JP2017048768A - Canned motor pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively cool a motor stator, which is an important issue in downsizing a motor.SOLUTION: A canned motor pump comprises: a pump part 19 that includes an impeller 20; a motor part 10 that rotates the impeller 20; a motor pressure-proof casing 3 that houses the motor part 10; a can 7 that houses a motor rotor 6 of the motor part 10; and an interior type heat exchanger 14 in contact with an outer peripheral surface of a stator core 4 of the motor part 10. The interior type heat exchanger 14 is arranged in the motor pressure-proof casing 3.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a canned motor pump in which a motor rotor is housed in a can, and more particularly to a canned motor pump including a heat exchanger that cools a motor stator.

  FIG. 8 shows an embodiment of a general canned motor pump. The pump unit 19 includes an impeller 20 and a pump casing 21, and fluid is sucked into the impeller 20 from the suction port 23 of the pump casing 21, and the pressure is increased by the rotation of the impeller 20. It is pumped from the outlet 25 to the outside of the pump. The impeller 20 is rotated by the motor unit 10. The motor unit 10 includes a motor rotor 6 and a motor stator 1. The impeller 20 is coupled to a rotating shaft 28 to which the motor rotor 6 is fixed. The rotary shaft 28 is rotatably supported by a thrust bearing 31 and radial bearings 32 and 33 provided in the motor pressure-resistant casing 3.

  The motor rotor 6 generates a rotational force by an electromagnetic action generated by the motor stator 1 provided inside the motor pressure-resistant casing 3. The motor stator 1 has a stator core 4 having a large number of axial slots and a motor coil 2 housed in the axial slots. The motor stator 1 generates a rotating magnetic field by supplying electric power to the motor coil 2 from the outside.

  A thin cylindrical metal can 7 is provided between the motor rotor 6 and the motor stator 1. The motor rotor 6 is disposed inside the can 7 and the motor rotor 6 is immersed in the motor cooling fluid. The motor cooling fluid is generated by cooling a part of the fluid pressurized by the pump unit 19. Specifically, a part of the fluid pressurized by the pump unit 19 is introduced into the external heat exchanger 35 and cooled by external cooling water flowing through the external heat exchanger 35. The fluid exiting the external heat exchanger 35 is introduced into the can 7 as a motor cooling fluid. The motor cooling fluid passes through the thrust bearing 31 and the radial bearing 32 and flows into the can 7, and further passes through the inside of the can 7 and the radial bearing 33 to be returned to the pump unit 19.

  A sealed space is formed between the can 7 and the motor pressure-resistant casing 3, and the motor stator 1 is disposed in this sealed space. By providing the can 7 functioning as a partition inside the motor stator 1, intrusion of the motor cooling fluid into the motor stator 1 is prevented. Even if the can 7 is broken and the motor stator 1 is immersed in the motor cooling fluid, the motor pressure-resistant casing 3 is a pressure-resistant container that can withstand the pressure of the motor cooling fluid so that the motor cooling fluid does not leak out of the pump. Designed.

  Since the canned motor pump rotates with the motor rotor 6 immersed in the motor cooling fluid, friction loss occurs between the motor cooling fluid and the motor rotor 6, and the rotation generated by the motor stator 1 occurs. Since eddy current loss occurs when the magnetic field crosses the metal can 7, the efficiency as a pump is inferior to that of a general mechanical seal type pump. Therefore, the canned motor pump is often used for special purposes such as when hazardous liquids such as dangerous liquids are particularly disliked or when the pressure of the fluid pressurized by the impeller 20 is high and it is difficult to apply a mechanical seal. .

JP 2002-257075 A

  In the canned motor pump, mechanical and electromagnetic losses generated in the motor rotor 6, the bearings 31, 32, 33, the can 7 and the like are transmitted to the motor cooling fluid around the motor rotor 6. Generally, a cooling mechanism is provided to suppress the temperature rise. In the example of FIG. 8, a part of the fluid pressurized by the impeller 20 is led to an external heat exchanger 35 provided outside the pump, cooled to an appropriate temperature with external cooling water, and then the motor cooling fluid of the motor end cover 5. It leads to the injection hole 5b.

