JP4187606B2 - Electric motor - Google Patents

Description

  The present invention relates to an electric motor used at low speed and large torque.

  In general, the temperature of an electric motor rises due to heat generated due to copper loss, iron loss, mechanical loss, etc. that cannot be avoided. Therefore, the inside of the electric motor is cooled.

  As such, for example, in an electric motor in which a rotor and a stator arranged outside the rotor are accommodated in a casing, two fans are respectively attached to both end portions sandwiching the rotor of the rotary shaft, and the rotor An electric motor has been proposed in which an inner air circulation path is provided in the casing and an outer air circulation path is provided in the casing (see, for example, Patent Document 1).

  In this electric motor, when the rotation shaft rotates at a predetermined rotation speed, the two fans also rotate at the same rotation speed. At this time, one of the fans sucks the air inside the electric motor and pressurizes it to flow into the inner air circulation path. The inflowing air flows in the inner air circulation path and absorbs heat from the rotor. This air is sucked into the other fan. Thereafter, the other fan pressurizes and discharges this air. Thereafter, the discharged air flows into the outer air circulation path, and is cooled by exchanging heat with the air outside the casing. This air is then sucked into one of the fans again. As described above, heat generation of the stator and the rotor is suppressed.

  However, in the case of an electric motor that rotates at a low speed, the rotating shaft rotates at a low speed. Therefore, even if a fan is attached to the rotating shaft as described above, it is necessary for the fan to effectively cool the rotor and the stator. I cannot flow air. For this reason, the temperature of the rotor and the stator increases, and the rated capacity of the motor may decrease due to the temperature limit of the insulator.

  In order to cope with this, an electric motor that cools the inside of the electric motor by providing a fan driven independently of the electric motor has been proposed (for example, see Patent Document 2).

  This motor is in contact with each rotor, a main rotor that is rotatably mounted around the shaft inside the stator, a sub-rotor with a cooling fan that is rotatably mounted on the shaft of the main rotor, and the rotor. And a brush for energizing the windings of each rotor.

However, since the sub-rotor is disposed inside the stator in this electric motor, when the fan is attached, it is necessary to attach the fan to the axial end of the rotor so as not to interfere with the stator. Therefore, there exists a problem that an electric motor becomes long and becomes large in the axial direction of a rotating shaft. In addition, since this electric motor has a brush, the maintainability is deteriorated, and further, there is a problem that the electric motor is enlarged because it is necessary to extend a commutator that the brush contacts to one end in the axial direction of each rotor.
Japanese Patent Laid-Open No. 10-285875 (FIG. 1) Japanese Unexamined Patent Publication No. 3-103051 (FIG. 1)

  The present invention has been made to solve the above problems, and an object thereof is to provide an electric motor that can be made compact without reducing the rated capacity.

The apparatus of the present invention includes a casing, an output shaft supported at both ends of the casing so as to be rotatable, a first rotor provided coaxially with the output shaft, and an outer side of the first rotor. a main motor having a first stator which is arranged fixed to the inner surface of the casing, respectively provided at both ends of the output shaft concentric with the second stator and second stator attached to the inner surface of the casing Two sub-motors having a second rotor disposed so as to surround each other, a cooling fan disposed on the outer periphery of each second rotor, the outer periphery of the first stator, and the casing A first cooling passage for circulating fluid discharged from a gap formed between the first rotor and the first stator between the inner periphery and an outer periphery of the first stator A second cooling passage through which a coolant for cooling the first stator flows. And a cooling member, the two sub-motors are arranged so as to surround the outer periphery of the output shaft, the gap the cooling fan on one side is formed between the first rotor and the first stator The cooling fan on the other side is configured to suck the fluid flowing out from the gap and discharges it toward the first cooling path, and the number of poles of the sub motor is the number of poles of the main motor. are those set smaller than the number.

  According to this configuration, since the main motor for obtaining the output and the sub motor for cooling the main motor are separated, the sub motor with the cooling fan attached while keeping the rotation speed of the output shaft low. Can be rotated at a high speed. As a result, the cooling fan can exhaust air necessary for effectively cooling the first rotor and the first stator. Thereby, the temperature rise by the copper loss, iron loss, etc. of a 1st rotor and a 1st stator can be suppressed, and the fall of the rated capacity of an electric motor can be prevented.

