| 摘要 |
An inner protrusion section (60) is formed integrally with a second cylinder member (22) so that: the inner protrusion section (60) protrudes cylindrically from the end surface (221) of the second cylinder member (22), which faces a third cylinder member (23); and the inner protrusion section (60) is connected to the third cylinder member (23). An outer protrusion section (70) is formed integrally with the third cylinder member (23) so that: the outer protrusion section (70) protrudes cylindrically from the end surface (231) of the third cylinder member (23), which faces the second cylinder member (22); the outer protrusion section (70) is connected to the second cylinder member (22); and the inner wall of the outer protrusion section (70) is in contact with the outer wall of the inner protrusion section (60). An inner protrusion section (80) is formed integrally with the second cylinder member (22) so that: the inner protrusion section (80) protrudes cylindrically from the end surface (222) of the second cylinder member (22), which faces a first cylinder member (21); and the inner protrusion section (80) is connected to the first cylinder member (21). An outer protrusion section (90) is formed integrally with the first cylinder member (21) so that the outer protrusion section (90) protrudes cylindrically from the end surface (211) of the first cylinder member (21), which faces the second cylinder member (22); the outer protrusion section (90) is connected to the second cylinder member (22); and the inner wall of the outer protrusion section (90) is in contact with the outer wall of the inner protrusion section (80). |
