motor

Abstract

The present invention provides a small motor with a long service life. The motor (1) comprises: a frame (10) having a width of less than 10 mm; an annular magnet (50) mounted on the inner surface of the frame (10); a bracket (30) disposed on the frame (10); a columnar brush (25) formed of carbon; a commutator (6) in contact with the outer peripheral surface of the brush (25); and a support portion (21) supporting the brush (25) on the bracket (30), the support portion (21) being located inside the brush (25).

Description

Technical Field

[0001] The present invention relates to motors, and more particularly to motors with brushes. Background Art

[0002] Conventionally, various structures have been proposed for motors having brushes.

[0003] Patent Document 1 below describes a motor structure in which spaces for dispersing brush wear powder generated by sliding between the brush and the commutator are provided between adjacent brush holders and between the brush holder and the housing, thereby preventing brush wear from concentrating between the commutators and causing leakage.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2001-231222

[0005] However, in recent years, in applications requiring high torque, there is a demand for miniaturization of motors. In a small motor, in order to output a high-torque driving force, a large current needs to flow through the motor. On the other hand, in a smaller motor, the intervals between adjacent commutators are relatively narrow, so there is a problem that short circuits are easily caused by the concentration of brush wear powder between adjacent commutators. In addition, for a small motor with a frame width of less than 10 mm, it is difficult to use a structure that utilizes a relatively large brush size as described in the above-mentioned Patent Document 1. Summary of the invention

[0006] The present invention takes the above-mentioned problem as an example, and an object of the present invention is to provide a motor which is small in size and has a long life.

[0007] In order to achieve the above-mentioned object, according to one aspect of the present invention, a motor comprises: a frame having a width of less than 10 mm; an annular magnet mounted on the inner surface of the frame; a bracket arranged on the frame; a columnar brush formed of carbon; a commutator in contact with the outer peripheral surface of the brush; and an elastic component which supports the brush on the bracket and is located inside the brush.

[0008] Preferably, the commutator includes a plurality of commutator segments arranged in a circumferential direction, and the width of the outer peripheral surface of the brush in the circumferential direction is the same as or smaller than the width of the commutator segments.

[0009] Preferably, the bracket has an opening facing the brush in the rotation axis direction.

[0010] Preferably, a commutator is disposed inside the opening, and a portion of the opening facing the brush, the commutator, and another portion of the opening are arranged in a radial direction.

[0011] Preferably, the planar shape of the opening has a long-side direction and a short-side direction.

[0012] Preferably, a rib is provided on the outer peripheral surface of the bracket, and the rib is in contact with the inner surface of the frame.

[0013] Preferably, a plurality of brushes including a brush and a plurality of elastic members including an elastic member are provided, and one of the plurality of brushes is located at a higher position than the other brushes in the rotation axis direction.

[0014] Preferably, one brush can come into contact with the other brushes, and an elastic member supporting one brush among the plurality of elastic members can intersect with an elastic member supporting the other brushes.

[0015] According to another aspect of the present invention, a motor comprises: a frame, a plurality of magnets mounted on the inner surface of the frame, a bracket arranged on the frame, a columnar brush formed of carbon, a commutator in contact with the outer peripheral surface of the brush, and an elastic component supporting the brush on the bracket, wherein the plurality of magnets are arranged in a circumferential direction and the elastic component is located inside the brush.

[0016] According to yet another aspect of the present invention, a motor comprises: a frame, a magnet mounted on the inner surface of the frame, a bracket arranged on the frame, a plurality of columnar brushes formed of carbon, a commutator in contact with the outer peripheral surface of the brush, and an elastic component supporting the brush on the bracket, wherein the elastic component is located inside the brush, and in the direction of the rotating axis, one of the plurality of brushes is located at a higher position than the other brushes.

[0017] According to the above invention, a motor which is compact and has a long life can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a cross-sectional view showing a motor according to an embodiment of the present invention.

[0019] Figure 2 It is schematically indicated Figure 1 A cross-section diagram of the AA line.

[0020] Figure 3 It is the front view of the brush unit.

[0021] Figure 4 is a side view of the brush unit.

[0022] Figure 5 This is the rear view of the motor.

[0023] Figure 6 It is a front view showing the bracket to which the brush unit is mounted.

[0024] Figure 7 is a side view of the bracket.

[0025] Figure 8 This is a diagram showing a first state of the bracket to which the brush unit is attached.

