GB1589364A - Axial flow pumps - Google Patents

Description

(54) AXIAL FLOW PUMPS (71) We, SIGMUND PULSOMETER PUMPS LIMITED, a Company registered under the laws of England, of Oxford Road, Reading RG3 1JD, Berkshire, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to pumps, more particularly but not exclusively for the extraction of ground water from bore hole wells.

According to the present invention a pump module comprises a pipe, a shaft supported in the pipe by a bearing assembly, and an axial flow impeller mounted on the shaft for rotation therewith, the pipe and the shaft each being adapted at the ends thereof for attachment to adjacent like pump modules, one end of the pipe being in the form of a socket and the other end in the form of a spigot which can fit into the socket end of the pipe of a like module, whereby a multi-stage pump can be built up including a plurality of such modules connected end to end.

The opposite ends of the module have a complementary spigot and socket configuration such that the one end (e.g. male) of one module may be attached to the other end (e.g. female) of a second like module, and the female end of the first module attached to the male end of a third like module, and so on.

The connection between the modules may be achieved in various ways. As regards the pipes, a flexible locking strip inserted into a path defined by shoulders of the interfitted male and female ends of the pipes of adjacent modules has been found satisfactory. Alternatively, this could be a screwthread connection. As regards the shafts, adjacent ends may be connected together by a suitable form of coupling, e.g. a screw coupling or an interfitting dog-and-notch type of coupling, preferably providing some flexibility.

There may be a bearing assembly at one end or at each end of each module. Each bearing assembly provides radial support for the shaft, whilst in one embodiment of the invention at least one bearing assembly of each module takes thrust loadings also. The bearing assemblies may be mounted in the pipes of the modules by radially extending vanes. In cases where a module has only one bearing assembly the impeller and the vanes respectively may be disposed at opposite ends of the module, the impeller being located on the shaft at or adjacent the point where coupling to the shaft of the next module is made.Thus in such a case the bearing assembly of one module will, in the multistage pump, be disposed close to the impeller of the adjacent module to provide radial and thrust support for that impeller even though the bearing assembly of that impeller's own module is at the other end of that module, thereby avoiding the need for more than one bearing assembly per module. In cases where there are two bearing assemblies per module, one at each end, one of these may be located close to the impeller and provide radial and thrust support, while the other may provide radial support only.

The pipe may be constructed of glassreinforced plastics material and the impeller may be moulded of a similar or different plastics material.

The invention also relates to a pump comprising a plurality of such modules assembled end to end together with a prime mover disposed so as to impart a rotation to the shaft and impeller of each module.

Although the primary purpose of the pump is for extraction of ground water from shallow bore hole wells (e.g. 40-60 feet static head), a pump constructed from the modules as defined above could have other applications in domestic and industrial water supply and if it is constructed of non-corrodible materials it could be particularly suitable for handling certain corrosive waters or waters with corrosive contaminants. The sugar and food industries and the like may also provide circumstances of use where such a pump is advantageous or appropriate.

Up to now the pumps used for shallow well operations have been shortened versions of the type of pump designed for deep well pumping operations (e.g. static head of up to 1000 feet). Use of a pump constructed from modules as defined above for shallow well pumping offers a number of advantages.

These pumps can, for example, provide a stability of flow over rclatively large changes in the level of the water table; the diameter of the well bore tube can be near that required to yield an appropriate flow; the modules can be light in weight which can simplify and cut the cost of transport and on-site handling; non corrodible materials can be used for a standard range of pumps regardless of particular pumping circumstances; and assembly can be carried out largely with unskilled labour.

