Magnetic pole T tail asymmetric structure and method for reducing stress

Abstract

The invention discloses a magnetic pole T tail asymmetric structure and a stress reduction method, and belongs to the technical field of generators, the magnetic pole T tail asymmetric structure comprises a magnetic pole, a plurality of T tails are uniformly arranged on the magnetic pole, the plurality of T tails comprise a middle T tail and outer T tails located at two sides, and the outer side surface of a straight rod of each outer T tail is provided with a stress reduction structure which is recessed inwards. And the outer T tail forms an asymmetric structure through the stress reduction structure, so that the technical problem that the stress at the outer chamfer of the outer T tail is too high is effectively solved, the stability of the magnetic pole T tail structure is enhanced, and the reliability and stability of the overall operation of the generator set are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of generators, and particularly relates to an asymmetrical structure of a pole T-tail and a method for reducing stress. Background Art

[0002] The pole is an important component of the rotating part of the motor and is used to generate a magnetic field for electromechanical energy conversion. When the motor is running, the pole rotates with the rotor, so the pole needs to be reliably fixed on the yoke. When using T-tail fixation, as Figure 5 shown, the T-tails of the pole 1 and the yoke 2 both include a boss and a straight rod connecting the boss to the root of the pole body. A T-tail groove corresponding to the pole 1 is formed on the yoke 2. The T-tail of the pole 1 is inserted into the T-tail groove of the yoke 2, and a certain space is reserved radially on both sides of the T-tail of the pole 1 and the T-tail groove of the yoke 2. A pair of pole keys 4 are driven into this space to radially fix the pole 1 on the yoke 2.

[0003] Currently, for poles with a multi-T-tail structure, the sizes of each T-tail are the same, that is, an equal-height and equal-width pole T-tail structure. As Figure 5-6 shown, with the pole center line 5 as the center, the side closer to the pole center line 5 is the inner side, and the side far from the pole center line 5 is the outer side. Each pole T-tail includes a straight rod 3, a boss 6, an inner side surface 11, an outer side surface 12, an inner chamfer, and an outer chamfer. The straight rod 3 is centrally arranged on the boss 6; and the profile lines of the inner side surface 11 and the outer side surface 12 of the straight rod 3 of each pole T-tail are both vertical structures. The inner chamfer of each T-tail is located between the inner side surface 11 and the boss 6, and the outer chamfer of each pole T-tail is located between the outer side surface 12 and the boss 6. Based on this structure, a stress distribution analysis is carried out. Taking the pole center line 5 as the intercepting line and Figure 5 the direction shown as an example, the right half model of the pole 1 is selected as the analysis object, and the analysis result is as Figure 6-7 shown. When the pole is running normally, the stress at the inner chamfer and the outer chamfer of each pole T-tail is relatively high, and the stress distribution shows non-uniformity. Specifically: the stress at the inner chamfer of the middle T-tail 7 is 200.6 MPa, and the stress at the outer chamfer of the middle T-tail 7 is 261.8 MPa; the stress at the inner chamfer of the outer T-tail 8 is 175.3 MPa, and the stress at the outer chamfer of the outer T-tail 8 is as high as 352.6 MPa, which is the location of the maximum stress value. Moreover, there are significant differences in the maximum stresses at the inner and outer chamfers of the middle T-tail 7 and the outer T-tail 8 respectively, and the difference in the outer T-tail 8 is particularly significant. Exploring the reasons, the pole coils are located on both sides of the pole body, resulting in the outer T-tail 8 located at the edge and far from the pole center line 5 bearing more weight. At the same time, due to the arrangement position of the outer T-tail 8 deviating from the centrifugal force direction and bearing bending stress, the stress at the outer chamfer of the outer T-tail 8 is significantly higher than the stress of the middle T-tail 7. This may lead to a series of serious consequences such as pole loosening, damage, increased vibration, increased noise, and decreased efficiency, posing a major threat to the stable operation of the generator set.

