Fluid film bearing with variable cross-section constraint structure and engine

The invention provides a fluid film bearing with a variable cross-section constraint structure and an engine, and the fluid film bearing comprises a bearing inner ring, a bearing outer ring, a fluid medium injected between the bearing inner ring and the bearing outer ring, and a contact surface formed between a supporting inner ring and the bearing outer ring, a variable cross-section constraint structure is arranged in the axial direction of the rotating shaft in an extending mode and is composed of two or more reducing structures, and the sizes of the reducing structures are gradually reduced towards the side where movement is limited. According to the fluid film bearing, the variable cross-section restraining structure is adopted on the contact face of the bearing outer ring and the bearing inner ring, the fluid film is restrained through the variable cross-section restraining structure, then one-way relative displacement of the bearing outer ring and the bearing inner ring along a rotating shaft is hinder