Method of controlling speed reduction ratio for a continuously variable speed transmission

Claim 1

A method for controlling a speed reduction ratio of a continuously variable transmission comprising the steps of: determining a predicted acceleration dV o /dt calculated from a reserved power of an engine and a reference change rate dN o /dt of an engine speed obtained based on a parameter representing a driver's intention to accelerate or decelerate, calculating a change rate di/dt of speed reduction ratio by the following equation using the above values di/dt=-C.sub.1 *(N/V.sup.2)*(dV.sub.o /dt)+C.sub.2 *(1/V)*(dN.sub.o /dt) where C 1 and C 2 are constants, and an asterisk ("*") means multiplication, setting a reference engine speed corresponding to said parameter, and controlling the speed reduction ratio using said calculated change rate di/dt of speed reduction ratio as a control value so that an actual engine speed coincides with said reference engine speed; said method further comprising the steps of: keeping the speed reduction ratio unchanged for a prescribed delay time when said parameter is lowered, and then controlling the speed reduction ratio using a change rate corrected by a coefficient K OFF so that, with time, the change rate gradually approaches said calculated change rate di/dt.

Claim 2

A method for controlling a speed reduction ratio of a continuously variable transmission comprising the steps of: determining a predicted acceleration dV o /dt calculated from a reserved power of an engine and a reference change rate dN o /dt of an engine speed obtained based on a parameter representing a driver's intention to accelerate or decelerate, calculating a change rate di/dt of speed reduction ratio by the following equation using the above values di/dt=-C.sub.1 *(N/V.sup.2)*(dV.sub.o /dt)+C.sub.2 *(1/V)*(dN.sub.o /dt) where C 1 and C 2 are constants, and an asterisk ("*") means multiplication, setting a reference engine speed corresponding to said parameter, and controlling the speed reduction ratio using said calculated change rate di/dt of speed reduction ratio as a control value so that an actual engine speed coincides with said reference engine speed; said method further comprising the steps of: keeping the speed reduction ratio unchanged for a prescribed delay time when said parameter is lowered, and then controlling the speed reduction ratio using a change rate corrected by a coefficient K OFF so that, with time, the change rate gradually approaches said calculated change rate di/dt.