Noise Generated by Tyres Designed for Electric Vehicles - Results of Laboratory Experiments

Invited paper

Jerzy Ejsmont

Technical University of Gdansk

Tuesday 2 june, 2015, 16:00 - 16:20

0.2 Berlin (90)

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.

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