Canned pump

Abstract

To provide a canned pump in which degradation in motor efficiency caused by heat can be prevented.SOLUTION: A canned pump 1 includes a motor part 2 having a stator 21 and a rotor 22, and a pump part 3. A tubular stator can 20 is disposed between a magnet 27 of the rotor 22 and a stator core 24 of the stator 21. A space is formed between the stator core 24 and the stator can 20. The stator can 20 has an annular thin section 20-1 and two thick sections 20-2 extending from the thin section 20-1 to both sides. The thin section 20-1 is thinner than the thick sections 20-2 and has a size occupying a range positioned at least between the stator core 24 and the magnet 27 in the stator can 20.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a canned pump having a structure in which a motor section and a pump section are integrated. [Background technology]

[0002] A canned pump has a structure in which a pump section, such as a centrifugal pump, and a motor section that drives the pump section are integrated. The rotor of the motor section is housed in a cylindrical stator can, and the stator of the motor section is arranged outside the stator can so as to surround the rotor. This means that the stator can is located between the magnet of the rotor and the stator core.

[0003] In order to prevent the presence of such a stator can from increasing eddy current loss and reducing motor efficiency, conventional canned pumps generally use a structure in which the stator core and stator can are in contact with each other, as described in Patent Documents 1 and 2. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2022-7639 A [Patent Document 2] Patent Publication No. 2021-60016 Summary of the Invention [Problem to be solved by the invention]

[0005] Due to the structure of the canned pump, some of the liquid in the pump section flows inside the stator can. Canned pumps are sometimes used to pump low-temperature liquids below 0°C, high-temperature liquids above 100°C, or liquids with large temperature changes, such as liquids with temperature changes between -50°C and +150°C.

[0006] In canned pumps, in which the stator core and the stator can are in contact with each other, the liquid being pumped is low or high temperature, or the temperature of the liquid being pumped changes significantly, which can cause a major problem of thermal influence from the liquid to the stator of the motor section, and from the stator of the motor section to the liquid. In canned pumps, if the stator of the motor section is affected by the temperature of the liquid through the stator can, there is a problem that the motor efficiency decreases. Furthermore, there is also the problem that the stator of the motor section heats up and becomes hot while the canned pump is running, which causes the liquid inside the stator can to be affected by the heat of the stator of the motor section through the stator can.

[0007] Specifically, when the temperature of the liquid circulating inside the stator can is higher than the temperature of the stator of the motor, the heat of the liquid is dissipated to the stator of the motor through the stator can. As a result, the temperature of the stator of the motor rises, and if the heat resistance of the stator of the motor is insufficient, insulation failure may occur. Therefore, the stator of the motor is required to have a heat resistance temperature that takes into account the thermal effect of the liquid, but if a special material with a high heat resistance is used for the stator of the motor, the cost of the canned pump increases. In addition, when the temperature of the liquid circulating inside the stator can is lower than the temperature of the stator of the motor, the heat of the stator of the motor is dissipated to the liquid through the stator can, and the temperature of the liquid rises. When the canned pump is used in equipment for maintaining the temperature of the liquid, such as a temperature regulator, a cooling capacity that takes into account the rise in the temperature of the liquid due to the thermal effect of the stator of the motor is required, which also causes a problem of increased cost of the equipment.

[0008] The present invention aims to provide a canned pump that can suppress the temperature effect on the stator due to the heat of the liquid circulating inside the stator can, and the temperature effect on the liquid circulating inside the stator can due to the heat of the stator, thereby reducing the decrease in motor efficiency. [Means for solving the problem]

[0009] A canned pump according to a first aspect of the present invention includes a motor section having a stator and a rotor, and a pump section, and a cylindrical stator can is disposed between a magnet of the rotor and a stator core of the stator. A space is formed between the stator core and the stator can, and the stator can has an annular thin portion and two thick portions extending from the thin portion on both sides, the thin portions being thinner than the thick portions and having a size that occupies at least the range of the stator can that is located between the stator core and the magnet.

[0010] According to a canned pump having such a configuration, by providing a space between the stator core and the stator can, heat dissipation from the liquid to the stator or from the stator to the liquid can be suppressed. Furthermore, the stator can has an annular thin portion and two thick portions, and the thin portion, which is thinner than the thick portions, has a size that occupies at least the range of the stator can between the stator core and the magnet, thereby ensuring the strength required for the stator can and reducing the decrease in motor efficiency due to eddy current loss.

[0011] In a canned pump according to a second aspect of the present invention, the stator can is made of metal.

