Inhaler flow control mechanism
An inhaler ( 60 ) has a breath actuated trigger mechanism ( 100 ) reactive to an inhalation flow to trigger the release of a substance to be inhaled. The inhaler ( 60 ) has an inspiration flow which is subject to a higher degree of flow governing post-triggering than pre-triggering. This allows the triggering flow rate to be closer to, or even higher than, the governing flow rate of the inhaler.
1. An inhaler comprising:
a breath actuated trigger mechanism reactive to an inhalation flow to trigger the release of a substance to be inhaled into the inhalation flow;
a first fluid flow path within the inhaler carrying part of the inhalation flow;
a flow governor arranged to govern inhalation flow through the first fluid flow path; and,
a second fluid flow path within the inhaler carrying part of the inhalation flow, the second fluid flow path bypassing the flow governor;
in which triggering the trigger mechanism reduces or blocks flow through the second fluid flow path,
in which the second flow path is at least partially blocked by a part of the trigger mechanism after triggering.
2. An inhaler according to claim 1 , in which the trigger mechanism comprises an actuation member configured to support a canister in a pre-triggered position, which actuation member moves to a post-triggered position upon triggering to thereby at least partially block the second flow path.
3. An inhaler according to claim 2 , in which the actuation member defines a valve member, and the inhaler comprises a valve seat for the second flow path, in which in the pre-triggered position of the actuation member the valve member and valve seat are spaced apart, and in the post-triggered position the valve member abuts the valve seat.
4. An inhaler according to claim 3 , in which the valve member and valve seat are shaped to mate upon engagement.
5. An inhaler according to claim 4 , in which the valve member is convex, and the valve seat is concave.
6. An inhaler according to claim 2 , in which the trigger mechanism comprises a toggle mechanism for selectively permitting movement of the actuation member from its pre-triggered position to its post-triggered position.
7. An inhaler according to claim 6 , in which the toggle mechanism comprises a vane positioned in the inhalation flow, the vane being moveable upon inhalation of a user to move the toggle mechanism between a primed condition in which the actuation member is maintained in its pre-triggered position by cooperation with the toggle mechanism and its post-triggered condition in which the toggle mechanism permits movement of the actuation member.
8. An inhaler according to claim 2 , in which the actuation member is an actuation arm that is pivotable about a pivot axis.
9. An inhaler according to claim 8 , in which the actuation arm is configured to at least partially block the second flow path at a position on the opposite side of the canister to the pivot axis.
10. An inhaler according to claim 1 , in which the first flow path has a first flow inlet defined on the inhaler, and the second flow path has a second flow inlet defined on the inhaler, distinct from the first.
11. An inhaler according to claim 10 , comprising a flow outlet for carrying an inhalation flow, in which the first and second flow inlets are adjacent the flow outlet.
12. An inhaler according to claim 10 , in which the first and second flow inlets are on opposites sides of the flow outlet.
13. An inhaler according to claim 11 , comprising a cover member configured to selectively cover the first and second flow inlets and the flow outlet.
14. An inhaler according to claim 1 , in which the trigger mechanism is positioned downstream of the second flow path.
15. An inhaler according to claim 14 , in which the trigger mechanism when it triggers reduces or blocks flow through the second fluid flow path upstream of a canister outlet.