WO2019189493A1

WO2019189493A1 - Motor

Info

Publication number: WO2019189493A1
Application number: PCT/JP2019/013410
Authority: WO
Inventors: 中村　吉伸
Original assignee: 日本電産株式会社
Priority date: 2018-03-28
Filing date: 2019-03-27
Publication date: 2019-10-03
Also published as: CN111919368A

Abstract

This motor is provided with a rotor having a shaft extending in a vertical direction, a stator positioned on the radially outer side of the rotor, and a housing accommodating the stator. The stator includes a core back, a plurality of teeth extending toward the radially inner side from the core back, and coils wound around the teeth. A hermetically sealed chamber enclosing a cooling medium is provided between the housing and the rotor. The hermetically sealed chamber has a plurality of outer circumferential side flow passages extending in the vertical direction, between the core back and the housing in the radial direction.

Description

motor

The present invention relates to a motor.

Conventionally, a motor equipped with a cooling mechanism is known in order to realize high load and long-time driving. Patent Document 1 discloses a configuration in which a motor is cooled by flowing a coolant directly to a coil.

Japanese Registered Patent No. 5962570

In the motor described above, an external pump was required to circulate the coolant inside the motor. For this reason, there is a problem that the entire system including the motor and the cooling device is enlarged.

One aspect of the present invention is to provide a motor with improved cooling efficiency without using an external pump.

A motor according to one aspect of the present invention includes a rotor having a shaft extending in a vertical direction, a stator located on the radially outer side of the rotor, and a housing that houses the stator. The stator includes a core back, a plurality of teeth extending radially inward from the core back, and a coil wound around the teeth. A sealed chamber in which a cooling medium is enclosed is provided between the housing and the rotor. The sealed chamber has a plurality of outer peripheral flow paths extending in the vertical direction between the core back and the housing in the radial direction.

According to the aspect of the present invention, a motor with improved cooling efficiency can be provided without using an external pump.

FIG. 1 is a cross-sectional view of a rotor blade device including a motor according to an embodiment. FIG. 2 is a perspective view illustrating a state in which the lid member is removed from the motor according to the embodiment. FIG. 3 is a perspective view of the stator holding member. FIG. 4 is a perspective view of the sealing member. FIG. 5 is a partial cross-sectional view of the motor showing the arrangement of the flow paths.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In the following description, the vertical direction in which the central axis J shown in FIG. One side of the central axis J in the axial direction is simply referred to as “upper side”, and the other side in the axial direction is simply referred to as “lower side”. The vertical direction is simply a name used for explanation, and does not limit the actual positional relationship or direction. In addition, a direction parallel to the central axis J is simply referred to as “axial direction”, a radial direction around the central axis J is simply referred to as “radial direction”, and a circumferential direction around the central axis J is simply referred to as “circumferential direction”. "

In this specification, “extending in the axial direction” includes not only the case of extending in the axial direction but also the case of extending in a direction inclined by less than 45 ° with respect to the axial direction. “Extending in the radial direction” includes not only strictly extending in the radial direction, that is, in a direction perpendicular to the axial direction, but also extending in a direction inclined by less than 45 ° with respect to the radial direction. .

As shown in FIG. 1, the rotary blade device 1 includes a motor 10, a propeller 2, and a fan 75. The rotary blade device 1 can be used as, for example, a drone rotary blade device. In this embodiment, the fan 75 is a centrifugal fan.
The motor 10 includes a housing 11,

bearings

23 and 24, a rotor 20, a stator 30, a circuit board 80, and a circuit board case 85.

The housing 11 has a cylindrical stator holding member 12 having a bottom wall portion 12 a that opens upward, a lid member 13 connected to the upper end of the stator holding member 12, and a seal positioned at the inner peripheral portion of the stator 30. And a stop member 14. The stator holding member 12 has a bearing holding portion 12b at the center of the bottom wall portion 12a when viewed in the axial direction. The bearing 23 is disposed inside the bearing holding portion 12b. In the case of this embodiment, the bearing holding part 12b has a plurality of through holes 12c penetrating the bearing holding part 12b in the axial direction.

