Abstract
RESEACH AND/OR ENGINEERING QUESTIONS/OBJECTIVE
Wet multiple plate clutches consists of friction plates on which friction material is bonded and mating plates which are low steel, as shown in Figure 1. Damage form of wet clutch varies with load form. Load forms are divided roughly into the continuous slip mode in a long time and the inertia energy absorption mode in a short time. In the transmission on industrial vehicle friction material is often worn in the former mode and mating plates are often deformed in the latter mode. The objective of this study was to propose the design method that balanced the strength of two parts according to load form.
METHODOLOGY
The wear of friction material proceeds by a heat repetition on the surface. The T-N curve that represented the relationship between the surface temperature T and the limit engagement frequency N was proposed [1]. By using this T-N curve in the same way as S-N curve on a metal fatigue, the life of friction material could be calculated by the frequency N on the load form and Miner’s law. The deformation of plate might be caused by the surface temperature difference between inside and outside. The thermal stress calculation model and the criteria of deformation on the plate were proposed [2]. In this study the above all processes were expressed by equations and one graph that could judge which part damage might occur earlier on a load form was proposed. This graph will be used for the design that balanced the strength of two parts according to load form.
RESULTS
The main findings were as follows. 1. In case of the continuous slip mode where the inside temperature increased and the outside temperature followed the inside one by heat conduction in the plate, the wear of friction material was the damage form. 2. In case of the inertia energy absorption mode where the inside temperature rapidly increased but the outside temperature could not follow the inside one, the deformation of the plate was the damage form. When the load form was decided, the design that balances the strength of two parts could be achieved by the proposed equations and graph.
LIMITATIONS OF THIS STUDY
In case of automobile the wet clutches in limited slip differential gear are used in the same way as the continuous slip mode and the wet clutches in automatic transmission are used in the same way as the inertia energy absorption mode. The current study is limited to the one for industrial vehicle but will be able to be applied to automobile.
WHAT DOES THE PAPER OFFER THAT IS NEW IN THE FIELD INCLUDING IN COMPARISON TO OTHER WORK BY THE AUTHORS?
The design method considering strength balance of friction plate and mating plate presented in this paper is new proposal for wet clutch. The other works have dealt with only friction plate.
CONCLUSIONS
New design method that balances the strength of friction plate and mating plate was proposed. This idea will be developed and will be applied to wet multiple plate clutches for automobile.
KEYWORDS – Balance Design, Wet Clutch, Load Form, Damage Form, Transmission