| 摘要 |
A protective cover (50) comprises a plurality of annular members (52) disposed coaxially with each other. A plurality of radial members (53) extending in the radial direction are so installed as to span the adjacent annular members (52, 52). The intervals between the adjacent annular members (52, 52) are larger than those between the adjacent radial members (53, 53) positioned between these annular members (52, 52). |
