JP3090818B2 - Multi-stage canned motor pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multistage canned motor pump, and more particularly to a multistage canned motor pump having a balance disk disposed between a motor section and a pump section. Part of the gas flows into the rear rotor chamber from the front rotor chamber via the pressure chamber that houses the balance disk, and after lubricating through the rear bearing part, returns to the pump suction port through the through shaft hole at the rear end of the motor rotor shaft. An internal circulation (circulation) system for lubricating the bearings and cooling the motor section is provided, and the balance chamber formed by providing an annular seal in the low pressure side rear chamber of the balance disk communicates with the through shaft hole of the motor rotor shaft. The present invention relates to a multistage canned motor pump that improves a thrust holding force by forming a communication hole for connection.

[0002]

2. Description of the Related Art Generally, a balance disk of a conventional multi-stage pump is, as apparent from a half sectional view of a multi-stage pump 10 shown in FIG. 4A and a partially enlarged view shown in FIG.
The rear chamber 14 side of the balance disk 12 is connected to a pump suction port side 18 by an external circulation (circulation) system 16 so as to be maintained at a low pressure.

In general, a multi-stage canned motor pump employs circulation for cooling the motor section and lubricating the bearings, and it is preferable to form the same flow as the flow for the balance disk in order to reverse the flow. It is simpler in structure and more effective in design than it is formed.

However, the applicant has paid attention to the characteristics of the balance disk and has filed an application for a multi-stage canned motor pump as described below. That is, in order to reduce the pressure in the motor chamber 20 as much as possible like the multistage canned motor pump 15 shown in FIG. 5, the rear part 22 of the motor chamber and the suction port 26 side of the pump chamber 24 are connected by a sufficiently thick external pipe 28, The pressure loss in the external pipe 28 is configured to be sufficiently small.

[0005] Originally, the canned motor pump is characterized by no leakage, and a system in which a circulation pipe is provided outside is not preferable because the number of sealing points increases accordingly and the possibility of leakage increases. For this reason, a through hole 34 is provided in the motor rotor shaft 32 of the single-stage canned motor pump 30 as shown in FIG. 6, so that an internal circulation system in which a part of the handled liquid is returned to the suction port side of the pump is mainly used. ing.

[0006]

Therefore, if such a system is to be adopted for a canned motor pump using a balance disk, in a multi-stage canned motor pump, the motor rotor shaft integrally includes the pump shaft and the motor shaft. As a result, the overall length becomes longer, and the diameter of the shaft through-hole is limited due to the relationship of the shaft strength, so the pressure loss in the through-hole increases and the pressure in the balance disk rear chamber increases, The balance holding force was reduced, and there was a problem that the internal circulation system could not be adopted as it was.

However, the internal circulation system has the advantage that it can be manufactured at low cost because there are few leaks and the number of attached pipes is small. Further, the thrust balance mechanism using the balance disk is stable in the entire flow region. Internal circulation system that adopts a balance disk system because it can achieve balance and eliminate balance holes and annular seals on the rear side, and can reduce leakage loss and disc friction loss and improve pump efficiency It was desired to adopt.

Accordingly, an object of the present invention is to adopt a balance disk mechanism in a multi-stage canned motor pump, and to communicate with a through hole of a motor rotor shaft to a balance chamber formed by providing an annular seal in a low pressure side rear chamber of the balance disk. By forming a communication hole and holding the balance chamber at a low pressure, a stable thrust holding force is achieved, thereby improving the efficiency of the pump, and by using an internal circulation system, the reliability is improved. It is to provide a low-cost multistage canned motor pump.

[0009]

In order to achieve the above object, the present invention provides a motor unit disposed coaxially behind a pump unit comprising a plurality of pump chambers, and a motor unit and a pump unit. In a multi-stage canned motor pump having a balance disk disposed therebetween, a part of the handling liquid sucked from the pump suction port and discharged from the final stage pump chamber is stored in the balance disk disposed adjacent to the rear of the final stage pump chamber. After flowing into the rear rotor chamber from the front rotor chamber through the pressure chamber, and further flowing through the rear bearing part, the lubricating oil flows back to the pump suction port through the through shaft hole at the rear end of the motor rotor shaft, and lubrication of the bearing and motor part An internal circulation system for cooling the pressure chamber is formed, and the pressure chamber is divided into a front chamber and a rear chamber by a balance disk, and the outer side edges of the balance disk are sealed in the pressure chamber. An annular balance sheet is disposed to,
An annular projection is provided on the rear chamber side surface of the balance disc to form a balance chamber that seals the inner peripheral edge of the rear chamber balance sheet, and the pressure chamber has a gap outside the balance sheet and a front motor chamber. And a communication hole that connects the balance chamber and the through-shaft hole of the motor rotor shaft to each other is formed in the shaft attachment portion of the balance disk.

