Patent 3881840 - Centrifugal pump for processing liquids containing abrasive constituents, more particularly, a sand pump or a waste-water pumper
|United States Patent||Patent Number 3,881,840|
|Bunjes||Issued May 6, 1975|
Centrifugal pump for processing liquids containing abrasive constituents, more particularly, a sand pump or a waste-water pumper
A centrifugal pump for processing liquids containing abrasive constituents comprising a housing with a suction opening and a delivery opening and an impeller and having on either side sealing faces located at least partially on the outer side of a sealing slot in which slot, near the entrance side, an annular chamber is formed and means are provided for rotating the liquid in the chamber and near the outer circumference radial, outwardly directed ducts communicate with the annular chamber and open out by a diameter which is smaller than the diameter of the impeller.
|Inventors:||Johan Henri Bunjes (Hengelo NL)|
|Assignee:||Neratoom B.V. (The Hague, NL)|
|Filed:||September 5, 1973|
|Current U.S. Class:||415/109 - 415/111 - 415/1212 - 415/1701 - 415/1711 - 415/1721 - 415/581 - 415/583 - 416/181 - 416/186A - 416/186R|
|Current International Class:||F04D029/08 (20060101)|
|Current CPC Class:||F04D 7/04 (20130101); F04D 29/167 (20130101); F04D 29/2266 (20130101)|
|Field of Search:||415/19T,16T,11T,111T,112T,17AT,172T,113,171,142 277/67,133 417/900 241/55,56,261.3,DIG.5|
|3402671||September 1968||Wilfley et al.|
Assistant Examiner:Louis J Casaregola
Attorney, Agent or Firm:
What I claim is:
1. A centrifugal pump for processing liquids containing abrasive constituents, more particularly, a sand pump or a waste-water pump comprising a housing having a suction opening and a delivery opening and an impeller rotatably arranged in said housing, said housing including an inner sleeve on either side of said impeller and said impeller having a pair of outer sleeves on one side thereof embracing one of said inner sleeves and a further outer sleeve surrounding the other of said inner sleeves, the radially outermost sleeves on opposite sides of said impeller defining sealing slots between said inner and radially outermost sleeves, each outermost sleeve having an annular chamber formed therein and means for rotating the liquid in the chamber, and each outermost sleeve having radial, outwardly, directed ducts communicating with the annular chamber.
2. A centrifugal pump as claimed in claim 1, characterised in that the end face of each outermost sleeve is provided with radial ridges.
3. A centrifugal pump as claimed in claim 2 characterised in that the ridges have inclined contact faces.
4. A centrifugal pump as defined in claim 1 including a second set of radial ducts communicating with each sealing slot and opening out at a larger diameter than the first set of ducts.
5. A centrifugal pump as claimed in claim 4, characterised in that the end of the second set of ducts is located at the end of the main impeller.
6. In a centrifugal pump assembly, the combination of:
a housing having an inlet opening and an annular delivery chamber; an impeller having an inlet eye aligned with said inlet opening and a peripheral portion discharging to said delivery chamber, said impeller and said housing defining an intermediate chamber therebetween leading to said delivery chamber; and
sealing means formed between said housing and said impeller between said inlet opening and said delivery chamber for bleeding liquid from said intermediate chamber to said inlet opening, said sealing means including opposed surface portions of said impeller and said housing defining a sealing slot having an outer end communicating with said intermediate chamber and an inner end communicating with said inlet opening, an annular chamber defined between said surface portions adjacent said outer end of the sealing slot, and duct means in said impeller leading from said annular chamber to said intermediate chamber for redirecting sediment entering said outer end of the sealing slot back into said intermediate chamber, and wherein said surface portions are defined by an outer sleeve on said impeller and an inner sleeve on said housing, said annular chamber being formed in said outer sleeve.
7. In a centrifugal pump assembly as defined in claim 6 including second duct means formed in said impeller and leading from the inner end of said sealing slot to said delivery chamber.
8. In a pump assembly as defined in claim 7 wherein the outer end of said outer sleeve is provided with radially extending teeth.
The invention relates to a centrifugal pump for processing liquids containing abrasive constituents, more particularly, a sand pump or a waste-water pump comprising a housing provided with a suction opening and a delivery opening and comprising an impeller rotatably arranged in said housing and having on either side of the impeller sealing slots formed by relatively co-operating sealing faces of the impeller and of the housing. In such a pump, when working liquids containing abrasive constituents, great wear of the sealing faces will occur so that renewal is frequently required. The invention has for its object to provide such a centrifugal pump, in which said wear is minimized.