As each module of the pump has its own impeller which lifts the water only to the impeller of the next higher module, the system works on a rather lower pressure than the prior art type of pump. This is one of the factors that permits use of lighter weight materials than were used beforc. Furthermore, the line shaft driven pumps previously employed had a free run of drive shaft the length of the pump. This entailed certain problems of torque transmission and of supporting the shaft which normally necessitated a large diameter shaft.Alternatively a submersible pump, usually electric, was used which itself entails problems, e.g. of insulation and support. the torque transmitted from top to bottom through the shaft of a pump constructed from the modules of the invention progressively decreases from module to module, in contrast to a conventional pump where the whole of the torque must be transmitted through the full length of the shaft to the submerged pump unit at the bottom, and where stiffness considerations may dictate that a larger shaft diameter is needed than in a pump according to the invention. Also, the fact that the shaft is supported at regular intervals along its length is another factor enabling a small shaft diameter to be used.

The use of an axial flow impeller which exerts its pumping action with a predominantly axial flow in contrast to the predominantly radial flow of a centrifugal impeller, permits the pump to be of substantially uniform diameter throughout its height, which diameter is determined essentially by the desired throughput. The use of radial flow impellers would mean that at the level of each impeller the outside diameter would have to be substantially greater than the diameter of the pipe between stages, so that for a given throughput a bore ho e of larger diameter would be necessary. Conversely, for a given bore hole diameter a pump according to the present invention could provide a larger throughput than a multistage pump employing radial flow impellers.

Other advantages are that the pump need only be selected for flow i.e. cross-sectional area. because due to the modular construction it will automatically generate the desired head with good efficiency, and a small number of basic modular units will cover most flow requirements. Also, if, perhaps due to seasonal variations in ground water table level, the head of the pump alters substantially, e.g. by as much as 10 ft. in a head of 40-60 ft., it would be possible. using a pump constructed from the modules of the present invention either to add to the pump a further module or to remove one of the modules in order to maintain the foot of the pump at an appropriate level for plumping.

The invention may be performed in various ways and an embodiment will now be described, by way of example, with reference to the accompanying drawings in which Figure 1 shows a sectional view through a pump comprising six modules embodying the present invention; Figure 2 shows on a larger scale part of the cross-sectional view between lines A of Figure 1 showing one module and parts of adjacent modules attached to either end thereof; Figure 3 shows on a larger scale a partly sectional view of the pump of Figure 1 inserted in a bore hole; and Figure 4 is a longitudinal section through adjacent portions of two inconnected modules of a modified form.

Referring to Figures 1-3, a pump 10 comprises a number of modules 1 arranged axially end to end, a strainer unit 14 at its lower end, and a discharge head 16 and drive unit 18 at its upper end. In use the strainer unit 14 will be wholly submerged below the level of the ground water table 6, as will also be the lowest impeller of the pump.

Each module 12 comprises a pipe 22 flared slightly at one end 23 to a bell configuration.

The interior of the bell configuration is dimensioned to receive the opposite end 24 of an adjacent module in such a manner that the ends 23 and 24 can be sealed together to form a continuous pipe the length of two (or more) modules.

A bearing assembly 26 is mounted on radial vanes 25 at or near the end 23 of the pipe 22 and a drive shaft 28 is mounted for rotation within the bearing assembly 26. At the end of the drive shaft 28 remote from the bearing assembly there is mounted an axial flow impeller 30 extending substantially to the inner wall of the pipe 22. The shaft 8 is screw-threaded at both ends, each to be joined to the end of the shaft 28 of an adjacent module 12 by screwing it half way into the screw-threaded hub of the impeller 30.

The 'hand' of the screw threads is such that operation of the drive unit 18 in the appropriate sense will tend to tighten the shaft connections. The drive unit 18 will, through the shafts 28, drive all the impellers to cause the ground water to be raised through the modules from the table 6 to the discharge head 16.

The module pipes 22 are connected to one another by means of a locking strip 32 of polymeric material which is inserted endwise through a hole 31 into a groove in the upper, female. end 23 of a module, so that it overlaps an upwardly facing shoulder on the lower, male, pipe end 24 of the adjacent upper module.

Figure 3 shows a pump assembled from the modules of the present invention and installed in a bore hole 4. It will be seen that the effective cross-sectional area through which the ground water is pumped approaches that of the bore hole 4.

