Apparatus for controlling continuously variable V-belt transmission

Claim 3

A method as claimed in claim 1, further comprising: a step of determining an upper limit value which is displaced toward an upper engine revolution side from the desired value in engine revolution speed and a lower limit value which is displaced toward a lower engine revolution speed from the desired value in engine revolution speed.

Claim 4

A method as claimed in claim 2, further comprising a step of comparing the revolution speed of the drive pulley with the lower limit value; a step of comparing the revolution speed with the upper limit value; a step of setting the shift motor in a state to rotate in one direction so as to increase the reduction ratio of the continuously variable transmission when said revolution speed of the drive pulley is lower than the lower limit value and setting the shift motor in another state to rotate in the opposite direction so as to decrease the reduction ratio when the revolution speed of the drive pulley is not lower than the lower limit value; and a step of turning on the shift motor when the revolution speed is lower than the lower limit value or when the revolution speed of the drive pulley is higher than the upper limit value and of turning off the shift motor when the revolution speed is not lower than the lower limit value and not higher than the upper limit value.

Claim 8

A continuously variable transmission for automotive vehicle including an internal combustion engine, the continuously variable transmission having a V-belt running over a drive and a driven pulley, each having cylinder chamber and two conical discs, one conical disc of the drive pulley being secured to a drive shaft adapted to be driven by the engine, one conical disc of the driven pulley being secured to a driven shaft, the other conical disc of the drive pulley being controllably movable in an axial direction of the drive shaft in response to the fluid pressure in the cylinder chamber thereof, the other conical disc of the driven pulley being controllably movable in an axial direction of the driven shaft in response to the fluid pressure in the cylinder chamber thereof, said continuously variable transmission comprising: pumping means for the hydraulic fluid; a first control valve for regulating the fluid supplied by said pumping means; a second control valve connected to the first control valve to receive the fluid pressure therefrom for regulating fluid supply and discharge to both of the cylinder chambers, said second control valve having a spool by which the reduction ratio of the continuously variable transmission is determined; a lever having a middle portion linked to one end of said spool and adapted to displace said spool, said lever having one end displaceable by the axial position of the other conical disc of said drive pulley; an electric shift motor means for displacing the other end of said lever; a control unit including, means for detecting a revolution speed of the drive pulley and for generating a revolution speed signal indicative of the revolution speed of the drive pulley; means for detecting a parameter indicative of the output torque of the engine and for generating an engine output signal indicative of the parameter; means for determining a desired value in engine revolution speed for any value in the parameter using a predetermined function which defines for any value in the parameter a desired value in engine revolution speed; and means for operating said shift motor to control the reduction ratio of the continuously variable transmission in such a manner as to maintain the revolution speed of the drive shaft in a predetermined relationship with the desired value in engine revolution speed.

Claim 9

A continuously variable transmission for automotive vehicle including an internal combustion engine, the continuously variable transmission having a V-belt running over a drive and a driven pulley, each having cylinder chamber and two conical discs, one conical disc of the drive pulley being secured to a drive shaft adapted to be driven by the engine, one conical disc of the driven pulley being secured to a driven shaft, the other conical disc of the drive pulley being controllably movable in an axial direction of the drive shaft in response to the fluid pressure in the cylinder chamber thereof, the other conical disc of the driven pulley being controllably movable in an axial direction of the driven shaft in response to the fluid pressure in the cylinder chamber thereof, said continuously variable transmission comprising: pumping means for the hydraulic fluid; a first control valve for regulating the fluid supplied by said pumping means; a second control valve connected to the first control valve to receive the fluid pressure therefrom for regulating fluid supply and discharge to both of the cylinder chambers, said second control valve having a spool by which the reduction ratio of the continuously variable transmission is determined; a lever having a middle portion linked to one end of said spool and adapted to displace said spool, said lever having one end displaceable by the axial position of the other conical disc of said drive pulley; an electric shift motor means for displacing the other end of said lever; a control unit including, means for detecting a revolution speed of the drive pulley and for generating a revolution speed signal indicative of the revolution speed of the drive pulley; means for detecting a parameter indicative of the output torque of the engine and for generating an engine output signal indicative of the parameter; means for determining a desired value in engine revolution speed for any value in the parameter using a predetermined function which defines for any value in the parameter a desired value in engine revolution speed; and means for operating said shift motor to control the reduction ratio of the continuously variable transmission in such a manner as to maintain the revolution speed of the drive shaft in a predetermined relationship with the desired value in engine revolution speed.

Claim 10

A continuously variable transmission as claimed in claim 7, wherein said means for determining the desired value in engine revolution speed generates an upper limit signal indicative of an upper limit value which is displaced toward an upper engine revolution speed side from the desired value in engine revolution speed and a lower limit. signal indicative of a lower limit value which is displaced toward a lower engine revolution speed side from the desired value in engine revolution speed.

Claim 11

A continuously variable transmission as claimed in claim 8, wherein said parameter is at least one of the position of a throttle valve, an intake manifold pressure and the amount of fuel supply.

Claim 12

A continuously variable transmission as claimed in claim 8 or 9, wherein said control unit includes first comparator means for comparing the revolution speed signal with the lower limit signal; second comparator means for comparing the revolution speed signal with the upper limit signal; means for setting said shift motor in a state to rotate in one direction as to increase -the reduction ratio when the revolution speed signal is lower than the lower limit signal and for setting said shift motor in another state to rotate in the opposite direction so as to decrease the reduction ratio when the revolution speed signal is not lower than the lower limit signal; and means for turning on said shift motor when the revolution speed signal is lower than the lower limit signal or when the revolution speed signal is higher than the upper limit value and for turning off said shift motor when the revolution speed signal is not lower than the lower limit signal and not higher than the upper limit signal.

Claim 13

A continuously variable transmission as claimed in claim 10, wherein the speed of action of the shift motor is set at a rate higher than that of the axial resulting movement of the other conical disc of the drive pulley.