Rotating electrical machine

Abstract

This rotating electrical machine comprises: a housing having a first cover through which a rotor shaft penetrates; a brush holder holding a brush; a brush-holder housing part recessed in an axial direction from the outside of the first cover and housing the brush holder; and a second cover covering the brush-holder housing part. The brush holder includes: a through-hole through which the rotor shaft penetrates; and a wall projecting in the axial direction of the rotor shaft, along at least part of the outer edge of the through-hole. The wall includes, in at least part of an area at a position opposing an electrode provided to the rotor shaft, at least one projecting section that projects toward the axis of rotation of the rotor shaft.

Description

Rotating electric machines

[0001] The present invention relates to a rotating electric machine.

[0002] In rotating electrical machines having brushes for supplying power to the rotor, wear particles are generated due to wear between the brushes and electrodes attached to the rotor shaft. When such wear particles accumulate, they become conductive foreign matter and may cause a short circuit between adjacent electrodes. JP2871003B discloses a rotating electrical machine in which a recess is formed on the side of the brush, and the brush is worn down to the recess by the commutator, so that the wear particles that have grown on the end of the brush side are worn away by the rotation of the rotor shaft.

[0003] However, the configuration described in the above document does not take into consideration fibrous conductive foreign matter that may grow on the surface of the electrode fixed to the rotor shaft, which may result in a short circuit caused by the grown fibrous conductive foreign matter, i.e., a deterioration in insulation.

[0004] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a rotating electrical machine that can suppress the deterioration of insulation due to the above-mentioned conductive foreign matter.

[0005] According to one aspect of the present invention, there is provided a rotating electric machine comprising: a housing having a first cover through which a rotor shaft passes, a brush holder for holding a brush, a brush holder accommodating portion axially recessed from the outside of the first cover and accommodating the brush holder, and a second cover covering the brush holder accommodating portion. In this rotating electric machine, the brush holder comprises a through hole through which the rotor shaft passes, and a wall that protrudes in the axial direction of the rotor shaft along at least a portion of the outer edge of the through hole, and the wall comprises at least one protrusion that protrudes toward the rotation axis of the rotor shaft at least in a portion of a position facing an electrode provided on the rotor shaft.

[0006] FIG. 1 is an explanatory diagram of a drive unit including a rotating electric machine, as viewed from the axial side. FIG. 2 is a diagram of the drive unit of FIG. 1 with a second cover and a bus bar cover attached. FIG. 3 is an explanatory diagram of the first cover, focusing on a brush holder accommodating portion. FIG. 4 is a cross-sectional view showing the positional relationship between a rotor shaft, a slip ring, and a brush. FIG. 5 is a perspective view of a brush holder. FIG. 6 is a cross-sectional view of the vicinity of a through hole of the brush holder, as viewed in the axial direction. FIG. 7 shows the rotor shaft, a wall, and a protrusion extracted from FIG. 6. FIG. 8 is a cross-sectional view of the vicinity of a through hole of a brush holder according to a modified example, as viewed in the axial direction.

[0007] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0008] Fig. 1 is an explanatory diagram of a drive unit 100 including a rotating electric machine 1 according to this embodiment, as viewed from the axial side. Fig. 2 is an explanatory diagram of the drive unit 100, showing a state in which a second cover 22 and a bus bar cover 26 are attached.

[0009] The drive unit 100 is composed of a rotating electric machine 1 and an inverter unit 3 that supplies power to the rotating electric machine 1. The inverter unit 3 is mounted on top of the rotating electric machine 1.

[0010] The rotating electric machine 1 is configured by housing a rotor and a stator (not shown) housed in a housing 2. The rotor includes a rotor shaft 11. The housing 2 includes a refrigerant flow path through which a refrigerant (cooling oil) for cooling circulates, and a refrigerant inlet 2a and a refrigerant outlet 2b through which the refrigerant flows in and out of the housing 2.

[0011] The rotating electric machine 1 is mounted on a vehicle and functions as an electric motor that drives the wheels. The rotating electric machine 1 also functions as a generator that generates electricity (regenerative) by receiving driving force from the rotation of the wheels. The rotating electric machine 1 is configured as a wound-field type electric motor.

