Study on mechanical efficiency in a 2D piston pump with rail rotation based on Hertz contact theory

A 2D piston pump's mechanical efficiency is limited at high rotational speeds, in particular, its mechanical efficiency decreases as its load pressure rises. In this paper, the conventional 2D piston pump is redesigned by changing its suspension rotation into rail rotation to decrease mechanical loss. The mechanical efficiency of this new 2D piston pump is studied by building a mathematical model for analyzing the relationship between the load and the mechanical loss caused by the rolling of the cone rollers on the guiding rails. Hertz contact theory is used for the first time for such analysis. Test results prove that the mechanical efficiency of the 2D piston pump with rail rotation is better than that of a 2D piston pump with suspension rotation, with the former's mechanical efficiency increasing with the load. According to theoretical analysis and test results, the material used to manufacture the cone rollers and guiding rails is changed from 45 steel to GCr15 to improve the mechanical efficiency of the developed 2D piston pump further.