Optimal design for cone valve of mechanical-hydraulic dual power engine

Abstract: Heat energy can be converted to hydraulic energy by a traditional engine-pump system（EPS）. However, the EPS has some disadvantages, such as a long transmission line, low efficiency, and a complex and heavy structure. With an integrating traditional internal combustion engine and plunger pump to remove intermediate links, a mechanical-hydraulic dual power engine (MHPE) can convert heat energy to hydraulic energy directly. Therefore, the energy conversion efficiency was improved and the structure was simplified. MHPE can output one of or both machinery and hydraulic powers, and it can be used for excavators, loaders, bulldozers, and other engineering machineries. The distribution valve, the important element of MHPE, can affect the volume efficiency of the system directly by its structure and performance. The 36114ZG4B type six-cylinders radial MHPE was developed. A-H20L type one-way cone valve with the valve disk of 0.07557 kg quality, 0.028 m large diameter, 0.021 m small diameter and 40° angle is used as an inlet valve. A DIF-L20H type one-way cone valve with the valve disk of 0.04672 kg quality, 0.021 m large diameter, 0.016 m small diameter and 45° angle was used as an outlet valve. With the volume efficiency taken as an objective function, the cone valve's working conditions and structure dimensions taken as constraint conditions, and the cone valve's structure parameters taken as optimization variables, an optimization model was established. Based on Adolph's no-impact theory of pump valve, a valve disk's speed cannot exceed the maximum allowable speed. In order to guarantee the normal work of the valve cone, the hydraulic oil's flow rate through valve clearance is not allowed to exceed 6 m/s. iSIGHT software was used to optimize the cone valve's structure with the inlet valve disk result of 0.04076 kg, 0.036 m large diameter, 0.028 m small diameter, and 46° angle as well as the outlet valve disk result of 0.05845 kg, 0.028 m large diameter, 0.021 m small diameter and 49° angle. At the same time, the volume efficiency of the system was simulated and has been found to increase significantly with the optimization: the volume efficiency increased by 5.71% to the maximum point, 98.06%, at about 1300 r/min; the volume efficiency of the system decreased when the rotate speed exceeded 1 300 r/min, which is due to the cone valve's natural frequency is close to the integer times of the operating frequency of the system; and the volume efficiency is stable in the common condition area, which was from 1 200 to 1 400 r/min.