Enhanced eductor design

Abstract

The present invention provides for an enhanced eductor element that significantly increases the amount of pressure generated at the siphon tube without significantly increasing the flow resistance through the eductor. The invention further provides for breath-actuated inhalation devices comprising the enhanced eductor element as an actuation mechanism.

1 - 23 . (canceled) 
     
     
         23 . An enhanced eductor element comprising:
 a conduit comprising an inner surface, an outer surface, an inlet, an outlet, and a hollow bore extending between the inlet and the outlet, the bore tapering in a constriction zone between the inlet and the outlet;   a modification member in the constriction zone and protruding from the inner surface to locally reduce a cross-sectional area of the constriction zone; and   a siphon channel providing fluid communication between a siphon inlet at the conduit outer surface and a siphon outlet at the conduit inner surface, the siphon outlet being positioned adjacent to the modification member;   wherein the modification member is configured to increase a siphon pressure drop at the siphon inlet without a substantial increase in a pressure drop across the eductor element.   
     
     
         25 . The eductor element of claim  1 , wherein the modification member comprises a bump on the inner surface of the conduit in the constriction zone. 
     
     
         26 . The eductor element of claim  1 , wherein the modification member comprises a conical bump and the siphon channel extends to an apex of the conical bump. 
     
     
         27 . The eductor element of claim  1 , wherein at least a portion of the modification member is disposed intermediate the conduit inlet and the siphon outlet in the constriction zone. 
     
     
         28 . The eductor element of claim  1 , wherein the siphon channel extends through the modification member to the inner surface. 
     
     
         29 . The eductor element of claim  1 , wherein the constriction zone defines a first diameter, the first diameter being constant throughout the constriction zone. 
     
     
         30 . The eductor element of claim  1 , wherein the constriction zone defines a first diameter that is smaller than diameters of the bore at the inlet and at the outlet 
     
     
         31 . The eductor element of claim  1 , wherein an inner surface of the bore defines a generally smooth continuous curvilinear surface. 
     
     
         32 . The eductor element of claim  1 , wherein the modification member defines a height (H) and the constriction zone defines a radius (R), wherein the modification member height (H) does not exceed 0.65 of the constriction zone radius (R). 
     
     
         33 . The eductor element of claim  9 , wherein a ratio of the modification member height (H) to the constriction zone radius (R) is between about 0.16 and about 0.55. 
     
     
         34 . The eductor element of claim  1 , wherein a length (L) of the modification member along a longitudinal axis of the eductor element and a length (Lcz) of the constriction zone along the longitudinal axis, wherein the modification member length (L) does not exceed 0.75 of the constriction zone length (Lcz). 
     
     
         35 . The eductor element of claim  11 , wherein a ratio of the modification member length (L) to the constriction zone length (LCz) is between about 0.25 and about 0.75. 
     
     
         36 . The eductor element of claim  1 , wherein the modification member defines a length (L) along a longitudinal axis of the eductor element and the constriction zone defines a radius (R), wherein a ratio of the modification member length (L) to the constriction zone radius (R) is between about 1.2 and about 3.0. 
     
     
         37 . The eductor element of claim  1 , wherein the modification member locally reduces the cross-sectional area of the constriction zone by 21% or less. 
     
     
         38 . The eductor element of claim  1 , wherein a perimeter of the modification member extends along between about 60 and about 120 degrees of a radius (R) of the constriction zone. 
     
     
         39 . The eductor element of claim  1 , wherein presence of the modification member restricts airflow through the hollow bore by 10% or less when compared to an eductor element without a modification member, but having the same inlet and outlet diameters, the same constriction zone diameter, and the same overall eductor length (LE) as the eductor element. 
     
     
         40 . The eductor element of claim  1 , wherein the modification member increases the siphon pressure drop as a function of flow rate. 
     
     
         41 . The eductor element of claim  1 , wherein flow through the hollow bore is restricted by the modification member by no more than 10% when compared to an eductor element without the modification member. 
     
     
         42 . A breath-actuated inhalation device comprising the eductor element of claim  1 , wherein the conduit is not positioned along a medicament flow path of the device. 
     
     
         43 . A breath-actuated inhalation device comprising the eductor element of claim  1 , wherein air flowing through the eductor element with an inspiratory breath, is sufficient to cause the siphon pressure drop and actuate the device.