US 3637329 A
A canned motor pump has a stator sealed from a rotor, the rotor driving a shaft that carries an impeller. The shaft rotates in front and rear bearings while the thrust of the impeller is balanced by fluid passing through an orifice plate behind the impeller. A front bearing housing is separate from but interconnected with the orifice plate by an adapter. The stator may be externally heat exchange jacketed, while a guide disc may be carried by the front bearing housing to direct fluid radially inwardly toward the intake of an auxiliary impeller.
Claims available in
Description (OCR text may contain errors)
United States Patent Sato et al. 51 Jan. 25, 1972 PUMP  References Cited  inventors: Ryuichi Sato; Seizi Harimaya; Akihiko UNITED STATES PATENTS Agata; Kunio Morishima; Toshiaki lsutsui; Y K k l McConaghy.... a Japan 2,687,695 8/1954 Blom et al ..4I7/368 x  Assignee: Nikkiso Co., Ltd., Tokyo, Japan Primary Examiner-Robert M. Walker  Ffled' June 1970 Attorney-Young & Thompson  Appl. No.: 42,250
ABSTRACT  Foreign Application Priority Data A canned motor pump has a stator sealed from a rotor. the rotor driving a shaft that carries an impeller. The shaft rotates May 29, 1969 Japan ..44/41940 in from and rear bearings while he thrust of he impeller is balanced by fluid passing through an orifice plate behind the impeller. A front bearing housing is separate from but inter. z i 424 370 4 connected with the orifice plate by an adapter. The stator may be externally heat exchange jacketed, while a guide disc may be carried by the front bearing housing to direct fluid radially inwardly toward the intake of an auxiliary impeller.
3 Claims, 5 Drawing Figures PATENTEnJmzsmz s.637 .329 $MH1UF3 I FIG.I (PRIOR ART) I 36 6 l8 59 l l 29 2 8 26 25 38 I4 4 I00 34 42 33 a r 32 M 1 (11 lg w] KUNIO MORISHIMAJOSHIAKI TSUTSUI YASUHIRO- KANO BY *JW ATTORNEYS PATENTEDmzsmz 3537.329 sum 20F 3 l I20 H8 H6 I28 'INVENTOR RYUICHI SATO SEIZI HARIMAYA AKIHIKO AGATA I KUNIO MORISHIMA, TOSHIAKI TSUTSUI YASUHIRO KANO ATTORNEY3 PATENTED JAHZS 1972 z H2 INVENTOR RYUICHI SATO, SEIZI HARIMAYA, AKIHIKO AGATA,
KUNIO MORISHIMA, TOSHIAKI TSUTSUI, YASUHIRO KANO BY QJW ATTORNEYS PUMP The present invention relates to canned motor pumps of the type driven by an electric motor having the stator and rotor sealed from each other by a sheet of nonmagnetic metal such as stainless steel. A portion of the liquid from the pump delivery is returned to the rotor chamber and passes between the rotor and the stator and through the front bearing of the rotor shaft and thence through balancing orifices to the rear of the impeller mounted on the shaft.
Known pumps of this type mount the front shaft bearing in a bearing housing which also provides a rear wall for the impeller chamber, the balancing orifices passing through this same member. However, this construction has been found to be disadvantageous, because various motor assemblies may require variations in this member disposed between the impeller chamber and the motor chambers. Also, on the other hand, variations in the impeller and its operating characteristics may require variations in the arrangement of the balancing orifices; so that again, it is necessary to provide a number of different types of members separating the impeller and motor chambers, for use under various conditions having to do with the impeller. It frequently happens, for example, that the dimensions dqS, D4: and I must be varied, as indicated in FIG. I of the accompanying drawings.
Accordingly, it is an object of the present invention to provide a canned motor pump, in which difi'erent requirements with respect to the front shaft bearing and/or the impeller chamber may be quickly and easily satisfied with a minimum of different parts.
Another object of the present invention is the provision of such a pump, which will be relatively simple and inexpensive to manufacture, easy to install, adjust, maintain, operate and repair, and rugged and durable in use.