[0004] Therefore, in view of the problem of excessive stress at the outer chamfer of the outer T-tail in the current equal-width and equal-height magnetic pole T-tail structure, in order to improve the stability and reliability of this structure, it is extremely necessary to design a magnetic pole T-tail structure with optimized stress distribution and reasonable stiffness. Summary of the Invention

[0005] The purpose of the present invention is to solve the above problems existing in the prior art, and provides a non-symmetric structure of the magnetic pole T-tail and a method for reducing stress. The present invention forms a non-symmetric structure by arranging a stress-reducing structure that is recessed inward on the outer side surface of the straight rod of the outer T-tail, effectively solving the technical problem of excessive stress at the outer chamfer of the outer T-tail, enhancing the stability of the magnetic pole T-tail structure, and further improving the reliability and stability of the overall operation of the generator set.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows: On the one hand, the present invention provides a non-symmetric structure of the magnetic pole T-tail, including a magnetic pole, on which a plurality of T-tails are evenly arranged. The plurality of T-tails include a middle T-tail and outer T-tails on both sides. A stress-reducing structure that is recessed inward is provided on the outer side surface of the straight rod of the outer T-tail, and the outer T-tail forms a non-symmetric structure through the stress-reducing structure to reduce the stress at the outer chamfer.

[0007] When the number of the T-tails is an even number, a stress-reducing structure is also provided on the outer side surface of the straight rod of the middle T-tails located on both sides of the magnetic pole center line.

[0008] When the number of the T-tails is an odd number, a stress-reducing structure is also provided on the outer side surface of the straight rod of the middle T-tails that are symmetrically located on both sides of the magnetic pole center line.

[0009] The stress-reducing structure is an arc-shaped notch, the opening of the arc-shaped notch faces the outer side surface of the straight rod, and both ends of the arc-shaped notch are respectively located at the upper and lower ends of the outer side surface of the straight rod.

[0010] The height of the arc of the arc-shaped notch on the middle T-tail is less than the height of the arc of the arc-shaped notch on the outer T-tail.

[0011] The stress-reducing structure is calculated according to the width of the straight rod and finite element analysis. The calculation formula is: c = a×b, In the formula, c represents the height of the arc of the arc-shaped notch, a represents the coefficient of the height of the arc, the coefficient of the height of the arc is obtained through finite element analysis trial calculation, the range value of a is 0.1 to 0.4, and b represents the width of the straight rod.

[0012] The stress-reducing structure is to reduce the width of the straight rod as a whole from the outer side surface of the straight rod.

[0013] The reduction amount of the width of the straight rod of the middle T-tail that decreases the width of the straight rod as a whole inward on the outer side of the straight rod is less than the reduction amount of the width of the straight rod of the outer T-tail that decreases the width of the straight rod as a whole inward on the outer side of the straight rod.

[0014] The stress reduction structure is calculated based on the width of the straight rod and finite element analysis, and the calculation formula is: d n = k×b×n, In the formula, n represents the T-tail number from the magnetic pole center line to both sides, n is a non-zero natural number sequence, the T-tail number closest to the magnetic pole center line is 1, and the T-tail numbers on each side increase in sequence; k represents the reduction coefficient of the width of the straight rod, and the reduction coefficient is obtained through finite element analysis trial calculation, and the range value of k is from 0.01 to 0.1; d n represents the reduction amount of the width of the straight rod of the nth T-tail that decreases the width of the straight rod as a whole inward on the outer side of the straight rod; b represents the width of the straight rod before the width of the straight rod of the T-tail decreases as a whole inward on the outer side of the straight rod.

[0015] On the other hand, the present invention also provides a method for reducing stress of the magnetic pole T-tail asymmetric structure. This method forms an asymmetric structure to reduce the outer chamfer stress by setting an arc-shaped notch on the outer side of the straight rod of the outer T-tail, and the arc-shaped notch is calculated based on the width of the straight rod and finite element analysis.

[0016] The present invention also provides another method for reducing stress of the magnetic pole T-tail asymmetric structure. This method forms an asymmetric structure to reduce the outer chamfer stress by reducing the width of the straight rod as a whole inward on the outer side of the straight rod; the reduction amount of the width of the straight rod of the outer side of the straight rod of each T-tail that decreases the width of the straight rod as a whole inward is calculated based on the width of the straight rod and finite element analysis.

