Magnetic drive pump

Abstract

The invention relates to a magnetic drive pump (10), comprising: a housing (12) filled at least partially with a conveyed fluid; an impeller chamber (14) enclosed by the housing (12); a pump shaft (22); an impeller (24) which is arranged in the impeller chamber (14) and on the pump shaft (22); a bearing (26) which supports the pump shaft (22) in the housing (12); a can (18) which encloses a coupling chamber (20); a rotor (50) which is arranged in the coupling chamber (20) on the pump shaft (22); a ring (16) held in the housing, which supports the bearing (26) and separates the impeller chamber (14) from the coupling chamber (20); a duct (28) formed in the ring (16) for conveying a partial flow of the conveyed fluid out of the impeller chamber (14) to the bearing (26) for the purpose of lubricating the bearing (26), wherein at least part of the conveyed fluid emerging from the bearing (26) arrives in the coupling chamber (20). The object of the invention is to improve a magnetic drive pump of this type such that safe and reliable lubrication of the bearing (26) of the pump shaft (22) over a certain time is also still ensured when the pump (10) is operating in dry-run condition, i.e. when it continues running when there is no more conveyed fluid on the suction side of the pump (10). The invention achieves this object in that the coupling chamber (20) is closed in fluid-tight manner relative to the impeller chamber (14).

Claims

1. A magnetic drive pump (10), comprising: a housing (12) filled at least partially with a conveyed fluid; an impeller chamber (14) enclosed by the housing (12); a pump shaft (22); an impeller (24) which is arranged in the impeller chamber (14) and on the pump shaft (22); a bearing (26) which supports the pump shaft (22) in the housing (12); a can (18) which encloses a coupling chamber (20); a rotor (50) which is arranged in the coupling chamber (20) and on the pump shaft (22); a ring (16) held in the housing, which supports the bearing (26) and separates the impeller chamber (14) from the coupling chamber (20); a duct (28) formed in the ring (16) for conveying a partial flow of the conveyed fluid out of the impeller chamber (14) to the bearing (26) for the purpose of lubricating the bearing (26), wherein at least part of the conveyed fluid emerging from the bearing (26) arrives in the coupling chamber (20), wherein the coupling chamber (20) is closed in fluid-tight manner such that recirculation of the conveyed fluid out of the coupling chamber (20) into the impeller chamber (14) takes place only via the bearing (26).

2. The magnetic drive pump (10) according to claim 1, wherein the can (18) is produced from a non-metallic material.

3. The magnetic drive pump (10) according to claim 1, further comprising at least one restriction element (34) which restricts the throughflow of the conveyed fluid through the duct (28).

4. The magnetic drive pump (10) according to claim 3, wherein the at least one restriction element (34) partially covers or closes the opening of the duct (28) to the impeller chamber (14).

5. The magnetic drive pump (10) according to claim 4, wherein the restriction element (34) is formed in a disc shape and is fastened to the ring (16), so that it at least partially covers the opening of the duct (28).

6. The magnetic drive pump (10) according to claim 3, wherein a ring disc (32) fastened to the ring (16) forms the at least one restriction element (34) and at the same time closes a drainage bore (30) formed on the ring (16), which bore connects the coupling chamber (20) to the impeller chamber (14).

7. The magnetic drive pump (10) according to claim 1, wherein the pump shaft (22) does not have a fluidic connection between the impeller chamber (14) and coupling chamber (20).

8. The magnetic drive pump (10) according to claim 1, wherein the pump shaft (22) is formed as a solid body.

9. The magnetic drive pump (10) according to claim 1, wherein recirculation of the conveyed fluid out of the coupling chamber (20) into the impeller chamber (14) takes place via a radial bearing gap (52) in the bearing (26).

10. The magnetic drive pump (10) according to claim 9, wherein the radial bearing gap (52) is arranged on the impeller side in the bearing (26).

11. The magnetic drive pump (10) according to claim 1, wherein lubrication grooves (54) are arranged on the coupling side in the bearing (26).

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

(1) The FIGURES show in:

(2) FIG. 1 a sectional view of a magnetic drive pump according to the invention.

