JPH0736150Y2 - Canned motor pump - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a canned motor pump, and particularly when a liquid that easily vaporizes is introduced into the canned motor part, it smoothly flows in the canned motor part without being vaporized. The present invention relates to an improvement for preventing cavitation in the canned motor unit configured as described above.

[Conventional technology]

Generally, in canned motor pumps that handle easily vaporized liquids or high-temperature liquids, part of the pumped liquid introduced into the canned motor part or the liquid introduced from the outside will come out of the motor part when passing through the rotor chamber. Often, the heat is absorbed or decompressed to generate cavitation, which damages the erosion of the bearing surface of the bearing and the rotor and the stator, and often vaporizes rapidly when leaving the canned motor section. Therefore, for example, when a part of the pump handling liquid or another liquid that is easily vaporized is introduced into the rotor chamber of the canned motor from the outside, the liquid guided to the rotor chamber is easily vaporized and cavitation easily occurs. A means for transferring the vaporized liquid by connecting the rear rotor chamber to the vapor zone of the liquid supply tank through a pipe without circulating this liquid to the discharge side of the main pump (this is generally a reverse circulation system) However, in this case, there is a problem in that a long piping facility is required from the pump installation position to the liquid supply tank, which makes the piping work troublesome and increases the facility cost.

The applicant of the present invention has already disclosed that in a canned motor pump of this type, one side of the discharge pipe of the main pump and the rear rotor chamber of the motor unit are communicated with each other through a circulation tube to connect the front rotor chamber and the main pump chamber. An auxiliary pump chamber is provided between the auxiliary pump chamber and the discharge pipe of the main pump to communicate with each other through another circulation tube, and a part of the liquid handled by the pump is connected to the rear rotor chamber, the rear bearing, the rotor / stator, and the front. We proposed a pump configured to pass through the bearings and the front rotor chamber sequentially and to be returned to the discharge pipe of the main pump by the action of the auxiliary pump.
A patent was obtained as Japanese Patent No. 782368 (Japanese Patent Publication No. 49-37922).

That is, according to the pump of the above-mentioned invention, the circulation tubes are arranged in the discharge pipes of the pumps respectively, and the pump handling liquid is circulated into the circulation system by the boosting action of the auxiliary impeller, so that the motor section is cooled and lubricated. Further, by cooling the heat-generating portion of the motor unit, the circulating liquid whose temperature has risen recirculates to a portion (discharge port) having a high pressure, which makes it difficult to vaporize and effectively prevents the circulating liquid from being gasified.

However, in the above-mentioned pump, since there is a slight pressure drop in the circulation tube during actual pump operation, the front bearing on the suction side of the auxiliary pump is placed in an environment with a relatively low pressure level and exposed to dry air. It is easy to be done.

Therefore, as a result of further research and improvement, the applicant efficiently extracted a part of the pump handling liquid from the discharge side of the pump part to the auxiliary pump chamber, boosted it to an appropriate pressure with an auxiliary impeller, and increased this pressure. Flowing the generated liquid into the canned motor in a fixed direction without any special flow path design ensures smooth circulation of the pumped liquid and proper lubrication of the front and rear bearings, and also ensures the occurrence of cavitation. We have succeeded in developing a canned motor pump that can be prevented, and proposed it as, for example, Japanese Patent Publication No. 62-13516.

[Problems to be solved by the device]

However, in the improved canned motor pump described above, when the suction pressure of the pump decreases, the pressures of the auxiliary impeller inlet and the rotor chamber also decrease. Therefore, when operating in this state, the auxiliary impeller cannot pressurize the circulating fluid in the rotor chamber, and rather tends to cause cavitation. As a result, problems such as generation of erosion in the cans and bearings, a decrease in the flow rate of the circulating fluid in the rotor chamber, and a decrease in the ability to cool the motor unit occur.

Therefore, an object of the present invention is to provide an auxiliary pump on the pump side adjacent to the front bearing in the front rotor chamber of the canned motor unit, and to provide a liquid equivalent to the pump handling liquid (pump handling liquid) from the outside in the rear rotor chamber. Not only the same kind of liquid as
Even if it is of a different type, it mixes with the pump handling liquid and contains a liquid that does not interfere with the pump) and introduces this liquid to the pump side with the operation of the auxiliary impeller of the auxiliary pump to lubricate the bearings and In a canned motor pump configured to perform cooling, the structure of the auxiliary impeller has been improved to reduce the suction pressure of the main pump so as to maintain sufficient flow resistance so that the pressure level on the canned motor side does not drop. Even so, it is an object of the present invention to provide a canned motor pump that can effectively prevent the occurrence of cavitation by maintaining a high pressure in the rotor chamber.

