Rotary machine

Abstract

To provide a rotary machine in which electric resistance is reduced while prolonging the lifetime of a brush.SOLUTION: A rotating machine includes a stator, a rotor, a rotating shaft, a brush 70, and an elastic body SP. The stator generates a rotating magnetic field when the winding is energized. The rotor is rotated by the rotating magnetic field. The rotating shaft is connected to the rotor. The brush 70 is in sliding contact with the rotating shaft and is electrically connected to the housing (grounding body) to electrically conduct the rotating shaft and the grounding body. The elastic body SP presses the brush 70 against the rotary shaft. A plurality of brushes 70 are arranged in the circumferential direction of the rotating shaft.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The disclosure in this specification relates to a rotating machine having a brush that slides on a rotating shaft. [Background technology]

[0002] Patent Document 1 describes that the rotating shaft of the motor is electrically grounded by bringing a brush into sliding contact with the rotating shaft, thereby suppressing the external radiation of high-frequency noise generated by the inverter. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-250583 Summary of the Invention [Problem to be solved by the invention]

[0004] When the brush is brought into sliding contact with the rotating shaft, the stronger the force (pressing force) that presses the brush against the rotating shaft, the lower the electrical resistance at the contact point between the brush and the rotating shaft. However, the trade-off is that the stronger the pressing force, the more severe the brush wear and the shorter the brush lifespan.

[0005] One disclosed object is to provide a rotating machine that achieves both reduced electrical resistance and a longer brush life. [Means for solving the problem]

[0006] In order to achieve the above object, a rotating machine according to one aspect of the present disclosure includes: a stator (30) that generates a rotating magnetic field when current is applied to a winding (32); a rotor (40) that rotates due to a rotating magnetic field; a rotating shaft (50) connected to the rotor; a brush (70) that is in sliding contact with the rotating shaft and is electrically connected to the grounding body (20), thereby electrically conducting the rotating shaft and the grounding body; an elastic body (SP) that presses the brush against the rotary shaft; A plurality of brushes are arranged in a line in the circumferential direction of the rotary shaft.

[0007] In the rotating machine disclosed herein, multiple brushes are arranged in a line around the rotating shaft. Therefore, compared to a single brush, the force pressing the brush against the rotating shaft (pressing force) is not increased, and the electrical resistance at the contact point between the brush and the rotating shaft can be reduced. This makes it possible to achieve both reduced electrical resistance and a longer brush life.

[0008] The reference numbers in parentheses above merely indicate an example of the correspondence with specific configurations in the embodiments described below, and do not in any way limit the technical scope. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view of a rotating machine according to a first embodiment. [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Figure 3] FIG. 2 is an electric circuit diagram illustrating a voltage path of the rotating machine shown in FIG. [Figure 4] FIG. 2 is a plan view of the brush structure in the first embodiment, seen from the axial direction with the sealing material removed. [Figure 5] 5 is a plan view of the elastic body shown in FIG. 4 when viewed alone from the axial direction. [Figure 6] FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. [Figure 7] FIG. 2 is a plan view of the brush structure in the first embodiment, seen from the axial direction with the sealing material and elastic body removed. [Figure 8] 5 is a plan view of the brush structure, showing the brush shown in FIG. 4 in a state where it has worn down and become smaller. [Figure 9]FIG. 7 is a cross-sectional view of the brush structure, showing the state in which the brush shown in FIG. 6 has worn down and become smaller. [Figure 10] 10 is a graph of test results showing the degree to which shaft voltage is reduced by the brush structure according to the present embodiment. [Figure 11] 10 is a graph of test results showing impedance and phase of a brush structure according to the present embodiment. [Figure 12] 10 is a graph showing the relationship between the electrical resistance and the surface pressure of the brush. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, several embodiments for carrying out the present disclosure will be described with reference to the drawings. In each embodiment, parts corresponding to matters described in the preceding embodiment will be assigned the same reference numerals, and duplicate descriptions may be omitted. In each embodiment, when only a part of the configuration is described, other previously described embodiments may be applied to the other parts of the configuration. In addition to combinations of parts that are specifically specified as being combinable in each embodiment, it is also possible to partially combine embodiments even if not specified, as long as there is no particular problem with the combination.

