GB2444576A

GB2444576A - Pump assembly

Info

Publication number: GB2444576A
Application number: GB0713206A
Authority: GB
Inventors: John Toseland
Original assignee: SPP Pumps Ltd
Current assignee: SPP Pumps Ltd
Priority date: 2006-12-04
Filing date: 2007-07-06
Publication date: 2008-06-11
Anticipated expiration: 2027-07-06
Also published as: GB2444576B; GB0624235D0; GB0713206D0

Abstract

The present invention relates to a system and a bearing arrangement for said system. Particularly, but not exclusively, the invention relates to a vertical turbine water pump system and a bearing arrangement therefore. A system 1 is provided which comprises a compact bearing arrangement 2, a housing 3, and a rotating shaft 4, supported by the bearing arrangement 2 and having a spacer coupling 6, removable to provide a discontinuity in the rotating shaft 4. The bearing arrangement 2 is removably mounted to a mounting element 8 of the housing 3 on the side of the mounting element 8 adjacent the spacer coupling 6. The arrangement allows access to the components of the system for servicing and maintenance. Also disclosed is a bearing arrangement that includes a self regulating lubricating system that has a working lubricant reservoir (16, fig 3) and a return lubricant reservoir (18, fig 3), and also a system that includes a beating arrangement that is mounted in a housing in such a way that airflow cools the bearing.

Description

1 2444576 PUMP ASSEMBLY.

The invention relates to pumps and further relates to a bearing arrangement for a pump, particularly, but not exclusively, to a bearing arrangement for a vertical turbine water pump.

Environmental considerations have led to increased interest in the operating efficiency of products. End users are also beginning to realise the cost benefits of choosing the most efficient products. Over the lifetime of, for example, a large water pump, these cost benefits could be considerable. As energy prices continue to rise, the importance of efficiency to end users is likely to increase still further.

Along with energy costs, a large proportion of the running costs of a water pump, or indeed any other large piece of equipment, is associated with maintenance. As well as the cost of maintenance work itself, there are costs relating to down time' when the equipment is out of service and awaiting repair.

Accordingly, it is an object of the present invention to provide an improved bearing arrangement, having increased efficiency and life span, while also allowing simplified removal and service.

Vertical turbine water pumps are generally designed with a large drive motor positioned in a headpiece at the top of a housing. A rotating shaft runs from the motor down through a bearing arrangement seated on a shaft, and through a mechanical seal to an impeller or similar means to pump the water up from below ground. Because of this arrangement it was often necessary to remove the motor from the top of the housing to gain access to any of the other parts for servicing. The removal of the motor requires dismantling of the headpiece, and the use of heavy lifting equipment. It is, therefore, a costly and time-consuming process.

it is known to incorporate a spacer coupling into the shaft between the bearing arrangement and the mechanical seal to allow a worn seal to be removed and serviced or replaced without removing the motor. An opening is provided in the side of the housing providing access to the spacer coupling and allowing removal and replacement of the seal as required. This greatly simplifies servicing and maintenance of the seal component, and has been an extremely popular addition to this type of pump.

However, servicing of the bearing arrangement is still only possible after removal of the drive motor from the headpiece of the pump. This is because the size of the bearing arrangement and the way in which it is seated make any other access impossible.

According to a first aspect of the present invention there is provided a system comprising a compact bearing arrangement, a housing, and a rotating shaft, supported by the bearing arrangement and having a spacer coupling, removable to provide a discontinuity in the rotating shaft, wherein the bearing arrangement is removably mounted to a mounting element of the housing on the side of the mounting element adjacent the spacer coupling.

The smaller size of the new bearing arrangement, made possible by design improvement and the elimination of cooling jackets, together with its mounting means and the spacer coupling, greatly simplify removal of the bearing arrangement from the system. Minimal dismantling of the system is required leading to fast and simpler servicing.

Further features of the invention are provided as recited in any of claims 2 to 6.

For simplicity of mounting of the bearing arrangement, the mounting element is preferably a flange. An aperture is preferably provided in the housing, in the region of the spacer coupling, to facilitate removal of the spacer coupling and other components from the system.

In the case where the rotating shaft is oriented vertically, the bearing arrangement is preferably mounted to the bottom of a flange above the spacer coupling. This allows the bearing arrangement to be lowered out of the system once the spacer coupling has been removed.