[0012] The housing 2 has an internal cavity with an opening, and the stator and rotor are housed in the internal cavity. The opening, which opens on the axial side of the housing 2 (the front side in FIG. 1 ), is covered with a first cover 21. A second cover 22 and a bus bar cover 26 are attached to the outside of the first cover 21. The rotor shaft 11 protrudes to the outside from the first cover 21 and rotatably supports the rotor shaft 11. The housing 2, first cover 21, second cover 22, and bus bar cover 26 are formed by casting using a metal material such as an aluminum alloy.

[0013] A slip ring 12 is provided on the outer periphery of the rotor shaft 11. Brushes 5 abut against the slip ring 12, and the inverter unit 3 and a field winding provided on the rotor are electrically connected via the brushes 5, so that DC power from the inverter unit 3 is supplied to the field winding.

[0014] The brushes 5 are housed in the brush holders 15 and held by the brush holders 15 , and are fixed to the rotor shaft 11 .

[0015] FIG. 3 is an explanatory diagram of the first cover 21 with the brush holder housing portion 20 at the center.

[0016] The first cover 21 has a brush holder accommodating portion 20 that accommodates the brush holder 15. The brush holder accommodating portion 20 is formed in a concave shape that is recessed from the side surface of the first cover 21 (the outermost surface of the first cover 21) toward the back in the axial direction. The brush holder accommodating portion 20 is formed in a shape that is slightly larger than the outer peripheral shape of the brush holder 15.

[0017] The brush holder 15 is a case made of insulating resin that houses and holds multiple brushes 5 inside. The brush holder 15 has a through hole 16 through which the rotor shaft 11 passes, and a wall 30 that extends along at least a portion of the outer edge of the through hole 16 and protrudes in the axial direction of the rotor shaft 11. The wall 30 has at least one protrusion 31 that protrudes toward the rotation axis of the rotor shaft 11 at least in a portion of a position facing an electrode provided on the rotor shaft 11. The wall 30 and the protrusion 31 will be described later.

[0018] The brush 5 and the wall 30 are arranged side by side in the circumferential direction around the rotation axis of the rotor shaft 11 .

[0019] The rotor shaft 11 is provided with slip rings 12 as two electrodes, positive and negative, arranged in parallel at positions spaced apart in the axial direction.

[0020] The brush holder 15 has a pair of brushes 5 for each of the positive and negative slip rings 12. The brushes 5 have a square rod shape, and one longitudinal end thereof abuts against the slip rings 12 of the rotor shaft 11. A biasing member such as a spring is disposed on the other longitudinal end of the brush 5, and the brush 5 is pressed against the slip ring 12.

[0021] A pair of brushes 5 fixed to a brush holder 15 abuts against the positive or negative slip ring 12. The angle between the longitudinal axes of the pair of brushes 5 is an acute angle. That is, the pair of brushes 5 are arranged in a V-shape so that they move apart as they move away from the slip ring 12. Note that, as will be described later, if the brush holder 15 is arranged offset to one side of the rotor shaft 11, the brushes 5 do not necessarily have to be arranged in a V-shape at an acute angle.

[0022] The brush holder 15 is fixed to the side surface of the brush holder accommodating portion 20 by three bolts 151 .

[0023] In the first cover 21, the brush holder accommodating portion 20 communicates with a communicating portion 23 formed at its upper portion in an axially shallow manner. The communicating portion 23 further communicates with a connecting portion 24 formed at its upper portion in an axially recessed manner. The connecting portion 24 accommodates the tip of a field bus bar 241 to which DC power from the inverter unit 3 is supplied. Wiring 19 is connected between the field bus bar 241 and the brush holder 15. The wiring 19 is routed in the vertical direction from the connecting portion 24 to the brush holder accommodating portion 20 via the communicating portion 23. Ends of the wiring 19 are connected to the brushes 5, respectively.

[0024] As shown in FIG. 2, a second cover 22 is attached to the brush holder accommodating portion 20, the communication portion 23 and the connection portion 24 recessed in the first cover 21 to close them from the outside.