[0026] Fig. 9 yes Figure 8 Side sectional view of .

[0027] Fig.10 This is a diagram showing a second state of the bracket to which the brush unit is attached.

[0028] Fig.11 yes Fig.10 Side sectional view of .

[0029] Fig.12 This is a diagram for explaining the positional relationship between two brushes and a commutator in the front-rear direction.

[0030] Description of Reference Numerals

[0031] 1...motor; 1a...frame assembly; 1b...armature assembly; 2...rotating shaft; 6...commutator; 7...commutator segment; 10...frame; 20b, 20c...brush unit; 21...support portion (an example of an elastic member); 25...brush; 30...bracket; 36...opening portion; 39...rib; 40...cover plate; 50...magnet. DETAILED DESCRIPTION

[0032] Hereinafter, a motor according to an embodiment of the present invention will be described.

[0033] In the following description, the direction parallel to the rotation axis of the motor is sometimes referred to as the rotation axis direction. In addition, the rotation axis direction is sometimes referred to as the front-to-back direction (the direction in which the bracket is provided is the rear direction when viewed from the frame of the motor). In addition, a specific direction (to be described later) in the direction perpendicular to the rotation axis of the motor (radial direction) is sometimes referred to as the up-down direction, and the direction perpendicular to the front-to-back direction and the up-down direction is referred to as the left-right direction. The terms "front-to-back", "up-down", "left-to-right", etc. mentioned here are expressions adopted for convenience when focusing only on the motor, and do not impose any limitation on the direction of the device equipped with the motor or the posture of using the motor.

[0034] [Implementation Method]

[0035] Figure 1 It is a cross-sectional view showing a motor according to an embodiment of the present invention. Figure 2 It is schematically indicated Figure 1 A cross-section diagram of the AA line.

[0036] Figure 1 The cross section shown is Figure 2 In addition, some structural components are schematically shown (for example, the brush unit 20c described later is represented by a double-dashed line.) In the following figures, arrow A1 indicates the direction of the rotation axis, that is, the front-to-back direction. Arrow A2 indicates the left-right direction ( Figure 2The middle left is the left direction). Arrow A3 indicates the up and down direction ( Figure 2 Middle and upper is above).

[0037] The motor 1 includes a frame assembly 1a and an armature assembly 1b that can rotate relative to the frame assembly 1a. The motor 1 is a small motor with a width of 10 mm or less. Here, the width of the motor 1 may be, for example, the distance between a pair of planar portions 11 that are opposed to each other across the rotating shaft 2, the size of the motor 1 in the vertical direction or the size in the horizontal direction, or the maximum outer diameter of the motor 1.

[0038] The armature assembly 1b includes: a rotating shaft (shaft body) 2, an armature 4 mounted on the rotating shaft 2, and a commutator 6 mounted on the rotating shaft 2. The armature 4 is mounted on the rotating shaft 2. The armature 4 includes: an armature core 5 having a plurality of radially protruding salient poles, and a winding (not shown) wound around each salient pole. The commutator 6 is disposed near one end of the rotating shaft 2. The commutator 6 includes a plurality of commutator segments 7 arranged in the circumferential direction. The plurality of commutator segments 7 are electrically connected to the windings, respectively.

[0039] The frame assembly 1 a is composed of a frame (motor housing) 10 , a bracket 30 , a cover plate 40 , a magnet 50 , and the like.

[0040] The frame 10 has a front end, a rear end, a surface (cap) that closes the front end, and a cylinder. That is, the frame 10 has a cup shape with the rear end being an opening. Figure 1 The opening of the frame 10 (the right end in the middle) is blocked by a cover plate 40. The armature 4, the commutator 6 and the like of the armature assembly 1b are housed in a housing composed of the frame 10 and the cover plate 40.

[0041] The frame 10 is formed using a magnetic material. Figure 2 As shown, the frame 10 has: a plurality of corners 12, and a plane portion 11 between two adjacent corners 12. Specifically, the frame 10 has an outer shape having four plane portions 11 and four corner portions 12, respectively. Two plane portions 11 adjacent to each other in the circumferential direction are connected to each other via a corner portion 12. One of the two plane portions 11 adjacent to each other in the circumferential direction is approximately perpendicular to the other. The corner portion 12 has a rounded shape (R shape). The frame 10 is approximately square in a cross section perpendicular to the rotating shaft 2. The frame 10 is formed in a square shape as a whole. That is, the motor 1 is a small square motor. In addition, in the following description, the up-down direction is a direction perpendicular to a pair of plane portions 11 that exist in a manner of clamping the rotating shaft 2, and the left-right direction is a direction perpendicular to another pair of plane portions 11 that exist in a manner of clamping the rotating shaft 2.