[0017] The advantages of adopting the present invention are as follows: 1. For the magnetic pole T-tail asymmetric structure provided by the present invention, first, a stress reduction structure that is recessed inward is provided on the outer side of the straight rod of the outer T-tail, thereby forming an asymmetric structure. This design effectively reduces the stiffness of the outer side of the straight rod of the outer T-tail. Compared with the existing magnetic pole T-tail structure with equal width and height, the asymmetric structure significantly reduces the stress on the outer side of the straight rod of the outer T-tail, especially at the outer chamfer, thus effectively solving the technical problem of excessive stress at the outer chamfer of the outer T-tail and enhancing the durability of the magnetic pole T-tail.

[0018] Secondly, the design of this asymmetric structure also reduces the stress difference between the inner chamfer and the outer chamfer of the magnetic pole T-tail, improves the uniformity of stress distribution, and further enhances the stability of the magnetic pole T-tail structure. This improvement ultimately improves the overall operation reliability and stability of the generator set.

[0019] 2. The asymmetric structure of the magnetic pole T-tail provided by the present invention improves the stress distribution uniformity and structural stability of the entire magnetic pole T-tail structure by providing a stress reduction structure on the outer side surface of the straight rods of all intermediate T-tails.

[0020] 3. The asymmetric structure of the magnetic pole T-tail provided by the present invention designs an arc-shaped notch as the stress reduction structure, optimizes its rise, and obtains the specific stress numerical distribution results according to the straight rod width and finite element analysis. In particular, when the rise coefficient of the arc-shaped notch is 0.32, the stress value of the outer chamfer of the outer T-tail decreases from 352.6 MPa to 277.2 MPa. It can be seen that by introducing the arc-shaped notch design to reduce the stiffness of the outer side of the outer T-tail, the stress distribution of the magnetic pole T-tail structure has been significantly improved. This arc-shaped notch design effectively reduces the maximum stress value of the outer chamfer of the outer T-tail in the T-tail structure and makes the stress difference between the outer chamfer and the inner chamfer of the outer T-tail tend to decrease, thereby enhancing the stress uniformity of the outer T-tail and even the entire magnetic pole T-tail structure.

[0021] 4. The asymmetric structure of the magnetic pole T-tail provided by the present invention forms a stress reduction structure by reducing the width of the straight rod from the outer side surface of the straight rod as a whole, constructs an asymmetric structure of the inner and outer side surfaces of the straight rod of the T-tail, and optimizes the reduction amount according to the position of the T-tail and finite element analysis to obtain the specific stress numerical distribution results. In particular, when the reduction amount coefficient of the straight rod width is 0.04, the stress value of the outer chamfer of the outer T-tail decreases from 352.6 MPa to 259.5 MPa. It can be seen that the design of reducing the width of the straight rod as a whole not only greatly reduces the stress difference between the inner chamfer and the outer chamfer of the intermediate T-tail and between the inner chamfer and the outer chamfer of the outer T-tail, realizing a more uniform stress distribution, but also the maximum stress at the outer chamfer of the outer T-tail is reduced by 26% compared with the equal-width straight rod magnetic pole T-tail structure in the prior art, realizing the effective dispersion and reduction of the stress of the asymmetric structure of the magnetic pole T-tail, and further enhancing the stability and durability of the structure.

[0022] 5. A method for reducing stress of the asymmetric structure of the magnetic pole T-tail provided by the present invention effectively reduces the stress of the outer chamfer of the outer T-tail through the design of the arc-shaped notch, realizes the optimization of the stress distribution, and improves the stability and reliability of the overall structure.