  After cooling the thrust bearing 31 and the radial bearing 32 of the motor rotor 6, the motor cooling fluid removes the generated heat when passing through the gap between the motor rotor 6 and the inner peripheral surface of the can 7. The two radial bearings 33 are finally passed back to the pump casing 21. A part of the heat generated due to the electric loss generated in the motor stator 1 and the motor coil 2 is cooled by the motor cooling fluid via the can 7 arranged inside thereof, but the remaining heat is supplied from the motor pressure-resistant casing 3. Must be released to the surrounding atmosphere. At this time, if heat cannot be removed by heat radiation by natural convection to the surrounding atmosphere, a jacket cooler 36 may be provided on the outer peripheral surface of the peripheral wall 3a of the motor pressure-resistant casing 3 to cool the motor pressure-resistant casing 3 (for example, Patent Documents). 1).

  However, since the motor pressure-resistant casing 3 of the canned motor pump is designed as a pressure-resistant container that can withstand the pressure even when the motor cooling fluid leaks as described above, the peripheral wall 3a of the motor pressure-resistant casing 3 is thick. Is formed. For this reason, it is difficult to efficiently cool the motor stator 1 by the jacket cooler 36. In particular, the coil end portions 2a at both ends of the motor portion 10 are covered with an insulating material, and in order to cool the coil end portion 2a to a temperature lower than the heat resistance temperature of the insulating material, it is necessary to provide a large jacket cooler. As a result, the entire motor was large.

  As described above, in the case of a canned motor pump, the cooling of the heat generated by the motor is one of the most important technical issues from the viewpoint of limiting the heat-resistant temperature of the coil insulating material. It is a rule condition in

  The present invention relates to motor cooling of the above-described canned motor pump, and particularly aims to efficiently cool the motor stator, which is an important issue in miniaturizing the motor.

  In order to achieve the above-described object, one aspect of the present invention provides a pump unit having an impeller, a motor unit that rotates the impeller, a motor pressure-resistant casing that houses the motor unit, and a motor of the motor unit. A can for housing a rotor and an internal heat exchanger in contact with an outer peripheral surface of a stator core of the motor unit, wherein the internal heat exchanger is disposed in the motor pressure-resistant casing. It is a canned motor pump.

In a preferred aspect of the present invention, the internal heat exchanger is in contact with an inner peripheral surface of a peripheral wall of the motor pressure-resistant casing.
In a preferred aspect of the present invention, the internal heat exchanger has an inner wall contacting the outer peripheral surface of the stator core, and the inner wall of the internal heat exchanger is thinner than the peripheral wall of the motor pressure-resistant casing. It is characterized by.
In a preferred aspect of the present invention, the internal heat exchanger extends to positions opposed to coil end portions at both end portions of the motor portion.

In a preferred aspect of the present invention, the motor unit includes a plurality of inner air guide passages and a plurality of outer air guide passages that penetrate the stator core in the axial direction, and the inner air guide passage is a motor of the motor unit. It is located near the coil, and the outer air guide passage is formed on the outer peripheral surface of the stator core.
In a preferred aspect of the present invention, the internal heat exchanger has a flow path through which a coolant flows, and the flow path is formed between a plurality of ribs.
In a preferred aspect of the present invention, the flow path extends in a spiral shape.

In a preferred aspect of the present invention, the coil end chamber in which the coil end portion of the motor unit is accommodated is filled with a dried inert gas.
In a preferred aspect of the present invention, the coil end chamber in which the coil end portion of the motor unit is accommodated is filled with a liquid inert refrigerant.
In a preferred aspect of the present invention, the inert refrigerant is fluorinate.

  Since the internal heat exchanger is accommodated in the motor pressure-resistant casing, it is not necessary to configure the internal heat exchanger itself as a pressure-resistant container. Therefore, since the inner wall of the internal heat exchanger can be made very thin, the internal heat exchanger can cool the motor stator efficiently by the coolant flowing through the internal heat exchanger. Moreover, the internal heat exchanger directly contacts the gas in the coil end chamber, which is a sealed space formed in the motor pressure-resistant casing, generates natural convection of the gas, and efficiently cools the coil end portion of the motor coil. be able to.

