PUMP WITH A LIFTING DEVICE

Abstract

A pump includes a lifting device, a housing in which a shaft is arranged, a relief element connected to the shaft, and a contact element. The lifting device includes a spring and a thrust element. In a start-up or shut-down state, a spring force is transmitted to the shaft via the thrust element by the spring, separating the relief element and the counter element. The contact element is between the spring and the thrust element and a side of the thrust element facing the spring is flow-connected to a high-pressure side, and a side of the contact element facing the spring is flow-connected to a low-pressure side such that the thrust element and the contact element are spaced apart by a pressure difference generated between the side of the contact element facing the spring and the side of the contact element facing the thrust element.

Claims

1. A pump comprising: a lifting device configured to compensate for axial thrust of a shaft of the pump; a housing having an inlet for a fluid on a low-pressure side and an outlet for the fluid on a high-pressure side of the pump, and in which the shaft is arranged; a relief element connected to the shaft in a torque-proof manner and a counter element connected to the housing; the lifting device comprising a spring and a thrust element connected to the shaft in a torque-proof manner, and in a start-up state or shut-down state of the pump, a spring force directed in an opposite direction to the axial thrust is capable of being transmitted to the shaft via the thrust element by the spring, so that the relief element and the counter element are separated from each other; and a contact element arranged between the spring and the thrust element and a side of the thrust element facing the spring is flow-connected to the high-pressure side in such a way, and a side of the contact element facing the spring is flow-connected to the low-pressure side in such a way that the thrust element and the contact element are capable of being be spaced apart by a pressure difference which is configured to be generated between the side of the contact element facing the spring and the side of the contact element facing the thrust element.

2. The pump according to claim 1, further comprising a relief chamber arranged in the housing, the side of the contact element facing the spring being flow-connected to the low-pressure side via the relief chamber.

3. The pump according to claim 1, wherein the side of the contact element facing the spring is flow-connected to the inlet of the pump and the side of the thrust element facing the spring is flow-connected to a pumping stage of the pump so that the pressure difference which is configured to be generated corresponds to a pressure difference between a suction pressure and a pumping pressure of the pump.

4. The pump according to claim 1, wherein the contact element and the spring are arranged stationary on the housing.

5. The pump according to claim 1, wherein a seal is arranged between the contact element and the housing in such a way that the side of the contact element facing the spring and the side of the thrust element facing the spring are sealed against each other.

6. The pump according to claim 1, wherein the lifting device is arranged on one end of the shaft.

7. The pump according to claim 1, wherein the lifting device is arranged on a non-drive side of the pump.

8. The pump according to claim 1, wherein the pump is a multistage pump with at least a first pump stage and a second pump stage, and the side of the thrust element is included in one of the first or the second pump stage.

9. The pump according to claim 1, wherein the shaft is rotatably supported in a shaft bearing.

10. The pump according to claim 9, wherein the shaft bearing is a radial bearing.

11. The pump according to claim 9, wherein the shaft bearing is a plain bearing.

12. The pump according to claim 1, wherein the spring is a spiral spring or a disk spring.

13. The pump according to claim 1, wherein the pump is a product-lubricated pump.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The invention will be explained in more detail hereinafter with reference to the drawings.

[0028] FIG. 1 is a schematic representation of a pump according to an embodiment of the invention; and

[0029] FIG. 2 is a further schematic representation of a pump according to an embodiment of the invention.

DETAILED DESCRIPTION

[0030] FIG. 1 shows a schematic representation of a pump 1 according to an embodiment of the invention.

[0031] The pump 1 according to an embodiment of the invention is designed as a product-lubricated multistage pump 1 and comprises a lifting device 10 for compensating an axial thrust A of a shaft 2 of the pump 1 in a predeterminable operating state, especially during a start-up state and/or shut-down state of the pump 1. Due to the fact that the pump 1 is product-lubricated, a very compact design is possible, because most parts are in direct contact with a fluid. As a consequence, no additional oil-lubricated bearings are required and therefore no mechanical seal is needed to separate the bearings from the fluid. Due to this fact, the lifting device 10 is designed in such a way that it can work with contact to the fluid.

[0032] Here, the pump 1 further comprises a housing 3 in which the shaft 2 is arranged, and which housing 3 comprises an inlet for a fluid on a low-pressure side and an outlet for the fluid on a high-pressure side of the pump, wherein the pump further comprises a relief element 5 connected to the shaft 2 in a torque-proof manner and a counter element 6 connected to the housing 3.

[0033] The lifting device 10 comprises a spring 11 and a thrust element 12 connected to the shaft 2 in a torque-proof manner. A contact element 13 is arranged between the spring 11 and the thrust element 12 which, like the spring 11, is arranged on the housing 3. In this embodiment, the housing 3 can be designed in several parts and comprise a pump housing and a housing part for the lifting device 10. The housing part for the lifting device 10 is arranged on the pump housing, in particular screwed on it.

[0034] In a start-up state and/or a shut-down state of the pump 1, a spring force F directed in the opposite direction to the axial thrust A is transmitted to the shaft 2 via the thrust element 12 by the spring 11, so that the relief element 5 and the corresponding counter element 6 are separated from each other. For this purpose, the spring 11 is designed as a pressure spring.

[0035] In an operating state of the pump 1, the feed pressure is generated by the rotation of the shaft 2 with the pump impellers (not shown here), so that the fluid is conveyed from the inlet on the low-pressure side to the outlet on the high-pressure side of the pump 1. This feed pressure is used in the pump 1 to space apart the contact element 13 and the thrust element 12 in a normal operating state, so that wear after the start-up state and/or before the shut-down state (i.e. in “normal” operating state) is avoided.