[0023] 6. Another method for reducing stress of the asymmetric structure of the magnetic pole T-tail provided by the present invention forms an asymmetric structure of the inner and outer side surfaces of the straight rod by reducing the width of the outer side surface of the straight rod as a whole. This method accurately adjusts the reduction amount of the straight rod width based on finite element analysis to ensure that while maintaining a reasonable stiffness of the magnetic pole T-tail structure, it reduces the stress difference between the inner chamfer and the outer chamfer of the magnetic pole T-tail and enhances the stress distribution uniformity of the structure, thereby enhancing the reliability and durability of the structure. Description of the Drawings

[0024] Figure 1 Schematic diagram of the stress-reducing structure with an arc-shaped notch in the present invention; Figure 2 Equivalent stress nephogram of the stress-reducing structure with an arc-shaped notch in the present invention; Figure 3 Schematic diagram of the stress-reducing structure with the width of the straight rod decreasing inward in the present invention; Figure 4 Equivalent stress nephogram of the stress-reducing structure with the width of the straight rod decreasing inward in the present invention; Figure 5 Schematic diagram of the assembly of the pole and yoke with equal-width straight rods in the prior art; Figure 6 Schematic diagram of the T-tail of the pole with equal-width straight rods in the prior art; Figure 7 Equivalent stress nephogram of the T-tail of the pole with equal-width straight rods in the prior art.

[0025] The labels in the figure are: 1, pole; 2, yoke; 3, straight rod; 4, pole key; 5, pole center line; 6, boss; 7, middle T-tail; 8, outer T-tail; 9, arc-shaped notch; 11, inner side; 12, outer side. Detailed implementation manners

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. For the convenience of description, the relative positional relationships of the components are all described according to the layout of the drawings in the specification. For example, the positional relationships such as front, rear, upper, lower, left, and right are determined according to the layout direction of the drawings in the specification.

[0027] Embodiment 1 This embodiment is the basic embodiment of the present invention, and it provides a non-symmetrical structure of the pole T-tail, as shown in Figure 1 、 Figure 3 and understood in combination with Figure 5 , including a pole 1, on which a plurality of T-tails are uniformly arranged. The plurality of T-tails include a middle T-tail 7 and outer T-tails 8 on both sides.

[0028] The total number of T-tails of the magnetic pole with a multi-T-tail structure is usually set to three or more. Specifically, when the total number of T-tails is three, they are the first T-tail, the second T-tail, and the third T-tail respectively. Among them, the first T-tail and the third T-tail are used as outer T-tails, and the second T-tail is centrally arranged along the magnetic pole center line 5; if the total number increases to four, they are the first T-tail, the second T-tail, the third T-tail, and the fourth T-tail respectively. The first T-tail and the fourth T-tail are the outer T-tails, and the second T-tail and the third T-tail are the middle T-tails and are respectively located on both sides of the magnetic pole center line 5; if the total number is five, it includes the first T-tail, the second T-tail, the third T-tail, the fourth T-tail, and the fifth T-tail. The first T-tail and the fifth T-tail are the outer T-tails, the second T-tail and the fourth T-tail are the middle T-tails, and the third T-tail is centrally arranged along the magnetic pole center line 5. And so on, the number of T-tails can be increased according to actual needs.

[0029] Furthermore, a stress-reducing structure that is recessed inward is provided on the outer side surface 12 of the straight rod 3 of the outer T-tail 8. The outer T-tail 8 forms an asymmetric structure through the stress-reducing structure to reduce the outer chamfer stress of the outer T-tail 8.

[0030] Embodiment 2 As a preferred embodiment of the present invention, on the basis of the structure of Embodiment 1, the layout of the stress-reducing structure is optimized.

[0031] When the number of T-tails is an even number, a stress-reducing structure is also provided on the outer side surface 12 of the straight rod 3 of the middle T-tails 7 located on both sides of the magnetic pole center line 5.

[0032] When the number of T-tails is an odd number, a stress-reducing structure is also provided on the outer side surface 12 of the straight rod 3 of the relatively symmetric middle T-tails 7 located on both sides of the magnetic pole center line 5. Specifically, when the number of T-tails is three, there is no middle T-tail, and the stress-reducing structure is only provided on the outer T-tail; when the number of T-tails is five, they are the first T-tail, the second T-tail, the third T-tail, the fourth T-tail, and the fifth T-tail respectively. The third T-tail is centrally arranged along the magnetic pole center line 5. At this time, the second T-tail and the fourth T-tail are used as the relatively symmetric middle T-tails, and the stress-reducing structure is also provided on the second T-tail and the fourth T-tail.

