Rack and pinon drive for by-pass cartridge

Abstract

A device for mixing a substance comprised of two constituents contained in a cartridge and having a cartridge holder thereabout, the device comprising a plunger rod for pushing the closure member to permit the transfer of a diluent in a first chamber through a by-pass channel to mix with a constituent in a first chamber, the plunger rod being driven by means of a rack and a pinion gear arrangement to prevent overly rapid movement of the plunger rod.

1 . A device for mixing a substance comprised of two constituents, the device comprising:
 a cartridge;   a cartridge holder;   said cartridge having a fluid communication end and an actuation end, said fluid communication end being receivable in said cartridge holder, the tubular container having a first closure member disposed at the fluid communication end, a second closure member disposed at the actuation end, a piston within the container intermediate the first and second closure members, and a by-pass channel for enabling fluid to by-pass the piston when the piston is in the by-pass position;   a plunger rod engageable with the second closure member for moving the second closure member within the cartridge, said plunger rod having a rack gear formed thereon;   a housing, a pinon gear mounted within said housing, said pinon gear being engageable with said rack gear, and a handle connected to said pinion gear.   
     
     
         2 . The device of  claim 1  further including a cap at a distal end of said cartridge, said cap having a piercing member with a fluid passageway therein, and a hydrophobic membrane associated with said passageway to permit the egress of gas therethrough while preventing the passage of liquid. 
     
     
         3 . The device of  claim 1  wherein said handle comprises a thumb wheel, the arrangement being such that a turning of said thumb wheel drives said pinon gear which in turn drives said rack gear to advance said plunger rod. 
     
     
         4 . The device of  claim 3  wherein said housing is screw threadedly engaged with said cartridge holder. 
     
     
         5 . The device of  claim 2  wherein a first chamber is defined between said first closure member and said piston and a second chamber is defined between said second closure member and said piston, said first chamber containing a dry constituent and said second chamber containing a diluent therefore. 
     
     
         6 . The device of  claim 1  wherein said hydrophobic membrane is secured to a top of said cap, said hydrophobic membrane extending over said passageway. 
     
     
         7 . The device of  claim 2  wherein said cap is screw threadedly engaged with said cartridge holder.