  Further, since the second rotor is disposed so as to surround the second stator and the cooling fan is attached to the outer peripheral portion of the second rotor, the auxiliary motor does not become longer in the axial direction as in the prior art. Thereby, a submotor can be made compact.

Furthermore, in the present invention, the sub motor is rotated at a higher speed than the main motor by changing the number of poles of the main motor and the sub motor instead of changing the frequency of the power source, so that a special power source such as an inverter or a converter is not required. It becomes. As a result, the entire apparatus can be simplified and can be made compact.
Further, according to the present invention, heat received from the first rotor and the first stator when the fluid flows in the first cooling passage can be radiated to the outside through the casing. That is, the first cooling passage is for cooling the fluid after cooling the first rotor and the like. Thereby, it becomes possible to keep the temperature inside the electric motor at a predetermined temperature. As a result, the temperature rise of the electric motor can be prevented.
Furthermore, according to the present invention, since the fluid cooled in the first cooling passage can be efficiently flowed into the gap, the cooling effect of the first rotor and the first stator is improved. Thereby, the temperature rise by the copper loss, iron loss, etc. of a 1st rotor and a 1st stator can be suppressed, and the fall of the rated capacity of an electric motor can be prevented.
Furthermore, according to the present invention, the first stator is efficiently cooled. Further, when the first cooling passage is provided outside the first stator as described above, the fluid flowing through the first cooling passage can be cooled by the refrigerant flowing through the second cooling passage. As a result, the temperature inside the motor can be maintained at a predetermined temperature, and a reduction in the rated capacity of the motor can be prevented. In addition, water, seawater, etc. are used as a refrigerant | coolant.

The sub-motor is accommodated in a space formed between the axial end of the first rotor and the inner surface of the casing facing the end, at least a part of which is inside the first stator. It is desirable to be configured to be located in

  In the case of a low-speed, large-torque motor, the first rotor of the main motor has a large diameter, and both ends of the first stator coil facing the both ends of the casing are separated from both ends of the first rotor in the axial direction. Each projectes outward. As a result, spaces surrounded by the projecting portion of the first stator, the axial end surface of the first rotor, and the casing inner surface facing this are inevitably formed. In the present invention, since the auxiliary motor is accommodated in this space, the entire apparatus can be made compact.

  Permanent magnets may be disposed on the outer periphery of the first rotor, or permanent magnets may be disposed on the inner periphery of the second rotor.

  As described above, by using a permanent magnet, heat generation can be reduced compared to the case of using an electromagnet. At the same time, the main motor or the sub motor can be made smaller. Thereby, the whole apparatus can be made compact.

  The sub motor may be connected to the same power source as the main motor. This makes it possible to minimize the complexity of wiring and control of the main motor and the sub motor. As a result, the entire apparatus is simplified and compact.

  According to the present invention, the entire apparatus can be made compact without reducing the rated capacity of the electric motor.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a longitudinal sectional view of an electric motor according to an embodiment of the present invention. FIG. 2A is a partial perspective view of the first cooling fan. FIG. 2B is a partial perspective view of the second cooling fan.

  As shown in FIG. 1, the electric motor 1 includes a casing 2, an output shaft 3 rotatably attached to the casing 2, a main motor 4 that drives the output shaft 3, and the main motor 4 for cooling the main motor 4. The cooling fan 5 and the auxiliary electric motor 6 that drives the cooling fan 5 are provided.

  The casing 2 is formed in a substantially cylindrical shape. At the center of both end portions of the casing 2 in the axial direction, holes 2a penetrating in the axial direction are respectively provided, and bearings 7a and 7b are fitted into the respective holes 2a. The output shaft 3 is fitted in each of the bearings 7a and 7b. Thereby, the output shaft 3 is rotatably supported by the bearings 7a and 7b.