[0033] Embodiment 3 As another preferred embodiment of the present invention, in this embodiment, the stress-reducing structure is further optimized on the basis of Embodiment 1.

[0034] Specifically, as Figure 1 shown, the stress-reducing structure is an arc-shaped notch 9. The opening of the arc-shaped notch 9 faces the outer side surface 12 of the straight rod 3, and both ends of the arc-shaped notch 9 are respectively located at the upper and lower ends of the outer side surface 12 of the straight rod 3.

[0035] Furthermore, the height c of the arc of the arc-shaped notch 9 on the middle T-tail 7 is less than the height c of the arc of the arc-shaped notch 9 on the outer T-tail 8.

[0036] The stress reduction structure is calculated based on the width of the straight rod 3 and finite element analysis. The calculation formula is as follows: c = a × b, where c represents the sagitta of the arc-shaped notch, a represents the sagitta coefficient, which is obtained through finite element analysis trial calculation, the range value of a is 0.1 to 0.4, and b represents the width of the straight rod.

[0037] The following will be described with reference to Figure 1 and Figure 2 In the display of Figure 1 , the arc-shaped notch 9 is not provided in the middle T-tail 7 on the left side, and it remains consistent with the structure of the equal-width straight rod in Figure 6 . Only the arc-shaped notch 9 is provided on the outer T-tail 8 on the right side to reduce the stiffness of the outer side of the straight rod 3 of the outer T-tail 8. Based on this structural model, the range value of the sagitta coefficient a is selected, that is, between 0.1 and 0.4, and multiple trial calculations are carried out through the finite element analysis method. When the value of the sagitta coefficient a is set to 0.32, the following better stress distribution results are obtained as shown in Figure 2 : The maximum stress is concentrated at the chamfer formed by the straight rod 3 and the boss 6. Taking the direction shown in Figure 1 as an example, among them, the stress at the inner chamfer of the straight rod 3 of the middle T-tail 7 on the left side is 197 MPa, and the stress at the outer chamfer is 280.8 MPa; the stress at the inner chamfer of the straight rod 3 of the outer T-tail 8 on the right side is 193.1 MPa, and the stress at the outer chamfer is reduced to 277.2 MPa compared with the equal-width straight rod magnetic pole T-tail structure shown in Figure 5 , Figure 6 .

[0038] It can be seen that by introducing the arc-shaped notch 9 design to reduce the stiffness of the outer side of the outer T-tail 8, the stress distribution of the magnetic pole T-tail structure has been significantly improved. Specifically, this design effectively reduces the maximum stress value at the outer chamfer of the outer T-tail in the T-tail structure, and makes the stress difference between the outer chamfer and the inner chamfer of the outer T-tail 8 tend to decrease, thereby enhancing the stress uniformity of the outer T-tail 8 and even the entire magnetic pole T-tail structure.

[0039] In addition, when the number of middle T-tails 7 on each side of the two sides of the magnetic pole center line 5 is two or more, the sagitta of the arc-shaped notch 9 of each middle T-tail 7 increases sequentially from the magnetic pole center line 5 to both sides.

[0040] In some embodiments, the arc-shaped notch 9 can also be replaced by other types of stress reduction structure designs such as V-shaped notches and U-shaped notches. The inward depression depth of these notches can also be determined according to the width of the straight rod 3 and combined with finite element analysis calculation.

[0041] Embodiment 4 As the best embodiment of the present invention, on the basis of Embodiment 2, this embodiment further optimizes the stress reduction structure in another form, specifically as follows: The stress reduction structure is to integrally reduce the width of the straight rod 3 inward from the outer side surface 12 of the straight rod 3. As Figure 3 shown, the reduction amount d1 of the width of the straight rod 3 integrally reduced inward from the outer side surface 12 of the straight rod 3 of the middle T-tail 7 is less than the reduction amount d2 of the width of the straight rod 3 integrally reduced inward from the outer side surface 12 of the straight rod 3 of the outer T-tail 8.

[0042] Furthermore, when the number of middle T-tails 7 on each side of the two sides of the magnetic pole center line 5 is two or more, the reduction amount of the width integrally reduced inward from the outer side surface 12 of the straight rod 3 of each T-tail increases sequentially from the magnetic pole center line 5 to both sides.

