Rotor and motor equipped with same

Abstract

This prevents heat generated near the brush and commutator from being transmitted to the annular resistor. [Solution] A rotor that rotates integrally with a motor shaft includes a core around which a winding is wound, a commutator having terminals to which ends of the winding are connected, and an annular resistor arranged to surround the outer periphery of the commutator. The commutator has a plurality of commutator pieces arranged at predetermined intervals along the circumferential direction of the shaft, and a plurality of risers formed by folding back the plurality of commutator pieces and arranged to extend in the radial direction of the shaft. The annular resistor is supported by linear conductors that are connected to the risers and arranged to extend in the radial direction of the shaft, and the inner diameter of the annular resistor is larger than an imaginary circle connecting the radially outer ends of the plurality of risers in a plan view perpendicular to the axial direction of the shaft.

Description

[Technical Field]

[0001] The present invention relates to a rotor that rotates integrally with a motor shaft and a motor including the rotor, and more particularly to a rotor having an annular resistor that is arranged so as to surround the outer periphery of a commutator, and a motor including the rotor. [Background technology]

[0002] In brushed motors, rotation is sustained by the commutation of electricity between the brushes and the commutator, but when the brushes move between adjacent commutator pieces and the flow of electricity switches, sparks (spark discharges) can occur, and these sparks can cause electrical noise.

[0003] Sparks are generated by unstable tracking or overload current at the sliding contact area between the brush and commutator, and it is known that sparks are more likely to occur when an insulating coating or the like is formed at the sliding contact area between the brush and commutator, as this makes the electrical contact between the brush and commutator unstable.

[0004] Electrical noise caused by sparks can be reduced by attaching capacitors or choke coils to the terminals of the motor, but a more common and cost-effective method is to attach an annular resistor known as a disk varistor or ring varistor near the commutator, which is closer to the source of the sparks, to convert the high-voltage electrical energy that causes sparks into thermal energy and effectively eliminate it.

[0005] For example, Patent Document 1 discloses a rotor that includes an annular resistor arranged to surround the outer periphery of a commutator, and an annular printed circuit board having a circumferential wiring pattern on one surface that shorts out specific commutator pieces that make up the commutator so that they are at the same potential, and a radial wiring pattern on the other surface that extends radially so that the electrodes of the annular resistor are connected to each of the commutator pieces. In this rotor, the electrodes of the annular resistor are aligned with the radial wiring patterns in the circumferential direction, and are electrically connected to each other by soldering that overcomes the thickness of the annular resistor, thereby mounting the annular resistor on the printed circuit board.

[0006] On the other hand, in recent years, the voltage of batteries installed in automobiles has been increasing. In other words, if the handling power is the same, a higher voltage battery will result in a smaller current, which will enable the reduction of the diameter and weight of various electric wires and harnesses, which will be advantageous from the viewpoints of improving fuel efficiency and reducing the environmental load. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 5525915 Summary of the Invention [Problem to be solved by the invention]

[0008] As the battery voltage increases, the input voltage to the motor also increases, which in turn increases the spark voltage, increasing the thermal energy generated by the spark. This may make the annular resistor more susceptible to damage due to factors such as differences in the linear expansion coefficient between the annular resistor and other components.

[0009] Therefore, the inventors have come up with the technical idea that it is desirable to suppress as much as possible the heat transfer to the annular resistor other than that caused by the heat energy generated when eliminating electrical noise, and to reduce the physical stress on the annular resistor.

[0010] In particular, the inventors have found that it is difficult to completely eliminate sparks even when an annular resistor is installed, and if a spark does occur, the areas near the brush and commutator may temporarily become very hot due to Joule heat caused by the spark.

[0011] In light of these technical ideas, in the invention described in Patent Document 1, although the inner diameter of the annular resistor itself is sufficiently large and it is positioned physically separated from the brush and commutator, the printed circuit board is close to the brush and commutator, so it can be said that the printed circuit board is positioned in an environment where it is susceptible to Joule heat caused by sparks.

[0012] Furthermore, since the entire surface of the annular resistor is in contact with the other surface of the printed circuit board, no matter how far the distance is between the annular resistor and the brush and commutator, the Joule heat received by the printed circuit board is easily transferred directly to the annular resistor.

