JP2019193508A - Canned motor and canned motor pump - Google Patents

Abstract

To prevent the buckling of a can while suppressing deterioration in motor performance when sealing an FRP can with a metal O-ring.SOLUTION: A canned motor includes a rotary shaft, a rotor fixed to the rotary shaft, a stator provided on the outer peripheral side of the rotor, a rotor chamber in which the rotor is housed, a stator chamber in which the stator is housed, a cylindrical can provided between the rotor and the stator and configured to partition the rotor chamber and the stator chamber, and metal O-rings arranged on the outer peripheral surfaces of both ends of the can. The can includes an FRP material. The thickness of both ends of the can where the metal O-rings are disposed is larger than the thickness of the axial center portion of the can.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a canned motor and a canned motor pump.

  In recent years, methane has attracted attention as a clean energy alternative to oil. When methane is transported, liquefied methane (liquefied methane) can be pumped. Since methane is flammable, when liquefied methane is pumped, it is very dangerous if liquefied methane leaks outside. The pump is a device that pumps liquid by rotating an impeller disposed in a pump casing. A pump having a motor outside the pump casing includes a shaft seal device such as a mechanical seal or a gland packing in order to seal a gap between the rotary shaft and the pump casing. However, when the pump is operated for a long period of time, the shaft seal device deteriorates, and as a result, liquefied methane may leak outside through a gap between the rotating shaft and the pump casing. Since the canned motor pump in which the motor and the pump are integrally formed does not require such a shaft seal device, it may become a mainstream in the future as a pump for transporting liquefied methane.

  As a canned motor constituting such a canned motor pump, for example, the motors disclosed in Patent Document 1 and Patent Document 2 are known.

Japanese Utility Model Publication No. 58-46250 JP 2012-213272 A

  Since the boiling point of liquefied methane is as low as −161.5 ° C., a special material and a special motor structure are required for the parts constituting the canned motor. Specifically, for example, when the can is made of metal, the can is cooled by liquefied methane, so that the electrical resistance of the can is reduced. As a result, a large eddy current flows through the metal can, resulting in a decrease in motor performance and a large can loss, which may cause boiling of liquefied methane present in the vicinity of the can. Further, when the canned motor is configured to circulate the pump discharge liquid inside the motor, a high pressure is applied to the inner surface of the can by the discharge liquid. For this reason, it is desirable that the material of the can is FRP.

  The shape of the can is preferably a cylindrical shape so that it can withstand high pressure. Further, it is desirable that the thickness of the can between the stator and the rotor, that is, the portion inserted into the air gap, be as thin as possible in order to maintain the motor performance. Furthermore, since a rubber O-ring cannot be used at a low temperature of −161.5 ° C. or lower, it is necessary to use a metal O-ring to seal both ends of the can.

  However, when the metal O-ring is disposed on the outer peripheral surface of the can and compressed, a large stress is applied to the can and the can may be cylindrically buckled. In addition, the canned motor disclosed in Patent Document 1 and Patent Document 2 has a structure that must be mounted in the groove of the bracket while bending the O-ring, and the metal O-ring is used in such a structure. I can't. For this reason, in the canned motors of Patent Document 1 and Patent Document 2, it is assumed that a rubber O-ring is used.

  The present invention has been made in view of the above problems, and one of its purposes is to prevent can buckling while suppressing deterioration in motor performance when sealing an FRP can with a metal O-ring. It is to be.

  According to one aspect of the present invention, a canned motor is provided. A rotating shaft; a rotor fixed to the rotating shaft; a stator provided on an outer peripheral side of the rotor; a rotor chamber in which the rotor is accommodated; a stator chamber in which the stator is accommodated; the rotor; A cylindrical can provided between the stator and the rotor chamber and the stator chamber; and metal O-rings disposed on outer peripheral surfaces of both ends of the can. . The can includes FRP material. In the can, the thickness of the both end portions where the metal O-ring is disposed is larger than the thickness of the central portion in the axial direction.

