JP3100543B2 - All circumferential pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-line pump, and more particularly to an all-circular flow type in-line pump in which a suction port and a discharge port are arranged on the axis of a motor shaft.

[0002]

2. Description of the Related Art Conventionally, there has been known an all circumferential flow type in-line pump in which a suction port and a discharge port are arranged on the axis of a motor shaft (for example, European Patent No. EP0009449 and Japanese Patent Application Laid-Open No. 5-332280). This type of pump is required to be small and to have a small dimension between mounting surfaces, for reasons such as piping work. However, the pump disclosed in the above publication does not always satisfy the requirements for downsizing. The most effective means for downsizing the pump is to increase the speed (increase the speed), but the above publication does not have a structure that can completely cope with this method.

[0003] European Patent EP0009449 is a multistage pump in which a plurality of impellers are provided at both ends of a motor shaft. All impellers are provided with sliding parts (liner rings) on both the front side (the side where the suction mouth is located) and the back side, and the balance hole reduces the axial thrust load.

[0004]

However, since the sliding portions are provided on both sides of the impeller, there are the following problems. (1) The overall length of the pump is long, which is not suitable for downsizing. (2) Since the length from the bearing to the shaft end is long, it is disadvantageous in mechanical strength. In particular, the longer the spindle, the lower the critical speed,
Problems are likely to occur when driving at high speeds. That is, the shorter the shaft of the pump used at high speed, the safer it is.

In particular, pumps operated at high speeds are often made of a hard but brittle material such as ceramics for bearings in consideration of durability. At this time, the European patent EP000
If there are sliding portions on both sides of the impeller as in No. 9449, a slight shaft runout or the like will cause the bearing to be broken, so that it takes time to manage dimensional accuracy and the like.

On the other hand, JP-A-5-332280 does not have a mechanism for reducing the thrust load. Therefore, for example, when realizing a high-lift pump by rotating at high speed, the thrust bearing not only increases the sliding speed, but also increases the thrust load (bearing surface pressure), so that durability is left uneasy. .

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a small-sized, all-circumferential pump having high efficiency and good productivity with small dimensions between mounting surfaces.

[0008]

The present invention uses the following means to achieve the above-mentioned object. (1) In the case of a multi-stage pump, impellers are provided at both shaft ends of the motor to reduce the distance from the bearing to the shaft end, and slide on the back surface of one of the front and rear impellers. A portion and a balance hole are provided to reduce the thrust load, and the other back surface has no sliding portion. Since the present invention is configured as described above, it is possible to reduce the axial thrust load while minimizing the overall length (between surfaces) of the pump. In addition, the distance from the bearing to the shaft end is short and mechanically stable. Further, the number of sliding portions and balance holes can be reduced, and the pump efficiency is good. Since there are few sliding parts, it is easy to develop a ceramic bearing, and it is possible to reduce the size by increasing the speed.

(2) Also in the case of a multi-stage pump, the inner casings accommodating the impellers at both shaft ends of the motor are connected to each other by bolts. If you do not use through bolts,
For example, the inner casing needs to be fixed to the motor frame side plate. At this time, it is necessary to make the side plate thicker in the axial direction because a bolt seat is provided on the motor frame side plate. This increases the cost of the side plate itself. Further, when the bolt seat is provided on the outer peripheral portion of the side plate, it is difficult to perform a welding operation with the outer frame of the motor frame, resulting in poor productivity.

(3) The suction portion of the impeller is directed toward the motor,
The inner casing that accommodates the impeller and forms the sliding portion with the back of the impeller is shaped to cover the shaft end of the motor.
In European Patent No. EP0009449, the main shaft penetrates the corresponding portion to form a sliding portion. The clearance cannot be made very small in the sliding portion due to mechanical circumstances. Therefore,
A large amount of leakage leads to lower efficiency. The present invention, on the other hand, does not have a sliding portion and has only a small hole for venting air, so that the amount of leakage can be minimized. Also,
By making the shape of the inner casing into a dome shape, the handled liquid discharged from the impeller can be efficiently guided to the pump discharge port, and at the same time, air can be reliably vented by the air vent hole provided at the top of the dome.

