The cylindrical portion 36 includes a cylinder portion 40, the screw thread portion 42, and a restricting portion 44. Here, in the cylindrical portion 36, an end portion on the head portion 35 side is referred to as a first end portion 50, and an end portion on a side opposite to the first end portion 50 is referred to as a second end portion 51. That is, the cylindrical portion 36 is connected to and integrated with the head portion 35 at the first end portion 50. The head portion 35 seals the first end portion 50 of the cylindrical portion 36. The cylinder portion 40 of the cylindrical portion 36 is a cylindrical member having a hollow inside in which an end portion on a side opposite to the head portion 35 is opened. The cylindrical portion 36 holds the filter 34 and the splash-proof body 33 inside the cylinder portion 40. The cylinder portion 40 includes through holes 43 and slits 45. Hereinafter, the central axis of the cylindrical portion 36 is defined as a central axis L. and a direction parallel to the central axis L is referred to as an “axial direction of the cylindrical portion 36”. In the axial direction of the cylindrical portion 36, a direction from the second end portion 51 toward the first end portion 50 is defined as an upward direction, and a direction from the first end portion 50 toward the second end portion 51 is defined as a downward direction.