Comparison of energy consumption and power losses of a conventionally controlled CVT with a Servo-Hydraulic Controlled CVT and with a belt and chain as the Torque Transmitting Element Siddharth Shastri, Andrew A Frank UC Davis HEV Center 04CVT55

Conventional CVT Control

Conventional CVT Engine driven hydraulic controller Mechanically and electrically complex High pressure bleed off – energy intensive Control Vs Efficiency Idle stop systems?

Servo Hydraulic Control

Electro hydraulic system Pressure on demand Power consumption Idle Stop V Hybrid Applications

UC Davis SHC CVT Setup

Testing Loaded and unloaded tests Characterize each system Energy and Efficiency mapping

Test Setup

Unloaded Tests Ratio Speed (RPM) Pressure (psi)

Optimal operating region

Belt Design

Clamping Pressure

Power Consumption

Power Flow and Losses CVT AC150 Losses Electrical Mechanical 42V 12V ClampRatio Torque Converter Controls Sensors Friction Belt Power Input Power Output Data Flow Diagram

Power consumption of SHC Vs Stock 3000RPM and 100psi

Loaded Tests Torque input (Nm) (psi) Ratio

Efficiency

Chain Vs Belt - Unloaded

Chain Design

Loaded Tests

Conclusions Stock CVT 89.5% efficient SHC system is 50% more efficient The VDT Belt Optimum at Ratio – 3000 RPM Energy intensive below Ratio 1.0 GCI Chain Ratio RPM Linear with respect ratio change Exhibits about ½ the internal losses of the belt at 1:1 - lesser at overdrive

SHC CVT with GCI Chain 94.97% 3% more than SHC CVT with Belt 5.56% more than Stock CVT