[Means for Solving the Problems]

In the canned motor pump according to the present invention, an auxiliary pump is provided in the front rotor chamber of the canned motor unit adjacent to the front bearing on the pump unit side, and a liquid equivalent to the pump handling liquid is introduced from the outside into the rear rotor chamber. The vaporization of this liquid is carried out along with the operation of the auxiliary impeller of the auxiliary pump to the pump portion side through the outer peripheral portion of the motor rotor and the front rotor chamber to lubricate the bearing and cool the motor portion. In a canned motor pump that handles easy-to-use liquid or high-temperature liquid, a closed type blade with a suction port opened on the pump side is used as the auxiliary impeller, and the required backflow to the front rotor chamber side is achieved by the action of this auxiliary pump. A throttle mechanism is provided in a part of a gap of a shaft penetrating portion of a rotor shaft that connects the auxiliary pump and the pump chamber. It is characterized in that a required flow path resistance is maintained so that the pressure level on the rotor chamber side does not decrease.

[Action]

According to the canned motor pump according to the present invention, the front rotor chamber is provided with an auxiliary pump adjacent to the front bearing on the pump chamber side, and a liquid equivalent to the pump handling liquid is introduced into the rear rotor chamber from the outside. In a canned motor pump configured to guide the liquid to the pump part side together with the operation of the auxiliary impeller of the auxiliary pump to lubricate the bearing and cool the motor part, when handling a liquid that easily vaporizes as a pump handling liquid, By the action of the auxiliary impeller, which is a blade with a suction port open to the front side, a required backflow is generated to the front bearing side, increasing the flow resistance in the front rotor chamber, and the suction pressure of the pump part is increased. Even if the pressure drops, the pressure in the rotor chamber of the canned motor portion can be kept sufficiently high, and the occurrence of cavitation can be effectively prevented.

〔Example〕

An embodiment of a canned motor pump according to the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 shows an embodiment of a canned motor pump according to the present invention. That is, in FIG. 1, reference numeral 10 indicates a pump portion, 12 indicates a canned motor portion, and the pump portion 10 and the canned motor portion 12 are connected via an adapter 14. The front rotor chamber 16 and the rear rotor chamber 18 of the canned motor unit 12 are provided with front bearings 24 and rear bearings 26 supported by bearing housings 20 and 22, respectively, and rotors extending to both ends of a motor rotor 28. Support the shaft 30. Further, an auxiliary impeller 32 is axially attached to the rotor shaft 30 at a portion of the front rotor chamber 16 that is connected to the adapter 14 to form an auxiliary pump. The canned motor pump configured as described above has an appropriate throttle mechanism in a part of the shaft penetrating portion gap 34 through which the rotor shaft 30 of the adapter 14 penetrates.
36 is provided, and a circulating fluid supply system 38 communicating with the rear rotor chamber 18 is connected to the rear portion of the canned motor portion 12.

The canned motor pump according to the present embodiment configured as described above is configured to generate a liquid from the circulating liquid supply system 34 into the rear rotor chamber 18 at a required pressure, which is the same as the pump handling liquid or which does not cause any trouble even when mixed with the pump handling liquid. Introduce. In this way, the circulating fluid introduced into the rear rotor chamber 18 of the canned motor unit 12 passes through the outer peripheral portion of the motor rotor 28 and the front rotor chamber 16 by the action of the auxiliary pump, that is, the auxiliary impeller 32 during the pump operation. , Through the shaft penetrating portion gap 34 and the throttling mechanism 36 provided in the adapter 14, to flow back to the pump portion 10 side. During this period, the circulating fluid is contained in the canned motor unit.
The bearings 26 and 24 are lubricated within the motor 12 and the motor unit 12 is cooled.

However, in the present invention, the canned motor unit 12
A new improvement is added to the auxiliary impeller 32 configured as an auxiliary pump provided inside. In other words, this type of conventional auxiliary impeller generally uses a single-sided open vane with respect to the front bearing in order to simply circulate the circulating fluid efficiently, which facilitates smooth transfer to the pump side and By forming a balance hole in the boss portion of the impeller in parallel with the rotor shaft, the circulating fluid was smoothly supplied to the shaft penetrating portion gap. However, when using a liquid that easily vaporizes or a high temperature liquid as the circulating liquid as in the present invention, simply use the canned motor unit.
Only by improving the circulation of the liquid in the cavities 12, cavitation occurs and the above-mentioned inconvenient problems occur.

Therefore, in the present invention, for example, as shown in FIG. 2, the auxiliary impeller 32 of the closed type blade 40 is used, and the suction port 42 is set to open to the pump portion 10 side. As a result, a desired backflow is generated on the discharge side rear surface of the auxiliary impeller 32, that is, on the front bearing side (indicated by the broken line arrow in FIG. 2), and is always constant even when the suction pressure of the pump section 10 is reduced. Holds the flow path resistance,
The pressure in the canned motor unit 12 can be kept high, and thus the occurrence of cavitation in the canned motor unit 12 can be prevented.