[0013] The present invention was devised in view of these problems, and aims to suppress the transfer of heat generated near the brush and commutator to the annular resistor. However, this is not the only aim, and another aim of the present invention is to achieve effects that cannot be obtained by conventional techniques, which are derived from the configurations shown in the following description of the preferred embodiment of the present invention. [Means for solving the problem]

[0014] The disclosed motor can be realized as the following embodiments (application examples) that solve at least some of the above problems. From embodiment 2 onwards, each embodiment can be selected as an additional embodiment, and none of them discloses an embodiment or configuration that is essential to the present invention.

[0015] Aspect 1. The disclosed rotor is a rotor that rotates integrally with the shaft of a motor, and comprises a core around which a winding is wound, a commutator having terminals to which ends of the winding are connected, and an annular resistor arranged to surround the outer periphery of the commutator, wherein the commutator has a plurality of commutator pieces arranged at predetermined intervals along the circumferential direction of the shaft, and a plurality of risers formed by folding back the plurality of commutator pieces and arranged to extend radially of the shaft, wherein the annular resistor is supported by linear conductors connected to the risers and arranged to extend radially of the shaft, and the inner diameter of the annular resistor is larger than an imaginary circle connecting the radially outer ends of the plurality of risers when viewed in a plane perpendicular to the axial direction of the shaft.

[0016] Aspect 2. In the above aspect 1, the linear conductor is preferably a copper wire.

[0017] Aspect 3: The disclosed motor comprises a rotor as described in aspect 1 or 2 above, and a housing in which the rotor is housed, wherein the rotor has a fan housed in the housing and rotates integrally with the shaft, and the housing preferably has a through hole formed at a position that overlaps with the annular resistor when viewed in a cross section along the axial direction of the shaft.

[0018] Aspect 4. In the above aspect 3, it is preferable that the housing is formed in a bottomed cylindrical shape with an opening at one end in the axial direction of the shaft and further includes a small case arranged to cover the opening, the small case having an air hole connecting the inside and outside spaces of the housing, the fan having first and second fan rings arranged at a predetermined interval along the axial direction of the shaft, a connection portion arranged to connect between the first fan ring and the second fan ring, and a ventilation hole formed in the connection portion, and the ventilation hole is arranged in a position overlapping the annular resistor and the through hole in a cross-sectional view along the axial direction of the shaft. [Effects of the Invention]

[0019] The disclosed rotor and motor including the same can prevent heat generated near the brushes and commutator from being transferred to the annular resistor. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 is a side view of a motor according to an embodiment. [Figure 2] 2 is a front view of the motor of FIG. 1 as viewed from one axial end side. [Figure 3] 2 is a front view of a rotor applied to the motor of FIG. 1, viewed from one axial end side. FIG. [Figure 4] 2A is a front view and FIG. 2B is a side view of a fan applied to the motor of FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0021] A rotor and a motor including the rotor will be described as an embodiment with reference to the drawings. The following embodiment is merely an example, and is not intended to exclude various modifications and technical applications not explicitly stated in the following embodiment. The configurations of the present embodiment can be modified in various ways without departing from the spirit of the invention. Furthermore, they can be selected or combined as needed.

[0022] [1. Configuration] 1 is a side view of a motor 1 of this embodiment. The motor 1 includes a shaft 1S as an output shaft. Hereinafter, the direction in which the shaft 1S extends will be referred to as the axial direction (or one axial end side or the other axial end side), the direction perpendicular to the axial direction and away from the center of rotation of the shaft 1S and toward the center of rotation will be referred to as the radial direction (or radially outward or radially inward), and the direction perpendicular to the axial direction and going around the center of rotation of the shaft 1S will be referred to as the circumferential direction.

[0023] The motor 1 is, for example, a permanent magnet field type DC motor 1 having an inner rotor 3 with brushes 4a, and includes a cylindrical housing 2 with a bottom, an end bell 4, a small case 5, and a rotor 3. The housing 2 is formed in a cylindrical shape with a bottom, with an opening 2 at one axial end of the shaft 1S. The housing 2 accommodates the end bell 4 to which an electric element is attached, the small case 5 arranged to cover the opening 2 of the housing 2, and the rotor 3 which rotates integrally with the shaft 1S. The end bell 4 is accommodated at one axial end of the housing 2. The small case 5 is accommodated further toward the one axial end than the end bell 4. That is, in this embodiment, the side where the end bell 4 is arranged is referred to as the "one axial end" and the opposite side (the bottom side of the housing 2) is referred to as the "other axial end."