(4) The mounting position of the frequency converter is devised to minimize unnecessary space, and the size of the apparatus is reduced by increasing the speed of the pump. In other words, when high-speed operation is performed in an all-circulation flow type inline pump, the most effective method is to attach a frequency converter represented by an inverter to the outer surface of an outer cylinder and cool the inverter with a liquid to be handled.
This is because no fan or the like for cooling the inverter is required, and the entire device is compact. (5) In the case of a single-stage pump, an impeller is provided on the discharge port side, and an inducer is provided on the suction port side. Particularly, in the case of a pump driven at a high speed, there is a case where an inducer is provided in order to secure suction performance. At this time, if the impeller and the inducer are provided at the same shaft end of the motor, the shaft end becomes longer, and the above-described problem occurs. This is similar to the case where two stages of impellers are provided at the same shaft end. The inducer is housed in the suction nozzle without providing any special space. Therefore, the suction performance can be ensured without increasing the size of the pump for the inducer.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a pump assembly according to the present invention will be described below with reference to FIGS. FIG. 1 is a cross-sectional view showing an all-peripheral flow type inline pump according to the present invention, and FIG. 2 is a cross-sectional view taken along line II-II of FIG.

The all circumferential flow type motor pump shown in this embodiment is
It comprises a pump casing 1, a canned motor 6 housed in the pump casing 1, and impellers 8 and 9 fixed to both ends of a main shaft 7 of the canned motor 6. The pump casing 1 includes a pump casing outer cylinder 2 and flanges 6 at both ends of the pump casing outer cylinder 2.
Suction casings 3 connected by
And a discharge casing 4. Pump casing outer cylinder 2, suction casing 3, and discharge casing 4
Is formed by a sheet metal made of stainless steel or the like.

Upper and lower cases 47, 48 accommodating an inverter (frequency converter) 46 are fixed to the outer surface of the outer cylinder 2. A gasket 49 is interposed between the upper and lower cases 47 and 48.

The first-stage impeller 8 in the suction casing 3 is accommodated in a first inner casing 10 having a guide device 10a. An elastic seal 12 is interposed between the first inner casing 10 and the suction casing 3.
A liner ring 45 is provided at an inner end of the first inner casing 10.

On the other hand, the canned motor 6 is
A motor frame outer shell 14 provided on an outer peripheral portion of the stator 13, motor frame side plates 15 and 16 welded and fixed to both open ends of the motor frame outer shell 14, and an inner peripheral portion of the stator 13. The motor frame side plate 15,
16 and a can 17 fixed by welding. The rotor 18 rotatably accommodated in the stator 13 is shrink-fitted and fixed to the main shaft 7. An annular space (flow path) 40 is formed between the motor frame outer shell 14 and the outer cylinder 2.

The motor frame side plate 16 of the canned motor 6 holds a guide member 11 for guiding the fluid from the outside in the radial direction to the inside. And the guide member 11
Has a second inner casing 12 for accommodating the second-stage impeller 9.
Has been fixed. The first inner casing 10 and the guide member 11 are connected to each other by a through bolt 41 that passes through the annular space (flow path) 40. Since the second inner casing 12 is fixed to the guide member 11, the first
The inner casing 10 and the second inner casing 12 are connected to each other.

A liner ring 5 is provided on the inner end of the guide member 11.
0 is provided, and the liner ring 50 slides on the front surface (the suction mouth side) of the second stage impeller 9. A liner ring 51 is also provided on the inner end of the second inner casing 12, and the liner ring 51 slides with a wear ring 52 provided on the back surface of the second stage impeller 9. . The second inner casing 12 has a substantially dome shape, and has a shape covering the shaft end of the main shaft 7 of the canned motor pump 6. The second inner casing 12 has a guide device 12a formed of a guide vane or volute for guiding the fluid discharged from the second stage impeller 9. The second inner casing 12 has an air vent hole 12b at the tip.