  The output end of the output shaft 3 passes through a bearing 7 a on one side (left side in FIG. 1) in the axial direction of the casing 2 and protrudes outside the casing 2. A driven shaft (not shown) of a low-speed large torque propulsion device for ships or the like is connected to the output end of the output shaft 3.

  A first large-diameter portion 3a having a larger diameter than a portion fitted into the bearings 7a and 7b of the output shaft 3 is provided at the central portion of the output shaft 3 in the axial direction. A first rotor 8 of a main motor 4 described later is coaxially attached to the first large diameter portion 3a.

  On the side opposite to the output end side of the first large diameter portion 3a (on the right side in FIG. 1), from the first large diameter portion 3a for axial positioning of the first rotor 8 of the main motor 4 described later. A second large diameter portion 3b having a large diameter is provided.

  The main motor 4 includes a first rotor 8 that is coaxially attached to the first large diameter portion 3 a, and a first stator 9 that is disposed outside the first rotor 8.

  The first rotor 8 includes a plurality of disk-shaped rotor disks 8a having a through hole for inserting the first large diameter portion 3a in the center. The first rotor 8 is formed so that these rotor disks 8a are overlapped in the axial direction of the first large diameter portion 3a. Thereby, the whole 1st rotor 8 is formed in a cylindrical shape.

  A plurality of plate-shaped first permanent magnets 8b curved along the outer peripheral surface are attached to the outer peripheral surface of each rotor disk 8a. By using a permanent magnet in this way, heat generation can be reduced compared to the case of using an electromagnet. At the same time, the first rotor 8 can be made smaller. The first permanent magnets 8 b are arranged in the circumferential direction of the first rotor 8 in a number corresponding to the number of poles of the main motor 4.

  The first stator 9 includes an annular first stator iron core 9a and a plurality of first armature coils 9b wound around the teeth of the first stator iron core 9a. It is formed in a shape. The first stator 9 is fixed to the inner surface of the casing 2.

  As shown in FIG. 1, the end portion (coil end) of the first armature coil 9 b projects from both axial sides of the first stator core 9 a toward both axial ends of the casing 2. This overhanging portion 9c corresponds to a folded portion of the first armature coil 9b. As a result, a space S that is unavoidable in structure is formed inside the protruding portion 9c. The space S is formed between the axial end surface of the first rotor 8 and the inner surface of the casing facing the end surface, and a later-described sub motor 6 is accommodated in the space S. As a result, the electric motor 1 can be prevented from becoming extremely long in the axial direction of the output shaft 3.

  A cylindrical cooling member 10 for cooling the first stator 9 and the like is attached to the outer peripheral surface of the first stator 9 so as to surround the first stator 9. Inside the cooling member 10, a plurality of refrigerant passages 10 a having a rectangular cross section through which a refrigerant such as water or seawater flows are arranged in parallel in the axial direction. The refrigerant passage 10 a is formed along the circumferential direction of the cooling member 10. This refrigerant passage 10a constitutes a second cooling passage.

  The shape of the cooling member 10 and the refrigerant passage 10a, the number of flow paths, and the like are appropriately set according to the amount of heat exchange with the first stator 9 and the like. Here, the refrigerant passage 10a is composed of a plurality of flow paths, but may be a single flow path. In that case, it is preferable that the refrigerant passage 10 a is disposed in a spiral shape in the axial direction inside the cooling member 10.

  The auxiliary electric motor 6 includes a second rotor 11 and a second stator 12 corresponding to the second rotor 11. Two sub-motors 6 are disposed, one of which is disposed between the bearing 7a of the output shaft 3 and the first large-diameter portion 3a, and the other is the bearing 7b and the second large-diameter portion 3b. It is arranged between. Each sub-motor 6 is supported by cylindrical support portions 2b that project from the inner surfaces of both ends of the casing 2 so as to surround the output shaft 3 coaxially. More specific description will be given below.

