Angle grinder and its motor

Abstract

The present invention discloses an angle grinder and its motor. The angle grinder includes: a housing; an output shaft; a motor; the motor includes: a stator assembly; a rotor assembly including a motor shaft rotatable about a first axis; a commutator; and carbon brushes. The commutator includes: a bushing for connecting the commutator to the motor shaft; a plurality of commutator segments arranged sequentially in a circumferential direction around the first axis, the plurality of commutator segments surrounding the bushing; an insulating member for combining the bushing and the commutator segments so that they form a whole; the commutator segments include: a contact portion for contacting the carbon brush; a coupling portion for coupling the commutator segments to the insulating member; and a connecting portion connecting the contact portion and the coupling portion. The contact portion and the coupling portion are spaced apart in a radial direction perpendicular to the first axis. The difference between the length of the contact portion in a direction parallel to the first axis and the length of the coupling portion in a direction parallel to the first axis is greater than or equal to 0 mm and less than or equal to 2 mm. The angle grinder has a high motor speed and a long service life.

Description

Technical Field

[0001] The invention relates to an electric tool, in particular to an angle grinder and a motor thereof. Background Art

[0002] Angle grinders are high-power power tools, and their complex operating conditions necessitate the use of high-power, high-speed, series-wound motors. As a key component of high-power series-wound motors, the commutator's strength and performance are crucial for stable operation. At high speeds, the commutator must withstand the immense centrifugal forces generated by the motor. Otherwise, the commutator segments will shift radially due to the centrifugal force, or even detach from the commutator's base. Summary of the Invention

[0003] In order to solve the deficiencies of the prior art, the present invention aims to provide a high-speed angle grinder with a long service life.

[0004] In order to achieve the above objectives, the present invention adopts the following technical solutions:

[0005] An angle grinder comprises: a housing; an output shaft, at least partially extending out of the housing; a motor, for driving the output shaft to output power; the motor comprises: a stator assembly; a rotor assembly, comprising a motor shaft rotatable around a first axis; a commutator, connected to the motor shaft; a carbon brush, in contact with the commutator; wherein the commutator comprises: a bushing, for connecting the commutator to the motor shaft; a plurality of commutator segments, arranged in sequence in a circumferential direction around the first axis, with the plurality of commutator segments surrounding the bushing; an insulating member, for combining the bushing and the commutator segments so that they form a whole; the commutator segments comprise: a contact portion, for contacting the carbon brush; a coupling portion, for coupling the commutator segments to the insulating member; a connecting portion, connecting the contact portion and the coupling portion; the contact portion and the coupling portion are spaced apart in a radial direction perpendicular to the first axis; the difference between the length of the contact portion in a direction parallel to the first axis and the length of the coupling portion in a direction parallel to the first axis is greater than or equal to 0 mm and less than 2 mm.

[0006] Optionally, a difference between a length of the contact portion in a direction parallel to the first axis and a length of the coupling portion in a direction parallel to the first axis is greater than or equal to 0 mm and less than or equal to 1 mm.

[0007] Optionally, a difference between a length of the contact portion in a direction parallel to the first axis and a length of the coupling portion in a direction parallel to the first axis is greater than or equal to 0 mm and less than or equal to 0.5 mm.

[0008] Optionally, in a direction parallel to the first axis, the coupling portion includes a first end and a second end disposed at both ends, and the contact portion includes a third end and a fourth end disposed at both ends; the first end and the third end are aligned, and the second end and the fourth end are aligned.

[0009] Optionally, the joining portion is continuous from the first end to the second end, and the contact portion is continuous from the third end to the fourth end.

[0010] Optionally, the number of the connecting parts is 2, an accommodating hole is formed between the two connecting parts, and the insulating member is partially embedded in the accommodating hole.

[0011] Optionally, a dimension of the accommodating hole in a direction parallel to the first axis is greater than or equal to 2.8 mm and less than or equal to 3.3 mm.

[0012] Optionally, a first accommodating groove and a second accommodating groove are further provided between the coupling portion and the contact portion, and the two connecting portions are respectively the first connecting portion and the second connecting portion, the first connecting portion is provided between the first accommodating groove and the accommodating hole, and the second connecting portion is provided between the accommodating hole and the second accommodating groove; the commutator also includes a first reinforcement ring at least partially provided in the first accommodating groove and a second reinforcement ring at least partially provided in the second accommodating groove, the first reinforcement ring surrounds the coupling portion with the first axis as the center, and the second reinforcement ring surrounds the coupling portion with the first axis as the center.

[0013] Optionally, the coupling portion includes a first supporting surface for contacting the first reinforcement ring, and a dimension of the first supporting surface in a direction parallel to the first axis is greater than or equal to 2.5 mm and less than or equal to 3.5 mm.