[0043] The stress reduction structure is obtained according to the width of the straight rod 3 and finite element analysis calculation. The calculation formula is: d n = k×b×n, wherein, n represents the T-tail number from the magnetic pole center line to both sides. n is a non-zero natural number sequence. The T-tail number closest to the magnetic pole center line is 1, and the T-tail numbers on each side increase sequentially; k represents the reduction amount coefficient of the straight rod width. The reduction amount coefficient is obtained through finite element analysis trial calculation. The range value of k is 0.01 to 0.1; d n represents the reduction amount of the width of the straight rod integrally reduced inward from the outer side surface of the straight rod of the nth T-tail; b represents the width of the straight rod before the outer side surface of the straight rod of the T-tail is integrally reduced inward.

[0044] The following is described with reference to Figure 3 and Figure 4 . Taking the direction shown in Figure 3 as an example, the outer side surface 12 of the straight rod 3 of the middle T-tail 7 on the left side is obtained by integrally moving a distance d1 to the left starting from its corresponding dotted line L position; the outer side surface 12 of the straight rod 3 of the outer T-tail 8 on the right side is obtained by integrally moving a distance d2 to the left starting from its corresponding dotted line N position. The straight-line distance between the inner side surface 11 of the straight rod 3 of the middle T-tail 7 on the left side and the dotted line L, and the straight-line distance between the inner side surface 11 of the straight rod 3 of the outer T-tail 7 on the right side and the dotted line N are exactly the width b of the straight rod before the outer side surface 12 of the straight rod 3 of the T-tail is integrally reduced inward. On the basis of this structural model, according to the above calculation formula, the range value of the reduction amount coefficient k is selected, that is, between 0.01 and 0.1, and multiple trial calculations are carried out through the finite element analysis method. When the value of the reduction amount coefficient k is set to 0.04, d1 = 0.04b, d2 = 0.08b, and the better stress distribution result shown in Figure 4 is obtained: the maximum stress is concentrated at the chamfer formed by the straight rod 3 and the boss 6.Figure 3 Taking the direction shown as an example, among which, the stress at the inner chamfer of the straight rod 3 of the middle T-tail 7 on the left side is 199.4 MPa, and the stress at the outer chamfer is 203.2 MPa; the stress at the inner chamfer of the straight rod 3 of the outer T-tail 8 on the right side is 167.3 MPa, and the stress at the outer chamfer is reduced to 259.5 MPa compared with Figure 5 、 Figure 6 the equal-width straight rod magnetic pole T-tail structure of

[0045] Thus, by reducing the width of the straight rod 3 as a whole from the outer side surface 12 of the straight rod 3 to form a stress-reducing structure, an asymmetric structure of the inner side surface 11 and the outer side surface 12 of the straight rod 3 of the T-tail is constructed. This design adjustment not only greatly reduces the stress difference between the inner chamfer and the outer chamfer of the middle T-tail 7, and between the inner chamfer and the outer chamfer of the outer T-tail 8, realizing a more uniform stress distribution, but also, the maximum stress at the outer chamfer of the outer T-tail 8 is compared with Figure 5 、 Figure 6 the equal-width straight rod magnetic pole T-tail structure shown in

[0046] Example 5 For Example 3, the present invention provides a method for reducing stress of an asymmetric structure of a magnetic pole T-tail. This method sets an arc-shaped notch 9 on the outer side surface 12 of the straight rod 3 of the outer T-tail 8 to make the outer T-tail 8 form an asymmetric structure so as to reduce the stress at the outer chamfer.

[0047] The arc-shaped notch 9 is obtained according to the width of the straight rod 3 and finite element analysis calculation. The calculation formula is: c = a×b, wherein, c represents the rise of the arc-shaped notch, a represents the rise coefficient, the rise coefficient is obtained through finite element analysis trial calculation, the range value of a is from 0.1 to 0.4, and b represents the width of the straight rod.

