Commutator and direct current motor

Abstract

The invention provides a commutator and a DC motor, the commutator comprises a cylindrical main body (13) and a plurality of commutator segments (11) surrounding the periphery of the main body (13), grooves (12) are formed between adjacent commutator segments (11) in the circumferential direction (C) of the main body (13), and the direction of the grooves (12) is not completely flush with the axial direction (A) of the main body (13). According to the commutator, the radial runout of the electric brush can be reduced, and the NVH problem of the motor is reduced; and the current cannot be suddenly interrupted, so that electric sparks are avoided or reduced. According to the direct current motor, the NVH problem is small, the current cannot be suddenly interrupted, and electric sparks cannot be generated easily.

Description

Technical Field

[0001] The present invention relates to the field of motors, and more particularly to a commutator and a DC motor. Background Art

[0002] Figure 1 Taking the partial structure of the coreless motor as an example, a commutator 10 connected to the rotor R is shown. When direct current passes through the coil in the motor, a magnetic field is generated, causing the rotor R in the motor to rotate. However, since the direction of the direct current is constant, the rotor R can only rotate halfway and then stop. In order to make the rotor R continue to rotate, the current direction of the power supply needs to be changed with the help of the commutator 10 and the brush 20.

[0003] The commutator 10 is electrically connected to the rotor. The commutator 10 includes a plurality of commutator segments 11 spaced apart in the circumferential direction, and slots 12 are formed between adjacent commutator segments 11. The slots 12 are parallel to the axial direction of the commutator 10. Two brushes 20 are respectively connected to the positive and negative poles of the power supply, and the two brushes 20 abut against two different commutator segments 11 of the commutator 10. In the process of the commutator 10 rotating with the rotor R, the brushes 20 guide the periodically changing current direction to the commutator 10.

[0004] However, the applicant found that this commutator has the following shortcomings: First, during the commutation process, that is, when the brush 20 passes through the slot 12, the brush 20 will partially not be supported in the radial direction, so that the brush 20 will move radially inward; when the brush 20 is at a position facing the outer periphery of the commutator segment 11 again, the brush 20 will move radially outward again. When the rotor speed is high, the brush 20 will have a non-negligible radial runout, causing NVH problems and brush 20 wear problems.

[0005] Second, during the rotation of the commutator 10, the brush 20 switches between the outer sides of the slot 12 and the outer sides of the commutator segment 11 in a continuous and sudden manner, and the current is suddenly interrupted, thereby generating commutation sparks, which not only endangers safety but may also interfere with surrounding electronic equipment and communication systems. Summary of the invention

[0006] The purpose of the present invention is to overcome or at least alleviate the deficiencies of the above-mentioned prior art and to provide a commutator and a DC motor.

[0007] According to a first aspect of the present invention, there is provided a commutator, comprising a cylindrical body and a plurality of commutator segments surrounding the outer circumference of the body, wherein grooves are formed between adjacent commutator segments in the circumferential direction of the body. The groove is not completely flush with the axial direction of the main body.

[0008] In at least one embodiment, any auxiliary line parallel to the axial direction is made in the slot, and the auxiliary line passes through at least one of the commutator segments.

[0009] In at least one embodiment, when the auxiliary line translates in the slot along the circumferential direction, there is a position where the auxiliary line passes through two commutator segments at the same time.

[0010] In at least one embodiment, each of the commutator segments is formed with a plurality of protrusions and a plurality of recesses facing another circumferentially adjacent commutator segment, and the protrusions of one of the two circumferentially adjacent commutator segments and the recesses of the other are aligned in the axial direction.

[0011] In at least one embodiment, the number of protrusions on each commutator segment is equal.

[0012] In at least one embodiment, the protrusions on each of the commutator segments have the same shape.

[0013] In at least one embodiment, at different positions in the circumferential direction, the width of the protrusion in the axial direction varies. The width of the protrusion gradually decreases along the direction in which the brush moves away from the commutator segment.

[0014] In at least one embodiment, each of the grooves has a centrally symmetrical shape.

[0015] According to the second aspect of the present application, a DC motor is provided, comprising a stator, a rotor, a commutator and a brush, wherein the commutator is electrically connected to the rotor, the brush is abutted against the outer peripheral wall of the commutator and can rotate relative to the commutator, and is characterized in that the commutator is the commutator provided according to the first aspect of the present application.

[0016] In at least one embodiment, the rotor is a coreless rotor including windings but not an iron core.

[0017] The commutator according to the present invention can reduce the radial runout of the brush and reduce the NVH problem of the motor; and prevent the current from being suddenly interrupted, thereby avoiding or reducing electric sparks. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of a partial structure of a coreless cup motor including a commutator in the prior art.

[0019] Figure 2 is a schematic diagram of a commutator according to one embodiment of the present application.

[0020] Figure 3 It is a schematic diagram of adjacent commutator segments of a commutator according to one embodiment of the present application unfolded along the circumferential direction.

