Magnetic steel structure of direct current brush motor and direct current brush motor

Abstract

This invention relates to a magnet for a DC brushed motor, comprising a magnet body with a tile-shaped structure. The two ends of the magnet body along its arc length are axially symmetrical. At least one double-sided slot and at least one single-sided slot are provided on the inner side of each end along its arc length. The double-sided slot is located at the center along the height direction of the magnet body, and the single-sided slot is located on one side along the height direction. The single-sided and double-sided slots are spaced apart along the height direction of the magnet. This invention has a theoretical basis and reduces the Fourier decomposition coefficient of the nz / 2p order by using different combinations of unequal pole arc coefficients, thus weakening the magnetic slot torque of the motor as much as possible.

Description

Technical Field

[0001] This invention relates to a magnet structure for a DC brushed motor and a DC brushed motor, belonging to the technical field of motor magnets. Background Technology

[0002] In DC brushed motors, the permanent magnets are typically regular arched shapes, with both the inner and outer arc surfaces being cylindrical. The horizontal planes at the bottom two ends are called the arch height surfaces. During operation, this type of channel steel generates significant electromagnetic noise due to factors such as cogging torque pulsation.

[0003] A noise-reducing magnetic tile for permanent magnet motors, which can effectively reduce electromagnetic noise, is disclosed in Chinese patent application document CN2691154Y. The noise-reducing magnetic tile for permanent magnet motors includes an arched base of permanent magnet material, the inner and outer arc surfaces of which are cylindrical, and the two bottom ends are horizontal arched surfaces. Several pairs of slots are opened on the inner edge of the two arched surfaces.

[0004] The magnetic tile has several pairs of slots, each pair of slots having the same structure, which makes the magnetic tile structure generate a relative pole arc coefficient combination in three-dimensional space. This results in a lower reduction in the magnetic slot torque of the motor, and thus a lower reduction in electromagnetic noise. Summary of the Invention

[0005] The purpose of this invention is to provide a magnet structure for a DC brushed motor and a DC brushed motor, which solves the problems of lack of theoretical basis and low reduction in magnetic slot torque of the motor in the existing technology.

[0006] The above-mentioned technical objective of the present invention is mainly achieved through the following technical solution: a magnet for a DC brushed motor, comprising a magnet body with a tile-shaped structure, wherein the structures at both ends of the magnet body in the arc length direction are axially symmetrical, and at least one double-sided groove and at least one single-sided groove are provided on the inner side of the end of the magnet body in the arc length direction, wherein the double-sided groove is located in the middle in the height direction of the magnet body, and the single-sided groove is located on one side in the height direction of the magnet body, wherein the single-sided groove and the double-sided groove are spaced apart in the height direction of the magnet; the double-sided groove includes two first sidewalls and a first groove bottom, and the single-sided groove includes a second sidewall and a second groove bottom; the at least one double-sided groove and at least one single-sided groove are provided on the inner side of the end of the magnet body in the arc length direction, and the double-sided groove and the single-sided groove are spaced apart from each other, thereby generating a set of unequal pole arc coefficient combinations in three-dimensional space, thereby reducing the Fourier decomposition coefficient of the nz / 2p order by the combination of unequal pole arc coefficients, thereby reducing the slot torque of the motor, improving the attenuation degree of the slot torque of the motor, and further reducing electromagnetic noise.

[0007] Preferably, the width of the double-sided groove along the arc length direction of the magnet body is between 1 / 6 and 1 / 3 of the length of the inner arc surface of the magnet; by changing the inner arc surface, the polar arc coefficient on different planes of the magnet can be changed.

[0008] Preferably, the depth of the double-sided groove is set along the thickness direction of the magnet body, and the maximum depth of the double-sided groove is greater than half the thickness of the magnet body; reducing the thickness reduces the impact of the decrease in magnetic flux on the performance of the magnet.

[0009] Preferably, the depth of the double-sided groove gradually increases from the middle of the arc length near the magnet body to both ends of the arc length of the magnet body; this facilitates the machining of the inner arc using a grinding wheel.

[0010] Preferably, the first groove bottom is formed by two inclined surfaces that are inclined along the height direction of the magnet body. The inclined surfaces are inclined from the root of the first sidewall to the joint of the two inclined surfaces from the inside to the outside in the thickness direction of the magnet body. The two inclined surfaces are joined together to form a V-shaped structure. The Fourier decomposition coefficient of the order nz / 2p is reduced by combining different polar arc coefficients.

[0011] Preferably, the double-sided slot has a single-sided slot on both the upper and lower sides in the height direction of the magnet body, and the two single-sided slot magnet bodies are symmetrically arranged in the height direction of each other; by combining different pole arc coefficients, the Fourier decomposition coefficient of the nz / 2p order is reduced, the magnet structure is further optimized, and the reduction of the magnetic slot torque is promoted.

[0012] Preferably, the double-sided groove has a single-sided groove on both the upper and lower sides in the height direction of the magnet body, and the two single-sided grooves have different depths; by combining different polar arc coefficients, the Fourier decomposition coefficient of the nz / 2p order is reduced, and different combinations of polar arc coefficients are provided according to actual use needs to increase the versatility of the solution.