A lead wire housing 20 is fixed to the motor frame outer shell 14 by welding, and a lead wire is drawn out from a coil in the motor frame outer shell 14 to the outside via the lead wire housing 20, and the lower case 48 It is connected to the inverter 46 in the upper and lower cases 47, 48 via the lead wire outlet hole 48a. The lead wires of the inverter 46 are connected to the power cable 63 in the upper and lower cases 47 and 48. The outer cylinder 2 is formed with a hole 2a, and the lead wire housing 20 is inserted into the hole 2a.

Next, the peripheral portion of the bearing on the second stage impeller 9 side will be described. The bearing bracket 21 is provided with a radial bearing 22 and a fixed-side thrust bearing 23. The end face of the radial bearing 22 is also provided with a function as a fixed-side thrust sliding member. On both sides of the radial bearing 22 and the fixed-side thrust bearing 23, a rotating-side thrust bearing 24 and a rotating-side thrust bearing 25, which are rotating-side thrust sliding members, are provided. Rotating thrust bearing 24
Is fixed to a thrust disk 26, which is fixed to the main shaft 7 via a key. The rotation-side thrust bearing 25 is fixed to a thrust disk 27, and this thrust disk 27 is
It is fixed to.

The bearing bracket 21 is inserted into a spigot provided on the motor frame side plate 16 via an O-ring 29 made of an elastic material. Bearing bracket 2
1 is in contact with the motor frame side plate 16 via a gasket 30 made of an elastic material. In the drawing, reference numeral 31 denotes a sleeve forming a sliding portion with the radial bearing 22.

Next, the peripheral portion of the bearing on the side of the first stage impeller 8 will be described. The bearing bracket 32 is provided with a radial bearing 33. In the figure, reference numeral 34 denotes a sleeve which forms a sliding portion with the radial bearing 33. The sleeve 34 comes into contact with a washer 35, and this washer 35 is
Are fixed by screws and nuts 36 provided at the ends of the. The bearing bracket 32 is inserted into a spigot provided on the motor frame side plate 15 via an O-ring 37 made of an elastic material. The bearing bracket 32 is in contact with the motor frame side plate 15.

A stay 43 is welded to the outer frame 14 of the motor frame, and the stay 43 and the outer cylinder 2 are fixed by welding. The rotation speed of the canned motor 6 is set to 4000 rpm or more by the inverter 46.

The operation of the all circumferential pump shown in FIG. 1 will be briefly described. The fluid sucked from the suction nozzle 3a connected to the suction casing 3 passes through the first inner casing 10 and the first stage impeller. 8 is led. The fluid discharged from the first stage impeller 8 is formed between the outer cylinder 2 and the motor frame outer shell 14 of the canned motor 6 after the flow direction is changed from the centrifugal direction to the axial direction via the guide device 10a. It flows into the annular flow path 40, is guided by the guide member 11 through the flow path 40, and is guided into the second stage impeller 9. The liquid discharged from the second stage impeller 9 is discharged from the discharge nozzle 4a connected to the discharge casing 4 via the guide device 12a.

According to the present invention, the impellers 8 and 9 are provided at both shaft ends of the canned motor 6 so as to reduce the distance from the bearing to the shaft end. A thrust load is reduced by providing a sliding portion consisting of a balance hole 9a, and no sliding portion is provided on the back surface of the impeller 8 in the preceding stage. This makes it possible to reduce the axial thrust load while minimizing the overall length (between surfaces) of the pump. In addition, the distance from the bearing to the shaft end is short and mechanically stable. Further, the number of sliding portions and balance holes can be reduced, and the pump efficiency is good. Since there are few sliding parts, it is easy to develop into a ceramic bearing, and it is possible to reduce the size by increasing the speed.

Further, by providing the liner ring 51 on the back surface of the impeller 9 at the subsequent stage, a tensile stress can be applied to the main shaft. In general, a rotating shaft is mechanically more stable in a state subjected to a tensile stress than in a state subjected to a compressive stress.