It is a figure showing a 1st embodiment of a canned motor pump concerning the present invention. It is the sectional view on the AA line of FIG. It is a schematic diagram which shows the cross section of an interior type heat exchanger. It is an expanded view which shows the flow path shown in FIG. It is a figure which shows 2nd Embodiment of the canned motor pump which concerns on this invention. FIG. 6 is a sectional view taken along line B-B in FIG. 5. It is a figure which shows 3rd Embodiment of the canned motor pump which concerns on this invention. It is a figure which shows one form of a common canned motor pump.

  Embodiments of the present invention will be described below with reference to the drawings. Since the configuration of the present embodiment not specifically described is the same as the configuration of the canned motor pump shown in FIG. 8, the same or corresponding elements are denoted by the same reference numerals, and redundant description thereof is omitted.

  FIG. 1 is a view showing a first embodiment of a canned motor pump according to the present invention, FIG. 2 is a cross-sectional view taken along line AA of FIG. An internal heat exchanger 14 is provided inside the motor pressure-resistant casing 3 that houses the motor stator 1. This internal heat exchanger 14 has a flow path 15 through which a coolant flows, and directly cools the motor stator 1. As shown in FIG. 2, the internal heat exchanger 14 has a plurality of flow paths 15 through which the coolant flows. These flow paths 15 are formed between a plurality of ribs 16, and the ribs 16 are provided between the inner wall 17 and the outer wall 18 of the internal heat exchanger 14. The inner wall 17 and the outer wall 18 are cylindrical.

  The internal heat exchanger 14 is in direct contact with the outer peripheral surface of the stator core 4 and is cooled as compared with the case where it is cooled via the peripheral wall 3a of the motor pressure-resistant casing 3 like the jacket cooler 36 of FIG. Efficiency can be increased. The internal heat exchanger 14 is disposed with the motor stator 1 in the motor pressure-resistant casing 3.

  The internal heat exchanger 14 has a cylindrical shape. The inner peripheral surface of the internal heat exchanger 14 (that is, the inner peripheral surface of the inner wall 17) is in contact with the outer peripheral surface of the stator core 4, and the outer peripheral surface of the internal heat exchanger 14 (that is, the outer peripheral surface of the outer wall 18) is The motor pressure-resistant casing 3 is in contact with the inner peripheral surface of the peripheral wall 3a. The outer peripheral surface of the can 7 is in contact with the inner surface of the stator core 4. Therefore, the pressure of the motor cooling fluid flowing inside the can 7 is supported by the peripheral wall 3 a of the motor pressure-resistant casing 3 through the can 7, the stator core 4, and the internal heat exchanger 14.

  Here, if the thickness of the peripheral wall 3a of the motor pressure-resistant casing 3 is Tm, the internal pressure is P, the inner diameter of the motor pressure-resistant casing 3 is D, and the allowable stress of the material of the motor pressure-resistant casing 3 is S, the peripheral wall 3a of the motor pressure-resistant casing 3 The thickness Tm can be expressed by the formula Tm = P × D / (2S). For example, if P = 10 MPa, D = 1000 mm, and S = 100 MPa, the thickness Tm of the peripheral wall 3a of the motor pressure-resistant casing 3 is 50 mm.

  Since the outer peripheral surface of the internal heat exchanger 14 is supported by the inner peripheral surface of the peripheral wall 3a of the motor pressure-resistant casing 3, when the number of ribs 16 between the flow paths 15 is sufficient, the internal heat exchanger 14 The inner wall 17 can be very thin. For example, in the case of the above conditions, it is sufficient that the thickness tc of the inner wall 17 of the internal heat exchanger 14 is about 3 mm to 5 mm.

  According to the well-known Fourier heat transfer equation, the heat removal amount of the heat exchanger is approximately inversely proportional to the wall thickness. If the heat removal amount of the jacket cooler 36 shown in FIG. 8 is Qj and the heat removal amount of the internal heat exchanger 14 is Qi, then Qi / Qj∝Tm / tc. According to the above example, when the thickness Tm of the peripheral wall 3a of the motor pressure-resistant casing 3 is 50 mm and the thickness tc of the inner wall 17 of the internal heat exchanger 14 is 3 mm to 5 mm, Tm / tc ≧ 10, and the heat exchange ratio is 10 times or more.

