Motor noise reduction design method and noise reduction motor end cover

Abstract

This invention provides a motor noise reduction design method, relating to the field of noise reduction technology. The method involves dividing the axial length L of the inner cavity of the motor end cover into N segments; obtaining the acoustic modal frequency of the motor end cavity when the sound-absorbing plate is located at its axial position; calculating a second difference between the acoustic modal frequencies of the sound-absorbing plate at each different axial position and the motor vibration excitation frequency under a certain operating condition; if all the second differences at a certain position are greater than a second threshold, that position is a candidate position; calculating the average difference between the acoustic modal frequencies and the motor vibration excitation frequency at each candidate position; and selecting the candidate position with the largest average difference as the optimal noise reduction position for the corresponding operating condition. An optimal noise reduction position can be selected for each operating condition, effectively improving the motor's noise reduction effect. The noise-reducing motor end cover provided by this invention adjusts the sound-absorbing plate to the optimal noise reduction position corresponding to each operating condition, achieving an effective noise reduction effect.

Description

Technical Field

[0001] This invention relates to the field of noise reduction technology, and more particularly to a method for designing motor noise reduction. Furthermore, this invention also relates to a noise-reducing motor end cover. Background Technology

[0002] In the field of rail transit, rail vehicles are mainly driven by electric motors. As train speeds have increased significantly, while providing convenience to people, they have also brought more serious noise problems. Excessive noise not only affects passenger comfort but also causes serious hearing damage to staff, impacting their health. Therefore, the level of train operating noise has become an important indicator for evaluating vehicle performance.

[0003] Motor noise contributes significantly to train operating noise, making its reduction crucial for overall train noise reduction. Mechanical noise, a key component of motor noise, is generated by friction and impact from the motor's moving parts, and amplified through structural and cavity coupling resonance. Currently, the main measure to reduce motor operating noise is to lay sound-absorbing and vibration-damping materials outside the motor; however, this method is ineffective due to limited external space.

[0004] For those skilled in the art, improving the noise reduction effect of motors is a technical problem that needs to be solved. Summary of the Invention

[0005] This invention provides a motor noise reduction design method that can set the optimal noise reduction position for different operating conditions. The optimal noise reduction position of the sound-absorbing plate can effectively reduce the noise generated under the operating conditions. The specific solution is as follows:

[0006] A method for motor noise reduction design includes:

[0007] S3. Divide the axial length L of the inner cavity of the motor end cover into N segments, where N is greater than the number of motor operating conditions; obtain the acoustic modal frequency of the motor end cavity when the sound-absorbing plate is located at the axial position aL / N of the motor end cavity, where a = 1, 2, 3...N. a represents the axial position number, and b represents the corresponding modal order number;

[0008] S4. Under a certain operating condition, when the sound-absorbing plate is located at each different axial position aL / N, where a = 1, 2, 3...N, the frequencies of each of the aforementioned acoustic modes are... With motor vibration excitation frequency Calculate the second difference. If all the second differences when the sound-absorbing panel is located at a certain position are greater than the second threshold, then that axial position is the candidate position.

[0009] S5. Calculate the frequency of each acoustic mode at each of the candidate locations. With the vibration excitation frequency of the motor The average difference between the two values ​​is used to determine the optimal noise reduction position for the corresponding working condition.

[0010] Optionally, it also includes:

[0011] S1. Obtain the motor vibration excitation frequency under various operating conditions of the motor body. i represents the operating condition number, and j represents the vibration excitation frequency number;

[0012] S2. Design the motor end cover structure based on the motor body dimensions, and obtain the motor end cover modal frequency B. k k is the corresponding modal order number; determine the modal frequency B of the motor end cover. k With the vibration excitation frequency of the motor If the first difference between them is less than the first threshold, then the motor end cover structure is redesigned.

[0013] If not, proceed to step S3.

[0014] Optionally, the first threshold is 6Hz; the second threshold is 3Hz.

[0015] The present invention also provides a noise-reducing motor end cap, comprising:

[0016] Motor end cover, fixedly installed on the motor body;

[0017] The sound-absorbing component includes a sound-absorbing panel, which is slidably mounted on the motor end cover. The sound-absorbing panel can slide and adjust its position along the axial direction to change the volume of the cavity at the motor end. The sound-absorbing panel can be adjusted to the corresponding optimal noise reduction position according to the working conditions.