According to the present invention, the sliding diameter of the liner ring 51 provided on the back of the impeller 9 is larger than the sliding diameter of the liner ring 50 provided on the front of the impeller 9. Thus, for example, the axial thrust load for two stages of the impeller can be offset.

Further, according to the present invention, the inner casing 1 for accommodating the impellers 8 and 9 at both shaft ends of the canned motor 6 respectively.
0 and 12 are connected to each other by bolts 41. When the through bolt is not used, it is necessary to fix the inner casing to, for example, a motor frame side plate. At this time, it is necessary to make the side plate thicker in the axial direction because a bolt seat is provided on the motor frame side plate. This increases the cost of the side plate itself. Further, when the bolt seat is provided on the outer peripheral portion of the side plate, it is difficult to perform welding work with the outer frame of the motor frame, and the productivity is poor.

According to the present invention, the suction portion of the impeller 9 is directed toward the motor, and the second inner casing 12 that accommodates the impeller 9 and forms a sliding portion with the back surface of the impeller is connected to the main shaft of the canned motor 6. The end of 7 is covered. In European Patent No. EP0009449, the main shaft penetrates the corresponding portion to form a sliding portion. The clearance cannot be made very small in the sliding portion due to mechanical circumstances. Therefore, a large amount of leakage leads to a decrease in efficiency. The present invention, on the other hand, does not have a sliding portion and has only a small hole 12b for venting air, so that the amount of leakage can be minimized. Further, by making the shape of the second inner casing 12 into a dome shape, the handled liquid discharged from the impeller 9 is efficiently guided to the pump discharge port, and at the same time, the air vent hole 12b provided at the top of the dome surely ensures. Air can be removed.

According to the present invention, the suction performance can be improved by making the suction mouth diameter of the front impeller 8 larger than the suction mouth diameter of the rear impeller 9.
Generally, a pump operated at a high speed requires a device to ensure suction performance. One of the means for improving the suction performance is to increase the diameter of the suction mouth of the impeller, but it is also known that if the diameter is too large, the pump efficiency is reduced. Further, in the case of a multi-stage pump, it is known that securing the suction performance of the first-stage impeller leads to improvement in the suction performance of the entire pump. Therefore, by configuring as in the present invention, it is possible to realize a small-sized high-speed pump having relatively good pump efficiency and ensuring suction performance.

In the present invention, the impeller 9 at the subsequent stage is used.
Is larger than the outer diameter of the impeller 8 at the preceding stage.
The impeller 8 (pump section) in the former stage needs to convert the handling liquid discharged from the impeller from the centrifugal direction to the axial direction, so that the outer diameter of the impeller cannot be increased. On the other hand, the impeller 9 on the rear stage only needs to return the flow in the centrifugal direction to the axial center side, so that the outer diameter of the impeller can be increased. As a result, the pump can generate a high head without increasing the internal space, so that the pump is relatively small.

In the present invention, since the canned motor 6 is used as the motor, a shaft sealing device such as a mechanical seal is not required, and the axial dimension can be minimized. Also, because self-lubricated bearings are used,
There is no need to fill the rotor chamber with the lubricating liquid. Therefore, an oil seal or the like for that purpose is not required, and the axial dimension can be minimized from this surface.

In the present invention, the radial bearing 2
2, 33 and the thrust bearings 23, 24 are ceramic bearings. In the embodiment, silicon carbide (SiC) is used for these bearings. SiC is excellent in durability and can withstand practical use without any problem even if the handling liquid contains some slurry. However, since SiC has a hard but brittle property, if the shaft end is long or the number of sliding parts is large as shown in European Patent No. EP0009449, the bearing may be broken due to slight shaft runout. . In this sense, the structure of the present invention employs and matches the SiC bearing.

