CENTRIFUGAL PUMP DEVICE

Abstract

A centrifugal pump device has at least one impeller (16), a circulation connection between a delivery side (22) of the at least one impeller (16) and a suction side (20) of the at least one impeller (16), and a valve arrangement (30, 46) in said circulation connection (44, 54). The valve arrangement (30, 46) has a first valve mode providing a pressure dependent shut-off valve (46) in the circulation connection. The valve arrangement (30, 46) allows a change between the first valve mode and at least one further valve mode. The at least one further valve mode provides at least one fixed closing degree of the circulation connection (44, 54).

Claims

1. A centrifugal pump device comprising: at least one impeller; a circulation connection between a delivery side of the at least one impeller and a suction side of the at least one impeller; and a valve arrangement in said circulation connection, the valve arrangement having a first valve mode providing a pressure dependent shut-off valve in said circulation connection, and at least one further valve mode providing at least one fixed closing degree of the circulation connection, wherein said valve arrangement allows a change between the first valve mode and the at least one further valve mode.

2. The centrifugal pump device according to claim 1, wherein in the at least one further valve mode the circulation connection is closed.

3. The centrifugal pump device according to claim 1, wherein in the at least one further valve mode the circulation connection has a fixed open cross section or a fixed minimum open cross section.

4. The centrifugal pump device according to claim 1, wherein the further valve mode comprises a second valve mode in which the circulation connection is closed and a third valve mode in which the circulation connection has a fixed open cross section or a fixed minimum open cross section.

5. The centrifugal pump device according to claim 1, wherein the valve arrangement comprises a selector for changing the valve mode.

6. The centrifugal pump device according to claim 1, wherein said valve arrangement comprises a single valve device providing the different valve modes and forming the shut-off valve in the first valve mode.

7. The centrifugal pump device according to claim 1, wherein: said valve arrangement comprises a selector valve arranged in said circulation connection; the selector valve comprises a first port connected to a circulation channel comprising the shut-off valve and a movable valve element which in the first valve mode opens the first port and in the second valve mode closes the first port.

8. The centrifugal pump device according to claim 7, wherein: the selector valve comprises a second port connected to a bypass circulation channel bypassing the shut-off valve and providing a circulation connection having a fixed open cross section; and in one of the first valve mode and the at least one further valve mode the movable valve element of the selector valve opens the second port.

9. The centrifugal pump device according to claim 7, wherein: the further valve mode comprises a second valve mode in which the circulation connection is closed and a third valve mode; the movable valve element in the first valve mode opens the first port and closes the second port; the movable valve element in the second valve mode closes the first and the second port; and the movable valve element in the third valve mode opens the first and the second port.

10. The centrifugal pump device according to claim 7, wherein the selector valve comprises an outlet port connected to the suction side of the at least one impeller and wherein the valve element in the first valve mode provides a fluid connection between the first port and the outlet port, and in the further valve mode provides a fluid connection between the first and the second port and the outlet port.

11. The centrifugal pump device according to claim 9, wherein said movable valve element of the selector valve has at least three selectable valve positions defining three different valve modes.

12. The centrifugal pump device according to claim 7, wherein the selector valve comprises an actuating element configured to switch the valve element between the different valve positions defining the valve modes.

13. The centrifugal pump device according to claim 12, wherein the actuating element is configured to manually change the valve position, wherein the actuating element and comprises a grip portion or a tool engagement portion or both a grip portion and a tool engagement portion.

14. The centrifugal pump device according to claim 12, further comprising removable cover element, wherein the actuating element is covered by the removable cover element.

15. The centrifugal pump device according to claim 7, wherein: the selector valve comprises a rotatable valve element, which is rotatable between different valve positions corresponding to the first valve mode and at least one further valve mode; the movable valve element comprises a valve wall extending concentrically about a rotational axis of the moveable valve element and interacting with at least one opposing valve opening, and the valve wall encircles a free space in fluid connection with the suction side of the impeller.

