Title of Invention	A CIRCULATION PUMP A DOUBLE SPIRAL HOUSING
Abstract	A circulation pump comprising of: a housing in the manner of a double spiral the said housing includes a housing lip defining the outlet passage, a rib configured as a dividing wall disposed in the said housing, characterised in that the said rib is made at least bipartartite spaced from each other to form one or more gaps between the rib parts.

Full Text

-2- This invention relates to a circulation pump a double spiral housing. The invention relates to a circulation pump having a housing in the manner of a double spiral and a rib configured as a dividing wall disposed therein. In circulation pumps there is known to be a hydraulic radial force produced by the interaction of the impeller and the pump housing. Such radial forces are subject to various influences such as those described for example in KSB-Kreiselpumpenlexikon, 3rd Edition, 1989, pages 242 and 243. Single spiral housing pumps have in the design point along the impeller circumference a virtually constant pressure or velocity distribution. At this point a spiral housing pump can be operated virtually free of radial force. If, however, a spiral housing pump is operated at partial load or overload due to changed conditions of operation, this leads to increasing radial forces due to varying pressure or velocity distributions along the impeller circumference. This disadvantage has led to the development of double spiral housings, as disclosed for example in US-A-2,95,540, and in which the radial forces are at a low level over the entire operating range. A double spiral housing consists of two spiral halves offset by 180° in which a fluid flowing from the impeller is collected and fed to a common discharge connection. On account of the quasi mirror-image arrangement of the two spiral halves, an approximately symmetrical pressure distribution develops along one impeller circumference, whose resultant components of force cancel one another. A double spiral housing is created by inserting into a single spiral housing a so-called "rib" as a dividing wall which, as seen in the direction of impeller rotation forms a second half spiral about 180° behind a lip of the housing. The side of the rib facing away from the impeller, the rear side, defines a diversion channel through which a fluid that has collected in the first spiral half is guided to the discharge connection. The manufacturing of double spiral housings is technically complex and expensive, since the long housing cores necessary for casting are troublesome to secure so that they will not float up during the casting process. After the casting is complete the removal of the cores offers considerable difficulty in cleaning up the casting. For this purpose, additional holes are often provided in the pump housing wall but it is difficult to weld them shut so as to withstand pressure. Despite these measures, the hard-to-reach areas of the double spiral housing allow -3- only an incomplete surface treatment, the consequence of which is a loss of efficiency. To avoid these disadvantages, it is known from US-A-2,955,540 to make the rib as a separate part and insert it afterward into a cast spiral housing. This does facilitate machining the surface to dress the casting, but it requires a great amount of work in the production of a double spiral housing, so that there is no cost advantage. For this reason much research has been conducted toward a critical study of the geometry of the ribs of double spiral housings and to examine their radial force curves. It is known, for example, from US-A-3,289,598 that by varying the length of the rib and the looping angle of this rib a change in the radial force curve can be obtained. In Fig. 7 of US-A-3,289,598 the radial force curves of modified ribs are shown. Shortening gives but an insignificant improvement in manufacture and has the additional disadvantage that such shortening entails an increase in the radial forces in the partial-load and overload range. The invention is therefore addressed to the problem of developing a double spiral housing which will combine simpler manufacture, especially simpler casting procedure, with a good spiral force curve. The solution of this problem provides for the rib to be made at least bipartite, and to have one or more gaps between its parts. This permits problem-free production of a double spiral housing whose cross section can be freely designed. The known rectangular, trapezoidal, pear-shaped spirals, etc., can easily be applied. Making the rib a multipartite component consisting of at least two rib parts placed at a distance apart and forming a gap permits a simple placement of the rib parts within the spirals and evens out the pressure distribution along the runner circumference. Furthermore, an improved radial force curve is thereby achieved in comparison with a single spiral housing. Thus, the radial force in the entire load range of the pump can be reduced. The arrangement of the rib parts at a distance apart creates a gap between them so that the complex additional supports for a casting core can be dispensed with. This has the advantage that it makes the paths of flow near the rib parts much easier to reach when cleaning up the casting. According to one embodiment of the invention, accessibility can be further improved if the rib part opposite a lip in the housing is disposed at a distance from it to form a gap. This improves accessibility to the flow passages created thereby in the area of the rib parts forming the double spiral. -4- Another embodiment of the invention provides that the looping angle f of a rib part in relation to the number n of the rib parts used is in the range of It is then sufficient that the distance and position of the rib parts in relation to one another is adjusted so that access to the passages defined by the rib parts is assured by the gaps existing between the rib parts and between rib part and housing lip. For this purpose the distance between the upstream edges of the rib parts is adjusted such that sufficiently large gaps will be formed by the rib parts. The difference in the angles of the rib parts, AT, corresponds to the condition The profiles of the rib parts can be of equal or different shape, the rib length having no influence, due to the reference to the upstream edges of the buckets. It has proven advantageous toward a further reduction of the radial forces if the upstream edges of the rib parts are disposed on circles with the diameter Dr, whose ratios to the runner diameter D2 are in the range of The profiles of the rib parts can be of equal or different shape, the rib length having no influence, due to the reference to the upstream edges of the buckets. It has proven advantageous toward a further reduction of the radial forces if the upstream edges of the rib parts are disposed on circles with the diameter Dr, whose ratios to the runner diameter D2 are in the range of -5- The diameters on which the upstream edges of the individual rib parts are placed need not be identical; instead the upstream edges of the rib parts can be on different diameters. According to an additional embodiment of the invention the radial forces are advantageously also reduced by disposing the upstream edge of one of the rib parts always on a smaller diameter than one end of a rib part situated ahead of it in the direction of