| 摘要 |
The device has a base unit 11 containing a motor 12 and a detachable head unit 16 containing a valve 22, driven by the motor, which can interrupt the flow of air being breathed. The head unit can be removed and sterilised without sterilisation of the base. There may be means to randomly control the speed of the valve and the device may comprise more than one valve arranged in series or in parallel. The valve (figs 7-10) may comprise a housing with a flow path and a plug rotatable on a shaft to open and close the path, or may comprise two discs each having a hole which are rotated relative to one another in the air flow. |