[0025] A busbar accommodating portion 25 is recessed in the axial direction above the brush holder accommodating portion 20 and to the side of the connecting portion 24. The busbar accommodating portion 25 accommodates the tips of three-phase busbars 41 for supplying three-phase power to the inverter unit 3. As shown in FIG. 2 , a busbar cover 26 is attached to the busbar accommodating portion 25 to close the recess of the busbar accommodating portion 25 from the outside.

[0026] 4 is a cross-sectional view showing the positional relationship between the rotor shaft 11, slip ring 12, and brushes 5. Positive and negative electrodes (12(+) and 12(-) in the figure) are arranged axially spaced apart on the rotor shaft 11. A pair of brushes 5 is arranged in a V-shape for each electrode, as shown in FIG.

[0027] That is, when viewed in the axial direction of the rotor shaft 11, the wall 30 is provided at a position that does not overlap with the position where the brush 5 is disposed.

[0028] In the rotating electric machine 1 configured as described above, the brushes 5 are pressed against the electrodes provided on the slip rings 12. Therefore, when the rotor shaft 11 rotates, the brushes 5 rub against the electrodes, which may cause fibrous chips (hereinafter also referred to as conductive foreign matter) to form on the electrode surfaces. These chips may then short-circuit the positive and negative electrodes.

[0029] The structure for preventing short circuits caused by the conductive foreign matter will be described below with reference to Figures 1, 3, and 5-6. Figure 5 is a perspective view of the brush holder 15. Figure 6 is a cross-sectional view of the brush holder 15 near the through-hole 16 as viewed in the axial direction.

[0030] As described above, the brush holder 15 includes a wall 30 that extends along at least a portion of the outer edge of the through hole 16 and protrudes in the axial direction of the rotor shaft 11. In this embodiment, the wall 30 is provided on the outer edge of the rotor shaft 11 on the side facing the brush 5.

[0031] Furthermore, as described above, the wall 30 is provided with at least one protrusion 31 that protrudes toward the rotation axis of the rotor shaft 11 at least in a portion of the position facing the electrode provided on the rotor shaft 11. In this embodiment, a plurality of protrusions 31 are provided.

[0032] Here, the protrusion 31 will be described. In the following description, the rotation direction when the vehicle moves forward is referred to as the forward direction, and the rotation direction when the vehicle moves backward is referred to as the reverse direction (see the arrows in the figure). The end of the protrusion 31 on the wall 30 side is referred to as the base end, and the end on the rotation axis side of the rotor shaft 11 is referred to as the tip end. Note that the base end here refers to the center of the portion of the protrusion 31 that contacts the wall 30. For example, as shown in Figure 6, if the cross-sectional shape of the protrusion 31 when viewed in the axial direction is a substantial triangle with the base on the wall 30 side, the center of the base is referred to as the base end.

[0033] At this time, the tip of the protrusion 31 is offset in the reverse rotation direction from the straight line (dashed line in FIG. 6 ) connecting the base end and the rotation axis C of the rotor shaft 11. In other words, the protrusion 31 is inclined in the reverse rotation direction from the straight line connecting the base end and the rotation axis C.

[0034] The effect of providing the protrusions 31 as described above will be described with reference to Fig. 7. Fig. 7 shows the rotor shaft 11, the wall 30, and the protrusions 31 extracted from Fig. 6.

[0035] When the rotor shaft 11 rotates, the slip ring 12 rubs against the brush 5, causing conductive foreign matter 12A to be generated on the outer circumferential surface of the slip ring 12. When the rotor shaft 11 rotates forward, there is a high probability that the conductive foreign matter 12A will peel off from the surface of the slip ring 12, with the end of the conductive foreign matter 12A on the reverse rotation side remaining connected to the slip ring 12, as shown in FIG.

[0036] When the rotor shaft 11 rotates with such conductive foreign object 12A generated, the vicinity of the tip of the conductive foreign object 12A becomes caught between the protrusion 31 and the wall 30. Then, as the rotor shaft 11 continues to rotate with the vicinity of the tip of the conductive foreign object 12A caught on the protrusion 31, the conductive foreign object 12A is torn off from the rotor shaft 11. Even if the conductive foreign object 12A does not get caught on the first protrusion 31, if there are multiple protrusions 31 in the direction of rotation, there is a possibility that the conductive foreign object 12A will get caught on one of the protrusions 31. In other words, at least one protrusion 31 is sufficient, but if there are multiple protrusions 31, the possibility of removing the conductive foreign object 12A increases.