  Thus, since the thickness tc of the inner wall 17 of the internal heat exchanger 14 can be made much smaller than the thickness Tm of the peripheral wall 3a of the motor pressure-resistant casing 3, the heat removal amount Qi of the internal heat exchanger 14 is equal to the jacket. The heat removal amount Qj of the cooler 36 can be made much larger. That is, since the internal heat exchanger 14 can cool the motor stator 1 more strongly than the jacket cooler 36 shown in FIG. 8, the motor can be downsized accordingly.

  By configuring the flow path 15 through which the cooling liquid of the internal heat exchanger 14 flows in a number of axially extending flow paths or one or more spiral flow paths, the circumferential cooling distribution of the internal heat exchanger 14 is increased. In addition to being uniform, the necessary mechanical strength can be provided by the reinforcing effect of the ribs 16 between the flow paths 15. FIG. 3 is a schematic view showing a cross section of the internal heat exchanger 14, and FIG. 4 is a development view showing the flow path 15 shown in FIG. 3 and 4 schematically show the flow path 15 of the internal heat exchanger 14 and are different from the dimensions in FIGS. 1 and 2.

  As shown in FIGS. 3 and 4, the plurality of flow paths 15 extend in a spiral shape. Both ends of each flow path 15 are connected to an inlet side header 41 and an outlet side header 42, respectively. The inlet-side header 41 is connected to the coolant inlet 43, and the outlet-side header 42 is connected to the coolant outlet 44. The coolant flows into the inlet side header 41 through the inlet 43, and further flows through the spiral flow paths 15 from the inlet side header 41. The coolant that has flowed through the respective flow paths 15 merges in the outlet-side header 42, passes through the outlet 44, and is discharged to the outside of the internal heat exchanger 14. Instead of the plurality of spiral channels 15, a single spiral channel 15 may be formed.

  One of the effects of adopting the internal heat exchanger 14 is that the coil end portion 2a of the motor coil 2 that has been difficult to cool so far and has become a rule for determining the heat-resistant insulation grade of the motor. To allow cooling. That is, the internal heat exchanger 14 extends to a position facing the coil end portions 2 a at both ends of the motor stator 1. With this configuration, the gas in the coil end chamber 8 heated by the high temperature coil end portion 2a rises, travels along the inner surface of the motor pressure-resistant casing 3, reaches the internal heat exchanger 14, and is cooled there. And return to the coil end portion 2a again. It is possible to suppress the temperature rise of the coil end portion 2a by positively generating such convection cooling by the circulating gas in the coil end chamber 8.

  FIG. 5 is a view showing a second embodiment of the canned motor pump according to the present invention, and FIG. 6 is a cross-sectional view taken along the line BB of FIG. A plurality of inner air guide passages 51 are provided in the stator core 4 near the motor coil 2 that is a heat source. A plurality of outer air guide passages 52 are formed on the outer peripheral surface of the stator core 4, that is, on the portion where the stator core 4 is in contact with the internal heat exchanger 14. The inner air guide passage 51 and the outer air guide passage 52 extend in the axial direction of the motor unit 10 and penetrate the stator core 4. The inner air guide passage 51 and the outer air guide passage 52 may be round holes or polygon holes.

  One coil end chamber 8 and the other coil end chamber 8 are connected by an inner air guide passage 51 and an outer air guide passage 52. Therefore, when the canned motor pump is installed vertically, an upward flow is generated in the inner air guide passage 51 in the vicinity of the high-temperature motor coil 2 and a lower flow is generated in the outer air guide passage 52 in the vicinity of the low-temperature internal heat exchanger 14. Since a flow is generated, as shown by an arrow in FIG. 5, a gas circulation flow that circulates between the lower coil end chamber 8 and the upper coil end chamber 8 is formed. The motor stator 1, the motor coil 2, and the coil end portion 2 a can be further efficiently cooled by this gas circulation flow.

  The gas filled in the coil end chamber 8 is generally air. However, in the case of air having moisture, condensation occurs when heated by the motor stator 1 and then cooled by the internal heat exchanger 14. Dry air or, more preferably, a dry inert gas such as nitrogen or argon is preferred because it may occur. In addition, the coil end chamber 8 is filled with an inert refrigerant having a property of evaporating at an appropriate temperature lower than the heat resistance temperature of the insulating material covering the coil end portion 2a, which is liquid at room temperature and normal pressure such as florinate instead of gas. May be. Since the inert refrigerant can remove the latent heat of vaporization when heated and evaporated in the inner air guide passage 51 provided in the motor stator 1, the cooling effect can be further enhanced. The evaporated inert refrigerant is cooled by the internal heat exchanger 14 and returned to the liquid again, so that the loop thermosyphon cooling cycle is maintained.

