| 摘要 |
An arrangement is disclosed for, in connection to an inhalation operation, opening and closing an air inlet of a dry powder inhaler device (DPI) provided with a pre-metered dosing member (4). The arrangement requires a certain well-defined minimum pressure differential between a surrounding atmosphere and the airways of the inhaling person to open the inlet for outside air to enter into the interior of the DPI. The arrangement controlling the opening and closing of the air inlet presents a biased flap connected to a biased catch mechanism. The biased flap (16) closes the air inlets (23) of the DPI to the atmosphere by the force exerted by a compression spring (13), which acts on the flap through a mechanism of levers. In order to open the flap a force Fp bigger than the closing force Fc of the spring and lever mechanism must be applied. The necessary force ensues from the pressure differential across the flap resulting when sucking the mouthpiece of the DPI to a certain degree. The catch is through the mechanism of levers released by the flap (16) when the flap opens, and triggers a sequence of events constituting the irreversible process of administering a dose to the user of the inhaler. The mechanism of levers connecting the flap, the spring and the catch uses rounded shapes (14) where moving parts are in contact with each other to minimize contact areas and rubbing effects and to achieve near zero friction losses. The flap is further provided with a counterweight (15) accomplishing the flap and the catch-mechanism to be statically and dynamically balanced, which almost completely eliminates the risk of external forces, e.g., gravitation or blows of the DPI to accidentally trigger the process of administering a dose. |
