In applications such as coal mining, food and underwater operations, low speed high torque high water-based hydraulic motors have the advantages of high power-to-weight ratio and medium compatibility. However, the current high-water-based hydraulic motors still maintain the same flow distribution structure as oil motors and only replace the working medium with high-water-based emulsion instead of hydraulic oil. Traditional flow distribution disc structures use spring force to ensure sealing. Under low speed, high pressure, and high water-based conditions, the flow distribution disc wears heavily, resulting in serious leaks. For high-water-based emulsion drive systems, this paper proposed a valve flow distribution mechanism comprising valves, bearings, and a pentagon-wheel. The motor’s intaking and discharging process is controlled by a check valve, and the opening and closing of the valve is controlled by the pentagon-wheel. Then the paper carried out comparative analysis on flow distribution rules, advantages and disadvantages of eccentric-wheel, cam, and pentagon-wheel flow distribution mechanisms. It is found that the pentagon-wheel flow distribution structure can reduce the concentration of push rod stress and solve the phenomenon of push rod self-rotation jamming. Finally, the superiority of the five-star wheel flow distribution structure was verified by using AMESim. The prototype was prepared and the performance experiment was carried out. The results show that the pressure in the plunger cavity can be quickly established under different speed (10~90 r/min) and pressure (5~21 MPa). Compared with traditional disc flow distribution mechanisms, the leak rate of the valve flow distribution mechanism under high-water-based conditions of 21MPa and 90r/min is only 0.15 mL/min, significantly improving motor volume efficiency.

Most metals including Mg alloys have a longstanding dilemma of strength-ductility trade-off, which is hindering their wider applications. In this study, we propose a gradient heterogeneous grain (GHG) structure for evading this trade-off dilemma and ultrasonic severe surface rolling is attempted to construct this novel structure in ZE41 Mg alloy. Here, the GHG structure combine the benefits of gradient structure and heterogeneous grain structure and introduce large microstructural heterogeneities. Compared to the coarse-grain and heterogeneous-grain structured alloys, the GHG structured one exhibits dramatical enhancement in strength, ductility, and strain hardening capability. To the best of our knowledge, its strength becomes much higher than that of common ZE41 Mg alloys at no reduction in ductility. These unique mechanical properties stem from not only the individual contribution of the heterogeneous structure components including the fine/ultrafine grains and deformed coarse grains but also their synergistic effect via hetero-deformation induced strengthening and hardening effects. In summary, our study provides a feasible way to develop new Mg alloys with high strength and good ductility.