High pressure rotary centrifugal separator having apparatus for automatically cyclically reciprocating a corotating separator basket scraper

In a centrifugal separator having a fluid pressure reciprocated piston assembly including a housing having a piston chamber therein with a rod opening at one end, a piston including a piston head reciprocable within said piston chamber and hydraulically dividing said piston chamber into a head end and a rod end and a piston rod fixedly secured to said head and slidably projecting through said rod opening, a source of hydraulic fluid under a constant pressure, and control means for controlling the flow of fluid between said source, said piston chamber and a vent to drive said piston and rod in cyclic reciprocation relative to said housing;

• the improvement wherein said control means comprises inlet passage means constantly connecting said rod end of said piston chamber to said source to constantly bias said piston toward said head end of said piston chamber, means defining an axially extending valve chamber in said piston, said valve chamber having a first section of a first diameter at one end and a second section of a larger diameter at its other end, a valve member having first and second lands thereon respectively slidably received in said first and second sections of said valve chamber and defining a first annular chamber therebetween, said first land being located at one end of said valve member, a valve stem extending from said second land to the other end of said valve member and slidably received in a stem receiving opening at said other end of said valve chamber and defining a second annular chamber between said second land and said other end of said valve chamber, means defining an axial passage through said valve member, first port means in said piston establishing constant fluid communication between said rod end of said piston chamber and said first annular chamber, second port means in said piston operable when said piston is at said head end of said piston chamber to place said second annular chamber in communication with said rod end of said piston chamber to drive said valve member to said one end of said valve chamber, third port means in said piston operable when said valve member is at said one end of said valve chamber to place said head end of said piston chamber in communication with said rod end thereof via said first annular chamber to drive said piston away from the head end of said piston chamber, movement of said piston away from said head end closing said second port means to trap fluid under pressure in said second annular chamber, first vent passage means in said piston and said housing operable to vent fluid under pressure from said second annular chamber when said piston has moved a predetermined distance from said head end, to thereby permit said valve member to move away from said one end of said valve chamber, movement of said valve member away from said one end of said valve chamber insolating said third port means from said rod end of said piston chamber and establishing communication between said head end and said axial passage through said valve member, and second vent passage means in said piston and said housing in constant communication with said axial passage.

In a centrifugal separator assembly or the like wherein a basket scraper element is mounted upon a rotary shaft means to be rotatively driven by said shaft means and axially reciprocated relative to it, and means is provided for rotating said shaft means;

• the improvement wherein said rotary shaft means has a first piston chamber closed at one end and a bore extending from the other end of said first chamber, said first chamber having an internal diameter greater than that of said bore, a piston having a head section sealingly slidably received in said first chamber and a rod section sealingly slidably received in said bore, said piston being axially reciprocable within said shaft means between a first end limit wherein said head section is adjacent said closed end of said first chamber and a second end limit wherein said head section is adjacent said other end of said first chamber, said piston including axially spaced radial surfaces of differential area, a valve chamber, and a vent passage connecting with said valve chamber, a source of hydraulic fluid under pressure, inlet passage means in said shaft means for conducting fluid under pressure from said source to one of said surfaces to constantly bias said piston in one axial direction, a pilot valve slidably mounted within said valve chamber within said piston for reciprocatory movement within said piston between first and second end limits, said valve having axially spaced radial surfaces of differential area, first passage means in said piston and said valve operable when said valve is at its first end limit to conduct fluid under pressure through said head section to said closed end of said first chamber to drive said piston to its second end limit, second passage means in said piston and said valve operable when said piston is at its first end limit to conduct fluid under pressure from said inlet passage means to a portion of said main valve chamber adjacent one of said valve surfaces to bias said valve to its first end limit, a radial valve vent passage means in said shaft means communicatable with said vent passage in the piston when the piston has moved axially to radially aligned position with it for venting said portion of said main valve chamber substantially upon arrival of said piston at its second end limit to allow said valve to move to its second end limit, and a second vent passage in said shaft means operable when said valve is at its second end limit for venting one end of said first chamber to allow the bias of fluid under pressure to restore said piston.

In a centrifugal separator or the like wherein an element mounted upon a rotary shaft means is driven by said shaft means simultaneously both in rotation and axial reciprocation, said apparatus including means defining a piston chamber within said shaft means, piston means including a piston head slidably received within said piston chamber for reciprocatory movement between opposite end limits of movement within said piston chamber, said piston head dividing said piston chamber into a rod end chamber and a head end chamber, a source of fluid pressure, and valve means for conducting fluid pressure from said source to and from said piston chamber to drive said piston means in cyclically repeated reciprocation, said valve means including means defining a valve chamber within said piston means and a valve member slidably received within said valve chamber for reciprocatory movement between opposite end limits of movement;

• the improvement comprising axially spaced first and second land means on said valve member defining a first chamber therebetween and second and third chambers at the sides of said respective land means remote from said first chamber, first passage means continuously connecting said source to said rod end of said chamber and to said first chamber to bias said piston head toward one of its end limits of movement within said piston chamber and continuously connecting said source to said first chamber to continuously bias said valve member toward one of its end limits of movement within said valve chamber, first port means for connecting said source to said third chamber when said head is at said one end limit of movement to overcome the bias exerted on said valve member via said first means to thereby drive said valve member to said other of its end limits of movement within said valve chamber, said valve member when located at said other of said end limits connecting said source to said head end of said piston chamber to drive said head to said other of its end limits of movement within said valve chamber, second port means for venting said third chamber upon the arrival of said head at said other of its end limits to thereby permit said valve member to be biased to its one end limit of movement within said valve chamber, and means in said valve member for venting the head end of said piston chamber when said valve member arrives at its one end limit to thereby permit said head to be biased back to its one end limit.