  According to another aspect of the present invention, a canned motor pump is provided. The canned motor pump includes the canned motor and an impeller fixed to the rotating shaft.

It is sectional drawing which shows the canned motor pump provided with the canned motor which concerns on this embodiment.

  Embodiments of the present invention will be described below with reference to the drawings. In the drawings described below, the same or corresponding components are denoted by the same reference numerals, and redundant description is omitted. In the present embodiment, the “axial direction” means the axial direction of the rotating shaft shown in FIG.

  FIG. 1 is a cross-sectional view showing a canned motor pump including a canned motor according to the present embodiment. In addition, the part except the impeller 40 and the pump casing 12 which are mentioned later from the canned motor pump 10 corresponds to the canned motor according to the present embodiment.

  As shown in FIG. 1, the canned motor pump 10 includes a pump casing 12, a load side bearing bracket 14, a load side plate 16 (corresponding to an example of a stator side plate), a frame 17, and an anti-load side plate 18 ( Equivalent to an example of a stator side plate) and an anti-load side bracket 20.

  The pump casing 12 includes a liquid suction port 12a and a liquid discharge port 12b. An impeller 40 is disposed inside the pump casing 12. A load-side bearing bracket 14 is attached to the opening on the high-pressure side (anti-load side) of the pump casing 12. A metal O-ring 22 is disposed between the load-side bearing bracket 14 and the pump casing 12. The metal O-ring 22 is crushed in the axial direction by the pump casing 12 and the load side bearing bracket 14 to seal between the load side bearing bracket 14 and the pump casing 12.

  The frame 17 is a substantially cylindrical metal member, and both ends thereof are welded to the load side plate 16 and the anti-load side plate 18 respectively. The load side bearing bracket 14 (corresponding to an example of a bearing bracket) is attached to the load side plate 16 by a fastening member such as a bolt, and defines an axial end portion on the load side of the rotor chamber described later. The anti-load side bracket 20 (corresponding to an example of a bearing bracket) is attached to the anti-load side plate 18 by a fastening member such as a bolt and defines an axial end portion on the anti-load side of the rotor chamber described later.

  One end of the rotating shaft 23 is inserted into the approximate center of the load side bearing bracket 14. An impeller 40 is fixed to one end of the rotating shaft 23 by a fastener 24. In addition, a thrust plate 30a and a thrust plate 30b supported in the axial direction by a bearing 26 and a bearing 28, which will be described later, are attached to the rotating shaft 23. A bearing 26 is provided between the load side bearing bracket 14 and the rotary shaft 23. The bearing 26 supports the outer peripheral surface of the rotating shaft 23 on the inner peripheral surface thereof. The bearing 26 supports the thrust plate 30a attached to the rotary shaft 23 in the axial direction.

  The anti-load side bracket 20 has a cylindrical portion 27 extending in the axial direction. A bearing 28 is provided between the cylindrical portion 27 and the rotating shaft 23. The bearing 28 supports the outer peripheral surface of the rotating shaft 23 on the inner peripheral surface thereof. The bearing 28 supports the thrust plate 30b attached to the rotating shaft 23 in the axial direction. The bearing 26 and the bearing 28 limit the movement of the rotating shaft 23 in the axial direction, and allow the rotating shaft 23 to rotate in the circumferential direction. The bearing 26 and the bearing 28 may be made of a material containing carbon, for example.

