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The piston ring design using low tangential force to reduce friction loss has become a general trend in engine development - especially in passenger car engine - in recent years. This trend emphasizes the importance of stable sealing function that does not require much tangential force. Thus, it is important to grasp the correct pressure distribution between the ring and the cylinder. Reliable and accurate calculation to understand the pressure distribution has been an issue for many years among the engineers. In this report, we propose a new calculation method based on the piston ring contour in a free condition. Generally, the piston ring contour is calculated to achieve its correspondence to a given pressure distribution. By analyzing inversely, the pressure distribution is calculated when a ring contour is given. But as is well known, the solution is often unstable in inverse analyses. We introduced the idea of the method of least squares to avoid this problem.

In this paper, the current status of the Japanese automotive thermal engineering is stated for overseas engineers. The described contents are based on the paper, reports and comments in the proceedings and journals of the JSAE (SAE of Japan) during 1989 ∼ 1992. The number of submitted papers related to thermal engineering in the JSAE conference during that period are as follows; The number of published reports and comments in the journal of JSAE is 31 from 1989 to June 1992. Main conferences of JSAE usually open in spring and autumn annually, and the total number of JSAE members is about 27,000. The papers are purely related to heat transfer in the engine field. Then, combustion, tribology, exhaust emission etc. are not included because of independence from thermal engineering itself. In addition to mentioned above items, two detailed contents about automotive thermal engineering are explained. Cooling and noise reduction of the engine compartment Automotive air conditioners in Japan