[0018] Optionally, the sound-absorbing assembly includes an adjusting rod, which is vertically fixed to the sound-absorbing plate and slidably mounted on the motor end cover along the axial direction.

[0019] Optionally, the adjusting rod is fixedly installed at the center of the sound-absorbing plate, and the adjusting rod extends through to the outside of the motor end cover.

[0020] Optionally, the sound-absorbing panel is a flat plate with several through holes on its surface, and the surface of the sound-absorbing panel is covered with sound-absorbing material.

[0021] Optionally, the outer wall of the adjusting rod is provided with a threaded section, and the controller controls the motor to drive the nut to rotate in order to move the adjusting rod;

[0022] The controller sets the optimal noise reduction position of the sound-absorbing panel for each operating condition of the motor.

[0023] This invention provides a method for designing motor noise reduction. During the design process, the axial length L of the inner cavity of the motor end cover is divided into N segments; the acoustic modal frequency of the motor end cavity is obtained when the sound-absorbing plate is located at the axial position aL / N of the motor end cavity, where a = 1, 2, 3…N. Each axial position corresponds to multiple acoustic modal frequencies. Under a certain operating condition, the acoustic modal frequencies of the sound-absorbing plate at each different axial position are as follows: With motor vibration excitation frequency Calculate the second difference. If any of the second differences when the sound-absorbing panel is at a certain position is less than the second threshold, then that axial position is excluded. If all the second differences when the sound-absorbing panel is at a certain position are greater than the second threshold, then that position is a candidate position. Calculate the acoustic modal frequencies for each candidate position. With motor vibration excitation frequency The average difference between the two values ​​is used to determine the optimal noise reduction position for the corresponding operating condition. An optimal noise reduction position can be selected for each operating condition; this optimal position is the least likely to produce resonance. Adjusting the sound-absorbing panel to the corresponding optimal noise reduction position under a given operating condition can significantly improve the noise reduction effect of the motor. The noise-reducing motor end cover provided by this invention adjusts the sound-absorbing panel to the optimal noise reduction position corresponding to each operating condition, achieving an effective noise reduction effect. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the isometric structure of the noise-reducing motor end cover of the present invention;

[0026] Figure 2 This is a front view schematic diagram of the noise-reducing motor end cover of the present invention;

[0027] Figure 3 This is an isometric schematic diagram of the sound-absorbing component;

[0028] Figure 4 This is a front view schematic diagram of the sound-absorbing component;

[0029] Figure 5 This is a side view of the sound-absorbing component;

[0030] Figure 6 This is a schematic diagram of a motor using the noise-reducing motor end cover of the present invention;

[0031] Figure 7 This is an isometric structural schematic diagram of another embodiment of the noise-reducing motor end cover of the present invention;

[0032] Figure 8 This is a front view schematic diagram of another embodiment of the noise-reducing motor end cover of the present invention;

[0033] Figure 9 This is an isometric view of the inner side of the motor end cover.

[0034] Figure 10 This is an isometric view of the motor and transmission gear disc;

[0035] Figure 11 This is a front view of the motor and the transmission gear plate;

[0036] Figure 12 This is a schematic diagram of the transmission and engagement between the motor and the sound-absorbing components.

[0037] The image includes:

[0038] 1. Motor end cover; 2. Motor body; 3. Sound-absorbing component; 31. Sound-absorbing plate; 32. Adjusting rod; 4. Controller; 5. Motor; 51. Nut; 52. Transmission gear plate. Detailed Implementation

[0039] The core of this invention lies in providing a motor noise reduction design method that can set the optimal noise reduction position for different operating conditions. The optimal noise reduction position of the sound-absorbing plate can effectively reduce the noise generated under the operating conditions.

[0040] To enable those skilled in the art to better understand the technical solution of the present invention, the following will provide a detailed description of the motor noise reduction design method and the noise reduction motor end cover of the present invention, in conjunction with the accompanying drawings and specific embodiments.

[0041] This invention provides a method for designing motor noise reduction, comprising the following steps:

[0042] S3. Divide the axial length L of the inner cavity of the motor end cover into N segments, where N is greater than the number of motor operating conditions; obtain the acoustic modal frequency of the motor end cavity when the sound-absorbing plate is located at the axial position aL / N of the motor end cavity, where a = 1, 2, 3...N. 'a' represents the axial position number, and 'b' represents the corresponding modal order number. At a certain position on the sound-absorbing plate 31, each mode corresponds to a specific acoustic modal frequency.

