JPS6364639B2 - - Google Patents

Description

[Detailed description of the invention] [Technical field to which the invention pertains] The present invention relates to a canned motor pump, and particularly to a method for pump handling fluid introduced into the canned motor in order to lubricate bearings inside the canned motor and cool the motor section. This invention relates to flow rate control means.

[Prior art and its problems]

Generally, in a canned motor pump, a part of the pump liquid is taken out from the discharge side of the pump part and guided into the canned motor, and the liquid is pumped between the bearing surface of the bearing that supports the rotor shaft and between the stator and rotor. After flowing through the pump system, the liquid is circulated to the pump system. In this case, by keeping the amount of lubricant and coolant flowing through the lubricating surface of the bearing and the cooling surface of the motor at necessary and appropriate values, the amount of unnecessary leakage relative to the pump discharge amount can be reduced. can increase the overall efficiency of

From this point of view, in conventional canned motor pumps, in order to maintain the required amount of lubricating fluid and cooling fluid to the canned motor section, for example, there are Spiral grooves and axial grooves are carved.

However, in conventional canned motor pumps, the grooves formed on the inner circumferential surfaces of the front and rear bearings have the same shape, and therefore the flow path resistance is also the same. For this reason, the pressure difference between the front and rear of the bearing becomes large, especially in the bearing on the side where pump handling liquid is introduced.
This bearing part had the disadvantage of causing an excessive flow (leakage) of liquid beyond what was necessary, reducing the overall efficiency of the pump below its design efficiency. In particular, after introducing a part of the pump handling liquid into the canned motor from the joint between the pump part and the canned motor part, lubricating the front bearing and cooling the motor part by flowing between the stator and rotor. In a reverse circulation type canned motor pump, which lubricates the rear bearing and circulates liquid to the suction side of the pump, the pressure difference described above occurs in the front bearing, causing excess liquid. It was found that a significant amount of flow through the pump occurred and the overall efficiency of the pump was significantly reduced.

[Purpose of the invention]

An object of the present invention is to maintain the amount of lubricating fluid at the minimum necessary level by changing the flow path resistance to the lubricating surfaces of the front bearing and rear bearing, which are placed under different pressure conditions in a canned motor. An object of the present invention is to provide a canned motor pump that can reduce the amount of leakage in a pump part and easily improve the overall efficiency of the pump.

[Key points of the invention]

In order to achieve the above object, in the present invention, a pump part and a canned motor part are connected, a part of the pump handling liquid is introduced into the canned motor part from this joint part, and a part of this pump handling liquid is transferred to the front part. The can is configured to lubricate the bearing and circulate it to the low pressure side of the pump section, while the pump handling liquid in the canned motor section passes through the gap between the stator and rotor to lubricate the rear bearing and then circulates to the suction side of the pump section. The motor pump is characterized in that the flow path resistance to the lubricated surface of the front bearing is set to be greater than the flow path resistance to the lubricated surface of the rear bearing.

That is, in the present invention, the pump part and the canned motor part are connected by an adapter, and a part of the pump handling liquid is introduced into the canned motor part from this joint part, and the front bearing is lubricated, and this lubricating liquid is transferred to the pump part. In a canned motor pump, the lubrication of the front bearing is circulated to the suction side of the pump section, and after passing through the gap between the stator and rotor, the rear bearing is lubricated, and the flow is then returned to the suction side of the pump section. By setting a large flow path resistance to the rear bearing surface and a small flow path resistance to the lubricating surface of the rear bearing, the amount of lubricating fluid can be minimized to meet the pressure conditions of the pump handling fluid that occur on each bearing. can be held for a limited time.

In the above-mentioned canned motor pump, no groove is provided on the inner peripheral surface of the front bearing, but a spiral groove or a straight groove is carved on the inner peripheral surface of the rear bearing that is oriented in the direction that facilitates the flow of liquid when the rotor shaft rotates. It is suitable if As an alternative, it is also preferable to carve a spiral groove on the inner circumferential surface of the front bearing that is oriented in a direction that makes it difficult for the liquid to flow when the rotor shaft rotates.

In addition, the pump part and the canned motor part are connected by an adapter, and a through hole is bored in the rear wall of the pump part to introduce the pump handling liquid, and the pump handling liquid that has lubricated the front bearing is transferred to the low pressure side of the pump part. It is preferable to provide a shaft through-hole for circulation.

Furthermore, the pump handling fluid guided to the rear of the canned motor section, including the fluid that lubricated the rear bearings, is configured to be circulated to the suction side of the pump system via an external circulation tube or through a hole in the rotor shaft. It is preferable to configure it so that it circulates to the low pressure side of the pump section through the provided central hole.