It is particularly advantageous if the system allows removal of the bearing arrangement and of another component, for example a seal, by a common process. This is achievable if the seal element is positioned on the opposite side of the spacer coupling from the bearing arrangement.

Spherical roller thrust bearings are known to produce a pumping action that may be employed to pump oil or lubricant around a system to lubricate and cool a bearing arrangement. This action is due to the internal design of the bearing. Different degrees of lubrication and cooling are required depending on the operating conditions of a bearing. At low speed or load, lubricant is primarily used for lubricating the bearings, so a relatively small amount is required. At high speeds or load conditions, the lubricant also acts as a coolant for the system. Therefore, a far greater flow of lubricant is required at high speeds or load conditions.

The pumping action of the spherical roller thrust bearing is present wherever the bearings rotate. Accordingly, if sufficient oil is provided for high load applications, a great deal of energy is wasted pumping excess lubricant around the system at low speeds or loads.

According to a second aspect of the present invention there is provided a bearing arrangement comprising a bearing and a self regulating lubrication system, the lubrication system having a working lubricant reservoir in which the bearing is partially submerged, and a return lubricant reservoir in fluid communication with the working lubricant reservoir by means of a passageway, wherein the passageway restricts the flow of lubricant from the return reservoir to the working reservoir to control lubricant flow around the system.

Further features of the invention are provided as recited in any of claims 8 to 15.

The bearing may be a spherical roller thrust bearing.

The passageway is adapted to restrict the flow of lubricant because of the lubricant viscosity. As the temperature of the lubricant rises its viscosity decreases, and increased flow is possible. Therefore, the arrangement advantageously provides minimal lubricant flow at minimal bearing loads, and increased lubricant flow in increased load conditions.

By tuning the various characteristic dimensions of the flow passageway (length and/or diameter) and/or the number of flow passageways provided, a self-regulating system is obtained for a variety of applications. The physical characteristics of the lubricant system can be determined from suitable equations.

Bearing assemblies are commonly mounted in relatively small housing areas with little or no airflow. In high load applications in particular, this prevents problems with overheating of the bearing arrangements. To counteract this, it is not uncommon to provide cooling jackets in the bearing arrangement, or to employ large fans to forcibly cool the assembly. These have limited effect due to the enclosed nature of the housing, and place unnecessary drains on the systems power supply.

According to a further aspect of the present invention there is provided a system, comprising a bearing arrangement mounted in a housing between first and second apertures provided in the housing, wherein the bearing arrangement is mounted to a mounting element of the housing by protruding sections to allow airflow between the first and second apertures to cool the bearing arrangement.

The open nature of the system greatly increases airflow around the assembly, reducing the need for other forms of cooling.

Further features of the invention are provided as recited in any of claims 17 to 22.

Ideally the natural free convection within the system allowed by the apertures will be sufficient to cool the bearing arrangement. Where forced convection is employed, for example by the provision of a fan, this is advantageously applied in the same direction as the free convection.

Any fan provided may advantageously be disposed on a driver shaft supported by the bearing arrangement, and is ideally selectively operable, perhaps in response to the temperature of the overall system.

The above aspects are not intended to be mutually exclusive. It should be noted that a system according to the first and/or third aspect of the invention could incorporate a bearing arrangement according to the second aspect. This may indeed be the most preferable solution to the stated problem. Alternatively, the first and third aspects may be combined without the second aspect.

Embodiments of the invention will now be described with reference to the accompanying drawings.

The drawings and their description are included by way of example only, and are not intended to limit the protection sought. In the drawings: Figure 1 is a view of a system according to the present invention; Figures 2a-2d show the process of removal of a bearing arrangement and a seal element form the system of Figure 1; Figure 3 shows a bearing arrangement according to a second aspect of the present invention; Figure 4 is a view of the bearing arrangement of Figure 3, with arrows showing lubricant flow around the system; Figure 5 shows a system according to a third aspect of the present invention; and

Figure 6 shows a prior art system.

Figure 1 shows a system 1 according to the present invention. In this particular embodiment the system 1 shown is that of a vertical turbine water pump, and comprises a compact bearing arrangement 2, a housing 3, and a rotating shaft 4 supported by the bearing arrangement 2 and having a spacer coupling 6, which is removable to provide a discontinuity in the rotating shaft 4. The bearing arrangement 2 is removably mounted to a mounting element 8, in this case an internal flange of the housing 3, on the side of the flange 8 adjacent the spacer coupling 6.