In this case, a communication hole communicating with the through shaft hole is provided on at least one pump chamber suction port side closer to the pump suction port than the communication hole of the balance chamber communicating with the through shaft hole of the motor rotor shaft. It is preferable to provide them.

[0011]

According to the present invention, a pressure chamber for accommodating a part of the handling liquid discharged from the last stage pump chamber of a multistage canned motor pump having a balance disk disposed between the motor section and the pump section is provided. After flowing into the rear rotor chamber from the front rotor chamber through the rear bearing part, and then flowing through the rear bearing part, it returns to the pump suction port from the through shaft hole at the rear end of the motor rotor shaft to lubricate the bearing and cool the motor part. By forming an internal circulation (circulation) system so as to perform, and forming a communication hole communicating with a through shaft hole of the motor rotor shaft in a balance chamber formed by providing an annular seal in the low pressure side rear chamber of the balance disk. The thrust holding force can be improved.

[0012]

Next, an embodiment of a multistage canned motor pump according to the present invention will be described in detail with reference to the accompanying drawings. For convenience of description, the same components as those of the conventional structure shown in FIGS. 4 to 6 are denoted by the same reference numerals, and detailed description will be omitted.

FIG. 1A is a half sectional view of a multi-stage canned motor pump according to the present invention, and FIG. 1B is a pressure gradient diagram.

In the drawing, reference numeral 36 denotes a multi-stage canned motor pump main body, and an internal circulation (circulation) system employed in the multi-stage canned motor pump 36 is sucked from the pump suction port 26 and the final stage pump chamber 38 is provided.
A part of the handling liquid discharged from the
2 flows into the rear rotor chamber 46 from the front rotor chamber 44 shown in FIG.
After the lubricating oil flows, the motor is returned to the pump suction port 26 side from the through shaft hole 52 at the rear end of the motor rotor shaft 50 to lubricate the rear bearing 48 and the intermediate bearing 54 and cool the motor portion 56. I have.

A pressure chamber 42 for accommodating the balance disk 40 is defined by a balance disk 40 into a front chamber 42a and a rear chamber 42b as shown in FIG. A pair of annular balance sheets 45a and 45b for sealing both side edges are provided.

Further, an annular projection 49 is projected from the side surface of the balance disk 40 on the rear chamber 42b side to seal an inner peripheral edge of the balance sheet 45b on the rear chamber 42b side.
The pressure chamber 42 is formed as a balance chamber, and the pressure chamber 42 is formed with a liquid passage 54 communicating the gap 47 outside the balance sheets 45a and 45b and the front rotor chamber 44. A radial communication hole 58 that connects the chamber 42b and the through shaft hole 52 of the motor rotor shaft 50 is formed.

Here, the multistage canned motor pump will be described with reference to FIG. 1 (b) in relation to a pressure gradient diagram in each part of the multistage canned motor pump.
First, in the figure, the solid line part is a pressure gradient diagram of the internal circulation of the multi-stage canned motor pump.
₁ the pressure in the pump inlet 26, the pressure of P ₂ is the final stage pump chamber, P ₃ is the pressure in the pressure chambers 42, the P ₄ is the pressure of the motor section rear, P _'B is the rear chamber of the pressure chambers 42 (Balance chamber) Pressure on the 42b side.

Further, one-dot chain line portion represents a pressure gradient diagram in the case of an external circulation system of the multistage canned motor pump, in the diagram, P _'3 is the pressure in the pressure chambers 42 P' ₄ is the motor section Indicates the pressure on the rear side.

More specifically, in FIG. 1B, after the suction pressure P ₁ in the multi-stage pump of the present invention is increased to P ₂ (pressure gradient diagram a ') in the final stage (for example, the sixth stage), When the pressurized handling liquid flows into the pressure chamber 42, the pressure before and after the balance disk 40 becomes P ₃
And a pressure difference of P ₂ −P ₃ = P _{h ′} is generated.

A part of the handling liquid that has flowed into the room is a balance disc 40 and balance sheets 45a and 45b.
Of the balance chamber 42b
, The flow to the motor side can be sufficiently ensured while maintaining a low pressure.

