초록 ▼

A centrifugal pump with a mechanical seal cartridge is disclosed. The pump has a pump casing, a rotatable drive shaft extending into the casing from the rear side, and an open impeller mounted on the drive shaft, this impeller having radially extending vanes with leading and trailing edges. The sea

A centrifugal pump with a mechanical seal cartridge is disclosed. The pump has a pump casing, a rotatable drive shaft extending into the casing from the rear side, and an open impeller mounted on the drive shaft, this impeller having radially extending vanes with leading and trailing edges. The seal cartridge is mounted in a back plate structure of the casing so as to seal a central seal chamber formed by the back plate structure and extending around the drive shaft. This seal chamber has a circumferential wall extending around at least a forward portion of the seal mechanism and spaced therefrom so as to form an open annular space for circulation of fluid which lubricates and cools the mechanical seal.

대표청구항 ▼

The invention claimed is: 1. A centrifugal chopper pump capable of pumping a fluid containing said solid material, said pump comprising: a pump casing having a frontal intake port, a pump outlet in a side thereof and back plate structure forming a central seal chamber extending rearwardly from a ce

The invention claimed is: 1. A centrifugal chopper pump capable of pumping a fluid containing said solid material, said pump comprising: a pump casing having a frontal intake port, a pump outlet in a side thereof and back plate structure forming a central seal chamber extending rearwardly from a central opening formed in a radially extending wall of said back plate structure; a drive shaft extending into said casing and through said central opening from a rear side of said casing, said drive shaft being rotatable about an axis of rotation in a selected direction of rotation; an open impeller mounted on said drive shaft for rotation therewith, said impeller having radially extending vanes each having a leading edge that extends generally radially in relation to said axis of rotation and each having a trailing edge with a substantially open, circumferentially extending gap between adjacent trailing edges of these vanes; at least one cutter mounted in said pump casing, and located in said input port, the leading edges of said vanes rotating closely past said at least one cutter during operation of the pump in order to cut up incoming solid material; and a mechanical seal mechanism comprising a seal cartridge mounted in said seal chamber, said seal mechanism having a rotating component mounted on said drive shaft and a stationary component mounted on said back plate structure, said rotating component including a central sleeve adapted to and sized to be mounted on said drive shaft for rotation therewith, a seal support mounted on said sleeve for rotation therewith and an annular first seat mounted on the seal support, said stationary component comprising an annular flange member having a radially inwardly extending flange, an annular seat housing, an annular second seat mounted on said seat housing adjacent said first seat, and a spring extending between said seat housing and said flange on said flange member and pressing said second seat against said first seat in order to provide a mechanical seal by maintaining a closing pressure sufficient to keep adjacent faces of the first and second seats together, said seal chamber having a circumferentially extending wall extending around at least a forward portion of said seal mechanism and spaced therefrom so as to form an open annular space exposed to the pumped fluid for circulation of a portion of said fluid, wherein during operation of said pump, said seal mechanism effectively seals an annular gap between said drive shaft and said back plate structure while being lubricated and cooled by said portion of said fluid being pumped by the chopper pump. 2. A centrifugal chopper pump according to claim 1 wherein the circumferentially extending wall of said seal chamber converges in a front to rear axial direction. 3. A centrifugal chopper pump according to claim 1 wherein the circumferentially extending wall of said seal chamber converges in a front to rear axial direction and terminates adjacent an annular forward facing shoulder, said stationary component being fixedly connected to said back plate structure at said shoulder. 4. A centrifugal chopper pump according to claim 1 wherein said spring is a coil spring extending around said central sleeve and enclosed by said flange member and said annular seat housing. 5. A centrifugal chopper pump according to claim 4 wherein a cylindrical section of said annular seat housing extends into said flange member in a telescoping manner and an O-ring seal is mounted between said cylindrical section and the flange member is order to seal a joint between said cylindrical section and the flange member. 6. A centrifugal chopper pump according to claim 1 wherein said mechanical seal mechanism is hydraulically balanced. 7. A centrifugal chopper pump according to claim 1 wherein said impeller has a central hub into which said drive shaft extends and from which said vanes extend radially outwardly and wherein one end of said seal mechanism formed by said rotating component is located adjacent a rear end of said hub. 8. A centrifugal chopper pump according to claim 1 wherein said mechanical seal mechanism does not require external clean water flushing and does not require secondary lubrication or cooling other than said lubrication and cooling provided by the pumped fluid. 