(3) FIG. 1 shows a magnetic drive pump 10 according to the invention in one possible configuration. The magnetic coupling comprises a housing 12 with a ring 16. The housing 12 includes an impeller chamber 14 for receiving a conveyed fluid which is drawn in through an inlet 44 and is ejected through an outlet 46. Further, the pump 10 comprises a can 18, wherein the can 18 and the ring 16 enclose a coupling chamber 20. The ring 16 separates the coupling chamber 20 from the impeller chamber 14. The can 18 consists of a non-metallic material, so that no heat generation due to eddy currents occurs therein. A pump shaft 22 extends from the impeller chamber 14 through a central opening provided in the ring 16 into the coupling chamber 20. An impeller 24 is fastened to the pump shaft 22. At the other end of the shaft 22, a rotor 50 equipped with permanent magnets is arranged in the coupling chamber 20. For bearing the pump shaft 22, the pump 10 has a bearing 26, e.g. in the form of a plain bearing with ceramic bearing elements, which is supported by the ring 16. Further, a duct 28 for supplying a partial flow of the conveyed fluid from the impeller chamber 14 to the bearing 26 is provided in the ring 16 for the purpose of lubrication. The ring 16 comprises a drainage bore 30 which is originally provided for draining the coupling chamber 20 into the impeller chamber 14. The opening of the drainage bore 30 facing the impeller chamber 14 is closed by means of a disc-shaped element 32. As a result, according to the invention the coupling chamber 20 is closed in fluid-tight manner relative to the impeller chamber 14. In this manner, it is ensured that a sufficient quantity of conveyed fluid for lubricating the bearing 26 in dry-run condition remains in the coupling chamber 20 over a certain time. Recirculation of the conveyed fluid out of the coupling chamber 20 into the impeller chamber 14 takes place via the bearing 26. The exclusive recirculation of the conveyed fluid via the bearing 26 out of the coupling chamber 20 into the impeller chamber 14 provides a sufficient quantity of conveyed fluid for lubricating the bearing 26 over a longer period. The disc-shaped element 32 is fastened to the ring 16 by means of a screw 40. The recirculation of the conveyed fluid out of the coupling chamber 20 into the impeller chamber 14 therefore takes place via a radial bearing gap 52 in the bearing 26. The radial bearing gap 52 is arranged between the bearing elements of the impeller-side radial bearing 26b of the bearing 26, which ensures lubrication between the bearing elements even when the pump is in dry-run condition. The radial bearing gap 52 restricts the recirculation of the conveyed fluid out of the coupling chamber 20 into the impeller chamber 14. As can be seen, the impeller-side radial bearing 26b of the bearing 26 does not comprise a lubrication groove, in order to restrict the recirculation of the conveyed fluid. In the coupling-side radial bearing 26a of the bearing 26, a lubrication groove 54 can be discerned which ensures sufficient flushing between the bearing elements. The impeller 24 comprises a hollow-cylindrical portion 42 which extends in the axial direction of the pump shaft 22 and adjoins the disc-shaped element 32.

(4) The leaking of conveyed fluid out of the bearing 26 into the impeller chamber 14 is limited by the gap between the disc-shaped element 32 and the portion 42. A restriction element 34 which is arranged between the impeller chamber 14 and the opening 36 of the duct 28 is provided. The restriction element 34 prevents any accumulation of particles in the coupling chamber in the event of the flow of fluid being laden with solids. The restriction element 34 restricts the throughflow of the conveyed fluid through the duct 28. The restriction element 34 is formed on the disc-shaped element 32 and covers the duct opening 36. The restriction element 34, according to the invention, rests against the duct opening 36 such that the conveyed fluid can flow into the region between the restriction element 34 and duct opening 36. To this end, the restriction element 34 comprises on its outer circumference a chamfer 38 which is arranged on the side of the element 32 remote from the impeller 24. A gap 48 through which conveyed fluid can flow into the duct 28 is produced between the restriction element 34 and ring 16. The restriction element 34 in this manner effects that particles to have to move radially inwards into the duct 28 against the centrifugal force, in order to enter the coupling chamber 20. The partial flow of the conveyed fluid which arrives in the coupling chamber out of the impeller chamber 14 to the bearing 26 for the purpose of lubricating the bearing 26 is considerably reduced by the restriction element 34, as a result of which the introduction of particles into the can 18 in the event of the flow of fluid being laden with solids is reduced. The restriction element 34 in this manner restricts the flow of conveyed fluid through the duct 28. The pump shaft 22 of the magnetic drive pump 10 is formed such that it does not produce a fluidic connection between the coupling chamber 20 and the impeller chamber 14. To this end, the pump shaft 22 is formed as a solid body.

LIST OF REFERENCE CHARACTERS

(5) 10 magnetic drive pump 12 housing 14 impeller chamber 16 ring 18 can 20 coupling chamber 22 pump shaft 24 impeller 26 bearing 26a coupling-side radial bearing 26b impeller-side radial bearing 28 duct 30 drainage bore 32 disc-shaped element 34 restriction element 36 duct opening 38 chamfer 40 screw 42 impeller end region running in the longitudinal direction 44 inlet 46 outlet 48 gap 50 rotor 52 radial bearing gap 54 lubrication groove