16. The centrifugal pump device according to claim 1, further comprising at least another impeller to provide two or more impellers, wherein the pump device is a multistage pump having the two or more impellers arranged in series; said circulation connection connects the delivery side of one impeller or a group of impellers with the suction side of the first impeller with respect to a flow direction through the centrifugal pump device.

17. The centrifugal pump device according to claim 1, wherein the centrifugal pump device is configured for use as booster pump for domestic water supply.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In the drawings:

[0030] FIG. 1 is a perspective view showing a centrifugal pump device according to the invention;

[0031] FIG. 2 is a cross sectional view of the centrifugal pump device according to FIG. 1;

[0032] FIG. 3 is an enlarged cross sectional view of the valve arrangement of a circulation connection;

[0033] FIG. 4 is a detail view of a selector valve in a first valve mode;

[0034] FIG. 5 is a detail view of the selector valve according to FIG. 4 in a second valve mode;

[0035] FIG. 6 is a detail view of the selector valve according to FIGS. 4 and 5 in a third valve mode; and

[0036] FIG. 7 is a front view of the centrifugal pump device with removed cover element.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0037] Referring to the drawings, a centrifugal pump device as shown is a booster pump for domestic water supply and is built as an integrated unit integrating a pump and an electric drive motor in a surrounding housing 2. On the housing 2 there is arranged an inlet connection 4 and an outlet connection 6 for connection with a piping inside a building. Near the bottom there is provided a drain screw 8 which can be opened for draining the interior of the pump. On top of the housing 10 there is arranged a control panel 10.

[0038] Inside the housing 2 there is arranged an electric drive motor 12 connected to a drive shaft 14 which is connected to three impellers 16 arranged in series. Thus, in this example the centrifugal pump is a multistage pump having three stages. Between the impellers there are arranged diffusers 17 as usual for those multistage pumps. The inlet 18 of the first impeller is open towards a suction space 20 which is connected with the inlet connection 4. The outlet of the third impeller is open towards an outlet channel 22 surrounding the diffuser arrangement. The outlet channel 22 is connected to the outlet connection 6 via the opening 23.

[0039] The shown centrifugal pump comprises a self-priming means 24 shown in more detail in FIGS. 3 to 7.

[0040] The self-priming means 24 comprises a circulation connection having an outlet port 26 which is open towards a suction space 20 via the entrance opening 28 of the suction space 20. The outlet port 26 is the outlet port of a selector valve 30 of a valve arrangement in said self-priming means 24. The selector valve 30 comprises a rotatable valve element 32. The valve element 32 has tool engagement portion 34 into which a tool for rotating the valve element can be inserted. The tool engagement portion 34 is covered by a housing portion 36 forming a part of the housing 2. Therefore, before setting the selector valve by moving the rotatable valve element 32 the housing portion 36 has to be removed. After setting the selector valve the housing portion 36 can be attached and the tool engagement portion 24 cannot be seen or engaged from the outside anymore. Thus, in this embodiment the housing portion 36 forms a cover element covering the selector valve. By this a change of the valve position during operation can be prevented.

[0041] The valve element 32 is arranged in a circular receiving space 38 having a circumferential wall with a first opening or port 40 and a second opening or port 42. The first port 40 is open towards a circulation channel 44 connected to the outlet channel 22 via passage 45. In the circulation channel 44 there is arranged a shut-off valve 46. The shut-off valve 46 comprises a movable valve element 48 biased by a spring 50. With increasing pressure in the circulation channel the valve element 48 is moved against the biasing force of the spring 50 until the valve element 58 abuts against the valve seat 52 and closes the circulation channel 42.

[0042] The second port 42 is open towards a bypass channel 54. On the opposite side the bypass channel 54 is also open towards the outlet channel 22 via passage 45. Thus, the bypass channel 54 forms a circulation connection in parallel to the circulation channel 44. The bypass channel 54 does not comprise a valve assembly and provides a fixed cross section.

