GB2121240A - Pump assemblies - Google Patents

Abstract

A pump assembly for heating and faucet water plants, comprises a centrifugal pump having a wet or immersed armature motor, both casings 1, 2 of which are pressed to shape from plate or sheet metal for example and comprise radially outwardly directed and interconnected flanges 1a, 2a between which lie correspondingly radially directed marginal areas 10a, 12a extending encirclingly in flange- like manner of a partition 10 separating the pumping space 8 and the motor space 4, 11 and of a split tube 12 separating the armature space 4 and stator space 11 of the motor. Of the said flanges 1a, 2a and marginal areas 10a, 12a, at least the flanges 1a of the pump casing 1 and the marginal area 12a of the split tube 12 are joined together metal to metal and in hermetic manner, for example by welding or brazing. <IMAGE>

Description

SPECIFICATION Pump assemblies The present invention relates to a pumping assembly for heating and faucet water plants, comprising a centrifugal pump comprising an immersed armature motor the casings of which have interconnected radially outwardly directed flanges between which extend correspondingly radially directed flange-like encircling marginal areas of a partition separating the pumping space and the motor space and of a split tube separating the armature space and the stator space of the motor. Hereinafter such a pumping assembly will be referred to as "of the kind described".

Notwithstanding the fact whether the pump and motor casings are produced from cast or plate metal, such pumping assemblies have some shortcomings associated with the joint between the two casings. This joint is established by bolting together the casing flanges in mutual contact, excessive tightening of the bolt having a tendency to straining of the internally situated components of the assembly, so that the shaft may for example seize in the bearings by skewing.

Apart from the bolts as the actual coupling means, several seals should also be provided between the casing flanges or the marginal areas of the partition and split tube, there normally being three seals which regularly represent a definite risk because they become ineffective in the course of time by compaction and embrittlement and can no longer fulfil their sealing function. Apart from this, it is understandable that the comparatively numerous parts needed for a hermetic joint produced by means of bolts represent a considerable expenditure of overhead and labour costs.

It is an object of the invention to provide a simple joint between the pump casing and the motor casing which remains tight without separate sealing means and which may be made moreover without danger to the other components of the assembly.

To achieve this and other objects, in a pumping assembly of the kind described, of the two flanges of the pump and motor casing as well as of the two marginal areas of the partition and of the split tube, at least the flange of the pump casing and the marginal area of the split tube are joined together metal to metal. This joint may appropriately be produced by welding or brazing.

The strong and hermetic joint between these two parts if of importance primarily because the pump casing and the split tube must form a hermetic and pressure-tight delimitation between the internal volumes of the assembly which are filled with water as the circulated fluid, and the environment.

If no more than the flange of the pump casing and the outer rim of the split tube are interconnected metal to metal, the marginal area of the partition may well be held freely but tightly clamped between these two interconnected parts moreover. The possibility is also available of interconnecting the rim of the partition and, if applicable, also the flange of the motor casing in one operation to the others of the aforesaid parts by means of a single brazing or welding seam encircling the join between the two casings.

If the motor casing is not however intended to be co-encircled by the seam, it may be joined in form-locked manner to the pump casing, if it is arranged to engage in the area of the joint over the welding or brazing seam present thereat and behind the flange of the pump casing.

As already stated in the foregoing, one of the essential advantages of the construction according to the invention consists in that the pump casing and the split tube intended to act as a pressure-tight delimitation between the assembly and the environment are joined together perfectly and hermetically. A breakdown of the assembly caused by compacting or embrittling of seals does not eventuate since separate seals are actually no longer needed. For the same reason, the risk of skewing between the shaft and bearings is thus also precluded in optimum degree.

Not only the seals are omitted moreover, but also separate coupling means such as bolts and the like, thereby allowing of a considerable reduction in the number of components of the pumping assembly depending on design. It should be observed moreover that a pumping assembly in accordance with the invention may be produced in substantially less complicated manner on an automated production line than an assembly where the motor and pump casings have to be bolted to each other. Putting together the components which are to be joined, and the joining operation itself, may as a matter of fact be peformed easily on appropriate automatic machinery.

In order that the invention may be more clearly understood, reference will now be made to the accompanying drawings which show certain embodiments thereof by way of example, and in which: Figure 1 shows a longitudinal cross-section through a pumping assembly in simplified and diagrammatic form and Figures 2 and 3 show longitudinal crosssections through an assembly according to Figure 1 in the area of the circle shown dash-dotted, bub with welded joints produced differently from those in Figure 1.

Referring now to the drawings the pumping assembly shown in Figure 1, which may for example serve the purpose of circulating water in heating and faucet water plants, comprises a centrifugal pump comprising a casing 1 and an electric immersed armature motor comprising a casing 2, the armature or rotor 3 of which revolves within an armature space 4 filled with water.

A shaft 5 is borne by two radial bearings 7 at either side of a stack 6 of armature laminations secured to it. A pump impeller 9 is fastened on the end of the shaft 5 which projects into a pumping space 8.