[0011] (First embodiment) The rotating machine according to this embodiment functions as a power source for rotating the propeller of an aircraft and is mounted on the aircraft. The aircraft in question is a vertical take-off and landing (eVTOL) electronic vertical take-off and landing aircraft. The propeller in question may be a propeller that generates flight thrust during vertical take-off and landing or hovering, or may be a propeller that generates flight thrust during cruising in horizontal flight.

[0012] 1 is a motor that is rotationally driven by a supply of three-phase AC power. The rotating machine 10 includes a housing 20, a stator 30, a rotor 40, a rotating shaft 50, bearings 60, a brush structure U, and the like.

[0013] The housing 20 is a metal enclosure that houses the stator 30 and the rotor 40. A pair of bearings 60 are attached to the housing 20. The bearings 60 hold the rotating shaft 50 in the housing 20 in a rotatable state.

[0014] The stator 30 has a stator core 31 and windings 32. The stator core 31 is configured by stacking multiple electromagnetic steel plates in the direction of the rotation axis. The direction of the rotation axis refers to the direction along the rotation center line C of the rotation axis 50. The windings 32 are wound around the stator core 31. The windings 32 are configured by star-connecting or delta-connecting a U-phase coil, a V-phase coil, and a W-phase coil. The on / off of current supply to each phase is controlled by a control device (not shown). The magnetic field generated by the current supply to the windings 32 is emitted to the outside of the stator 30 through the stator core 31. The emitted magnetic field rotates when the current supply to each phase coil is switched on and off. In this way, the stator 30 generates a rotating magnetic field.

[0015] The stator 30 is formed in a cylindrical shape surrounding the rotating shaft 50. The outer peripheral surface of the stator 30 and the inner peripheral surface of the housing 20 are tightly attached with resin 33. Metallic heat dissipation fins 21 are attached to the outer peripheral surface of the housing 20. The heat dissipation fins 21 are plate-shaped and extend in the rotational axis direction and the rotational diameter direction. The heat dissipation fins 21 are provided in at least the range of the rotational axis direction where the windings 32 are provided. A plurality of heat dissipation fins 21 are arranged in the circumferential direction. An air-cooling fan (not shown) is disposed at one axial end of the rotating machine 10. This air-cooling fan causes cooling air to flow in the rotational axis direction along the outer peripheral surface of the housing 20. This cooling air exchanges heat with the heat dissipation fins 21.

[0016] The windings 32 generate heat when current is applied. This heat raises the temperature of the stator 30, and ultimately the rotor 40 and the rotating shaft 50. Such a rise in temperature of the rotating machine 10 leads to a decrease in rotational output. In particular, an increase in the electrical resistance of the windings 32 leads to a decrease in rotational output. Therefore, in this embodiment, the resin 33 is used to tightly attach the windings 32 to the housing 20, thereby transferring the heat from the windings 32 to the stator 30 and dissipating the heat from the stator 30 through the heat dissipation fins 21. This suppresses a rise in temperature of the rotating machine 10.

[0017] The rotor 40 is disposed so as to provide an axial gap with respect to the stator 30. In this embodiment, the rotors 40 are disposed on both sides of the stator 30 in the direction of the rotation axis. The rotor 40 has a plurality of magnets 41 and a metallic rotor body 42.

[0018] 2, the magnets 41 are arranged at equal intervals in the circumferential direction of rotation. The surfaces of the magnets 41 that face the stator 30 are exposed from the rotor main body 42. The axial gap described above is formed between the exposed surfaces of the magnets 41 and the stator core 31.

[0019] The rotor body 42 has a disk shape and holds the magnet 41. A shaft hole 42a, through which the rotating shaft 50 is inserted, is formed in the center of the rotor body 42. An air gap 42g is formed between the inner circumferential surface of the shaft hole 42a and the outer circumferential surface of the rotating shaft 50 that faces the inner circumferential surface of the shaft hole 42a. A plurality of through holes 42b, through which bolts BT are inserted, are formed in the rotor body 42 around the shaft hole 42a. The plurality of through holes 42b are formed at equal intervals in the circumferential direction.