  The second rotor 11 covers the outer cylinder part 11a, the inner cylinder part 11b concentrically disposed inside the outer cylinder 11a, and the peripheral edges on the same side of the outer cylinder part 11a and the inner cylinder part 11b. The bottom part 11c formed in this. That is, as shown in the drawing, the second rotor 11 is formed in a U shape in a longitudinal sectional view passing through the axis. In the second rotor 11, the outer surface of the bottom portion 11 c faces the axial end of the first rotor 8, and the open portion (opposite side of the bottom portion 11 c) faces the inner surface of the axial end of the casing 2. Has been placed.

  A bearing 14 for rotatably supporting the second rotor 11 on the support portion 2b is fitted in the inner peripheral surface of the inner cylinder portion 11b. The bearing 14 is externally fitted to an inner peripheral portion of a concave portion 2c formed in a cylindrical shape on the end surface of the support portion 2b on the main motor 4 side. As a result, the second rotor 11 can be rotatably supported by the support portion 2b.

  A plurality of plate-like second permanent magnets 13 that are curved along the inner peripheral surface are attached to the inner peripheral surface of the outer cylinder portion 11a. The number of the second permanent magnets 13 corresponding to the number of poles of the auxiliary motor 6 is arranged in the circumferential direction of the second rotor 11. As a result, the heat generation of the second rotor 11 can be reduced and the second rotor 11 can be reduced in the same manner as described above for the first rotor 8.

  Here, the number of poles of the sub motor 6 is set to be smaller than the number of poles of the main motor 4. For example, the number of poles of the main motor 4 is set to 48 (rotational speed at 60 Hz: equivalent to 150 rpm), and the number of poles of the auxiliary motor 6 is set to 2 or 4 (rotational speed at 60 Hz: equivalent to 3600 rpm or 1800 rpm). can do. Thereby, the sub motor 6 can be rotated at a higher speed than the main motor 4. As a result, the cooling fan 5 described later can be rotated at high speed, and the main motor 4 can be sufficiently cooled. Details will be described later.

  The second stator 12 includes an annular second stator iron core 12a and a plurality of second armature coils 12b wound around the teeth of the second stator iron core 12a, and the whole is substantially cylindrical. It is formed in a shape. The second stator 12 is fixed on the outer peripheral surface of the support portion 2b.

  The air in the casing 2 is sucked into the outer peripheral portion of the second rotor 11 on the output end side (the left side in FIG. 1) of the output shaft 3 among the second rotors 11 and the first rotor 8 and the first rotor 1. The 1st cooling fan 16 for making it flow in in the clearance gap 15 formed between the stators 9 is attached. A second cooling fan 17 for sucking the air flowing into the gap 15 is attached to the outer peripheral portion of the second rotor 11 on the side opposite to the output end side of the output shaft 3 (right side in FIG. 1). ing.

  Here, the first cooling fan 16 and the second cooling fan 17 are provided. However, air necessary for cooling the first rotor 8 and the first stator 9 is allowed to flow in the gap 15. If it is possible, only one of them may be provided. That is, only the first cooling fan 16 that allows air to flow into the gap 15 may be provided, or only the second cooling fan 17 that sucks air from the gap 15 may be provided.

  The 1st cooling fan 16 is located inside the overhang | projection part 9c of the output end side (left side of FIG. 1) of the 1st armature coil 9b. The first cooling fan 16 is configured such that the air discharged from the first cooling fan 16 goes to the gap 15 between the first rotor 8 and the first stator 9.

  Specifically, the first cooling fan 16 includes a plate-like first blade 18 and a first rotor disk 19 that supports the first blade 18. As shown in FIGS. 1 and 2 (a), the first rotor disk 19 has an annular shape, and an inner peripheral portion 19a is bent at a substantially right angle on one side, and an outer peripheral portion 19b is the same. Inclined radially outward and bent. That is, the first support member 19 has a U-shaped cross section when viewed in the circumferential direction. The first rotor disk 19 is arranged so that the end of the outer peripheral portion 19 b faces the gap 15. An inner peripheral portion 19 a of the first rotor disk 19 is fitted on the outer peripheral surface of the outer peripheral portion of the second rotor 11. As a result, the first rotor disk 19 rotates together with the second rotor 11.