The lid member 13 is fixed to the upper opening of the stator holding member 12. The lid member 13 has a bearing holding portion 13a. The lid member 13 holds the bearing 24 in the bearing holding portion 13a. In the present embodiment, the bearing holding portion 13a has a plurality of through holes 13b penetrating the bearing holding portion 13a in the axial direction. The rotor 20 and the stator 30 are accommodated in an internal space surrounded by the stator holding member 12 and the lid member 13.

The rotor 20 includes a shaft 21 and a rotor body 22. The shaft 21 is disposed along the central axis J. The shaft 21 has a cylindrical shape centered on the central axis J. The shaft 21 is supported by

bearings

23 and 24 so as to be rotatable around the central axis J. The upper end portion of the shaft 21 protrudes upward from the bearing 24. The fan 75 and the propeller 2 are fixed to the tip portion of the shaft 21 that protrudes upward from the lid member 13. The rotor body 22 includes a rotor core that is fixed to the outer peripheral surface of the shaft 21 and a rotor magnet that is fixed to the outer peripheral surface of the rotor core.

The stator 30 is opposed to the rotor 20 in the radial direction through a gap. The stator 30 includes a stator core 31 and a plurality of coils 35. The stator core 31 has an annular shape that surrounds the rotor body 22 on the radially outer side of the rotor body 22. The stator core 31 has a core back 32 and a plurality of teeth 33. The core back 32 has an annular shape centered on the central axis J. The teeth 33 protrude radially inward from the core back 32. The plurality of teeth 33 are arranged at equal intervals over one circumference along the circumferential direction.

The stator core 31 has an insulating layer on the surface of the stator core 31. The insulating layer insulates the coil 35 and the stator core 31. The stator 30 may include an insulator made of a resin molded body. The plurality of coils 35 are attached to each of the plurality of teeth 33.

The stator core 31 has a plurality of first groove portions 32a extending in the axial direction on the outer peripheral surface of the core back 32, as shown in FIGS. Each of the plurality of first groove portions 32 a is recessed from the outer peripheral surface of the core back 32 toward the inside in the radial direction. The housing 11 has a plurality of second groove portions 11 a extending in the axial direction on the inner peripheral surface of the stator holding member 12. Each of the plurality of second groove portions 11 a is recessed from the inner peripheral surface of the stator holding member 12 toward the radially outer side. The 1st groove part 32a and the 2nd groove part 11a are arrange | positioned facing radial direction. The housing 11 has a plurality of outer peripheral flow paths 41 each having a first groove portion 32a and a second groove portion 11a.

The outer periphery side flow path 41 is arrange | positioned in the position which overlaps with the teeth 33 seeing in radial direction. That is, it is located on the radially outer side of the teeth 33. Even if the first groove portion 32a constituting the outer peripheral flow path 41 is provided on the outer peripheral surface of the stator core 31 located on the radially outer side of the teeth 33, the width through which the magnetic lines pass is not easily reduced. Therefore, the influence on the magnetic characteristics due to the provision of the outer peripheral flow path 41 can be suppressed. Further, since the radial distance between the outer peripheral flow path 41 and the coil 35 is shortened, the coil 35 is easily cooled.

Moreover, in this embodiment, the outer peripheral side flow path 41 consists of the 1st groove part 32a and the 2nd groove part 11a, compared with the case where the outer peripheral side flow path 41 is provided only in the core back 32, the 1st of the core back 32 is provided. The depth of the groove 32a can be reduced. Thereby, the influence on the magnetic characteristic by providing the outer peripheral side flow path 41 can be further reduced. Moreover, since the outer peripheral side flow path 41 is arrange | positioned in the position nearer outside air by having the 2nd groove part 11a, the cooling medium which distribute | circulates an inside is easy to be cooled. In addition, the outer peripheral side flow path 41 may be comprised only by either one of the 1st groove part 32a or the 2nd groove part 11a.