[0042] return Figure 1, a bracket 30 is arranged on the inner side of the cover plate 40. The bracket 30 is set on the frame 10. The bracket 30 has two brush units 20b and 20c (hereinafter, sometimes the two brush units 20b and 20c are not distinguished and are referred to as brush units 20). Each brush unit 20 has: a brush 25, which is in contact with the commutator 6; a terminal portion 28, which is supplied with current from the outside; and a metal support portion (an example of an elastic member) 21, which electrically connects the brush 25 and the terminal portion 28. The terminal portion 28 is mounted on the bracket 30. That is, the support portion 21 supports the brush 25 on the bracket 30. The support portion 21 is formed of an elastic member having elasticity, and holds the brush 25 on the bracket in a state where the commutator 6 is in contact with the outer surface of the brush 25.

[0043] The rotating shaft 2 penetrates the front surface of the frame 10. That is, the front end of the rotating shaft 2 protrudes from the frame 10 to the outside of the frame 10, and the other part of the rotating shaft 2 is accommodated inside the frame 10. A bearing holding portion 10g is provided at the central portion of the front surface of the frame 10, and a bearing 18 is held in the bearing holding portion 10g. In addition, a bearing 19 is held at the central portion of the cover plate 40. A thrust washer 19b is arranged behind the bearing 19. The rotating shaft 2 is supported by the bearings 18 and 19 at two positions and the thrust washer 19b so as to be rotatable relative to the frame 10.

[0044] like Figure 2 As shown in the figure, in the present embodiment, a ring-shaped magnet 50 is provided. In other words, the magnet 50 is formed in a cylindrical shape. The magnet 50 is arranged on the inner side of the frame 10. The frame assembly 1a has a cross-sectional structure formed by the outer peripheral surface 50a of the magnet 50 surrounded by the frame 10. The outer peripheral surface of the frame 10 becomes the outer peripheral surface of the motor 1. In addition, a plurality of magnets each having a magnetic pole element may be used.

[0045] The frame 10 has a substantially uniform thickness. That is, the inner surface 10 b of the frame 10 is formed by connecting a plurality of flat portions based on the plane portion 11 and a plurality of rounded portions based on the corner portion 12 , and is formed in a square shape.

[0046] The magnet 50 is, for example, a bonded magnet formed using a known rare earth material and a known resin material. The magnet 50 is not limited to a bonded magnet, and may be, for example, a sintered magnet.

[0047] The magnet 50 has magnetic pole elements 61 (N pole 61a, S pole 61b, N pole 61c, S pole 61d). That is, the magnet 50 has the same number of magnetic pole elements 61 as the number of corners 12 of the motor 1. The magnetic pole elements 61 are arranged so that the polarities are different from each other along the circumferential direction. The four magnetic pole elements 61 are arranged so that the magnetic pole elements 61 face each other at the four corners 12 of the frame 10.

[0048] The magnet 50 has a rounded outer peripheral surface 50a along the inner surface 10b of the frame 10 at the corner 12. The magnet 50 also has a cylindrical inner peripheral surface 50b. A slight air gap is provided between the inner peripheral surface 50b of the magnet 50 and the armature core 5.

[0049] In the present embodiment, the magnet 50 is fixed to the frame 10 using an adhesive 59. That is, the adhesive 59 is present between the rear end of the magnet 50 and the inner surface 10b of the frame 10. In the assembly process of the motor 1, the magnet 50 is inserted into the inner side of the frame 10 from the opening on the rear side of the frame 10. Moreover, the adhesive 59 is disposed between the rear end of the magnet 50 and the inner surface 10b of the frame 10, and the magnet 50 is fixed to the frame 10. Thereafter, the armature assembly 1b is mounted on the frame 10, and the bracket 30 and the cover plate 40 are mounted on the frame 10 to assemble the motor 1.

[0050] Figure 3 It is a front view of the brush unit 20b. Figure 4 2 is a side view of the brush unit 20b.