[Embodiments of the invention]

Next, embodiments of the canned motor pump according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a sectional view showing an embodiment of a canned motor pump according to the present invention. The basic configuration of the canned motor pump shown in FIG. 1 is the same as that of the conventional canned motor pump. That is,
In FIG. 1, reference numeral 10 is a pump section, 12
indicates a canned motor section, and the pump section 10 and motor section 12 are connected by an adapter 14.

The pump section 10 includes a suction pipe section 20 and a discharge pipe section 2 that communicate with a pump chamber 18 in which an impeller 16 is provided.
2, and the impeller 16 is attached to the extended end of the rotor shaft 24 of the motor section 12. On the other hand, the motor section 12 includes a stator assembly 26 and a rotor assembly 28. The rotor shaft 24 is supported by a front bearing 30 and a rear bearing 32, respectively. A rotor chamber 36 is formed. The front rotor chamber 34 and the rear rotor chamber 36 are supported by bearing housings 38 and 40, respectively, and each bearing housing 38 and 40 is provided with a liquid passage hole 42 and 44, and the front bearing 30 and the rear bearing 32 are supported by bearing housings 38 and 40, respectively. The structure is such that smooth lubrication by the handling liquid is achieved.

Further, the pump chamber 18 and the front rotor chamber 34 are partitioned by a partition wall 46, and a through hole 48 is bored on the outer circumferential side of the partition wall 46. Therefore, in this case, a portion of the handled liquid in the pump chamber 18 flows through the liquid passage 50 defined by the adapter 14 that connects the pump section 10 and the canned motor section 12 via the passage hole 48.
and then drilled into the bearing housing 38 holding the front bearing 30 to form a fluid passage hole 42.
is guided into the front rotor chamber 34 through. In this way, a part of the pump handling fluid that has flowed into the front rotor chamber 34 lubricates the inner circumferential portion of the front bearing 30, and a portion of the pump handling liquid flows into the front rotor chamber 34, lubricating the inner circumferential portion of the front bearing 30. Then, it flows out to the low pressure part of the pump chamber 18 through a balance hole 54 formed in the impeller 16. Further, the pump handling liquid that has flowed into the front rotor chamber 34 cools the motor section through the gap between the stator 26 and the rotor 28, and then flows into the rear rotor chamber 34.
will be guided to. The pump handling liquid that has flowed into the rear rotor chamber 36 lubricates the inner circumferential surface of the rear bearing 32 and flows into the bearing housing 40 through a liquid passage hole 44 formed in the bearing housing 40.
into the compartment 56 formed by. Therefore, the pump handling liquid flowing into this compartment 56 is appropriately circulated to the suction side of the pump system via an external circulation tube 58. Alternatively, the pump handling liquid that has flowed into the compartment 56 may be
The rotor shaft 24 can be configured to be guided through a central hole 60 formed in the rotor shaft 24 to the shaft through hole 52 of the compartment 46 provided in the pump section 10 and circulated to the low pressure section of the pump chamber 18 .

However, in the present invention, in order to appropriately control the flow rate of the pump handling liquid guided to the inner circumferential surfaces of the front bearing 30 and rear bearing 32, for example, grooves are formed on the inner circumferential surface of the front bearing 30. On the other hand, on the inner peripheral surface of the rear bearing 32, a spiral groove 62 is carved in a direction that facilitates the flow of liquid when the rotor shaft 24 rotates, or a straight groove 64 in the axial direction is formed. (indicated by a broken line) to set the flow path resistance small.

With this configuration, for the front bearing 30, the shaft through hole 52 of the partition wall 46 that communicates with the front rotor chamber 34 and the low pressure part of the pump chamber 18 is provided.
However, in this case, the inner peripheral surface of the front bearing 30, which is the lubricating surface, has a large flow resistance.
It is possible to keep the amount of lubricating fluid to the necessary minimum. On the other hand, the liquid guided to the rear bearing 32 decreases while passing through the gap between the stator 26 and the rotor 28, but the inner circumferential surface of the rear bearing 32, which serves as a lubricating surface, is set to have low flow resistance. As a result, the amount of lubricant applied to the rear bearing 32 can be kept to the minimum necessary level, similarly to the front bearing 30. As a result, the circulation flow rate of the pump handling liquid to the motor section 12, which is considered to be leaking from the pump section 10, is reduced as a whole, and the overall efficiency of the canned motor pump can be increased.

The flow rate characteristics of the canned motor section of the canned motor pump of this embodiment described above were tested in comparison with a canned motor pump of the same configuration with the front and rear bearings having the same structure as before, as shown in Figure 2. characteristics were obtained. That is, the characteristic lines A〓, A〓, shown in Fig. 2
The contents of B〓 and B〓 are as follows.