Further, according to the present invention, there is provided a terminal portion comprising a lead wire housing 20 or the like configured to take out the lead wire of the motor stator 13 to the outer surface of the outer cylinder 2, and attached to the terminal portion from the outside of the outer cylinder 2. Is a full-circulation pump having a frequency converter 46 provided and a pump suction port and a pump discharge port provided on the axis of the motor shaft. The terminal portion has two coil ends e, e of a motor stator winding. And the impeller 9 is mounted by extending the shaft end on the terminal side among the shaft ends of the motor. When high-speed operation is performed in the all circumferential flow type in-line pump, the most effective method is to mount a frequency converter 46 typified by an inverter on the outer surface of the outer cylinder 2 and cool the inverter with a handled liquid. This is because no fan or the like for cooling the inverter is required, and the entire device is compact.

In the case of forming an inline pump in which the suction port and the discharge port of the pump are provided on the axis of the motor shaft, there is a problem in which shaft end of the motor shaft the impeller is mounted. In this case, if an impeller is provided at the shaft end opposite to the terminal portion, an extremely useless space is created in the discharge casing. This is a waste of convenience for installing the inverter,
As a result, the face-to-face dimension of the pump is increased, which does not meet the purpose of “smaller pump by increasing speed”. In the present invention, by adopting the above-described configuration, the inverter can be effectively attached to the pump body without causing waste, and the entire apparatus is made compact and compact.

FIG. 3 is a sectional view showing a second embodiment of the all circumferential pump of the present invention. 3, components having the same functions and functions as the components of FIG. The all circumferential flow type pump of the present embodiment is a single-stage in-line type pump. That is, the impeller 9 is provided only on the shaft end of the canned motor 6 on the discharge casing 4 side, and the impeller is not provided on the shaft end on the suction casing 3 side. Therefore, no inner casing is provided in the suction casing 3. Since no through bolt is provided in the annular flow passage 40, the inner casing 12 is fixed to the guide member 11 by a bolt. Other configurations are the same as those of the embodiment shown in FIG.

The operation of the all circumferential flow type inline pump shown in FIG. 3 will be briefly described. Fluid sucked from the suction nozzle 3a passes through the suction casing 3 and the outer cylinder 2 and the motor frame outer cylinder 14 of the canned motor 6. Flows into the annular flow path 40 formed between the first and second members, and is guided by the guide member 11 through the flow path 40 to be guided into the impeller 9. The fluid discharged from the impeller 9 is discharged from the discharge nozzle 4a connected to the discharge casing 4 via the guide device 12a.

In this embodiment, since only a single-stage impeller is provided, the effect obtained by the multi-stage impeller is not exhibited, but the liner rings 50 and 51 centering on the impeller 9 are provided.
1 is the same as that of the embodiment of FIG. 1, so that the basic effects obtained in the embodiment of FIG. 1, such as reduction of the axial dimension and improvement of the pump efficiency, are the same.

FIG. 4 is a sectional view showing a third embodiment of the all circumferential flow type pump according to the present invention. 4, components having the same functions and functions as the components of FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. The all circumferential flow type pump of this embodiment is one in which an inducer is provided in the single-stage in-line type pump shown in FIG. That is, the impeller 9 is provided only on the shaft end of the canned motor 6 on the discharge casing 4 side, and the impeller is not provided on the shaft end on the suction casing 3 side, but an inducer 55 is provided instead. I have. The inducer 55 includes a boss 55a fixed to the main shaft 7, a plurality of blades 55b, and a collar 55c.
To the main shaft 7. Note that reference numeral 57 is
This is an inducer casing that accommodates the inducer 55. Other configurations are the same as those of the embodiment shown in FIG.

The operation of the all circumferential flow type in-line pump shown in FIG. 4 will be briefly described. The fluid sucked from the suction nozzle 3a passes through the inducer 55,
Through the outer cylinder 2 and the annular flow path 40 formed between the motor frame outer shell 14 of the canned motor 6, and is guided by the guide member 11 through the flow path 40, so that the impeller 9
Guided inside. The fluid discharged from the impeller 9 is discharged from the discharge nozzle 4a connected to the discharge casing 4 via the guide device 12a.