According to the invention the sealing face forming part of the impeller and located on either side of the impeller is located at least partly on the outer side of the sealing slot, an annular chamber is formed in the slot near the entrance side, means are provided for rotating the liquid in the chamber and near the outer circumference radially outwardly directed ducts communicate with the annular chamber and open out at a diameter which is smaller than the diameter of the impeller. With such a structure of the centrifugal pump the liquid is freed of the abrasive constituents before it enters the sealing slot because they are separated in the annular chamber from the liquid and discharged through the radial ducts. Since the openings of the radial ducts lie at a smaller diameter than that of the impeller, the liquid will flow through the sealing slot owing to the pressure difference produced by the impeller despite the suction produced in the annular chamber by the radial ducts.
In an effective embodiment the sealing face of the impeller is formed by a thick-walled, tubular impeller portion, within which, near the end, an annular groove is provided and the wall of which has radial ducts communicating with the groove and being partially located at the side of the groove and having the portion of their walls located outside the groove extending into the sealing face. In such an embodiment the means for circulating the liquid in the annular chamber are formed by vanes formed by the fact that the channels are partially located at the side of the annular groove.
According to the invention the end face of the sleevelike portion remote from the impeller may be provided with radial vanes. The liquid flowing towards the annular chamber is thus caused to rotate beforehand, whilst in addition a given amount of pre-cleaning is obtained.
According to the invention this pre-cleaning effect may be enhanced by inclined contact surfaces of the vanes. Thus the lagging impurities in the rotating liquid are slung away in an axial direction.
According to the invention, near the end of the sealing slot remote from the annular chamber, a second set of radial ducts can communicate with the slot, said second set of ducts opening out at a larger diameter than the first set of ducts. It is thus ensured that a larger flow of liquid passes through the sealing slot. It is thus possible to utilize the sealing faces for journalling the pump impeller. In this case it is no longer necessary to hold the pump shaft by bearing located outside the pump-housing, which provides a high gain in space. In high-speed embodiments critical vibrations can be avoided owing to the short shaft.
According to the invention the end of the second set of ducts may be located in the same sectional areas as the ends of the blade channels of the main impeller. Nevertheless a satisfactory flow through the slot is obtained because the subatmospheric pressure produced by the radial ducts exceeds that produced by the main impeller.
According to the invention the stationary face of the sealing slot may be formed by the outer circumference of a sleevelike portion, whose inner side bounds a slot, which is bounded on the other side by a portion rotating together with the impeller, said sleeve-like portion having, near the annular groove, one or more ducts communicative between the two slots. In such an embodiment the end face of the sleeve-like portion may be used as a bearing for absorbing the axial forces. Along this head face clean water is flowing from the annular slot, which is sucked via the ducts through the sleeve-like portion and the slot located on the inner side of the sleeve-like portion.
According to the invention the radial ducts may open out near a shield of the impeller. In such an embodiment accumulation of impurities in the spaces between the pump impeller and the housing is avoided. Near the shields of the impeller the liquid in said spaces is in a strong rotating movement so that near the impeller shields transport in the outward direction occurs. The soil located along the shields of the impeller can be readily conducted away with the liquid in the suction space of the pump .
The invention will now be described more fully with an embodiment shown in the drawing. Therein:
FIG. 1 is an axial sectional view of a pump in accordance with the invention,
FIG. 2 is part of the sectional view of FIG. 1 on an enlarged scale,
FIG. 3 is an axial sectional view of part of the pump embodying the invention in a different form,
FIG. 4 is a sectional view taken on the line IV--IV in FIG. 3 of a further embodiment,
FIG. 5 shows the part of FIG. 4 in an elevation taken on the line V--V,
FIG. 6 is a sectional view taken on the line VI--VI in FIG. 5.
