Pump powered by a polymer transducer

Abstract

The invention provides a pump with a transducer comprising a laminate with a film of a dielectric polymer material arranged between first and second layers of an electrically conductive material so that it is deflectable in response to an electrical field applied between the layers, wherein the laminate is arranged to cause a pumping action upon deflection of the film. The invention further provides a control system for a pump.

1 - 43 . (canceled) 
     
     
         44 . A fluid pump for displacing a fluid medium from an inlet to an exit, the pump comprising a housing forming a path between the inlet and the exit, and a transducer comprising a laminate with a film of a dielectric polymer material arranged between first and second layers of an electrically conductive material so that it is deflectable in response to an electrical field applied between the layers, wherein the laminate is arranged to cause a pumping action upon deflection of the film. 
     
     
         45 . The pump according to  claim 44 , wherein the film has a first surface and an opposite second surface, at least the first surface comprising a surface pattern of raised and depressed surface portions 
     
     
         46 . The fluid pump according to  claim 45 , wherein the surface pattern comprises a super-pattern arises of repeated sub-patterns. 
     
     
         47 . The pump according to  claim 44 , wherein the laminate comprises a multilayer structure with at least two composites, each composite comprising:
 a film made of a dielectric polymer material and having a front surface and a rear surface, the front surface comprising a surface pattern of raised and depressed surface portions, and   a first layer of an electrically conductive material being deposited onto the surface pattern, the electrically conductive layer having a corrugated shape which is formed by the surface pattern of the film.   
     
     
         48 . The pump according to  claim 47 , wherein the transducer is provided with at least three independent active portions, each portion being arranged to enable deformation of the body at different locations along the path. 
     
     
         49 . The pump according to  claim 44 , wherein the laminate is rolled to form an elongated transducer with axially opposite end faces and a cylindrically shaped body portion between the end faces. 
     
     
         50 . The pump according to  claim 49 , wherein the rolled laminate defines a radius of gyration, r g , given by 
       
         
           
             
               
                 
                   r 
                   g 
                 
                 = 
                 
                   
                     I 
                     A 
                   
                 
               
               , 
             
           
         
       
       where I is the area moment of inertia of the rolled transducer, and r g  may be within the range 5 mm to 100 mm, such as within the range 10 mm to 75 mm, such as within the range 25 mm to 50 mm. 
     
     
         51 . The pump according to  claim 49 , wherein the rolled laminate may define a slenderness ratio, λ, given by λ=L/r g , where L is an axial length of the rolled laminate, and λ may be smaller than 20, such as smaller than 10. 
     
     
         52 . The pump according to  claim 44 , wherein the first electrically conductive layer is deposited onto the surface pattern and has a shape of raised and depressed surface portions which is formed by the surface pattern. 
     
     
         53 . The pump according to  claim 44 , wherein the raised and depressed surface portions have a shape which varies periodically along at least one direction of the first surface. 
     
     
         54 . The pump according to  claim 44 , wherein the raised and depressed surface portions have a size which varies periodically along at least one direction of the first surface. 
     
     
         55 . The pump according to  claim 44 , wherein the first electrically conductive layer has a modulus of elasticity being higher than a modulus of elasticity of the film. 
     
     
         56 . The pump according to  claim 44 , wherein the film has a thickness between 90 percent and 110 percent of an average thickness of the film. 
     
     
         57 . The pump according to  claim 44 , wherein the first electrically conductive layer has a thickness which is between 90 percent and 110 percent of an average thickness of the first electrically conductive layer. 
     
     
         58 . The pump according to  claim 52 , wherein the surface pattern comprises waves forming troughs and crests extending in essentially one common direction. 
     
     
         59 . The pump according to  claim 58 , wherein each wave defines a height being a shortest distance between a crest and neighbouring troughs, an average of the heights of the waves is between ⅓ and 20 μm. 
     
     
         60 . The pump according to  claim 44 , wherein the film has an average thickness being between 10 and 200 μm. 
     
     
         61 . The pump according to  claim 44 , wherein the first electrically conductive layer has a thickness in the range of 0.01-0.1 μm. 
     
     
         62 . The pump according to  claim 52 , wherein the second surface is substantially flat. 
     