[0051] Figure 3 , a view showing the brush unit 20b as viewed from the front is shown. Figure 4 2 shows a view of the brush unit 20b from the right. The brush unit 20b is the motor disposed on the left side of the motor 1 among the two brush units 20b and 20c, and the brush unit 20c is the motor disposed on the right side of the motor 1. The left brush unit 20c and the right brush unit 20b are constructed symmetrically.

[0052] like Figure 3 as well as Figure 4 As shown, the brush unit 20 b is configured such that the brush 25 and the terminal portion 28 are connected to the support portion 21 .

[0053] In the present embodiment, the support portion 21 is formed by shaping a metal wire. The support portion 21 has: a first extension portion 22 extending toward the terminal portion 28, a coil portion 23, and a second extension portion 24 extending toward the coil portion 23. The first extension portion 22 is fixed to the terminal portion 28 by, for example, welding or the like. The coil portion 23 is provided between the first extension portion 22 and the second extension portion 24. The coil portion 23 is formed by spirally winding a metal wire. By providing the coil portion 23, the second extension portion 24 can be displaced relative to the first extension portion 22 while the coil portion 23 is twisted around the central axis of the coil portion 23. That is, the support portion 21 is a torsion coil spring that twists the second extension portion 24 relative to the first extension portion 22. The central axis of the coil portion 23 is at Figure 3 The first extension portion 22 and the second extension portion 24 extend in a direction perpendicular to the central axis of the coil portion 23 , respectively.

[0054] The second extension portion 24 has an intermediate portion 24b on the coil portion 23 side and a mounting portion 24c on the front end side, separated by a bent portion 24d located in the middle portion. The intermediate portion 24b and the mounting portion 24c extend approximately in a straight line. The mounting portion 24c is bent at the bent portion 24d relative to the intermediate portion 24b in such a manner that the front end portion of the mounting portion 24c leaves the first extension portion 22. Since the second extension portion 24 is bent in this way, the length of the arm of the second extension portion 24 can be ensured to be relatively long even in a small motor 1, and the brush 25 can be brought into contact with the commutator 6 at an appropriate angle. In addition, when the brush 25 is in a non-contact state with the commutator 6, the bent portion 24d is located within or on the circumference of a circle where a plurality of commutator segments 7 are formed from the center of the commutator 6.

[0055] The brush 25 is a carbon brush formed of carbon. The brush 25 is formed of carbon and is therefore softer than the member forming the commutator 6. That is, the member forming the commutator 6 is harder than the member forming the brush 25. The brush 25 is columnar. More specifically, the brush 25 is cylindrical and has a cylindrical outer peripheral surface. The brush 25 is mounted on the mounting portion 24c of the second extension portion 24. The mounting portion 24c penetrates the central portion of the brush 25 in the height direction of the columnar brush 25. That is, the support portion 21 is located inside the brush 25 and passes through the inside of the brush 25. In addition, the end of the support portion 21 may be arranged on the outside of the brush 25 instead of passing through the inside of the brush 25, and it may be located inside the brush 25, for example.

[0056] Figure 3 In FIG. 1 , the double-dashed line represents the commutator 6 and the brush unit 20b in a state where the commutator 6 is in contact with the outer peripheral surface of the brush 25. In the present embodiment, the height dimension ( Figure 3 The circumferential dimension of the commutator segment 7 in contact with the brush 25 ( Figure 3 The same as or larger than the circumferential dimension D2 of the commutator segment 7 with which the brush 25 contacts ( Figure 3 That is, in the circumferential direction, the width (dimension D1) of the outer peripheral surface of the brush 25 is smaller than or equal to the width (dimension D2) of the commutator segment 7.

[0057] The terminal portion 28 is formed by using a metal plate, for example. The terminal portion 28 includes a connecting portion 28b connected to the first extension portion 22 of the support portion 21, and a front end portion 28c extending rearward from the connecting portion 28b. The front end portion 28c is provided with an engaging portion such as a claw, a recess, or a protrusion that engages with the bracket 30. The front end portion 28c is a portion that protrudes rearward from the cover plate 40 in the motor 1. By electrically connecting a wire of an external device, a connection terminal of an external device, etc. to the front end portion 28c, power can be supplied to the motor 1.

[0058] The brush unit 20b is mounted on the bracket 30 in a state where the terminal portion 28 is inserted through the mounting hole of the bracket 30. The brush unit 20b is arranged on the bracket 30 in such a manner that the front end portion 28c is inserted into the mounting hole formed in the bracket 30 from the front of the bracket 30. The claw portion, the concave portion, the convex portion, etc. provided at the front end portion 28c is engaged with the engaged portion provided at the bracket 30, so that the terminal portion 28 is fixed to the bracket 30. Thus, the brush 25 is supported by the bracket 30 via the support portion 21.

