Diaphragm pump

Abstract

A pump ( 10 ) comprising an inlet ( 12 ), an outlet ( 14 ) and a pumping chamber ( 16 ) between the inlet ( 10 ) and the outlet ( 12 ). The pumping chamber ( 16 ) has first and second opposed interior pumping chamber surfaces ( 18, 20 ) extending from the inlet ( 12 ) to the outlet ( 14 ) in a pumping direction (PD). The pump ( 10 ) also has a flexible diaphragm ( 22 ) between the first and second pumping chamber surfaces ( 18, 20 ) which is adapted to substantially sealingly separate the first and second pumping chamber surfaces ( 18, 20 ) from one another. The diaphragm ( 22 ) has first and second layers ( 24, 26 ) adjacent the first and second pumping chamber surfaces ( 18, 20 ) respectively. A means ( 38 ) is also provided which induces substantially sinusoidal motion in the diaphragm ( 22 ) in the pumping direction (PD) without inducing relative movement between the diaphragm ( 22 ) and the pumping chamber ( 16 ) in the pumping direction (PD). The amplitude of the sinusoidal motion is approximately equal to the distance between the first and second pumping chamber surfaces ( 18, 20 ) in a direction normal to the pumping direction (PD) minus the distance between the sides of the diaphragm first and second layers ( 24, 26 ) adjacent the pumping chamber surfaces ( 18, 20 ). The length of the pumping chamber ( 16 ) in the pumping direction (PD) is greater than or equal to one wavelength of the sinusoidally shaped diaphragm ( 22 ) and the motion inducing means ( 38 ) is, at least in the region of the diaphragm ( 22 ) adjacent the first and second pumping chamber surfaces ( 18, 20 ), disposed within the first and second layers ( 24, 26 ) of the diaphragm ( 22 ).

1 . A pump comprising: 
 an inlet;    an outlet;    a pumping chamber between the inlet and the outlet, the pumping chamber having first and second opposed interior pumping chamber surfaces extending from the inlet to the outlet in a pumping direction;    a flexible diaphragm between the first and second pumping chamber surfaces and adapted to substantially sealingly separate the first and second pumping chamber surfaces from one another, the diaphragm having first and second outer layers disposed adjacent the first and second pumping chamber surfaces respectively; and    means to induce substantially sinusoidal motion in the diaphragm in the pumping direction without inducing relative movement between the diaphragm and the pumping chamber in the pumping direction, the amplitude of the sinusoidal motion being approximately equal to the distance between the first and second pumping chamber surfaces in a direction normal to the pumping direction minus the distance between the sides of the diaphragm first and second layers adjacent the pumping chamber surfaces,    wherein the length of the pumping chamber in the pumping direction is greater than or equal to one wavelength of said sinusoidally shaped diaphragm and said motion inducing means is, at least in the region of the diaphragm adjacent the first and second pumping chamber surfaces, disposed within the first and second layers of the diaphragm.    
     
     
         2 . The pump claimed in  claim 1 , wherein the motion inducing means includes at least one rotatable shaft extending in the pumping direction with a helical section in the region of the first and second pumping chamber surfaces, the helical section being disposed between the first and second layers of the diaphragm, the periphery of the helical section travelling along a circular path about its rotational axis.  
     
     
         3 . The pump claimed in  claim 1  or  2 , wherein the motion inducing means includes two said rotatable shafts extending in the pumping direction, said shafts being spaced apart in said diaphragm and arranged for synchronous rotation relative to one another.  
     
     
         4 . The pump claimed in any one of the preceding claims, further including two opposed pump casing halves each having a recess therein respectively defining one of said two said pumping chamber surfaces.  
     
     
         5 . The pump claimed in  claim 4 , wherein, when viewed in the pumping direction, the recesses are of a curved concave shape.  
     
     
         6 . The pump claimed in  claim 5 , wherein said diaphragm includes longitudinal edges that extend in the pumping direction and the diaphragm is sealingly clamped between said casing halves along said edges.  
     
     
         7 . The pump claimed in any one of  claims 1  to  4 , wherein, when viewed in the pumping direction, the recesses are of a concave substantially rectangular shape.  
     
     
         8 . The pump claimed in  claim 7 , wherein said diaphragm includes longitudinal edges that extend in the pumping direction adapted to sealingly slide along opposed walls of the pumping chamber.  
     
     
         9 . The pump as claimed in any one of the preceding claims, further including at least one resilient axial beam within said diaphragm extending in a direction parallel to said pumping direction, said axial beam(s) compressed along its/their length(s) into a substantially sinusoidal configuration and adapted to deform adjacent regions of said diaphragm to said sinusoidal configuration.  
     
     
         10 . The pump as claimed in  claim 9 , including at least one pair of said resilient axial beams within said diaphragm, one of said beams in said pair(s) disposed between the motion inducing means and said first diaphragm layer and the other of said beams in said pair(s) disposed between the motion inducing means and said second diaphragm layer.  
     
     
         11 . The pump as claimed in any one of the preceding claims, further including at least one resilient lateral beam within said diaphragm extending in a direction normal to said pumping direction, said lateral beam(s) biased to a substantially flat configuration and adapted to deform adjacent regions of said diaphragm to a curved configuration replicating an adjacent said pumping chamber surface when the beam(s) is/are driven towards said pumping chamber surface by said motion inducing means.  
     
     
         12 . The pump as claimed in  claim 11 , further including a plurality of said lateral beams disposed in a parallel and spaced apart relationship between said pump inlet and outlet.  
     
     
         13 . The pump as claimed in any one of the preceding claims, further including spacing means within said diaphragm adapted to maintain said first and second layers of the diaphragm a constant distance apart.  
     
     
         14 . The pump as claimed in any one of  claims 2  to  13 , further including a drive means adjacent one of the inlet or outlet and a bearing journal adjacent the other of said inlet or outlet, the drive means adapted to rotate one end of said shaft and the journal adapted to support the other end of said shaft.  
     
     
         15 . The pump as claimed in  claim 14 , wherein said drive means is adjacent the inlet and said journal is adjacent the outlet.