For R23 cryogenic refrigerant, there is no data about its refrigeration capacity, which brings some difficulties to the selection of compressor. In addition, if there is no R23 compressor, replace it with R404A compressor. Therefore, there is a certain gap between the theoretical calculation of low temperature compressor selection (reference R404A) and the actual situation. How to obtain the effective performance parameters of cryogenic compressor can provide more reliable basis for load calculation of different products (mainly non-standard series). After high frequency quenching, the surface hardness of the plate muffler is hrc58-63. 2. Intake and exhaust cams are symmetrical, the deviation of lift at each point from the theoretical lift listed in the drawing shall not exceed 0.03 within the range of 0-61 °, the cumulative deviation within every 10 ° shall not exceed 0.05, and the rest shall not exceed 0.02; 3. The deviation between the cam lift of fuel injection pump and the theoretical lift listed in the figure shall not exceed 0.03 ° in the range of 0-71 ° and the cumulative deviation within every 4 ° shall not exceed 0.03 ° and 0.0 ° respectively 5 ° and the cumulative deviation within every 4 ° shall not exceed 0.05 °.