[0059] When the brush unit 20b is mounted on the bracket 30, the protrusion 34 ( Figure 3 The brush 25 (shown by the dashed line) is inserted into the inner side of the coil portion 23. The coil portion 23 is twisted in a state where the central axis of the coil portion 23 is positioned by the protrusion 34, so that the outer peripheral surface of the brush 25 is in contact with the commutator 6 in a stable manner.

[0060] Figure 5 is a rear view of the motor 1. Figure 6 It is a front view showing the bracket 30 to which the brush unit 20 is mounted.

[0061] Figure 5 For the sake of explanation, the cover plate 40 and the bearing 19 are not shown. Figure 6 , the brush unit 20 is shown with the commutator 6 mounted thereon, and the position of the commutator 6 is indicated by a two-dot chain line.

[0062] like Figure 5 as well as Figure 6 As shown, the bracket 30 is configured to block the opening of the frame 10 of the motor 1. The bracket 30 has an outer peripheral portion 31 embedded inside the frame 10 and a recessed portion 32 that is located inside the outer peripheral portion 31 and recessed toward the rear. The rear side of the bracket 30 is blocked by a plane perpendicular to the rotation axis direction, and an opening 36 for the rotation axis 2 to pass through is formed on the plane.

[0063] The bracket 30 has: four protrusions 33, which are formed on the surface of the rear side; support portions 30c, which are respectively formed on the left and right sides of the rear side and support the terminal portion 28; and protrusions 30b, which are respectively provided at the upper and lower parts of the outer peripheral portion 31 and protrude in the radial direction. Each protrusion 33 is configured to penetrate into the cover plate 40. When the cover plate 40 is mounted on the bracket 30, the end of the protrusion 33 is crushed so that the cover plate 40 and the bracket 30 can be engaged with each other. The front end portion 28c of each left and right brush unit 20 is inserted into the support portion 30c from the front to the rear. The front end portion 28c is in a state of protruding from the support portion 30c to the rear. The protrusion 30b is embedded in the recess formed at the rear end of the frame 10. The position of the bracket 30 in the front-to-back direction relative to the frame 10 is defined by the protrusion 30b and the frame 10.

[0064] In addition, the recess 32 of the bracket 30 is provided with two left and right protrusions 34 and a wall 35 provided inside the terminal portion 28 of each of the left and right brush units 20. The protrusion 34 is, for example, a cylindrical protrusion, and protrudes forward from the bottom of the recess 32 (the surface on the rear side of the bracket 30). Each protrusion 34 is embedded inside the coil portion 23 of the left and right brush units 20 to position the coil portion 23. The wall 35 is a protrusion that protrudes forward from the bottom of the recess 32, and has, for example, a surface that faces the inner peripheral surface of the outer peripheral portion 31 across the terminal portion 28, and a surface that faces the brush 25 of the brush unit 20. The wall 35 is provided between the brush 25 mounted on the second extension portion 24 and the terminal portion 28 mounted on the first extension portion 22, thereby preventing the support portion 21 from being deformed more and causing damage to the support portion 21.

[0065] Figure 7 is a side view of the bracket 30 .

[0066] like Figure 7 As shown in FIG. 1 , ribs 39 are provided on the outer peripheral surface of the outer peripheral portion 31 of the bracket 30. Two ribs 39 are formed on each of the upper surface, the lower surface, the left side surface, and the right side surface of the outer peripheral surface of the outer peripheral portion 31. Each rib 39 protrudes radially from the outer peripheral surface of the outer peripheral portion 31. Each rib 39 is formed so that the front-to-back direction becomes the long side direction. Two ribs 39 are arranged in the circumferential direction on each of the upper surface, the lower surface, the left side surface, and the right side surface of the outer peripheral surface of the outer peripheral portion 31.

[0067] like Figure 5 As shown, each rib 39 contacts the inner surface of the frame 10. Stress is generated in the frame 10 due to the contact of the rib 39. Therefore, the vibration generated by the brush unit 20 is suppressed from propagating to the frame 10 and generating abnormal noise. In addition, the frame 10 is suppressed from vibrating at a relatively low frequency for a relatively long time.

