Dry powder aerosolizer

Abstract

A dry powder aerosolizer for both dispersing and investigating the propers, behavior and measurement of airborne particles has a cylinder and a piston head dividing the cylinder into first and second sub-chambers. The first sub-chamber contains a quantity of dry powder and the second sub-chamber has an inlet opening in communication with an input flow controller admitting pressurized air flowing into the first sub-chamber about the periphery of the piston head to aerosolize the dry powder. The aerosolized powder exits the aerosolizer through a flow control tube extending through a square shaft to which the piston head is mounted. An opposite end of the square shaft extends through a Pelton turbine wheel to which a tangential flow of pressurized air is introduced from the input flow controller to cause rotation of the piston head. The input flow controller has a critical orifice and a use passage with appropriate valving connecting the orifice to the aerosolizer to provide a motive source of pressurized air to the turbine wheel and a supply of aerosolizing air to the first sub-chamber under constant pressure conditions.

What is claimed is: 
     
       1. A dry powder aerosolizer, comprising: (a) a hollow body having means for defining a chamber therein;   (b) a piston head dividing said chamber into first and second sub-chambers communicating with each other about the periphery of the piston head, said first sub-chamber adapted to contain a quantity of dry powder, said piston head carrying means exposed to the first sub-chamber for stirring the dry powder upon rotation of the piston head;   (c) means responsive to a motive source of pressurized gas for rotating said piston head; and   (d) means for directing a flow of pressurized gas into the second sub-chamber during rotation of said piston head and thereby about the periphery of the piston head into the first sub-chamber to aerosolize the dry powder and direct same out of the aerosolizer through outlet means.   
     
     
       2. The aerosolizer of claim 1, wherein said rotating means includes an impulse type turbine wheel mounted for rotation in said hollow body to rotate a shaft extending through the turbine wheel and piston head, said outlet means being a flow control needle tube extending through the shaft in communication with said first sub-chamber. 
     
     
       3. The aerosolizer of claim 2, wherein said shaft is of non-circular cross-section interfitting within a hole of corresponding cross-section formed in the center of the turbine wheel. 
     
     
       4. The aerosolizer of claim 2, wherein said shaft is journaled within first and second bearings respectively positioned adjacent the turbine wheel and piston head. 
     
     
       5. The aerosolizer of claim 1, wherein said stirring means includes a series of wedges projecting outwardly at spaced locations from each other from a face of the piston head exposed to the first sub-chamber. 
     
     
       6. The aerosolizer of claim 1, further comprising an end cap mounted to one end of the hollow body to define said first sub-chamber with said piston head, said end cap being transparent to permit visual monitoring of the quantity of dry powder remaining in said first sub-chamber. 
     
     
       7. The aerosolizer of claim 6, further including a protective annular ring mounted to the inner periphery of the hollow body inwardly adjacent the transparent end cap to prevent the piston head from impacting against the end cap. 
     
     
       8. The aerosolizer of claim 4, wherein said second bearing means includes a first cylindrical bearing member of self-lubricating material mounted within said hollow body between the turbine wheel and piston head, and a second cylindrical bearing member of self-lubricating material mounted on said shaft to slidably interfit within said first bearing member. 
     
     
       9. The aerosolizer of claim 8, wherein said first and second bearing members are made of Teflon material or other self-lubricating material (graphite). 
     
     
       10. The aerosolizer of claim 3, wherein said shaft is of square cross-section. 
     
     
       11. The aerosolizer of claim 2, wherein said turbine wheel is a Pelton turbine wheel. 
     
     
       12. The aerosolizer of claim 2, further including first inlet means in said hollow body adjacent the turbine wheel for introducing a tangential flow of said pressurized gas against a series of vanes circumferentially disposed about the periphery of said turbine wheel. 
     
     
       13. The aerosolizer of claim 12, wherein said flow directing means is a second inlet means in said hollow body for introducing a flow of gas into said second sub-chamber. 
     
     
       14. The aerosolizer of claim 12, further comprising an input flow controller having a critical orifice and a use passage extending from said orifice to a pair of outlet passages in respective communication with said first and second inlet means in said aerosolizer. 
     
     
       15. The aerosolizer of claim 14, further including adjusting valve means disposed in said outlet passages for individual adjustment of the controlled flow rate through each outlet passage. 
     
     
       16. The aerosolizer of claim 15, further including a waste passage in communication with said use passage and critical orifice, including a resistive valve and a proportioning valve for controlling the flow rate of pressurized gas from said critical orifice into the use passage.