[0014] Optionally, the first connecting portion includes a first connecting surface and a second connecting surface, the first connecting surface constitutes the bottom of the first accommodating groove, the second connecting surface constitutes the hole wall of the accommodating hole, and the first connecting surface extends in a first plane obliquely intersecting the first axis.

[0015] Optionally, the first supporting surface extends in a second plane, the second plane is parallel to the first axis, and an angle formed by the intersection of the second plane and the first plane is greater than or equal to 75 degrees and less than or equal to 85 degrees.

[0016] Optionally, the coupling portion has a first side and a second side on both sides in the circumferential direction around the first axis, the first side is formed with a first groove recessed toward the second side, the second side is formed with a second groove recessed toward the first side, the insulating part is partially embedded in the first groove, and the insulating part is partially embedded in the second groove.

[0017] Optionally, the coupling portion extends along a first linear direction parallel to the first axis, and the contact portion extends along a second linear direction, and the second linear direction and the first linear direction are parallel to each other.

[0018] A motor comprises: a stator assembly; a rotor assembly comprising a motor shaft rotatable about a first axis; a commutator connected to the motor shaft; a carbon brush in contact with the commutator; wherein the commutator comprises: a bushing for connecting the commutator to the motor shaft; a plurality of commutator segments arranged in sequence in a circumferential direction around the first axis, the plurality of commutator segments surrounding the bushing; an insulating member for combining the bushing and the commutator segments so that they form a whole; the commutator segments comprise: a contact portion for contacting the carbon brush; a coupling portion for coupling the commutator segments to the insulating member; a connecting portion connecting the contact portion and the coupling portion; the contact portion and the coupling portion are spaced apart in a radial direction perpendicular to the first axis; the difference between the length of the contact portion in a direction parallel to the first axis and the length of the coupling portion in a direction parallel to the first axis is greater than or equal to 0 mm and less than or equal to 2 mm.

[0019] The benefits of the present invention are that the length of the coupling portion is substantially the same as the length of the contact portion, thereby increasing the contact area between the commutator segments and the insulating member, thereby increasing the coupling force between the commutator segments and the insulating member, and preventing the commutator segments from jumping in the radial direction when the motor rotates at high speed, thereby allowing the motor to rotate at high speed for a long time, thereby increasing the service life of the angle grinder, and because the motor can rotate at high speed, optimizing the output performance of the angle grinder. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a perspective view of an angle grinder as an embodiment;

[0021] Figure 2 yes Figure 1 A three-dimensional diagram of the motor of the angle grinder;

[0022] Figure 3 yes Figure 2 A three-dimensional diagram of the rotor assembly of the motor when the carbon brushes are installed;

[0023] Figure 4 yes Figure 3 A three-dimensional diagram of the commutator of the motor;

[0024] Figure 5 yes Figure 3 A plan view of the commutator of the motor;

[0025] Figure 6 yes Figure 3 Exploded diagram of the commutator of the motor;

[0026] Figure 7 yes Figure 4 A cross-sectional view of the commutator of the motor along line AA;

[0027] Figure 8 yes Figure 4 Cross-sectional view of the motor commutator along line BB

[0028] Figure 9 yes Figure 4 Cross-sectional view of the motor commutator along line CC

[0029] Figure 10 yes Figure 4 Cross-sectional view of the motor commutator along line DD

[0030] Figure 11 yes Figure 6 A three-dimensional diagram of the commutator segments of the commutator;

[0031] Figure 12 yes Figure 11 Plan view of the commutator segments in . DETAILED DESCRIPTION

[0032] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0033] Figure 1 The electric tool shown is specifically an angle grinder 100, which can grind or cut a workpiece when a grinding disc is installed. Figure 1 and Figure 2 As shown, the angle grinder 100 includes a housing 10, an output shaft 20, and a motor 30. For other types of power tools besides angle grinders, the power tool may include some other type of output component, so that the motor can drive the output component to output power. The power tool may be another type of grinding tool, such as a sander, where the output component may be a base plate. The power tool may also be a torque-generating power tool, such as an electric drill, screwdriver, or wrench. The power tool may also be a gardening power tool, such as a hair dryer, pruner, or lawn mower.

[0034] The housing 10 of the angle grinder 100 extends substantially along a straight line, and the housing 10 forms a handle for a user to hold.

[0035] The output shaft 20 at least partially extends out of the housing 10. The output shaft 20 can rotate relative to the housing 10 about the rotation axis 101. A grinding wheel can be mounted on the output shaft 20. When the output shaft 20 rotates at high speed, the grinding wheel can be driven to grind the workpiece. The motor 30 is used to drive the output shaft 20 to rotate and output power. The motor 30 can be a series motor. Figure 2 and Figure 3As shown, the motor 30 includes a stator assembly 31, a rotor assembly 32, and carbon brushes 50. The stator assembly 31 includes a stator core 311 and a stator winding 312. The stator core 311 surrounds the rotor assembly 32, and the stator winding 312 is wound around the stator core 311. The rotor assembly 32 includes a rotor core 321, a rotor winding 322, a commutator 40, and a motor shaft 323. The rotor core 321 surrounds the motor shaft 323, the rotor winding 322 is wound around the rotor core 321, and the commutator 40 is mounted on the motor shaft 323. The motor shaft 323 is rotatable about the first axis 102. When the motor shaft 323 rotates about the first axis 102, the motor 30 outputs power and drives the output shaft 20 to rotate about the rotation axis 101.