[0024] The housing 2 has an opening 2 at one end in the axial direction of the shaft 1S. A rotor 3, a fan 9 that rotates integrally with the shaft 1S, and a stator are housed inside the housing 2 through this opening 2. As shown in FIG. 1, the housing 2 also has a through-hole 2h formed at a position that overlaps with an annular resistor 8 (described below) in a cross-sectional view taken along the axial direction of the shaft 1S. The through-hole 2h is used as a hole for dissipating heat generated inside the motor 1 to the outside. The bottom portion of the housing 2 also has a bearing 2m that supports the other axial end of the shaft 1S.

[0025] The end bell 4 has an electric element attached thereto and supports one end of the brush 4a arm. The other end of the brush 4a arm supports the brush 4a. The brush 4a is a member that passes externally supplied electricity to the commutator 7 and is made of, for example, a member primarily composed of carbon. The electricity is supplied from a power source external to the motor 1 and is passed through a power supply terminal that protrudes from one axial end of the end bell 4, the brush 4a arm that supports the brush 4a, and the brush 4a, in that order, before being supplied to the commutator 7.

[0026] As shown in FIG. 2, the small case 5 is arranged to cover the opening 2 of the housing 2. The small case 5 also has air holes 5h that connect the interior and exterior spaces of the housing 2. The air holes 5h function as inlets for the flow path of the air generated by the rotation of the fan 9. The small case 5 of this embodiment has a total of four air holes 5h, each of which has a substantially trapezoidal shape. The air holes 5h are arranged in positions that overlap with other components arranged in the end bell 4 when viewed in the axial direction.

[0027] The small case 5 also has a flat plate-like plane portion 5a that extends perpendicular to the axial direction. The plane portion 5a has an outer shape that corresponds to the shape of the opening 2 of the housing 2, and the above-mentioned air holes 5h are formed in the plane portion 5a. The small case 5 also has a bearing 5m that supports one axial end of the shaft 1S.

[0028] 3, the rotor 3 is rotated integrally with the shaft 1S and includes a core 6 around which a winding 10 is wound, a commutator 7 having terminals to which ends of the winding 10 are connected, and an annular resistor 8 disposed so as to surround the outer periphery of the commutator 7. The rotor 3 also includes a fan 9 that is accommodated in the housing 2 and rotates integrally with the shaft 1S.

[0029] The rotor 3 is supported by a bearing 2m provided at the other axial end of the housing 2 and a bearing 5m provided in the small case 5, and rotates integrally with the shaft 1S. Therefore, in the motor 1 of this embodiment, as the rotor 3 rotates, the core 6, commutator 7, annular resistor 8, and fan 9 rotate integrally with the shaft 1S.

[0030] The core 6 includes an insertion hole through which the shaft 1S (not shown) is inserted, and teeth each having a pillar portion 6a projecting radially outward from the rotation axis and a blade portion 6b extending circumferentially from the radially outer end of the pillar portion 6a. A winding 10 is wound around the core 6.

[0031] The core 6 is made by laminating multiple steel plates of the same shape, and the stacking direction of the steel plates is the same as the extending direction of the rotating shaft. For example, one end of the winding 10 is connected to a riser 7b (described later), and the winding is wound around the column portion 6a, and then the other end is connected to the riser 7b to wind the winding, thereby forming a coil.

[0032] The commutator 7 is a component that rectifies the electricity supplied to the coils in accordance with the rotation of the rotor 3, i.e., the rotation angle of the rotor 3, and is attached to one end of the shaft 1S. The commutator 7 commutates the electricity between the brushes 4a and the commutator 7, and the rotation of the motor 1 is maintained.

[0033] The commutator 7 has a plurality of commutator pieces 7a arranged at predetermined intervals along the circumferential direction of the shaft 1S, and a plurality of risers 7b formed by folding back the plurality of commutator pieces 7a and arranged to extend radially of the shaft 1S.

[0034] The commutator pieces 7a are formed, for example, in the shape of an arcuate surface or a similar shape. The commutator 7 is formed by arranging a plurality of commutator pieces 7a at predetermined intervals along the circumferential direction of the shaft 1S.

[0035] Since the commutator 7 is made up of multiple commutator pieces 7a, the commutator pieces 7a that come into contact with the brushes 4a change according to the rotation of the rotor 3, i.e., the rotation angle of the rotor 3, and the coils to which electricity is supplied from the brushes 4a change accordingly, thereby maintaining the rotation of the motor 1.