[0021] Figures 4 to 6 A schematic diagram showing the position of the brush as it slides between two adjacent commutator segments.

[0022] Figures 7 to 9 It is a schematic diagram of three variant commutator segment structures of the commutator according to the present application unfolded along the circumferential direction.

[0023] Description of reference numerals: R rotor; 10 commutator; 11 commutator segment; 111 convex portion; 112 concave portion; 12 slot; 13 body; 20 brush; C circumferential direction; A axial direction; L1 first auxiliary line; L2 second auxiliary line; L3 third auxiliary line. DETAILED DESCRIPTION

[0024] The exemplary embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood that these specific descriptions are only used to teach those skilled in the art how to implement the present invention, and are not intended to exhaust all possible modes of the present invention, nor to limit the scope of the present invention.

[0025] Reference Figures 2 to 6 , introduces a commutator according to an embodiment of the present application. Unless otherwise specified, refer to Figure 2 and Figure 3 , A represents the axial direction of the commutator, and C represents the circumferential direction of the commutator.

[0026] Reference Figure 2 The commutator 10 of this embodiment includes a cylindrical body 13 and a plurality of commutator segments 11 surrounding the outer circumference of the body 13. There is a gap between adjacent commutator segments 11 in the circumferential direction C to form a slot 12. The biggest difference between this embodiment and the prior art is that the extension direction of the slot 12 is not completely flush with the axial direction A, but extends in a zigzag manner relative to the axial direction.

[0027] Figure 3 The schematic diagram of two commutator segments 11 adjacent to each other in the circumferential direction is shown in a simplified manner. The figure is used to specifically show the structure of the edges of the two commutator segments 11 adjacent to each other, while ignoring the specific structure of the edges of the two commutator segments 11 that are separated from each other in the circumferential direction (the edges are simplified and replaced by a form parallel to the axial direction). The number of convex parts 111 and concave parts 112 in the figure does not represent the number of convex parts and concave parts on each commutator segment in reality, and the proportional relationship of each structure in the figure is not used to represent the proportional relationship of specific parts of the actual commutator segment.

[0028] The meandering structure of the groove 12 is because the circumferential edge of each commutator segment 11 is formed with a convex portion 111 and a concave portion 112 facing the adjacent commutator segment 11 , and the convex portion 111 of one of the adjacent commutator segments 11 in the circumferential direction C is aligned with the concave portion 112 of the other in the axial direction A.

[0029] In this embodiment, an auxiliary line is drawn parallel to the axial direction A and passes through the slot 12. It should be understood that there are countless parallel lines, and any one of these auxiliary lines satisfies the requirement that no matter where the auxiliary line is located on the circumferential direction C in the slot 12, the auxiliary line will pass through at least one commutator segment 11. The "passing" mentioned here includes the situation of contacting the inside of the commutator segment 11, and also includes the situation of contacting the edge of the commutator segment 11. For example Figure 3 The figure shows the first auxiliary line L1, the second auxiliary line L2 and the third auxiliary line L3 located at three different circumferential positions in the slot 12, wherein the first auxiliary line L1 passes through an upper commutator segment 11, the second auxiliary line L2 passes through the edges of two commutator segments 11 at the same time, and the third auxiliary line L3 passes through a lower commutator segment 11.

[0030] Reference Figures 4 to 6 , the advantages of the above-mentioned structure of the commutator segment 11 and the slot 12 are introduced. Figures 4 to 6 The process of the brush 20 sliding from one commutator segment 11 to another commutator segment 11 in the circumferential direction is simulated, and the hollow arrow in the figure shows the sliding direction of the brush 20 relative to the commutator segment 11.

[0031] Figure 4 The state in which the brush 20 is about to leave the upper commutator segment 11 is shown. Although the brush 20 has partially entered the slot 12 and partially lost radial support, the convex portion 111 still has a partial supporting effect on the brush 20.

[0032] Figure 5 The state where the brush 20 is further away from the upper commutator segment 11 and partially connected to the lower commutator segment 11 is shown. In this process, the convex portion of the upper commutator segment 11 continues to support the brush 20, and the area of ​​the convex portion of the lower commutator segment 11 supporting the brush 20 is further increased.

[0033] Figure 6 The state in which the brush 20 is separated from the upper commutator segment 11 and the area supported by the lower commutator segment 11 is gradually increased is shown.

[0034] It can be seen from the above process that according to the commutator of this embodiment, during the entire process of the brush 20 sliding from one commutator segment 11 to another adjacent commutator segment 11, the brush 20 can still be continuously, dynamically, and partially supported near the slot 12, and the radial support effect of the commutator segment 11 on the brush 20 is much greater than the prior art described above. Therefore, the radial runout of the brush 20 is reduced, the NVH problem of the motor is reduced, and the wear of the brush 20 is slowed down.