[0012] A canned pump according to a third aspect of the present invention includes an outer frame that is fixed to the stator core in a thermally conductive manner and forms a space to accommodate the stator core, and a cooling jacket capable of heat exchange with the outer frame is provided on the outer periphery of the outer frame.

[0013] In the canned pump of the third aspect of the present invention, a cooling jacket capable of exchanging heat with the outer frame is provided on the outer periphery of the outer frame, thereby cooling the motor section from the outer periphery, thereby further reducing heat dissipation from the stator of the motor section to the liquid inside the stator can, and from the liquid inside the stator can to the stator of the motor section. Effect of the Invention

[0014] According to the present invention, a canned pump can be provided that can suppress the temperature effect on the stator of the motor section due to the liquid circulating inside the stator can, and the temperature effect from the stator of the motor section to the liquid circulating inside the stator can, and further reduce the decrease in motor efficiency due to eddy current loss. [Brief description of the drawings]

[0015] [Figure 1] 1 is a partial cross-sectional view of a canned pump according to a first embodiment. FIG. [Diagram 2] FIG. 2 is an enlarged view of part A in FIG. [Diagram 3] 1 is a diagram showing the transfer of heat from the liquid using arrows when the temperature of the liquid inside the stator can is higher than the temperature of the stator of the motor section. [Figure 4] 1 is a diagram showing the transfer of heat from the liquid using arrows when the temperature of the liquid inside the stator can is lower than the temperature of the stator of the motor section. [Diagram 5] FIG. 6 is a partial cross-sectional view of a canned pump according to a second embodiment. [Figure 6] FIG. 6 is an enlarged view of part B in FIG. 5. [Figure 7] 5C is a cross-sectional view taken along line CC of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] A canned pump 1 according to a first embodiment of the present invention will be described below with reference to the drawings. As shown in Fig. 1, the canned pump 1 includes a motor section 2 and a pump section 3 driven by the motor section 2. The canned pump 1 has a structure in which the motor section 2 and the pump section 3 are integrated together.

[0017] The motor section 2 has a stator 21 and a rotor 22. The stator 21 is disposed so as to be located radially outward from the rotor 22. A cylindrical stator can 20 is disposed between the stator 21 and the rotor 22. The rotor 22 is housed inside the stator can 20. It is desirable that the stator can 20 be made of metal in consideration of welding and the like. Specific examples of the material of the stator can 20 include stainless steel and nickel superalloy.

[0018] The stator 21 is composed of a stator core 24 and a plurality of electromagnetic coils 25. The stator can 20 is located inside the stator 21, and a substantially cylindrical outer frame 26 is located outside the stator 21. Both ends of the stator can 20 are connected and fixed to the stator side plates 21a and 21b via members or the like. The outer frame 26 and the stator side plates 21a and 21b are sealed and connected using a seal, welding, or the like. As shown in FIG. 1, the stator 21 is accommodated in a space sealed by the outer frame 26, the stator side plates 21a and 21b, and the stator can 20. The stator core 24 is fixed to the outer frame 26 side with a gap between it and the stator can 20. Since the stator core 24 and the stator can 20 are separated from each other, a space is formed between the stator core 24 and the stator can 20.

[0019] As shown in FIG. 2, the rotor 22 disposed inside the stator can 20 includes a magnet 27, a rotor body 22a, a rotor side plate 22b, a rotor can 22c, a yoke 23, and the like. The rotor 22 is fixed to a rotating shaft 28 and is rotatable. When a driving current is supplied to the stator 21, the rotor 22 and the rotating shaft 28 rotate. The rotor body 22a, the rotor side plate 22b, and the rotor can 22c are joined together by welding. The yoke 23 and the magnet 27 are housed in a sealed state in a space surrounded by the rotor body 22a, the rotor side plate 22b, and the rotor can 22c. The magnet 27 is disposed in a position facing the stator core 24 in the rotor 22.

[0020] As shown in FIG. 1, the pump section 3 has an impeller 31 and a pump casing 32. The impeller 31 is fixed to one end of the rotary shaft 28 and rotates integrally with the rotary shaft 28. An impeller accommodating space 33 in which the impeller 31 is accommodated is formed in the pump casing 32. An inlet 34 is provided on the side of the pump casing 32 in which the impeller 31 is accommodated, through which liquid flows from the outside of the canned pump 1 into the canned pump 1. Also, an outlet 35 is provided on the upper part of the pump casing 32, through which the liquid that has flowed into the canned pump 1 is discharged. A part of the liquid that has flowed into the canned pump 1 flows in the space inside the stator can 20. At this time, the liquid L flows between the stator can 20 and the rotor 22 and circulates.