The lowermost module 12' and the uppermost module 12" are connected only at their upper and lower ends respectively to other modules 12. Module 12'is connected to the strainer unit 14 and module 12" to the discharge head 16 in a manner corresponding to that described above joining like modules 12. The shaft 28 of module 12' is connected to a bearing assembly 25 within the strainer and the shaft 28 of the module 12" is connected to the power output of the drive unit 18.

The components of the modules 12, where possible, are constructed of or coated with non-corrodible light-weight materials. Thus the pipe may be of a glass-reinforced plastics composite and the impeller may be of an acetal resin, as are the bearing cage and vane assembly, whereas the bearing itself is rubber. For strength it has been found necessary to make the shaft 28 of steel but this can conveniently be rendered non-corrodible by the use of a shaft sleeve (not shown) of stainless steel. These materials can be varied considerably but the general object to be borne in mind is that, within economic bounds, the materials should present non-corrodible surfaces, should be of low density and should not be prone to mechanical failure.

A particular pump embodying the present invention was constructed to meet design requirements of a ground water delivery of 2 cusecs (750 imperial gallons per minute) from a ground water table at approximately 60 ft. below surface, to give a terminal pressure of 0-10 ft. from a drive diesel engine at 850 revolutions per minute maximum. A module 3 metres in length of 150 mm bore was constructed to this end. Such modules can be installed in a 200 mm well bore hole.

Modules 12 of other dimensions can be made to give different flow.

The pump 10 is suspended from the discharge head 16 which is located at ground level 8. The discharge head 16 also serves as a location for the drive unit 18.

Installation of a pump 10 constructed from modules according to the invention may be achieved as follows. The lowermost module 12' is placed horizontally on the ground and the lower end of its shaft 28 is joined to the upper end of the bearing shaft of the strainer unit 14 by rotation in the appropriate sense of the one shaft with respect to the other with the screw coupling threads engaged. The lower end 24 of the lowermost module 12 'is thus inserted in the bell configuration upper end 23 of the strainer unit 14. When fully home a plastics locking strip is introduced into a hole 31 in the strainer unit 14 and forced home into paths formed between shoulders of the mated surfaces of the strainer unit 14 and the lowermost module 1 2 'to lock the units together.There may also be an '0' ring seal between the surfaces of the units to prevent water leakage. The first stage is now ready to be inserted into the bore hole 4 and is lifted to a vertical position from which it is lowered into the bore hole 4 to the point where its end 23 protrudes above the surface of the ground. The next module 12 is then raised into a vertical position and its end 24 fitted into the end 23 of the module 12' as was the lower end 24 of the module 12' fitted to the strainer unit 14. When this next module 12 is fitted into the preceding lower adjacent module 12'the assembly is lowered further into the bore hole 4 and the process is repeated until the complete pump as shown in Figure 3 is assembled. The discharge head 16 is fixed into the uppermost module 12" and the drive unit 18 connected to the combined shaft 28.The discharge head and drive unit are preferably mounted on a concrete base prepared around the opening of the bore hole 4.

Referring now to Figure 4, there is shown the upper end of one module 42 into which is threaded the lower end of the next upper module 43. Fixed in the lower end of the module 43 is a journal bearing assembly 44 comprising a housing 45 supported by radial vanes 46 in the pipe 47 of the module 43. A rubber bush 48 is mounted in the housing 45 and acts as a water-lubricated journal bearing for the shaft 49 of the module 43. Fixed to the lower end of the shaft 49 is a flange 50 carrying a dog 51.

Fixed in the upper end of the module 42 is a journal and thrust bearing assembly 52 comprising a housing 53 supported by radial vanes 54 in the pipe 55 of the module 42. A rubber bush 56 is mounted in the housing 53 and acts as a water-lubricated journal bearing for the shaft 57 of the module 42. Fixed to the shaft 57 above the housing 53 is a member comprising a cylindrical sleeve 58 into which the end of the shaft 57 is screwed and a flange 59 having a notch which receives the dog 51, thereby providing a somewhat flexible driving connection between the shafts 49 and 57. Surrounding and fixed to the sleeve 58 is an impeller assembly comprising a hub 60 carrying impeller blades 61.