[0013] Preferably, the first and second groove bottoms are composed of one or two arc-shaped surfaces; using arc-shaped surfaces makes it easier to process and shape the magnets.

[0014] Preferably, a tooth is formed between the double-sided groove and the single-sided groove; the tooth can separate the double-sided groove and the single-sided groove, so that the double-sided groove and the single-sided groove are independent of each other and can be combined with each other.

[0015] Preferably, the DC brushed motor includes a housing and a rotor that is rotatably supported between the housing and the housing. The inner wall of the housing is provided with a plurality of magnets. By opening double-sided slots and single-sided slots on the magnets, the magnet structure generates a combination of unequal pole arc coefficients in three-dimensional space. By combining different pole arc coefficients, the Fourier decomposition coefficient of the order nz / 2p is reduced, thereby reducing the cogging torque of the motor.

[0016] Therefore, this invention has a theoretical basis and features the ability to reduce the Fourier decomposition coefficients of the nz / 2p order by using different combinations of unequal pole arc coefficients, thereby weakening the magnetic slot torque of the motor as much as possible. Attached Figure Description

[0017] Figure 1 This is a structural schematic diagram of Embodiment 1 of the present invention;

[0018] Figure 2 This is a schematic diagram of the structure of the magnet body and the housing in Embodiment 2;

[0019] Figure 3 This is a schematic diagram of the structure of the magnet body and the housing in Example 3;

[0020] Figure 4 A schematic diagram of a parallel magnetized tile;

[0021] Figure 5 The diagram shows the expression for the magnetic field strength in Example 1;

[0022] Figure 6 The diagram shows the expression for the magnetic field strength in Example 2;

[0023] Figure 7 The diagram shows the expression for the magnetic field strength in Example 3. Detailed Implementation

[0024] The technical solution of the present invention will be further described in detail below through embodiments and in conjunction with the accompanying drawings.

[0025] Example 1:

[0026] like Figure 1 As shown, a magnet for a DC brushed motor includes a magnet body 1 with a tile-shaped structure. The two ends of the magnet body 1 in the arc length direction are axially symmetrical. At least one double-sided groove 11 and at least one single-sided groove 12 are provided on the inner side of the end in the arc length direction of the magnet body 1. The double-sided groove 11 is located in the middle in the height direction of the magnet body 1, and the single-sided groove 12 is provided on one side in the height direction of the magnet body. The single-sided groove 12 and the double-sided groove 11 are distributed at intervals in the height direction of the magnet. The double-sided groove 11 includes two first sidewalls 111 and a first groove. Bottom 112, single-sided slot 12 includes a second sidewall 121 and a second slot bottom 122; a DC brushed motor containing magnets includes a housing 2 and a rotor rotatably supported between the housing 2 and the housing 2. The inner wall of the housing 2 is provided with a plurality of magnets; the inner side of the end of the magnet body 1 in the arc length direction has only one single-sided slot and one double-sided slot. The number of single-sided slots and the number of double-sided slots can be modified according to the optimization effect of the magnetic slot torque. The magnets are set on the inner wall of the housing, and different numbers of magnets can be set according to actual needs. The rotor is set on the inner side of the arc surface of the magnets.

[0027] The width of the double-sided groove 11 along the arc length of the magnet body is between 1 / 6 and 1 / 3 of the length of the inner arc surface of the magnet. The depth of the double-sided groove 11 is set along the thickness direction of the magnet body 1. The maximum depth of the double-sided groove 11 is greater than half the thickness of the magnet body 1. The depth of the double-sided groove 11 gradually increases from the middle of the arc length near the magnet body 1 to both ends of the arc length of the magnet body 1. The first groove bottom 121 is formed by two inclined surfaces 123 that are inclined along the height direction of the magnet body 1. The inclined surfaces 123 are inclined from the root of the first sidewall 111 to the joint of the two inclined surfaces 123 from the inside to the outside of the thickness direction of the magnet body 1. The two inclined surfaces 123 are joined together to form a V-shaped structure. The first groove bottom 112 and the second groove bottom 122 are formed by one or two arc-shaped surfaces. A tooth 13 is formed between the double-sided groove 11 and the single-sided groove 12. In this embodiment, the width of the double-sided groove 11 along the arc length of the magnet body is 1 / 4 of the length of the inner arc surface of the magnet.

[0028] like Figure 4 As shown, at any position α, the distribution of the radial component of the air gap magnetic flux density along the brush surface is expressed by the following formula:

[0029]

[0030] h m h is the length in the magnetization direction at the center of the permanent magnet. m (θ) is the length of the permanent magnet in the magnetization direction at the angle θ with the center line of the magnetic pole, δ is the air gap width, and B r It is the air gap magnetic flux density.