According to this embodiment, the impeller 9 is provided on the discharge port side, and the inducer 55 is provided on the suction port side. Particularly, in the case of a pump driven at a high speed, there is a case where an inducer is provided in order to secure suction performance. At this time, if the impeller and the inducer are provided at the same shaft end of the motor, the shaft end becomes longer, and the above-described problem occurs.
This is similar to the case where two stages of impellers are provided at the same shaft end.

In this embodiment, the inducer 55 is accommodated in the suction nozzle 3a without newly providing a special space. Therefore, the suction performance can be ensured without increasing the size of the pump for the inducer. The treated liquid passing through the inducer 55 is given a flow velocity in the axial direction by the inducer 55. In order to guide this axial fluid flow smoothly in the centrifugal direction, the inducer 55 is provided with a collar 55c. The inducer 55 is fixed by a female screw provided on itself and a male screw provided on the main shaft 7, and a double nut is formed and fixed by providing a shaft end nut 56 at the shaft end of the main shaft 7. Thus, it is possible to prevent the inducer from falling off at the time of reverse rotation or the like and to minimize the length of the shaft end.

The inducer 55 (similar to a general one) is set so as to have a relatively low head and a large amount of water compared to the impeller. Thereby, the suction performance is improved, and for example, the problem of cavitation that is likely to occur when used at high speed can be solved. Inducer 5
Since 5 is provided at the shaft end opposite to the impeller 9, the shaft end length (overhang from the bearing) does not substantially extend.
Further, since the inducer 55 is provided in the suction nozzle 3a, there is no need to increase the inter-plane dimension of the inline pump. That is, by providing the inducer 55,
The outer dimensions of the pump do not increase. Rather, the improved suction performance allows the pump to rotate at higher speeds, making the device extremely compact.

[0044]

As described above, according to the present invention, the overall length of the pump can be shortened, and the pump efficiency can be improved by reducing the number of sliding portions and balance holes. According to the present invention, the suction performance can be improved by providing the inducer. Since the inducer is accommodated in the suction nozzle, the pump is not increased in size for the inducer.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a first embodiment of an all circumferential flow type pump according to the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a sectional view showing a second embodiment of the all-periodic flow pump according to the present invention.

FIG. 4 is a sectional view showing a third embodiment of the all-periodic flow pump according to the present invention.

[Explanation of symbols]

 Reference Signs List 1 pump casing 2 outer cylinder 3 suction casing 4 discharge casing 6 canned motor 7 main shaft 8, 9 impeller 13 stator 14 motor frame outer body 15, 16 motor frame side plate 17 can 18 rotor 21, 32 bearing bracket 22, 33 radial Bearing 23 Fixed thrust bearing 24 Rotating thrust bearing 43 Stay 46 Inverter 47 Upper case 48 Lower case 49 Gasket 50, 51 Liner ring 52 Wear ring 55 Inducer

──────────────────────────────────────────────────続 き Continued on the front page (72) Koji Isemoto, Inventor 4-2-1 Motofujisawa, Fujisawa City, Kanagawa Prefecture Inside Ebara Research Institute Co., Ltd. (72) Kaoru Yagi 4-2-2, Motofujisawa, Fujisawa City, Kanagawa Prefecture 1 Ebara Research Institute Co., Ltd. (72) Keita Uei 4-2-1 Motofujisawa, Fujisawa-shi, Kanagawa Prefecture 1-2. Ebara Research Institute Co., Ltd. (72) Yoshiaki Miyazaki 4-2-2 Motofujisawa, Fujisawa-shi, Kanagawa Prefecture No. 1 Inside EBARA Research Institute Co., Ltd. (72) Katsuji Iijima 4-2-1 Motofujisawa, Fujisawa City, Kanagawa Prefecture Inside EBARA Research Institute Co., Ltd. (72) Inventor Junya Kawabata 11 Asahimachi Haneda, Ota-ku, Tokyo No. 1 EBARA CORPORATION (56) References JP-A-7-243392 (JP, A) JP-A-5-332280 (JP, A) JP-A-6-88586 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) F04D 13/06