A partition 10 separates the pumping space 8 and the armature space 4 which for its part is sealed from a dry stator space 11 by means of a split tube 12. A stator stack of laminations 13 and a motor winding 14 secured on the casing 2 are situated in the stator space 11. According to this design, the motor in question is a squirrel-case induction motor.

Pumping assemblies of this nature are generally known in structure and function, so that a more detailed description is not needed and reference will only be made to analogous pumping assemblies which are already known, for example such as those illustrated and described in the German Offenlegungungs Specifications Nos.

2516575,2529399 and 2639540.

The two casings 1,2 the partition 10 and the split tube 1 2 are plate (or sheet) metal pressings.

The two casings have radially directed flanges 1 a, 2a encircling the join, whereas the partition 10 and the split tube 12 also have flange-like radially extending marginal areas 10a, 12a.

In the embodiment according to Figure 1, the flange 1 a and the marginal area 1 2a are joined together by the welding seam 15, the marginal area 1 Oa of the partition being ciamped tight between the sections 1 a and 1 2a without being joined directly thereto.

The casings 1 and 2 are joined together in form-locked manner, such that the motor casing 2 engages with the flange 2a over the welding seam 1 5 in the area of the joint, and behind the flange 1 a.

This connection may be made by simply swageing the casing flange 2a over and by pressing it in around the radially projecting and previously interwelded parts, by means of a tool.

Figure 2 shows a joint which substantially corresponds to that illustrated in Figure 1 and differs from the latter only inasmuch as the marginal area 1 Oa of the partition 10 is also incorporated in the welding seam 1 5. Finally, according to Figure 3, all the flanges 1 a, 2a and marginal areas 1 0a, 1 2a are interwelded hermetically in unitary manner by means of a single encircling welding seam 1 5. This illustrates therefore another possibility.

The essential advantages of this method of construction have already been referred to in the foregoing Another advantage is that the welded joint may comparatively easily be separated again in case the assembly has to be inspected for possible faults and repaired if appropriate.

To this end, only the swaged-over or flattened down section 2b neet merely be expanded again in the joint according to Figures 1 and 2 to allow the casing 2 with the stator elements 13, 14 to be pulled off the split tube 12. The welding seam 1 5 is thereupon removed completely by turning in a lathe, thereby freeing the connection between the casing 1 and the split tube 12 (Figure 1) or that between the casing 1, the partition 10 and the split tube 12 (Figure 2). In the embodiment according to Figure 3, the connection between all four sections 1 a, 2a, 1 Oa and 1 2a may be freed in one operation by removing the welding seam 15 by turning.

For example, to remove the welding seam 1 5 by turning, the pump casing 2 may be churcked in a lathe and the tool is offered up to the welding seam 15. In order that the welding seam may be made freely accessible for the tool, the welding seam should in accordance with the Figures be led along the free outer extremities of the flanges 1 a, 2a and marginal areas 1 0a, 1 2a and extend at a greater radial distance from the longitudinal axis 1 6 than the adjacent axially parallel or cylindrical sections of the pump casing 1 and motor casing 2.

The same said conditions and advantages are evidently also applicable moreover if the parts in question are joined by a brazing seam instead of the welding seam 15.

In conclusion, it is pointed out moreover that pump and motor casings pressed to shape from plate metal allow of uncomplicated and comparatively inexpensive production of the assembly. No problems then arise moreover regarding the joint to be produced by welding or brazing. For example, the motor casing could be produced by injection casting and the pump casing from plate metal, in which case the flange of the pump casing could for example be welded to the marginal area of the split tube, whereas the flanges of the two casings could be joined together by separate components, say by means of clamps, should it prove to be difficult to join a casing of steel plate to a cast iron casing by welding or brazing.

Claims (6)

1. A pumping assembly for heating and faucet water installations, comprising a centrifugal pump comprising an immersed armature motor having casings that comprise interconnected and radially outwardly directed flanges between which are located correspondingly radially directed flange like encircling marginal areas of a partition separating a pumping space and a motor space, and of a split tube separating an armature space and a stator space of the motor, wherein of the flanges and the marginal areas, at least the flange of the pump casing and the marginal area of the split tube are joined together metal to metal.

2. A pumping assembly as claimed in claim 1, wherein the metal to metal joint is produced by welding or brazing.

3. A pumping assembly as claimed in claim 2, wherein the welding or brazing seam is produced along the free outer extremities of the flanges or marginal areas joined together by it, and wherein the seam extends at a greater radial spacing from the longitudinal axis of the assembly than the adjacent sections of the pump casing and the motor casing.

4. A pumping assembly as claimed in claim 3, wherein the motor casing is joined to the pump casing in form-locked manner, the motor casing engaging over the welding or brazing seam present in the area of the joint and behind the flange of the pump casing.

5. A pumping assembly substantially as hereinbefore described with reference to Figure 1 of the accompanying drawings.

6. A pumping assembly substantially as hereinbefore described with reference to Figures 2 and 3 of the accompanying drawings.