Abstract: The reduction ratio of a continuously variable transmission is controlled by a stepper motor. The stepper motor is controlled such that each of rotary positions thereof corresponds uniquely to a desired optimum reduction ratio indicative signal indicative of a desired optimum reduction ratio. The desired optimum reduction ratio indicative signal is generated for operating condition of an automotive vehicle.

Abstract: A method and an apparatus controls a reduction ratio of a continuously variable transmission of an automotive vehicle, wherein the reduction ratio is increased when the depression degree of the accelerator pedal is increased rapidly for ensuring quick acceleration. When the depression degree of the accelerator pedal is decreased rapidly, the reduction ratio is held for a predetermined period of time. Under this condition, the reduction ratio may be controlled to accomplish a predetermined deceleration.

Abstract: A method and an apparatus for controlling the reduction ratio of a continuously variable transmission are disclosed wherein normally the reduction ratio is controlled in response to a desired optimum reduction ratio indicative signal obtained by retrieving the data stored in a memory versus engine load and vehicle speed, but when more vehicle acceleration is needed, the reduction ratio is controlled by a corrected desired optimum reduction ratio indicative signal to increase the reduction ratio.

Abstract: A continuously variable V-belt transmission has a change-direction gearing upstream of a drive pulley, and a hydraulic control system. The hydraulic control system comprises a shift control valve for controlling the distribution of fluid pressure between the drive and driven pulleys, a pitot tube for generating an engine revolution speed indicative signal fluid pressure, a pitot tube for generating a drive pulley revolution speed indicative signal fluid pressure indicative of not only of a revolution speed of the drive pulley in the forward direction but also of a revolution speed of the drive pulley in the reverse direction, and a shift prohibiting valve for prohibiting the supply of fluid pressure to at least one of the cylinder chambers of the drive and driven pulley until a difference between the engine revolution speed indicative signal oil pressure and the drive pulley revolution speed indicative oil pressure is less than a predetermined value.

Abstract: A control system for a hydraulic clutch comprises a starting valve and a complete engagement control valve coupled with the starting valve. The starting valve supplies to the clutch a regulated fluid pressure which is elevated in accordance with a revolution speed of an engine when it is in a start fluid pressure regulating state and which is higher than the regulated fluid pressure provided in said start fluid pressure regulating state when it is in said complete engagement fluid pressure regulating state when it is in a complete engagement fluid pressure regulating state. The complete engagement control valve shifts the starting valve from the start fluid pressure regulating state to the complete engagement fluid pressure regulating state when the vehicle speed exceeds a complete engagement vehicle speed.

Abstract: A continuously variable transmission includes a V-belt running over a drive pulley and a driven pulley. Upon rapid shifting in reduction ratio, a line pressure is increased temporarily to provide a proper V-belt gripping force to prevent slipping of the V-belt.

Abstract: The control system comprises a starting valve wherein an engine revolution speed indicative fluid pressure and a start adjustment fluid pressure act on a spool of the valve against each other. The starting valve generates a start pressure to be used as a clutch engagement pressure for a hydraulic clutch. The start adjustment fluid pressure is generated by a start adjustment valve coupled with an electronic control unit. Under the control of the electronic control unit, the start adjustment offsets a variation in the engine revolution fluid pressure when the engine idles with the vehicle at a standstill.

Abstract: A method and an apparatus for controlling the reduction ratio of a continuously variable transmission are disclosed wherein when an actual engine coolant temperature indicative signal is greater than or equal to a predetermined value indicative signal, a desired optimum reduction ratio signal is obtained by retrieving the desired optimum reduction ratio signal data stored in a memory versus an engine load and a vehicle speed. When the actual engine coolant temperature indicative signal is less than the predetermined value indicatiive signal, the same desired optimum reduction ratio signal data are retrieved based on a corrected signal which is obtained by correcting an engine load indicative signal or a vehicle speed indicative signal in order to provide a larger reduction ratio. Alternatively, another optimum reduction ratio signal data are retrieved when the actual engine coolant temperature indicative signal is less than the predetermined value indicative signal.

Abstract: A control system for a continuously variable V-belt transmission is disclosed wherein for the purpose of preventing an undesirable rapid drop in pressure in a cylinder chamber of a drive pulley a flow restrictor is provided to restrict the flow of oil discharged from the cylinder chamber upon rapid change in reduction ratio of the continuously variable V-belt transmission.

Abstract: A maximum reduction ratio maintaining valve is fluidly disposed between a drive pulley and a shift control valve which controls the supply of fluid to and discharge thereof from the drive pulley. The maximum reduction ratio maintaining valve drains the drive pulley to set a reduction ratio between the drive and driven pulleys at the largest reduction ratio to facilitate starting a vehicle.

Abstract: A starting valve has a start fluid pressure regulating state and a complete engagement fluid pressure regulating state and supplies a regulated fluid pressure to a hydraulic clutch. A shift operating mechanism comprises a rod movable within a reduction ratio select range and an overstroke range. A complete engagement control valve has a spool operatively connected with the rod. When the rod is disposed within the reduction ratio select range, the complete engagement control valve renders the starting valve operable in the complete engagement fluid pressure regulating state, while when the rod is disposed within the overstroke range, the complete engagement control valve renders the starting valve operable in the start fluid pressure regulating state.

Abstract: The reduction ratio of a continuously variable transmission is controlled by a shift motor. The shift motor is controlled such that each of rotary positions thereof corresponds uniquely to a desired optimum reduction ratio. Upon detecting a state wherein a rapid shifting is needed, the shift motor is rotated at an increased revolution speed as compared to a normal revolution speed.

Abstract: A hydraulic control system comprises a line pressure regulator valve which uses a spring has non-uniform spring rate. A spring is compressed between a pressure regulating element and a member movable responsive to a reduction ratio between drive and driven pulleys. A length of the spring is varied by the member with variation in the reduction ratio. The line pressure regulator valve generates a line pressure having non-linear characteristic with respect to the variation in the reduction ratio.

Abstract: A continuously variable transmission includes a hydrodynamic device, such as a fluid coupling or a torque converter, having a lock-up clutch. The reduction ratio of the continuously variable transmission is controlled by a shift motor. The shift motor is controlled such that each of rotary positions thereof corresponds uniquely to a desired optimum reduction ratio. Upon detecting a state wherein a rapid down shift is needed, the lock-up clutch is temporarily disengaged to allow the hydrodynamic device to slip during the rapid down shift.