Further, the pressure P ₃ is further reduced to P ₄ (pressure gradient diagram e) on the rear side of the motor portion, and flows through the through hole 52 of the motor rotor shaft 50 to the pump suction port 26 side. It is refluxed and the pressure drops to P ₁ (diagram f).

In this case, the balance chamber 42 of the pressure chamber 42
b communicates with the through shaft hole 52,
The pressure of the inner is 'for stepping down to _B, the highest pressure P ₂ significant pressure differential P H' P can be obtained.

On the other hand, in the case of the external circulation system shown by the dashed line, the liquid pressure P ₂ in the final stage is reduced to P ′ _{3 in the} pressure chamber 42, and further reduced to P ′ ₄ on the rear side of the motor unit. Therefore, no problem occurs because the pressure difference P _'4 -P ₁ is reduced when it is refluxed until the suction port 26 by an external circulation.

That is, conventionally, when there is no annular seal for sealing the chambers before and after the balance disk in the pressure chamber for storing the balance disk and the communication hole 58 for communicating the rear chamber with the motor rotor, the pressure P _{3 in the} pressure chamber is not balanced. The thrust holding force T ₁ generated in the balance disk 40 becomes equal to the pressure P _{B in the} rear chamber 42 b of the disk 40, and T ₁ = T ₁ = A _{1 where} the pressure receiving area of the balance disk 40 is A ₁ , and the pressure of the final stage pump chamber is P _2. From A ₁ · (P ₂ -P ₃ ), = A ₁ · P _{h '} .

On the other hand, in the present invention, the handling liquid reduced to the pressure P ₃ in the balance chamber 42b on the rear side of the balance disk 40 provided in the pressure chamber 42 flows through the motor section 56, some vacuum pressure P ₄ next flow into, to be configured to return to the communicating hole 58 communicating with the balance chamber 42b which is formed substantially in the middle of the motor rotor shaft 50, the pressure here is P _'B The pressure is greatly reduced until.

Therefore, in this case, the balance disk 40
, The thrust holding force T ₂ is changed from T ₂ = A ₁ · (P ₂ −P ′ _B ) to = A ₁ · P _{H '} , and a sufficient thrust holding force can be generated. Here, the case of the external circulation is no longer a problem since the pressure difference is small in the (P _'4 -P _1).

Next, FIG. 3 shows an example in which, in the internal circulation, the handled liquid refluxed to the suction port through the communication hole 58 communicating from the shaft hole of the motor rotor shaft to the balance chamber 42b is returned to the middle of the multistage pump chamber. Will be described.

In FIGS. 3A and 3B, the same structures as those described above are denoted by the same reference numerals, and detailed description thereof will be omitted.

That is, in the present embodiment, as shown in FIG. 3A, the through shaft hole 52 of the motor rotor shaft 50 is closer to the suction port 26 than the communication position with the communication hole 58 communicating with the balance chamber 42b. Intermediate part of multistage pump chamber (for example, 3rd stage and 4th stage)
(Stage) It is configured to communicate with the pump chamber.

That is, in the pressure gradient diagram of FIG. 3B, the first through third holes communicating with the communication holes 58 provided in the through shaft holes 52 are formed.
The pressure P ₁ · P _R up to the stage is indicated by a diagram a whose head is
The heads of the pressures P _R and P ₂ up to the sixth stage are indicated by b.
The pressure P _{2 at the} final stage is the pressure difference between the maximum pressure P ₂ in the front chamber 42 a and the rear chamber 42 b in the front chamber 42 a or the rear chamber 42 b of the balance disk 40 in the pressure chamber 42.
In the differential pressure between the maximum pressure P ₂ is shown diagrammatically d.

Furthermore, the pressure at the rear side of the motor section 56 the differential pressure between P ₃ steps down to P ₄ is the diagram e is obtained, the pressure difference between P ₄ · P _R inside circulation is diagram Indicated by f.

In FIG. 3 (b), as shown by the dotted line, the pressure P is considered even if the change g of the vapor pressure of the liquid handled in the pump section 56 and the pressure increase h accompanying the rise in the liquid temperature due to the cooling of the motor section are taken into consideration.
_{For R} , a safety margin up to the occurrence of cavitation can be taken.

Therefore, with this configuration, the pressure of the motor section can be increased as shown in FIG. 3B, and the cavitation of the motor section can be reduced even when a special liquid having a high vapor pressure is handled. Suppression becomes possible.

Although the present invention has been described with reference to a preferred embodiment, the present invention is not limited to the above-described embodiment.
Many modifications can be made without departing from the spirit thereof.

