JP2010166747A - Brush unit of rotating electric machine and rotating electric machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent brush wear in a motor using a disk commutator. <P>SOLUTION: A brush member 50 slidably contacting a plurality of sectorial conductor sections 36 radially arranged on the disk commutator 32 is formed so that its sliding surface becomes rectangular, and brushes are arranged so that both long sides of the rectangle become parallel to the diameter of the disk commutator. Since the brush unit is formed in a shape having edges slanting to the boundary line of the plurality of conductor sections, switching to a subsequent conductor section is gradually executed in the brush. Thus, rectification is good and spark at sudden switching is suppressed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a brush device for a rotating electrical machine using a disk commutator.

  2. Description of the Related Art Conventionally, as a power supply device for an electric motor, a brush including a disk-shaped disk commutator that is attached to an end portion in the axial direction of a rotor and rotates integrally with the rotor, and a brush member that is fixedly disposed on the motor housing side and slidably contacts the disk commutator There are those depending on the device (for example, Patent Documents 1 and 2).

JP 2003-324908 A JP 2004-304946 A

  In the brush device described above, as shown in FIG. 8, a plurality of fan-shaped segments 36 constituting the disk commutator 32 are arranged radially on the disk surface, and the brush 60 is provided in each segment 36 on the disk surface. Are slid sequentially. The shape of the sliding contact surface of the brush 60 in such a disc commutator 32 is formed in a trapezoidal shape in a plan view as seen from the axial direction (front and back direction in the drawing) of the disc commutator 32 as shown in the figure. However, when the segment 36 is switched across the border 36a formed by the gap between the segments 36 and the segment 36 is switched, there is a positive / negative switching of the current, and when the switching change is large, a spark is generated, thereby causing wear of the brush 60. There is a problem that becomes faster.

  In order to reduce brush wear, brush motors equipped with a cylindrical surface commutator take the contact surface of the brush as wide as possible to reduce the brush current density. However, if the disk commutator is expanded radially outward in order to make the contact surface of the brush as wide as possible, there is a limitation due to restrictions on the outside of the disk commutator. Further, when the disk commutator is expanded in the circumferential direction (width direction), the contact number of the brush cannot be widened because the number of conductors is restricted. That is, there is a limit in increasing the sliding surface of the brush in the case where the fan-shaped segments are arranged radially like the disk commutator.

  In order to solve such problems and realize that in a rotating electric machine using a disk commutator, it is possible to suppress the wear of the brush, in the present invention, the segments made of fan-shaped conductors are radially formed on a plane. A brush device of a rotating electrical machine having a brush that is in sliding contact with the plurality of segments of the disposed disk commutator, wherein at least one edge of the front side and the rear side in the sliding contact direction of the sliding contact surface of the brush, It was formed so as to be skewed with respect to the boundary line on the boundary line dividing the plurality of segments.

  In particular, the sliding surface is provided with a recess, and the recess is preferably provided in the center of the sliding surface with respect to the sliding contact direction, and the sliding surface is formed in a rectangular shape. Good to be. Moreover, it is good in the rotary electric machine which has the brush apparatus of the rotary electric machine of the said structure, the housing to which the said brush apparatus is fixed, and the rotor rotatably supported by the said housing.

  As described above, according to the present invention, since the shape of the brush in the disk commutator is formed to have a shape having an oblique line with respect to the boundary lines of the plurality of segments, the switching to the next segment in the brush is gradually performed. Since it is carried out, the rectification is good and it is possible to suppress the occurrence of sparks that occur when switching at a stroke.

  Further, in the conventional brush shape, one end of the slidable contact surface of the brush is in contact with the disk commutator, but the other end of the slidable contact surface of the brush may not be in contact with the disk commutator. On the other hand, like the brush of the present invention, the contact pressure can be applied in a balanced manner to both ends of the sliding surface of the brush by forming a recess on the sliding surface of the brush. Furthermore, by forming the groove in the center with respect to the sliding contact surface of the brush, a pressure higher than the contact pressure of the normal-shaped brush can be applied to both ends of the brush in a balanced manner. As a result, high contact pressure can be generated at both ends of the brush, and both ends of the brush are in sliding contact with the disk commutator, so that the motor characteristics are stabilized even in the initial stage of use of the motor.

