Structure Design And Flow Characteristics Analysis Of Herringbone Planetary Gear Pump

Based on intensively studying gear pump construction principle and planetary gear transmission theory, a herringbone planetary gear pump is designed in this paper, which is a new type of gear pump with the advantage of herringbone gear transmission and planetary gear transmission. Compared with conventional gear pump, its advantages are light in weight, small in size, heavy-duty, high stability in transmission and low noise. Therefore, it is meaningful to design the structure of herringbone planetary gear pump, to deeply analysis and the flow characteristic of herringbone planetary gear pump, to optimize structure and improve reliability.According to the tooth shape character of herringbone gear, the whole structure of the herringbone planetary gear pump is rationally designed. To solve the assembly interference of the herringbone planetary gear, the internal gear is designed into combined type and the planet shaft is designed into disconnect type. The flow distributing mechanism is designed, which is consist of valve plate and sealing block. And in the valve plate, the relief oil groove and pressure oil groove are also designed to eliminate trapped oil and reduce leakage.According to the character of helical gear profile curve, the equations of gear involute, dedendum transition curve and spiral are derived. An exact herringbone gear parametric model is established by the built-in parametric design system of Solid works. According to secondary development principle, a herringbone gear CAD modeling system is developed by using Visual Basic integrated geometric parameter calculation, strength check and automatic modeling, which can easily and quickly update the model parameters to accelerate design process and improve efficiency.According to the method to calculate geometric capacity of conventional gear pump and the mesh character of herringbone gear, by using calculus, the flow characteristic formula of one pair of teeth in herringbone planetary gear pump is derived. And then, according to mesh phase difference theory of planetary gear train, the flow characteristic formula of herringbone planetary gear pump is derived. By using Matlab to simulate the flow pulsation, it is concluded that the flow pulsation of herringbone planetary gear pump is lower than conventional gear pump. According to the character of gear pump structure, the gear pump internal leakage ways are analyzed, linkage formula is derived, and proposed the way to reduce leakage by structure design.