[0035] In addition, when the brush 20 passes through the slot 12, the presence of the recess 112 and the protrusion 111 will make the reduction and increase of the contact area between the brush 20 and the commutator segment 11 smaller than that in the prior art, and in this process, the current will not be suddenly interrupted, thereby reducing electric sparks.

[0036] Preferably, the number of protrusions 111 of two adjacent commutator segments 11 is equal; more preferably, the number and shape of the protrusions 111 of each commutator segment 11 in the commutator 10 are the same, so that when the brush 20 slides between adjacent commutator segments 11, the contact area between the brush 20 and the commutator segment 11 changes periodically and evenly.

[0037] Preferably, the profile of each slot 12 forms a centrally symmetrical figure, which means that the convex portions 111 on both sides of the slot 12 are evenly and staggeredly distributed in the axial direction, so that when the brush 20 passes through the slot 12, the supporting force received at various locations in the axial direction is more uniform.

[0038] Figure 7 A variation of this embodiment is shown. In this variation, along the direction in which the brush (not shown in the figure) leaves the commutator segment 11 in the circumferential direction C, that is, the direction indicated by the hollow arrow in the figure for the commutator segment 11 located above, the size of the protrusion 111 in the axial direction A is gradually reduced; or, along the direction in which the brush enters the commutator segment 11 in the circumferential direction, that is, the direction indicated by the hollow arrow in the figure for the commutator segment 11 located below, the size of the protrusion 111 in the axial direction A is gradually increased. This structure allows the amount of reduction and increase in the contact area between the brush and the commutator segment 11 to change evenly during the process of the brush passing through the slot 12, thereby better reducing the radial runout of the brush 20, making the current change more stable, and thus reducing sparks.

[0039] Figure 8 Another variation of this embodiment is shown. In this variation, the width of the slot 12 in the circumferential direction C is further reduced, and adjacent convex portions 111 have overlapping areas G in the circumferential direction C. This makes it possible for the brush to be supported by the convex portion 111 with a longer probability or time when the brush passes through the slot 12, thereby better reducing the radial runout of the brush 20, making the current change more stable, and further reducing sparks.

[0040] Fig. 9 Another variation of this embodiment is shown. In this variation, the edge of the groove 12 is curved. This embodiment is for illustration only, and the present application does not limit the specific shapes of the convex portion 111 and the concave portion 112.

[0041] It should be understood that the above-mentioned embodiments and some aspects or features thereof may be appropriately combined.

[0042] The present application also provides a DC motor including the aforementioned commutator, wherein the rotor of the DC motor may be a hollow cup rotor having a winding but not an iron core.

[0043] Of course, the present invention is not limited to the above-mentioned embodiments, and those skilled in the art may make various modifications to the above-mentioned embodiments of the present invention under the guidance of the present invention without departing from the scope of the present invention.

Claims

1. A commutator, comprising a cylindrical body (13) and a plurality of commutator segments (11) surrounding the outer periphery of the body (13), wherein grooves (12) are formed between adjacent commutator segments (11) in a circumferential direction (C) of the body (13), characterized in that: The direction of the groove (12) is not completely flush with the axial direction (A) of the main body (13).

2. The commutator according to claim 1, characterized in that: Any auxiliary line parallel to the axial direction (A) is made in the slot (12), and the auxiliary line passes through at least one of the commutator segments (11).

3. The commutator according to claim 2, characterized in that: During the process of translation of the auxiliary line in the slot (12) along the circumferential direction (C), there is a position where the auxiliary line passes through two commutator segments (11) at the same time.

4. The commutator according to claim 2, characterized in that: Each of the commutator segments (11) is formed with a plurality of convex portions (111) and a plurality of concave portions (112) facing another commutator segment (11) adjacent in the circumferential direction, and the convex portion (111) of one of the two commutator segments (11) adjacent in the circumferential direction and the concave portion (112) of the other are aligned in the axial direction.

5. The commutator according to claim 4, characterized in that: The number of protrusions (111) on each commutator segment (11) is equal.

6. The commutator according to claim 4, characterized in that: The convex portion (111) on each commutator segment (11) has the same shape.

7. The commutator according to claim 4, characterized in that: At different positions in the circumferential direction (C), the width of the protrusion (111) in the axial direction (A) varies. Along the direction in which the brush (20) leaves the commutator segment (11), the width of the protrusion (111) gradually decreases.

8. The commutator according to claim 2, characterized in that: Each of the grooves (12) has a centrally symmetrical shape.

9. A direct current motor, comprising a stator, a rotor, a commutator (10) and a brush (20), wherein the commutator (10) is electrically connected to the rotor, and the brush (20) is in contact with the outer peripheral wall of the commutator (10) and can rotate relative to the commutator (10), characterized in that: The commutator (10) is a commutator according to any one of claims 1 to 8.

10. The DC motor according to claim 9, characterized in that: The rotor is a hollow cup rotor (R) including windings but not including an iron core.

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