Dispensing mechanism for a medical device

摘要

A dispensing mechanism 1, such as for administering a dosage of a medicament from a liquid injector or a powder inhaler, includes a push button dosage setter 7 for setting the dosage of a medicament to be administered, a ram expeller 51 for expelling a medicament from a medicament container and having a circular disc 52 and a rack of teeth 54 which engage with gear wheel teeth of a drive wheel coupling 47 operatively coupled with the dosage setter 7 and expeller 51. The coupling 47 is arranged to convert displacement of the dosage setter 7 into displacement of the expeller 51 in a first direction and includes a ratchet mechanism comprising first and second ratchet wheels 47a,47b facing and independently engaged with first and a second independently moveable resisting pawls 50 to resist displacement of the expelling means in a second direction opposite to said first direction.