Device for Concentrating a Liquid, and Differential Piston Pump

Abstract

Disclosed is a device (V) for concentrating a liquid (F) which is pumped through a concentrating apparatus ( 3 ) by means of a differential piston pump and directly impinges the differential piston (K) in an assisting manner during the conveying stroke at a residual pressure as a concentrate (FK). The differential piston of said device (V) is driven by a drive shaft ( 12 ) that actuates a linearly guided valve control member ( 18 ) of an intake and discharge valve assembly (A). The differential piston pump is embodied as a radial piston pump (R) in which eccentric attachments ( 13, 14 ) for the differential piston (K) and the valve control member ( 18 ) are disposed on the drive shaft ( 12 ), the differential piston (K) and the valve control member ( 18 ) being hinged directly to the eccentric attachments ( 13, 14 ) by means of traction and pressure couplings (S).

1 . A device (V) for concentrating a liquid (F) pumped by a differential piston pump through a concentrating means ( 3 ), which liquid acts, as concentrate (FK) under residual pressure, directly on the at least one differential piston (K) in such a manner as to assist the delivery stroke, the differential piston (K) being driven by a drive shaft ( 12 ) which actuates at least one linearly guided valve control member ( 18 ) of an inlet and outlet valve arrangement (A), wherein the differential piston pump is a radial piston pump (R), in that eccentrics ( 13 ,  14 ) for the differential piston (K) and the valve control member ( 18 ) are arranged on the drive shaft ( 12 ), and in that the differential piston (K) and the valve control member ( 18 ) are coupled directly to the eccentrics ( 13 ,  14 ) with push and pull couplings (S). 
   
   
       2 . A differential piston pump for liquids (F), having a housing comprising an inflow and an outflow for the liquid (F) to be pumped and an inlet ( 5 ) and an outlet ( 6 ) for liquid (FK) under residual pressure, at least one differential piston (K) delivering the liquid (F) from the inflow into the outflow, which differential piston may be driven by a drive shaft ( 12 ) and during the delivery stroke also directly by the residual pressure and separates a pump chamber from a pressure chamber ( 36 ), at least one inlet and outlet valve arrangement (A) for the pressure chamber ( 36 ), and at least one linearly guided valve control member ( 18 ), actuated by the drive shaft ( 12 ), of the inlet and outlet valve arrangement (A), wherein the differential piston pump is a radial piston pump (R), in that eccentrics ( 13 ,  14 ) for the differential piston (K) and the valve control member ( 18 ) are arranged on the drive shaft ( 12 ), and in that the differential piston (K) and the valve control member ( 18 ) are coupled directly to the eccentrics ( 13 ,  14 ) with push and pull couplings (S). 
   
   
       3 . The differential piston pump as claimed in  claim 2 , wherein a single valve control member ( 18 ) is provided for the inlet and outlet valve arrangement (A). 
   
   
       4 . The differential piston pump as claimed in  claim 2 , wherein the push and pull coupling (S) comprises a draw body ( 44 ) mounted rotatably on the eccentric ( 13 ,  14 ) and at least one engaging member ( 48 ) provided at one end of a shaft ( 15 ,  19 ) of the differential piston (K) or of the valve control member ( 15 ), and in that between the engaging member ( 48 ) and the draw body ( 44 ) there are provided a substantially radially active form-fitting engagement and, in the circumferential direction, preferably parallel to a tangent to the eccentric ( 13 ,  14 ), a slideway. 
   
   
       5 . The differential piston pump as claimed in  claim 4 , wherein the slideway provides protection against rotation for the shaft ( 15 ,  19 ). 
   
   
       6 . The differential piston pump as claimed in  claim 4 , wherein the draw body ( 44 ), which, preferably, consists of two axially assembled halves ( 44   a,    44   b ) or is in one piece, comprises for the shaft ( 15 ,  19 ) an externally open pocket ( 45 ) undercut in the slideway, whose internal width, when viewed in the axial direction, is less than the external width of the shaft ( 15 ,  19 ). 
   
   
       7 . The differential piston pump as claimed in  claim 6 , wherein the shaft ( 15 ,  19 ) of the differential piston (E) and/or of the valve control member ( 18 ) is arranged in a slide guide ( 37 ) fixed to the housing, in that the slide guide ( 37 ) comprises a sliding bushing ( 41 ), and in that the sliding bushing ( 41 ) engages with formed-on supporting shells ( 42 ), oriented towards one another in the direction of rotation of the eccentric ( 13 ,  14 ), with a sliding fit between side walls of the pocket ( 45 ). 
   
   
       8 . The differential piston pump as claimed in  claim 6 , wherein the draw body ( 44 ) is positioned axially on the eccentric ( 13 ,  14 ) via the slideway and/or the supporting shells ( 42 ). 
   
   
       9 . The differential piston pump as claimed in  claim 6 , wherein a bottom of the pocket forms a pressure surface ( 49 ) for the shaft end, which surface is longer than the external width of the shaft end, in that, at a distance from the shaft end, two diametrically opposing parallel grooves ( 45 ) or a circumferential groove are formed in the shaft, which grooves define a width approximately corresponding to the internal width of the pocket ( 45 ), and in that the shaft end adjoining the grooves or groove forms as engaging member ( 48 ) at least one externally protruding driver, which engages in an undercut ( 46 ) formed in a pocket side wall. 
   