[0036] like Figure 3 As shown, the commutator 40 is mounted on the motor shaft 323 and rotates synchronously with the motor shaft 323. A plurality of carbon brushes 50 surround the commutator 40 in the circumferential direction of the commutator 40. The carbon brushes 50 are fixed relative to the stator assembly 31, so that the commutator 40, which rotates synchronously with the rotor assembly 32, can rotate relative to the carbon brushes 50. The carbon brushes 50 are electrically connected to the rotor winding 322 through the commutator 40.

[0037] like Figures 4 to 6 As shown, the commutator 40 includes a bushing 41 , a reinforcement ring 42 , an insulating member 43 and a commutator segment 44 .

[0038] The bushing 41 is arranged around the first axis 102 and is centered on the first axis 102. The number of commutator segments 44 is greater than 2. A plurality of commutator segments 44 are evenly distributed on the circumference around the first axis 102, and a plurality of commutator segments 44 are also evenly distributed around the bushing 41. There is a gap between two adjacent commutator segments 44, and the gap is filled with insulating materials. After molding, these insulating materials form an insulating part 43 for supporting the bushing 41, the commutator segments 44 and the reinforcement ring 42. On the one hand, the insulating part 43 can be used to fix the position of each commutator segment 44, and also to connect the commutator segment 44, the bushing 41 and the reinforcement ring 42 so that they form an inseparable whole; on the other hand, the insulating part 43 is partially arranged between two adjacent commutator segments 44 to achieve insulation between each commutator segment 44.

[0039] The bushing 41 is a metal part, and the bushing 41 is interference fit with the motor shaft 323 , so that the commutator 40 and the motor shaft 323 rotate synchronously.

[0040] like Figures 6 to 10As shown, the insulating member 43 is used to combine the bushing 41, multiple commutator segments 44 and the reinforcement ring 42 so that they form a whole. The insulating member 43 includes a first insulating layer 431, which is an annular insulating layer. The first insulating layer 431 is arranged between the commutator segments 44 and the bushing 41, that is, the first insulating layer 431 surrounds the bushing 41, thereby insulating the bushing 41 from the commutator segments 44. If the first insulating layer 431 is directly connected to the motor shaft 323, the insulating member 43 will be subjected to uneven stress. However, the bushing 41 is connected to the motor shaft 323, and the bushing 41 is a metal member, so that the bushing 41 is subjected to balanced stress. The outer wall of the bushing 41 is also formed with an annular groove 411 and a linear groove 412. The annular groove 411 surrounds the first axis 102, and the linear groove 412 extends in a direction parallel to the first axis 102. The inner wall of the first insulating layer 431 is embedded in the annular groove 411 , and the inner wall of the first insulating layer 431 is also embedded in the linear groove 412 , thereby improving the bonding force between the insulating member 43 and the bushing 41 and preventing the commutator 40 from failing during high-speed rotation.

[0041] The commutator segments 44 are spaced apart in a circumferential direction around the first axis 102. The insulating member 43 includes a spacer 432 that is embedded in the gap between two adjacent commutator segments 44. The spacer 432 can maintain a substantially constant spacing between the two adjacent commutator segments 44 and can also insulate the two adjacent commutator segments 44 from each other.

[0042] The commutator segment 44 includes a coupling portion 441 , a contact portion 442 , and two connecting portions, a first connecting portion 443 a and a second connecting portion 443 b , which are used to connect the coupling portion 441 and the contact portion 442 .

[0043] The coupling portion 441 is used to couple the commutator segment 44 to the insulating member 43. The coupling portion 441 is continuous and uninterrupted along the first axis 102. In other words, there is no gap on the coupling portion 441 that would cause it to be broken along the first axis 102. The contact portion 442 is used to enable the commutator 40 to contact the carbon brush 50, thereby achieving commutation. The carbon brush 50 is disposed on the outer surface of the contact portion 442 and contacts the outer surface of the contact portion 442. In a radial direction perpendicular to the first axis 102, the coupling portion 441 is disposed on the inner side of the contact portion 442. In a radial direction perpendicular to the first axis 102, the coupling portion 441 and the contact portion 442 are spaced apart.

