JP2015025429A - Submersible motor pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a submersible motor pump that can be used in an environment where corrosion resistance is required.SOLUTION: A submersible motor pump 10 comprises a motor part 20, a pump part 30, and an outside casing 51. The motor part 20 comprises a metal motor casing 21 and a motor shaft 22 protruding from a bottom surface of the motor casing 21. The pump part 30 comprises a resin pump impeller 31 connected to the motor shaft 22 and a resin pump casing 32 for housing the pump impeller 31. The outside casing forms a housing space 50A for surrounding the motor part 20 and housing the motor part 20, and cooling liquid 45 is enclosed in the housing space 50A.

Description

  The present invention relates to a submersible motor pump, and more particularly to a submersible motor pump that requires corrosion resistance.

  When a submersible motor pump is used in a corrosive liquid such as seawater, the metal part is corroded, so that the life of the submersible motor pump is significantly reduced. For this reason, it has been studied to make the liquid contact portion of the submersible motor pump as resin as possible (for example, see Patent Document 1).

Japanese Utility Model Laid-Open No. 5-14590 JP 2002-310088 A

  However, at present, it is difficult to completely convert the submersible motor pump into a resin. In particular, if the motor casing is made of resin, the strength may be insufficient and it may be damaged. Further, since the resin has a lower thermal conductivity than the metal, the resin cannot sufficiently dissipate heat, and the motor may be damaged by heat.

  It is also conceivable that the motor casing is not made of resin, but is formed of a titanium alloy or the like having high corrosion resistance. However, titanium alloys are more expensive than common metal materials such as stainless steel. Also, processing is difficult. For this reason, there is a problem that the cost of the submersible motor pump is greatly increased.

  A method of cooling the motor so that the pumped liquid and the motor casing are not in contact with each other has been studied (for example, see Patent Document 2). However, this is a technique for enabling continuous operation in the air. No consideration has been given to handling corrosive liquids.

  An object of the present disclosure is to solve the above-described problem and to realize a submersible pump that can be used in an environment where corrosion resistance is required.

  One aspect of the submersible motor pump of the present disclosure includes a motor unit having a metal motor casing, a motor shaft protruding from the bottom surface of the motor casing, a resin pump impeller coupled to the motor shaft, and a pump blade. A pump part having a resin pump casing for housing a car, a resin outer casing that surrounds the motor part and forms a housing space for housing the motor part, and a cooling liquid sealed in the housing space Yes.

  In one aspect of the submersible motor pump, the motor pump further includes a shaft seal device that is provided between the motor casing and the pump unit and seals the motor shaft, and the housing space includes a first space that surrounds the side surface of the motor casing, and a shaft seal. A second space surrounding the device, the first space and the second space may be independent from each other, and the cooling liquid may be sealed in the first space.

  In addition, a shaft seal device that is provided between the motor casing and the pump unit and seals the motor shaft is further provided, and the accommodation space includes a first space that surrounds the side surface of the motor casing, and a second space that surrounds the shaft seal device. The first space and the second space communicate with each other, and the coolant may function as a lubricant for the shaft seal device.

  In this case, the coolant may be in contact with the side surface of the motor casing and the top surface of the second space.

  Moreover, it is good also as a structure further provided with the rotary blade which is provided in 2nd space and stirs a cooling liquid by rotating with a motor shaft.

  In one aspect of the submersible motor pump, the motor shaft may be titanium or a titanium alloy.

  In one aspect of the submersible motor pump, the motor unit may include a stator, and a ratio of a length of the starter in the motor axial direction to a length of the motor casing in the motor axial direction may be 0.5 or less.

  One aspect of the submersible motor pump may further include an inverter that controls the motor unit, and the inverter may be configured to control the motor unit so as to reduce a change in power consumption accompanying a change in discharge amount.

  The submersible motor pump according to the present disclosure can be used in an environment where corrosion resistance is required.

It is sectional drawing which shows the submersible motor pump which concerns on one Embodiment. It is sectional drawing which shows the modification of the submersible motor pump which concerns on one Embodiment. It is a fragmentary sectional view showing the modification of the submersible motor pump concerning one embodiment.

  Hereinafter, an embodiment of a submersible motor pump will be described based on the drawings. The following description of the preferred embodiment is merely exemplary in nature.

  FIG. 1 shows a configuration of a submersible motor pump 10 of the present embodiment. As shown in FIG. 1, the submersible motor pump 10 includes a motor unit 20 and a pump unit 30. The motor unit 20 has a cylindrical motor casing 21 that is open on one side. Inside the motor casing 21, a stator 24 and a rotor 27 including a permanent magnet 26 are provided. The rotor 27 is integrated with the motor shaft 22. One end of the motor shaft 22 is held by a bearing 71. The bearing 71 is fixed to a bearing bracket 28 that serves as a lid of the motor casing 21. The other end of the motor shaft 22 penetrates the bottom surface of the motor casing 21 and extends to the pump unit 30 side. A bearing 72 is provided on the bottom surface of the motor casing 21 and holds the motor shaft 22.

  The motor casing 21 is made of metal. Among these, stainless steel is preferable from the viewpoint of thermal conductivity, strength, corrosion resistance, price, and the like. The motor casing 21 can be formed by press working or the like. The motor casing 21 can also be formed by other methods. The bearing bracket 28 is not particularly limited, but may be formed by aluminum die casting or the like. If the required strength is obtained, the bearing bracket 28 may be formed of resin. The motor shaft 22 is not particularly limited, but can be made of titanium or a titanium alloy having excellent corrosion resistance. Moreover, it can also form with materials, such as a ceramic.

The pump unit 30 includes a pump impeller 31 connected to the motor shaft 22 and a pump casing 32 that houses the pump impeller 31. The pump impeller 31 is made of resin, and may be, for example, polyphenylene sulfide (PPS), urethane rubber, glass fiber reinforced resin, acrylonitrile-butadiene-styrene copolymer (ABS), polyamide (PA), or the like. The pump casing 32 is made of resin, and can be, for example, PPS, glass fiber reinforced resin, ABS, PA, or the like . The pump casing 32 includes an upper pump casing 32A and a lower pump casing 32B. The pump casing 32 has a suction port 35a that is a suction port for pumped liquid and a discharge port 35b that discharges the pumped liquid. A companion flange 37 for pipe connection is attached to the discharge port 35b as necessary.

  A shaft seal device 41 that seals the motor shaft 22 is provided between the pump unit 30 and the motor casing 21. The shaft sealing device 41 prevents water from entering the motor casing 21. The shaft seal device 41 is not particularly limited, but a mechanical seal can be used. An oil seal, a gland packing, or the like can also be used.

A motor cover 53 is provided on the side of the motor unit 20 opposite to the pump unit 30. The motor cover 53 is resinous and can be, for example, PPS, glass fiber reinforced resin, ABS, PA, or the like . An inverter 61 is accommodated in a space formed between the motor cover 53 and the bearing bracket 28. The inverter 61 controls the operation of the motor unit 20. Electric power is supplied to the inverter 61 through a cable 62. The part where the cable 62 penetrates the motor cover 53 is sealed.

  An outer casing 51 that houses the motor unit 20 is provided between the pump unit 30 and the motor cover 53. The outer casing 51 is resinous and can be, for example, PPS, glass fiber reinforced resin, ABS, PA, or the like.

  In FIG. 1, the outer casing 51 has a cylindrical shape with both ends opened, and has a partition wall 51A therebetween. The first space 50 </ b> A between the motor cover 53 and the partition wall 51 </ b> A surrounds the side surface of the motor casing 21. The coolant 45 of the motor casing 21 is sealed in the first space 50A. The cooling liquid 45 is not particularly limited, but water can be used. The cooling liquid 45 may contain a rust preventive agent or the like. The second space 50B between the upper pump casing 32A and the partition wall 51A is independent of the first space 50A. The second space 50 </ b> B surrounds the shaft seal device 41. FIG. 1 shows a configuration in which the shaft seal device 41 is a mechanical seal, and the second space 50B is a lubricant box in which the lubricant 46 of the shaft seal device 41 is sealed. The lubricant 46 may be selected according to the shaft seal device 41. For example, oil or the like can be used. The lubricant 46 may or may not completely fill the second space 50B. Further, depending on the configuration of the shaft seal device 41, the lubricant 46 may not be sealed in the second space 50B.

  Since the underwater motor pump 10 of the present embodiment is provided with the outer casing 51, the metal motor casing 21 does not come into contact with the pumped liquid. Therefore, the underwater motor pump 10 can be used even in an environment where the pumped liquid is a corrosive liquid such as seawater. A coolant 45 is sealed in the first space 50 </ b> A between the outer casing 51 and the motor casing 21. For this reason, the heat generated in the motor unit 20 is quickly transferred from the motor casing 21 to the coolant 45, transferred from the coolant 45 to the outer casing 51, and from the outer casing 51 to the pumped liquid existing around the submersible motor pump 10. It is transmitted. Therefore, the motor unit 20 can be efficiently cooled.