[0043] The valve element 32 of the selector valve 30 has two openings 56 inside the cylindrical valve wall. The valve wall with the two openings 56 encircles a free space 58 inside the valve element 32, which free space 58 is connected to the outlet port 26. The openings 56 are arranged such that by rotating the valve element 32 they can be brought into a position aligned with the ports 40 and 42. The selector valve has three possible valve positions or valve modes which may be defined for example by detents engaging the valve element 32. The three different valve modes are defined by three different valve position I, II and III in different angular positions about the rotational axis of the valve element 32 as best shown in FIG. 7. The first valve position I corresponds to a valve mode providing self-priming of the pump. The second valve position II offers a second valve mode not offering any self-priming. The third valve position III in an angular position between the first and second valve position corresponds to a third valve mode offering improved air handling as described in more detail below.

[0044] FIG. 4 shows the first valve mode or valve position in which one of the openings 56 is aligned with the first port 40, whereas the valve wall 60 closes the second port 42. In this valve position the free space 58 is connected to the circulation channel 44 via one opening 56 and the first port 40. In this valve position the pump offers a self-priming functionality. The spring 50 keeps the shut-off valve open until a predefined outlet pressure on the delivery side, i.e. inside the outlet channel 22 is achieved. Then, by this pressure the valve element 48 is forced against the valve seat 54 and the circulation channel 44 is closed for the following further operation of the pump.

[0045] FIG. 5 shows the second valve mode of the valve arrangement consisting of the selector valve 30 and the shut-off valve 46. In this second valve mode the valve element 32 is rotated such that both the first port 40 and the second port 42 are covered by the valve wall 60 and, thus, the circulation channel 44 and the bypass channel 54 are closed. In this second valve mode the self-priming functionality is switched-off, i.e. the circulation connection is completely closed. This mode may be used in applications where no self-priming functionality is necessary, since for example a dry running of the pump is not expected.

[0046] FIG. 6 shows the third valve mode providing an improved air handling. In this valve mode the valve element 32 is in its third valve position in which the two openings 56 are aligned with the first port 40 and the second port 42 so that the first and the second ports are opened towards the free space 58 and further to the inlet side of the first impeller. Thus, both the circulation channel 44 and the bypass channel 54 together form a circulation connection between the delivery side, i.e. the outlet channel 22 and the suction space 20. In this configuration the circulation channel 44 is open as long as a predefined pressure in the outlet channel 22 is not reached. If the pressure defined by the load of the spring 50 is reached the biasing force of the spring 50 is overcome and the valve element 48 is pressed against the valve seat 52. Thus, the circulation channel 44 is closed. The bypass channel 54, however, which does not comprise any valve element is kept open and ensures a continued minimal self-priming during the further operation of the pump. This third valve mode is suitable in applications having a greater amount of air or gas in the water to be pumped. The continued minimal self-priming avoids an alternating opening and closing of the valve element 48. This can reduce the noise occurring from opening and closing the shut-off valve 46 and can improve the operation of the pump.

[0047] 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.

REFERENCES

[0048] 2 housing [0049] 4 inlet connection [0050] 6 outlet connection [0051] 8 drain screw [0052] 10 control panel [0053] 12 electric drive motor [0054] 14 drive shaft [0055] 16 impeller [0056] 17 diffusers [0057] 18 inlet [0058] 20 suction space [0059] 22 outlet/delivery channel [0060] 23 opening [0061] 24 self-priming means [0062] 26 outlet port [0063] 28 entrance opening [0064] 30 selector valve [0065] 32 valve element [0066] 34 tool engagement portion [0067] 36 housing portion, cover element [0068] 38 receiving space [0069] 40 first port [0070] 42 second port [0071] 44 circulation channel [0072] 45 passage [0073] 46 shut-off valve [0074] 48 valve element [0075] 50 spring [0076] 52 valve seat [0077] 54 bypass channel [0078] 56 openings [0079] 58 free space [0080] 60 valve wall [0081] I, II, III valve positions