[0036] The riser 7b is formed by folding back one end of the commutator piece 7a, which extends toward the other axial end, toward the one axial end, forming a roughly U-shape. The riser 7b has an inner circumferential surface 7bi, which faces inward when the commutator piece 7a is folded back, and an outer circumferential surface 7bo, which faces outward. One end of the winding 10 wound around the core 6 is positioned on the inner circumferential surface 7bi side. After winding, resistance welding is performed by applying pressure from the outer circumferential surface 7bo side while passing a current through the winding 10, thereby melting the outer coating of the winding 10 with the generated resistance heat. This electrically connects the riser 7b and the winding 10.

[0037] The annular resistor 8 is disposed so as to surround the outer periphery of the commutator 7. The annular resistor 8 is supported by linear conductors 11 that are connected to the risers 7b and disposed so as to extend in the radial direction of the shaft 1S, and the inner diameter of the annular resistor 8 is larger than an imaginary circle 12 that connects the radially outer ends of the plurality of risers 7b in a plan view perpendicular to the axial direction of the shaft 1S.

[0038] The annular resistor 8 is a component that reduces the occurrence of sparks (spark discharges) that occur when the brush 4a transitions between adjacent commutator pieces 7a and the flow of electricity switches. The annular resistor 8 is also referred to as a disk varistor or a ring varistor.

[0039] The linear conductor 11 is a linear member that electrically connects the commutator 7 and the annular resistor 8. In this embodiment, one end of the linear conductor 11 is connected to the outer circumferential surface 7bo of the riser 7b by welding, and the other end is connected to the annular resistor 8 by soldering.

[0040] As shown in FIG. 3, the imaginary circle 12 is an imaginary circle drawn by connecting the radially outer ends of the plurality of risers 7b when viewed from above, with the inner diameter of the annular resistor 8 perpendicular to the axial direction of the shaft 1S. In this embodiment, the imaginary circle 12 is a circle connecting the radially outer ends of the risers 7b after they have been deformed by resistance welding. Note that the shape of the risers 7b on which the imaginary circle 12 is formed is not limited to the shape after they have been deformed by resistance welding, and may simply be a shape that protrudes radially outward. Furthermore, the positional relationship between the protruding direction of the risers 7b and the protruding direction of the column portion 6a shown in FIG. 3 is merely an example, and is not limited to the positional relationship shown in FIG. 3.

[0041] The annular resistor 8 is supported by a linear conductor 11 that is connected to the riser 7b and arranged to extend radially of the shaft 1S, and the inner diameter of the annular resistor 8 is larger than an imaginary circle 12 that connects the radially outer ends of the multiple risers 7b when viewed in a plane perpendicular to the axial direction of the shaft 1S.

[0042] As a result, the annular resistor 8 is physically separated from the brush 4a and the commutator 7 by the linear conductor 11. Furthermore, since the member that conducts the heat generated near the brush 4a and the commutator 7 is linear, it is possible to prevent the heat generated near the brush 4a and the commutator 7 from being transmitted to the annular resistor 8. Furthermore, since it is possible to suppress the conduction of heat to the annular resistor 8, it is possible to suppress damage to the annular resistor 8 due to differences in the linear expansion coefficient between the annular resistor 8 and other members.

[0043] In this embodiment, a copper wire (for example, a plated annealed copper wire) is used as the linear conductor 11, but the material is not limited to this as long as it is conductive and can support the annular resistor 8. Examples include solder wire, aluminum wire, and gold wire.

[0044] When a copper wire is used as the linear conductor 11, the copper wire is less likely to shrink when heated, facilitating welding and soldering. Furthermore, since the copper wire is less likely to shrink, the linear conductor 11 can be extended further radially outward from the outer circumferential surface 7bo of the riser 7b, thereby supporting the annular resistor 8 further radially outward. This further reduces the transfer of heat generated near the brush 4a and the commutator 7 to the annular resistor 8.

[0045] The rotor 3 of this embodiment has a fan 9 that is housed in the housing 2 and rotates integrally with the shaft 1S. The fan 9 rotates integrally with the shaft 1S to generate an airflow path and expel air from inside the motor 1 to the outside of the motor 1. The housing 2 of this embodiment also has a through-hole 2h formed in a position that overlaps with the annular resistor 8 in a cross-sectional view taken along the axial direction of the shaft 1S.