As shown in FIG. 3, the stator holding member 12 has a plurality of step portions 121 that support the stator 30 from below on the inner wall surface of the stator holding member 12. The upper surfaces of the plurality of step portions 121 and the lower surface of the core back 32 are in contact with each other. The vertical height positions of the plurality of step portions 121 are the same as each other. In the case of the present embodiment, the step portion 121 supports the core back 32 of the stator core 31 from below. The plurality of step portions 121 are located between the two outer peripheral flow paths in the circumferential direction. According to this configuration, even in the motor 10 including the outer circumferential side channel 41, the stator 30 can be positioned in the axial direction by the step portion 121.

The housing 11 has a sealing member 14 located inside the core back 32 in the radial direction. The sealing member 14 covers at least the opening 33 b between adjacent teeth 33 facing the radially inner side of the stator 30. As shown in FIGS. 1, 2, and 4, the sealing member 14 includes a plurality of column portions 14a extending in the vertical direction at the inner peripheral end of the stator 30, and an upper annular portion 14b connected to the upper ends of the plurality of column portions 14a. And a lower annular portion 14c connected to the lower ends of the plurality of pillar portions 14a. The upper annular portion 14b and the lower annular portion 14c are annular with the central axis J as the center. The plurality of pillar portions 14a are located between the circumferential directions of the adjacent teeth 33. The rotor 20 is disposed inside the sealing member 14 in the radial direction.

In the case of this embodiment, the sealing member 14 is comprised by two members, the 1st member which consists of the pillar part 14a and the upper side annular part 14b, and the 2nd member which consists of the lower side annular part 14c. The column part 14a has side protrusions 14e that protrude in the circumferential direction from the side surface and extend in the vertical direction on both side surfaces facing in the circumferential direction. When the motor 10 is assembled, the column portion 14 a is inserted between the teeth 33 from the upper side of the stator core 31. As shown in FIG. 5, the side protrusion 14 e of the pillar 14 a is inserted into the groove 33 a located at the tip of the surface facing the circumferential direction of the teeth 33. In the fitting portion between the side protrusion 14e and the groove 33a, the contact surface between the pillar portion 14a and the tooth 33 is sealed.
In the present embodiment, the sealing member 14 does not cover the distal end surface facing the radially inner side of the teeth 33, so that the radial interval between the rotor 20 and the stator 30 can be reduced. Thereby, the torque of the motor 10 can be increased.

The lower annular portion 14c is fixed to the lower end portion of the column portion 14a by press-fitting or bonding. The lower annular portion 14 c is fixed to the upper surface of the bottom wall portion 12 a in the stator holding member 12. The bottom wall portion 12a has a cylindrical portion 12f extending upward from the upper surface of the bottom wall portion 12a. The cylindrical portion 12f is cylindrical with the central axis J as the center. As shown in FIG. 1, the lower annular portion 14c is fixed to the inner peripheral side of the cylindrical portion 12f by press-fitting or bonding. In the fitting portion between the cylindrical portion 12f and the lower annular portion 14c, the contact surface between the bottom wall portion 12a and the lower annular portion 14c is sealed.

The upper surface of the upper annular portion 14b of the sealing member 14 is bonded to the lower surface of the lid member 13 as shown in FIG. Thereby, in the upper part of the stator 30, the radially inner region of the sealing member 14 and the radially outer region of the sealing member 14 are sealed.

As shown in FIG. 5, the pillar portion 14 a has a protrusion 14 d that protrudes radially outward from a side surface facing the radially outer side of the pillar portion 14 a. In the case of this embodiment, the protrusion 14d has a triangular shape as viewed in the axial direction, and has a triangular prism shape extending in the vertical direction as a whole. The protrusion 14d has a corner that faces radially outward. By having the projecting portion 14d, the surface area of the surface of the column portion 14a facing the radially outer side is increased. Thereby, since the contact area of the pillar part 14a and a cooling medium increases, the heat dissipation to a cooling medium improves. In this embodiment, a part of coil 35 is arrange | positioned at the both sides of the circumferential direction of the protrusion part 14d. Since the circumferential interval between the tips of the teeth 33 is narrow, adjacent coils 35 are likely to come into contact with each other. However, in the present embodiment, the protrusions 14d hardly cause contact between the coils 35.

