Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
  • F04D29/00—Details, component parts, or accessories
  • F04D29/40—Casings; Connections of working fluid
  • F04D29/42—Casings; Connections of working fluid for radial or helico-centrifugal pumps
  • F04D29/426—Casings; Connections of working fluid for radial or helico-centrifugal pumps especially adapted for liquid pumps
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
  • F04D5/00—Pumps with circumferential or transverse flow
  • F04D5/002—Regenerative pumps

Definitions

• the present invention relates to an improved pump casing for centrifugal pumps with a particularly simplified structure, which can be obtained by casting, pressure die-casting or by other processes for forming metallic materials such as cast iron, steel, brass, bronze and the like.
• centrifugal or liquid-ring pumps are normally used to raise liquids from shallow wells or to circulate them in small-capacity household systems.
• Such pumps generally have a casing which is defined by a main portion, provided with an axial suction inlet, an approximately radial discharge outlet and a pressure chamber or volute accommodating an impeller with peripheral blades, which is coupled to a secondary portion for the closure of the pressure chamber and connection to an electric motor or the like.
• an accumulation pre-chamber R is defined proximate to the inner end of the suction inlet B; the pre-chamber has a slightly conical toroidal shape and is adjacent to a substantially annular pressure chamber or volute P.
• the accumulation chamber R has a front wall, or partition S at its inner end. Partition S separates chamber R from the pressure chamber P.
• a channel C extends between the upper region of the accumulation chamber, externally with respect to the partition, and the pressure chamber or volute, and ensures the continuous filling of the volute.
• the casing has, in the pressure chamber, annular ridges which define front skimming surfaces for the impeller, with axial plays on the order of a few hundredths of a millimeter. This entails the risk of sticking of the impeller during idle periods, considerable initial separation friction, shorter impeller life and a certain noise.
• the aim of the present invention is to eliminate, or at least considerably limit, the above described problems by providing a pump casing with simplified structure, obtainable by pressure die-casting or by means of other methods for forming metallic materials, which allows to considerably reduce its manufacturing costs.
• An object of the present invention is to provide a centrifugal pump casing which is lighter and more compact than conventional ones.
• Another object is to provide a pump casing which has less risk of impeller sticking and lower initial separation friction and furthermore has a self-cleaning effect on the impeller.
• Not least object of the present invention is to provide a method for the simplified manufacture of the above described pump casing.
• a pump casing for centrifugal pumps which can be obtained by casting, pressure die-casting or by another process for the forming of a metallic material, comprising an axial suction inlet connected to a pressure chamber shaped as an annular volute, a centrifugal impeller being arranged in said pressure chamber, said pressure chamber being provided with a radial discharge outlet, characterized in that said suction inlet has a substantially radial peripheral passage and an axial channel at the region where it is connected to the pressure chamber both said peripheral passage and said axial channel being connected to the pressure chamber and being obtained by means of a single core (F) which forms both said suction inlet and said chamber.
• F single core
• the casing can be produced by using a single forming core instead of two as in the prior art.
• the casing has, along the edge of the axial channel, a first axial ridge which forms a front skimming surface for the impeller and defines, together with the non- bladed surface of the impeller, an element for separating the axial channel from the volute.
• Said casing furthermore has, on the portion for connection to the motor, a second axial ridge which forms a further front skimming surface for the impeller, at least one of said ridges being interrupted by a radial groove which forms a passage between the suction inlet and the volute.
• a method for the production of castings or pressure die-castings of casings for centrifugal pumps wherein a single core is adapted to define both the suction inlet and the pressure chamber which are mutually connected by means of a substantially radial peripheral passage and an axial channel.
• Figure ! is a partially sectional side view of a pump casing of the prior art, taken along an axial vertical plane;
• Figure 2 is a partially sectional front view of a first embodiment, of the pump casing according to the invention, taken along the transverse plane II-II of figure 3;
• Figure 3 is a sectional side view of the casing of Figure 2, taken along the axial plane III-III;
• Figure 4 is a partially sectional front, view of a second embodiment of the pump casing according to the invention, taken along a transverse plane IV-IV of Figure 5;