[0020] The rotating shaft 50 is made of metal and has a shaft main body portion 51 and a fastening portion 52. A portion of the shaft main body portion 51 is inserted into the shaft hole 42a. A portion of the shaft main body portion 51 is supported by a bearing 60. The fastening portion 52 extends radially from the shaft main body portion 51 and faces the rotor main body portion 42. A plurality of screw holes 52a are formed in the fastening portion 52 for fastening with bolts BT. By fastening with the bolts in this manner, the rotating shaft 50 is connected to the two rotors 40 and rotates integrally with the rotors 40.

[0021] The brush structure 70U is attached to the mounting portion 22 of the housing 20 and the rotating shaft. The mounting portion 22 is part of the housing 20 and is made of metal. The mounting portion 22 has a cylindrical shape extending in the direction of the rotating shaft. The brush structure 70U is attached between the inner circumferential surface of the mounting portion 22 and the outer circumferential surface of the shaft main body portion 51.

[0022] The brush structure 70U is in sliding contact with the rotating shaft 50 and is electrically connected to the housing 20, which serves as a grounding body. This provides electrical continuity between the rotating shaft 50 and the housing 20 (grounding body). The technical significance of the rotating machine 10 being provided with the brush structure 70U will be explained below with reference to FIG. 3.

[0023] The potential (shaft voltage) of the rotating shaft 50 may become high. High shaft voltages raise concerns about electrolytic corrosion of the bearings 60. In particular, the axial gap rotating machine 10 is prone to high shaft voltages. Specifically, as shown in FIG. 3 , the rotating machine 10 according to this embodiment has stray capacitances formed at multiple locations, which form voltage paths related to AC voltages. The main stray capacitances are described below. A stray capacitance C1 is formed between the winding 32 and the stator core 31. A stray capacitance C2 is formed between the stator core 31 and the rotor main body 42. A stray capacitance C3 is formed between the rotor main body 42 and the rotating shaft 50. A stray capacitance C4 is formed between the rotating shaft 50 and the bearing 60. The bearing 60 has the same potential as the grounded housing 20. Because the stray capacitances C1, C2, C3, and C4 form a series circuit, when the inverter voltage Vcom is applied to the winding 32, the potential (shaft voltage) of the rotating shaft 50 becomes higher than the ground voltage.

[0024] 3, the brush structure 70U functions as a resistor with one end electrically connected to the rotating shaft 50 and the other end electrically connected to the housing 20. The lower the resistance value of the brush structure 70U, the closer the shaft voltage can be to the ground voltage, thereby reducing concerns about bearing electrolytic corrosion and the like. Thus, the technical significance of the brush structure 70U is to reduce the shaft voltage and thereby reduce concerns about bearing electrolytic corrosion and the like.

[0025] Next, the structure of brush structure 70U will be described with reference to Figs. 4 to 7. Brush structure 70U includes brush 70, elastic body SP, inner ring 53, outer ring 80, and sealing materials 91 and 92. Fig. 4 is a view of brush structure 70U from the axial direction with sealing material 91 removed. Fig. 7 is a view of brush structure 70U from the axial direction with sealing material 91 and elastic body SP removed.

[0026] The inner ring 53 is a component of the brush structure 70U and is also a part of the rotating shaft 50. The inner ring 53 has a cylindrical shape and is fitted onto the outer peripheral surface of the rotating shaft 50. The inner ring 53 is made of metal. The inner ring 53 rotates integrally with the rotating shaft 50. The inner ring 53 may be fitted onto the rotating shaft 50 and fixed thereto, or may be fixed to the rotating shaft 50 by fastening a nut.