[0021] As shown in FIG. 1 and FIG. 2, the stator can 20 has a thin portion 20-1 and two thick portions 20-2 extending from the thin portion 20-1 to both sides (left and right sides in FIG. 1 and FIG. 2). The thickness of the thin portion 20-1 is made thinner than the thickness of the thick portion 20-2. The thin portion 20-1 has a size that occupies an area in the stator can 20 between the stator core 24 and the magnet 27. In this embodiment, the thin portion 20-1 of the stator can 20 is formed by recessing a part of the surface of the outside (the stator core 24 side) of the stator can 20 to reduce the thickness. As a result, the cylindrical stator can 20 has an annular recess formed on the surface of the outside (the stator core 24 side). In this way, the stator can 20 is formed by integrating the thin annular thin portion 20-1 and the two thick annular thick portions 20-2 located on both sides of the thin portion 20-1. Thin-walled portion 20-1 may have a size that occupies at least the area between stator core 24 and magnet 27 in stator can 20. It is possible to make it larger than thin-walled portion 20-1 in Figures 1 and 2, and for example, it is possible to make thin-walled portion 20-1 larger on the left and right and thick-walled portion 20-2 smaller in Figures 1 and 2. The thickness of thin-walled portion 20-1 is preferably, for example, 1 mm or less, and is preferably 50% or less of the thickness of thick-walled portion 20-2.

[0022] In this embodiment, the surface of the outside of the stator can 20 (the stator core 24 side) is recessed to partially thin the thickness of the stator can 20 to provide the thin-walled portion 20-1, but the method of providing the thin-walled portion 20-1 on the stator can 20 is not particularly limited. In addition, the steps between both ends of the thin-walled portion 20-1 and the thick-walled portion 20-2 are tapered. The shape of such steps is not particularly limited, and it is also possible to make them gently tapered or curved.

[0023] In the canned pump 1 of this embodiment, a space is provided between the stator core 24 and the stator can 20. When the temperature of the liquid L inside the stator can 20 is higher than the temperature of the stator core 24 of the stator 21, the heat of the liquid L is transferred to the stator can 20, and then transferred to the stator core 24 while being dissipated through the stator side plates 21a, 21b and the outer frame 26 of the motor unit 2, as shown by the black arrows in FIG. 3. In this way, in the canned pump 1 of the present invention, the heat of the liquid L transferred to the stator can 20 is not transferred directly from the stator can 20 to the stator core 24. As a result, the influence of heat on the stator 21 by the liquid L inside the stator can 20 is significantly reduced, and a decrease in motor efficiency due to the heat of the liquid L inside the stator can 20 can be prevented.

[0024] Furthermore, when the temperature of the liquid L inside the stator can 20 is lower than the temperature of the stator core 24 of the stator 21, as shown by the black arrow in Fig. 4, the heat of the stator core 24 is transferred from the stator can 20 to the liquid L while being dissipated to the outside via the outer frame 26 of the motor section 2, etc. In this way, the heat of the stator core 24 of the stator 21 is not directly transferred to the stator can 20, but is transferred to the stator can 20 while being dissipated via other members. As a result, when the heat is transferred from the stator can 20 to the liquid L, the heat of the stator core 24 is significantly reduced, and the problem of the temperature of the liquid L rising due to the thermal effect of the stator 21 of the motor section 2 in the canned pump 1 can be eliminated or mitigated.

[0025] The canned pump 1 of this embodiment not only has a space between the stator core 24 and the stator can 20, but also has a thin-walled portion 20-1 between the stator core 24 and the magnet 27, the stator can 20 being thinner than the thick-walled portion 20-2. By providing the thin-walled portion 20-1 in the stator can 20, the present invention can reduce the decrease in motor efficiency caused by eddy current loss. Furthermore, by providing a thin-walled portion partially having a thin thickness without thinning the entire stator can 20, it is possible to reduce the decrease in motor efficiency caused by eddy current loss while ensuring the strength required for the stator can.

[0026] Next, a canned pump 1A according to a second embodiment will be described. The canned pump 1A of the second embodiment has a configuration in which a cooling jacket 4 is provided to the canned pump 1 of the first embodiment.

[0027] As shown in Fig. 5, the canned pump 1A according to the second embodiment also includes a motor section 2A and a pump section 3 driven by the motor section 2A, similar to the canned pump 1 according to the first embodiment. The motor section 2A has a stator 21 and a rotor 22, and a cylindrical stator can 20A is disposed between the stator 21 and the rotor 22. The stator can 20A is desirably made of metal in consideration of welding and the like. The specific material of the stator can 20A is the same as that of the stator can 20 according to the first embodiment.

