Cross-Reference to Related Applications

[001] This application is a non-provisional utility application with a claim of priority to US provisional application 63/136,327, filed on 12 January 2021 , which is incorporated by reference as if fully recited herein.

Technical Field

[002] This disclosure relates to a pump, particularly a pump for use in a basin, having a second impeller, exclusively for circulating a cooling fluid around a motor thereof.

Background

[003] In the prior art, many pumps, and especially submersible-rated pumps, are designed for use with a motor positioned above the impeller, with a vertically- or horizontally-oriented drive shaft. In applications where the pump is deployed in a basin, the pump often has a cylindrical shape around the drive shaft which is longer, having a ratio to axial length to diameter being much larger than a pump that is not intended for a basin. When the pump is substantially submerged, the liquid in which it is submerged can provide a sink for the heat generated by the motor. However, when the motor portion is not substantially submerged or the pump is in continuous dry run, the motor can overheat.

[004] When the prior art has attempted to provide an internal cooling system, the impellers that have been used have not provided sufficient coolant flow to the top of the unit during extended dry-run cycles. Some of the prior art solutions have focused on axial impellers that increase flow, but which have been limited in the head provided with only a single-stage unit.

[005] Another known issue in the prior art is the ability to isolate the working impeller from the coolant impeller when both are located along the same drive shaft.

[006] Another approach has been to circulate the working fluid being pumped around the motor as a coolant. In solid handling pumps, especially as in sewage basin applications, the narrow passages provided around the motor become clogged, resulting in overheating.

[007] A few prior art solutions to these problems are presented in US 5,480,290, where the bent tube extends to the top of the jacket to ensure that coolant liquid will be taken from the top zone of the pump, and US 5,616,973, which has a closed loop system with multiple annular circulation passages.

[008] The problems presented remain unsolved in the prior art known to the inventors.

Summary

[009] These and other unmet objects are met by a pump having a coolant circulation system, and especially a coolant circulation system using a coolant impeller having the features understood by the inventors to present an inventive concept.

[0010] Such a pump for moving a fluid being worked upon comprises a housing, a drive shaft, a motor, a primary impeller, a secondary impeller and a mechanical seal. The housing will generally be of a cylindrical shape, with the drive shaft positioned along an axial length of the housing. The motor is coupled to a first end of the drive shaft in an upper portion of the housing. A cavity is formed inside the housing and extends from the upper portion to a lower portion. The primary impeller is coupled to a second end of the drive shaft in the lower portion of the housing, and is adapted for receiving the fluid being worked upon through an inlet and expelling it through an outlet of the housing.

The secondary impeller is adapted for circulating a coolant in the cavity. The secondary impeller is coupled to the drive shaft above the primary impeller but below the motor. The mechanical seal, positioned along the drive shaft, separates the coolant from the fluid being worked upon.

[0011] In many embodiments, the pump also comprises a motor shroud that contains the motor and the drive shaft in a water tight manner. The motor shroud is arranged inside the housing so that a space in the cavity between the motor shroud and the housing defines a coolant chamber.

[0012] In some embodiments, the cavity will comprise flow channels for directing circulation of the coolant. [0013] In many embodiments, a coolant impeller chamber is provided for the mounting of the secondary impeller, to be rotated by the drive shaft. In these, and other embodiments, a coolant collection basin is also provided, to be in liquid communication with both the coolant chamber and the coolant impeller chamber, which is preferably located above the coolant collection basin.

[0014] An upper shroud of the secondary impeller is provided by a wall of the motor shroud. This upper shroud preferably comprises a conduit that directs coolant, pressurized by the secondary impeller, into the coolant chamber.

[0015] The secondary impeller comprises a set of curved impeller blades and a lower shroud. The lower shroud has an inner portion and a peripheral base disk. These are separated by an annular space that defines a suction eye for the secondary impeller. The peripheral base disk and the inner portion anchor each of the set of curved impeller blades.

[0016] In the embodiments, the drive shaft enters the coolant impeller chamber through a lower portion of the motor shroud and the mechanical seal; an O-ring isolates the coolant impeller chamber from an interior of the motor shroud.

[0017] It is also preferred to provide a bell-shaped element that spaces the coolant collection basin radially outwardly so that the coolant collection basin is under the suction eye of the secondary impeller.

[0018] The mechanical seal contains a seal spring, which, in a compressed condition, acts against the secondary impeller, maintaining a seal.

Brief Description of the Drawings

[0019] A better understanding of the inventive concept will be had when reference is made to the accompanying figures, wherein identical parts are identified by identical part numbers and wherein:

FIG.1 is a side-section elevation view of a pump incorporating the inventive concept;

FIG. 2 is a top partial section perspective view of a coolant circulation system of the Fig. 1 pump; FIG. 3 is a rear partial section perspective view of the coolant circulation system; FIG. 4 is a side section elevation view of the coolant circulation system;

FIG. 5 is a bottom perspective view of the coolant impeller, isolated from the pump; and

FIG. 6 is a top perspective view of the coolant impeller, isolated from the pump.