   
       10 . The differential piston pump as claimed in  claim 9 , wherein the undercut ( 46 ) extends parallel to a tangent to the eccentric ( 13 ,  14 ) and is longer in this direction than the driver. 
   
   
       11 . The differential piston pump as claimed in  claim 2 , wherein the eccentric ( 14 ) for the valve control member ( 18 ) of the outlet and inlet valve arrangement (A) assigned to a differential piston (K) is offset relative to the eccentric ( 13 ) for this differential piston (K) by approximately 90° about the axis ( 38 ) of the drive shaft ( 12 ) and in a leading manner in the driving direction of rotation ( 40 ). 
   
   
       12 . The differential piston pump as claimed in  claim 2 , wherein three or more differential pistons (K) are distributed in a stellate arrangement in the axis ( 38 ) of the drive shaft ( 12 ), and in that a common eccentric ( 13 ) and a common draw body ( 44 ) are assigned to the differential pistons (K). 
   
   
       13 . The differential piston pump as claimed in  claim 12 , wherein the valve control members ( 18 ) for the outlet and inlet valve arrangements (A) of the differential pistons (K) are distributed regularly in a stellate arrangement about the axis ( 38 ) of the drive shaft ( 12 ), preferably with a respective offset of approximately 90° relative to the differential pistons (K), and in that a common eccentric ( 14 ) and a common draw body ( 44 ) are assigned to the valve control members ( 18 ). 
   
   
       14 . The differential piston pump as claimed in  claim 2 , wherein the outlet and inlet valve arrangement (A) comprise, fixed to the housing, an inlet valve seat ( 27 ) and an outlet valve seat ( 28 ), which are oriented radially relative to the axis ( 38 ) of the drive shaft ( 12 ) and are coaxial, in that the outlet valve seat ( 28 ) is positioned closer to the drive shaft ( 12 ) than the inlet valve seat ( 27 ), and in that the outlet valve seat ( 28 ) points towards the drive shaft ( 12 ) and the inlet valve seat ( 27 ) points away from the drive shaft ( 12 ). 
   
   
       15 . The differential piston pump as claimed in  claim 14 , wherein the valve control member ( 18 ) extends in each case with radial spacing through the outlet valve seat ( 28 ) as far as into the inlet valve seat ( 27 ), is sealed relative to the drive shaft ( 12 ) and between the valve seats ( 27 ,  28 ), and comprises a first shoulder ( 23 ) for lifting an outlet valve body arranged movably on the side of the outlet valve seat ( 28 ) pointing towards the drive shaft ( 12 ) and a second shoulder ( 24 ) for lifting an inlet valve body arranged movably on the side of the inlet valve seat pointing away from the drive shaft ( 12 ). 
   
   
       16 . The differential piston pump as claimed in  claim 15 , wherein the shoulders ( 23 ,  24 ) are formed by the ends of a tube ( 22 ) fixed, preferably screwed, to the valve control member ( 18 ). 
   
   
       17 . The differential piston pump as claimed in  claim 15 , wherein the inlet valve body ( 32 ) is a disk loaded by a spring ( 33 ) towards the inlet valve seat ( 27 ), preferably centered by the spring ( 33 ), and in that the outlet valve body ( 29 ) is an annular disk loaded by a spring ( 31 ) towards the outlet valve seat ( 28 ) and guided movably on the valve control member ( 18 ), preferably with a sliding ring seal ( 30 ) arranged between the valve control member ( 18 ) and the annular disk. 
   
   
       18 . The differential piston pump as claimed in  claim 17 , wherein the annular disk and the disk comprise conical or spherical seat surfaces, and, preferably, the valve seats ( 27 ,  28 ) are of conical or spherical construction. 
   
   
       19 . The differential piston pump as claimed in  claim 15 , wherein the distance, when viewed in the longitudinal direction of the valve control member ( 18 ), between the shoulders ( 23 ,  24 ) is smaller than the distance between the valve bodies positioned on the valve seats ( 27 ,  28 ), preferably in such a way that, at the top and bottom dead centers of the differential piston (K) assigned to the outlet and inlet valve arrangement (A), both valve bodies are seated and play is present relative to the respective shoulder ( 23 ,  24 ), preferably in each case of approx. 0.1 to 0.4 mm. 
   
   
       20 . The differential piston pump as claimed in  claim 15 , wherein the valve control member ( 18 ) extends between the outlet valve seat ( 28 ) and the drive shaft ( 12 ) and between the valve seats ( 27 ,  28 ) through guides ( 21 ,  37 ) fixed to the housing. 
   
   
       21 . The differential piston pump as claimed in  claim 14 , wherein the valve seats ( 27 ,  28 ) and the one guide ( 21 ) are arranged in sleeve members ( 25 ,  26 ), which are mounted in a housing chamber between a housing wall ( 10 ) adjacent to the drive shaft ( 12 ) and a housing cover ( 9 ) and comprise an inlet ( 5 ) and two outlets ( 34 ,  6 ), and in that a further inlet is arranged in the housing wall ( 10 ). 
   
   
       22 . The differential piston pump as claimed in  claim 1 , wherein the eccentric ( 13 ) for the differential piston (K) and the eccentric ( 14 ) for the valve control member are constructed with at least substantially identical dimensions and with identical eccentricities (C). 
   
   
       23 . The differential piston pump as claimed in  claim 1 , wherein the extent of the eccentricity (C) of the eccentric ( 13 ,  14 ) is adjustable and/or the eccentric ( 13 ,  14 ) is arranged replaceably on the drive shaft.