Hybrid Hydraulic
The FTI CVT architecture is simply adapted for hydraulic energy recovery by the addition of accumulators and flow control valves. This feature can vastly improve vehicle economy and/or performance without the addition of excessive weight and cost. Unlike other hydraulic energy recovery systems, primary hydraulic elements (pump/motor) are already included in the transmission.
Compared to a Series hybrid in which the drive power from the engine is totally converted to hydraulic power before being converted back to drive power with the associated energy losses and heat and noise generation, the FTI Parallel hybrid drive provides all the benefits of energy savings under braking, assisted acceleration and reduction in brake wear, together with low noise and high efficiency as the hydraulic flow is significantly reduced (flow reaches zero at final ratio, i.e., 1:1 or overdrive). As most vehicles spend the majority of their time at this ratio, high efficiency is very important. Efficiency values exceeding 97% have been demonstrated during dynamometer testing of the RWD passenger vehicle CVT at final ratio. Typically, an FTI CVT has comparable weight and envelope dimensions as the transmission it replaces, therefore no vehicle structural modifications are required. The performance benefits of this technology can often result in the vehicle’s engine size being reduced, which gives additional savings that can partially offset the extra cost of the new transmission, accumulators and valves.
Reproduced with permission of the University of Michigan Automotive Research Center
Hybrid Electric
The FTI CVT is readily adapted to parallel or series Hybrid Electric Vehicle (HEV) or pure electric drive-trains. The CVT permits the use of a smaller electric motor and a less costly controller as it provides torque multiplication while the vehicle is accelerating.The block diagram below shows a typical HEV arrangement incorporating the FTI CVT technology. This arrangement allows the IC engine or the electric drive motor (or both in combination) to operate over their most efficient range without the need for clutches or torque converters. The electric motor may also be used in starter, damper and alternator modes to provide regenerative braking. The unique design of the FTI CVT permits compact packaging and results in an economic solution.
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