CVT System Description - General Operation
CVT System Description - General Operation
General Operation
The continuously variable transmission (CVT) is an electronically controlled automatic transmission with drive and driven pulleys, and a steel belt. The CVT provides stepless forward speeds and one in reverse.
Transmission
Around the outside of the flywheel is a ring gear which meshes with the starter drive gear when the engine is being started with the starter motor. The transmission has four parallel shafts: the input shaft, the drive pulley shaft, the driven pulley shaft, and the final drive shaft. The input shaft is connected to the flywheel, which is connected to the IMA motor rotor through the drive plate. This is connected to the end of the engine crankshaft. The drive pulley shaft and the driven pulley shaft consists of movable and fixed face pulleys. Both pulleys are linked by the steel belt.
The input shaft includes the sun gear and the planetary gears with the carrier. The drive pulley shaft includes the drive pulley and the forward clutch. The driven pulley shaft includes the driven pulley, the start clutch, and the secondary drive gear which is integral with the park gear. The final drive shaft is positioned between the secondary drive gear and the final driven gear. The final drive shaft includes the secondary driven gear and the final drive gear which serves to change the rotation direction, because the drive pulley shaft and the driven pulley shaft rotate the same direction. Under certain conditions the planetary gears in the transmission are engaged by the forward clutch and the reverse brake, and power is transmitted from the drive pulley shaft to the driven pulley shaft to provide movement in L, S, D, and R.
Electronic Control
The electronic control system consists of the PCM, sensors, and solenoid valves. Shifting is electronically controlled for comfortable driving under all conditions. The PCM is located in the engine compartment.
Hydraulic Control
The lower valve body assembly includes the main valve body, the secondary valve body, the CVT driven pulley pressure control solenoid valve, the CVT drive pulley pressure control solenoid valve, the CVT clutch pressure control solenoid valve, and the inhibitor solenoid. These valve bodies are positioned on the lower portion of the transmission housing. The manual valve body is bolted on the intermediate housing.
The main valve body contains the start clutch shift valve, the shift inhibitor valve, the lubrication regulator valve, and cooler relief valve. The secondary valve body contains the pressure high (PH) regulator valve, the pressure high control (PHC) shift valve, the start clutch back-up valve, the clutch reducing valve, and the start clutch accumulator valve. The CVT driven pulley pressure control valve contains pulley control valve A and the driven pulley control valve with the solenoid. The CVT drive pulley pressure control valve contains pulley control valve B and the drive pulley control valve with the solenoid. The CVT start clutch pressure control valve consists of the start clutch pressure control valve and the solenoid. These solenoid valves are controlled by the PCM. The manual valve body contains the manual valve and the reverse inhibitor valve.
The CVTF pump is located on the transmission housing, and it is linked with the input shaft by the drive/driven sprockets and the drive chain. The drive/driven pulleys, the forward clutch, and the start clutch receive fluid from their respective feed pipes, and the reverse brake receives fluid from an internal hydraulic circuit.
Shift Control
The PCM controls the shift pulley ratio through the solenoid valves, while receiving input signals from the various sensors and switches located throughout the vehicle. The PCM actuates the CVT driven and drive pulley pressure control solenoid valves to control pulley control valves A and B. Drive pulley pressure is regulated at pulley control valve B and applied to the drive pulley, driven pulley pressure is regulated at pulley control valve A and applied to the driven pulley, and the pulley ratio is changed to their directed ratio.
Gear Selection-Five-position Transmission
The shift lever has five positions; P: PARK, R: REVERSE, N: NEUTRAL, D: DRIVE, S: SECOND non-stage speeds with sport driving mode and 1st through 7th speed stage ranges with S-paddle shift mode.
Starting the engine is possible only in P and N through the use of a slide-type neutral-safety switch.
Gear Selection-Six-position Transmission
The shift lever has six positions; P: PARK, R: REVERSE, N: NEUTRAL, D: DRIVE, S: SECOND, and L: LOW.
Starting the engine is possible only in P and N through the use of a neutral-safety switch.
Automatic Transmission (A/T) Gear Position Indicator
The A/T gear position indicator in the instrument panel shows which shift lever position has been selected.