Self cleaning centrifuge drum with a piston valve defining one side of the sludge chamber

Claim 1

In a centrifugal separator constructed for intermittent discharge of sludge, comprising: a. a rotatably mounted separator drum having an upper end member and a lower end member, at least one sludge discharge passageway disposed at the radially outward periphery thereof, a distributor disposed centrally within the drum, and a sludge chamber disposed outwardly of the distributor, b. one of said end members being a valve piston closure movable vertically to open and close the sludge discharge passageway for desludging, said valve piston closure defining one end of the sludge chamber, c. a closing chamber disposed outwardly of the piston closure member extending from adjacent the axis of the drum to adjacent the radially outward periphery thereof, defined in part by the axially outerward side of the piston closure member, for receiving and discharging fluid for, respectively, forcing the piston closure member to the closed position and relieving force for initiating the moving of the piston closure member to its open position under the influence of material filling the drum, d. means for supplying fluid to the closing chamber and means for discharging fluid therefrom, the improvement which comprises: e. a cap having a radially outwardly disposed portion, mounted in the drum covering at least a portion of the valve piston closure on the axially inwardly disposed side thereof, and on the radially inwardly disposed sid of the sludge chamber, the valve piston closure being in sliding, sealing relation with a radially outwardly disposed portion of the cap, said cap defining with the covered portion of the valve piston closure an opening chamber for receiving and holding fluid for assisting the positioning of the valve piston closure into the open position when material filling the drum recedes outwardly after the movement of the valve piston is initiated by discharging the fluid from the closing chamber, and f. means for supplying fluid to the opening chamber for said holding of fluid thereby.