[0048] As Figure 1 shown, keeping the structure of the middle T-tail 7 unchanged from the Figure 6 equal-width straight rod structure in Figure 2 and only opening an arc-shaped notch 9 on the outer side surface of the straight rod 3 of the outer T-tail 8. According to the calculation formula, when the value of a is set to 0.32, that is, the rise c of the arc-shaped notch 9 is equal to 0.32 times the width b of the straight rod, the stress distribution result shown in Figure 1Taking the direction shown as an example, among them, the stress at the inner chamfer of the straight rod 3 of the middle T-tail 7 on the left is 197 MPa, and the stress at the outer chamfer is 280.8 MPa; the stress at the inner chamfer of the straight rod 3 of the outer T-tail 8 on the right is 193.1 MPa, and the stress at the outer chamfer is reduced to 277.2 MPa compared with the equal-width straight rod magnetic pole T-tail structure shown in Figure 5 , Figure 6 .

[0049] Example 6 For Example 4, the present invention provides another method for reducing stress in the asymmetric structure of the magnetic pole T-tail. This method reduces the stress at the outer chamfer by integrally reducing the width of the straight rod 3 inward on the outer side surface 12 of the straight rod 3 to form an asymmetric structure for the outer T-tail 8.

[0050] The reduction amount of the width of the straight rod 3 integrally reduced inward on the outer side surface 12 of the straight rod 3 of each T-tail is calculated according to the width of the straight rod 3 and finite element analysis. The calculation formula is: d n = k×b×n, In the formula, n represents the T-tail number from the magnetic pole center line to both sides. n is a non-zero natural number sequence. The T-tail number closest to the magnetic pole center line is 1, and the T-tail numbers on each side increase in sequence; k represents the reduction amount coefficient of the straight rod width, and the reduction amount coefficient is obtained through finite element analysis trial calculation. The range value of k is 0.01 to 0.1; d n represents the reduction amount of the width of the straight rod integrally reduced inward on the outer side surface of the straight rod of the nth T-tail; b represents the width of the straight rod before the outer side surface of the T-tail straight rod is integrally reduced inward.

[0051] As Figure 3 shown, the outer side surface 12 of the straight rod 3 of the middle T-tail 7 on the left is obtained by moving the whole left by a distance d1 starting from its corresponding dotted line L position; the outer side surface 12 of the straight rod 3 of the outer T-tail 8 on the right is obtained by moving the whole left by a distance d2 starting from its corresponding dotted line N position. The straight-line distance between the inner side surface 11 of the straight rod 3 of the middle T-tail 7 on the left and the dotted line L, and the straight-line distance between the inner side surface 11 of the straight rod 3 of the outer T-tail 7 on the right and the dotted line N are exactly the width b of the straight rod before the outer side surface 12 of the T-tail straight rod is integrally reduced inward. Based on this structural model, according to the above calculation formula, the range value of the reduction amount coefficient k is selected, that is, between 0.01 and 0.1, and multiple trial calculations are carried out through the finite element analysis method. When the value of the reduction amount coefficient k is set to 0.04, d1 = 0.04b, d2 = 0.08b, and the better stress distribution result shown in Figure 4 is obtained: the maximum stress is concentrated at the chamfer formed by the straight rod 3 and the boss 6. Figure 3Taking the direction shown as an example, among which, the stress at the inner chamfer of the straight rod 3 of the middle T-tail 7 on the left side is 199.4 MPa, and the stress at the outer chamfer is 203.2 MPa; the stress at the inner chamfer of the straight rod 3 of the outer T-tail 8 on the right side is 167.3 MPa, and the stress at the outer chamfer is reduced to 259.5 MPa compared with the equal-width straight rod magnetic pole T-tail structure of Figure 5 and Figure 6 .

[0052] As described above, the above are only specific embodiments of the present invention. Any feature disclosed in this specification, unless specifically described, can be replaced by other equivalent or similar-purpose alternative features; all the features disclosed, or all the steps in any method or process, except for mutually exclusive features and / or steps, can be combined in any way.

Claims

1. A magnetic pole T-tail asymmetric structure, comprising a magnetic pole (1), on which a plurality of T-tails are uniformly arranged. The plurality of T-tails include a middle T-tail (7) and outer T-tails (8) located on both sides, and is characterized in that: The outer side surface (12) of the straight rod (3) of the outer T-tail (8) is provided with a stress-reducing structure that is recessed inward. The outer T-tail (8) forms an asymmetric structure through the stress-reducing structure to reduce the outer chamfer stress.