  The canned motor pump 10 further includes a rotor 32, a stator 34, a can 36, a rotor chamber 42, and a stator chamber 44. The rotor chamber 42 is a space in which the rotor 32 is accommodated. The stator chamber 44 is a space in which the stator 34 is accommodated. The rotor 32 is positioned between the thrust plate 30 a and the thrust plate 30 b of the rotating shaft 23 and is fixed to the rotating shaft 23. The stator 34 is disposed so as to face the outer peripheral side of the rotor 32. The can 36 has a substantially cylindrical shape as a whole, and is disposed between the rotor 32 and the stator 34. The can 36 has a load-side end 36a and an anti-load-side end 36b. The load side end 36 a contacts the load side bearing bracket 14 and the load side plate 16, and the anti-load side end 36 b contacts the anti-load side bracket 20 and the anti-load side plate 18. Thus, the can 36 partitions the rotor chamber 42 and the stator chamber 44. Specifically, the rotor chamber 42 is defined by the can 36, the load side bearing bracket 14, and the anti-load side bracket 20. The stator chamber 44 is defined by the can 36, the load side plate 16, the frame 17, and the anti-load side plate 18.

  The load-side bearing bracket 14 has a flow hole 14 a that allows the inside of the pump casing 12 to communicate with the rotor chamber 42. Thereby, the liquid pressurized by the impeller 40 flows into the rotor chamber 42 through the circulation hole 14a. The rotary shaft 23 has a shaft through hole 23 a that allows the rotor chamber 42 to communicate with the vicinity of the suction port 12 a of the pump casing 12. The shaft through hole 23 a is a through hole extending in the axial direction from one end surface of the rotating shaft 23 toward the other end surface. The liquid that has flowed into the rotor chamber 42 passes between the rotor 32 and the can 36 through the hole 27a formed in the tubular portion 27 of the anti-load side bracket 20 and reaches the shaft through hole 23a. The liquid that has reached the shaft passage hole 23a flows out into the pump casing 12 toward the low-pressure suction port 12a. Thereby, the liquid pressurized by the impeller 40 circulates between the rotor chamber 42 and the inside of the pump casing 12, the rotor 32 is cooled, and the bearing 26 and the bearing 28 are lubricated.

In order to transport a low-temperature liquid such as liquefied methane in the canned motor pump 10 of the present embodiment, the can 36 is formed including an FRP (fiber reinforced plastic) material. Accordingly, since the can 36 is not formed of metal, the generation of eddy current in the can is suppressed, and the motor performance can be prevented from being lowered and the occurrence of can loss can be prevented. In particular, the can 36 is preferably formed including a GFRP (glass fiber reinforced plastic) material. The linear expansion coefficient of the GFRP material is about 7 to 10 × 10 ⁻⁶ , and the linear expansion coefficient of the metal constituting the canned motor pump 10 is, for example, about 10 to 14 × 10 ⁻⁶ . For this reason, the GFRP material has a linear expansion coefficient that is relatively close to the linear expansion coefficient of the metal constituting the canned motor pump 10. Therefore, the difference in thermal expansion and thermal contraction between the can 36 and the metal material constituting the canned motor pump 10 can be suppressed.

  Further, the canned motor pump 10 of the present embodiment transports a low-temperature liquid such as liquefied methane, so that a metal O-ring 46 is provided between the end 36a of the can 36 and the load side plate 16 and the load side bearing bracket 14. It is sealed. Similarly, the end 36 b of the can 36 and the anti-load side plate 18 and the anti-load side bracket 20 are sealed with a metal O-ring 48. As illustrated, the metal O-ring 46 and the metal O-ring 48 are disposed on the outer peripheral surfaces of the end portion 36a and the end portion 36b of the can 36, respectively.

  In order to seal between the can 36 and the load side plate 16 with the metal O-ring 46, it is necessary to crush the metal O-ring 46. Similarly, in order to seal between the can 36 and the anti-load side plate 18 with the metal O-ring 48, the metal O-ring 48 needs to be crushed. In this case, a large stress is applied to the can 36, and the can 36 may be cylindrically buckled. In order to prevent the cylindrical buckling of the can 36, it is conceivable to increase the thickness of the can 36 as a whole. However, it is desirable that the thickness of the can 36 between the stator 34 and the rotor 32, that is, the portion inserted into the air gap, be as thin as possible in order to maintain the motor performance.