     
         63 . The pump according to  claim 47 , wherein at least two adjacent composites are arranged with the rear surfaces towards each other. 
     
     
         64 . The pump according to  claim 47 , wherein at least two adjacent composites are arranged with the front surfaces towards each other. 
     
     
         65 . The pump according to  claim 47 , wherein at least two adjacent composites are arranged with the rear surface of one composite towards the front surface of the other composite. 
     
     
         66 . The pump according to  claim 47 , wherein a section of the path is formed by a space between the composites. 
     
     
         67 . The pump according to  claim 44 , comprising at least two check valves arranged in the path to form a pumping space there between. 
     
     
         68 . The pump according to  claim 66 , wherein the valve structure is formed by additional layers of an electrically conductive material on the film of each composite. 
     
     
         69 . The pump according to  claim 68 , wherein the transducer is formed in such a manner that the laminate, in an unsupported state, fulfils Euler's criteria for stability within a normal operating range for the pump. 
     
     
         70 . The pump according to  claim 44 , wherein at least a section of the path is provided in a body of an elastically deformable material, the transducer being arranged to deflect the body upon deflection of the film whereby the path changes volume. 
     
     
         71 . The pump according to  claim 48 , further comprising a control system adapted to provide subsequent activation of one portion after another in a sequence which fulfils a pumping action whereby a fluid is pushed in the path in a flow direction. 
     
     
         72 . The pump according to any of  claim 71 , wherein the body has a build-in tension which presses the path towards a neutral configuration from which it can be pushed against the build-in tension towards an activated configuration by the transducer, 
     
     
         73 . The pump according to  claim 72 , wherein the neutral configuration provides a lower flow resistance in the path than the activated configuration. 
     
     
         74 . The pump according to  claim 72 , wherein the neutral configuration provides a higher flow resistance in the path than the activated configuration. 
     
     
         75 . The pump according to  claim 44 , wherein the transducer is arranged outside the path. 
     
     
         76 . The pump a according to  claim 44 , wherein the transducer is arranged in the path. 
     
     
         77 . The pump according to  claim 76 , wherein the transducer is arranged to cause a volumetric change of a section of the path upon deflection of the film. 
     
     
         78 . The pump according to  claim 49 , comprising at least two check valves arranged on opposite sides of the transducer and providing a uni-directional flow between the inlet and exit, at least one of the valve elements being attached to, or forms part of the end faces. 
     
     
         79 . The pump according to  claim 78 , wherein the cylindrically shaped body portion is hollow and forms part of the path. 
     
     
         80 . The pump according to  claim 78 , comprising a plurality of elongated transducers arranged with end portions of adjacent transducers towards each other in a continuous cylindrical chamber. 
     
     
         81 . The pump according to  claim 78 , wherein the laminate is rolled relative to a surface pattern of at least one of the layers so that the deflection of the film causes radial expansion of the transducer. 
     
     
         82 . The pump according to  claim 78 , wherein the laminate is rolled relative to a surface pattern of at least one of the layers so that the deflection of the film causes axial expansion of the transducer. 
     
     
         83 . The pump according to  claim 44 , comprising a below with an internal space, the transducer being arranged to deflect the below and thus to provide variable volume in the space. 
     
     
         84 . The pump according to  claim 44 , comprising a cylinder forming part of the path and being provided with two check valves arranged to cause a uni-directional flow from the inlet through the cylinder to the exit, and a piston being movable in a cylinder, wherein the transducer is arranged to move the piston relative to the cylinder. 
     
     
         85 . The pump according to  claim 84 , wherein the laminate of the transducer is a plane laminate, and wherein the pump comprises a control system adapted to drive the transformer with a frequency corresponding to a resonance frequency of the plane laminate. 
     
     
         86 . The pump according to  claim 44 , and including a control system adapted to apply a known bias voltage between the layers and simultaneously to determine a measure which is significant for a capacitance of the laminate. 
     
     
         87 . The pump according to  claim 86 , wherein the transducer is arranged to provide deflection of a variable volume chamber. 
     
     
         88 . A control system for a pump according to  claim 44 , the control system being adapted to apply a known bias voltage between the layers and simultaneously to determine a capacitance of a laminate of the pump.