Abstract: During a downshift of a belt-drive continuously variable transmission, occurring owing to vehicle deceleration, a CVT controller foretells that a slippage between a drive belt and each of primary and secondary variable-width pulleys tends to occur, when a primary pulley pressure is less than a first predetermined pressure level and a primary pulley speed is less than a first predetermined rotational speed. When the belt slippage has been foretold, the CVT controller inhibits the primary pulley pressure from dropping by setting an actual transmission ratio calculated before a set time period from a time when the slippage has been foretold or a transmission ratio of a relatively higher speed side as compared with a ratio-change operating state obtained when the slippage has been foretold, to a desired transmission ratio, or by relatively rising a line pressure as compared with a line pressure level produced when the slippage has been foretold.

Abstract: In case information such as an actual gear ratio is not stored in an EEPROM 28 due to a trouble of a backup power source 29 or like when an initialization operation of a step motor 27 is performed at the time of start of a vehicle or during stoppage of the vehicle, an output torque of an engine is limited before the initialization operation. Thereby, even if an accelerator is depressed during the initialization operation of the step motor 27 in which a sufficient primary pulley pressure cannot be ensured, the output torque of the engine is limited, so that torque inputted to a V-belt type continuously variable transmission is small and slippage does not occurs between the primary pulley and a secondary pulley.

Abstract: A control apparatus for an automatic transmission includes a control section having a normal control section configured to actuate the step motor at a first speed by using a feedback control including an integral control in accordance with the target pulley ratio and the actual pulley ratio, a high speed control section configured to actuate the step motor at a second speed higher than the first speed by an open loop control based on the target pulley ratio, a judgment section configured to judge whether there is a high speed operation request, and a switch section configured to select the normal control performed by the normal control section at a normal condition, and to switch to the high speed control when a switch start condition is satisfied, the switch start condition including a first condition that the judgment section judges there is the high speed operation request.

Abstract: In control apparatus and method for an automotive vehicle, the vehicle having a continuously variable transmission associated with a vehicular engine and including a belt that transmits a revolution of a primary pulley to a secondary pulley that is enabled to make a gear shift by modifying a pulley ratio between the primary and secondary pulleys with a hydraulic, a determination is made as to whether a belt slip between at least one of the primary and the secondary pulleys occurs and an output section outputs a signal to command an engine control unit to increase an engine speed by a predetermined engine speed when the belt slip is determined to occur.

Abstract: A system for controlling a V-belt type CVT is constructed to change a first position of a step motor to a second position of the step motor corresponding to a second target shift ratio if it is determined that the primary-pulley pressure fails to reach a predetermined value. The second target shift ratio is on the high-speed side with respect to a third position of the step motor corresponding to a third target shift ratio to be achieved if it is determined that the primary-pulley pressure reaches the predetermined value.

Abstract: Hydraulic control system and method for an automatic transmission. The hydraulic control system includes a hydraulic pressure source, a flow rate control valve having a spool with an orifice and a drain hole, stroke position determining means, and pressure regulator means. The stroke position determining means determines that the spool is displaced from a large spool-stroke position where a communication area of the drain hole is not less than a first predetermined area, to a small spool-stroke position where the communication area is not more than a second predetermined area. The pressure regulator means regulates a hydraulic oil pressure downstream of the orifice and corrects the hydraulic oil pressure downstream of the orifice by adding a predetermined correction amount for a first predetermined time when the stroke position determining means determines that the spool is displaced from the large stroke position to the small stroke position.

Abstract: A shift control system for a V-belt type continuously variable transmission is provided. The shift control system comprises a controller programmed to store an actual transmission ratio of the continuously variable transmission at stop of an associated vehicle drive source, and inhibit, at restart of the vehicle drive source, an initializing operation for returning an operational position of the shift actuator to a standard position when the actual transmission ratio is more on a high-speed side than a predetermined transmission ratio. A shift control method is also provided.

Abstract: A belt type continuously variable transmission includes a primary pulley (11), a secondary pulley (12), a belt (13) wound around the primary pulley and secondary pulley; a sensor (27, 21) for detecting a vehicle running state; and a controller (1).

Abstract: In hydraulic pressure control apparatus and method for a continuously variable transmission, a line pressure of the continuously variable transmission is developed with a working oil supplied from an oil pump as an original pressure, and a command pressure is set to develop a line pressure target value of the target value in such a manner that the command pressure is maintained at a predetermined small value for a constant time and, thereafter, the value of the command pressure is raised up to the target value when a shift range of the continuously variable transmission is switched from a neutral range to a running range, the command pressure being raised at a rate lower than a step input to suppress an overshoot developed in the actual line pressure.

Abstract: A hydraulic control apparatus for an automatic transmission with a line pressure regulator valve operative to regulate an oil pressure produced by an oil pump and set a line pressure, the hydraulic control apparatus including a control unit outputting a first command for controlling the line pressure regulator valve to set the line pressure to a minimum value immediately after engine start, and a second command for controlling the line pressure regulator valve to set the line pressure to a target value in accordance with increase in engine speed. The control unit is programmed to set the target value of the line pressure to a value smaller than a maximum value of the line pressure and/or reduce a target speed of engine speed, upon start of the engine in a low temperature condition.

Abstract: A belt type continuously variable transmission includes a primary pulley (11), a secondary pulley (12), a belt (13) wound around the primary pulley and secondary pulley; a sensor (27, 21) for detecting a vehicle running state; and a controller (1).

Abstract: In case information such as an actual gear ratio is not stored in an EEPROM 28 due to a trouble of a backup power source 29 or like when an initialization operation of a step motor 27 is performed at the time of start of a vehicle or during stoppage of the vehicle, an output torque of an engine is limited before the initialization operation. Thereby, even if an accelerator is depressed during the initialization operation of the step motor 27 in which a sufficient primary pulley pressure cannot be ensured, the output torque of the engine is limited, so that torque inputted to a V-belt type continuously variable transmission is small and slippage does not occurs between the primary pulley and a secondary pulley.

Abstract: Hydraulic control system and method for an automatic transmission. The hydraulic control system includes a hydraulic pressure source, a flow rate control valve having a spool with an orifice and a drain hole, stroke position determining means, and pressure regulator means. The stroke position determining means determines that the spool is displaced from a large spool-stroke position where a communication area of the drain hole is not less than a first predetermined area, to a small spool-stroke position where the communication area is not more than a second predetermined area. The pressure regulator means regulates a hydraulic oil pressure downstream of the orifice and corrects the hydraulic oil pressure downstream of the orifice by adding a predetermined correction amount for a first predetermined time when the stroke position determining means determines that the spool is displaced from the large stroke position to the small stroke position.

Abstract: A shift control system for a V-belt type continuously variable transmission is provided. The shift control system comprises a controller programmed to store an actual transmission ratio of the continuously variable transmission at stop of an associated vehicle drive source, and inhibit, at restart of the vehicle drive source, an initializing operation for returning an operational position of the shift actuator to a standard position when the actual transmission ratio is more on a high-speed side than a predetermined transmission ratio. A shift control method is also provided.

Abstract: During a downshift of a belt-drive continuously variable transmission, occurring owing to vehicle deceleration, a CVT controller foretells that a slippage between a drive belt and each of primary and secondary variable-width pulleys tends to occur, when a primary pulley pressure is less than a first predetermined pressure level and a primary pulley speed is less than a first predetermined rotational speed. When the belt slippage has been foretold, the CVT controller inhibits the primary pulley pressure from dropping by setting an actual transmission ratio calculated before a set time period from a time when the slippage has been foretold or a transmission ratio of a relatively higher speed side as compared with a ratio-change operating state obtained when the slippage has been foretold, to a desired transmission ratio, or by relatively rising a line pressure as compared with a line pressure level produced when the slippage has been foretold.

Abstract: A shift control system for a V-belt type CVT is constructed to input a target torque signal obtained by estimating engine torque in accordance with vehicle operating conditions and a target shift ratio of the CVT, input an actual torque signal obtained by detecting actual engine torque, synthesize the target and actual torque signals to provide an estimated-torque signal, and control the line pressure in accordance with the estimated-torque signal.

Abstract: A system for controlling a V-belt type CVT is constructed to change a first position of a step motor to a second position of the step motor corresponding to a second target shift ratio if it is determined that the primary-pulley pressure fails to reach a predetermined value. The second target shift ratio is on the high-speed side with respect to a third position of the step motor corresponding to a third target shift ratio to be achieved if it is determined that the primary-pulley pressure reaches the predetermined value.

Abstract: In control apparatus and method for an automotive vehicle, the vehicle having a continuously variable transmission associated with a vehicular engine and including a belt that transmits a revolution of a primary pulley to a secondary pulley that is enabled to make a gear shift by modifying a pulley ratio between the primary and secondary pulleys with a hydraulic, a determination is made as to whether a belt slip between at least one of the primary and the secondary pulleys occurs and an output section outputs a signal to command an engine control unit to increase an engine speed by a predetermined engine speed when the belt slip is determined to occur.