Effects of Contact Ratio on Transmission Errors of Trochoidal Gears

Abstract

This article deals with the effects of the contact ratio خµ on transmission errors of trochoidal gears (which consist of a roller gear anda cam gear). First, the experiments and multibody analysis (MBA) for the transmission errors of two types of singlerow trochoidal gears (types A and B gears) were carried out. The type A gear is a commercial trochoidal gear with خµâ€‰= 1.1 and the type B gear is a trochoidal gear with خµâ€‰= 2.1 (by increasing the number of teeth). The experimental and MBA results showed that the peaktopeak value TEPP of the transmission errors of the type B gear (with خµâ€‰= 2.1) was lower than the type A gear (with خµâ€‰= 1.1). The TEPP of types A and B gears increased as the rotational speed of the roller gear increased. However, the increasing rate of the measured TEPP of the type B gear due to an increase of the rotational speed was less than that of the type A gear. Increasing the contact ratio due to an increase in the number of teeth in a singlerow trochoidal gear (such as a type B gear) decreases the strength of the teeth and rollers. To overcome this problem, as a new transmission error reduction method, a doublerow trochoidal gear (type C gear), having two times the contact ratio of the type A singlerow trochoidal gear was presented and its transmission error was examined. The experimental and MBA results showed that the TEPP of the transmission errors of the type C doublerow trochoidal gear were lower than that of the type A singlerow trochoidal gear. Therefore, it is clear that using a doublerow trochoidal gear is effective for reducing the transmission errors of trochoidal gears.