[0027] The brush 70 is made of resin containing conductive fibers (see FIG. 6). That is, the brush 70 has a fiber material 71 and a resin body 72. The fiber material 71 is a conductive fiber such as carbon fiber. The resin body 72 is formed by molding a resin containing a large amount of fiber material 71 into a block shape. For example, the content of fiber material 71 is 20%. A portion of the fiber material 71 is exposed from the surface of the resin body 72. In this embodiment, nylon is used as the material for the resin body 72.

[0028] As shown in FIG. 4, multiple brushes 70 are arranged in a line in the circumferential direction of the rotating shaft 50. The multiple brushes 70 are arranged at equal intervals in the circumferential direction. The multiple brushes 70 are packed together with no gaps in the circumferential direction. The resin body 72 has a shape that extends in an arc in the circumferential direction along the outer circumferential surface of the inner ring 53. An elastic body SP is pressed against the outer circumferential surface 72b of the resin body 72. The elastic force of the elastic body SP acts in a direction that presses the resin body 72 radially inward. Due to this elastic force, the inner circumferential surface 72a of the resin body 72 is pressed against the outer circumferential surface of the inner ring 53.

[0029] As shown in Fig. 5, the elastic body SP has a ring shape extending in the circumferential direction of the rotating shaft 50. The elastic body SP sandwiches a plurality of resin bodies 72 between itself and the rotating shaft 50. The elastic body SP also has a coil shape extending spirally around the central axis Csp. Since the central axis Csp extends annularly around the rotation center line C, the entire elastic body SP has a ring shape extending annularly around the rotation center line C.

[0030] The elastic body SP exerts an elastic force in a direction that reduces the diameter of the ring shape. In other words, the elastic body SP is in contact with the outer peripheral surfaces 72b of the multiple brushes 70 while elastically deforming in a direction that increases the diameter of the ring shape. As shown in FIG. 6, grooves 72c extending in the circumferential direction are formed in the outer peripheral surface 72b. The axial positions of the grooves 72c of each brush 70 are aligned. The inner ring-shaped portions of the elastic body SP are fitted into these grooves 72c. This fixes the axial position of the elastic body SP, preventing the elastic body SP from shifting in the axial direction.

[0031] The outer ring 80 has a cylindrical shape extending in the direction of the rotation axis. The outer ring 80 is fixed to the mounting portion 22 of the housing 20. This makes the outer ring 80 fixed so that it cannot rotate relative to the rotation axis 50. The outer ring 80 is made of resin. A plurality of protrusions 81 extending in the radial direction are formed on the inner peripheral surface of the outer ring 80. The outer ring 80 is made of resin, and the protrusions 81 are molded integrally with the outer ring 80 from resin.

[0032] 7, the multiple protrusions 81 are positioned between adjacent brushes 70 and come into contact with the brushes 70. As a result, the protrusions 81 restrict the rotation of the brushes 70 around the rotation center line C. In other words, the brushes 70 are engaged with the outer ring 80 to prevent rotation, and are pressed against the inner ring 53 by the elastic body SP. Therefore, when the winding 32 is energized to rotate the rotating shaft 50, the brushes 70 come into sliding contact with the outer peripheral surface of the inner ring 53.

[0033] The seal materials 91 and 92 are ring-shaped and extend in the circumferential direction of the rotating shaft 50. Ring outer diameter ends 91b and 92b of the seal materials 91 and 92 are attached to the outer ring 80. Ring inner diameter ends 91a and 92a of the seal materials 91 and 92 are in sliding contact with the inner ring 53 of the rotating shaft 50. The seal material 91 corresponds to a first seal material and covers the multiple brushes 70 from one side in the rotating shaft direction. The seal material 92 corresponds to a second seal material and covers the multiple brushes 70 from the other side in the rotating shaft direction.

[0034] 8 and 9, as wear of the brush 70 progresses, the radial dimension of the brush 70 decreases. In other words, the thickness of the brush 70 decreases. Even when the thickness of the brush 70 decreases, the brush 70 maintains a state in which it slides against the inner ring 53 due to its elastic force. Here, as shown in FIG. 4, the circumferential length Lout of the outer peripheral surface 72b of the resin body 72 is the same as the circumferential length Lin of the inner peripheral surface 72a.

