Variable-shift schedule control

Visteon looks to improve IC engine efficiency in large hybrid vehicles.

Worldwide demand for fuel-efficient, low-emissions vehicles has motivated the automotive industry to investigate alternative powertrain architectures. The hybrid-electric vehicle (HEV), one alternative currently receiving attention, consists of two separate modes of producing torque and power: a conventional internal-combustion (IC) engine and an electric-drive system (EDS) powered by an electrical energy device such as a battery. The HEV delivers greater fuel economy and lower emissions than conventional engine types by supplementing a downsized IC engine with torque from the EDS. When decelerating, a portion of the kinetic energy from the HEV, normally lost as heat in the brakes, is captured and stored in a battery for later use by the EDS for torque augmentation.

Typically, the HEV powertrain has been proposed for smaller vehicles with low requirements for torque, power, and overall performance. The industry has limited its focus on larger vehicles due to the sizeable increase in the EDS and energy device required for acceptable torque and power performance levels needed while towing and hill climbing. To date, this type of architecture has failed to address the SUV market segment. However, some automakers believe that a large ecological impact can be made by converting pickup trucks and SUVs to hybrid power, rather than offering the smaller, fuel-efficient vehicles that have been used in previous experiments.