Kunming Yunnei Power Co., Ltd., founded in 1999, is a joint-stock listed company with Yunnan Internal Combustion Engine Factory as the sole sponsor and raised by the society. It has been engaged in diesel engine development and production for more than 60 years. The company is a leading enterprise in the auto parts engine industry in China, a pioneer enterprise in the internal combustion engine industry in China, the second batch of innovative pilot enterprises in China, the first batch of innovative enterprises and high-tech enterprises in Yunnan Province, the "National Enterprise Technology Center" recognized by the National Development and Reform Commission, the "Key High-tech Enterprise in the National Passenger Car Diesel Engine Industrialization Base", the "Key High-tech Enterprise in the National Torch Program" and the "International Science and Technology Cooperation Base", and won the National May 1 Labor Award and the "National Advanced Grassroots Party Organization".
On the engine, the piston does reciprocating linear motion in the cylinder, in which the diameter of the cylinder is referred to as cylinder diameter for short.