A〓: Amount of liquid flowing into the rear rotor chamber of the conventional pump A〓: Amount of liquid flowing into the rear rotor chamber of the pump of the present invention B〓: Total circulating fluid volume of the conventional pump B〓: Total circulating fluid of the pump of the present invention Quantity As is clear from FIG. 2, according to the pump of the present invention, the amount of lubricating fluid supplied to the rear bearing 32 can be maintained at almost the same amount as the conventional pump, and the total amount of circulating fluid can be halved. It was confirmed that the following can be maintained.

〔Effect of the invention〕

As is clear from the embodiments described above, according to the present invention, in a canned motor pump configured such that a part of the pump handling liquid is introduced from the front bearing side and circulated to the suction side of the pump via the rear bearing, By increasing the flow path resistance to the lubricated surface of the front bearing and decreasing the flow path resistance to the lubricated surface of the rear bearing, the amount of lubricant is maintained at an appropriate level according to the pressure difference of the pump handling liquid that acts on each bearing. The amount of leakage to the pump section can be reduced, and the overall efficiency of the pump can be easily improved.

In addition, in the above-described embodiment, as a means for increasing the flow path resistance with respect to the front bearing,
Although the case in which no grooves are provided is shown, as an alternative, it is also suitable to provide spiral grooves in a direction that makes it difficult for the liquid to flow when the rotor shaft rotates.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the canned motor pump structure of the above-described embodiments; It goes without saying that not only can the present invention be applied to all of the above, but also that various other design changes can be made without departing from the spirit of the present invention.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a main part of an embodiment of a canned motor pump according to the present invention, and FIG. 2 is a comparative characteristic diagram of the amount of circulating fluid between the pump of the present invention and a conventional pump. 10... Pump section, 12... Canned motor section, 14... Adapter, 16... Impeller, 18
... pump chamber, 20 ... suction pipe section, 22 ... discharge pipe section, 24 ... rotor shaft, 26 ... stator assembly, 28 ... rotor assembly, 30 ... front bearing, 32 ... rear bearing, 34... Front rotor chamber, 36... Rear rotor chamber, 38... Bearing housing, 40... Bearing housing,
42, 44...Liquid hole, 46...Painting wall, 48...
Through hole, 50...Liquid passage, 52...Shaft through hole, 54
... Balance hole, 56 ... Drawing chamber, 58 ... Circulation tube, 60 ... Center hole, 62 ...
...Spiral groove, 64...Straight groove.

Claims (1)

[Scope of Claims] 1. A pump part and a canned motor part are connected, a part of the pump handling liquid is introduced into the canned motor part from this joint part, and a part of this pump handling liquid is used to lubricate the front bearing and then the pump part is connected to the canned motor part. In a canned motor pump, the liquid is circulated to the low-pressure side of the pump section, while the pump handling liquid in the canned motor section passes through the gap between the stator and rotor, lubricates the rear bearing, and then circulates to the suction side of the pump section. A canned motor pump characterized in that flow path resistance to the lubricated surface of the rear bearing is set to be greater than flow path resistance to the lubricated surface of the rear bearing. 2. In the canned motor pump according to claim 1, the inner circumferential surface of the front bearing is not provided with a groove, and the inner circumferential surface of the rear bearing is provided with grooves oriented in a direction that facilitates the flow of liquid when the rotor shaft rotates. Canned motor pump with spiral grooves or straight grooves. 3. The canned motor pump according to claim 1, wherein a helical groove is formed on the inner circumferential surface of the front bearing in a direction that makes it difficult for liquid to flow when the rotor shaft rotates. 4. In the canned motor pump according to any one of claims 1 to 3, the pump part and the canned motor part are connected by an adapter, and the pump handling liquid is introduced into the rear partition wall of the pump part. A canned motor pump that has a through hole and a shaft through hole that circulates the pump handling fluid that lubricates the front bearing to the low pressure side of the pump section. 5. In the canned motor pump according to any one of claims 1 to 4, the pump handling fluid guided to the rear of the canned motor section, including the fluid that lubricates the rear bearing, is supplied to the canned motor pump by external circulation. A canned motor pump configured to circulate to the suction side of the pump system via a tube. 6. In the canned motor pump according to any one of claims 1 to 4, the pump handling liquid guided to the rear of the canned motor part, including the liquid that lubricates the rear bearing, is provided through a hole in the rotor shaft. A canned motor pump configured to circulate to the low pressure side of the pump section through a central hole.