CONTINUOUSLY VARIABLE TRANSAXLE SYSTEM SYSTEM DESCRIPTION


  1. SYSTEM DESCRIPTION


    1. The K312 (CVT) is a fully electrohydraulically controlled steel belt type continuously variable transaxle. This is a highly efficient transaxle that is controlled in conjunction with the engine, contributing to enhanced fuel efficiency and quietness without shift shock.

      In addition, the continuously variable transaxle has the following features:


      • Diagnostic function

      • Fail-safe function when a malfunction occurs

  2. FUNCTION OF MAIN COMPONENTS


    1. The main components of the K312 CVT system are as follows:

      Component Function
      Continuously Variable Transaxle Assembly Shift Solenoid Valve SC Used to switch control of the shift solenoid valve SLU between forward and reverse clutch control and lock-up clutch control.
      Shift Solenoid Valve SL
      Shift Solenoid Valve SLU Performs forward and reverse clutch control or lock-up clutch control depending on the state of the shift solenoid valves SC and SL.
      Shift Solenoid Valve SLP Controls the oil pressure of the primary pulley.
      Shift Solenoid Valve SLS Controls the oil pressure of the secondary pulley.
      Transmission Revolution Sensor (NIN) Detects the primary pulley revolution speed.
      Transmission Revolution Sensor (NOUT) Detects the secondary pulley revolution speed.
      Transmission Revolution Sensor (NT) Detects the input turbine revolution speed.
      CVT Fluid Temperature Sensor Detects the CVT fluid temperature.
      Oil Pressure Sensor Detects the oil pressure for belt clamping force.
      Stop Light Switch Assembly Detects the brake pedal depressing signal.
      Park/Neutral Position Switch Assembly Detects the shift lever position.
      Transmission Control Switch Detects that the shift lever is in M.
      Combination Meter Assembly Shift Position Indicator Indicates the shift lever position.
      Malfunction Indicator Lamp (MIL) Illuminates or blinks to alert the driver that the ECM has detected a malfunction.
      ECM

      • Controls the electronic control of the CVT system.

      • When the ECM detects a malfunction, the ECM makes a diagnosis and memorizes the failed section.
      Airbag Sensor Assembly Yaw Rate Sensor Detects the angle of inclination of the vehicle.
      Brake Actuator Assembly Skid Control ECU

      • Transmits the vehicle speed signal to the ECM.

      • Transmits the operating states of the ABS and VSC to the ECM.

  3. Oil pump with motor assembly operation control


    1. When the engine automatically stops due to the activation of the stop and start system, the engine stop and start ECU operates the oil pump with motor assembly which is installed in the continuously variable transaxle to generate the optimum CVT hydraulic pressure to achieve better CVT response and to allow the vehicle to start out smoothly after automatic engine start.

      Tech Tips


      • For the operational condition of the stop and start system, refer to Click here.

      • The oil pump with motor assembly operates when the CVT fluid temperature is between 25 and 100 °C.

      • When the shift lever is in R or M, the stop and start system does not stop the engine automatically.

      Oil pump with motor assembly operation
      Shift lever position P R N D M
      Brake pedal depressed Operate Does not operate Operate Operate Does not operate
      Brake pedal released Operate Does not operate Operate Operate → Does not operate* Does not operate

      • *: The oil pump with motor assembly operates until the hydraulic pressure of the built-in oil pump in the transaxle exceeds the hydraulic pressure of the oil pump with motor assembly.