Fixed to the lower end of the hub 60 is a ring 62 which cooperates with a ring 63 fixed to the upper end of the housing 53 to constitute a water-lubricated thrust bearing.

WHAT WE CLAIM IS: 1. A pump module comprising a pipe, a shaft supported in the pipe by a bearing assembly, and an axial flow impeller mounted on the shaft for rotation therewith, the pipe and the shaft each being adapted at the ends thereof for attachment to adjacent like pump modules, one end of the pipe being in the form of a socket and the other end in the form of a spigot which can fit into the socket end of the pipe of a like module, whereby a multi-stage pump can be built up including a plurality of such modules connected end to end.

2. A module as claimed in Claim l wherein the ends of the pipe are formed with shoulders to provide a path for insertion of a flexible locking strip when the module is interfitted with a like module.

3. A module as claimed in Claim 1 or Claim 2 wherein one end of the shaft carries a dog and the other end has a complementary notch.

4. A module as claimed in any of the preceding claims having one bearing assembly located adjacent one end of the module and wherein the impeller is mounted adjacent the other end of the module.

5. A module as claimed in any of Claims I to 3 having a bearing assembly adjacent each end thereof.

6. A module as claimed in any of the preceding claims wherein the or each bearing assembly is mounted in the pipe by radially extending vanes.

7. A pump module substantially as described herein with reference to Figures 1 to 3 or Figure 4 of the accompanying drawings.

8. A well pump comprising a plurality of pump modules as claimed in any of the preceding claims connected in end to end relationship, and a prime mover for rotation of the interconnected plurality of shafts and impellers.

9. A pump as claimed in Claim 8 wherein adjacent modules are as claimed in Claim 2 locked to one another by a locking strip introduced into the path between the said shoulders of the interfitted modules.

10. A well pump substantially as described herein with reference to Figures 1 to 3 or Figure 4 of the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (10)

**WARNING** start of CLMS field may overlap end of DESC **. the upper end of the housing 53 to constitute a water-lubricated thrust bearing. WHAT WE CLAIM IS:

1. A pump module comprising a pipe, a shaft supported in the pipe by a bearing assembly, and an axial flow impeller mounted on the shaft for rotation therewith, the pipe and the shaft each being adapted at the ends thereof for attachment to adjacent like pump modules, one end of the pipe being in the form of a socket and the other end in the form of a spigot which can fit into the socket end of the pipe of a like module, whereby a multi-stage pump can be built up including a plurality of such modules connected end to end.

2. A module as claimed in Claim l wherein the ends of the pipe are formed with shoulders to provide a path for insertion of a flexible locking strip when the module is interfitted with a like module.

3. A module as claimed in Claim 1 or Claim 2 wherein one end of the shaft carries a dog and the other end has a complementary notch.

4. A module as claimed in any of the preceding claims having one bearing assembly located adjacent one end of the module and wherein the impeller is mounted adjacent the other end of the module.

5. A module as claimed in any of Claims I to 3 having a bearing assembly adjacent each end thereof.

6. A module as claimed in any of the preceding claims wherein the or each bearing assembly is mounted in the pipe by radially extending vanes.

7. A pump module substantially as described herein with reference to Figures 1 to 3 or Figure 4 of the accompanying drawings.

8. A well pump comprising a plurality of pump modules as claimed in any of the preceding claims connected in end to end relationship, and a prime mover for rotation of the interconnected plurality of shafts and impellers.

9. A pump as claimed in Claim 8 wherein adjacent modules are as claimed in Claim 2 locked to one another by a locking strip introduced into the path between the said shoulders of the interfitted modules.

10. A well pump substantially as described herein with reference to Figures 1 to 3 or Figure 4 of the accompanying drawings.