  Most of the heat in the motor unit 20 is generated in the stator 24. Since the stator 24 is in contact with the motor casing 21, the heat generated in the stator 24 is transmitted to the motor casing 21. However, when the motor casing 21 is made of resin, the heat conductivity is low, so that heat stays in the portion of the motor casing 21 that is in contact with the stator 24. For this reason, even if the motor casing 21 is in direct contact with the pumped liquid, heat can be radiated only from a narrow range of the motor casing 21.

  On the other hand, in the present embodiment, since the motor casing 21 is made of metal, heat spreads quickly over the entire motor casing 21. Since a wide range of the side surface of the motor casing 21 is in contact with the coolant 45, heat transfer from the motor casing 21 to the coolant 45 also occurs in a wide range. Furthermore, heat transfer from the coolant 45 to the outer casing 51 also occurs in a wide range, and heat is transmitted to the wide range of the outer casing 51. As a result, even if the outer casing 51 is resin, heat can be efficiently transferred to the pumped liquid surrounding the submersible motor pump 10. In addition, from the viewpoint of heat dissipation, it is preferable to operate in a state where the pumped liquid surrounds the outer casing 51, but it is also possible to operate in a state where the outer casing 51 is exposed to the air.

  The coolant 45 is not particularly limited, and water, oil, an organic solvent, or the like can be used. From the viewpoint of heat dissipation efficiency, water that has high thermal conductivity and is easy to handle is preferable. A rust preventive or anticorrosive may be added to the water.

  The amount of the cooling liquid 45 is not particularly limited, but is preferably large from the viewpoint of heat dissipation efficiency. For example, it is preferable to fill the coolant 45 to a position higher than the position of the stator 24 in the motor casing 21.

  In the submersible motor pump 10 shown in FIG. 1, the first space 50A and the second space 50B formed by the outer casing 51 are independent of each other. However, as shown in FIG. 2, the submersible motor pump 10A may be provided with a passage connecting the first space 50A and the second space 50B. In this case, the coolant 45 is also filled in the second space 50B. The coolant 45 can be a liquid that functions as a lubricant for the shaft seal device 41. When the coolant 45 is oil, the thermal conductivity is lower than that of water. However, there is an advantage that the amount of the cooling liquid 45 is increased and heat can be radiated from a wide range. In addition, there is an advantage that heat is radiated from the lower part of the outer casing 51 and the partition between the second space 50B and the pump unit 30 (upper pump casing 32A). If a mechanical seal capable of using an aqueous lubricant is used, an aqueous coolant can be used even when the first space 50A and the second space 50B communicate with each other.

  When communicating the first space 50A and the second space 50B, as shown in FIG. 3, a stirring blade 75 is provided in the second space 50B in order to forcibly circulate the cooling liquid 45. Also good. By rotating the stirring blade 75 by the motor shaft 22, the cooling liquid 45 is forcibly circulated, and the cooling efficiency is further improved. However, even when the stirring blade 75 is not provided, the cooling liquid 45 is always mixed by convection, so there is no problem even if the stirring blade 75 is not provided.

  When the first space 50A and the second space 50B are communicated with each other, the cooling liquid 45 can be in contact with the top surface (the lower surface of the partition wall 51A) of the second space 50B. Since the cooling liquid 45 is in contact with the top surface of the second space 50B, heat radiation from the bottom surface of the motor casing 21 can also be promoted.

  The submersible motor pumps 10 and 10A of the present embodiment can dissipate heat efficiently, but it is preferable to use an efficient permanent magnet synchronous motor from the viewpoint of reducing heat generation itself. In particular, it is preferable to use a motor having a motor efficiency of 95% or more. However, an induction motor can also be used. When the induction motor is used, the inverter 61 may not be provided. In the permanent magnet synchronous motor, the axial length (height) l of the stator 24 may be large, but it is preferable that l is small from the viewpoint of weight reduction of the motor. When the axial length l of the stator 24 is small, for example, the ratio l / L of the axial length l of the stator 24 to the axial length (height) L of the motor casing 21 is 0.5 or less. In this case, the improvement of the cooling efficiency can be expected especially by the configuration of the present embodiment. The axial length l of the stator 24 is the length of the portion of the stator 24 that is in contact with the motor casing 21.