[0046] In this case, the through holes 2h function as air outlets, allowing heat generated near the brushes 4a and the commutator 7 to be released to the outside of the motor 1. Furthermore, the through holes 2h are formed at positions that overlap with the annular resistor 8 in a cross-sectional view along the axial direction of the shaft 1S, so the annular resistor 8 is positioned close to the through holes 2h. Therefore, even if heat generated near the brushes 4a and the commutator 7 is transferred to the annular resistor 8, it can be released to the outside of the motor 1. Furthermore, heat generated when the annular resistor 8 eliminates electrical noise can also be released to the outside of the motor 1.

[0047] As shown in FIG. 4, the fan 9 of this embodiment includes a first fan ring 9a and a second fan ring 9b spaced a predetermined distance apart along the axial direction of the shaft 1S, a connecting portion 9c connecting the first fan ring 9a and the second fan ring 9b, and ventilation holes 9e formed in the connecting portion 9c. The first fan ring 9a and the second fan ring 9b are each circular and arranged coaxially around the shaft 1S. The inner diameter of the first fan ring 9a is larger than the inner diameter of the second fan ring 9b. The connecting portion 9c is located axially between the first and second fan rings 9b and is formed with multiple connecting portions 9d and multiple ventilation holes 9e. The connecting portion 9c has multiple ventilation holes 9e, and the remaining portion serves as the connecting portion 9d.

[0048] The ventilation holes 9e are positioned so as to overlap the annular resistor 8 and the through-holes 2h in a cross-sectional view taken along the axial direction of the shaft 1S. That is, the annular resistor 8 is positioned axially between the first fan ring 9a and the second fan ring 9b. It can also be said that the annular resistor 8 is housed in the fan 9. This creates an airflow path in which air is taken in through the air holes 5h in the small case 5 and released through the through-holes 2h, and the annular resistor 8 is positioned within the airflow path. This allows heat generated near the brush 4a and the commutator 7, as well as heat generated when the annular resistor 8 eliminates electrical noise, to be released to the outside of the motor 1.

[0049] [2.Effects] (1) In the rotor 3 described above, the annular resistor 8 is supported by a linear conductor 11 connected to the riser 7b and arranged to extend radially of the shaft 1S, and the inner diameter of the annular resistor 8 is larger than the imaginary circle 12 connecting the radially outer ends of the multiple risers 7b when viewed in a plane perpendicular to the axial direction of the shaft 1S.

[0050] As a result, the annular resistor 8 is disposed so as to be physically separated from the brush 4a and the commutator 7 by the linear conductor 11. Furthermore, the annular resistor 8 is connected to the commutator 7 by the linear conductor 11. Therefore, since the member that conducts the heat generated near the brush 4a and the commutator 7 is linear, it is possible to prevent the heat from being transmitted to the annular resistor 8. Furthermore, since it is possible to prevent the conduction of heat to the annular resistor 8, it is possible to prevent damage to the annular resistor 8 due to differences in the linear expansion coefficient between the annular resistor 8 and other members.

[0051] (2) In the rotor 3 described above, the linear conductors 11 are copper wires. An example of the copper wire is a plated annealed copper wire.

[0052] When a copper wire is used as the linear conductor 11, the copper wire is less likely to shrink when heated, facilitating welding and soldering. Furthermore, since the copper wire is less likely to shrink, the linear conductor 11 can be extended further radially outward from the outer circumferential surface 7bo of the riser 7b, thereby supporting the annular resistor 8 further radially outward. This further reduces the transfer of heat generated near the brush 4a and the commutator 7 to the annular resistor 8.

[0053] (3) The above-mentioned rotor 3 is applied to the above-mentioned motor 1, and the applied rotor 3 has a fan 9 that is accommodated in a housing 2 and rotates integrally with the shaft 1S, and the housing 2 has a through hole 2h formed at a position that overlaps with the annular resistor 8 when viewed in a cross-section along the axial direction of the shaft 1S. This allows heat generated near the brushes 4a and the commutator 7 to be released to the outside of the motor 1 even if it is transferred to the annular resistor 8. Furthermore, heat generated when the annular resistor 8 eliminates electrical noise can also be released to the outside of the motor 1.