Detailed Description

[0020] FIGURE 1 shows a side-sectional elevation of pump 10 that includes the inventive concept. Moving from top to bottom, the pump 10 has a bail 12 that is useful in moving the pump into or out of a basin (not shown), a top portion 14 that receives power and control information from an upper portion of the basin, an intermediate portion 16 that contains a motor 18, a drive shaft 20 coupled to the motor, and a cooling system for the motor. Below the intermediate portion 16 is a bottom portion 22 that contains a primary impeller 24, coupled to the drive shaft 20 and surrounded by a chamber 26 in which fluid from a lower portion of the basin is received and pressurized for discharge through an outlet 28, which is adapted for connection to piping that leads out of the basin. Many of the features of the pump 10 described so far are generally known in the art, but the inventive concept lies in the cooling system.

[0021] The bottom portion 22 of pump 10 typically rests upon a floor of the basin, although a plurality of legs 30 may be used to space an axial inlet 32 of the chamber 26 above the basin floor. While not shown in this embodiment, it is known to position a grinder element in or proximate to the axial inlet 32, to reduce the size of solids, particularly stringy solids, that could clog the primary impeller 24. The specific configuration of the primary impeller 24 and the chamber 26 in which it is positioned will largely be design choices that will not affect the inventive concept being disclosed herein, but the preferred primary impeller 24 will be a centrifugal impeller.

[0022] Directing attention more closely to the intermediate portion 16 of pump 10, a housing 40 will preferably be a cylindrical metal tube, adapted at its respective ends for water-tight attachment to the top portion 14 and the bottom portion 22. The motor 18 and drive shaft 20 are contained in a water-tight manner within a motor shroud 42 that is mounted at a top end thereof to the top portion 14 and the housing 40. Motor shroud 42 is generally cylindrical, with a diameter that is smaller than a diameter of the housing 40. This difference in diameters provides for a coolant chamber 44, which may be generally open, but which also may contain defined flow channels for circulation of a coolant liquid. In the preferred manner of operation, the coolant chamber 44 will be substantially filled with the coolant liquid, although a small headspace is desirable at the upper end of the coolant chamber 44 to accommodate expansion/contraction of the coolant liquid during use, as gas in the headspace is able to be compressed. Surfaces of the housing 40 and motor shroud 42 that face into the coolant chamber 44 may be provided with fins or other elements to enhance heat transfer. Further, the outer surface of the housing 40 may similarly be provided with shaped surfaces to enhance heat transfer from the pump 10 into the interior of the basin, keeping in mind that this outer surface may be exposed to air, the liquid in the basin, or a combination of both.

[0023] Continuing with Fig.1 , the coolant system for the pump 10 comprises a coolant circulation system 50, in addition to the coolant chamber 44 and the coolant liquid contained therein. In the illustrated embodiment, this coolant circulation system 50 has a coolant circulation system housing 52 positioned in the intermediate portion 16, directly below the motor shroud 42, to which it is mounted at an upper end thereof. The features of the coolant circulation system 50 include a coolant impeller 54, a coolant impeller chamber 56, and a coolant collection basin 58. The coolant circulation system housing 52 is also mounted to the bottom portion 22. The drive shaft 20 passes from the motor shroud 42 into and through the coolant circulation system housing 52, ending with an end of the drive shaft that extends into the bottom portion 22, where it is coupled to the primary impeller 24. In this manner, the coolant liquid is kept in circulation.

[0024] Also notable as features of the coolant circulation system are at least one passage 60 that communicates the coolant chamber 44 to the coolant collection basin 58, and a conduit 62 at a discharge of the coolant impeller chamber 56 that communicates it to the coolant chamber 44.

[0025] However, the most notable feature of the coolant circulation system is the coolant impeller 54 which solves problems that the inventors do not believe have been successfully addressed in the prior art. The coolant impeller 54 needs to circulate the coolant to cool the motor 18 while operating in a wide range of conditions ranging from fully submerged to continuous dry run. The coolant impeller 54 is designed to obtain enclosed impeller flow characteristics and higher efficiencies and the reliability and ease of use of an open impeller. The coolant impeller 54 uses a wall of the motor shroud 42 located above it as its upper shroud 66. A lower shroud of the coolant impeller 54 is a combination of shroud, suction eye, and a seal spring to provide a mechanical seal. Instead of the traditional suction eye being in the center (as it is in the primary impeller 24), the coolant impeller 54 has a suction eye that is offset into an open annular shape, which allows the inner portion to be acted on by the seal spring of the mechanical seal. A further section of the coolant impeller 54 provides the remaining portion of the shroud for the coolant impeller.