An aperture 10 is provided in the housing 3 in the region of the spacer coupling 6 to allow access to the spacer coupling 6 and to the bearing arrangement 2. The aperture is of the type already known in this application to enable removal of a seal element 12 from the system I without needing to dismantle the housing 3 from the top down.

The rotating shaft 4 in this application is vertical but there is no reason why the invention could not be applied to a horizontal shaft, or an angled shaft. The bearing arrangement 2 is shown mounted above the spacer coupling 6, with the seal element 12 below, although alternative arrangements are also possible. It is, however, preferable that the bearing arrangement and sealing element are positioned on the opposite sides of the spacer coupling.

The arrangement as shown allows improved access to internal components of the system 1, such as the bearing arrangement 2 and the sealing element 12. The spacer coupling 6 and aperture 10 allow components to be removed from the middle of the system without dismantling the housing 3.

Figures 2a to 2d illustrate the removal of a bearing arrangement 2 and a seal element 12 from the water pump system 1 of Figure 1. The complete assembled system I is shown in Figure 2a. Figures 2b and 2c show the removal of the spacer coupling 6 to provide a discontinuity in the rotating shaft 4. Finally, Figure 2d shows the removal of the bearing arrangement 2 and the seal element 12.

It should be noted that all components are removed through a common aperture 10, without the need to dismantle the water pump.

Figure 3 shows a bearing arrangement 2 according to a second aspect of the present invention. The bearing arrangement 2 comprises a spherical roller thrust bearing 14, and a self-regulating lubrication system. The lubrication system has a working lubricant reservoir 16 in which the bearing 14 is partially submerged, and a return lubricant reservoir 18, connected by a passageway 20 to the working lubricant reservoir 16, wherein the passageway 20 restricts the flow of lubricant from the return reservoir 18 to the working reservoir 16 to control lubricant flow around the system.

The passageway 20 permits minimal lubricant flow when the bearing arrangement 2 is under minimal load (cold system); and maximum flow when the bearing arrangement 2 is under maximum load (hot system). This is as a result of the change in viscosity of the lubricant as the temperature of the system increases.

Figure 4 shows a view of the same bearing arrangement with arrows provided to indicate the direction of the lubricant flow around the system.

It may be that more than one passageway 20 is provided. The number of passageways 20, their length I, and their diameter d, may be varied to obtain the required lubricant flow for a given application.

The physical parameters of the lubricant system are preferably determined based on required lubricant flow rates, using one or both of the following equations.

pd4H e pd4H e Q,= / 0.00063K1 0.00063K,,! Where Q' is the total circulating lubricant flow for the cold system, Qh' is the total circulating lubricant flow for the hot system, Ks' and Kh' are the kinematic viscosities of the lubricant at cold ( 0 C) and hot ( 80 C) temperatures respectively, measured in Centistokes. p' is the number of passageways 20, I' is their length in feet and d' their diameter in inches. H1' is the difference in oil level between the working reservoir 16 and the return reservoir 18 in feet, and e' is an empirical adjustment factor, To obtain an arrangement that is suitable for both cold and hot conditions, Q should be greater than the minimum required lubricant flow for lubrication only, and Oh should be less than the maximum lubricant flow for lubrication and cooling.

Figure 5 shows a system 1 according to a third aspect of the present invention. The system i is identical to that shown in Figure 1, and comprises a bearing arrangement 2 mounted in a housing 3 between first and second apertures 10,22 provided in the housing 3, wherein the bearing arrangement 2 is mounted to a mounting element 8 of the housing 3, in this instance an internal flange, by protruding sections 24 to allow airflow between the first and second apertures 10, 22 to cool the bearing arrangement 2. Arrows are included in Figure 5 to indicate the passage of air around the system.

Preferably the airflow is generated by free convection. In the shown example the heat generated by various parts of the system warms the air causing it to rise up past the bearing arrangement 2 and out of the top aperture 22. As a result more cold air is drawn into the bottom aperture 10.

A system shown also includes a fan 26 to generate additional forced convection. The fan 26 is mounted on a driven shaft 4 which is supported by the bearing arrangement 2.