  In addition, since the sliding contact surface is rectangular, the brush can be formed in a rectangular parallelepiped, which facilitates processing, and at the beginning and end of switching to the next segment for the fan-shaped segment in the disk commutator. Thus, it is possible to easily switch gradually at both portions, and to further improve the rectification. Further, by providing the rotating electrical machine with the brush device of the rotating electrical machine configured as described above, it is possible to improve the brush wear resistance of the rotating electrical machine using the disk commutator.

It is a figure showing the whole electric motor composition of this embodiment. It is a figure which shows the disk commutator and brush seen along the arrow II-II line | wire of FIG. (A) is a figure which shows the change of the contact area of a brush with respect to the rotation angle of a disk commutator, (b) is a figure which shows the change of contact resistance. It is a figure which shows a rectification curve. (A) is a figure which shows the change of the contact area of the brush with respect to the rotation angle of the conventional disc commutator, (b) is a figure which shows the change of contact resistance. It is principal part sectional drawing of the brush seen along the arrow VI-VI line of FIG. (A) is a figure which shows another shape of a brush, (b) is a figure which shows another shape of a brush. It is a figure which shows the conventional disc commutator and a brush.

  FIG. 1 shows the overall configuration of a starter motor M according to the first embodiment. The starter motor M includes a motor housing (housing) 16 fixed to an engine (not shown) of the vehicle, and a rotor 30 that is rotatably supported by the motor housing 16. The motor housing 16 includes a cylindrical yoke 10 having a plurality of permanent magnets 18, a rear bracket 14 that is fixed to one opening peripheral edge portion 10 a of the yoke 10, a power feeding portion E and a brush device 40, and the yoke 10. And a front bracket 12 fixed to the other opening peripheral edge portion 10b.

  The rotor 30 includes a coil 28 that is electrically connected to the power feeding unit E via the brush device 40, and is disposed inside the motor housing 16 so as to face the permanent magnet 18. Therefore, when a current is supplied from the power supply unit E to the coil 28 via the brush device 40, the rotor 30 is excited. That is, when a current is supplied to the coil 28, a force is generated in the circumferential direction of the rotor 30, the rotor 30 rotates, and the engine is driven.

  The rotor 30 includes a rotor core 26, a disk commutator 32, and a shaft 24 into which the rotor core 26 and the disk commutator 32 are press-fitted. One end 24 a of the shaft 24 of the rotor 30 is inserted into the oilless metal 22 press-fitted into the rear bracket 14, and the other end 24 b of the shaft 24 of the rotor 30 is press-fitted into the front bracket 12. Inserted into the bearing 20.

  A rotor core 26 and a disk commutator 32 are press-fitted into the shaft 24 of the rotor 30, and the rotor 30 is rotatably supported by the motor housing 16. A gear 24c is formed at the other end 24b of the shaft 24, and meshes with an engine gear (not shown). Therefore, the engine is driven as the rotor 30 rotates.

  The rotor core 26 press-fitted into the shaft 24 is formed by laminating a plurality of core plates made of a magnetic material, and has a T-shaped tooth portion 120. In the first embodiment, the rotor core 26 has 32 tooth portions 120 in order to improve rectification. However, in order to improve the rectification property, the rotor core 26 only needs to have 25 to 35 teeth portions 120.

  The laminated rotor core 26 is covered with a coating material in order to ensure insulation. A coil 28 is wound around the teeth portion 120 of the rotor core 26 covered with the coating material, and the coil 28 is fixed to the rotor core 26 with the coating material. Therefore, there is no fear that the coils 28 are in contact with each other, and the insulation of the coil 28 is ensured. In addition, in order to improve the rectification property of the starting motor M, the coil 28 is wound around the tooth portion 120 of the rotor core 26 with a short-pitch winding.

  The disk commutator 32 press-fitted into the shaft 24 rotates integrally with the rotor 30. The disk commutator 32 has a plurality of fan-shaped conductive portions (segments) 36, and the insulating base member 34 formed in a disk shape includes the conductive portions 36 formed in a fan shape and is insert-molded. ing. The coil 28 is connected to the disk commutator 32 by fusing. For this reason, the disk commutator 32 is electrically connected to the coil 28 wound around the rotor core 26.

