Department of Mechanical & Aerospace Engineering

Hybrid vehicles provide a compromise for both improved user functionality and environmental performance, briefly explain

1. 
   The operations of a parallel hybrid drivetrain and why this improves the vehicles environmental performance; and
   

The conventional generator in an IC engine also serves as a motor that powers the drivetrain in a parallel hybrid vehicle directly. When throttle is wide open, such as during acceleration, uphill motion, or overtaking the part acts as a motor and provides an additional load. The current supplied by the motor decreases as throttle closes until it starts functioning as a generator. The generator is driven by the battery which is charged by the camshaft and through regenerative braking by recovering kinetic energy by means of electromagnetic induction.
Hybrid engines save fuel by stopping the conventional engine while idling as they are capable of independently powering start and through its regerative braking system.

2. 
   Why hybrid drives are now being adopted for super/ hyper car applications.
   

Super and hyper cars are now adopting hybrid drives for environmental and performance reasons. New regulations on lightweight cars in EU are making switching to hybrid unavoidable for supercars. In motorsports this has been the case for years now. Notably, hybrid drives aren't compromising performance as they can provide instant torque at lower revs enabling quick acceleration from start and improved overtaking, thereby, flattening the speed-torque curve. This effectively compensates for the low efficiency regions of ICE. So, while engines continue to provide energy, the electric system will provide peak power enabling engines to be smaller.
(7 marks)

Question 3 continued on next page
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Rotary Wankel engines are unique internal combustion power units which have been applied to both luxury saloons and sports cars. Explain:

1.