[0035] <Action and effect> As described above, according to this embodiment, the rotating machine 10 includes brushes 70 and elastic bodies SP. The brushes 70 are in sliding contact with the rotating shaft 50 of the rotor 40 and are electrically connected to the housing 20 (grounded body), thereby electrically connecting the rotating shaft 50 and the housing 20. The elastic bodies SP press the brushes 70 against the rotating shaft 50. A plurality of brushes 70 are arranged in a line in the circumferential direction of the rotating shaft 50. Therefore, compared to a case in which only one brush 70 is provided, the electrical resistance at the contact portion between the brushes 70 and the rotating shaft 50 can be reduced without increasing the force (pressing force) pressing the brush 70 against the rotating shaft 50. This makes it possible to achieve both reduced electrical resistance and a longer brush life. This effect will be described below using test results shown in FIGS. 10 and 11.

[0036] The horizontal axis of FIG. 10 represents elapsed time, and the vertical axis represents the value of the shaft voltage. The inverter voltage Vcom applied from the inverter circuit to the winding 32 becomes a pulse with a period of 20 μs due to the switching operation of the inverter circuit. Reference numeral (1) in FIG. 10 represents the shaft voltage waveform of a rotating machine according to a comparative example in which the brush structure 70U is eliminated. Reference numeral (2) in FIG. 10 represents the shaft voltage waveform of the rotating machine 10 according to this embodiment, which is equipped with the brush structure 70U.

[0037] Here, the smaller the electrical resistance of the brush structure 70U, the smaller the axial voltage can be, and concerns about bearing electrolytic corrosion and the like can be reduced. To reduce the electrical resistance, the surface pressure of the brush 70 against the rotating shaft 50 can be increased. To increase the surface pressure, the contact area between the brush 70 and the inner ring 53 can be increased, or the pressing force can be strengthened. However, the higher the surface pressure, the more severe the brush wear and the shorter the brush life.

[0038] In the rotating machine 10 used in the test shown in Fig. 10, the surface pressure was set so that the electrical resistance of the brush structure 70U was 100 ohms. The test results shown in Fig. 10 show that the shaft voltage can be sufficiently reduced with an electrical resistance of 100 ohms. In other words, the surface pressure of 100 ohms is sufficient to reduce the shaft voltage.

[0039] The horizontal axis of Fig. 11 represents frequency, and the vertical axis represents impedance and phase of brush structure 70U. The test results in Fig. 11 are the impedance and phase of rotating machine 10 used in the test in Fig. 10, and show that the impedance is approximately 100 ohms and the phase is 0 to 20 degrees at all frequencies.

[0040] The horizontal axis of Fig. 12 represents surface pressure, and the vertical axis represents resistance of the brush structure 70U. Symbol (1) in Fig. 10 represents test results when nylon containing 20% ​​carbon fiber (conductive nylon) was used for the brush 70 according to this embodiment. Symbol (2) in Fig. 10 represents test results for the rotating machine 10 according to a comparative example in which a copper alloy was used for the brush.

[0041] As shown by symbol (1), with conductive nylon, the surface pressure can be reduced to 100 ohms even when it is reduced to P1. It was confirmed that the amount of wear can be sufficiently reduced at a surface pressure of P1. As shown by symbol (2), with copper alloy, the surface pressure can be reduced to 100 ohms even when it is reduced to P2, which is smaller than P1. However, it was confirmed that the amount of wear cannot be sufficiently reduced even at a surface pressure of P2.

[0042] As described above, the brush 70 of this embodiment is made of conductive nylon, which can sufficiently reduce the amount of wear and the shaft voltage compared to when a copper alloy is used.

[0043] Furthermore, in this embodiment, the brushes 70 are arranged at equal intervals around the circumference of the rotating shaft 50. Therefore, the pressing forces applied from the brushes 70 to the rotating shaft 50 are applied at equal intervals. This makes it possible to prevent a biased radial force from being applied to the bearing 60.