• Figure 5 is a partially sectional side view of the casing of Figure 4, taken along the axial plane V-V;
• Figure 6 is a partially sectional general side view of a centrifugal pump which includes the casing of Figures 2 and 3 ;
• Figure 7 is a partially sectional general side view of a centrifugal pump which includes the casing of Figures 4 and 5.
• a pump casing has a main portion 1 and a secondary portion 2.
• the main portion 1 has a suction inlet 3, which is substantially tubular and coaxial to the axis O of the pump, and a discharge outlet 4, whose axis is substantially radial and slightly offset with respect to the axis 0 of the pump.
• Both the suction inlet 3 and the discharge outlet are internally partially threaded to allow coupling to pipes, respectively for feed and discharge, which are not illustrated in the drawings.
• the suction inlet 3 and the discharge outlet 4 are both connected to a pressure chamber which is shaped as an annular volute 5, defined inside the main portion 1 and closed by the secondary portion 2.
• An impeller 6 with peripheral blades is accommodated in the volute 5.
• the pressure chamber 5 is also connected to a secondary chamber 7. Sensors for measuring flow parameters are arranged in chamber 7 which is provided with a passage 8. Passage 8 is internally threaded and open outwardly. The suction inlet 3 is connected to the pressure chamber 5 through an approximately radial passage 9. Passage 9 is slightly inclined toward the discharge outlet and is suitable to convey the fluid toward the impeller 6.
• the secondary portion 2 is fixed to a motor 10 by means of bolts 11 and is provided with seats for a mechanical seal 14 and a bearing 12 of the motor shaft 13.
• the impeller 6 is keyed to shaft 13 and the mechanical seal 14 is arranged within the main portion 1 of the casing.
• the main portion 1 is connected to the secondary portion 2 by inserting the peripheral edge of main portion 1 in an annular seat 15 of the secondary portion 2, and by means of connecting bolts 16 which are inserted in through holes 17 of the two portions.
• the suction inlet 3 is provided with an axial channel 18 which is connected to the pressure chamber 5.
• the radial passage 9 and the axial channel 18 can be obtained by means of a .single core F which extends uninterruptedly from the pressure chamber to the suction inlet and to the discharge outlet and is schematically indicated in broken lines in Figure 3.
• An annular ridge 19 is provided along the edge of the opening 18 and has a front surface 20.
• Front surface 20 forms an axial skimming surface for the impeller and cooperates with the non-bladed part thereof to separate the axial channel from the volute-shaped pressure chamber 5.
• the connecting portion 2 of the pump body has a similar annular ridge 21.
• the front surface 22 of ridge 21 also forms a radial skimming surface for the impeller.
• Two partially radial curved wings 23 and 24 also extend from both ridges.
• the two annular ridges 19' and 21' are interrupted by respective radial grooves 25 and 26 which define corresponding passages between the suction duct 3' and the pressure chamber 5' .
• skimming surface 20' and 22" of each ridge 19' and 21' is interrupted at the side of the corresponding wing 23' and 24' which interrupts the continuity of the volute 5.
• the fluid is then redirected from an axial direction to a radial direction until it enters the volute and is centrifuged by the set of blades until it exits through the discharge duct 4'.
• the interruption of the skimming surfaces 20' and 22' reduces, in percentage terms, the region of possible impeller sticking.
• the motor is thus less stressed during startup, and initial separation friction is also smaller. Longer impeller life is thus also obtained.
• a single casting channel for a cluster of castings which comprises for example at least four parts.
• a plurality of clusters can furthermore be arranged in the same casting box, for example four clusters arranged uniformly so as to optimize the process and reduce preparation and casting times.
• the pump casing according to the invention achieves the intended aim and objects, and in particular the considerable constructive simplification of the semifinished parts, the significant reduction in the costs for the production of the semifinished parts and of the cores and the better operation and longer life of the pump are stressed.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Structures Of Non-Positive Displacement Pumps (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=11424744

Family Applications (1)

Country Status (5)

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Family Cites Families (2)

• 1991
  • 1991-09-27 IT ITVI910154A patent/IT1253353B/it active IP Right Grant
• 1992
  • 1992-09-24 AU AU26467/92A patent/AU2646792A/en not_active Abandoned
  • 1992-09-24 HU HU9400897A patent/HU9400897D0/hu unknown
  • 1992-09-24 EP EP92920612A patent/EP0605579A1/en not_active Ceased
  • 1992-09-24 WO PCT/EP1992/002211 patent/WO1993006372A1/en not_active Application Discontinuation

Non-Patent Citations (1)

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