Recently an oil-hydraulic system has been made which is compact and high-pressured. That causes a steep rise of the system temperature because of the small heat volume and large heat generation. When the system has risen so much, characteristics of the working oil deteriorate and the system is finally dangerous.
It is very important to study a simple and precise way to predict the temperature rise of the system. As the first step, heat generation and heat transfer in an oil-pipe were modeled and calculated in the present paper. The oil-flow dynamics with the heat generation mechanism was modeled one-dimensionally using ordinary differential equations by the Bondgraph method, which is very convenient for modeling and simulation of heat generation because the method is based on the power transmission. On the other hand, the heat transfer in the housing was analyzed three-dimensionally using the partial differential equation of heat conduction. The prediction of the temperature distributions was calculated effectively by coupling these two kinds of equation systems. The simulation result was compared with the result of the commercial code results and they agreed very well.