[0044] Furthermore, in this embodiment, the elastic body SP has a ring shape extending in the circumferential direction of the rotating shaft 50, and sandwiches the multiple brushes 70 between itself and the rotating shaft 50. Therefore, a pressing force can be applied to the multiple brushes 70 with a single elastic body SP, which simplifies the structure of the brush structure 70U.

[0045] Furthermore, in this embodiment, the elastic body SP has a coil shape that extends spirally around the central axis Csp, and the central axis Csp has a ring shape that extends in the circumferential direction of the rotation axis. This makes it easy to apply a pressing force to multiple brushes 70 with a single elastic body SP, thereby ensuring that the pressing force is evenly distributed among the brushes 70.

[0046] Furthermore, in this embodiment, an outer ring 80 is provided that is fixed so as not to rotate relative to the rotary shaft 50, and the brush 70 is engaged with the outer ring 80 to prevent rotation. Contrary to this embodiment, if the anti-rotation feature were eliminated, the elastic body SP would rotate together with the brush 70, which could cause damage to the brush structure 70U. In view of this, in this embodiment, the brush 70 is prevented from rotating, thereby alleviating the above-mentioned concern.

[0047] Furthermore, in this embodiment, the brush 70 has a conductive fiber material 71 and a resin body 72 containing the fiber material 71. The fiber material 71 is exposed from the surface of the resin body 72. This makes it possible to provide a brush 70 with improved abrasion resistance and conductivity, thereby promoting both reduced electrical resistance and a longer brush life.

[0048] Furthermore, in this embodiment, the circumferential length Lout of the outer circumferential surface 72b of the resin body 72 is the same as the circumferential length Lin of the inner circumferential surface 72a of the resin body 72. Therefore, the contact area between the brush 70 and the rotating shaft 50 is kept constant even as the brush 70 wears. Therefore, regardless of the degree of wear, the surface pressure can be kept constant, and the electrical resistance of the brush 70 can be kept constant. Furthermore, the circumferential distance between adjacent inner circumferential surfaces 72a of the multiple resin bodies 72 is kept constant even as the brush 70 wears. For example, when the multiple brushes 70 are arranged with no gaps in the circumferential direction, that is, when the above-mentioned gap distance is set to zero, the state of being arranged with no gaps can be maintained even as wear progresses.

[0049] Furthermore, in this embodiment, a ring-shaped seal member is provided that extends in the circumferential direction of the rotating shaft 50. An outer diameter end portion 91b of the seal member is attached to the outer ring 80, and an inner diameter end portion 91a of the ring is in sliding contact with the rotating shaft 50. The seal member includes a first seal member 91 that covers the multiple brushes 70 from one side in the direction of the rotating shaft, and a second seal member 92 that covers them from the other side. As a result, wear powder generated when the brushes 70 slide and wear is collected between the inner ring 53 and the outer ring 80. In other words, the seal members 91, 92 prevent the wear powder from leaking out of the brush structure 70U.

[0050] (Other embodiments) Although the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments or structures. The present disclosure also encompasses various modifications and modifications within the scope of equivalents. In addition, although various combinations and forms are shown in the present disclosure, other combinations and forms including only one element, more, or less are also within the scope and spirit of the present disclosure.

[0051] The brush 70 according to the first embodiment is made of a resin body 72 (e.g., conductive nylon) containing a conductive fiber material 71. Alternatively, a metal brush may be used. For example, a copper alloy or a bronze-based material is given as a specific example of the metal brush.

[0052] In the first embodiment, the number of brushes 70 included in the brush structure 70U is 12, but the number may be any number, such as 2 or 3. The brushes 70 are preferably arranged at equal intervals, but do not have to be arranged at equal intervals.

[0053] The elastic body SP according to the first embodiment is ring-shaped, and the number of elastic bodies SP is reduced to one by sandwiching multiple brushes 70 between the elastic body SP and the rotary shaft 50. Alternatively, a separate elastic body SP may be provided for each brush 70, and each elastic body SP may apply a pressing force to the brush 70.