[0068] like Figure 5 As shown in FIG. 1 , in the present embodiment, the shape (planar shape) of the edge of the opening 36 has a shape (elliptical shape (long circular shape)) formed by connecting the ends of two semicircular arcs by two parallel line segments of the same length. In the present embodiment, the dimension of the opening 36 in the vertical direction is longer than the dimension in the horizontal direction. That is, the planar shape of the opening 36 has a long side direction (vertical direction) and a short side direction (horizontal direction).

[0069] In the direction of the rotation axis, the opening 36 faces the brush 25. That is, the brush 25 is exposed at the rear side of the bracket 30 through the opening 36. Figure 1 As shown in FIG. 1 , the commutator 6 is arranged inside the opening 36. Figure 5As shown, a portion of the opening 36 facing the brush 25, the commutator 7, and another portion of the opening 36 are arranged from the lower side of the opening 36 toward the upper side. That is, inside the opening 36, in the radial direction, a portion of the opening 36 facing the brush 25, the commutator 6, and another portion of the opening 36 are arranged.

[0070] The opening 36 has such an elliptical shape, so that when the armature assembly 1b is incorporated into the interior of the frame 10, it can be as follows. That is, first, the armature assembly 1b is inserted into the interior of the frame 10. Then, the bracket 30 on which the brush units 20b and 20c are mounted is mounted to the rear end of the frame 10 from the rear of the armature assembly 1b. At this time, the rotating shaft 2 and the commutator 6 pass through the upper part of the opening 36 that is not opposite to the brush 25. After passing through the opening 36, the position of the frame 10 and the armature assembly 1b relative to the bracket 30 can be adjusted in such a way that the commutator 6 contacts the brush 25. Therefore, the motor 1 can be easily assembled.

[0071] In a state where the commutator 6 and the two brushes 25 are in contact with each other, the two brushes 25 are present at an interval of a predetermined angle G in the circumferential direction of the rotating shaft 2. For example, the angle G is about 90 degrees.

[0072] Figure 8 This is a diagram showing a first state of the bracket 30 to which the brush unit 20 is attached. Fig. 9 yes Figure 8 Side sectional view of . Fig.10 This is a diagram showing a second state of the bracket 30 to which the brush unit 20 is attached.

[0073] Fig.11 yes Fig.10 Side sectional view of .

[0074] exist Fig. 9 as well as Fig.11 In FIG. 1 , a cross section of the bracket 30 is shown, and a view viewed from below is shown instead of a cross section of the brush unit 20 .

[0075] like Figure 8 As shown, in this embodiment, the brush 25 of one of the two brush units 20b and 20c can contact the other brush 25. In addition, the support portion 21 of one of the two brush units 20b and 20c can intersect with the other support portion 21 when viewed from the rotation axis direction.

[0076] When two brush units 20b and 20c are mounted on the bracket 30, first, one brush unit 20b (for example, the left side) is placed on the bracket 30, and then the other brush unit 20c (for example, the right side) is placed on the bracket 30. When the commutator 6 and the like are not in contact with the brush 25, that is, when no force is applied to the support portion 21 in the radial direction of the motor 1, the support portions 21 of the two brush units 20b and 20c intersect with each other when viewed from the front-to-back direction. In this embodiment, as shown in FIG. Figure 8 as well as Fig. 9 As shown in FIG. 1 , the brushes 25 overlap each other in the front-to-back direction. Then, by using a clamp or the like, the two brushes 25 are displaced radially outward from the motor 1 to release the front-to-back overlap of the two brushes 25. Fig.10 as well as Fig.11 As shown in the figure, the mounting portions 24c on the front end side of the brush 25 can be overlapped in the front-rear direction. By making the mounting portions 24c overlapped in the front-rear direction, the process of smoothly deforming the support portions 21 of the two brush units 20b and 20c to bring the commutator 6 into contact with the two brushes 25 can be efficiently performed later.

[0077] In the present embodiment, one of the two brushes 25 is located higher in the rotation axis direction than the other brushes 25. Specifically, the brush 25 of the right brush unit 20c is located forward of the brush 25 of the left brush unit 20b. The two brushes 25 may be located at the same position in the rotation axis direction.

[0078] Fig.12 This is a diagram for explaining the positional relationship between the two brushes 25 and the commutator 6 in the front-rear direction.