The motor 10 has an inner peripheral flow path 42 surrounded by the adjacent teeth 33 of the stator 30 and the column portion 14a of the sealing member 14. That is, the motor 10 includes a plurality of inner peripheral flow paths 42 positioned between the plurality of teeth 33 in the circumferential direction. The inner peripheral flow path 42 extends along the axial direction and penetrates the stator 30 in the up-down direction.

The lid member 13 has an upper flow path 43 formed of a recess recessed upward on the lower surface side of the lid member 13. The upper flow path 43 is connected to the upper ends of the plurality of outer peripheral flow paths 41 and the upper ends of the plurality of inner peripheral flow paths 42.
The stator holding member 12 has a lower flow path 44 between the stator 30 and the bottom wall portion 12a. The lower flow path 44 is connected to the lower ends of the plurality of outer peripheral flow paths 41 and the lower ends of the plurality of inner peripheral flow paths 42.

The motor 10 has a pressure adjusting device 100 at the bottom of the housing 11.
The pressure adjusting device 100 includes a cylindrical case portion 101 that extends downward from the outer peripheral surface of the bottom wall portion 12a, a sharp portion 102 that is fixed to an opening on the lower side of the case portion 101, and an interior of the case portion 101. And a pressure adjusting unit 103 to be disposed.

The partition wall 12d, which is a part of the bottom wall portion 12a, is located above the case portion 101. The partition wall 12 d partitions the internal space of the case portion 101 and the internal space of the stator holding member 12. The partition wall 12d has a through hole 12e that penetrates the partition wall 12d in the axial direction. The through hole 12 e connects the internal space of the case portion 101 and the internal space of the stator holding member 12.

The sharp portion 102 has a plate-like base portion 104 that expands in the radial direction, and a needle member 105 that protrudes upward from the upper surface of the base portion 104. Base portion 104 is fixed to the lower opening of case portion 101. The base portion 104 has a vent hole 104a that penetrates the base portion 104 in the axial direction.

The pressure adjusting unit 103 is a rubber-like or resin-made elastic sheet. The pressure adjustment unit 103 is fixed by being sandwiched between the case unit 101 and the base unit 104 in the lower opening of the case unit 101. The pressure adjusting unit 103 seals the lower opening of the case unit 101. The plane area of the pressure adjustment unit 103 is larger than the plane area of the lower opening of the case unit 101. The pressure adjustment unit 103 bends upward from the opening of the case unit 101 and is disposed along the inner surface of the case unit 101. An internal space of the case portion 101 that is sealed by the pressure adjusting unit 103 is a pressure adjusting chamber 46 of the pressure adjusting device 100. In the present embodiment, the pressure adjustment chamber 46 is disposed at a position overlapping the stator 30 when viewed in the axial direction. With this configuration, the pressure adjusting device 100 can be installed without increasing the radial dimension of the housing 11.

The motor 10 has a sealed chamber 40 in which a cooling medium is accommodated inside the housing 11. In the present embodiment, the sealed chamber 40 includes a cooling chamber 45 that cools the stator 30 and a pressure adjustment chamber 46 that is partitioned by the cooling chamber 45 and the partition wall 12d. The cooling chamber 45 includes an outer peripheral side channel 41, an inner peripheral side channel 42, an upper channel 43, and a lower channel 44 which are refrigerant channels in the stator holding member 12. In the pressure adjusting chamber 46, the pressure adjusting unit 103 is disposed, and the cooling chamber 45 and the pressure adjusting chamber 46 are connected via a through hole 12e that penetrates the partition wall 12d.

