Pump

Abstract

A pump includes a pump housing ( 10, 11, 20 ) that has a circular-cylindrical piston chamber ( 14 ), a rotatable and axially movable circular-cylindrical pump piston ( 40 ) in said chamber, means ( 30, 43 ) for rotationally driving the piston in the chamber, and means ( 11, 41; 13, 42; 67, 68 ) for imparting to the piston guided axially reciprocating movement in the piston chamber through the medium of piston rotation, wherein the pump includes lines and valve means for permitting one-way suction and one-way propulsion of pump fluid respectively into and out of the pump chambers between the ends of the piston chamber and the respective adjacent end of the piston. The means for imparting axial reciprocating movement to the piston are adapted to cause the piston to move axially at a constant speed at a constant rotational speed of the piston, at least during the expulsion of pump fluid.

1 . A pump comprising a pump housing ( 10 ,  11 ,  20 ), that includes a circular-cylindrical piston chamber ( 14 ), a circular-cylindrical pump piston ( 40 ) which is rotatable and axially displaceable in the chamber, means ( 30 ,  43 ) for rotationally driving the piston in the chamber, and means ( 11 ,  41 ;  13 ,  42 ;  67 ,  68 ) for imparting to the piston guided axial reciprocating movement in the piston chamber through the medium of piston rotation, wherein the pump includes lines and valve means for enabling pump fluid to be sucked into and pumped out of the pump chambers in one single direction between the ends of the piston chamber and a respective closely adjacent end of the piston, characterised in that the means for imparting axial reciprocating movement to the piston are adapted to cause the piston to travel axially at a constant speed at a constant piston rotating speed, at least during delivery of pump fluid.  
     
     
         2 . A pump according to  claim 1 , characterised in that the mutually adjacent end surfaces ( 11 ,  41 ;  13 ,  42 ) of the piston and the piston chamber respectively, said adjacent end surfaces defining pump chambers ( 51 ,  52 ) with the cylindrical inner wall ( 10 ) of the piston chamber, are generally complementary so as to minimise the dead volume of said pump chambers ( 51 ,  52 ).  
     
     
         3 . A pump according to  claim 2 , characterised in that each of the end surfaces is defined by points Pn Q(n, Yn, Zn) in a three-dimensional orthogonal co-ordinate system X, Y, Z, wherein Z lies in the chamber axis and the piston axis, and wherein the end surface is tangential to the XY-plane of the system 
 Xn=a cos α   Yn=a sin α   Zn=a α h/r π   where the variable α denotes the radial distance of the point from the Z-axis, and the variable α denotes the angular distance of the point from the XZ-plane about Z    0<a≦r    −π<α≦π,    wherein    r=the radius of the piston    h=the length of piston stroke    π=constant.    
     
     
         4 . A pump according to  claim 1  or  2 , characterised in that the barrel wall of the piston ( 40 ) or of the chamber ( 14 ) includes a guide groove ( 67 ); in that the barrel wall of the chamber or of the piston ( 40 ) carries a guide pin ( 68 ) that engages in the groove ( 87 ); and in that the groove ( 67 ) is designed to cause the piston to move axially at a constant speed between its end positions at a constant rotational speed of the piston.  
     
     
         5 . A pump according to any one of claims  1 - 4 , characterised in that a drive shaft ( 30 ) co-axial with the piston extends along a channel ( 22 ,  23 ) through a housing wall ( 20 ) and has a non-round dogging part ( 32 ) which engages in a dogging opening ( 43 ) in the adjacent end of the piston ( 40 ); in that the channel ( 22 ,  23 ) has adjacent the piston a widened part which receives a longitudinal section of the non-round dogging part on the one hand and filling bodies ( 48 ) disposed on the piston on the other hand, wherein the dogging part ( 32 ) and the filling bodies ( 48 ) fill the cross-sectional area of the widened part ( 23 ).  
     
     
         6 . A pump according to any one of claims  2 - 5 , characterised in that the shaft ( 30 ) has a widened part ( 31 ) which fills an axially outer part of the widened portion ( 23 ) of the channel; in that the filling bodies ( 48 ) are terminated in a plane normal to the axis of the piston ( 40 ) and fill the remaining part of the widened portion of the channel together with the dogging part ( 32 ) when the adjacent pump chamber ( 52 ) has a minimised volume.  
     
     
         7 . A pump according to any one of claims  4 - 6 , characterised in that the piston ( 40 ) has rotationally symmetrical ends.  
     
     
         8 . A pump according to  claim 7 , characterised in that the ends of the piston and of the pump chambers are generally planar and perpendicular to the axis of the piston.  
     
     
         9 . A pump according to any one of claims  1 - 8 , characterised by an inlet port or line ( 15 ) and an outlet port or line ( 16 ) which connect through the pump chamber wall ( 10 ) in two diametrically opposed regions of the piston chamber ( 14 ) in a longitudinal centre region thereof, two diametrically opposed recesses or cavities ( 44 ,  45 ) in the longitudinal centre region of the piston, a first channel ( 46 ) in the piston between its latter recess ( 45 ) and its one end surface ( 41 ), a second channel ( 47 ) in the piston between its second recess ( 44 ) and its second end surface ( 42 ).  
     
     
         10 . A pump according to any one of claims  1 ,  2 ,  4 - 8 , characterised in that the piston is divided into two axially separated parts ( 40 ,  40 ′); in that each of said piston parts has an own device ( 67 ,  68 ;  67 ′,  68 ′) for translating rotational speed to axial movement speed; in that each piston part has a first groove ( 144 ,  144 ′) which is in contact with a fluid inlet port ( 15 ,  15 ′) and has a peripheral widening of less than 180°; in that each piston part has a second groove ( 145 ) which is in contact with an outlet port ( 16 ,  16 ′) and which has a peripheral widening of more than 180°, so that fluid will be delivered through a rotational angle of 180°; in that the guide groove ( 67 ) is adapted to cause the piston to move at a constant axial speed during the pump delivery phase at a constant speed of piston rotation; and in that the piston parts ( 40 ,  40 ′) are adapted to be rotationally driven at a constant and similar speed of rotation and are adapted for axial movement in relation to each other.