[0079] Fig.12 In FIG. 1 , for the purpose of explanation, a portion of the commutator 6 is developed on a plane in the circumferential direction to schematically show the positional relationship between the two brushes 25 and the commutator 6 . An arrow A4 indicates the circumferential direction of the commutator 6 .

[0080] like Fig.12 As shown in FIG. 1 , in this embodiment, the brush 25 of the right brush unit 20c is located slightly forward of the brush 25 of the left brush unit 20b. Therefore, in the front-to-back direction, the area of ​​the commutator 6 that the right brush 25 contacts ( Fig.12 The area indicated by the hatching in the upper left of the middle), and the area of ​​the commutator 6 contacted by the brush 25 on the right side ( Fig.12The area of ​​the two areas that overlap is narrower than when the two brushes 25 are at the same height in the front-to-back direction. Therefore, even if the brush 25 is worn due to the rotation of the motor 1, the wear powder is dispersed in a relatively wide area, and the wear powder is unlikely to stay between adjacent commutator segments 7, and a short circuit or other fault is unlikely to occur.

[0081] As described above, in this embodiment, by using the columnar brush 25, even in the motor 1 in which the width of the frame 10 is 10 mm or less, a structure in which the commutator 6 and the brush 25 are appropriately brought into contact can be realized. The support portion 21 constitutes a torsion spring, and the length of the second extension portion 24 can be relatively long, so that the force for bringing the brush 25 into contact with the commutator 6 can be stably ensured. The amount of change in the force for bringing the brush 25 into contact with the commutator 6 due to the wear of the brush 25 can be reduced.

[0082] The brush 25 is a carbon brush and can be in contact with the commutator 6 without the intermediary of a liquid lubricant, so the motor 1 can be used even in a low-temperature environment.

[0083] The motor 1 uses the annular magnet 50. Therefore, the torque inconsistency can be reduced compared to a motor in which four magnets are arranged at four corners of a frame. In addition, when a large current flows through the commutator 6 via the brush 25, the resonance can be prevented and the generation of abnormal noise can be reduced.

[0084] [other]

[0085] Alternatively, in the above-mentioned embodiment, several feature points may not be provided, or several feature points may be configured in other ways.

[0086] The outer peripheral shape of the motor may not be square as in the above-mentioned embodiment. For example, the brush unit described above may be used in a small motor having a so-called elliptical cross-section (an elliptical shape in which two arcs on the left and right are connected by two straight lines), and may be used in a small motor having a circular cross-section.

[0087] The number of brush units and the number of brushes of the motor are not limited to 2, and may be more than 2. One of the plurality of brushes may be the brush described above, and the other brushes may be brushes of other types.

[0088] It may also be a motor comprising: a frame, a plurality of magnets mounted on the inner surface of the frame, a bracket arranged on the frame, a columnar brush formed of carbon, a commutator in contact with the outer peripheral surface of the brush, and an elastic component supporting the brush on the bracket, wherein the plurality of magnets are arranged in a circumferential direction and the elastic component is located inside the brush. In applications requiring high torque, miniaturization of the motor is required. In a small motor, a larger current can flow through the motor in order to output a high-torque driving force. In addition, the intervals between adjacent commutators are relatively narrow, so that a short circuit caused by the concentration of wear powder of the brush between adjacent commutators can be suppressed.

[0089] The motor may also include a frame, a magnet mounted on the inner surface of the frame, a bracket mounted on the frame, a plurality of columnar brushes formed of carbon, a commutator in contact with the outer peripheral surface of the brush, and an elastic member supporting the brush on the bracket, wherein the elastic member is located inside the brush, and one of the plurality of brushes is located at a higher position than the other brushes in the direction of the rotation axis. Thus, the interval between adjacent commutators is relatively narrow, so that a short circuit caused by the concentration of wear powder of the brush between adjacent commutators can be suppressed.

[0090] When the first extension portion of the support portion is fixed to the terminal portion, welding may be used for fixing if it is difficult to join the member forming the first extension portion and the member forming the terminal portion by welding. Welding may be used for fixing if the motor is a small motor with a width of less than 10 mm and it is difficult to fix by welding.

[0091] In particular, when a high current is applied to the motor to obtain a high torque, the contact resistance value in the joint portion joined by welding sometimes becomes relatively high. Therefore, it is sometimes difficult to obtain a high torque even if a high current is applied. In this case, the desired high torque is sometimes obtained by reducing the contact resistance value in the joint portion by using welding. Therefore, the support portion having the first extension portion and the terminal portion may be fixed by welding, and the brush and the metal wire forming the coil portion may be fixed by welding.