  The motor housing 16 includes a yoke 10 formed in a cylindrical shape, a rear bracket 14 that fits in one opening peripheral portion 10a of the yoke 10, and a front bracket that fits in another opening peripheral portion 10b of the yoke 10. 12. The starting electric motor M is fixed to the engine by a bolt (not shown) or the like via a leg portion 14k formed on the rear bracket 14.

  The yoke 10 is formed in a cylindrical shape by a magnetic material such as iron, and a plurality of permanent magnets 18 are alternately arranged on the yoke 10 with magnetic poles. One opening peripheral edge portion 10a of the yoke 10 is inlay-fitted with the rear bracket 14, and the other opening peripheral edge portion 10b of the yoke 10 is inlay-fitted with the front bracket 12. Therefore, the opening peripheral portions 10a and 10b of the yoke 10 are formed thin.

  Bolts 114 are inserted into the front bracket 12 that is inlay-fitted to the other opening peripheral edge portion 10 b of the yoke 10. The bolt 114 is screwed into a bolt hole (not shown) formed in the rear bracket 14 via the yoke 10. That is, the yoke 10, the rear bracket 14, and the front bracket 12 are integrated by the bolts 114 to constitute the starter motor M. A rubber-made square ring 116 is disposed between one opening peripheral portion 10a of the yoke 10 and the opening peripheral portion 14a of the rear bracket 14, and the other opening peripheral portion 10b of the yoke 10 and the front bracket. A rubber square ring 116 is disposed between the twelve opening peripheral edges 12a. That is, the square ring 116 seals between the yoke 10 and the rear bracket 14, and seals between the yoke 10 and the front bracket 12. Therefore, water or the like does not enter the motor housing 16 from the outside.

  The front bracket 12 is formed in a bowl shape by aluminum die-casting, and is fitted in-slot with one opening peripheral edge portion 10 b of the yoke 10. Therefore, the opening peripheral edge portion 12a of the front bracket 12 is formed thin. The front bracket 12 is formed with a cylindrical boss portion 12b, and an O-ring 112 is fixed to the boss portion 12b. Therefore, the starting electric motor M attached to the engine is sealed by the O-ring 112.

  A bearing 20 and an oil seal 109 are press-fitted into the front bracket 12. Therefore, engine oil does not enter the motor housing 16. The other end 24 b of the shaft 24 of the rotor 30 is inserted into the bearing 20 press-fitted into the front bracket 12. Therefore, the rotor 30 is rotatably supported by the front bracket 12.

  The rear bracket 14 is formed in a bowl shape by aluminum die-casting, and is inlay-fitted with one opening peripheral edge portion 10 a of the yoke 10. Therefore, the opening peripheral edge portion 14a of the rear bracket 14 is formed thin. In the first embodiment, the rear bracket 14 is formed in a small size. Specifically, the outer diameter of the rear bracket 14 is set within a range of 60 mm to 68 mm.

  The rear bracket 14 includes a power feeding unit E that is electrically connected to the rotor 30 and a brush device 40. The power feeding unit E has a terminal bolt 100 fixed to the rear bracket 14, and the terminal bolt 100 is connected to an external power source (not shown). The brush device 40 includes a brush holder 42 and a plurality of brush accommodating portions 48 formed on the brush holder 42, and the plurality of brush members 50 accommodated in the brush accommodating portion 48 are included in the disk commutator 32. It is in sliding contact with the conductive portion 36.

  The power feeding unit E has a terminal bolt 100. The terminal bolt 100 is inserted into the through hole 106 formed in the rear bracket 14 through the brush device 40 from the inside of the rear bracket 14. A nut 108 is screwed into the terminal bolt 100 inserted into the through hole 106 from the outside of the rear bracket 14. Accordingly, the terminal bolt 100 is fixed to the rear bracket 14 by the nut 108.

  At the center of the rear bracket 14, a cylindrical boss portion 14b is formed to protrude, and an oilless metal 22 is press-fitted into the boss portion 14b. One end portion 24a of the shaft 24 of the rotor 30 is inserted into the oilless metal 22 press-fitted into the boss portion 14b. That is, the rotor 30 is rotatably supported by the rear bracket 14.

