Pump assembly for pumping viscous media, device comprising same, method for producing surface coating agents, and use of a pump assembly

Abstract

Described herein is a pump arrangement for conveying viscous media including a membrane pump having a conveying chamber, a working chamber connectable in a fluid-conducting manner to a source of a pressurized working medium, and a membrane that separates the working chamber from the conveying chamber. A controller valve arrangement is mounted between the working media source and the working chamber, and the membrane is movable back and forth between the working chamber and the conveying chamber by means of actuation of the controller valve arrangement. The pump arrangement has an electronic controller element which is connected in a signal-conducting manner to the controller valve arrangement and is set up to control a compressed air volume in the working chamber by means of actuation of the controller valve arrangement as a function of a flow volume of the medium exiting from the conveying chamber.

1 . A pump arrangement for conveying viscous media, the pump arrangement comprising:
 a membrane pump having a conveying chamber, a working chamber connectable in a fluid-conducting manner to a source of a pressurized working medium, and a membrane that separates the working chamber from the conveying chamber,   wherein a controller valve arrangement is mounted between the source of the pressurized working medium and the working chamber, and the membrane is movable back and forth between the working chamber (and the conveying chamber by means of actuation of the controller valve arrangement, and   wherein the pump arrangement has an electronic controller element which is connected in a signal-conducting manner to the controller valve arrangement and is set up to control a compressed air volume in the working chamber by means of actuation of the controller valve arrangement as a function of a flow volume of a medium exiting from the conveying chamber, wherein the electronic controller element has control characteristics having an amplifying component, an integrating component, and a differentiating component.   
     
     
         2 . The pump arrangement according to  claim 1 , further comprising a sensor, arranged downstream from the conveying chamber, for detecting the flow volume exiting from the conveying chamber, wherein the electronic controller element is connected to the sensor in a signal-conducting manner and is set up to recognize a deviation in the flow volume detected from a predetermined target value (w s ), wherein:
 when the flow volume is below the target value (w s ), the electronic controller element is configured to actuate the controller valve arrangement in order to increase the compressed air volume in the working chamber, and   when the flow volume is above the target value (w s ), the electronic controller element is configured to actuate the controller valve arrangement in order to reduce the compressed air volume in the working chamber.   
     
     
         3 . The pump arrangement according to  claim 1 , wherein the controller valve arrangement has a pneumatically, hydraulically, or electromagnetically actuated adjustment valve. 
     
     
         4 . The pump arrangement according to  claim 1 ,
 wherein the electronic controller element is selected from:
 a PID controller; 
 a state controller, especially with observer; and 
 a fuzzy controller. 
   
     
     
         5 . The pump arrangement according to  claim 2 ,
 wherein the sensor for detection of the flow volume is a mass flow sensor.   
     
     
         6 . The pump arrangement according to  claim 1 ,
 wherein the membrane pump is a double membrane pump, and has a second conveying chamber, a second working chamber connectable in a fluid-conducting manner to the source of the pressurized working medium, and a membrane that separates the second working chamber from the second conveying chamber.   
     
     
         7 . The pump arrangement according to  claim 1 ,
 further comprising a pulsation damper, disposed downstream of the membrane pump, for smoothing the mass flow of the working medium.   
     
     
         8 . The pump arrangement according to  claim 7 , wherein the pulsation damper has a maximum fluid volume corresponding to two to four times, the conveying volume of the membrane pump over half a conveying cycle. 
     
     
         9 . An apparatus for production of surface coating compositions, the apparatus comprising:
 a conveying media source for a viscous medium containing constituents to be dispersed,   a dispersing unit, connected in a fluid-conducting manner to the conveying media source, for producing a dispersion from the viscous medium, and   a pump arrangement, connected in a fluid-conducting manner to the conveying media source and the dispersing unit, for conveying the viscous medium from the conveying media source to the dispersion unit,   wherein the pump arrangement comprises a membrane pump comprising a conveying chamber, a working chamber connectable in a fluid-conducting manner to a source of a pressurized working medium, and a membrane that separates the working chamber from the conveying chamber, wherein a controller valve arrangement is mounted between the source of the pressurized working medium and the working chamber, and the membrane is movable back and forth between the working chamber and the conveying chamber by means of actuation of the controller valve arrangement, wherein the pump arrangement has an electronic controller element which is connected in a signal-conducting manner to the controller valve arrangement and is set up to control a compressed air volume in the working chamber by means of actuation of the controller valve arrangement as a function of a flow volume of a medium exiting from the conveying chamber.   
     
     
         10 . The apparatus according to  claim 9 , wherein the electronic controller element has control characteristics having an amplifying component, an integrating component, and a differentiating component. 
     
     
         11 . The apparatus according to  claim 9 , wherein the pump arrangement further comprises a sensor, arranged downstream from the conveying chamber, for detecting the flow volume exiting from the conveying chamber, wherein the electronic controller element is connected to the sensor in a signal-conducting manner and is set up to recognize a deviation in the flow volume detected from a predetermined target value (w s ), wherein:
 when the flow volume is below the target value (w s ), the electronic controller element is configured to actuate the controller valve arrangement in order to increase the compressed air volume in the working chamber, and   when the flow volume is above the target value (w s ), the electronic controller element is configured to actuate the controller valve arrangement in order to reduce the compressed air volume in the working chamber.   
     
     
         12 . A process for producing a surface coating composition, especially a coating composition for metallic and plastic surfaces, the process comprising the steps of:
 conveying a viscous medium comprising constituents to be dispersed from a conveying media source to a dispersion unit, and   producing a dispersion from the viscous medium by means of the dispersing unit, wherein the step of conveying the viscous medium comprises:   conveying the viscous medium by means of a membrane pump having a conveying chamber for the viscous medium and a working chamber for moving a membrane, by means of which the viscous medium is conveyed through the conveying chamber,   detecting a mass flow rate of the viscous medium leaving the conveying chamber, and   controlling a compressed air volume in the working chamber as a function of the mass flow rate detected.   
     
     
         13 . The process according to  claim 12 , further comprising the steps of:
 recognizing a deviation in the flow rate detected from a predetermined target value (w s ),   increasing the compressed air volume in the working chamber when the flow rate goes below the target value (w s ), and   reducing the compressed air volume in the working chamber when the value flow rate goes above the target value (w s ).   
     
     
         14 . The process according to  claim 12 , further comprising the step of:
 smoothing the mass flow rate of the viscous medium downstream of the membrane pump, and preferably upstream of a sensor used to detect the mass flow rate.   
     
     
         15 . A method for supplying a viscous medium comprising constituents to be dispersed to a dispersing unit, the method comprising using a pump arrangement according to  claim 1 . 
     
     
         16 . The pump arrangement according to  claim 4 , wherein the fuzzy controller comprises input channels extended by an integral component and a differentiating component. 
     
     
         17 . The pump arrangement according to  claim 9 , wherein the pulsation damper has a maximum fluid volume corresponding three times the conveying volume of the membrane pump over half a conveying cycle. 
     
     
         18 . The apparatus according to  claim 9 , wherein the dispersing unit is a stirred mill. 
     
     
         19 . The process according to  claim 12 , wherein the dispersing unit is a stirred mill. 
     
     
         20 . The method according to  claim 15 , wherein the dispersing unit is a stirred mill.