Dosing pump

Abstract

The invention provides a metering pump having pistons ( 13, 13 ′) which lie opposite one another, are guided in cylinders ( 11, 11′ ) and are connected to one another by a slide ( 14 ) which is moved in a reciprocating manner by a drive motor ( 201 ), a switching device ( 3 ) being arranged between the pistons ( 13, 13 ′) in a valve block ( 2 ), which switching device alternately connects the opposite cylinder spaces to a suction opening ( 4 ) and a delivery opening ( 5 ).

1 . A metering pump having pistons ( 13 ,  13 ′) which lie opposite one another, are guided in cylinders ( 11 ,  11 ′) and are connected to one another by a slide ( 14 ) which is moved in a reciprocating manner by a drive motor ( 201 ), a switching device ( 3 ) being arranged between the pistons ( 13 ,  13 ′) in a valve block ( 2 ), which switching device alternately connects the opposite cylinder spaces to a suction opening ( 4 ) and a delivery opening ( 5 ).  
     
     
         2 . The metering pump as claimed in  claim 1 , in which the switching device is designed as a control cock ( 3 ) which can rotate in the valve block ( 2 ) and is provided on the circumference with grooves ( 6 ,  7 ) which are separated from one another by webs ( 8 ,  8 ′) at diametrically opposite locations, one groove ( 6 ) being in communication with a cylinder bore ( 9 ) in the valve block ( 2 ) and the other groove ( 7 ) being in communication with a cylinder bore ( 10 ) formed on the opposite side in the valve block, and the one groove coming into communication with the suction opening ( 4 ) formed in the valve block as a result of the reciprocating pivoting of the control cock ( 3 ) while the other groove is connected to the delivery opening ( 5 ) formed in the valve block, and vice versa.  
     
     
         3 . The metering pump as claimed in  claim 2 , in which the control cock ( 3 ) is of conical design and is inserted into a correspondingly conical bore in the valve block ( 2 ).  
     
     
         4 . The metering pump as claimed in  claim 2 , in which further grooves ( 6 ′,  7 ′;  6 ″,  7 ″), which are in communication with corresponding cylinder bores ( 9 ′,  9 ″,  10 ′,  10 ″) and suction and delivery openings in the valve block, are formed next to one another in the axial direction on the circumference of the control cock ( 3 ).  
     
     
         5 . The metering pump as claimed in  claim 2 , in which stops ( 17 ,  17 ′) which are spaced apart from one another are provided on the slide ( 14 ), which stops, in the region of the limit positions of the pistons, act on a lever ( 18 ) arranged on the control cock ( 3 ) in order to switch over the control cock.  
     
     
         6 . The metering pump as claimed in  claim 5 , in which a snap-action device ( 19 ,  20 ), which pivots the control cock ( 3 ) at an accelerated rate when a stop ( 17 ) bears against the lever ( 18 ), is formed on the lever ( 18 ).  
     
     
         7 . The metering pump as claimed in  claim 1 , in which the switching device is formed by nonreturn valves ( 50 ) in the valve block ( 2 ), these nonreturn valves being connected to the suction opening ( 4 ) and the delivery opening ( 5 ) via bores ( 51 ,  52 ) which are formed transversely with respect to cylinder bores ( 9 ,  10 ) in the valve block ( 2 ), the cylinder spaces of the opposite pistons ( 13 ,  13 ′) opening out into these bores ( 51 ,  52 ).  
     
     
         8 . The metering pump as claimed in  claim 7 , in which the diameter of the bores ( 51 ,  52 ) in the valve block ( 2 ) is designed to be slightly larger than the diameter of the cylinder bores ( 9 ,  10 ).  
     
     
         9 . The metering pump as claimed in  claim 7 , in which the valve block ( 2 ) is composed of elements ( 2 ′,  2 ″) in plate form which are clamped between two outer clamping plates ( 53 ).  
     
     
         10 . The metering pump as claimed in the preceding claims, in which the cylinders are formed by cylinder tubes ( 11 ,  11 ′) which at the end sides are held by a clamping element ( 35 ) so as to bear against the valve block ( 2 ).  
     
     
         11 . The metering pump as claimed in the preceding claims, in which a plurality of cylinder tubes ( 11 ,  11 ′) are arranged adjacent to one another on the valve block ( 2 ), and a corresponding number of pistons ( 13 ,  13 ′) are arranged next to one another on the slide ( 14 ).  
     
     
         12 . The metering pump as claimed in  claim 11 , in which the cylinder tubes and pistons of the individual pumps have different diameters.  
     
     
         13 . The metering pump as claimed in the preceding claims, in which the valve block ( 2 ) with cylinder tubes ( 11 ) and slide ( 14 ) is arranged on a base plate ( 1 ) in order to form a pump unit ( 100 ) which is releasably connected to a block-like drive unit ( 200 ).  
     
     
         14 . The metering pump as claimed in  claim 13 , in which locating pins ( 231 ), which engage in locating bores ( 41 ) at the base plate ( 1 ) of the pump unit ( 100 ), protrude from the block-like drive unit ( 200 ).  
     
     
         15 . The metering pump as claimed in  claim 14 , in which at least one clamping element ( 230 ), which interacts with a corresponding engagement element ( 40 ) on the base plate ( 1 ), is arranged on the drive unit ( 200 ).  
     
     
         16 . The metering pump as claimed in  claim 13 , in which a bolt ( 205 ), which protrudes from a nut ( 204 ) in engagement with a threaded spindle ( 203 ) and engages in a bore ( 43 ) in the slide ( 14 ) at the pump unit ( 100 ), is provided at the drive unit ( 200 ).  
     
     
         17 . The metering pump as claimed in  claim 16 , in which a drive unit ( 201 ) drives the threaded spindle ( 203 ) via an intermediate gear ( 202 ) which is set without play.  
     
     
         18 . The metering pump as claimed in  claim 17 , in which the direction of rotation of the drive motor ( 201 ) can be switched over by limit switches ( 206 ,  207 ) which are actuated by the longitudinal movement of the nut ( 204 ) on the threaded spindle ( 203 ).