System for the transmission ratio of a continuously variable transmission
AssigneeFuji Jukogyo Kabushiki Kaisha
InventorMotohisa Miyawaki
Life of this patent
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Abstract
A control system for a motor vehicle provided with a continuously variable transmission which has a transmission ratio control valve having a spool for controlling the transmission ratio. During the acceleration of the vehicle, the transmission ratio is quickly reduced in a low vehicle speed range, whereby speed of an engine is kept low compared with a high vehicle speed range.
Claims6
In a control system for a continuously variable transmission for transmitting the power of an internal combustion engine having a throttle valve to driving wheels of a motor vehicle through a clutch, the transmission having a drive pulley including a hydraulically shiftable disc and a first hydraulic cylinder for shifting the disc, a driven pulley including a hydraulically shiftable disc and a second hydraulic cylinder for operating the disc of the driven pulley, and a belt engaged with both pulleys, the control system having a transmission ratio control valve having ports and a shiftable spool, and a first hydraulic circuit having a pump for supplying oil to the first hydraulic cylinder via the transmission ratio control valve and to the second hydraulic cylinder, the improvement in the system comprising:
- first means for detecting operating conditions of said engine and for producing a first signal;
- second means responsive to the first signal for producing a second signal representing a desired transmission ratio for upshifting the transmission;
- calculating means for producing an actual transmission ratio signal representing actual transmission ratio;
- third means responsive to the second signal and to the actual transmission ratio signal for producing a third signal representing transmission ratio changing speed dependent on the difference between the desired and actual transmission ratio;
- said second means sets the second signal to represent a higher transmission ratio changing speed when the transmission is in a large transmission ratio range below a predetermined vehicle speed, and said second means sets the second signal to represent a lower transmission ratio changing speed compared with said higher transmission ratio changing speed when the transmission is in a small transmission ratio range above said predetermined vehicle speed;
- and
- fourth means responsive to the third signal for shifting the spool of the transmission ratio control valve so as to reduce the transmission ratio at a transmission ratio changing speed determined by the third signal.
Dependencies are inferred from the claim text.