[0044] like Figures 7 to 12As shown, the coupling portion 441 has a first end 441a and a second end 441b along the first axis 102, and the first end 441a and the second end 441b are continuous. In other words, the coupling portion 441 does not have a gap separating the first end 441a and the second end 441b in the direction of the first axis 102. The contact portion 442 has a third end 442a and a fourth end 442b along the first axis 102, and the third end 442a and the fourth end 442b are continuous. In other words, the contact portion 442 does not have a gap separating the third end 442a and the fourth end 442b in the direction of the first axis 102.

[0045] The difference between the length of the coupling portion 441 along the first axis 102 and the length of the contact portion 442 along the first axis 102 is greater than or equal to 0 mm and less than 2 mm. That is, the difference between the distance L1 between the first end 441a and the second end 441b and the distance L2 between the third end 442a and the fourth end 442b is greater than or equal to 0 mm and less than 2 mm. On the one hand, the length of the coupling portion 441 can be increased, thereby increasing the contact area between the coupling portion 441 and the insulating member 43, improving the bonding force between the coupling portion 441 and the insulating member 43, and between the reinforcing ring 42 and the insulating member 43. This can prevent the commutator segments 44 from changing their radial position when the commutator 40 rotates at high speed with the motor 30, thereby extending the service life of the commutator segments 44 and allowing the motor 30 to rotate at high speed to increase the maximum speed of the motor 30. Ultimately, this can enable the power tool to output a higher speed, improve work efficiency, and achieve better performance. On the other hand, because the length of the coupling portion 441 along the first axis 102 is sufficiently long, a sufficiently wide area is formed between the coupling portion 441 and the contact portion 442 along the first axis 102. This area can be used to accommodate the reinforcement ring 42. The reinforcement ring 42 does not protrude beyond the coupling portion 441 and the contact portion 442 along the first axis 102, thereby preventing the reinforcement ring 42 from separating from the commutator segments 44 along the first axis 102. Moreover, the contact area between the reinforcement ring 42 and the coupling portion 441 is also increased, thereby improving the position-limiting effect on the commutator segments 44 and preventing the commutator segments 44 from flying out due to centrifugal force when the commutator 40 rotates at high speed with the motor 30.

[0046] In this embodiment, all lengths, dimensions, and other dimensions are subject to tolerance. For example, in this embodiment, the tolerance is 0.05 mm, and the distance between the first end 441a and the second end 441b is L1. Therefore, due to the tolerance, a distance actually measured between the first end 441a and the second end 441b of L1 + 0.05 mm is considered to be L1. Similarly, a distance actually measured between the first end 441a and the second end 441b of L1 - 0.05 mm is considered to be L1. Other dimensions, such as L2, the dimension of the receiving hole parallel to the first axis, and the dimension of the first support surface parallel to the first axis, are also subject to tolerance.

[0047] The difference between the length of the coupling portion 441 along the first axis 102 and the length of the contact portion 442 along the first axis 102 may also be greater than or equal to 0 mm and less than or equal to 1.5 mm. The difference between the length of the coupling portion 441 along the first axis 102 and the length of the contact portion 442 along the first axis 102 may also be greater than or equal to 0 mm and less than or equal to 1 mm. The difference between the length of the coupling portion 441 along the first axis 102 and the length of the contact portion 442 along the first axis 102 may also be greater than or equal to 0 mm and less than or equal to 0.5 mm. Most preferably, the difference between the length of the coupling portion 441 along the first axis 102 and the length of the contact portion 442 along the first axis 102 is equal to 0 mm. In other words, the length of the coupling portion 441 along the first axis 102 and the length of the contact portion 442 along the first axis 102 are substantially the same. In other words, the first end 441a and the third end 442a are aligned, and the second end 441b and the fourth end 442b are aligned. In this way, on the one hand, the length of the coupling portion 441 can be further increased, thereby increasing the contact area between the coupling portion 441 and the insulating member 43 and improving the bonding force between the coupling portion 441 and the insulating member 43. This can prevent the commutator 40 from changing its radial position when the motor 30 rotates at high speed. This can extend the service life of the commutator segments 44 and allow the motor 30 to rotate at high speed to increase the maximum speed of the motor 30. Ultimately, it can enable the power tool to output a higher speed, improve work efficiency, and achieve better performance. On the other hand, because the coupling portion 441 is sufficiently long along the first axis 102, a sufficiently wide area is formed between the coupling portion 441 and the contact portion 442 along the first axis. This area can be used to accommodate the reinforcement ring 42. The reinforcement ring 42 does not protrude from the coupling portion 441 and the contact portion 442 along the first axis 102, thereby preventing the reinforcement ring 42 from separating from the commutator segments 44 along the first axis 102. Moreover, the contact area between the reinforcement ring 42 and the joint 441 is also increased, thereby improving the limiting effect on the commutator segment 44 and preventing the commutator segment 44 from flying out due to the centrifugal force when the commutator 40 rotates at high speed with the motor 30.

