The second splash-proof plate 63 is provided above the first splash-proof plate 62 (on the first end portion 50 side) and has a substantially rectangular flat plate shape. A pair of the second splash-proof plates 63 is formed so as to face each other across the central axis L of the cylindrical portion 36, and is disposed so as to extend obliquely downward from the support column portion 61.

The third splash-proof plate 64 is provided above the second splash-proof plate 63 and has substantially the same shape as the first splash-proof plate 62. That is, a pair of the third splash-proof plates 64 is formed so as to face each other across the central axis L of the cylindrical portion 36. The third splash-proof plate 64 has a substantially semicircular plate shape, and is disposed such that a chord is connected to the support column portion 61 and an arc faces outward. The third splash-proof plate 64 is disposed so as to extend obliquely upward from the support column portion 61. Also in the third splash-proof plate 64, similarly to the first splash-proof plate 62, a lowermost portion connected to the support column portion 61 is referred to as a base portion, and a portion located on the uppermost side (first end portion 50 side) is referred to as an upper end portion.

The fourth splash-proof plate 65 is provided to extend downward from between the base portion and the upper end portion of the third splash-proof plate 64. The fourth splash-proof plate has a substantially rectangular flat plate shape. A pair of the fourth splash-proof plates 65 is formed so as to face each other across the central axis L of the cylindrical portion 36.