The fan 26 preferably acts to force air in the direction of any free convection already present in the system. A thermostat (not shown) is included to allow operation of the fan 26 to be controlled based on the temperature of the system 1.

Figure 6 is included for reference only, and shows a prior art version of a vertical turbine water pump. The bearing arrangement 2a is mounted to a shelf 8a in a small upper chamber of the housing 3a. No great airflow is possible and, accordingly, a cooling jacket 28 is incorporated into the bearing arrangement 2a to provide sufficient cooling. The resulting bearing arrangement 2a is, therefore, quite large. No spacer coupling is provided in the shaft 4a, and the apertures lOa,22a in the housing 3a are relatively small. As a result, access to the internal components of the system is limited without resorting to dismantling the housing 3a.

The present invention addresses all of the above problems to provide a more efficient bearing arrangement, and a more accessible, easily maintained system.

The invention is not limited to the particular embodiment described above, but is intended to cover variations reasonably apparent to a skilled reader. For example the layout, orientation, or predse nature of the various components mentioned above could be varied without departing from the Inventive concept outhned.

Claims

CLAIMS.

1. A system comprising a compact bearing arrangement, a housing, and a rotating shaft, supported by the bearing arrangement and having a spacer coupling, removable to provide a discontinuity in the rotating shaft, wherein the bearing arrangement is removably mounted to a mounting element of the housing on the side of the mounting element adjacent the spacer coupling.

2. A system according to claim 1, wherein the mounting element is an internal flange of the housing.

3. A system according to claim I or 2, wherein the housing is provided with an aperture in the region of the spacer coupling.

4. A system according to any of the preceding claims, wherein the rotating shaft is vertical.

5. A system according to claim 4, wherein the bearing arrangement is mounted above the spacer coupling.

6. A system according to any of the preceding claims, further comprising a sealing element positioned around the rotating shaft on the opposite side of the spacer coupling from the bearing arrangement.

7. A bearing arrangement comprising a bearing and a self regulating lubrication system, the lubrication system having a working lubricant reservoir in which the bearing is partially submerged, and a return lubricant reservoir in fluid communication with the working lubricant reservoir by means of a passageway, wherein the passageway restricts the flow of lubricant from the return reservoir to the working reservoir to control lubricant flow around the system.

8. A bearing arrangement according to claim 7, wherein the passageway permits minimal lubricant flow when the bearing arrangement is under minimal load, and maximum flow when the bearing arrangement is under maximum load.

9. A bearing arrangement according to claim 7 or 8, wherein more than one passageway is provided.

10.A bearing arrangement according to claim 9, wherein the number of passageways is selected to obtain the required lubricant flow.

11.A bearing arrangement according to any of claims 7 to 10, wherein the length of the or each passageway is selected to obtain the required lubricant flow.

12.A bearing arrangement according to any of claims 7 to 11, wherein the diameter of the or each passageway is selected to obtain the required lubricant flow.

13.A bearing arrangement according to any of claims 7 to 12, wherein the physical parameters of the lubricant system are determined based on required lubricant flow rates, using the equation pd4H e C 0.00063K1

14.A bearing arrangement according to any of claims 7 to 13, wherein the physical parameters of the lubricant system are determined based on required lubricant flow rates, using the equation pd4H e -0.00063K,,!

15.A bearing arrangement according to any of claims 7 to 14, wherein the bearing is a roller thrust bearing.

16.A system, comprising a bearing arrangement mounted in a housing between first and second apertures provided in the housing, wherein the bearing arrangement is mounted to a mounting element of the housing by protruding sections to allow airflow between the first and second apertures to cool the bearing arrangement.

17.A system according to claim 16, wherein the mounting element is an internal flange of the housing.

18.A system according to claim 16 or 17, wherein the airflow is generated by free convection.

19.A system according to any of claims 16 to 18, wherein the airflow is generated by forced convection.

20.A system according to claim 19, further comprising a fan on a driver shaft supported by the bearing arrangement.

21. A system according to claim 20, wherein the fan is selectively operable.

22.A system according to claim 21, wherein the fan is controllable based on the temperature of the system.

23.A system substantially as hereinbefore described, with reference to Figures 1 and 2 of the accompanying drawings.

24.A bearing arrangement substantially as hereinbefore described, with reference to Figures 3 and 4 of the accompanying drawings.

25.A system substantially as hereinbefore described, with reference to Figure 5 of the accompanying drawings.