WASTE WATER PUMP

Abstract

A waste water pump includes an impeller (12) and a surrounding pump housing (4), wherein an impeller side chamber (20) is formed between the impeller (12) and the pump housing (4). The impeller side chamber (20) has a first seal (16) between the impeller (12) and the pump housing (4), towards the intake side (32) of the impeller (12), and a second seal (18) between the impeller (12) and the pump housing (4), towards the pressure side (14) of the impeller (12). The first seal (16) is provided with a conveying device (28, 30) configured to convey debris from the impeller side chamber (20) to the intake side (32) of the impeller (12). The second seal (18) is provided with conveying device (38, 40) configured to convey debris from the side chamber (20) to the pressure side (14) of the impeller (12).

Claims

1. A waste water pump comprising: an impeller; a pump housing surrounding the impeller, wherein an impeller side chamber is formed between the impeller and the pump housing; a first seal, said impeller side chamber having the first seal between the impeller and the pump housing towards an intake side of the impeller; and a second seal, said impeller side chamber having the second seal between the impeller and the pump housing towards a pressure side of the impeller, wherein the first seal is provided with a first seal conveying means configured to convey debris from the impeller side chamber to the intake side of the impeller and the second seal is provided with a second seal conveying means configured to convey debris from the side chamber to the pressure side of the impeller.

2. A waste water pump according to claim 1, wherein the second seal comprises a first annular sealing surface and a facing second annular sealing surface, said first sealing surface having a helical groove as the conveying means.

3. A waste water pump according to claim 2, wherein said second annular sealing surface has at least one cut out at one circumferential position and/or at least one helical groove.

4. A waste water pump according to claim 2, wherein: the first annular sealing surface is disposed on the pump housing; and the facing second annular sealing surface is disposed on the impeller.

5. A waste water pump according to claim 3, wherein the at least one cut out extends across the second annular sealing surface transverse to a circumferential direction.

6. A waste water pump according to claim 3, wherein the at least one cut out extends across the second annular sealing surface parallel and/or radial to a rotational axis of the impeller.

7. A waste water pump according to claim 3, wherein the second sealing surface is a smooth surface except the at least one cut out.

8. A waste water pump according to claim 3, wherein: the impeller has at least one radial protrusion between the first and the second seal; and said at least one cut out is disposed on the impeller at a position in front of said protrusion in a rotational direction of the impeller.

9. A waste water pump according to claim 8, wherein said protrusion is a counterweight for balancing the impeller.

10. A waste water pump according to claim 2, wherein the helical groove in the first annular sealing surface of the second seal twists in a rotational direction of the impeller such that the groove ascends toward the pressure side of the impeller.

11. A waste water pump according to claim 1, wherein the first seal comprises a first annular sealing surface on the impeller and a facing second annular sealing surface on the pump housing.

12. A waste water pump according to claim 11, wherein the first annular sealing surface and the second annular sealing surface of the first seal each have a helical groove.

13. A waste water pump according to claim 12, wherein the helical grooves of the first sealing surface and the second sealing surface twist in opposite directions.

14. A waste water pump according to claim 12, wherein the helical groove on the second annular sealing surface twists in a rotational direction of the impeller such that the helical groove on the second annular sealing surface ascends toward the suction side of the impeller.

15. A waste water pump according to claim 1, wherein: the first seal comprises a first annular sealing surface on the impeller and extending in a direction parallel to or inclined to a rotational axis of the impeller and a facing second annular sealing surface on the pump housing and extending in a direction parallel to or inclined to a rotational axis of the impeller; and the second seal comprises a first annular sealing surface extending in a direction parallel to or inclined to a rotational axis of the impeller and a facing second annular sealing surface extending in a direction parallel to or inclined to a rotational axis of the impeller.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In the drawings:

[0025] FIG. 1 is a partly sectioned entire view of a waste water pump according to the invention, in the form of a submersible pump assembly;

[0026] FIG. 2 is a detailed view of the impeller and a sealing ring of a first sealing of the pump according to FIG. 1; and

[0027] FIG. 3 is a cross section of the pump housing of the pump according to FIG. 1 with the impeller removed from the pump housing.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] Referring to the drawings, the shown waste water pump is configured as a submersible pump assembly with an electric drive motor 2 and with a pump housing 4 connected to the electric drive motor. In this example the pump housing 4 is arranged on the lower end of the drive motor 2 and connected to the electric drive motor 2 by a clamping ring 6. The pump housing 4 on its lower side is provided with a central opening 8 which forms the intake opening or the suction port of the pump assembly. A pressure connection 10 on which an outlet conduit may be connected extends in the lateral direction, radially to the rotational axis X. An impeller 12 is arranged in the inside of the pump housing 4 which is configured as a spiral housing surrounding the impeller. In this case the impeller 12 is configured as a single-channel impeller. However, a different design of the impeller may be possible. Inside the pump housing 4 there is a spiral chamber 14 surrounding the pressure side of the impeller 12 and connected to the pressure connection 10. The spiral chamber 14 forms a pressure channel or pressure space inside the pump housing 4.