9. A centrifugal pump capable of pumping a fluid, said pump comprising: a centrifugal pump casing having an intake plate forming an intake port, a pump outlet, and a back section forming a seal chamber extending rearwardly from a central opening formed in a radially extending wall of the back section; a drive shaft extending into said casing and through said central opening from a rear side of said casing, said drive shaft being rotatable about an axis of rotation in a selected direction of rotation; an open impeller mounted on said drive shaft for rotation therewith, said impeller having radially extending vanes each having a leading edge that extends generally radially in relation to said axis of rotation and each having a trailing edge with a substantially open, circumferentially extending gap between adjacent trailing edges of these vanes; and a mechanical seal mechanism comprising a seal cartridge mounted in said seal chamber, said seal mechanism having a rotating component mounted on said drive shaft and a stationary component mounted on said back section, said rotating component including a central sleeve adapted to and sized to be mounted on said drive shaft for rotation therewith, a seal support mounted on said sleeve for rotation therewith, and an annular first seat mounted on said seal support, said stationary component comprising an annular flange member having a radially extending flange, an annular seat housing, an annular second seat mounted on said seat housing adjacent said first seat, and a spring extending between said seat housing and said flange on said flange member and pressing said second seat against said first seat in order to provide a mechanical seal by maintaining a closing pressure sufficient to keep adjacent faces of the first and second seats together, said seal chamber having a circumferentially extending wall extending around at least a forward portion of said seal mechanism and spaced therefrom so as to form an open annular space exposed to the pump fluid for circulation of a portion of said fluid, said circumferentially extending wall converging in a front to rear axial direction, wherein during operation of said pump, said seal mechanism effectively seals an annular gap between said drive shaft and said back section while being lubricated and cooled by said portion of said fluid being pumped by the pump. 10. A centrifugal pump according to claim 9 wherein a cylindrical section of said annular seat housing extends into said flange member in a telescoping manner and an O-ring seal is mounted between said cylindrical section and the flange member is order to seal a joint between said cylindrical section and the flange member. 11. A centrifugal pump according to claim 9 wherein said mechanical seal does not require external clean water flushing and does not require secondary lubrication or cooling other than said lubrication and cooling provided by the pumped fluid. 12. A centrifugal chopper pump capable of pumping a fluid containing a solid material, said pump comprising: a pump casing having a frontal intake port, a pump outlet in a side thereof, and a back plate structure forming a central seal chamber extending rearwardly from an open front end of the chamber; a rotatable drive shaft extending into said casing and through the seal chamber from a rear side of said casing, said drive shaft being rotatable about an axis of rotation in a selected direction of rotation; an open impeller mounted on said drive shaft for rotation therewith, said impeller having radially extending vanes each having a leading edge that extends generally radially in relation to said axis of rotation and each having a trailing edge with a substantially open, circumferentially extending gap between adjacent trailing edges of the vanes; a cutting mechanism mounted in said pump casing and co-operating with said impeller during use of said pump to cut up incoming solid material; and a mechanical seal cartridge mounted in said back plate structure and on said drive shaft so as to close and seal an annular gap between said drive shaft and said back plate structure while leaving open a front portion of said seal chamber which is exposed to the pump fluid so that the seal cartridge is lubricated and cooled by a portion of said fluid circulating in said front portion during use of the chopper pump, said seal cartridge including an inner sleeve mounted on said drive shaft, rotatable and stationary seats, a coil spring mounted on and extending around said inner sleeve and mounted so as to press said stationary seat against said rotatable seat, and an annular shroud arrangement covering the circumferential exterior of said coil spring so that said solid material is kept substantially away from contact with said spring. 13. A pump according to claim 12 wherein said shroud arrangement includes a stationary, annular flange member having a radially inwardly extending flange and an annular seat housing on which said stationary seat is mounted, said seat housing having a cylindrical portion telescoping into said flange member and an annular shoulder extending around its interior, and wherein said spring extends between said flange and said shoulder and biases said seat housing and said stationary seat in an axial direction away from said flange. 14. A pump according to claim 13 wherein an O-ring seal is mounted in an internal groove formed in said flange member and acts to seal a joint between said cylindrical portion of said seat housing and a cylindrical inner surface of said flange member. 15. A pump according to claim 14 wherein said flange member also has an outer flange which extends radially outwardly, is spaced forwardly from the inwardly extending flange, and has apertures through which threaded fasteners extend, and wherein said fasteners detachably secure said seal cartridge to said back plate structure and in said seal chamber. 16. A pump according to claim 14 wherein said inner sleeve is formed with an end flange projecting radially inwardly at one end of said sleeve closest to the impeller, said end flange properly locating said seal cartridge on said drive shaft by engaging an annular shoulder formed on the drive shaft. 17. A pump according to claim 12 wherein said front portion of said seal chamber is formed by a circumferentially extending wall which converges in a front to rear axial direction of the pump and a substantial annular space is provided between said seal cartridge and at least most of the axial length of said wall. 18. A pump according to claim 13 wherein said seal cartridge is installed in said pump so as to be hydraulically balanced when said pump is being used. 19. A pump according to claim 13 wherein said impeller has a central hub from which said vanes extend and said hub is mounted on said drive shaft so that a rear end of said hub is adjacent a front end of the seal cartridge.