[0031] The capacity of the magnets inside the motor can be expressed by the following formula:

[0032]

[0033] In the formula:

[0034] pass Fourier decomposition can reveal This has a significant impact on cogging torque, and only the Fourier decomposition coefficients of order nz / 2p affect the cogging torque. (n is the order of the decomposition, Z is the number of slots, and p is the number of pole pairs of the magnet)

[0035]

[0036]

[0037] Where Rm1 and Rm2 are the inner and outer radii of the permanent magnet, respectively, and θ is the angle between the permanent magnet and the center line.

[0038] By performing Fourier decomposition on the above function, it can be found that only the Fourier decomposition coefficients of order nz / 2p have an impact on the cogging torque. If the number of poles and slots of the motor are fixed, then the cogging torque will be affected. The Fourier decomposition coefficients have also been determined. By optimizing the appropriate coefficients, the cogging torque can be significantly reduced.

[0039] While the simple pole arc coefficient may be optimal for optimizing cogging torque, it may not be the best solution for overall motor performance. This application addresses this by optimizing the performance of parallel magnetized tile magnets and creating double and single-sided slots on the magnets. This results in a combination of unequal pole arc coefficients in the magnet structure in three-dimensional space. By combining different pole arc coefficients, the Fourier decomposition coefficient of the nz / 2p order is reduced, thereby lowering the cogging torque of the motor.

[0040] Changes in magnetic field strength, such as Figure 5 As shown: The magnetic field is a rectangular wave.

[0041] Example 2:

[0042] like Figure 2 As shown, the double-sided groove 11 has single-sided grooves 12 on both the upper and lower sides of the magnet body 1 in the height direction, and the two single-sided grooves 12 are symmetrically arranged vertically in the height direction of the magnet body. The other structures of this embodiment are the same as those of Embodiment 1, and will not be described again here.

[0043] Changes in magnetic field strength, such as Figure 6 As shown: The magnetic field is a trapezoidal wave.

[0044] Example 3: Figure 3 As shown, the double-sided groove 11 has single-sided grooves 12 on both the upper and lower sides in the height direction of the magnet body 1, and the depths of the two single-sided grooves 12 are different. The other structures of this embodiment are the same as those of Embodiment 1, and will not be described again here.

[0045] Changes in magnetic field strength, such as Figure 7 As shown: The magnetic field is a bell-shaped wave.

Claims

1. A magnet for a DC brushed motor, characterized in that: The magnet body (1) includes a tile-shaped structure. The two ends of the magnet body (1) in the arc length direction are axially symmetrical. The inner side of the end of the magnet body (1) in the arc length direction is provided with at least one double-sided groove (11) and at least one single-sided groove (12). The double-sided groove (11) is located in the middle of the magnet body (1) in the height direction, and the single-sided groove (12) is located on one side of the magnet body in the height direction. The single-sided groove (12) and the double-sided groove (11) are distributed at intervals in the height direction of the magnet. The double-sided groove (11) includes two first sidewalls (111) and a first... The bottom of the groove (112) includes a second sidewall (121) and a second bottom of the groove (122); a tooth (13) is formed between the double sidewall (11) and the single sidewall (12); the first bottom of the groove (121) is formed by two inclined surfaces (123) that are inclined along the height direction of the magnet body (1). The inclined surfaces (123) are inclined from the root of the first sidewall (111) to the joint of the two inclined surfaces (123) from the inside to the outside in the thickness direction of the magnet body (1). The two inclined surfaces (123) are joined together to form a V-shaped structure.

2. The magnet of the DC brushed motor according to claim 1, characterized in that: The width of the double-sided groove (11) along the arc length of the magnet body is between 1 / 6 and 1 / 3 of the length of the inner arc surface of the magnet.

3. The magnet of the DC brushed motor according to claim 1 or 2, characterized in that: The depth of the double-sided groove (11) is set along the thickness direction of the magnet body (1), and the maximum depth of the double-sided groove (11) is greater than half the thickness of the magnet body (1).

4. The magnet of the DC brushed motor according to claim 1, 2, or 3, characterized in that: The depth of the double-sided groove (11) gradually increases from the middle of the arc length near the magnet body (1) towards both ends of the arc length of the magnet body (1).

5. The magnet of the DC brushed motor according to claim 1, 2, or 3, characterized in that: The double-sided groove (11) is provided with single-sided grooves (12) on both the upper and lower sides of the magnet body (1) in the height direction, and the two single-sided grooves (12) are symmetrically arranged in the height direction of the magnet body.

6. The magnet of the DC brushed motor according to claim 1, 2, or 3, characterized in that: The double-sided groove (11) has a single-sided groove (12) on both the upper and lower sides of the magnet body (1) in the height direction, and the two single-sided grooves (12) have different depths.

7. The magnet structure of the DC brushed motor according to claim 1, 2, or 3, characterized in that: The first groove bottom (112) and the second groove bottom (122) are composed of one or two arc-shaped surfaces.

8. A brushed DC motor comprising the magnet described in any one of claims 1-7, characterized in that: It includes a housing (2) and a rotor that is rotatably supported between the housing (2) and the housing (2), wherein the inner wall of the housing (2) is provided with a plurality of the magnets.

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