[0028] The stator 21 is composed of a stator core 24 and a plurality of electromagnetic coils 25. An outer frame 26A having a substantially cylindrical shape is positioned outside the stator 21. Both ends of the stator can 20A are connected and fixed to the stator side plates 21a and 29. In this embodiment, the stator side plate 29 is integrally formed with the outer frame 26A, and therefore the outer frame 26A and the stator side plate 21a are sealed and connected by sealing, welding, or the like. As shown in FIG. 5, the stator 21 is accommodated in a space sealed by the outer frame 26A, the stator side plates 21a and 29, and the stator can 20A. The stator core 24 is fixed to the outer frame 26A side with a gap therebetween. Since the stator core 24 and the stator can 20A are spaced apart from each other, a space is formed between the stator core 24 and the stator can 20A. The outer frame 26A and the stator side plate 29 may be formed of separate members and fixed by welding or the like.

[0029] The rotor 22 arranged inside the stator can 20A is fixed to a rotating shaft 28 and is rotatable. As shown in Fig. 6, the rotor 22 includes a magnet 27, a rotor body 22a, a rotor side plate 22b, a rotor can 22c, a yoke 23, etc. The yoke 23 and the magnet 27 are housed in a sealed state in a space surrounded by the rotor body 22a, the rotor side plate 22b, and the rotor can 22c.

[0030] As shown in Fig. 5, the pump section 3 has an impeller 31 housed in an impeller housing space 33 and a pump casing 32. An inlet 34 for the inflow of liquid is provided on the side of the pump casing 32, and an outlet 35 for discharging the liquid is provided on the upper part of the pump casing 32. A part of the liquid that has flowed into the canned pump 1A flows through the space inside the stator can 20A. At this time, the liquid L flows between the stator can 20A and the rotor 22 and circulates.

[0031] As shown in FIG. 5 and FIG. 6, the stator can 20A has an annular thin portion 20A-1 and two thick portions 20A-2 extending from the thin portion 20A-1 to both sides (left and right sides in FIG. 5 and FIG. 6). The thickness of the thin portion 20A-1 is thinner than the thickness of the thick portion 20A-2. The thin portion 20-1 has a size that occupies a range between the stator core 24 and the magnet 27 in the stator can 20A. In this embodiment, unlike the first embodiment, in order to form the thin portion 20A-1, a part of the surface on the inside (the magnet 27 side) of the stator can 20A is recessed to reduce the thickness, thereby forming the thin portion 20A-1. As a result, an annular recess is formed on the surface on the inside (the magnet 27 side) of the cylindrical stator can 20A.

[0032] In this way, the stator can 20A is formed by integrating a thin annular thin portion 20A-1 and two thick annular thick portions 20A-2 located on both sides of the thin portion 20A-1. The thin portion 20A-1 has a size that occupies an area between the stator core 24 and the magnet 27 in the stator can 20A. It is possible to make it larger than the thin portion 20A-1 in Figures 5 and 6. For example, it is also possible to make the thin portion 20A-1 larger and the thick portion 20A-2 smaller on the left and right in Figures 5 and 6.

[0033] The method of forming the thin-walled portion 20A-1 of the stator can 20A is not particularly limited, and for example, although not shown, it is possible to provide the thin-walled portion 20A-1 by recessing both the outer and inner surfaces of the stator can 20A to partially reduce the thickness. In this embodiment, the steps between both ends of the thin-walled portion 20A-1 and the other parts are tapered, which allows the liquid L flowing inside the stator can 20A to smoothly pass through the steps.

[0034] As shown in FIG. 5 and FIG. 7, the canned pump 1A of this embodiment is provided with a cooling jacket 4 that can exchange heat with the outer frame 26A in an annular shape along the outer periphery of the outer frame 26A. As shown in FIG. 7, the cooling jacket 4 has an inlet 41 and an outlet 42, and the motor unit 2A is cooled from the outer periphery by circulating a fluid from the inlet 41 to the outlet 42. The motor unit 2A is cooled from the outer periphery by dissipating heat of the fluid that flows out from the outlet 42 and allowing the fluid to flow in again from the inlet 41. As the fluid, a liquid or gas suitable for cooling can be used, and methods such as water cooling and air cooling can be used. The fluid used in the cooling jacket 4 is a fluid that flows through a path different from the liquid pumped by the canned pump 1, and the temperature of the fluid that flows through the cooling jacket 4 is lower than the temperature of the stator core 24, for example, 20 to 50°C. In this way, the canned pump 1A of this embodiment can cool the motor unit 2A from the outer periphery by the cooling jacket 4.

