US Patent 7491046 Piston for a rotary combustion engine

A rotary combustion engine with at least one working unit, which has essentially a peripheral engine housing, a side housing plate on one side, a side housing plate on the power takeoff side, a triangular piston, and an eccentric shaft. The piston is configured of several parts, which are connected to each other. The connection is accomplished by electron-beam welding under vacuum, which yields excellent results as long as certain conditions are met. The one sidewall and the power takeoff sidewall of the piston are preferably welded to a piston housing, as a result of which the casting molds can be of simpler design and simpler contours can be used, which leads to welds of higher quality and to a decrease in the costs of casting.