The present invention is designed for the overcoming the defects of an opening upper portion of a patent (a notice of authorization is CN 105429432 B and the date of authorization proclamation is in 13.Oct. 2017) having a title of 'continuous power output device in superconducting meissner effect process'. The patent CN 105429432 B is called a superconductive generator for short. The upper portionis opened and cannot prevent the gas volatilized by the refrigerant from escaping so that great source and energy waste is caused and the practical value is lacked. An upper hatch cover (1) and a lower portion of a cabin are properly sealed and bonded by employing the low-temperature sealing technology, a refrigerant and a gas inlet and outlet pipeline are reserved, so that the gas escape can beeffectively avoided, the gas liquefaction and purification cost is reduced, the liquid-gas cyclic conversion and utilization of the refrigerant are favorably achieved, and the running mechanical efficiency of the superconducting engine is improved. The specific implementation needs to be performed according to the characteristics of the superconductive generator, for example, the structure, the shape, the size and the like of the upper hatch cover can be determined according to the output power of the engine, and the manufacturing materials of the upper hatch cover have certain low-temperatureresistance characteristics, such as Dewar made of special alloy, low-temperature resistant composite materials and the like.