[0035] In the canned pump 1A of this embodiment, the motor section 2A is cooled from the outer periphery, so that heat of the motor section 2A, particularly heat of the stator core 24 of the stator 21 in contact with the outer frame 26A, is dissipated to the fluid circulating through the cooling jacket 4. This makes it possible to suppress a temperature rise in the motor section 2A due to heat generation from the stator core 24 of the stator 21 and the like. By cooling the motor section 2A from the outer periphery by the cooling jacket 4, when the temperature of the liquid L inside the stator can 20A is lower than the temperature of the stator 21 of the motor section 2A, the heat transferred from the stator core 24 of the stator 21 of the motor section 2A to the liquid L inside the stator can 20A is significantly reduced. In particular, in the canned pump 1A of this embodiment, a space is provided between the stator core 24 and the stator can 20A, so that the heat of the stator core 24 is not directly transferred to the stator can 20A but is first transferred to the outer frame 26A. The heat of the stator core 24 transmitted to the outer frame 26A is reduced by heat exchange with the fluid in the cooling jacket 4 and is then transmitted to the stator can 20A via the outer frame 26A etc. As a result, the heat of the stator core 24 is transmitted to the stator can 20A in a significantly reduced state, so that the effect of the heat of the stator core 24 of the stator 21 in the motor section 2A on the liquid L inside the stator can 20 is significantly reduced.

[0036] Furthermore, the cooling jacket 4 can also dissipate heat transferred from the liquid L inside the stator can 20A to the outer frame 26A of the motor section 2A through the stator can 20A. When the temperature of the liquid L inside the stator can 20A is higher than the temperature of the stator 21 of the motor section 2A, the heat of the liquid L circulating inside the stator can 20A is transferred to the stator can 20A, and then transferred to the stator core 24 through the outer frame 26A. At this time, since the cooling jacket 4 is provided on the outer frame 26A, the heat transferred to the outer frame 26A is heat exchanged with the cooling jacket 4 before being transferred to the stator core 24. As a result, the heat transferred to the outer frame 26A is significantly reduced by the cooling jacket 4, and the heat transferred to the stator core 24 is very small. In this way, by providing the cooling jacket 4, the heat dissipation from the liquid L inside the stator can 20A to the stator 21 of the motor section 2A can also be significantly reduced.

[0037] In the canned pump 1A of this embodiment, the stator can 20A has a thin portion 20A-1 between the stator core 24 and the magnet 27, which is thinner than the thick portion 20A-2, and therefore the decrease in motor efficiency due to eddy current loss can be reduced. Furthermore, by providing a thin portion having a small thickness partially without thinning the entire stator can 20A, the strength required for the stator can is ensured while the decrease in motor efficiency due to eddy current loss can be reduced. Furthermore, by providing the thin portion 20A-1 by recessing the inside of the stator can 20A and widening the space between the inner surface of the stator can 20A and the surface of the rotor 22, the flow of the fluid inside the stator can 20A can be made smoother. [Industrial Applicability]

[0038] The present invention can be applied, for example, to a canned pump in which the temperature of the circulating liquid changes. [Explanation of symbols]

[0039] 1,1A canned pump 2,2A motor section 20,20A stator cancel 20-1, 20A-1 Thin section 20-2,20A-2 Thick wall part 21 Stator 21a, 21b, 29 Stator side plate 22 Rotor 22a Rotor body 22b Rotor side plate 22c Rotacan 23 York 24 Stator core 25 Electromagnetic Coil 26,26A Outer frame 27 Magnet 28 Rotational Axis 3. Pump section 31 Impeller 32 Pump casing 33 Impeller housing space 34 Inlet 35 Discharge port 4 Cooling jacket 41 Entrance 42 Exit L liquid

Claims

1. A canned pump includes a motor section having a stator and a rotor, and a pump section, and a cylindrical stator can is disposed between a magnet of the rotor and a stator core of the stator, A space is formed between the stator core and the stator can, The stator can has an annular thin portion and two thick portions extending from the thin portion on both sides, The thin portion is thinner than the thick portion and has a size that occupies at least an area between the stator core and the magnet in the stator can. A canned pump characterized by:

2. The stator can is made of metal.

2. The canned pump according to claim 1.

3. an outer frame that is fixed to the stator can in a thermally conductive manner and forms a space to accommodate the stator core; A cooling jacket capable of exchanging heat with the outer frame is provided on the outer periphery of the outer frame.

3. The canned pump according to claim 1 or 2.

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