Commutator and DC motor

Abstract

The present invention provides a commutator and a DC motor. The commutator includes a cylindrical main body (13) and a plurality of commutator segments (11) surrounding the outer periphery of the main body (13). Slots (12) are formed between adjacent commutator segments (11) in the circumferential direction (C) of the main body (13). The direction of the slots (12) is not completely flush with the axial direction (A) of the main body (13). 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. The DC motor according to the present invention has a small NVH problem, does not suffer from sudden current interruptions, and is not prone to generating electric sparks.

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 a partial structure of a coreless motor as an example, a commutator 10 connected to a rotor R is shown. When direct current passes through the motor's coils, it generates a magnetic field, causing the rotor R to rotate. However, because the direction of the direct current is constant, the rotor R can only rotate halfway before stopping. To keep the rotor R rotating, the commutator 10 and brushes 20 are used to redirect the current.

[0003] The commutator 10 is electrically connected to the rotor. It comprises a plurality of circumferentially spaced segments 11, with slots 12 formed between adjacent segments 11. The slots 12 are parallel to the axial direction of the commutator 10. Two brushes 20 are connected to the positive and negative terminals of the power supply, respectively, and abut against two different segments 11 of the commutator 10. As the commutator 10 rotates with the rotor R, the brushes 20 direct the periodically changing direction of the current through the commutator 10.

[0004] However, the applicant found that this commutator has the following deficiencies:

[0005] First, during commutation, when brush 20 passes through slot 12, it is partially unsupported in the radial direction, causing it to move radially inward. When brush 20 again faces the outer periphery of commutator segment 11, it moves radially outward. At high rotor speeds, brush 20 experiences significant radial runout, causing NVH and brush wear.

[0006] 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

[0007] 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.

[0008] 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.

[0009] The groove is not completely flush with the axial direction of the main body.

[0010] In at least one embodiment, any auxiliary line parallel to the axial direction is drawn in the slot, and the auxiliary line passes through at least one of the commutator segments.

[0011] In at least one embodiment, when the auxiliary line translates along the circumferential direction in the slot, there is a position where the auxiliary line passes through two commutator segments at the same time.

[0012] In at least one embodiment, each of the commutator segments is formed with a plurality of protrusions and a plurality of recesses facing the other 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.

[0013] In at least one embodiment, the number of protrusions on each commutator segment is equal.

[0014] In at least one embodiment, the protrusions on each commutator segment have the same shape.

[0015] In at least one embodiment, at different positions in the circumferential direction, the width of the protrusion in the axial direction varies.

[0016] The width of the protrusion gradually decreases as the brush moves away from the commutator segment.

[0017] In at least one embodiment, each of the grooves has a centrally symmetrical shape.

[0018] According to the second aspect of the present application, a DC motor is provided, comprising a stator, a rotor, a commutator and brushes, wherein the commutator is electrically connected to the rotor, the brushes are abutted against the outer peripheral wall of the commutator and can rotate relative to the commutator, and the commutator is characterized in that the commutator is the commutator provided according to the first aspect of the present application.

[0019] In at least one embodiment, the rotor is a coreless rotor including windings but not an iron core.

[0020] 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

[0021] Figure 1 It is a schematic diagram of a partial structure of a coreless motor including a commutator in the prior art.

[0022] Figure 2 is a schematic diagram of a commutator according to one embodiment of the present application.

[0023] Figure 33 is a schematic diagram of adjacent commutator segments of a commutator according to one embodiment of the present application unfolded along the circumferential direction.

[0024] Figures 4 to 6 A schematic diagram showing the position of the brush as it slides between two adjacent commutator segments.

[0025] Figures 7 to 9 3 is a schematic diagram of the commutator segment structure of three variations of the commutator according to the present application unfolded along the circumferential direction.

[0026] Description of reference numerals:

[0027] R rotor; 10 commutator; 11 commutator segment; 111 protrusion; 112 recess; 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

[0028] The following describes exemplary embodiments of the present invention 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 embodiments of the present invention, nor to limit the scope of the present invention.

[0029] 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.

[0030] Reference Figure 2 The commutator 10 of this embodiment includes a cylindrical main body 13 and a plurality of commutator segments 11 surrounding the outer circumference of the main body 13. Adjacent commutator segments 11 are spaced apart in the circumferential direction C to form slots 12. The most significant difference between this embodiment and the prior art is that the slots 12 do not extend completely flush with the axial direction A, but instead extend in a zigzag manner relative to the axial direction.