flow. The spiral housing is, of course, so configured that the channel defined by a rib part does not hamper or disadvantageously affect the exit of the fluid from the first spiral part. The profile of the rib parts is subject to no limitations. Rib parts of constant thickness or also with a given thickness distribution can be used. Likewise it is possible for the rib parts to have different shapes. Such configuration of a rib provides for a very easy production of a double spiral housing by Casting. At the same time it offers the advantage that such rib parts can also easily be added on afterward. An additional possibility is an adjustable arrangement of the rib parts. Depending on how the shaft is arranged on the double-rib part, the angle of attack of the latter can be varied with respect to the flow issuing from the runner. A positive effect on the reduction of the radial force is also obtained by making the cross-sectional area in the first quadrant of the double spiral housing after the housing lip larger than a normal spiral development. It has been found that, by such measures a radial force curve can be achieved that will correspond approximately to the radial force curve of a conventional double spiral housing. The slight differences, however, are negligible since the advantages achievable by the simpler production far outweigh it. Embodiments of the invention are represented in the drawings and are described herein. Figs. 1 and 2 show different embodiments of the multipartite double spiral rib. -6- In Fig. 1 is shown a housing 1 of a circulation pump in which the outside diameter D2 of a runner is represented. The housing 1 is configured, as a double spiral housing, the first portion 3 of a spiral starting at the lip 4 of the housing. The housing lip 4 lies in this case in the first quadrant in which a discharge connection 5 is also situated. The first spiral portion 3 has an increasing enlargement of cross section, which in this example reaches its maximum at the end of the second quadrant. From this point a fluid is driven through a bypass 6, 7, to the discharge connection 5. The bypass 6, 7, is defined by the wall of the housing 1 as well as the wall of the rib parts 8 and 9 which are used in this case. These rib parts 8 and 9 form the other or second spiral portion, in a manner similar to a double spiral housing. A gap 10 between the rib parts 8 and 9, as well as a gap 11 situate between the housing lip 4 and the end of the rib part 9, make possible an access to the passages 6 and 7 during production of the housing. Thus, for example, in the case of a cast housing, a housing core used therein can easily be removed and the casting surface can be cleaned up. Thus the surfaces carrying the current can be given a roughness by means of which the efficiency of such a pump housing can be improved. The rib parts 8 and 9, here represented, can have a constant thickness d or, as shown, can be provided with an identical or different bucket profile. Rib part 8 in this embodiment is represented longer than rib part 9. The location of the first rib part 8, in the direction of flow with respect to the housing lip 4 in the first quadrant is determined by the angle x. This angle t is found by formula (2). By means of the formula (1) given, the looping angle (j) of the number (n) of rib parts 8 and 9 used in accord with the application can be determined. The space AT represented in Fig. 1 between the upstream edges 12 and 13 of rib parts 8 and 9 is defined by Formula (3) above. The upstream edges 12 and 13 of rib parts 8 and 9 lie on circles with a diameter DD whose ratios to the runner diameter D2 according to Formula (4) is in the range of Fig. 2 shows the rib parts 8 and 9 in a different kind of arrangement than Fig. 1. The rib part 8 disposed in the 3rd quadrant of housing 1 is here made shorter, while rib part 9 in the 4th quadrant has a greater length. A positive influence on lowering the radial force is also -7- provided by a measure that is here represented in the first quadrant of housing 1. An enlargement of the spiral cross section that takes place in this area, which is greater than in a normal spiral development, is here represented by a broken line. Also the housing lip 4 is at a greater distance from the outside diameter D2 of a runner. The cross-sectional enlargement 14 in the first quadrant of the spiral housing, and the position of the rib parts 8 and 9 in relation to one another and to the housing lip 4 is adapted to the hydraulics of the particular application of a runner and the particular spiral shape. Thus radial force reductions can be achieved which correspond to the radial force characteristic of a traditional double spiral configuration. The radial force characteristic can also be influenced by means of variations with respect to the position of the upstream edges 12 and 13, the shape and the size of the rib parts 8 and 9. -8-WE CLAIM 1. A circulation pump comprising of: a housing (1) in the manner of a double spiral the said housing (1) includes a housing lip (4) defining the outlet passage, a rib configured as a dividing wall disposed in the said housing, Characterised in that the said rib is made at least bipartartite spaced from each other to form one or more gaps (10) between the rib parts (8,9). 2. Circulation pump as claimed in claim 1, wherein the rib part (9) opposite a housing lip (4) is disposed at a distance therefrom to form a gap (11). 3. Circulation pump as claimed in claim 1 or 2, wherein the loop angle (4) of a rib part (8,9) depending on the number n of rib parts (8,9) used is in the range of 4. Circulation pump as claimed in claim 1, 2 or 3, wherein the angular position (x) of the first rib part (8) seen in the direction of flow with respect to the housing lip (4) is in the range of 5. Circulation pump as claimed in any one of claims 1 to 4, wherein an angle difference t between the upstream edges (12, 13) of the rib parts (8,9) defining the magnitude of the gaps (10,11) corresponds to the formula 6. Circulation pump as claimed in any one of claims 1 to 5, wherein the upstream edges (12,13) of the rib parts (8,9) are disposed on circles of equal or different diameters (Dr). -9- 7. Circulation pump as claimed in claim 6, wherein the ratio of the diameters D, to the runner diameter D2 is in the range of 8. Circulation pump as claimed in any one of claims 1 to 7, wherein an upstream edge (13) of a rib part (8,9) is disposed on a smaller diameter than one end of a rib part (8) situated ahead, in the direction of flow, of an upstream edge (13). 9. Circulation pump as claimed in any one of claims 1 to 8, wherein the rib parts (8,9) have and equal and/or profiled cross section. 10. Circulation pump as claimed in any one of claims 1 to 9, wherein the rib parts (8,9) are disposed adjustably in the double spiral housing. 11. Circulation pump as claimed in any one of claims 1 to 10, wherein in the first quadrant I of the double spiral housing, starting from the housing lip (4), a cross-sectional area enlargement (14) takes place. A circulation pump comprising of: a housing in the manner of a double spiral the said housing includes a housing lip defining the outlet passage, a rib configured as a dividing wall disposed in the said housing, characterised in that the said rib is made at least bipartartite spaced from each other to form one or more gaps between the rib parts.