  The output of the motor unit 20 may be selected in accordance with the required characteristics of the submersible pump, but a higher effect can be expected at 250 W or more where sufficient cooling is required. Moreover, since cooling efficiency is lower than the structure where a metal motor casing is directly in contact with the pumped liquid, 2.2 kW or less is preferable.

  In the case of a submersible pump, the power consumption is generally not constant from the deadline state to the open state, and the power consumption varies greatly depending on the use conditions. However, since the thermal and electrical capacities are designed in accordance with the peak value, even if there is a surplus in the amount of heat generated under the condition of low power consumption, the surplus cannot be used. Since the submersible motor pumps 10 and 10A of the present embodiment are equipped with the inverter 61, the inverter 61 suppresses the power consumption in the operation state where the power consumption is large, and reduces the change in the power consumption due to the change in the operation condition. , It can be controlled to be almost constant. Thereby, the emitted-heat amount of the motor part 20 can be made substantially constant irrespective of use conditions, and an underwater motor pump can be drive | operated efficiently. A method for making the power consumption constant is not particularly limited, but a method for controlling the rotation of the motor in accordance with a correspondence table of current values and frequencies created in advance can be used.

  In the submersible motor pumps 10 and 10 </ b> A of the present embodiment, an example in which the first space 50 </ b> A is formed by the outer casing 51 and the motor cover 53 is shown. However, the outer casing 51 may be further raised so that the outer casing 51 covers the motor cover 53. In this case, a lid that covers the opening of the outer casing 51 may be provided. In addition, the portion of the outer casing 51 that forms the first space 50A and the portion that forms the second space 50B may be separated. The outer casing 51 and the motor cover 53 may be integrated. When the inverter 61 is not necessary, the motor cover 53 may not be provided, and the upper surface of the bearing bracket 28 may be in contact with the coolant 45.

  In the submersible motor pump of this embodiment, the bolts and nuts of the liquid contact part may be made of titanium or a titanium alloy.

  The submersible motor pump of the present disclosure can be used in an environment where corrosion resistance is required while efficiently dissipating heat, and is useful as a submersible motor pump.

DESCRIPTION OF SYMBOLS 10 Submersible motor pump 10A Submersible motor pump 20 Motor part 21 Motor casing 22 Motor shaft 24 Stator 26 Permanent magnet 27 Rotor 28 Bearing bracket 30 Pump part 31 Pump impeller 32 Pump casing 32A Upper pump casing 32B Lower pump casing 35a Inlet 35b Discharge Outlet 37 Phase flange 41 Shaft seal device 45 Coolant 46 Lubricant 50A First space 50B Second space 51 Outer casing 51A Partition wall 53 Motor cover 61 Inverter 62 Cable 71 Bearing 72 Bearing 75 Stirring blade

Claims (8)

A motor unit having a metal motor casing and a motor shaft protruding from the bottom surface of the motor casing;
A pump unit having a resin pump impeller connected to the motor shaft, and a resin pump casing for housing the pump impeller;
An outer casing made of resin that surrounds the motor part and forms a housing space for housing the motor part;
A submersible motor pump comprising a cooling liquid sealed in the housing space. A shaft sealing device that is provided between the motor casing and the pump unit and seals the motor shaft;
The housing space has a first space surrounding a side surface of the motor casing, and a second space surrounding the shaft seal device,
The first space and the second space are independent of each other;
The submersible motor pump according to claim 1, wherein the cooling liquid is sealed in the first space. A shaft sealing device that is provided between the motor casing and the pump unit and seals the motor shaft;
The housing space has a first space surrounding a side surface of the motor casing, and a second space surrounding the shaft seal device,
The first space and the second space communicate with each other;
The submersible motor pump according to claim 1, wherein the cooling liquid also functions as a lubricant for the shaft seal device.   The submersible motor pump according to claim 3, wherein the coolant is in contact with a side surface of the motor casing and a top surface of the second space.   5. The submersible motor pump according to claim 3, further comprising a rotary blade provided in the second space and stirring the coolant by rotating together with the motor shaft.   The submersible motor pump according to any one of claims 1 to 5, wherein the motor shaft is made of titanium or a titanium alloy. The motor part has a stator,
The submersible motor pump according to any one of claims 1 to 6, wherein a ratio of a length of the stator in the motor axial direction to a length of the motor casing in the motor axial direction is 0.5 or less. An inverter for controlling the motor unit;
The submersible motor pump according to any one of claims 1 to 7, wherein the inverter controls the motor unit so as to reduce a change in power consumption accompanying a change in discharge amount.

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