FIG. 3 shows a modified example of the auxiliary impeller 32 that can be effectively applied to the present invention. Instead of the auxiliary impeller 32 shown in FIG. 2, the liquid flow from the suction port 44 to the discharge port 46 is formed at a right angle. A closed type blade 48 configured to deflect in a direction is used. Also in this case, the pressure in the canned motor portion 12 can be kept high and the occurrence of cavitation can be prevented, as in the above-described embodiment.

Further, in the present invention, as the throttle mechanism 36 provided in the shaft penetrating portion gap 34 that communicates the auxiliary pump and the pump portion 10, for example, as shown in FIG. A recess 50 is provided on the peripheral wall surface, and a rotary ring 52 is attached to the rotor shaft 30 corresponding to the recess 50. The outer peripheral portion of the rotary ring 52 is inserted into the recess 50. With such a configuration, in combination with the effect of backflow generated by the auxiliary impeller 32, the shaft penetrating portion gap 34
It is possible to more stably maintain the flow path resistance in, and to further stabilize the pressure retention in the canned motor unit 12 for preventing the occurrence of cavitation described above.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and it is needless to say that various improvements and modifications can be made without departing from the spirit of the present invention. .

[Effect of device]

As is clear from the above-mentioned embodiment, according to the present invention,
An auxiliary pump is installed in the front rotor chamber of the canned motor unit adjacent to the front bearing on the pump unit side, and a liquid equivalent to the pump handling liquid is introduced into the rear rotor chamber from the outside, and this liquid is used to assist the auxiliary pump. A canister for handling an easily vaporized liquid or a high-temperature liquid, which is configured to guide the lubrication of the bearing and cool the motor by being led out to the pump side through the outer peripheral portion of the motor rotor and the front rotor chamber together with the operation of the impeller. In the motor pump, as the auxiliary impeller, a closed type blade having a suction port opened on the pump portion side is used, and the auxiliary pump is configured to generate a desired backflow to the front rotor chamber side. A throttle mechanism is provided in a part of the gap of the shaft penetrating portion of the rotor shaft that communicates the auxiliary pump with the pump chamber so that the pressure level on the rotor chamber side does not drop. By configuring so as to maintain the required flow path resistance, for example, when handling a liquid that is easily vaporized, even when the suction pressure of the pump part is reduced, the auxiliary pump acts on the front rotor chamber side. Required backflow is generated to increase the flow passage resistance in the rotor chamber, whereby the pressure in the rotor chamber of the canned motor unit can be kept sufficiently high, and the occurrence of cavitation in the canned motor unit is effectively prevented. be able to.

Further, according to the present invention, the outflow of the circulating fluid supplied to the canned motor unit to the pump unit side can be extremely reduced, and a smooth and economical pump operation can be realized with a simple configuration.

[Brief description of drawings]

FIG. 1 is a sectional side view of an essential part showing an embodiment of a canned motor pump according to the present invention, and FIG. 2 is a sectional view of an essential part of an auxiliary impeller applied to the canned motor pump according to the present invention. FIG. 3 is a sectional view of the essential part showing another embodiment of the auxiliary impeller, and FIG. 4 is a sectional view of the essential part of the throttle mechanism applied to the canned motor pump according to the present invention. 10 …… Pump part, 12 …… Canned motor part 14 …… Adapter, 16 …… Front rotor chamber 18 …… Rear rotor chamber 20,22 …… Bearing housing 24 …… Front bearing, 26 …… Rear bearing 28 ...... Motor rotor, 30 ...... Rotor shaft 32 …… Auxiliary impeller 34 …… Shaft through gap, 36 …… Throttle mechanism 38 …… Circulating fluid supply system, 40 …… Vane 42 …… Suction port, 44 …… Suction port 46 …… Discharge port, 48 …… Vane 50 …… Recess, 52 …… Rotating ring

Claims (1)

[Scope of utility model registration request] 1. An auxiliary pump is provided in the front rotor chamber of the canned motor unit adjacent to the front bearing on the pump unit side, and a liquid equivalent to the pump handling liquid is introduced into the rear rotor chamber from the outside, and this liquid is supplied. A liquid or a high temperature which is easily vaporized, which is configured to guide the lubrication of the bearing and the cooling of the motor part by operating the auxiliary impeller of the auxiliary pump to be guided to the pump part side through the outer peripheral part of the motor rotor and the front rotor chamber. In a canned motor pump that handles the above liquid, a closed type blade with a suction port opened on the pump side is used as the auxiliary impeller, and the required backflow to the front rotor chamber side is generated by the action of this auxiliary pump. In addition to the above structure, a throttle mechanism is provided in a part of a gap of a shaft penetrating portion of a rotor shaft that connects the auxiliary pump and the pump chamber, and a pressure level on the rotor chamber side is provided. The canned motor pump is configured so as to maintain a required flow path resistance so as not to decrease.