[0035]

As described above, in the multistage canned motor pump according to the present invention, a part of the handled liquid sucked from the pump suction port and discharged from the last stage pump chamber is arranged adjacent to the rear of the last stage pump chamber. After flowing into the rear rotor chamber from the front rotor chamber through the pressure chamber for storing the balance disk, and after further lubricating the rear bearing part,
An internal circulation system is configured to return to the pump suction port from the through shaft hole at the rear end of the motor rotor shaft to perform lubrication of the bearing and cooling of the motor part. An annular balance sheet that seals both outer edges of the balance disk is disposed in the pressure chamber, and an annular protrusion is provided on a rear chamber side surface of the balance disk to form an inner peripheral edge of the rear chamber balance sheet. To form a balance chamber, form a liquid passage communicating the gap between the pressure chamber outside the balance sheet and the front motor chamber, and provide the balance chamber and the motor rotor shaft at the shaft mounting portion of the balance disk. By forming a communication hole that connects and communicates with the through shaft hole, a stable balance mechanism can be realized and achieved, and an efficient pump can be achieved and the thrust holding force can be improved. Improve reliability by employing a circulation and has excellent effects such as can be made inexpensive in cost.

[Brief description of the drawings]

FIG. 1A is a half sectional view of a multi-stage canned motor pump showing one embodiment of a multi-stage canned motor pump according to the present invention, and FIG. 1B is a pressure diagram at each point of the multi-stage canned motor pump. It is.

FIG. 2 is an enlarged sectional view of a balance mechanism of the multi-stage canned motor pump.

FIG. 3 (a) is a half sectional view of a multi-stage canned motor pump showing another embodiment of the multi-stage canned motor pump according to the present invention, and FIG. 3 (b) is a pressure line at each point of the multi-stage canned motor pump. FIG.

4A is a half sectional view of a conventional multistage canned motor pump employing an external circulation system, and FIG. 4B is an enlarged sectional view of a balance mechanism employed in the conventional multistage canned motor pump. is there.

FIG. 5 is a half sectional view of a conventional multistage canned motor pump employing an external circulation system.

FIG. 6 is a half sectional view of a conventional single-stage canned motor pump employing an internal circulation system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Multistage canned motor pump 12 Balance disk 14 Rear room 15 Multistage canned motor pump 16 External circulation system 18 Pump suction port 20 Motor room 22 Rear of motor room 24 Pump room 26 Pump suction opening 28 External piping 30 Single stage canned motor pump 32 Motor rotor Shaft 34 Through-hole 36 Multistage canned motor pump 38 Final stage pump chamber 40 Balance disk 42 Pressure chamber 42a Front chamber 42b Rear chamber 44 Front rotor chamber 45a, 45b Balance sheet 46 Rear rotor chamber 47 Gap 48 Rear bearing 50 Motor rotor shaft 52 Through shaft hole 54 Intermediate bearing 55 Shaft attachment part 56 Motor part 58 Communication hole

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-224495 (JP, A) JP-A-52-55001 (JP, A) JP-A-52-2204 (JP, U) JP-A-49 14501 (JP, U) Japanese Utility Model Showa 54-142804 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F04D 13/02 F04D 1/06 F04D 15/00 102

Claims (2)

(57) [Claims] 1. A multi-stage canned motor pump in which a motor section is disposed coaxially behind a pump section comprising a plurality of pump chambers and a balance disk is disposed between the motor section and the pump section. A part of the handled liquid which is sucked in and discharged from the last-stage pump chamber flows from the front rotor chamber to the rear rotor chamber via the pressure chamber that stores the balance disk disposed adjacent to the rear of the last-stage pump chamber, Further, after the lubricating flow through the rear bearing portion, an internal circulation system is formed to return to the pump suction port from the through shaft hole at the rear end of the motor rotor shaft to lubricate the bearing and cool the motor portion. An annular balance sheet for defining the front and rear chambers by the disc and sealing the outer side edges of the balance disc in the pressure chamber is provided. An annular projection protrudes from the rear chamber side surface to form a balance chamber that seals the inner peripheral edge of the rear chamber balance sheet, and the pressure chamber communicates with the gap outside the balance sheet and the front motor chamber. A multi-stage canned motor pump, wherein a communication passage is formed in the shaft attachment portion of the balance disk to connect the balance chamber and a through shaft hole of the motor rotor shaft. 2. A communication hole communicating with the through shaft hole is provided on at least one pump chamber suction port side closer to the pump suction port than a communication hole of the balance chamber communicating with the through shaft hole of the motor rotor shaft. The multi-stage canned motor pump according to claim 1, comprising: