| 摘要 |
PURPOSE:To close the gas inlet side or the gas outlet side in a wall chamber by a method wherein a wall chamber with a built-in spherical body is provided in a gas passage part, and during inclination or falling down of a device, the spherical body is moved. CONSTITUTION:When a device is inclined or rolled rearwardly, a spherical body 9 is separated away from an arc recessed part 8a of a bed seat 8 and moved to a wall chamber 7a for adhesion thereto to close an outlet passage 12. When it inclines falls down frontwardly, the spherical body 9 is separated away from the arc recessed part 8a of the bed seat 8 and moved to make tight contact with a wall chamber 7b to close the inlet passage 11 side. |