2. The asymmetric structure of the magnetic pole T-tail according to claim 1, characterized in that: When the number of the T-tails is an even number, the outer side surface (12) of the straight rod (3) of the middle T-tail (7) located on both sides of the magnetic pole center line (5) is also provided with a stress-reducing structure.

3. An asymmetrical structure of magnetic pole T-tail according to claim 1, characterized in that: When the number of the T-tails is an odd number, the outer side surface (12) of the straight rod (3) of the middle T-tail (7) that is symmetrically located on both sides of the magnetic pole center line (5) is also provided with a stress-reducing structure.

4. A magnetic pole T-tail asymmetric structure according to any one of claims 2 or 3, characterized in that: The stress-reducing structure is an arc-shaped notch (9). The opening of the arc-shaped notch (9) faces the outer side surface (12) of the straight rod (3), and both ends of the arc-shaped notch (9) are respectively located at the upper and lower ends of the outer side surface (12) of the straight rod (3).

5. An asymmetrical structure of a magnetic pole T-tail according to claim 4, characterized in that: The height of the arc-shaped notch (9) on the middle T-tail (7) is less than the height of the arc-shaped notch (9) on the outer T-tail (8).

6. An asymmetrical structure of magnetic pole T-tail according to claim 5, characterized in that: The stress-reducing structure is calculated according to the width of the straight rod (3) and finite element analysis. The calculation formula is: c = a×b, In the formula, c represents the height of the arc-shaped notch, a represents the height coefficient, and the height coefficient is obtained through finite element analysis trial calculation. The range value of a is 0.1 to 0.4, and b represents the width of the straight rod.

7. A magnetic pole T-tail asymmetric structure according to any one of claims 2 or 3, characterized in that: The stress-reducing structure is to integrally reduce the width of the straight rod (3) inward from the outer side surface (12) of the straight rod (3).

8. An asymmetric structure of a magnetic pole T-tail according to claim 7, characterized in that: The reduction amount of the width of the straight rod (3) integrally reduced inward from the outer side surface (12) of the straight rod (3) of the middle T-tail (7) is less than the reduction amount of the width of the straight rod (3) integrally reduced inward from the outer side surface (12) of the straight rod (3) of the outer T-tail (8).

9. The asymmetric structure of the magnetic pole T-tail according to claim 8, characterized in that: The stress-reducing structure is calculated according to the width of the straight rod (3) and finite element analysis. The calculation formula is: d n = k × b × n, In the formula, n represents the T-tail numbering from the magnetic pole center line to both sides. n is a non-zero natural number sequence. The T-tail numbering closest to the magnetic pole center line is 1, and the T-tail numbering on each side increases sequentially; k represents the reduction coefficient of the straight bar width, and the reduction coefficient is obtained through finite element analysis and trial calculation. The range value of k is from 0.01 to 0.1; d n represents the reduction amount of the width of the straight bar on the outer side of the straight bar of the nth T-tail decreasing inward as a whole; b represents the width of the straight bar before the outer side of the straight bar of the T-tail decreases inward as a whole.

10. A method for reducing stress by using an asymmetric structure of magnetic pole T-tail, characterized in that: This method forms an asymmetric structure of the outer T-tail (8) to reduce the outer chamfer stress by setting an arc-shaped notch (9) on the outer side surface (12) of the straight rod (3) of the outer T-tail (8). The arc-shaped notch (9) is calculated according to the width of the straight rod (3) and finite element analysis.

11. A method for reducing stress in a non-symmetrical structure of a magnetic pole T-tail, characterized in that: This method forms an asymmetric structure of the outer T-tail (8) to reduce the outer chamfer stress by integrally reducing the width of the straight rod (3) inward from the outer side surface (12) of the straight rod (3); the reduction amount of the width of the straight rod (3) integrally reduced inward from the outer side surface (12) of the straight rod (3) of each T-tail is calculated according to the width of the straight rod (3) and finite element analysis.

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