The pump shown in FIG. 1 comprises a housing 1 having a suction opening 8 and a delivery space 3 communicating with a delivery opening (not shown). A shaft 4 is journalled in bearings 5 and 6 and extends through a stuffing box 7 into the housing 1. The shaft holds an impeller 2. The impeller 2 is equipped on either side with sleeve-like portions 9 and 10. The sleeve-like portion 9 grips around a likewise sleeve-like portion 11, which forms part of the housing 1. The sleeve-like portion 10 grips around a sleeve-like portion 12 of the housing. Sealing slots are formed between the portions 9 and 10 and also between the portions 10 and 12. Through said slots a small leakage may occur from the delivery space to the suction side of the pump. A slot 13 is formed between the portion 9 and the portion 11. Near the entrance side of the slot 13 an annular chamber 14 is formed in the sleeve-like portion 9. With said annular chamber communicates radial ducts 15, which are slightly shifted in place with respect to the chamber 14 in an axial direction. The portion of the wall of the ducts 15 opening out at the side of the annular chamber 14 is extended up to the slot 13. These prolonged duct walls form blades in the annular chamber 14. During the rotation of the impeller the liquid in the chamber 14 will be rotated not only under the action of friction but also under the influence of the operation of said blades. In operation liquid will flow, as is indicated by the arrow 16, towards the space 17 between the housing 1 and the impeller 2. In the space 17 excess pressure prevails so that liquid flows from the space 17 through the slot 13 towards the suction side of the pump. This is indicated by the arrows 18 and 19. The liquid entering the slot 13 first arrives inside the chamber 14, where it is subjected to high-speed rotation. As a result impurities will be swept outwardly and be conducted away through the ducts 15. The liquid flowing on through the slot 13 is therefore free of impurities and abrasive constituents. The arrows 44 indicated that a small quantity of liquid with impurities emerges through the ducts 15. The ducts 15 must not open out at too large a diameter, since otherwise a strong suction effect would be exerted on the liquid in the chamber 14 so that the quantity of liquid flowing through the slot 13 would not be sufficient. A slot 20 is formed between the portions 10 and 12. Here again an annular chamber 21 is provided, with which communicate radial ducts 22. A similar activity is performed here as is indicated by the various arrows.
FIG. 3 shows a slightly different embodiment of the pump. It comprises again a housing 1 and an impeller 2. The impeller comprises a sleeve-like portion 23 and the housing 1 comprises a sleeve-like portion 24. A slot 25 is formed between the sleeve-like portions 23 and 24. The portion 26 of the impeller 2 forms the boundary of a slot 27 located on the inner side of the sleeve-like portion 24. At the end face of the sleeve-like portion 24 a slot 28 is formed. Near the entrance side of the slot 25 an annular chamber 29 and radial ducts 30 communicating therewith are provided. Moreover, this embodiment comprises, at the end of the slot 25 remote from the annular chamber 29, a set of radial ducts 31 which communicate with the slot 25 and open out on the outer side at the same diameter as the main impeller 2. Near the annular chamber one or more ducts 32 are provided, which form the communication between slots 25 and 27.
In operation the ducts 31 exert an additional suction force on the liquid in the slots 25, 28 and 27. The liquid flows in the direction indicated by the arrows 33. Like in the embodiment shown in FIG. 1 the liquid entering the chamber 29 is freed of impurities. The liquid having passed through the chamber 29 can directly enter the slot 25 and via the ducts 32 also the slot 27 and be conducted away through the slot 28 towards the ducts 31. In this embodiment it is ensured that an adequate quantity of liquid passes through the slots 25 and 28. It is thus possible to utilize the sleeve-like portions 23 and 24 as bearings for the impeller 2. A similar structure is obtained on the other side of the impeller, where the sleeve-like portion 34 of the housing may serve as a bearing face for the impeller 2. Here a slot 35 is formed in an axial direction and a slot 36 is formed in a radial direction at the end face of the sleeve-like portion 34. Also in this case an annular chamber 37 is available with which communicate the ducts 38. At the other end of the slot 35 ducts 39 open out at the same diameter as the ducts 31. The slot 40 on the inner side of the sleeve-like portion 34 communicates through one or more ducts 41 with the slot 35. In comparison with the embodiment shown in FIG. 1 it is directly apparent that a considerably shorter shaft 4 for the pump impeller can be used. Only a slight space is required for the stuffing box 7. The space required for bearings 5 and 6 can be omitted. FIGS. 4, 5 and 6 show that the end face of the sleeve-like portion 23 is provided with ridges 42 extending in a radial direction and having inclined contact faces 43. The liquid flowing towards the slot 25 and the annular chamber 29 is already set rotating owing to the radial ridges 42 so that a preliminary separation of heavy impurities can take place. Owing to the inclined contact faces the impurities are moved away in an axial direction from the impeller.
FIG. 3 shows that the ducts 38 can be caused to open out in close proximity of the shield of the impeller 2. This has the advantage that the impurities emerging from said ducts can be more readily conducted away to the outside since they get into the zone of the liquid at the side of the impeller where the rotation of the impeller is most effective.
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