[0048] The length of the connecting portion 441 along the first axis 102 is greater than or equal to 10 mm and less than or equal to 20 mm. Furthermore, the length of the connecting portion 441 along the first axis 102 is greater than or equal to 12 mm and less than or equal to 20 mm.

[0049] The coupling portion 441 extends along the first straight line 103, and the contact portion 442 extends along the second straight line 104. The first straight line 103 and the second straight line 104 are parallel to each other, and the first straight line 103 is also parallel to the first axis 102. In a radial direction perpendicular to the first axis 102, the coupling portion 441 and the contact portion 442 are separated by a certain distance. The first connecting portion 443a and the second connecting portion 443b connect the coupling portion 441 and the contact portion 442 so that the coupling portion 441 and the contact portion 442 form a single unit. In this embodiment, the coupling portion 441, the contact portion 442, and the first connecting portion 443a and the second connecting portion 443b are integrally formed.

[0050] The contact portion 442 has an L-shaped structure, so that the commutator 40 can be a slot-type commutator or a hook-type commutator. In other words, a conductive portion 442c is formed at the fourth end 442b of the contact portion 442. The conductive portion 442c is used to connect to the rotor winding 322.

[0051] The first connecting portion 443a and the second connecting portion 443b are connected to the joint portion 441 and the contact portion 442 respectively. A certain distance is separated between the first connecting portion 443a and the second connecting portion 443b to form an accommodating hole 444a, in which a part of the insulating member 43 can be accommodated. Figure 7 and Figure 9 As shown, the portion of the insulating member 43 embedded in the receiving hole 444a is distributed in a circumferential direction around the first axis 102. The insulating member 43 includes an annular portion 433, which includes an embedded portion 433a embedded in the receiving hole 444a and a portion disposed between two adjacent receiving holes 444a. Thus, on the one hand, the embedded portion 433a of the annular portion 433 embedded in the receiving hole 444a can increase the contact area between the insulating member 43 and the commutator segment 44, thereby improving the bonding force between the commutator segment 44 and the insulating member 43. On the other hand, the annular portion 433 itself is a retaining ring surrounding the commutator segment 44, which can further limit the radial position of the commutator segment 44, thereby preventing the commutator segment 44 from radially separating from the insulating member 43 and reducing radial position fluctuation of the commutator segment 44 when the motor 30 rotates at high speed.

[0052] In this embodiment, because the length of the coupling portion 441 along the first axis 102 is substantially the same as the length of the contact portion 442 along the first axis 102, the coupling portion 441 is sufficiently long. This allows the first connecting portion 443a to be closer to the first end 441a of the coupling portion 441, and the second connecting portion 443b to be closer to the second end 441b of the coupling portion 441. This further increases the length of the receiving hole 444a along the first axis 102. The length of the receiving hole 444a along the first axis 102 is greater than 2.6 mm and less than or equal to 3.5 mm. Optionally, the length of the receiving hole 444a along the first axis 102 is greater than or equal to 2.8 mm and less than or equal to 3.3 mm. The ratio of the length of the receiving hole 444a along the first axis 102 to the length of the contact portion 442 along the first axis 102 is greater than or equal to 0.17 and less than or equal to 0.22. In this way, the length of the accommodating hole 444a along the first axis 102 is increased, thereby improving the bonding force between the commutator segment 44 and the insulating part 43, and can further reduce the radial position jump of the commutator segment 44 when the motor 30 rotates at high speed, and can also effectively reduce the deformation of the commutator segment 44.

[0053] A first receiving groove 444b and a second receiving groove 444c are further formed between the coupling portion 441 and the contact portion 442. The first receiving groove 444b is located on a side of the first connecting portion 443a away from the receiving hole 444a, while the second receiving groove 444c is located on a side of the second connecting portion 443b away from the receiving hole 444a. The first connecting portion 443a is located between the first receiving groove 444b and the receiving hole 444a, while the second connecting portion 443b is located between the second receiving groove 444c and the receiving hole 444a. The first receiving groove 444b opens in a direction parallel to the first axis 102, away from the first connecting portion 443a. The second receiving groove 444c opens in a direction parallel to the first axis 102, away from the second connecting portion 443b. There are two reinforcement rings 42, one disposed within the first receiving groove 444b and the other within the second receiving groove 444c. This allows the reinforcement rings 42 to surround the coupling portion 441 centered on the first axis 102. Because the coupling portion 441 is sufficiently long along the first straight line 103, the length of the first receiving groove 444b parallel to the first axis 102 is increased, while the length of the second receiving groove 444c along the first axis 102 is increased. This provides sufficient space for the reinforcement rings 42, increasing the contact area between the reinforcement rings 42 and the coupling portion 441. The coupling portion 441 includes a first support surface 441c and a second support surface 441d for supporting the reinforcement rings 42. The first support surface 441c is disposed on the side of the first connecting portion 443a away from the second connecting portion 443b, and the second support surface 441d is disposed on the side of the second connecting portion 443b away from the first connecting portion 443a. The length of the first support surface 441c in a direction parallel to the first axis 102 is greater than or equal to 2 mm and less than or equal to 4 mm, and the length of the second support surface 441d in a direction parallel to the first axis 102 is greater than or equal to 2 mm and less than or equal to 4 mm. In some embodiments, the length of the first support surface 441c in a direction parallel to the first axis 102 is greater than or equal to 2.5 mm and less than or equal to 3.5 mm, and the length of the second support surface 441d in a direction parallel to the first axis 102 is greater than or equal to 2.5 mm and less than or equal to 3.5 mm. In this way, the dimensions of the first support surface 441c and the second support surface 441d are large enough to achieve reliable contact with the reinforcement ring 42, further improving the reinforcement ring 42's limiting effect on the commutator segment 44.