  The brush holder 42 is insert-molded including both the positive terminal plate 70 and the negative terminal plate (not shown). In the embodiment, the positive terminal plate 70 and the negative terminal plate are metal plates formed by pressing. Further, the brush holder 42 includes a cylindrical portion 44 that externally fits the boss portion 14 b formed on the rear bracket 14, and a flange portion 46 that is formed at one end of the cylindrical portion 44 and contacts the bottom surface of the rear bracket 14. And a plurality of brush accommodating portions 48 formed on the flange portion 46 so as to surround the cylindrical portion 44. In the brush accommodating portion 48, positive brush members 50 and negative brush members (not shown) are alternately accommodated, and the positive brush members 50 and the negative brush members are respectively formed in the same shape by a carbon material or the like. ing. The positive brush member 50 and the negative brush member are urged by a compression coil spring 62 (see FIG. 3) accommodated in the brush accommodating portion 48 and are in sliding contact with the conductive portion 36 of the disk commutator 32. A pigtail of the positive brush member 50 is connected to the head 102 of the terminal bolt 100.

  As shown in FIG. 2, the conductive portion 36 is formed in a fan shape that is narrow on the center side (axial center of the rotor shaft 24) side of the disk commutator 32 and wide on the outside in the radial direction. A plurality of conductive portions 36 are arranged on the end face in the axial direction of the disk commutator 32 in a radial manner and at equal angular intervals in the circumferential direction.

  The brush member 50 is formed in a rectangular parallelepiped as a whole. In FIG. 2, the slidable contact surface 50a of the brush member 50 is the back surface side in the figure, but the outer shape that is the shape of the slidable contact surface 50a is as illustrated. , Is rectangular as shown in the figure. The brush member 50 is disposed so that both long sides of the rectangle are parallel to the diameter of the disk commutator 32. Thus, for example, when the disk commutator 32 rotates as indicated by the arrow N in the figure, it corresponds to one long side that becomes the front side of the sliding contact surface 50a when the conductive portion 36 is moved and switched to each conductive portion 36. The edge 50b and the edge 50c corresponding to the other long side on the rear side are a plan view as viewed from the axial direction of the disk commutator 32 with respect to a boundary (gap) 36a dividing each conductive portion 36 (state in FIG. 2) ) In the state where the conductive portion 36 is switched.

  Therefore, when the front edge 50 b starts to move to the next of the conductive portions 36, it starts to move from the radially inner side of the disk commutator 32. Further, when the rear edge 50c finishes moving to the next one of the conductive portions 36, the rear edge 50c finishes moving from the outside in the radial direction of the disk commutator 32. In this way, the switching of the brush member 50 to the next conductive portion 36 is performed gradually, and the two conductive portions 36 adjacent to each other as shown by the arrow A in FIG. This is repeated as the disk commutator 32 rotates.

  FIG. 3A shows a change in the contact area to the conductive portion 36 with respect to the relative movement amount (rotation angle of the disk commutator 32) with the conductive portion 36 in the brush member 50 in this case, and similarly, the brush member with respect to the relative movement amount. FIG. 3B shows a change in the contact resistance between 50 and the conductive portion 36. In both figures, the change with respect to the conductive portion 36 where the brush member 50 first comes into contact is indicated by a solid line, and the conductive portion 36 where the brush member 50 starts to come into contact is indicated by a two-dot chain line. As shown in the figure, when the brush member 50 starts to contact the first conductive portion 36, the contact area gradually increases as described above, and the contact resistance gradually decreases accordingly. Similarly, the gradual change occurs in the first separation from the conductive portion 36. The same applies to the second conductive portion 36.

  As the change in the contact area and the contact resistance becomes gentle in this way, as shown in the solid line of FIG. 4, for example, an inclined portion that shifts from a state in which a positive current flows to a state in which a negative current flows is obtained. Almost straight. The closer the slope of the positive / negative transition slope is, the better the rectification is, and since the slope is almost constant, there is no part that changes greatly, and it is possible to prevent the occurrence of sparks.