[0031] Figure 3 A simplified schematic diagram shows two circumferentially adjacent commutator segments 11 unfolded along the circumferential direction C. The diagram specifically illustrates the structure of the adjacent edges of the two commutator segments 11, omitting the specific structure of the circumferentially diverging edges (which are simplified by arranging them parallel to the axial direction). The number of protrusions 111 and recesses 112 shown in the diagram does not represent the actual number of protrusions and recesses on each commutator segment, nor does the proportional relationship between the various structures in the diagram represent the proportional relationship between specific parts of the actual commutator segments.

[0032] The zigzag 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.

[0033] 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 of these auxiliary lines satisfies the requirement that, regardless of where the auxiliary line is located on the circumferential direction C within the slot 12, the auxiliary line will pass through at least one commutator segment 11. The "passing" mentioned here includes contact with the interior of the commutator segment 11 and also includes contact with 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.

[0034] 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 arrows in the figure show the sliding direction of the brush 20 relative to the commutator segment 11.

[0035] 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 protrusion 111 still has a partial supporting effect on the brush 20.

[0036] Figure 5 The figure shows a state where the brush 20 moves further away from the upper commutator segment 11 and partially touches the lower commutator segment 11. During this process, the protrusion of the upper commutator segment 11 continues to support the brush 20, and the area of the protrusion of the lower commutator segment 11 supporting the brush 20 is further increased.

[0037] 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.

[0038] As can be seen from the above process, according to the commutator of this embodiment, the brush 20 is continuously, dynamically, and partially supported near the slot 12 throughout the entire process of sliding from one commutator segment 11 to the adjacent commutator segment 11. The radial support provided by the commutator segment 11 for the brush 20 is far greater than that of the prior art described above. As a result, radial runout of the brush 20 is reduced, minimizing NVH issues in the motor and slowing wear of the brush 20.

[0039] 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.

[0040] 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.

[0041] 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 staggered in the axial direction, so that when the brush 20 passes through the slot 12, the supporting force at all locations in the axial direction is more uniform.

[0042] Figure 7 A variation of this embodiment is shown. In this variation, the size of the protrusion 111 in the axial direction A gradually decreases as the brush (not shown) leaves the commutator segment 11 in the circumferential direction C, i.e., the direction indicated by the hollow arrow for the upper commutator segment 11 in the figure. Alternatively, the size of the protrusion 111 in the axial direction A gradually increases as the brush enters the commutator segment 11 in the circumferential direction, i.e., the direction indicated by the hollow arrow for the lower commutator segment 11 in the figure. This structure ensures that the contact area between the brush and the commutator segment 11 decreases and increases uniformly as the brush passes through the slot 12, thereby effectively reducing radial runout of the brush 20, making current changes more stable, and thus reducing sparking.

[0043] Figure 8Another variation of this embodiment is shown. In this variation, the width of the slots 12 in the circumferential direction C is further reduced, and adjacent protrusions 111 have overlapping regions G in the circumferential direction C. This increases the probability or duration of support for the brushes by the protrusions 111 as they pass through the slots 12, thereby further reducing radial runout of the brushes 20 and stabilizing current changes, thereby reducing sparking.

[0044] Figure 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.

[0045] It should be understood that the above-mentioned embodiments and some aspects or features thereof may be appropriately combined.

[0046] The present application also provides a DC motor comprising the aforementioned commutator, wherein the rotor of the DC motor may be a hollow cup rotor having windings but no iron core.

[0047] Of course, the present invention is not limited to the above embodiments. Those skilled in the art can make various modifications to the above embodiments 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 slots (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). Any auxiliary line parallel to the axial direction (A) is made in the groove (12), and the auxiliary line passes through at least one of the commutator segments (11). Each of the commutator segments (11) is formed with a plurality of protrusions (111) and a plurality of recesses (112) facing the other commutator segment (11) adjacent in the circumferential direction. The protrusions (111) of one of the two commutator segments (11) adjacent in the circumferential direction and the recesses (112) of the other are aligned in the axial direction.

2. The commutator according to claim 1, characterized in that During the translation of the auxiliary line along the circumferential direction (C) in the slot (12), there is a position where the auxiliary line passes through two commutator segments (11) at the same time.

3. The commutator according to claim 1, characterized in that The number of protrusions (111) on each commutator segment (11) is equal.

4. The commutator according to claim 1, characterized in that The convex portion (111) on each commutator segment (11) has the same shape.

5. The commutator according to claim 1, 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.

6. The commutator according to claim 1, characterized in that Each of the grooves (12) has a centrally symmetrical shape.

7. A DC 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 attached to 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 6.

8. The DC motor according to claim 7, characterized in that: The rotor is a hollow cup rotor (R) including windings but not an iron core.

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