Analysis of Apex Seal Dynamic Behavior in a Wankel Engine

Abstract

In Wankel engines, the negative aspects are high HC emissions and fuel consumption, as well as leakage and wear caused by the apex seals directly contacting the inner surface of the housing. The position of the apex seals in the seal groove is important. The turning angle of the rotor (piston) corner relative to the housing, the thickness of the seal and the tip radius value are important factors that determine the movement of the apex seal in the groove. Within the scope of this study, a solid model of a Wankel engine with basic geometric dimensions and a 13B Wankel engine used in the RX8 vehicle were created. Using Solidworks software, the height variation between the base of the apex seal and the base of the seal groove was analyzed in both solid models for one cycle. An empirical formula was then derived to give this height variation. From the results obtained, it is seen that the values calculated from the formula coincide with the dynamic analysis results of the solid model and consistently reflect the height change. As the tip radius increased, the height between the seal and the housing decreased. This height changes also increased as the maximum turning angle of the rotor corner relative to the housing and the seal tip radius increased. The minimum tip radius value should be at least half the seal thickness. The increase in the height change caused an increase in the maximum spring force.

Keywords

• Apex Seal
• Sealing Dynamic Analysis
• Spring Force
• Wankel Engine

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