Experimental verification methods of the possibility to use unsynchronized gear clutches as controls in automatic planetary gearboxes

Abstract

The analysis of the development of automatic transmissions (AT) shows the desire of developers to reduce by all possible means the loss of power during its transfer from the engine to the drive wheels. The number of controlled friction elements in the off position is one of the main factors affecting the magnitude of the power losses in the gearbox. The smaller the number of the control elements, the higher the efficiency of transmission. Therefore, the leading manufacturers of AT shifted to the kinematic schemes possessing four degrees of freedom. One of the ways to reduce the power losses in the friction controls is a transition to a non-synchronized gear clutches in planetary transmissions. The gear couplings were first used by the German company ZF in the nine-speed gearbox ZF 9HP. It was found that for the synchronization of gear locking clutches and brakes at a lower gear it was necessary to increase the rotation frequency of the driving shaft of the gearbox by an amount equal to the progressive geometrical denominator between two adjacent gears, while the reduction of rotation frequency resulted in the increase of shifting gear by the same amount. The paper presents a methodology of experimental verification of the theoretical research results on Axiline Super Flow Technologies Group test stand. In the course of the experiment it is supposed to carry out the following research: to evaluate the gear coupling synchronization process during the down and up gear shifting in the ICE constant throttle position and during its opening. The presented technique allows to check study results and the possibility to use non-synchronized gear clutches in automatic planetary gearbox as controlling elements.