Patent ID: 8038419

Claim:
A controllable coolant pump comprising: (a) a pump housing comprising a plurality of bores, a plurality of piston guides disposed in the bores, a plurality of spring chambers disposed between the bores, and a plurality of seal accommodations; (b) a driven shaft mounted in the pump housing, said shaft having a free, flow-side end; (c) an impeller wheel disposed on said free, flow-side end so as to rotate with said shaft, said impeller wheel having an outflow region; (d) a pressure-activated annular valve slide having an outer cylinder variably covering the outflow region of the impeller wheel; and (e) a plurality of piston rods disposed on the valve slide and mounted in the piston guides so as to be axially displaceable; wherein the bores are uniformly distributed circumferentially in the pump housing parallel to the shaft and associated with the piston rods disposed on the valve slide, each bore having a first end toward the valve slide and a second end opposite to the first end; wherein the seal accommodations are situated in the pump housing at the first end and a plurality of rod seals are disposed in the seal accommodations; wherein an annular groove is disposed in the pump housing at the second end, said annular groove connecting the bores with each other; wherein an annular piston mounted to be displaceable in the annular groove connects the piston rods with each other at piston rod ends of the piston rods towards the annular groove; wherein a plurality of chamber pressure springs are disposed in the spring chambers and braced against the annular piston in a uniform distribution circumferentially over the annular piston; wherein an annular crosspiece is disposed on a top side of the annular piston opposite to the piston rods and a rolled folded covering is fastened to the annular crosspiece via a clamping lid braced against the pump housing via bracing elements; wherein at least one pressure connector bore for pressure activation of the valve slide is disposed in the pump housing, said at least one bore opening into a pressure connector fitting disposed on the pump housing; and wherein an elastomer bypass seal is disposed on an outer edge of the valve slide, said elastomer bypass seal in a closed position closing an annular gap between the pump housing and the valve slide when the valve slide is brought into contact with a sealing surface of the pump housing.