Abstract: The purpose of the present invention is to prevent an extraction cap from getting detached under high-temperature environments while minimizing the force for attaching the extraction cap under low-temperature environments. A connecting means (7) for connecting a compressor (3) and an extraction cap (5) is composed of first and second connecting portions (7A, 7B). The first connecting portion (7A) has a hook pawl portions (28) at the tip end part of each of a pair of plate-shaped base portions (27) extending in a coupling direction from the extraction cap (5) through on both sides of an intake port portion (10), the hook pawl portions (28) having a triangular cross-sectional shape and including a locking surface (28S) projecting outwardly. The second connecting portion (7B) has an engaging surface (29S) that engages with the locking surfaces (28S).