Claims (17)

(57) [Claims] An outer cylinder forming an annular space between an outer peripheral surface of a motor frame provided on an outer peripheral portion of a stator of the motor; an outer cylinder forming an annular space between the outer peripheral surface of the outer peripheral body of the motor frame; A front-stage impeller that guides the handling liquid to the space, and a full-circulation flow type pump that includes a second-stage impeller provided at the other end of the motor shaft and that takes in the handling liquid from the annular space; A full-circulation pump comprising a liner ring provided on the back of one of the impellers and no liner ring provided on the back of the other impeller. 2. The all-peripheral flow pump according to claim 1, wherein a liner ring is provided on a rear surface of the rear stage impeller. 3. The entire circumference according to claim 1, wherein a sliding diameter of a liner ring provided on a rear surface of the impeller is larger than a sliding diameter of a liner ring provided on a front surface of the impeller. Flow type pump. 4. The wear ring according to claim 3, wherein a wear ring made of a separate member is fixed to a ring-shaped projection provided on the back surface of the impeller, and a sliding diameter with the fixed side liner ring is increased. All circumferential pump. 5. The all-circumferential flow type according to claim 1, wherein a suction mouth diameter of said front stage impeller is larger than a suction mouth diameter of said rear stage impeller. pump. 6. An outer diameter of said rear stage impeller is larger than an outer diameter of said front stage impeller.
The all-circumferential pump according to any one of claims 1 to 5. 7. The all circumferential flow type pump according to claim 1, wherein the motor is a canned motor. 8. The bearing for supporting the motor shaft is a sliding bearing made of ceramic.
The all circumferential flow type pump according to any one of the above. 9. The method according to claim 1, wherein the number of rotations of the motor is 4000 rpm or more.
All-circumferential pump according to the above item. 10. The all circumferential flow type pump according to claim 1, wherein a suction port and a discharge port of the pump are provided on the axis of the motor shaft to constitute an in-line type pump. pump. 11. A motor frame outer body provided on an outer peripheral portion of a stator of a motor, an outer cylinder forming an annular space between the outer peripheral surface of the motor frame outer body, and a pump for introducing a handling liquid to the annular space. An impeller and an inner casing for accommodating the impeller are provided at both shaft ends of the motor, and the inner casings are connected to each other by a through bolt passing through the annular space. All circumferential flow type pump. 12. A motor frame outer body provided on an outer peripheral portion of a stator of a motor, an outer cylinder forming an annular space between the outer peripheral surface of the motor frame outer body, and a pump for guiding a liquid to be handled to the annular space. In the all-circumferential pump with the part, the suction mouth side of the impeller faces the motor side, the front casing and the rear face of the impeller are provided with liner rings, and the inner casing for fixing the liner ring on the rear face of the impeller is provided. An all-circumferential pump characterized in that the shaft end of the motor is covered. 13. A motor frame outer body provided on an outer peripheral portion of a stator of a motor, an outer cylinder forming an annular space between the outer peripheral surface of the motor frame outer body, and a pump for guiding a handling liquid to the annular space. An all-circle flow pump having a portion, wherein an impeller is provided at one end of a motor shaft, and an inducer is provided at the other end of the motor shaft to improve suction performance of the impeller. Flow type pump. 14. The pump according to claim 13 , wherein a suction nozzle is provided so as to cover an outer periphery of the inducer. 15.-type full-circumferential-flow pump according to claim 13 or 14, characterized in that a collar for guiding the pumped fluid that has passed through the inducer smoothly into the annular space. 16.-type full-circumferential-flow pump according to any one of claims 13 to 15, wherein the inducer is screwed to the main shaft. 17. The all circumferential flow type pump according to claim 16 , wherein a shaft end nut is provided on an upstream side of the inducer.