Dose metering system for medicament inhaler

A medicament inhaler comprising:

• a mouthpiece for patient inhalation;
• a cover movable about a hinge to open and close the mouthpiece;
• a delivery passageway for directing an inhalation induced air flow through the mouthpiece;
• a channel extending from the delivery passageway;
• a reservoir for containing medicament, the reservoir having a dispensing port connected to the channel;
• a cup received in the channel and movable between the dispensing port and the delivery passageway;
• a cup spring biasing the cup towards one of the dispensing port and the passageway;
• a yoke successively movable between three positions and including a ratchet engaging the cup and preventing movement of the cup when the yoke is in one of the positions and allowing movement of the cup when the yoke is in another of the positions, the yoke further including cam followers;
• a two cams secured to the cover for movement with the cover about the hinge when the cover is moved to open and close the mouthpiece, and wherein each cam includes first, second and third cam surfaces successively spaced further from the hinge;
• and
• a spring biasing each of the cam followers of the yoke against the cam surfaces of the cams such that movement of the cover to open the mouthpiece causes the cam followers of the yoke to successively engage the first, second and third cam surfaces of the cams and move the yoke towards the hinge and successively between the three positions of the yoke, while movement of the cover to close the mouthpiece causes the cam followers of the yoke to return to the first cam surface of the cams and move the yoke away from the hinge and successively back through the three positions of the yoke.