[0054] In the brush 70 according to the first embodiment, the circumferential length Lout of the outer peripheral surface 72b of the resin body 72 is the same as the circumferential length Lin of the inner peripheral surface 72a of the resin body 72. However, the outer peripheral surface 72b may be longer or shorter than the inner peripheral surface 72a. Furthermore, the multiple brushes 70 according to the first embodiment are arranged with no gaps in the circumferential direction. However, the brushes 70 may be arranged so that there is a gap between adjacent brushes 70.

[0055] The brush structure 70U according to the first embodiment has the sealing materials 91 and 92, but at least one of these sealing materials 91 and 92 may be eliminated.

[0056] The rotating machine 10 according to each of the above embodiments is a double axial gap motor in which two rotors 40 are provided for one stator 30. In contrast, the rotating machine 10 may have a structure in which one rotor 40 is provided for one stator 30, or a structure in which one rotor 40 is provided for two stators 30. Furthermore, although the rotor 40 described above generates a field magnet with the magnet 41, the rotor 40 may have a structure in which a field winding is provided instead of the magnet 41.

[0057] The rotating machine 10 is not limited to being used for propeller power in an aircraft, but may also be used as a running power source mounted on a vehicle, or as a stationary motor or generator. [Explanation of symbols]

[0058] 10 Rotating machine, 20 Housing (earthed body), 30 Stator, 32 Winding, 40 Rotor, 50 Rotating shaft, 70 Brush, 71 Fiber material, 72 Resin body, 72a Inner surface, 72b Outer surface, 80 Outer ring, 91 First seal material, 92 Second seal material, Lin Circumferential length of inner surface, Lout Circumferential length of outer surface, SP Elastic body.

Claims

1. a stator (30) that generates a rotating magnetic field when current is applied to a winding (32); a rotor (40) that rotates due to the rotating magnetic field; a rotating shaft (50) connected to the rotor; a brush (70) that is in sliding contact with the rotating shaft and is electrically connected to a grounding body (20), thereby electrically conducting the rotating shaft and the grounding body; an elastic body (SP) that presses the brush against the rotary shaft; Equipped with A rotating machine in which a plurality of the brushes are arranged in a line in the circumferential direction of the rotating shaft.

2. The rotary machine according to claim 1 , wherein a plurality of said brushes are arranged at equal intervals in the circumferential direction of said rotary shaft.

3. 3. The rotating machine according to claim 1, wherein the elastic body has a ring shape extending in a circumferential direction of the rotary shaft, and sandwiches the plurality of brushes between the elastic body and the rotary shaft.

4. 4. The rotating machine according to claim 3, wherein the elastic body has a coil shape that extends spirally around a central axis, and the central axis has a ring shape that extends in a circumferential direction of the rotating shaft.

5. An outer ring (80) is provided which is fixed to the rotation shaft so as not to be rotatable relative to the rotation shaft, 3. The rotating machine according to claim 1, wherein the brush is engaged with the outer ring to prevent rotation.

6. The brush has a conductive fiber material (71) and a resin body (72) containing the fiber material, The rotating machine according to claim 1 or 2, wherein the fibrous material is exposed from a surface of the resin body.

7. the resin body has an inner circumferential surface (72a) pressed against the rotating shaft and an outer circumferential surface (72b) pressed against by the elastic body, The rotating machine according to claim 6, wherein a circumferential length (Lout) of the outer circumferential surface is the same as a circumferential length (Lin) of the inner circumferential surface.

8. an outer ring (80) fixed to the rotation shaft so as not to be rotatable relative to the rotation shaft; a ring-shaped seal member extending in a circumferential direction of the rotating shaft, with an outer diameter end of the ring attached to the outer ring and an inner diameter end of the ring in sliding contact with the rotating shaft; Equipped with 3. The rotating machine according to claim 1, wherein the sealing material includes a first sealing material (91) that covers the plurality of brushes from one side in the axial direction of the rotating shaft, and a second sealing material (92) that covers the plurality of brushes from the other side in the axial direction of the rotating shaft.

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