Briefly, the present invention achieves these objects by providing a front bearing housing which is separate from an orifice plate behind the impeller, and by interconnecting these two members by means of an adapter.
Optionally, the stator can be heat exchange jacketed. Also optionally, an auxiliary impeller can be carried by the rotor shaft for circulation of the pumped liquid through the rotor chamber, with the front bearing housing carrying a guide disc that deflects liquid to the central intake portion of the auxiliary impeller.
Other objects, features and advantages of the present invention will become apparent from a consideration of the following description, taken in connection with the accompanying drawings, in which:
FIG. 1 is a view in longitudinal cross section of a pump of the general type of the present invention, but constructed according to the prior art;
FIG. 2 is an enlarged fragmentary view, from the side opposite the side shown in FIG. I, of a pump according to the present invention in the vicinity of the front shaft bearing and impeller thereof;
FIG. 3 is a view similar to FIG. 2, but showing another embodiment of pump according to the present invention, for use in high-temperature applications;
FIG. 4 is a fragmentary cross-sectional view of one embodiment of heat exchange jacket disposed about the stator of the motor shown in FIGS. 2 and 3; and
FIG. 5 is a view similar to FIG. 4 but showing another embodiment of heat exchange jacket.
Referring now to the drawings in greater detail, and first by way of background to the prior art construction shown in FIG. I, there is shown a canned motor pump of known type in which a stator I0 surrounds a rotor 12 with a sheet of nonmagnetic metal such as stainless steel sealing the rotor chamber from the stator chamber. A portion of the pumped liquid is removed from the pump outlet 16 through a conduit 18 and recirculated to a chamber 20 rearwardly of the rotor, the liquid then passing through a flow channel in the rear bearing 22, through the clearance 24 between rotor 12 and stator 10, through the front bearing 25, through orifices 26 that extend along the shaft, and thence to the rear of the impeller 28 where the liquid passes through symmetrically arranged openings 30 to be pumped again by the impeller.
The front bearing 25 is carried by a front bearing housing 32 that has a radially outwardly extending portion 33 that forms a rear wall for the impeller chamber. The orifices 26 pass through the radially inner portion of housing 32.
The pump casing is shown at 34, a closureplate at 36, and a stator housing at 38. The rotor shaft is designated 40, while the rear bearing housing is shown at 42. The pump assembly is indicated generally at 44, the stator assembly generally at 46, and the rotor assembly generally at 48.
Turning now to FIG. 2, a first embodiment of the present invention is shown. Briefly stated, the member 32 of FIG. I has been replaced by three members comprising a separate front bearing housing for the shaft, a separate orifice plate for directing fluid to the rear side of the impeller, and an adapter to interconnect the front bearing housing and the orifice plate. The front bearing housing can be changed according to the varying motor and shaft requirements, mentioned above. The orifice plate can be selected according to the varying pump requirements, mentioned above.
With more particular reference to FIG. 2, there is shown an adapter 50 in the form of an annular member having one end face 52 that abuts end closure plate 54 of the stator housing and whose forward end face 56 in turn lies flat against end face 52 of adapter 50. The forward end face 58 of adapter 50 abuts the pump assembly in a manner to be explained. The motor assembly and pump assembly and adapter 50 are interconnected by conventional detachable fastening means (not shown).
FIG. 3 differs from FIG. 2 in that the structure of FIG. 3 is especially adapted for high temperature operation. The structure shown in FIG. 3 includes an auxiliary impeller 60 secured to the rotor shaft 40 and disposed in an auxiliary pump chamber 62 formed between the adapter 50' and the front bearing housing 64. Auxiliary impeller 60 thus circulates liquid from the auxiliary chamber 62 through a delivery connection 66 and thence through a circulation conduit 68 to the rear of the rotor chamber, in the manner indicated in FIG. 1, thereby to provide a recirculation system that is independent of the main impeller circulation.