[0054] The coupling portion 441 has a first side 441e and a second side 441f on either side of the coupling portion 441e along the circumference of the first axis 102. The first side 441e is provided with a first groove 441g that is recessed toward the second side 441f, and the second side 441f is provided with a second groove 441h that is recessed toward the first side 441e. The first groove 441g extends from the first end 441a to the second end 441b. The second groove 441h extends from the first end 441a to the second end 441b. Thus, the insulating member 43 is partially embedded in the first groove 441g and the second groove 441h. Specifically, the insulating member 43 includes a first protrusion 434 that is embedded in the first groove 441g and a second protrusion 435 that is embedded in the second groove 441h. The contact between the first groove 441g and the first protrusion 434, and the contact between the second groove 441h and the second protrusion 435, further increases the contact area between the coupling portion 441 and the insulating member 43, thereby enhancing the coupling force between the commutator segment 44 and the insulating member 43. Furthermore, the first protrusion 434 and the second protrusion 435 are both embedded in the coupling portion 441. Thus, the first protrusion 434 and the second protrusion 435 radially generate a stopping force that prevents the coupling portion 441 from moving radially away from the first axis 102, and the second protrusion 435 radially generates a stopping force that prevents the coupling portion 441 from moving radially away from the first axis 102. The first groove 441g is an arcuate groove, and the second groove 441h is also an arcuate groove.

[0055] The first connecting portion 443a has a third side 443c and a fourth side 443d on either side along the circumference of the first axis 102. A third protrusion 443e is provided on the third side 443c, and a fourth protrusion 443f is provided on the fourth side 443d. In this way, the insulating member 43 is partially embedded in the area between the third protrusion 443e and the coupling portion 441, and can also be embedded in the area between the third protrusion 443e and the contact portion. Similarly, the insulating member 43 can also be embedded in the area between the fourth protrusion 443f and the coupling portion 441, and can also be embedded in the area between the fourth protrusion 443f and the contact portion. Specifically, the insulating member 43 includes a third groove 436 that allows the third protrusion 443e to be embedded, and a fourth groove 437 that allows the fourth protrusion 443f to be embedded. The contact between the third protrusion 443e and the third groove 436, and the contact between the fourth protrusion 443f and the fourth groove 437, further increases the contact area between the coupling portion 441 and the insulating member 43, thereby increasing the coupling force between the commutator segment 44 and the insulating member 43. The first connecting portion 443a and the second connecting portion 443b are symmetrically arranged about a plane perpendicular to the first axis 102.

[0056] The first connecting portion 443a includes a first connecting surface 443g and a second connecting surface 443h. The first connecting surface 443g also forms the bottom of the first receiving groove 444b, and the second connecting surface 443h forms the wall of the receiving hole 444a. The first connecting surface 443g extends substantially along the first plane 105, which intersects the first axis 102 at an angle. The second connecting surface 443h is substantially perpendicular to the first axis 102. The first supporting surface 441c of the joint 441 extends within the second plane 106. The angle A1 formed by the intersection of the second plane 106 and the first plane 105 is greater than or equal to 75 degrees and less than or equal to 85 degrees. Furthermore, the angle A1 formed by the intersection of the second plane 106 and the first plane 105 is 80 degrees. The contact portion 442 is formed with a third support surface 442d for supporting the reinforcement ring 42. The third support surface 442d extends within the third plane 107. The angle A2 formed by the intersection of the third plane 107 and the first plane 105 is greater than or equal to 105 and less than or equal to 115. Furthermore, the angle A2 formed by the intersection of the third plane 107 and the first plane 105 is 100 degrees. This not only increases the bonding force between the insulating member 43 and the commutator segment 44, but also enables the bonding force to have a component along the first axis 102, thereby effectively reducing the runout or deformation of the commutator segment 44 along the first axis 102. The first connecting surface 443g can also be a circular arc surface, and the second connecting surface 443h can also be a circular arc surface.

