Method and device for the metered dispensing of a medium

Abstract

A method for metered dispensing of a medium from a container, a dosing pipette (P 1 P 2 ) for removing an exactly predetermined amount of the medium to be inserted into the container, wherein the predetermined amount is adjusted on the dosing pipette (P 1 P 2 ) prior to removal.

The invention claimed is: 
     
       1. A dosing pipette for the metered dispensing of a medium from a container comprising a metering housing, a plunger seated in the housing and axially displaceable therein in a limited manner by rotation of the plunger by a stroke limitation device, the stroke limitation device comprises an interaction between a cam associated with the metering housing and a plurality of grooves of different lengths which are formed axially in an outer surface of the plunger, wherein the cam engages one of the grooves on the outer surface of the plunger thereby (1) determining a volume of the medium to be dispensed and, at the same time, (2) providing anti-twist protection as a result of the interaction between the cam and the associated groove. 
     
     
       2. The dosing pipette as claimed in  claim 1 , wherein at least one of the plurality of grooves has a groove inlet. 
     
     
       3. The dosing pipette as claimed in  claim 1 , wherein the cam is part of a stop ring which is inserted into the metering housing. 
     
     
       4. The dosing pipette as claimed in  claim 3 , wherein the stop ring is flanged into the metering housing. 
     
     
       5. The dosing pipette as claimed in  claim 1 , wherein the cam is inserted into a recess provided radially in the metering housing and projects into a clearance of an axial recess of the metering housing. 
     
     
       6. The dosing pipette as claimed in  claim 5 , wherein the cam is clipped into the recess. 
     
     
       7. The dosing pipette as claimed in  claim 5 , wherein the plunger is supported against the metering housing by an annular lip. 
     
     
       8. The dosing pipette as claimed in  claim 5 , wherein, in the closed position, the plunger seals an intake opening in the metering housing by an end journal. 
     
     
       9. The dosing pipette as claimed in  claim 8 , wherein the end journal is conical. 
     
     
       10. The dosing pipette as claimed in  claim 5 , wherein information for metering volume is located on an upper housing flange of the metering housing, said information interacting with a lug on the plunger. 
     
     
       11. A dosing device for metered dispensing of a medium, comprising:
 a metering housing for receiving a volume of the medium to be dispensed;   a plunger which is axially displaceable in the metering housing in a limited manner over a stroke of movement, the plunger having a plurality of channels of different lengths extending axially in a periphery of the plunger, and   a stroke limitation device comprising a projection associated with the metering housing which is configured to project into and interact with a selected one of the plurality of channels formed in the periphery of the plunger,   wherein the plunger is configured for rotation relative to the metering housing to select one of the plurality of channels, such that the projection projects into and interacts with the selected one of the channels to determine a length of the stroke of movement of the plunger and thereby also the volume of the medium to be dispensed, and to provide anti-twist protection.    
     
     
       12. The dosing device as claimed in claim 11, wherein the plunger is axially displaceable in the metering housing over the stroke of movement from a closed position, in which the plunger seals an intake opening at an end of the metering housing, such that during the movement of the plunger, the projection moves along the selected one of the channels until it abuts against an end of that channel.  
     
     
       13. The dosing device as claimed in claim 12, wherein the plunger seals the intake opening at the end of the metering housing in the closed position via a conical end journal.  
     
     
       14. The dosing device as claimed in claim 11, wherein the metering housing comprises an elongate, generally cylindrical tube having an intake opening at an end thereof for intake of the volume of the medium to be dispensed.  
     
     
       15. The dosing device as claimed in claim 11, wherein each of the plurality of channels has a channel inlet for receiving the projection.  
     
     
       16. The dosing device as claimed in claim 11, wherein the projection is provided on a stop ring mounted on the metering housing.  
     
     
       17. The dosing device as claimed in claim 16, wherein the stop ring forms a flange at an end region of the metering housing.  
     
     
       18. The dosing device as claimed in claim 11, wherein the projection projects into an axial recess of the metering housing within which the plunger is axially displaceable.  
     
     
       19. The dosing device as claimed in claim 18, wherein the plunger is supported against and seals against the axial recess of the metering housing via an annular lip.  
     
     
       20. The dosing device as claimed in claim 11, wherein markings that provide information concerning a metering amount are situated on a housing flange of the metering housing.