VACUUM DEGREE ESTIMATION SYSTEM OF DOUBLE-TUBE SYSTEM, INTERNAL COMBUSTION ENGINE, AND VACUUM DEGREE ESTIMATION METHOD OF DOUBLE-TUBE STRUCTURE

摘要

PROBLEM TO BE SOLVED: To provide a vacuum degree estimation system of a double-tube structure, an internal combustion engine, and a vacuum degree estimation method of the double-tube structure which can easily determine a vacuum degree of a vacuum state in a double-tube structure which creates a vacuum state between an outer tube and an inner tube of the double-tube in which a fluid can be made to flow.SOLUTION: A vacuum degree estimation system 10 of a double-tube structure creates a vacuum state between an outer tube 21 and an inner tube 22 of a double-tube 20 in which a fluid is made to flow inside an inner tube 22, and includes: temperature measurement means 31 for measuring a temperature T of a fluid made to flow in the inner part of the inner tube 21; and vacuum degree estimation means 32 for estimating a temperature difference ΔT between an inlet side temperature Ti and an outlet side temperature To of the double-tube structure of the fluid measured by this temperature measurement means 31 or estimating the degree of vacuum from the outlet side temperature To of this fluid.SELECTED DRAWING: Figure 1