Patent ID: 6135917
Filing Date: 2000-10-24
Classification: F16H,Y10T

Abstract:
A speed ratio controller for a continuously variable transmission of a vehicle, said vehicle being provided with an engine responsive to an operation of a throttle and with a catalyst for purifying exhaust gas of said engine, said catalyst being activated at a temperature higher than a predetermined catalyst temperature, and said continuously variable transmission transmitting a rotation of said engine to a drive wheel at an arbitrary speed ratio, said controller comprising:a sensor for detecting an activation of said catalyst,a sensor for detecting an engine load,a sensor for detecting a vehicle speed, anda microprocessor programmed to:select a first speed change map when said catalyst is activated, said first speed change map defining a speed ratio according to said vehicle speed and engine load,select a second speed change map when said catalyst is not activated, said second map defining a larger speed ratio than the speed ratio defined in said first speed change map in a range where the vehicle speed is lower than a predetermined vehicle speed and the engine load is lower than a predetermined engine load, andcontrol the speed ratio of said continuously variable transmission based on a selected speed change map,wherein said engine load detecting sensor comprises a sensor for detecting an opening of said throttle, and said microprocessor is further programmed to use said opening of said throttle as said engine load,wherein a relation between the vehicle speed and the speed ratio in said second map for at least one predetermined throttle opening, is set to be identical to a relation between the vehicle speed and the speed ratio in said first speed change map at said at least one predetermined throttle opening.