[0026] A known problem in the prior art with impellers for circulating coolant in this sort of application is getting the cooling liquid to the top of the motor shroud unit with enough flow to cool during extended dry-run cycles. Axial impellers can provide more flow but are limited in the amount of head that can be generated with only single stage units.

[0027] FIGURES 2 through 6 depict various views of the coolant impeller 54 that embody the inventive concept. Figures 2 to 4 show the coolant impeller 54 in its operative relationship with the pump and particularly with the coolant circulation system. Figures 5 and 6 show the coolant impeller 54 in isolation so that the individual features may be understood.

[0028] The inventive concept as understood by the inventor has four main features. The first of these is a set of curved impeller blades 70 to provide the push to the coolant to enable it to reach the vertical reaches of the coolant chamber 44. Specifics of the vanes 70, including the vane geometry and number of impeller blades 70 may be varied depending on the amount of flow and head required to cool the pump 10 assembly in which it is installed.

[0029] The second main feature is the suction eye 72 of the coolant impeller 54. Instead of being located in the center of the coolant impeller 54, as would be known in the prior art, the suction eye 72 is offset radially outward. The offset position allows an inner portion 74 to interact with a mechanical seal spring and to pass the drive shaft 20 through the coolant impeller chamber 56. The suction eye 72 depicted in the drawings is a generally open annular space between the inner portion 74 and a peripheral base disk 76. This base disk 76, along with the inner portion 74, anchors the plurality of blades 70, and it is only the axial projection of these blades that keeps the suction eye from being fully open. The suction eye 72 allows coolant liquid to flow through the vanes from the coolant collection chamber 58 below the coolant impeller chamber 56 through the blades 70, where the coolant liquid is propelled through the rest of the assembly.

[0030] The third feature is positioned below the suction eye 72, where the lower shroud is arranged to define the size of the suction eye, provide direction of flow and improve the efficiency of the impeller.

[0031] The fourth feature is the upper shroud 66. Since the upper shroud 66 is provided by a wall of the motor shroud 42, which is directly above it, the upper shroud helps to provide direction of flow and improves the efficiency of the coolant impeller 54. A feature of the upper shroud 66 is the conduit 62 that directs the pressurized coolant liquid from the upper side of the impeller into the conduit 56.

[0032] Directing attention to Figs. 2 and 3, where top and bottom perspective views look into the coolant impeller chamber 56, which is shown in section to view its internals. Drive shaft 20 enters through the lower part of the motor shroud 42 and a mechanical seal 80, and an O-ring 82 isolates the coolant impeller chamber 56 from the interior of the motor shroud 42. Coolant circulation system housing 52 provides a wall to the coolant impeller chamber 56 and coolant liquid can flow outside of it through conduit 60 into coolant collection basin 58.

[0033] Below the impeller 54, a bell-shaped element 84 spaces the coolant collection chamber 58 radially outwardly so that it is primarily under the suction eye of the impeller. The bell-shaped element 84 also isolates the drive shaft 20 from the coolant liquid, positions the impeller 54 along the drive shaft and assists in fixing the coolant circulation system housing system 52 to the bottom portion (not shown in Figs. 2 or 3).

[0034] Looking now at Fig. 4, a side section view of the impeller 54 and its surroundings shows the blades 70, suction eye 72, inner portion 74 and base disk 76. A portion of upper shroud 66 is seen, as is a portion of bell-shaped element 84. A seal spring 86 of the mechanical seal 80, in a compressed condition is able to act on the inner portion 74 of the impeller 54.

[0035] Figures 5 and 6 show perspective views of the coolant impeller 54, isolated from the pump. Readily visible are the blades 70, inner portion 74, base disk 76 and the suction eye 72 provided as an opening between the inner portion and the base disk.

REFERENCE NUMBERS

10 pump

12 bail

14 top portion of pump

16 intermediate portion of pump

18 motor

20 drive shaft

22 bottom portion

24 primary impeller

26 primary impeller chamber

28 outlet of primary impeller chamber

30 legs for pump

32 axial inlet of primary impeller chamber

40 housing of pump

42 motor shroud

44 coolant chamber

50 coolant circulation system

52 coolant circulation system housing

54 coolant impeller

56 coolant impeller chamber

58 coolant collection basin

60 passage connecting coolant chamber to coolant collection basin

62 conduit at discharge of coolant impeller chamber

66 upper shroud of coolant impeller chamber

70 curved impeller blades

72 suction eye of the coolant impeller

74 inner portion of coolant impeller

76 peripheral base disk of coolant impeller

80 mechanical seal O-ring bell-shaped element seal spring of mechanical seal