[0092] The number of turns of the metal wire forming the coil portion needs to take into account the contact pressure generated by the contact between the commutator and the brush. In this embodiment, it is 4 turns, but it is not limited to this. The number of turns can also be increased or decreased, and can be appropriately determined considering the contact pressure, the length of the extension portion, and the thickness of the metal wire.

[0093] Alternatively, the coil portion may be positioned in the winding direction of the metal wire by pressing the coil portion into a protrusion provided on the bracket. By positioning the coil portion in the winding direction of the metal wire using the protrusion, the contact pressure between the commutator and the brush can be adjusted. For example, when it is impossible to increase the total height of the motor in the direction of the rotating axis and when it is impossible to ensure space inside the motor, when it is impossible to increase the number of turns of the metal wire, or when it is impossible to increase the thickness of the metal wire, it can be adjusted by positioning the coil portion. In addition, adjustment can be made by increasing or decreasing the angle of the bent portion of the support portion as needed. Furthermore, by making the position of the bent portion of the support portion close to the brush or the coil portion relative to the middle position of the same length from the two ends of the support portion, the spring constant of the support portion is changed, thereby adjusting the contact pressure.

[0094] The motor configured as described above can be used for various purposes, for example, it can be used for electronic equipment or can be mounted on various vehicles.

[0095] The above embodiments should be considered as illustrative in all aspects and have no limiting effect. The scope of the present invention is indicated by the claims rather than the above description, and is intended to include all modifications within the scope and meaning equivalent to the claims.

Claims

1. A motor, wherein: With: framework; an annular magnet mounted on the inner surface of the frame; a bracket disposed on the frame; a columnar brush formed of carbon; a commutator in contact with the outer peripheral surface of the brush; An elastic member supporting the columnar brush on the bracket; as well as Terminal part, The bracket includes an outer peripheral portion, a recessed portion located inside the outer peripheral portion, and a protruding portion and a wall portion provided in the recessed portion. The elastic member includes a first extending portion, a second extending portion, and a coil portion located between the first extending portion and the second extending portion. The first extension portion is fixed to the terminal portion, and the second extension portion is partially located inside the brush. The commutator contacts the columnar brush through the coil portion to generate contact pressure, and the protrusion is located inside the coil portion. The wall portion is disposed between the columnar brush in contact with the commutator and the first extension portion fixed to the terminal portion. The wall portion has a surface facing the columnar brush with a space therebetween around a central axis of the coil portion.

2. The motor according to claim 1, wherein: The commutator has a plurality of commutator segments arranged in a circumferential direction. In the circumferential direction, the width of the outer peripheral surface of the columnar brush is the same as or smaller than the width of the commutator segment.

3. The motor according to claim 1 or 2, wherein: The bracket has an opening facing the columnar brush in the rotation axis direction.

4. The motor according to claim 3, wherein: The commutator is arranged inside the opening. In the radial direction, a portion of the opening portion facing the columnar brush, the commutator, and another portion of the opening portion are arranged.

5. The motor according to claim 3, wherein: The planar shape of the opening has a long side direction and a short side direction.

6. The motor according to claim 1, wherein: A rib is provided on an outer peripheral surface of the bracket, and the rib is in contact with an inner surface of the frame.

7. The motor according to claim 1, wherein: A plurality of columnar brushes including the columnar brush and a plurality of elastic members including the elastic member are provided. In the rotation axis direction, one of the plurality of columnar brushes is located at a higher position than the other columnar brushes.

8. The motor according to claim 7, wherein: The one columnar brush is capable of contacting the other columnar brushes, The elastic member supporting the one columnar brush and the elastic member supporting the other columnar brushes among the plurality of elastic members may intersect with each other.

9. The motor according to claim 1, wherein: The second extension portion includes a bent portion, and the bent portion faces the wall portion around the central axis of the coil portion.

10. The motor according to claim 1, wherein The outer peripheral surface of the columnar brush is cylindrical.

11. The motor according to claim 1, wherein: The second extending portion penetrates the columnar brush in the axial direction of the columnar brush.

12. The motor according to claim 3, wherein: The inner surface of the frame includes two portions facing each other in a direction transverse to the rotation axis, and a distance between the two portions facing each other is 10 mm or less.

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