Abstract
The paper deals with the comparative analysis of the results of a steady-state directional control test following a constant radius method of a quadricicle with Internal Combustion Engine (ICE) in the standard version and with electric power train in Electric Version (EV). Micro cars, defined as quadricycles by the European Community Rules, are nowadays more and more popular in use, especially in vast urban areas. Many examples of such quadricycles are electric vehicles. At the same time, kits to convert vehicles into electric cars are being developed and proposed. Two important aspects are addressed in this paper.
First: a performance analysis of a quadricycle, in terms of steady-state directional control through constant radius tests, through an approach which is typically adopted for passenger cars but unusual for micro cars. Picchio SPA is interested in that approach and adopts procedures that are standard in passenger cars production, in order to design and develop safer and handy micro cars.
Second: an evaluation of how the conversion from thermal into electric traction impacts on vehicle behaviour. This conversion, made under criteria of minimum invasivity, implies vehicle modifications in terms of battery pack placement and installation of electric engine and components only. The impact of this intervention on vehicle dynamics is often not taken into account.
The Characteristic Speed of the EV is 45.5km/h on a constant radius of 28m for the inner tyre. On the same radius the ICE vehicle showed a behaviour so close to a neutral steer vehicle that it could easily become, under some particular conditions - like small throttle variations - an oversteer vehicle with a Critical Speed of 47km/h. As expected, the electric drive vehicle has showed a more understeer behaviour than the ICE one, due to the positioning of some batteries under the front sits which has produced a CG moving. The figure 1 illustrates the yaw velocity response to control, showing the Neutral/Oversteer nature of the ICE version and the Understeer nature of the electric one.
Keywords: Quadricycle, EV, Skidpad, Microcar