  Therefore, in the present embodiment, as shown in the figure, the thickness of the can 36 between the stator 34 and the rotor 32 is made thinner than the thickness of the end portion 36a and the end portion 36b of the can 36. In other words, the thickness of the end portion 36 a and the end portion 36 b of the can 36 in which the metal O-ring 46 and the metal O-ring 48 are disposed is larger than the thickness of the central portion in the axial direction of the can 36. Thereby, cylindrical buckling of the can 36 by the metal O-ring 46 and the metal O-ring 48 can be prevented while maintaining the motor performance.

  When the end 36a and the end 36b of the can 36 are thicker than the central portion in the axial direction, the end 36a and the end 36b cannot be unconditionally thickened. Specifically, it is necessary to design the can 36 so that the can 36 can be inserted into the stator 34 and the rotor 32 can be inserted into the can 36.

  Therefore, in the present embodiment, the inner diameter of the can 36 at the load-side end 36a is larger than the maximum outer diameter of the rotor 32, and the outer diameter of the can 36 at the end 36a is larger than the minimum inner diameter of the stator. It is formed. Thereby, the rotor 32 can be inserted from the load-side end 36a of the can 36, and the thickness of the end 36a can be ensured.

  In the present embodiment, the inner diameter of the can 36 at the end portion 36 b on the opposite load side is smaller than the maximum outer diameter of the rotor 32, and the outer diameter of the can 36 at the end portion 36 b is smaller than the minimum inner diameter of the stator 34. Formed as follows. Thereby, the end part 36b of the can 36 on the non-load side can be inserted into the stator 34, and the thickness of the end part 36b can be secured.

  In the present embodiment, the inner diameter of the end portion 36 a is the same as the inner diameter of the central portion of the can 36. Therefore, the end portion 36a forms a stepped portion 50 with respect to the central portion of the can 36 so as to protrude outward in the radial direction as shown in the drawing. As a result, when the end portion 36 b of the can 36 is inserted into the stator 34, the stepped portion 50 comes into contact with the stepped portion of the load side plate 16, and the movement of the can 36 in the axial direction is limited. As a result, the can 36 can be easily fixed in the axial direction, and the can motor pump 10 can be easily assembled and disassembled.

As illustrated, the metal O-ring 46 is in contact with the outer peripheral surface of the can 36, the surface 16 a of the load side plate 16, and the surface 14 b of the load side bearing bracket 14. The outer peripheral surface of the can 36 and the surface 14b of the load side bearing bracket 14 are disposed so as to be orthogonal to each other. Further, the surface 16 a of the load side plate 16 is disposed so as to be inclined at a predetermined angle with respect to the outer peripheral surface of the can 36 and the surface 14 b of the load side bearing bracket 14. In the present embodiment, the load side plate 16
The surface 16a is arranged so as to be inclined at an angle of about 45 ° with respect to the outer peripheral surface of the can 36 and the surface 14b of the load side bearing bracket 14, respectively. The can 36, the load side plate 16, and the load side bearing bracket 14 are compressed by pressing the metal O-ring 46 against each other, whereby the rotor chamber 42 is sealed. Thereby, the metal O-ring 46 seals between the outer peripheral surface of the can 36 and the load side plate 16 and between the load side plate 16 and the load side bearing bracket 14.

  Further, the metal O-ring 48 is in contact with the outer peripheral surface of the can 36, the surface 18 a of the anti-load side plate 18, and the surface 20 b of the anti-load side bracket 20. The outer peripheral surface of the can 36 and the surface 18a of the anti-load side plate 18 are disposed so as to be orthogonal to each other. Further, the surface 20b of the anti-load side bracket 20 is disposed so as to be inclined at a predetermined angle with respect to the outer peripheral surface of the can 36 and the surface 18a of the anti-load side plate 18. In the present embodiment, the surface 20b of the anti-load side bracket 20 is disposed so as to be inclined at an angle of about 45 ° with respect to the outer peripheral surface of the can 36 and the surface 18a of the anti-load side plate 18. The can 36, the anti-load side plate 18, and the anti-load side bracket 20 are compressed by pressing the metal O-ring 48 against each other, whereby the rotor chamber 42 is sealed. Specifically, the metal O-ring 48 seals between the outer peripheral surface of the can 36 and the anti-load side plate 18 and between the anti-load side plate 18 and the load side bearing bracket 14.

