CVT System Description - Hydraulic Flow
Hydraulic Flow
Distribution of Hydraulic Pressure
As the engine turns, the transmission fluid pump starts to operate. Transmission fluid (HCF-2) is drawn through the transmission fluid strainer (filter) and discharged into the hydraulic circuit as the various pressures described below:
Line pressure from the transmission fluid pump becomes;
- Drive pulley pressure by the drive pulley pressure control, and flows to the drive pulley.
- Driven pulley pressure by the driven pulley pressure control, and flows to the driven pulley.
- Forward clutch pressure by the clutch pressure control, and flows to the forward clutch and reverse brake.
- Torque converter pressure by the lock-up control, and flows to the torque converter.
- Lubrication pressure by the lubrication pressure control, and flows to the lubrication points.
The PCM controls the CVT drive pulley pressure control solenoid valve, the CVT driven pulley pressure control solenoid valve, the CVT clutch pressure control solenoid valve, and the CVT lock-up clutch control solenoid valve, shift solenoid valve B, and the shift solenoid valve.
Hydraulic Pressure Flow Circuit Diagram
N Position
The drive pulley pressure is regulated by the drive pulley pressure control, and flows to the drive pulley. The driven pulley pressure is regulated by the driven pulley pressure control, and flows to the driven pulley.
The PCM controls to regulate the driven pulley pressure higher than the drive pulley pressure. The driven pulley receives the driven pulley pressure higher than the drive pulley pressure applied to the drive pulley, so the pulley ratio is low. The hydraulic pressure is not applied to the forward clutch.
D, S, and L Positions
The clutch pressure control pressure is regulated by the clutch pressure control, flows to the forward clutch as the forward clutch pressure, and the forward clutch is engaged.
The drive pulley pressure is regulated by the drive pulley pressure control, and flows to the drive pulley. The driven pulley pressure is regulated by the driven pulley pressure control, and flows to the driven pulley.
- At low speed range; pulley ratio low, the PCM controls to regulate the driven pulley pressure higher than the drive pulley pressure. The driven pulley receives the driven pulley pressure higher than the drive pulley pressure applied to the drive pulley, so the pulley ratio is low.
- At middle speed range; pulley ratio middle, the PCM controls to regulate the drive pulley pressure and the driven pulley pressure almost same volume. The drive pulley and the driven pulley receive almost same volume pressure, so the pulley ratio is middle.
- At high speed range; pulley ratio high, the PCM controls to regulate the drive pulley pressure higher than the driven pulley pressure. The drive pulley receives the drive pulley pressure higher than the driven pulley pressure applied to the driven pulley, so the pulley ratio is high.
Reverse Inhibitor Control
If the shift lever is shifted to R while the vehicle is moving forward, the PCM controls the clutch pressure control so that the clutch pressure control pressure leading to the reverse brake releases. No power is transmitted to the reverse brake.
R Position
The clutch pressure control pressure is regulated by the clutch pressure control, and flows to the reverse brake as the reverse brake pressure.
P Position
The clutch pressure control pressure is regulated by the clutch pressure control, and flows into the hydraulic circuit, but the clutch pressure control pressure is intercepted at the manual valve. The hydraulic pressure is not applied to the forward clutch and the reverse brake.