  On the other hand, the case of a conventional trapezoidal brush will be described with reference to FIG. 5A corresponding to FIG. 3A and FIG. 5B corresponding to FIG. In addition, the change with respect to the electroconductive part 36 which the brush member 50 begins to contact first similarly to the above is shown as the continuous line, and the electroconductive part 36 which begins to contact next is shown with the dashed-two dotted line.

  As shown in FIG. 5, the change is abrupt when the contact starts or leaves. This is because it is trapezoidal as described above, so that the edge of the brush is aligned with the boundary 36a of the conductive portion 36 and is switched at once. The rectification curve in the case of this conventional trapezoidal brush is an inclined curve that undulates as shown by a two-dot chain line in FIG. In that case, when the positive current starts to move from the constant state to the negative side, and vice versa, the slope becomes steep, and as a result, the spark is likely to be generated due to a large change.

  In the present invention, since the rectification curve is almost a straight line as described above, it changes with a constant slope, no sparks are generated, and wear due to the occurrence of sparks is prevented, so that a good rectification characteristic is stable over a long period of time.

  In addition, as shown in FIGS. 1 and 6, the sliding contact surface 50a of the brush member 50 has a groove 50d parallel to both long sides in the illustrated example as a recess in the sliding contact surface 50a. It is formed at a center position with respect to the sliding contact direction. As a result, a pressure higher than the contact pressure of the normal-shaped brush can be applied to both end portions (front and rear end portions in the sliding contact direction) of the brush member 50 in a balanced manner. Therefore, a high contact pressure is applied to both end portions of the brush member 50. Since both ends of the brush member 50 are in sliding contact with the disk commutator 32 with certainty, the characteristics of the motor are stabilized even in the initial stage of use of the motor. The concave portion is not limited to the groove 50d, and the extending direction in the case of the groove 50d is not limited to the illustrated example.

  By providing the groove 50d in the sliding contact surface 50a in this manner, the contact area of the sliding contact surface 50a with the disk commutator 32 is reduced, so that when the spring 51 having the same urging force (same spring constant etc.) is used. The load per unit area on the conductive portion 36 of the brush member 50 can be increased. Furthermore, by increasing the contact pressure, the initial familiarity between the disk commutator 32 and the brush member 50 can be shortened, and the initial characteristics of the motor can be stabilized at an early stage.

  Further, the shape of the brush member 50 (sliding contact surface 50a) in a plan view as viewed from the axial direction of the disk commutator 32 is not limited to the rectangle in FIG. 1, and some other examples are shown in FIG. . In FIG. 7A, the front edge 50b, which is a forward direction relative to the conductive portion 36 of the brush member 50, is the same as that in the illustrated example, but the rear edge 50c, which is the opposite side, is the brush member 50. Is formed so as to have a hypotenuse coincident with the boundary 36a in a state where it is aligned with two adjacent conductive portions 36. Further, in FIG. 7B, the rear edge 50c is formed to be a hypotenuse that coincides with the boundary 36a, contrary to FIG. 7A. Also in these cases, since the sliding contact surface 50a is gradually shifted when the next conductive portion 36 is switched, the above-described operation and effect can be obtained.

32 Disc commutator 36 Conductive portion 40 Brush device 42 Brush holder 48 Brush holding portion 50 Brush 50a Sliding contact surface 50b / 50c Edge 50d Groove

Claims (5)

A brush device of a rotating electrical machine having a brush that is in sliding contact with a plurality of segments of a disk commutator in which segments made of a fan-shaped conductor are arranged radially on a plane,
At least one edge of the front side and the rear side in the sliding contact direction on the sliding contact surface of the brush,
A brush device for a rotating electrical machine formed so as to be skewed with respect to the boundary line on a boundary line dividing the plurality of segments.   The brush device for a rotating electrical machine according to claim 1, wherein a concave portion is provided on the sliding surface.   The brush device for a rotating electrical machine according to claim 2, wherein the concave portion is provided in the center with respect to the sliding contact direction on the sliding contact surface.   The brush device for a rotating electrical machine according to any one of claims 1 to 3, wherein the sliding surface is formed in a rectangular shape.   5. A rotating electrical machine comprising: the brush device of the rotating electrical machine according to claim 1; a housing to which the brush device is fixed; and a rotor that is rotatably supported by the housing.

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