As is also shown in FIG. 3, an annular guide disc 70 is secured to the forward peripheral surface 74 of edge portion 72 of front bearing housing 64. Recirculating liquid passes through the orifices 76 through housing 64, moving to the right as seen in FIG. 3, and is deflected by guide disc 70 to the radially inner portion of auxiliary impeller 60, which is the intake portion or suction side of impeller 60, thereby to improve the circulation of the liquid.
The novel combination of the present invention also includes an orifice disc 78 (FIG. 2) or 78' (FIG. 3) having a rear face which abuts the adapter 50 or 50, while a forward end face 82 coacts with the impeller to balance the axial thrust of the impeller. It should be particularly noted that this orifice disc is separate from the front bearing housing and is spaced therefrom by the adapter.
Although an outer periphery 84 of the orifice disc is shown in engagement with an inner periphery of an end portion 88 of the pump casing 86, the orifice disc may be secured to the adapter 50 only, or the end face 80 of the disc 78 may be of an enlarged size and may be engaged with an end face 92 of the pump casing 86.
An end face 94 of the front bearing housing 64 is joined with a recessed end 96 of the front end closure plate 54 and clamped by suitable conventional detachable fastening means (not shown). Alternatively, the edge portion 72 of the bearing housing may be extended so that the end face 94 may be faced with the whole end face area of the end closure plate 54.
The end closure plate 54 forms with a stator housing member 98 and the sheet 14 and a rear end closure plate 100 (FIG. 1) a chamber for the stator assembly. This front end closure plate 54 is secured to thebearing housing 64 and the adapter 50 or 50', or alternatively only with the housing 64 in of housing member 98, which makes for ease of assembling and disassembling the parts.
The liquid circulating in the rotor housing not only lubricates the bearings but also absorbs the heat of the motor. To cool this liquid, a jacket assembly or jacket-type heat exchange assembly is disposed about the outer periphery of the stator housing, as seen in FIGS. 4 and 5. In the FIG. 4 em bodiment, a jacket assembly 104 is comprised of a jacket body 106, a cover plate 108, a gasket 110, a plug 112, and an inlet 114 for fluid heat exchange medium. in the FIG. 5 embodiment, the jacket-type heat exchange assembly 116 is comprised of a jacket body 118, a cover plate 120, a gasket 122, a plug 124, an inlet 126, and circulation tubing 128 for a portion of the heat exchange fluid, The inner diameters of jacket bodies 106 and 118 are preferably the same as the outer diameter of the stator housing member 98 so that the heat exchange jackets can be easily mounted on the stator housing.
From a consideration of the foregoing disclosure, therefore, it will be evident that all of the initially recited objects of the present invention have been achieved.
Although the present invention has been described and illustrated in connection with preferred embodiments, it is to be understood that modifications and variations may be resorted to without departing from the spirit of the invention, as those skilled in this art will readily understand. Such modifications and variations are considered to be within the purview and scope of the present invention as defined by the appended claims.
Having described our invention, we claim:
1. A canned motor pump comprising a pump casing having an inlet and an outlet, an impeller disposed in the pump casing and mounted on a shaft, an electric motor comprising a stator,
a rotor within the stator and mounted on said shaft, a plurality of bearings for said shaft spaced along said shaft, one of said bearings being nearest said impeller, a bearing housing in which said one bearing is mounted, an orifice disc disposed behind the impeller and having orifices therethrough for conveying fluid to the rear of the impeller to balance the thrust of the impeller, and an adapter disposed between and removably secured to said bearing housing and said orifice disc whereby said bearing housing and adapter and orifice disc are removably secured to each other.
2. A pump as claimed in claim 1, and an auxiliary impeller on the shaft adjacent said bearing housing, said bearing housing having openings therethrough for the transmission of fluid toward said auxiliary impeller, and an annular guide disc on said bearing housing between said bearing housing and said auxiliary impeller for deflecting fluid passing through said openings in a direction radially inwardly of said auxiliary impeller, and means to transmit fluid from said auxiliary impeller to the rear of said shaft.
3. A canned motor pump as claimed in claim 1, and a heat exchange jacket surrounding said stator, and means to supply a fluid to the interior of said heat exchange jacket.