Analysis of the flow ripple stochastic characteristics in dual-pump converging system

Single pump flow ripple characteristics associated with its structure had been widely researched. However, dual-pump converging flow ripple characteristics are seldom noticed. This paper aims at investigating the flow ripple properties of dual-pump sources in hydraulic systems. A common algorithm to calculate the sum of two period and piecewise functions with different phase is proposed and the mathematical expression of dual-pump converging flow ripple is derived. The results show that the converging flow ripples are related to the phase difference of two pumps stochastically. This stochastic flow ripple characteristic can be conveyed by a probability density function presented in this paper. Under the geometric or valve plate distributing flow model, the probabilities of low flow ripple are greater than high flow ripple, which means dual-pump converging flow ripple is lower than single pump´s. These illustrate the principles of flow ripple of dual-pump or multi-pump systems, and are meaningful for the flow ripple suppression for combination pump systems.