Multi-stage centrifugal pump (axial face seal)
An axial face seal ( 13 ), which seals a pump housing in the region of the pump shaft ( 12 ), is constructed in an axially compact manner. Spring holders ( 24, 25 ), which transmit the required pressing force of a compression spring ( 23 ), are connected to one another with a positive fit in a rotation direction, and hold a rotating axial face seal ring ( 19 ) in a rotationally fixed manner to the pump shaft ( 12 ). The spring holders ( 24, 25 ) are compact and enclose an abutment ring ( 33 ) for pump impellers as well as the compression spring ( 23 ). A motor-side spring ( 24 ) engages over the rotating axial face seal ring ( 19 ), by which an axially extremely short constructional length is achieved.
1. A multi-stage centrifugal pump comprising a pump housing ( 3 ); a pump shaft ( 12 ) rotatably mounted in the pump housing, a motor-side end of the pump comprising at least one cylindrical shaft section ( 21 ) and a splined shaft section ( 22 ) connecting thereto; at least two impellers ( 8 ) arranged in a rotationally fixed manner on the splined shaft section the impellers being clamped between an abutment ring ( 33 ) seated on the pump shaft ( 12 ) and a free end of the pump shaft; and an axial face seal ( 13 ) incorporated between the cylindrical shaft section ( 21 ) and the pump housing ( 3 ), wherein the axial face seal ( 13 ) comprises a stationary axial face seal ring ( 14 ) arranged in the pump housing ( 3 ) sealed with respect to the pump housing, and a rotating axial face seal ring ( 19 ) arranged on the pump shaft ( 12 ) and sealed with respect to the pump shaft ( 12 ), said stationary axial face sealing ring and said rotating axial sealing ring ( 14 , 19 ) comprising respective axial sealing surfaces ( 17 , 18 ) which slide on one another and are impinged to one another by way of a spring force exerted by compression spring means ( 23 ) arranged between two spring holders ( 24 , 25 ), and wherein the abutment ring ( 33 ) is arranged in a transition region ( 34 ) of the pump shaft ( 12 ) between the cylindrical shaft section ( 21 ) and the splined shaft section ( 22 ) as well as between the two spring holders ( 24 , 25 ), wherein positive-fit means ( 26 , 30 ) are provided between the spring holders ( 24 , 25 ), which are effective at least in a working rotation direction ( 32 ) of the pump shaft ( 12 ).
2. The centrifugal pump according to claim 1 , wherein the abutment ring ( 33 ) is held on the pump shaft ( 12 ) with a positive fit at least in the axial direction toward a motor-side end of the pump shaft.
3. The centrifugal pump according to claim 1 , wherein the cylindrical shaft section ( 21 ) has a larger diameter than the splined shaft section ( 22 ) in a groove base, and the diameter of the cylindrical shaft section is equal or larger than the diameter of the splined shaft section ( 22 ) in the remaining region thereof.
4. The centrifugal pump according to claim 1 , wherein the abutment ring ( 33 ) on an inner side thereof is designed for positive-fit engagement into a splined shaft profile of the splined shaft section ( 22 ).
5. The centrifugal pump according to claim 1 , wherein the abutment ring ( 33 ) comprises oblique surfaces ( 35 ) on an inner side thereof, which are supported on at least one corresponding oblique surface of the pump shaft ( 12 ) in the transition region ( 34 ) of the pump shaft ( 12 ) between the cylindrical shaft section ( 21 ) and the splined shaft section ( 22 ).
6. The centrifugal pump according to claim 1 , wherein the spring means ( 23 ) at least partly engage over the abutment ring ( 33 ) and the rotating axial face seal ring ( 19 ).
7. The centrifugal pump according to claim 1 , wherein the spring means are formed by a helical compression spring ( 23 ).
8. The centrifugal pump according to claim 1 , wherein the spring holders ( 24 , 25 ) comprise positive-fit means ( 26 , 31 ), with which they are axially fixed to one another at least in one direction under bias of the spring means ( 23 ), for the purpose of assembly.
9. The centrifugal pump according to claim 1 , wherein the spring holders ( 24 , 25 ) are bayoneted to one another in a manner such that locking is effected opposite to the working rotation direction ( 32 ).
10. The centrifugal pump according to claim 1 , wherein a motor-side spring holder ( 24 ) of the spring holders ( 24 , 25 ) on an axial face seal ring side is designed in an angulated manner such that the spring means ( 23 ) surrounds the rotating axial face seal ring ( 19 ).
11. The centrifugal pump according claim 1 , wherein an impeller-side spring holder ( 25 ) of the spring holders ( 24 , 25 ) comprises at least one catch which engages into a splined shaft profile of the splined shaft section with a positive fit and which connects the impeller-side spring holder ( 25 ) to the pump shaft ( 12 ) in a rotationally fixed manner.
12. The centrifugal pump according to claim 1 , wherein the stationary axial face seal ring ( 14 ) comprises positive fit means ( 16 ) on an outer periphery thereof, with which the stationary axial face seal ring is secured against rotation in the pump housing ( 3 ).
13. The centrifugal pump according to claim 1 , wherein an impeller-side spring holder ( 25 ) of the spring holders ( 24 , 25 ) comprises recesses ( 29 ) in a peripheral wall ( 28 ) thereof which is open toward a motor-side spring holder ( 24 ) of the spring holders ( 24 , 25 ) on an axial face seal ring side and into which radial projections ( 26 ) of the motor-side spring holder ( 24 ) on the axial face seal ring side engage.
14. the centrifugal pump according to claim 13 , wherein edges of the recesses ( 29 ) are designed in a reinforced manner in an engagement region of the projections ( 26 ) by an enlargement of bearing surfaces ( 30 ).