[0036] The lifting device 10 according to the invention can prevent wear during the normal operating state, since the side of the contact element 13 facing the thrust element 12 is flow-connected to the high-pressure side in such a way and the side of the contact element 13 facing the spring 11 is flow-connected to the low-pressure side in such a way that the thrust element 12 and the contact element 13 can be spaced apart by a pressure difference which can be generated between the side of the contact element 13 facing the spring 11 and the side of the contact element 13 facing the thrust element 12.

[0037] The fact that the thrust element 12 and the contact element 13 are spaced apart means that a distance between the spring 11 and the thrust element 12 is increased and a distance between the contact element 13 and the thrust element 12 is increased, whereby the spring 11 is compressed. As a consequence, the spring force F is not transmitted to the thrust element 12 in the normal operating state and there is no contact between thrust element 12 and contact element 13.

[0038] The pressure difference that can be generated corresponds to a pressure difference between a suction pressure and a pumping pressure of the pump 1. The suction pressure is a pressure at the inlet of the pump 1 and the pumping pressure is a pressure at a pump stage of the pump 1.

[0039] During the start-up state and/or shut-down state, the pressure difference between the pumping pressure and suction pressure corresponds to a value in such a way that the contact element 13 is moved in the direction of the thrust element 12, (opposite direction to the axial thrust A) i.e. is moved in the direction of the spring force F (to the left looking at FIG. 1) and is thus in contact with the thrust element 12 in order to separate the relief element 5 and the corresponding counter element 6 from each other. The spring force F thus overcomes the pressure difference between pumping pressure and suction pressure.

[0040] However, in the normal operating state, the suction pressure is so much lower than the pumping pressure (the spring force F is not great enough to overcome the pressure difference between pumping pressure and suction pressure) that the contact element 13 is moved away from the thrust element 12 (in the direction of the axial thrust A, to the right looking in FIG. 1), i.e. moved in the opposite direction to the spring force F, in order to avoid in this way the contact with the thrust element 12 rotating with shaft 2. A high-pressure chamber 120 is arranged between the contact element 13 and the thrust element 12. In the operating state, the high-pressure chamber 120 is filled with the fluid and is under the pumping pressure because it is flow-connected to the pump stage via the pipes/boreholes 121. A low-pressure chamber 130 on the side of the contact element 13 facing the spring 11, in which the spring 11 is arranged, is also filled with the fluid and is under the suction pressure, because it is flow-connected to the inlet of the pump 1 via the borehole/pipe, in particular flow-connected to the inlet of the pump 1 via the relief chamber 4. The contact element 13 and the spring 11 are arranged on the housing 3 of the pump 1.

[0041] A seal is arranged between the contact element 13 and the housing 3 to seal the high-pressure chamber 120 and the low-pressure chamber 130 against each other.

[0042] The shaft 2 of the pump 1 is rotatably supported in a shaft bearing 20. Here, the shaft bearing 20 is a pure radial bearing 20. The radial bearing 20 is product-lubricated and can comprise silicon carbide. An axial bearing of the pump 1 is achieved by the relief element 5 and the counter element 6.

[0043] The lifting device 10 is arranged on the non-drive side of the pump 1 and the thrust element 12 is preferably screwed onto a stub of the shaft 2 by a screw 32.

[0044] FIG. 2 shows a further schematic representation of a pump 1 according to the invention, which has an analogous structure to the pump according to FIG. 1.

[0045] In the operating state of the pump 1, the feed pressure is generated by the rotation of the shaft 2 with the pump impellers 21, so that the fluid is conveyed from the inlet on the low-pressure side to the outlet 100 on the high-pressure side of the pump 1. Due to the feed pressure, the contact element 13 and the thrust element 12 are spaced from each other in the normal operating state, so that wear of the spring 11/the contact element 13 and the thrust element 12 after the start-up state and/or before the shut-down state (i.e. in the “normal” operating state) is avoided.

[0046] The pressure difference that can be generated corresponds to the pressure difference between the suction pressure and the pumping pressure of the pump 1. The suction pressure is the pressure at the inlet of the pump 1 and the pumping pressure is the pressure at the pumping stage 101 of the pump 1.

[0047] During the start-up state and/or shut-down state, the pressure difference between the pumping pressure and suction pressure corresponds to a value in such a way that the contact element 13 is moved in the direction of the thrust element 12, (opposite direction to the axial thrust A), i.e. is moved in the direction of the spring force F (to the left looking at FIG. 2) and is thus in contact with the thrust element 12 in order to separate the relief element 5 and the corresponding counter element 6 from each other. This means that the spring force F overcomes the pressure difference between pumping pressure and suction pressure.

[0048] In the normal operating state, however, the suction pressure is so lower than the pumping pressure (the spring force F is not great enough to overcome the pressure difference between pumping pressure and suction pressure) that the contact element 13 is moved away from the thrust element 12 (in the direction of the axial thrust A, to the right looking at FIG. 2), i.e. is moved in the opposite direction to the spring force F, in order to avoid the contact with the thrust element 12 rotating with the shaft 2. The high-pressure chamber 120 is arranged between the contact element 13 and the thrust element 12. In the operating state, the high-pressure chamber 120 is filled with the fluid and is under the pumping pressure, because it is flow-connected to the pump stage 101 via the pipes/boreholes 121.

[0049] The low-pressure chamber 130 on the side of the contact element 13 facing the spring 11, in which the spring 11 is arranged, is also filled with the fluid and is under the suction pressure, because it is flow-connected to the inlet of the pump 1 via the borehole/pipe 131 and via the relief chamber 4 (since the relief chamber is flow-connected to the suction pipe of the pump).