CVT System Description - Hydraulic Controls
CVT System Description - Hydraulic Controls
Hydraulic Control
The hydraulic control system is controlled by the CVTF pump, the valves, and the solenoid valves. The CVTF pump is driven by the input shaft. The CVTF pump and the input shaft are linked by the CVTF pump drive chain and the sprockets. Fluid from the CVTF pump flows through the pressure high (PH) regulator valve to maintain specified pressure to the drive pulley, the driven pulley, and the manual valve.
The lower valve body assembly includes the main valve body, the secondary valve body, the CVT driven pulley pressure control solenoid valve, the CVT clutch pressure control solenoid valve, and the CVT drive pulley pressure control solenoid valve.
The manual valve body is bolted on the intermediate housing, and houses the manual valve which switches hydraulic pressure to meet with the shift lever position.
Main Valve Body
The main valve body contains the start clutch shift valve, the shift inhibitor valve, the lubrication regulator valve, and the cooler relief valve.
- Start Clutch Shift Valve
When a control system malfunction occurs, the start clutch shift valve receives shift inhibitor pressure (SI) and covers the lubrication pressure bypass circuit port.
- Shift Inhibitor Valve
The shift inhibitor valve switches the fluid passage to switch the start clutch control from electronic control to hydraulic control when the electronic control system is faulty.
- Lubrication Regulator Valve
The lubrication regulator valve stabilizes the lubrication pressure to the internal circuit.
- Cooler Relief Valve
The cooler relief valve stabilizes the CVTF cooler pressure and recirculation pressure to the CVTF cooler and to the internal circuit.
Hydraulic Control (cont'd)
Secondary Valve Body
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.
- PH Regulator Valve
The PH regulator valve maintains hydraulic pressure supplied from the CVTF pump, and supplies PH pressure to the hydraulic control circuit and the lubrication circuit. PH pressure is regulated at the PH regulator valve by PHC pressure from the PHC shift valve.
- PHC Shift Valve
The PHC shift valve supplies PHC pressure to the PH regulator valve to regulate PH pressure in accordance with drive pulley control (DRC) pressure or driven pulley control (DNC) pressure.
- Start Clutch Back-up Valve
When a control system malfunction occurs, the start clutch back-up valve supplies start clutch control B (CCB) pressure based on shift inhibitor (SI) pressure to the start clutch.
- Clutch Reducing Valve
The clutch reducing valve receives PH pressure from the PH regulator valve and regulates clutch reducing (CR) pressure.
- Start Clutch Accumulator Valve
The start clutch accumulator valve stabilizes the hydraulic pressure that is supplied to the start clutch.
CVT Driven Pulley Pressure Control Solenoid Valve
The CVT driven pulley pressure control solenoid valve contains the driven pulley control valve with the solenoid and pulley control valve A. The driven pulley control solenoid valve controls the position of pulley control valve A which applies driven pulley (DN) pressure to the driven pulley.
CVT Drive Pulley Pressure Control Solenoid Valve
The CVT drive pulley pressure control solenoid valve contains the drive pulley control valve with the solenoid and pulley control valve B. The drive pulley control solenoid valve controls the position of pulley control valve B which applies drive pulley (DR) pressure to the drive pulley. The combination of the CVT driven pulley pressure control solenoid valve and the CVT drive pulley pressure control solenoid valve, applies pulley control pressures to the respective pulleys creating complete power transfer, eliminating steel belt slippage and increasing belt life.
CVT Clutch Pressure Control Solenoid Valve
The CVT clutch pressure control solenoid valve, the start clutch pressure control valve, and the solenoid. The CVT clutch pressure control solenoid valve controls start clutch engagement according to the throttle opening.
Hydraulic Control (cont'd)
Manual Valve Body
The manual valve body contains the manual valve and the reverse inhibitor valve. The manual valve body is bolted on the intermediate housing.
- Manual Valve
The manual valve mechanically uncovers/covers the fluid passage according to the shift lever position.
- Reverse Inhibitor Valve
The reverse inhibitor valve is controlled by reverse inhibitor (RI) pressure from the reverse inhibitor solenoid. The reverse inhibitor valve intercepts the hydraulic pressure flowing to the reverse brake while the vehicle is moving forward at speeds over about 6 mph(10 km/h).
