Loose powder inhaler with inhalation-actuated dosing piston

Claim 1

An inhaler for powder products comprising: a) a housing having opposite ends, a charging section and at least one air chamber, one end of the housing defining a mouthpiece for insertion into a user's mouth, said mouthpiece having an internal volume and opening to the outside of the housing; b) piston means slideably mounted in said air chamber for movement between first and second positions toward and away from said one end; said first position being spaced farther from said one end than said second position, said piston means being mounted for said movement from said first position toward the one end of the housing when under an inhaling action by the user with the mouthpiece in the user's mouth; c) at least one connecting orifice connecting the internal volume of said mouthpiece with said chamber; d) elastic means for moving the piston means from said second position to said first position when the piston means is no longer under the inhaling action of the user; e) a charge cavity disposed in said piston means, said cavity having a predetermined volume for receiving a charge of powder; f) a powder reserve chamber in said charging section of said housing, said reserve chamber having a wall thereof defined by said piston means and being aligned with and communicating with said charge cavity when said piston means is in said first position to supply a charge of powder to said cavity; and g) a dispensing passage in said housing aligned with and in communication at one end thereof with said cavity and at another end with the internal volume of said mouthpiece when said piston means is in said second position whereby upon inhalation by the user, the piston means moves from said first position to said second position and the charge in said cavity is dispensed from said cavity into the internal volume of said mouthpiece to be inhaled by the user.