[0057] The third protrusion 443e extends from the first connecting surface 443g to the second connecting surface 443h, and the fourth protrusion 443f also extends from the first connecting surface 443g to the second connecting surface 443h.

[0058] In addition, simulation tests were conducted on the model of the commutator segment in this embodiment and models of some existing commutator segment samples, and comparisons were made to conclude that the commutator segment in this embodiment has better performance, as detailed below.

[0059] Table 1:

[0060]

[0061]

[0062] Table 1 above simulates and measures the peak stress and total deformation at the third end of the contact portion of the commutator segment model, and also simulates and measures the peak stress and total deformation at the fourth end of the contact portion. In the commutator segment of Model 1, the length of the joint portion is shorter than the length of the contact portion, and the joint portion is not provided with the first and second grooves, nor is the third and fourth protrusions provided on the connecting portion. The commutator segment in Model 2 is improved on the basis of the commutator segment of Model 1, with the first and second grooves provided on the joint portion, and the third and fourth protrusions provided on the connecting portion. The commutator segment of Model 3 is a further improvement on the commutator segment of Model 2, so that the first connecting edge of the connecting portion extends along the first plane obliquely intersecting the first axis. The commutator segment of Model 4 is a further improvement on the commutator segment of Model 3, with the length of the joint portion along the first axis increased, and the length of the joint portion is substantially the same as the length of the base portion. Compared to the commutator segments of Model 1, the commutator segments of Model 2 have additional first and second grooves, as well as third and fourth protrusions. The simulation results clearly show that the peak stress of Model 2 is significantly lower than that of Model 1, and the total deformation of Model 2 is also significantly lower than that of Model 1. Compared to the commutator segments of Model 3, the commutator segments of Model 4 have increased the length of the joint and made the length of the joint substantially the same as the length of the contact portion. The simulation results clearly show that the peak stress of Model 4 is significantly lower than that of Model 3, and the total deformation of Model 4 is also significantly lower than that of Model 3. Furthermore, the simulation results clearly show that the tilting of the first connecting surface relative to the first axis and the increase in the length of the receiving hole can also improve the performance of the commutator segments and reduce their deformation.

[0063] Table 2:

[0064]

[0065] Table 2 above tests the inter-segment step difference and radial runout of the commutator during high-temperature and high-speed rotation. Inter-segment step difference refers to the following: the position change of the first commutator segment along the radial direction perpendicular to the first axis during high-speed rotation is the first commutator segment; the position change of the second commutator segment along the radial direction perpendicular to the first axis during high-speed rotation is the second change; the difference between the first commutation quantity and the second change is the inter-segment step difference of the two commutator segments; the maximum inter-segment step difference among all commutator segments is the maximum inter-segment step difference of the commutator. Radial variation refers to the radial variation of the change in the radial direction perpendicular to the first axis during high-speed rotation. Sample 1 is a commutator segment in the prior art, in which the length of the joint portion of the commutator segment is less than the length of the contact portion, the joint portion is not provided with a groove, and the connecting portion is not provided with a protrusion; Sample 2 is the commutator in this embodiment. The test results in Table 2 show that the inter-segment step difference of the commutator in Sample 1 is 2.452, while the inter-segment step difference of the commutator in this embodiment is 1.61. This represents a 34.34% reduction compared to the inter-segment step difference of the commutator in the prior art. The radial variation of the commutator in Sample 1 is 4.44, while the radial variation of the commutator in this embodiment is 2.602. This represents a 41.40% reduction compared to the radial variation of the commutator in the prior art. The above comparison shows that the commutator in this embodiment exhibits less radial positional variation of the commutator segments during high-speed motor rotation, thereby extending the commutator's service life, allowing the motor to operate at high speeds for extended periods, and thus improving the output performance of the power tool.

[0066] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the above embodiments do not limit the present invention in any form, and any technical solutions obtained by equivalent replacement or equivalent transformation fall within the scope of protection of the present invention.

Claims

1. An angle grinder, comprising: case; an output shaft, at least partially extending outside the housing; A motor, used to drive the output shaft to output power; The motor comprises: stator assembly; a rotor assembly comprising a motor shaft rotatable about a first axis; a commutator connected to the motor shaft; a carbon brush in contact with the commutator; Wherein, the commutator comprises: A bushing, used to connect the commutator to the motor shaft; an outer wall of the bushing is formed with an annular groove and a linear groove; A plurality of commutator segments are sequentially arranged in a circumferential direction around the first axis, and the plurality of commutator segments surround the bushing; an insulating member, used to combine the bushing and the commutator segment so that they form a whole; the insulating member includes a first insulating layer, the inner wall of the first insulating layer is embedded in the annular groove and the linear groove; Its characteristics are: The commutator segment comprises: A contact portion, configured to contact the carbon brush; a coupling portion, used for coupling the commutator segment to the insulating member; a connecting portion connecting the contact portion and the combining portion; The contact portion and the coupling portion are spaced apart in a radial direction perpendicular to the first axis; A difference between a length of the contact portion in a direction parallel to the first axis and a length of the coupling portion in a direction parallel to the first axis is greater than or equal to 0 mm and less than 2 mm; In a direction parallel to the first axis, the coupling portion includes a first end and a second end provided at both ends, and the contact portion includes a third end and a fourth end provided at both ends; the first end and the third end are basically aligned, and the second end and the fourth end are basically aligned.