  In order to compress the metal O-ring 46 and the metal O-ring 48, first, the end portion 36 b of the can 36 is inserted into the stator 34, and the stepped portion 50 of the can 36 is brought into contact with the stepped portion of the load side plate 16. Make contact. Next, the rotor 32 is inserted into the inner periphery of the can 36 from the end 36 a side to the end 36 b side of the can 36. Subsequently, the metal O-ring 46 is disposed on the outer periphery of the end portion 36 a of the can 36. Thereafter, the load side bearing bracket 14 is pressed against the load side plate 16. As a result, the metal O-ring 46 is compressed by the load side plate 16, the can 36 and the load side bearing bracket 14.

  Subsequently, a metal O-ring 48 is disposed on the outer periphery of the end portion 36 b of the can 36. The anti-load side bracket 20 is attached to the anti-load side plate 18. By attaching the anti-load side bracket 20 to the anti-load side plate 18, the surface 20 b of the anti-load side bracket 20 presses the metal O-ring 48 against the can 36 and the anti-load side plate 18. As a result, the metal O-ring 48 is compressed by the anti-load side plate 18, the can 36, and the anti-load side bracket 20.

  As described above, the metal O-ring 46 and the metal O-ring 48 are pressed and compressed by the three surfaces. When the metal O-ring 46 and the metal O-ring 48 are pressed against the can 36 and are slid in the axial direction with respect to the outer peripheral surface of the can 36, the FRP can 36 is damaged and causes liquid leakage. There is a fear. In the present embodiment, the metal O-ring 46 and the metal O-ring 48 are arranged on the outer peripheral surface of the can 36 without applying force, and then the metal O-ring 46 and the metal O-ring 48 are pressed by three surfaces and compressed. Yes. For this reason, in this embodiment, it is possible to prevent the can 36 from being damaged when the metal O-ring 46 and the metal O-ring 48 are attached.

  In the present embodiment, the outer peripheral surface of the can 36 and the surface 14b of the load side bearing bracket 14 are arranged so as to be orthogonal to each other, but the present invention is not limited to this. If the outer peripheral surface of the can 36, the surface 14b of the load side bearing bracket 14 and the surface 16a of the load side plate 16 can press the metal O-ring 46 against each other, the outer peripheral surface of the can 36 and the load side The angle formed by the surface 14b of the bearing bracket 14 is arbitrary. Similarly, the angle formed by the outer peripheral surface of the can 36 and the surface 18a of the anti-load side plate 18 is also arbitrary.

As mentioned above, although embodiment of this invention was described, embodiment of the invention mentioned above is for making an understanding of this invention easy, and does not limit this invention. The present invention can be changed and improved without departing from the gist thereof, and the present invention includes the equivalents thereof. In addition, any combination or omission of each component described in the claims and the specification is possible within a range in which at least a part of the above-described problems can be solved or a range in which at least a part of the effect is achieved. is there.

Some of the forms disclosed in this specification will be described below.
According to the first aspect, a canned motor is provided. A rotating shaft; a rotor fixed to the rotating shaft; a stator provided on an outer peripheral side of the rotor; a rotor chamber in which the rotor is accommodated; a stator chamber in which the stator is accommodated; the rotor; A cylindrical can provided between the stator and the rotor chamber and the stator chamber; and metal O-rings disposed on outer peripheral surfaces of both ends of the can. . The can includes FRP material. In the can, the thickness of the both ends where the metal O-ring is disposed is larger than the thickness of the central portion in the axial direction.

  According to the 1st form, the thickness of the both ends of the can in which the metal O-ring is arrange | positioned is thicker than an axial direction center part. Thereby, cylindrical buckling of the can by a metal O-ring can be prevented, maintaining motor performance.