  Further, the first blades 18 are equally arranged in the circumferential direction on the outer peripheral portion 19 b of the first rotor disk 19 and are erected in a radial manner. An annular first shroud 18 a is attached to the radially outer end of each first blade 18 so as to cover the space between each first blade 18. The first shroud 18a is arranged substantially parallel to the outer peripheral portion 19b. Thereby, the 1st flow path 16a is formed between each 1st blade | wing 18. Since the first flow path 16a is formed so as to be sandwiched between the outer peripheral portion 19b and the first shroud 18a, the same direction as the outer peripheral portion 19b and the first shroud 18a (radially outward toward the gap 15). It is inclined to. As a result, the air discharged from the first flow path 16a flows toward the gap 15 as indicated by an arrow R1 in FIGS. 1 and 2A.

  The 2nd cooling fan 17 is formed so that the outer peripheral part may extend between the overhang | projection part 9c on the opposite side to the output end side of the 1st armature coil 9b, and the inner surface of the casing 2 facing this. Thereby, the air sucked from the gap 15 by the second cooling fan 17 can be easily supplied to the circulation passage 22 described later.

  The second cooling fan 17 includes a plate-like second blade 20 and a second rotor disk 21 that supports the second blade 20. As shown in FIGS. 1 and 2B, the second rotor disk 21 includes a cylindrical portion 21 a formed so as to concentrically surround the second rotor 11 on the side opposite to the output end side of the output shaft 3. And a plate-like body 21b erected in an annular shape on the outer peripheral surface in the middle of the axial direction of the cylindrical portion 21a.

  The second blades 20 are erected on the surface of the outer peripheral portion of the plate-like body 21b on the main motor 4 side, and are equally distributed radially in the circumferential direction. Each second blade 20 is inclined radially outward with respect to the plate-like body 21b in order to reduce resistance when air is sucked. An annular second shroud 20 a is attached to the end of each second blade 20 on the main motor 4 side so as to cover the space between the second blades 20. Thereby, the 2nd flow path 17a is formed between each 2nd blade | wing 20. FIG. Therefore, the second flow path 17a is formed radially in the circumferential direction of the plate-like body 21b. As a result, the air sucked into the second cooling fan 17 flows radially outward in the second flow path 17a as indicated by an arrow R3 in FIGS. 1 and 2B.

  A circulation passage 22 is formed between the outer peripheral surface of the cooling member 10 and the inner peripheral surface of the casing 2 to return the air discharged from the second cooling fan 17 to the first cooling fan 16 side. ing. Thus, the air flowing in the circulation passage 22 is cooled by exchanging heat with the air outside the outer peripheral portion of the casing 2 and the refrigerant in the refrigerant passage 10a through the outer peripheral portion of the casing 2 and the cooling member 10. The circulation passage 22 constitutes a first cooling passage.

  Although not shown, in order to promote the heat exchange, fins or the like are provided on the outer peripheral surface of the cooling member 10 and the inner peripheral surface or the outer peripheral surface of the casing 2, or on the outer peripheral surface of the cooling member 10. It is desirable to meander the circulation passage 22 by protruding a baffle plate or the like. If the first rotor 8 and the first stator 9 generate a small amount of heat, only the circulation passage 22 may be provided without providing the cooling member 10. Thereby, the apparatus structure can be simplified.

  In the electric motor 1 configured as described above, first, the first cooling fan 16 sucks the air in the casing 2 (see arrow R1 in FIG. 1). The first cooling fan 16 pressurizes this air and causes it to flow into the gap 15 formed between the first rotor 8 and the first stator 9. The air that has flowed in flows through the gap 15 toward the second cooling fan 17 (see arrow R2 in FIG. 1). At this time, the air absorbs heat from the first permanent magnet 8 b and the first stator 9. Thereafter, this air is sucked into the second cooling fan 17 (see arrow R3 in FIG. 1), and the second cooling fan 17 pressurizes the air and discharges it to the discharge side space of the second cooling fan 17. Thereafter, the air flows toward the inner peripheral surface of the casing 2 and flows into the circulation passage 22 as indicated by an arrow R4 in FIG. The air flows in the circulation passage 22 toward the first cooling fan 16 side (see arrow R5 in FIG. 1). At this time, when this air is exchanged with the air outside the casing 2 and the refrigerant in the refrigerant passage 10a and discharged from the circulation passage 22, it is cooled to substantially the original temperature. The discharged air flows inward in the radial direction along the end of the casing 2 and is sucked into the first cooling fan 16 again, as indicated by an arrow R6 in FIG.

