Method for controlling a pump means

Abstract

With a method for controlling a diaphragm or piston pump that is actuated by a cam driven by an electric motor and via a ram or connecting rod, a solution is suggested for a simple system construction that enables quantities of metered media to be delivered at the most constantly rate possible. This is achieved in that in order to deliver an approximately constant volume flow of metered medium, the diaphragm or piston of the pump is moved at approximately constant speed during the compression stroke by the driving unit of the cam with consideration for the cam position.

1 . A method for controlling a diaphragm or piston pump that is actuated via a ram or a connecting rod by a cam which is powered by an electric motor, comprising 
 moving the diaphragm or piston of the pump by the drive unit of the cam at approximately constant speed throughout the compression stroke, taking into account the position of the cam, to assure an approximately constant volume flow of the metered medium.    
   
   
       2 . The method of  claim 1 , wherein 
 the drive unit drives the cam during the compression stroke with a rotating speed profile that compensates for temporal cosinusoidal movement of the piston or diaphragm conditioned by the cam.    
   
   
       3 . The method of  claim 1 , wherein 
 the speed profile of the drive unit has approximately the shape      ω( t )=2 /T   D ×(1−(−2 /T   D   ×t+ 1) 2 ) −1/2      in the compression stroke throughout the period of constant diaphragm speed.    
   
   
       4 . The method of  claim 1 , wherein 
 the drive unit moves the cam with a different speed profile, particularly with constant and/or higher speed, during the aspiration stroke.    
   
   
       5 . The method of  claim 1 , wherein 
 the delivered volume flow of metered medium is increased shortly before the end of the compression stroke in order to compensate for the metering gap during the aspiration stroke.    
   
   
       6 . The method of  claim 1 , wherein 
 an EC motor, preferably with integral rotor position sensors, is used as the drive unit.    
   
   
       7 . The method of  claim 1 , wherein 
 in order to control the cam speed, the cam position is captured by a sensor and/or is calculated from position sensor signals that are in the drive unit.