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WHAT IS RADICALLY NEW ABOUT THE CVET?

CITY DRIVING VS HIGHWAY DRIVING ENGINE EFFICIENCY
A SMALLER ENGINE CAN POWER A CAR WITH THE CVET
HISTORY OF MECHANICAL CVTs
THE CVET vs MECHANICAL CVTs

HISTORY OF MECHANICAL CVTs
In the early 1900s, a mechanical Continuously Variable Transmission (CVT) was conceived. The idea was to keep the engine at high speed which is its most efficient operating point as shown in the graph, while the wheel speed would be controlled through the CVT by continuously varying the CVT’s “gear” ratio. A clutch would still be required while stopped.

There are two main types of CVTs in the market and being introduced through patent issues. One shown below is a belt driven mechanism, with a synthetic/metallic belt between two conic shapes in parallel and a hydraulic system forces the belt to travel along these parallel shapes, changing the ratio of speed and torque transfer.

Mechanical CVT (Early 1900’s)

When the diameter of the motor side is large and the wheel side is small, the transmission has a high “gear” ratio (really a power / torque ratio) to provide the high starting torque required to accelerate. At highway speeds, the diameter of the motor side is small and the wheel side is large, giving the transmission a low “gear” ratio for speed maintenance.

The other type is a 'toroid' mechanism, which also creates a varying transfer ratio through mechanical means, driven by external hydraulic power.

LIMITATIONS OF MECHANICAL CVTs
Many of the major automotive manufacturers have introduced automobiles with CVTs, which have all utilized a mechanically varying linkage to change the effective transfer ratio (gear ratio) between the input and the output.

Unfortunately the mechanical CVTs have very significant mechanical forces which have to be overcome in order to continuously vary the transfer ratio between the input and output of the mechanical CVT. These mechanical forces required to control the CVT reduce the CVT system efficiency.

To a significant degree, the external control force required to change transfer ratios, as well as other mechanical losses, combine in mechanical CVTs to produce a net efficiency gain that is only marginally better than conventional automatic transmissions and can be lower than obtainable by manual transmissions.

CVT technology in use today is based on this design approach. Net result: Little or no efficiency benefit has been derived from the mechanical CVT.

CVT produces marginal mileage improvement

(sometimes mileage decreases relative to manual transmission)

Published Information

The CVET achieves a number of significant advances over present technology.