[0037] Experiments have shown that the possibility of removing conductive foreign matter 12A is high when the angle formed between the side surface of protrusion 31 on the reverse direction side and wall 30 and the tangent to wall 30 at the point of contact with this side surface, i.e., the angle θ formed by the two-dot chain line and the one-dot chain line in Figure 7, is approximately 30 to 45 degrees, and is particularly high when it is 30 degrees. This is thought to be because the larger the angle θ, the more difficult it is to generate resistance sufficient to remove conductive foreign matter 12A, even if the tip of conductive foreign matter 12A gets between the side surface of protrusion 31 on the reverse direction side and wall 30.

[0038] [Modification] Next, a modification of the above embodiment will be described with reference to Fig. 8. This modification, like the above embodiment, also falls within the scope of the present invention.

[0039] FIG. 8 is a cross-sectional view of the vicinity of the through-hole 16 of the brush holder 15 according to a modified example, viewed in the axial direction.

[0040] In this modification, the protrusion 31 described in the above embodiment is referred to as a forward rotation protrusion 31 A. The difference between this modification and the above embodiment is that the brush holder 15 of this modification includes not only the forward rotation protrusion 31 A but also a reverse rotation protrusion 31 B.

[0041] The reverse rotation protrusion 31B has a symmetrical shape to the forward rotation protrusion 31A. That is, the tip is offset toward the forward rotation direction with respect to the straight line (dashed line in FIG. 6 ) connecting the rotation axis C and the base end of the rotor shaft 11. In other words, the reverse rotation protrusion 31B is inclined in the forward rotation direction with respect to the straight line connecting the rotation axis C and the base end.

[0042] By providing the reverse rotation protrusion 31B as described above, conductive foreign matter 12A that occurs when the rotor shaft 11 rotates in the reverse direction (i.e., when the vehicle moves backward) can be removed in the same way as when the rotor shaft 11 rotates in the forward direction.

[0043] Furthermore, the number of forward rotation projections 31A is greater than the number of reverse rotation projections 31B. This is because, when the rotating electric machine 1 is used as a drive device for a vehicle, forward rotation occurs more frequently than reverse rotation, and therefore emphasis is placed on removing conductive foreign matter 12A that occurs during forward rotation.

[0044] As described above, according to this embodiment, a rotating electric machine 1 is provided, which includes a housing 2 having a first cover 21 through which the rotor shaft 11 passes, a brush holder 15 that holds a brush 5, a brush holder accommodating portion 20 that is axially recessed from the outside of the first cover 21 and accommodates the brush holder 15, and a second cover 22 that covers the brush holder accommodating portion 20. In this rotating electric machine 1, the brush holder 15 includes a through hole 16 through which the rotor shaft 11 passes, and a wall 30 that protrudes in the axial direction of the rotor shaft 11 along at least a portion of the outer edge of the through hole 16. The wall 30 includes at least one protrusion 31 that protrudes toward the rotation axis of the rotor shaft 11 at at least a portion of a position facing an electrode (slip ring 12) provided on the rotor shaft 11. With this configuration, conductive foreign matter 12A occurring on the surface of the electrode is caught by the protrusion 31 as the rotor shaft 11 rotates, and is broken by being compressed or pulled, and is removed from the electrode. That is, it is possible to prevent the conductive foreign matter 12A from growing and causing a short circuit with another electrode or a ground fault.

[0045] In this embodiment, the brush 5 and the wall 30 are arranged side by side in the circumferential direction around the rotation axis of the rotor shaft 11. This allows the protrusions 31 provided on the wall 30 to remove conductive foreign matter 12A that occurs on the surface of the electrode 12 due to friction with the brush 5.

