Abstrakt

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 changes significantly. This was caused both by the technical development and legislative actions, as well as the organizational nature promoting the purchace and use of low emission vehicles. Electric vehicles have a completely different sound emission characteristics than conventional cass. 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 devicesemitting warning sound when miving at speed below 30 km/h. Technical development of electric vehicles has created a need of teres dedicated for them. Those tyres are primarily characterized by ow rolling resistance, because tyre rollinr resistance essentially affects the rangeof 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 of electric carsgenerallydiffer 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 laboratoty measurements of tyre/road noise of tyres specially developed for electric and hybtid vehicles. The tests were performed at the Technical University of Gdansk, Poland on the roadwheel facilities equippeg with replica road surfaces including an experimental poroelasticroad surface - PEARS. A wide selection of tyres was tested, including tyres of sizes singnificantly different trom commonly found in conventional care.

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