  Since the internal heat exchanger 14 is accommodated in the motor pressure-resistant casing 3, it is not necessary to configure the internal heat exchanger 14 itself as a pressure vessel. Therefore, since the wall 17 forming the flow path 15 of the internal heat exchanger 14 can be made very thin, the internal heat exchanger 14 can efficiently cool the motor stator 1 by the coolant flowing inside. . Moreover, the internal heat exchanger 14 directly contacts the gas in the coil end chamber 8 that is a sealed space formed in the motor pressure-resistant casing 3 to generate natural convection of the gas, and the coil end portion of the motor coil 2. 2a can be efficiently cooled.

  FIG. 7 is a view showing a third embodiment of the canned motor pump according to the present invention. In the present embodiment, both end portions of the internal heat exchanger 14 protrude inward in the radial direction and are brought close to the coil end portion 2a. Therefore, the internal heat exchanger 14 can cool the coil end portion 2a more efficiently.

  The embodiment described above is described for the purpose of enabling the person having ordinary knowledge in the technical field to which the present invention belongs to implement the present invention. Various modifications of the above embodiment can be naturally made by those skilled in the art, and the technical idea of the present invention can be applied to other embodiments. Accordingly, the present invention is not limited to the described embodiments, but is to be construed in the widest scope according to the technical idea defined by the claims.

DESCRIPTION OF SYMBOLS 1 Motor stator 2 Motor coil 2a Coil end part 3 Motor pressure | voltage resistant casing 3a Perimeter wall 4 Stator core 5 Motor end cover 5b Motor cooling fluid injection hole 6 Motor rotor 7 Can 8 Coil end chamber 10 Motor part 14 Interior type heat exchanger 15 Flow path 16 Rib 17 Inner wall 18 Outer wall 19 Pump part 20 Impeller 21 Pump casing 23 Suction port 25 Discharge port 28 Rotating shaft 31 Thrust bearing 32, 33 Radial bearing 35 External heat exchanger 36 Jacket cooler 41 Inlet side header 42 Outlet side header 43 Entrance 44 Exit

Claims (10)

A pump unit having an impeller;
A motor unit for rotating the impeller;
A motor pressure-resistant casing for housing the motor unit;
A can for accommodating a motor rotor of the motor unit;
An internal heat exchanger in contact with the outer peripheral surface of the stator core of the motor unit,
The canned motor pump, wherein the internal heat exchanger is disposed in the motor pressure-resistant casing.   The canned motor pump according to claim 1, wherein the internal heat exchanger is in contact with an inner peripheral surface of a peripheral wall of the motor pressure-resistant casing.   The internal heat exchanger has an inner wall that contacts an outer peripheral surface of the stator core, and the inner wall of the internal heat exchanger is thinner than the peripheral wall of the motor pressure-resistant casing. Or the canned motor pump of 2.   The canned motor pump according to any one of claims 1 to 3, wherein the internal heat exchanger extends to a position opposite to coil end portions at both ends of the motor portion.   The motor unit has a plurality of inner air guide passages and a plurality of outer air guide passages that pass through the stator core in the axial direction, and the inner air guide passages are located near the motor coil of the motor unit. The canned motor pump according to any one of claims 1 to 4, wherein the outer air guide passage is formed on an outer peripheral surface of the stator core.   5. The internal heat exchanger has a flow path through which a cooling liquid flows, and the flow path is formed between a plurality of ribs. The described canned motor pump.   The canned motor pump according to claim 6, wherein the flow path extends in a spiral shape.   The canned motor pump according to any one of claims 1 to 7, wherein the coil end chamber in which the coil end portion of the motor unit is accommodated is filled with a dried inert gas.   The canned motor pump according to any one of claims 1 to 7, wherein the coil end chamber in which the coil end portion of the motor unit is accommodated is filled with a liquid inert refrigerant.   The canned motor pump according to claim 9, wherein the inert refrigerant is Fluorinert.

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