1954 13 in April, NSU company successfully developed the first rotary engine;
1958, a series of tests were carried out on the rotary engine;
1960, Wankel rotary engine was first publicly discussed at a seminar of the German Institution of Engineers.
1963, NSU exhibited a new model with Wankel rotor engine at Frankfurt Motor Show.
1964, NSU and Citroen set up a joint venture company COMOBIL in Geneva, and put the rotary engine on the car for the first time, becoming a formal product;
1967, Toyo Industrial Co., Ltd. of Japan also installed rotary engines on Mazda cars and began mass production.
The patent protection period of the rotary engine prototype has long passed.
If everything is a patent of a car factory, it is only an improved patent of a certain model or series, or even just one of the technologies. A patent for a structure. Ignore him. If you want to use a rotary engine, you only need to make some improvements to the existing rotary engine and then apply for a patent yourself.