Abstract: Based on the principle of pump structure, adopting the method of dividing controlled volume on the pump skeleton diagram, It is established the differential equation of the actuating medium’s temperature for each controlled volume in the pumps of type CY and SPB in compliance with the law of energy conservation of controlled volume, and it is obtained the rule of temperature variation with time by finding the solution and finally makes analysis and comparison of the self-cooling performance for the pump of type CY and SPB.

Key words: CY pump, Energy conservation, Self-cooling, SPB pump, Controlled volume