The cooling medium sealed in the housing 11 cools the coil 35 while circulating in the cooling chamber 45 of the sealed chamber 40. In the cooling chamber 45, the temperature of the cooling medium that contacts the coil 35, which is a heat generation source, first rises. The cooling medium heated by the coil 35 moves upward through the inner circumferential flow path 42 and reaches the upper flow path 43. In the upper flow path 43, the cooling medium flows radially outward while being in contact with the lid member 13 and being cooled. The cooling medium flows into the outer circumferential channel 41 that opens to the radially outer portion of the upper channel 43. The cooling medium moves downward while being cooled in the outer peripheral flow path 41. The cooling medium flows from the outer peripheral side channel 41 into the lower channel 44. In the lower flow path 44, the cooling medium moves radially inward and flows into the inner peripheral flow path 42 that opens to the lower flow path 44. In this way, the cooling medium discharges the heat inside the motor 10 to the lid member 13 and the stator holding member 12 while circulating in the housing 11 by the heat of the coil 35.

According to the motor 10 of the present embodiment, the contact area between the stator 30 and the cooling medium is increased by having the outer peripheral flow path 41 outside the core back 32. Thereby, the stator 30 can be efficiently cooled by the circulating cooling medium. Further, since the outer peripheral side flow path 41 is located immediately inside the stator holding member 12 and passes near the outside air, the cooling medium is easily cooled. Therefore, the cooling efficiency is improved as a whole.
Further, by circulating the cooling medium as described above, the cooling medium cooled in the outer peripheral flow path 41 can be smoothly circulated to the inner peripheral flow path 42 through the lower flow path 44. Thereby, it becomes easy to supply a low-temperature cooling medium to the coil 35 which is a heat generation source, and the cooling efficiency is improved.

The cooling chamber 45 of the present embodiment can enclose a cooling medium around the stator 30 by the stator holding member 12, the lid member 13, and the sealing member 14. Since the sealing structure can be realized using the minimum number of members, it can be manufactured easily and inexpensively.

In the present embodiment, the ceiling surface 43a of the upper flow path 43 may have an inclined surface portion that is inclined upward in the vertical direction toward the radially outer side. When bubbles are generated in the cooling medium, the bubbles pass through the inner peripheral flow path 42 and reach the ceiling surface 43 a of the upper flow path 43. Here, if the ceiling surface 43a is increased radially outward, the bubbles are guided radially outward. Thereby, it becomes easy to flow radially outward in the upper flow path 43, and the circulation of the cooling medium becomes smoother.

The pressure adjusting unit 103 of the pressure adjusting device 100 is deformed in a range not reaching the sharp part 102 during the normal operation of the motor 10, and absorbs the volume change of the cooling medium.
On the other hand, when the internal pressure of the cooling medium increases excessively due to abnormal vaporization of the cooling medium, the pressure adjusting unit 103 protrudes further downward than during normal operation, and the convex tip of the pressure adjusting unit 103 is the sharp part 102. The needle member 105 is contacted. As a result, a hole is made in the pressure adjusting unit 103. A part of the cooling medium is released from the hole formed in the pressure adjusting unit 103, and the internal pressure of the cooling medium is released. As a result, damage to the motor 10 due to the internal pressure of the cooling medium is suppressed.

A bus bar holder 50 is disposed on the bottom surface of the bottom wall portion 12a. The bus bar holder 50 holds a plurality of bus bars 51. The bottom wall portion 12a has a through hole 12e that penetrates the bottom wall portion 12a in the axial direction at a position overlapping the bus bar holder 50 when viewed in the axial direction. Lead wires 35a extending from the plurality of coils 35 extend to the bus bar holder 50 through the through holes 12e. Leader line 35 a is connected to bus bar 51 in bus bar holder 50.

The circuit board case 85 is fixed to the lower part of the housing 11. The circuit board case 85 has a bottom wall and has a cylindrical shape that opens upward. A circuit board 80 is accommodated in the bottom of the circuit board case 85. The circuit board 80 has a plate shape extending in the radial direction. The circuit board 80 is connected to the bus bar 51. The circuit board case 85 has a plurality of openings 85a on the side surface. The pressure adjusting device 100 at the bottom of the housing 11 is located above the circuit board case 85.

