a motor vehicle is decelerated at coasting of the vehicle, the spool of the line pressure control valve is shifted by controlling the amount of oil supplied to the chambers of the valve, so that the line pressure increases in accordance with the magnitude of the deceleration.
Claims13
A control system for a continuously variable transmission for transmitting the power of an internal combustion engine to driving wheels of a motor vehicle through a clutch, having a drive pulley having a hydraulically shiftable disc and a first hydraulic cylinder for shifting the disc, a driven pulley having a hydraulically shiftable disc and a second hydraulic cylinder for operating the disc, a belt engaged with both pulleys, a line pressure control valve having ports and a spool, a transmission ratio control valve having ports and a spool, a first hydraulic circuit having a pump for supplying oil to the first cylinder through the line pressure control valve and transmission ratio control valve, the system comprising:
- a second hydraulic circuit for supplying control oil to the line pressure control valve so as to shift the spool thereof;
- control valve means provided in the second hydraulic circuit for controlling amount of the control oil supplied to the line pressure control valve;
- first means for detecting a coasting state of said motor vehicle and for producing a coasting signal;
- second means for detecting the magnitude of deceleration of said motor vehicle and for producing a deceleration signal dependent on the magnitude;
- third means responsive to the coasting signal and to the deceleration signal for operating the control valve means, so that the spool of the line pressure control valve is shifted to increase the line pressure in dependence on said magnitude of the deceleration.
In a control system for a continuously variable transmission for transmitting power of an internal combustion engine to driving wheels of a motor vehicle through a clutch, the transmission having a drive pulley having a hydraulically shiftable disc and a first hydraulic cylinder for shifting the disc, a driven pulley having a hydraulically shiftable disc and a second hydraulic cylinder for operating the disc of the driven pulley, a belt engaged with both pulleys, the control system comprising a line pressure control valve having ports and a spool, a transmission ratio control valve having ports and a spool, a first hydraulic circuit having a pump for supplying oil to the first hydraulic cylinder through the line pressure control valve and transmission ratio control valve to control the transmission ratio of the transmission, the improvement in the control system comprising:
- a second hydraulic circuit for supplying control oil to the line pressure control valve so as to shift the spool of the line pressure control valve to control line pressure in the first hydraulic circuit;
- control valve means provided in the second hydraulic circuit for controlling the control oil supplied to the line pressure control valve;
- first means for detecting a coasting state of said motor vehicle and for producing a coasting signal;
- second means for detecting the magnitude of deceleration of said motor vehicle and for producing a deceleration signal dependent on the magnitude;
- third means responsive to the coasting signal and to the deceleration signal for operating the control valve means so that the spool of the line pressure control valve is shifted to increase the line pressure in dependence on said magnitude of the deceleration.
Dependencies are inferred from the claim text.