Documents:

01120-cal-1998 abstract.pdf

01120-cal-1998 claims.pdf

01120-cal-1998 correspondence.pdf

01120-cal-1998 description(complete).pdf

01120-cal-1998 drawings.pdf

01120-cal-1998 form-1.pdf

01120-cal-1998 form-2.pdf

01120-cal-1998 form-3.pdf

01120-cal-1998 form-5.pdf

01120-cal-1998 pa.pdf

01120-cal-1998 priority document.pdf

1120-cal-1998-granted-abstract_.pdf

1120-cal-1998-granted-acceptance publication_.pdf

1120-cal-1998-granted-claims_.pdf

1120-cal-1998-granted-correspondence_.pdf

1120-cal-1998-granted-description (complete)_.pdf

1120-cal-1998-granted-drawings_.pdf

1120-cal-1998-granted-form 1_.pdf

1120-cal-1998-granted-form 2_.pdf

1120-cal-1998-granted-form 3_.pdf

1120-cal-1998-granted-form 5_.pdf

1120-cal-1998-granted-letter patent_.pdf

1120-cal-1998-granted-pa_.pdf

1120-cal-1998-granted-priority document_.pdf

1120-cal-1998-granted-reply to examination report_.pdf

1120-cal-1998-granted-specification_.pdf

1120-cal-1998-granted-translated copy of priority document_.pdf