[0046] In this embodiment, rotor shaft 11 is provided with a plurality of electrodes (slip rings 12) at positions spaced apart in the axial direction, and brush holder 15 has a pair of brushes 5 arranged in a V-shape for one electrode, and another pair of brushes arranged in a V-shape for another electrode, and walls 30 are provided at positions that do not overlap with the positions of the brushes when viewed axially of rotor shaft 11. With this configuration, even if conductive foreign matter 12A is generated when the brushes pass, the conductive foreign matter 12A is removed by protrusions 31, and therefore, the conductive foreign matter 12A can be prevented from growing due to repeated friction with the brushes.

[0047] In this embodiment, the rotating electric machine 1 is used as a drive device for a vehicle, and the rotation direction when the vehicle moves forward is defined as the forward direction, and the rotation direction when the vehicle moves backward is defined as the reverse direction. The end of the protrusion 31 on the wall 30 side is defined as the base end, and the end on the rotation axis side of the rotor shaft 11 is defined as the tip end. In this case, the tip end of the protrusion 31 is offset toward the reverse direction with respect to a line connecting the rotation axis of the rotor shaft 11 and the base end. This makes it easier for conductive foreign matter 12A occurring on the surface of the electrode (slip ring 12) to be caught by the protrusion 31.

[0048] In this modified example, a plurality of protrusions 31 are provided, some of which are forward rotation protrusions 31A, and the others are reverse rotation protrusions 31B whose tips are offset toward the forward rotation direction with respect to a line connecting the rotation axis and the base end of the rotor shaft 11. This makes it possible to remove conductive foreign matter 12A that occurs when the vehicle is reversed.

[0049] In this modification, the number of forward rotation protrusions 31A is greater than the number of reverse rotation protrusions 31B. This increases the possibility of removing conductive foreign matter 12A during forward rotation, which is the most frequently used time, while also making it possible to remove conductive foreign matter 12A during reverse rotation.

[0050] Although the embodiments of the present invention have been described above, the above embodiments merely illustrate some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above embodiments.

Claims

1. A housing having a first cover through which the rotor shaft passes, A brush holder that holds the brush, A brush holder housing portion is recessed in the axial direction from the outside of the first cover and houses the brush holder, A second cover that covers the brush holder housing portion, In a rotating electric machine equipped with, The brush holder comprises a through hole through which the rotor shaft passes, and a wall that extends along a portion of the outer edge of the through hole on the side facing the brush across the rotor shaft and protrudes in the axial direction of the rotor shaft, Equipped with, A rotating electric machine wherein the wall has at least one projection that protrudes toward the rotation axis of the rotor shaft at least a portion of the position facing the electrode provided on the rotor shaft.

2. In the rotating electric machine described in claim 1, A rotating electric machine in which the brush and the wall are arranged in a circumferential direction with respect to the rotation axis of the rotor shaft.

3. In the rotating electric machine according to claim 2, The rotor shaft is provided with a plurality of electrodes spaced apart in the axial direction. In the brush holder, one pair of brushes is arranged in a V-shape with respect to one electrode, and another pair of brushes is arranged in a V-shape with respect to the other electrode. A rotating electric machine in which the wall is provided in a position that does not overlap with the position where the brush is arranged when viewed in the axial direction of the rotor shaft.

4. In the rotating electric machine described in claim 1, Used as a vehicle drive system, When a vehicle moves forward, the direction of rotation is defined as the forward direction, and when it moves backward, the direction of rotation is defined as the reverse direction. When the wall-side end of the projection is considered the base end and the rotor shaft-side end is considered the tip, The aforementioned projection is a forward-rotating projection whose tip is offset in the reverse direction with respect to the straight line connecting the rotation axis of the rotor shaft and the base end, in a rotating electric machine.

5. In the rotating electric machine according to claim 4, The aforementioned protrusions are provided in multiple locations. A rotating electric machine in which some of the multiple projections are forward rotation projections, and the other parts are reverse rotation projections whose tips are offset toward the forward rotation direction with respect to the straight line connecting the rotation axis of the rotor shaft and the base end.

6. In the rotating electric machine according to claim 5, A rotating electric machine in which the number of forward rotation protrusions is greater than the number of reverse rotation protrusions.