  According to the second aspect, the canned motor of the first aspect includes a stator side plate that defines an axial end portion of the stator chamber and a bearing bracket that defines an axial end portion of the rotor chamber. The metal O-ring contacts the can, the stator side plate, and the bearing bracket, and the can, the stator side plate, and the bearing bracket compress the metal O-ring, thereby The chamber is sealed.

  According to the 2nd form, a metal O-ring is compressed by three members, a can, a stator side plate, and a bearing bracket. If the metal O-ring is pressed against the can in the axial direction with respect to the outer peripheral surface of the can, the FRP can may be damaged to cause liquid leakage. According to the second embodiment, since the metal O-ring can be pressed against the outer peripheral surface of the can by the stator side plate and the bearing bracket with the metal O-ring arranged on the can, the can is prevented from being damaged when the metal O-ring is attached. Can do.

  According to a third aspect, in the canned motor of the first aspect or the second aspect, the can has a first end and a second end opposite to the first end, and the first The one end portion has an inner diameter larger than the maximum outer diameter of the rotor, the outer diameter is larger than the minimum inner diameter of the stator, and the second end portion has an inner diameter smaller than the maximum outer diameter of the rotor. The outer diameter is smaller than the minimum inner diameter of the stator.

  According to the 3rd form, a rotor can be inserted from the 1st end part of can 36, and the thickness of the 1st end part can be secured. Further, the second end portion of the can can be inserted into the stator, and the thickness of the second end portion can be ensured.

  According to a 4th form, in the can motor of any one of the 1st form to the 3rd form, the can contains a GFRP material.

  According to the 4th form, the thermal expansion difference and thermal contraction difference between a can and the metal material which comprises a canned motor can be suppressed.

According to the fifth embodiment, a canned motor pump is provided. This canned motor pump has the canned motor of the 1st form to the 3rd form, and the impeller fixed to the said rotating shaft.

DESCRIPTION OF SYMBOLS 10 ... Canned motor pump 12 ... Pump casing 14 ... Load side bearing bracket 16 ... Load side plate 18 ... Anti load side plate 20 ... Anti load side bracket 22 ... Rotating shaft 32 ... Rotor 34 ... Stator 36 ... Can 36a ... End part 36b ... End 40 ... Impeller 42 ... Rotor chamber 44 ... Stator chamber 46 ... Metal O-ring 48 ... Metal O-ring

Claims (5)

A rotation axis;
A rotor fixed to the rotating shaft;
A stator provided on the outer peripheral side of the rotor;
A rotor chamber in which the rotor is accommodated;
A stator chamber in which the stator is accommodated;
A cylindrical can provided between the rotor and the stator and configured to partition the rotor chamber and the stator chamber;
A metal O-ring disposed on the outer peripheral surface of both ends of the can,
The can includes FRP material;
The can is a canned motor in which the thickness of the both ends where the metal O-ring is disposed is larger than the thickness of the central portion in the axial direction. The canned motor according to claim 1,
A stator side plate defining an axial end of the stator chamber;
A bearing bracket defining an axial end of the rotor chamber;
The metal O-ring contacts the can, the stator side plate, and the bearing bracket,
The can motor, wherein the can, the stator side plate, and the bearing bracket compress the metal O-ring to seal the rotor chamber. In the canned motor according to claim 1 or 2,
The can has a first end and a second end opposite to the first end,
The first end portion has an inner diameter larger than the maximum outer diameter of the rotor, and the outer diameter is larger than the minimum inner diameter of the stator.
The second end portion is a canned motor having an inner diameter smaller than a maximum outer diameter of the rotor and an outer diameter smaller than a minimum inner diameter of the stator. In the canned motor according to any one of claims 1 to 3,
The can is a canned motor including a GFRP material. A canned motor according to any one of claims 1 to 4,
A canned motor pump having an impeller fixed to the rotating shaft.

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