  As described above, the air in the casing 2 is circulated. As a result, the first rotor 8 and the first stator 9 are cooled and can directly absorb heat generated by copper loss, iron loss, and the like. Thereby, the capacity | capacitance fall by the temperature limitation of the electric motor 1 can be prevented. Furthermore, since the air in the casing 2 is circulated and used, dust and the like can be prevented from being brought into the casing 2 from the outside. Thereby, the performance fall of the electric motor 1 by dust etc. adhering to the 1st permanent magnet 8b can be prevented.

  In the present embodiment, as described above, the number of poles of the sub motor 6 is smaller than the number of poles of the main motor 4, so that the sub motor 6 is rotated at high speed by the main motor 4 without changing the frequency of the power source. Can be made. Therefore, the power sources of the main motor 4 and the sub motor 6 can be made the same. Thereby, the wiring and control of the main motor 4 and the sub motor 6 can be simplified. Of course, the power sources of the main motor 4 and the sub motor 6 may be separate power sources. Thereby, only the sub motor 6 can be driven, and for example, it is possible to cope with an application that requires a large cooling capacity when the main motor 4 such as an elevator is stopped.

  The above-described embodiment is an example, and various modifications can be made without departing from the spirit of the present invention, and the present invention is not limited to the above-described embodiment.

  For example, the present invention is applied to a low speed large torque propulsion device such as a ship.

It is a longitudinal section of the electric motor concerning one embodiment of the present invention. (A) is a partial perspective view of a 1st cooling fan, (b) is a partial perspective view of a 2nd cooling fan.

Explanation of symbols

1 ... Electric motor
2 ... Casing
3 ... Output shaft
4 ... Main motor
5 ... Cooling fan
6 ... Sub-motor
8 ... 1st rotor
8a ... Rotor disc
8b ... 1st permanent magnet
9 ... 1st stator
10a: Refrigerant passage (second cooling passage)
11 ... second rotor
12 ... Second stator
15 ... Gap
22 ... Circulation passage (first cooling passage)

Claims (5)

A casing,
An output shaft that is rotatably supported by the casing at both ends;
A main motor including a first rotor provided coaxially with respect to the output shaft, and a first stator disposed outside the first rotor and fixed to the inner surface of the casing;
Respectively provided at both ends of the output shaft, and two sub motor having a second rotor a second stator and a second stator which is attached to the inner surface of the casing disposed so as to surround concentrically ,
A cooling fan disposed on the outer periphery of each of the second rotors ;
A first for circulating fluid discharged from a gap formed between the first rotor and the first stator between the outer peripheral portion of the first stator and the inner peripheral portion of the casing. A cooling passage,
A cooling member having a second cooling passage for flowing a refrigerant for cooling the first stator on the outer periphery of the first stator ;
The two auxiliary motors are arranged so as to surround the outer periphery of the output shaft,
The cooling fan on one side is formed so as to flow a fluid through a gap formed between the first rotor and the first stator,
The cooling fan on the other side is configured to suck in the fluid flowing out of the gap and discharge it toward the first cooling path,
An electric motor in which the number of poles of the auxiliary motor is set to be smaller than the number of poles of the main motor. The sub-motor is accommodated in a space formed between the axial end of the first rotor and the inner surface of the casing facing the end, and at least a part of the auxiliary motor is included in the first stator. The electric motor according to claim 1, wherein the electric motor is configured to be located inside.   The electric motor according to claim 1, wherein a permanent magnet is disposed on an outer peripheral portion of the first rotor.   The electric motor according to any one of claims 1 to 3, wherein a permanent magnet is disposed on an inner peripheral portion of the second rotor.   The electric motor according to any one of claims 1 to 4, wherein the auxiliary electric motor is connected to the same power source as the main electric motor.

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