2. The angle grinder according to claim 1, characterized in that: A difference between a length of the contact portion in a direction parallel to the first axis and a length of the coupling portion in a direction parallel to the first axis is greater than or equal to 0 mm and less than or equal to 1 mm.

3. The angle grinder according to claim 1, characterized in that: A difference between a length of the contact portion in a direction parallel to the first axis and a length of the coupling portion in a direction parallel to the first axis is greater than or equal to 0 mm and less than or equal to 0.5 mm.

4. The angle grinder according to claim 1, characterized in that: The coupling portion is continuous from the first end to the second end, and the contact portion is continuous from the third end to the fourth end.

5. The angle grinder according to claim 4, characterized in that: The number of the connecting parts is 2, an accommodating hole is formed between the two connecting parts, and the insulating member is partially embedded in the accommodating hole.

6. The angle grinder according to claim 5, characterized in that: A dimension of the accommodating hole in a direction parallel to the first axis is greater than or equal to 2.8 mm and less than or equal to 3.3 mm.

7. The angle grinder according to claim 5, characterized in that: A first receiving groove and a second receiving groove are further provided between the coupling portion and the contact portion, and the two connecting portions are respectively a first connecting portion and a second connecting portion, the first connecting portion is provided between the first receiving groove and the receiving hole, and the second connecting portion is provided between the receiving hole and the second receiving groove; The commutator also includes a first reinforcement ring at least partially disposed in the first accommodating groove and a second reinforcement ring at least partially disposed in the second accommodating groove, the first reinforcement ring surrounds the joint with the first axis as the center, and the second reinforcement ring surrounds the joint with the first axis as the center.

8. The angle grinder according to claim 7, characterized in that: The coupling portion includes a first supporting surface for contacting the first reinforcement ring, and a dimension of the first supporting surface in a direction parallel to the first axis is greater than or equal to 2.5 mm and less than or equal to 3.5 mm.

9. The angle grinder according to claim 8, characterized in that: The first connecting portion includes a first connecting surface and a second connecting surface, the first connecting surface constitutes the bottom of the first accommodating groove, the second connecting surface constitutes the hole wall of the accommodating hole, and the first connecting surface extends in a first plane obliquely intersecting the first axis.

10. The angle grinder according to claim 9, characterized in that: The first supporting surface extends in a second plane, the second plane is parallel to the first axis, and an angle formed by the intersection of the second plane and the first plane is greater than or equal to 75 degrees and less than or equal to 85 degrees.

11. The angle grinder according to claim 5, characterized in that: The coupling portion comprises a first side and a second side on both sides in a circumferential direction around the first axis, the first side is formed with a first groove recessed toward the second side, the second side is formed with a second groove recessed toward the first side, the insulating part is partially embedded in the first groove, and the insulating part is partially embedded in the second groove.

12. The angle grinder according to claim 1, characterized in that: The coupling portion extends along a first linear direction parallel to the first axis, and the contact portion extends along a second linear direction, wherein the second linear direction is parallel to the first linear direction.

13. A motor comprising: stator assembly; a rotor assembly comprising a motor shaft rotatable about a first axis; a commutator connected to the motor shaft; a carbon brush in contact with the commutator; Wherein, the commutator comprises: A bushing, used to connect the commutator to the motor shaft; an outer wall of the bushing is formed with an annular groove and a linear groove; A plurality of commutator segments are sequentially arranged in a circumferential direction around the first axis, and the plurality of commutator segments surround the bushing; an insulating member, used to combine the bushing and the commutator segment so that they form a whole; the insulating member includes a first insulating layer, the inner wall of the first insulating layer is embedded in the annular groove and the linear groove; The commutator segment comprises: A contact portion, configured to contact the carbon brush; a coupling portion, used for coupling the commutator segment to the insulating member; a connecting portion connecting the contact portion and the combining portion; The contact portion and the coupling portion are spaced apart in a radial direction perpendicular to the first axis; A difference between a length of the contact portion in a direction parallel to the first axis and a length of the coupling portion in a direction parallel to the first axis is greater than or equal to 0 mm and less than 2 mm; In a direction parallel to the first axis, the coupling portion includes a first end and a second end provided at both ends, and the contact portion includes a third end and a fourth end provided at both ends; the first end and the third end are basically aligned, and the second end and the fourth end are basically aligned.

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