[0054] (4) Furthermore, in the above-described motor 1, the small case 5 has an air hole 5h that connects the inside and outside spaces of the housing 2, and the air vent 9e is positioned so as to overlap with the annular resistor 8 and the through hole 2h when viewed in a cross section along the axial direction of the shaft 1S.

[0055] This creates an airflow path where air is taken in through the air holes 5h in the small case 5 and released through the through holes 2h, and the annular resistor 8 is placed inside the airflow path. This allows heat generated near the brush 4a and the commutator 7, as well as heat generated when the annular resistor 8 eliminates electrical noise, to be released outside the motor 1.

[0056] [3. Other] The rotor 3 and motor 1 described above are merely examples, and are not limited to the above configurations. For example, the linear conductor 11 does not have to be a copper wire, but may be a solder wire, an aluminum wire, or a gold wire.

[0057] In either case, the annular resistor 8 is disposed physically separated from the brush 4a and the commutator 7, and is connected to the commutator 7 by a linear conductor. This prevents the generated heat from being transferred to the annular resistor 8. Furthermore, since the transfer of heat to the annular resistor 8 can be prevented, damage to the annular resistor 8 caused by differences in the linear expansion coefficient between the annular resistor 8 and other components can be prevented.

[0058] Furthermore, the rotor 3 does not need to have the fan 9. In this case, the annular resistor 8 can be disposed further radially outward than when the annular resistor 8 is housed in the fan 9. In other words, the annular resistor 8 is disposed physically further apart from the brush 4a and the commutator 7. Furthermore, the housing 2 does not need to have the through-hole 2h. Furthermore, the small case 5 does not need to have the air hole 5h.

[0059] Furthermore, in a cross-sectional view along the axial direction of the shaft 1S, the ventilation holes 9e, the annular resistor 8, and the through-holes 2h do not have to be positioned to overlap each other. In other words, the annular resistor 8 does not have to be positioned axially between the first and second fan rings 9b.

[0060] Furthermore, in this embodiment, the brushes 4a of the end bells 4 are disposed radially outward of the commutator 7, but this is not limiting as long as electricity can be supplied from the power supply terminals to the commutator 7. One example is a so-called fork brush, in which the members electrically connecting the power supply terminals and the commutator 7 are all made of metal. [Explanation of symbols]

[0061] 1 motor 1S shaft 2. Housing 2a opening 2h through hole 2m bearing 3 rotors 4 End Bell 4a brush 4b Brush arm 5 small cases 5a Flat part 5h Wind Cave 5m bearing 6 cores 6a Insertion hole 6b Pillar part 6c Wing 7 Commitator 7a Commutator piece 7b Liza 7bi Inner surface 7bo outer surface 8 Ring resistor 9 Fans 9a First Fun Ring 9b Second Fan Ring 9c Connection 9e Ventilation hole 10 windings 11 Linear conductor 12 Virtual Circle

Claims

1. A rotor that rotates integrally with the motor shaft, a core around which a winding is wound; a commutator having terminals to which the ends of the windings are connected; an annular resistor disposed so as to surround the outer periphery of the commutator; Equipped with the commutator includes a plurality of commutator pieces arranged at predetermined intervals along the circumferential direction of the shaft, and a plurality of risers formed by folding back the plurality of commutator pieces and arranged to extend in the radial direction of the shaft, The annular resistor is supported by a linear conductor connected to the riser and arranged to extend in a radial direction of the shaft, and an inner diameter of the annular resistor is larger than an imaginary circle connecting radially outer ends of the plurality of risers in a plan view perpendicular to the axial direction of the shaft. A rotor characterized by:

2. The linear conductor is a copper wire. The rotor of claim 1 .

3. A rotor according to claim 1 or 2; a housing in which the rotor is accommodated; Equipped with the rotor has a fan accommodated in the housing and rotated integrally with the shaft, The housing has a through hole formed at a position overlapping the annular resistor in a cross section along the axial direction of the shaft. Motor.

4. The housing is formed in a cylindrical shape with a bottom and an opening at one end in the axial direction of the shaft, Further provided is a small case arranged to cover the opening, the small case has a ventilation hole that connects the inside and outside spaces of the housing, The fan has first and second fan rings arranged at a predetermined interval along the axial direction of the shaft, a connection portion arranged to connect the first fan ring and the second fan ring, and a ventilation hole formed in the connection portion, and the ventilation hole is arranged at a position overlapping the annular resistor and the through hole in a cross-sectional view along the axial direction of the shaft. The motor according to claim 3.

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