In the rotary blade device 1 of the present embodiment, the propeller 2 and the fan 75 are rotationally driven by the motor 10. The fan 75 circulates cooling air inside the motor 10. As the fan 75 rotates, the air above the motor 10 is blown outward in the radial direction, so that the pressure in the vicinity of the bearing 24 on the radial inner side of the fan 75 decreases. Thereby, the air in the circuit board case 85 under the motor 10 moves from the through hole 12c of the bearing holding part 12b to the through hole 13b of the bearing holding part 13a through the periphery of the rotor 20. Therefore, the rotary blade device 1 has a cooling air flow path that enters from the opening 85 a of the circuit board case 85, passes through the inside of the motor 10, and goes out of the fan 75.

In the disclosure of the present invention, the description has been made with reference to the drawings. However, the configuration of each component can be changed as appropriate without being limited to the described embodiment. In the present embodiment, an example in which the sealing member is constituted by two members has been shown, but the present invention is not limited thereto. For example, the sealing member may be provided by mold resin or aluminum die casting by insert molding the stator. In this case, the stator and the sealing member are molded as an integrated single member.

Further, the sealing member may be configured by only a plurality of pillar portions positioned between the circumferential directions of adjacent teeth. In this case, the stator holding member may have a lower annular portion, and the lid member may have an upper annular portion. The plurality of column portions may be fixed to an upper annular portion and a lower annular portion provided on the upper surface of the stator holding member and the lower surface of the lid member.

DESCRIPTION OF SYMBOLS 10 ... Motor, 11 ... Housing, 11a ... 2nd groove part, 12 ... Stator holding member, 13 ... Cover member, 14 ... Sealing member, 14a ... Column part, 14b ... Upper annular part, 14c ... Lower annular part, 14d ... Projection, 20 ... Rotor, 21 ... Shaft, 30 ... Stator, 32 ... Core back, 32a ... First groove, 33 ... Teeth, 33a ... Groove, 33b ... Opening, 35 ... Coil, 40 ... Sealed chamber, 41 ... outer peripheral side flow path, 42 ... inner peripheral side flow path, 43 ... upper flow path, 43a ... ceiling surface, 44 ... lower flow path, 121 ... stepped portion

Claims

A rotor having a shaft extending in a vertical direction;
A stator located radially outside the rotor;
A housing that houses the stator;
With
The stator has a core back, a plurality of teeth extending radially inward from the core back, and a coil wound around the teeth,
A sealed chamber in which a cooling medium is enclosed is provided between the housing and the rotor,
The sealed chamber has a plurality of outer peripheral flow paths extending in a vertical direction between the core back and the housing in the radial direction.
motor.
The outer peripheral flow path overlaps the teeth as seen in the radial direction,
The motor according to claim 1.
The outer peripheral flow path includes a first groove provided on the outer peripheral surface of the core back, and a second groove provided on the inner peripheral surface of the housing so as to face the first groove in the radial direction.
The motor according to claim 1 or 2.
The sealed chamber is
In the circumferential direction, an inner peripheral flow path located between the plurality of teeth;
An upper flow path connecting the inner peripheral flow path and the outer peripheral flow path on the upper side of the core back;
A lower flow path connecting the inner peripheral flow path and the outer peripheral flow path below the core back;
Having
The motor according to any one of claims 1 to 3.
The ceiling surface of the upper channel has an inclined surface portion that is inclined upward in the vertical direction as it goes radially outward.
The motor according to claim 4.
The housing is
A stator holding member covering the outer periphery and the lower surface of the stator;
A sealing member that covers at least an opening between the teeth that opens radially inward of the stator;
A lid member connected to the upper end of the stator holding member and the upper end of the sealing member and covering the upper surface of the stator;
Having
The motor according to claim 4 or 5.
The sealing member is
A plurality of pillars extending in the vertical direction at the inner peripheral end of the stator;
An upper annular portion connected to upper ends of the plurality of pillar portions;
A lower annular portion connected to lower ends of the plurality of pillar portions;
Have
The inner circumferential flow path is located on the radially outer side than the plurality of column portions,
The motor according to claim 6.
The column portion has a protruding portion extending radially outward.
The motor according to claim 7.
The stator holding member has a plurality of step portions that support the stator from below on an inner wall surface of the stator holding member,
The step portion is located between the two outer peripheral flow paths in the circumferential direction.
The motor according to any one of claims 6 to 8.