[0029] Between the central opening 8 forming the intake port or intake side of the pump assembly and the spiral chamber 14 there is arranged a sealing assembly between the pump housing 4 and the impeller 12. This sealing assembly consists of two sealings spaced from one another. A first sealing 16 is arranged close to the intake side of the impeller, i.e. the central opening 8 of the pump housing 4. The second sealing 18 is arranged adjacent to the spiral chamber 14. Between the first sealing 16 and the second sealing 18 there is provided an impeller side chamber 20 or intermediate chamber, respectively. The impeller side chamber 20 is a free space between the outer circumference of the impeller 12 and the surrounding wall of the pump housing 4.

[0030] In this example the first sealing 16 is a lower sealing. This sealing is formed by a sealing ring 22 fixed inside the pump housing 4 surrounding the central opening 8. The first sealing 16 is formed by a first annular sealing surface 24 formed on the outer circumference of the impeller 12 concentric to the rotational axis X and a second annular sealing surface 26 provided on the inner circumference of the sealing ring 22. When the impeller 12 is inserted into the pump housing 4 as shown in FIG. 1 the first annular sealing surface 24 on the impeller 12 is facing the second annular sealing surface 26 inside the sealing ring 22. The first annular sealing surface 24 is provided with a first helical groove 28 winding or twisting around the rotational axis X. The second annular sealing surface 26 is provided with a second helical groove 30 also winding or twisting around the rotational axis X. The helical grooves 28 and 30 are arranged such that they do not engage with one another but that the outer circumference of the first annular sealing surface is in contact with the inner circumferential surface of the second annular sealing surface 26 or distanced by a sealing gap. This means, preferably the crests of the two facing threads formed by the first helical groove 28 and the second helical groove 30 are in contact with one another or spaced by the sealing gap. The first helical groove 28 and the second helical groove 30 in this example have the same pitch, but are inclined in opposite directions. This means the first helical groove and the second helical groove are wound or twisted in opposite directions around the rotational axis X. The second helical groove 30 forming the outer helical groove twists in the rotational direction R of the impeller such that the grooves extend ascends toward the suction side of the impeller, i.e. the central opening 8. Accordingly, the first helical groove 28 on the first annular sealing surface 24 is wound such that the groove ascends away from the suction side 32 of the impeller.

[0031] The design of the first sealing 26 as described forgoing may also be used as a single sealing independent from a second sealing 18 as described in the following.

[0032] The second sealing 18 consists of a first annular sealing surface 34 formed in an opening of the pump housing 4 surrounding the impeller 12 and a facing second annular sealing surface 36 provided on the outer circumference of the impeller 12. The first annular sealing surface 34 is provided with a helical groove 38 similar to the helical groove 30 provided in the sealing ring 22. However, the helical groove 38 is wound in opposite direction such that it in the rotational direction R of the impeller 12 ascends toward the pressure side, i.e. the spiral chamber 14. When the impeller 12 is inserted into the pump housing 4 as shown in FIG. 1 the second annular sealing surface 36 is facing the first annular sealing surface 34. Thereby, the crests of the thread formed by the helical groove 38 preferably are in contact with the second annular sealing surface 36. The second annular sealing surface 36 in this embodiment is formed as a smooth surface with one cut out 40. The cut out 40 traverses the sealing surface 36 normal to the circumferential direction, i.e. parallel to the rotational axis X. Thereby, the cut out 40 connects the impeller side chamber 20 with the spiral chamber 14.

[0033] In the region of the impeller 12 forming the inner wall of the impeller side chamber 20 there is provided a protrusion 42 acting as a counterweight for balancing the impeller. When the impeller 12 is rotating inside the pump housing 4 this protrusion 42 produces a pressure wave inside the impeller side chamber 20. Since the cut out 40 is arranged in front of the protrusion 42 (seen in the rotational direction R) the pressure wave causes a fluid flow through the cut out from the impeller side chamber 20 towards the spiral chamber 14.

[0034] When the impeller 12 is rotating inside the pump housing the described helical grooves act as conveying means conveying debris like particles or fibers out of the impeller side chamber. Because of the opposite twisting of the two helical grooves 30 and 38 in the first sealing 16 and the second sealing 18 debris is conveyed through the first sealing 16 toward the suction side, i.e. towards the central opening 8 and the suction side 32 of the impeller 12. In the second sealing 18 debris is conveyed in the opposite direction towards the spiral chamber 14. The conveying of fibers or debris in a direction transverse to the rotational direction R is caused by the first helical groove 28 on the first sealing surface 24 of the first sealing 16 and the cut out 40 in the second annular sealing surface 36 of the second sealing 18. These elements act as drivers or driving means moving particles or fibers entering the respective sealing in rotational direction. When those fibers or particles come into contact with the outer helical grooves 30 and 38 inside the outer sealing surfaces they are moved along the helical grooves 30 and 38 through the respective sealing 16, 18 out of the impeller side chamber 20. At the same time in particular the cut out 40 may act as means for fragmenting those solid matters to be conveyed through the sealing.

[0035] While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.