Noise Generated by Tyres Designed for Electric Vehicles - Results of Laboratory Experiments
Invited paper
Technical University of Gdansk
Tuesday 2 june, 2015, 16:00 - 16:20
0.2 Berlin (90)
Abstract:
A few years ago, electric and hybrid vehicles were rarely seen on public roads
and were considered more as exotic curiosities or even as a sign of extravagance
than a practical means of transport. Nowadays the situation has changed
significantly. This was caused both by the technical development and legislative
actions as well as the organizational nature promoting the purchase and use of
low-emission vehicles. Electric vehicles have a completely different sound
emission characteristics than conventional cars. At low speeds, the electric and
hybrid vehicles driven in electric mode are almost noiseless. Ironically, the
noise levels of electric vehicles are so low, that they constitute a safety
threat as cars approach pedestrians without audible warning noise. In the USA,
the legislative work is in progress to introduce obligatory fitting of electric
vehicles with devices emitting warning sound when moving at speeds below 30
km/h.
Technical development of electric vehicles has created a need of tyres dedicated
for them. These tyres are primarily characterized by low rolling resistance,
because tyre rolling resistance essentially affects the range of vehicles,
especially at low and moderate speeds. It is believed that a relatively small
driving range of electric vehicles is a major obstacle in their dissemination.
Tyres for electric cars generally differ from conventional ones in sizes,
patterns and heights of the tread. Due to these differences, the noise generated
by those tyres may also vary.
This paper presents the results of laboratory measurements of tyre/road noise of
tyres specially developed for electric and hybrid vehicles. The tests were
performed at the Technical University of Gdansk, Poland on the roadwheel
facilities equipped with replica road surfaces including an experimental
poroelastic road surface - PERS. Wide selection of tyres were tested including
tyres of sizes significantly different from commonly found in conventional cars.