[0043] Combination Figure 2 In step S3, the axial length L of the entire inner cavity of the motor end cover 1 is divided into N segments, and the length of each segment is L / N. Figure 2The left end of the motor end cover 1 is used to connect the motor body 2. The sound-absorbing plate 31 can be adjusted horizontally along the axis to the left and right. When the sound-absorbing plate 31 is at the leftmost position, the sound-absorbing plate 31 is located at the axial position 0 of the motor end cavity, and the volume of the motor end cavity is the smallest. When the sound-absorbing plate 31 is at the rightmost position, the sound-absorbing plate 31 is located at the axial position L of the motor end cavity, and the volume of the motor end cavity is the largest. There are N-1 axial position points between the two extreme positions.

[0044] S4. Under a certain operating condition, when the sound-absorbing plate is located at each different axial position aL / N, where a = 1, 2, 3...N, the frequencies of each acoustic mode are... With motor vibration excitation frequency Calculate the second difference. If all the second differences when the sound-absorbing panel is located at a certain position are greater than the second threshold, then that axial position is the candidate position.

[0045] The motor has several operating conditions, such as idling, acceleration, and full speed. Each operating condition has a different speed state. Several corresponding operating conditions can be set according to different speed states. This invention makes corresponding designs for each operating condition to minimize the noise of each operating condition.

[0046] Each working condition is analyzed separately, and the analysis process for each working condition is consistent. This invention describes the process for one working condition. In step S3 above, the axial length of the inner cavity of the motor end cover 1 is divided. Under each working condition, the sound-absorbing plate 31 can be in several different positions along the axial direction. This invention analyzes the state of several different axial positions of the sound-absorbing plate 31 under a certain working condition to obtain the optimal position corresponding to that working condition. The noise reduction effect is best when the sound-absorbing plate 31 is in this position under that working condition.

[0047] Under a certain operating condition, when the sound-absorbing plate 31 is located at each different axial position, each axial position corresponds to a sound mode frequency. Various acoustic modal frequencies With motor vibration excitation frequency The difference between them is the second difference. It should be noted that the smaller the second difference, the higher the acoustic modal frequency. With motor vibration excitation frequency The closer they are, the easier it is for the sound-absorbing plate 31 to resonate when it is in this position; the larger the second difference, the higher the acoustic mode frequency. With motor vibration excitation frequency The greater the difference, the less likely resonance will occur. (Acoustic modal frequencies) It is mainly related to the size of the cavity.

[0048] In step S4, each axial position of the sound-absorbing plate 31 corresponds to several acoustic modal frequencies. Once one of the acoustic mode frequencies With motor vibration excitation frequency The frequencies of the various acoustic modes are relatively close, that is, the frequencies of the sound-absorbing plate 31 when it is located at a certain position. If any one of the second differences is less than the second threshold, the position is excluded; if all the second differences when the sound-absorbing plate is in a certain position are greater than the second threshold, then that axial position is a candidate position; for a specific working condition, there may be several different candidate positions, that is, when the sound-absorbing plate 31 is in each candidate position, the acoustic modal frequency corresponding to each mode is... With motor vibration excitation frequency If the second difference between the two is greater than the second threshold, the subsequent step S5 further selects from several candidate positions and selects the best position as the best noise reduction position.

[0049] S5. Calculate the frequency of each acoustic mode at each candidate location. With motor vibration excitation frequency The average difference between the two values ​​is used to determine the optimal noise reduction location for the corresponding working condition.

[0050] In step S4 above, several candidate locations are selected, each candidate location has several modes, and each mode has an acoustic modal frequency. Various acoustic modal frequencies With motor vibration excitation frequency The differences between the selected locations are calculated, and the average of these differences is obtained. That is, each candidate location corresponds to a single average difference. The magnitudes of the various average differences are compared, and the candidate location with the largest average difference is taken as the optimal noise reduction location for the corresponding working condition. In other words, under this working condition, when the sound-absorbing panel 31 is located at the optimal noise reduction location, the noise generated by resonance can be reduced to the greatest extent.

[0051] By repeating the above process, the optimal noise reduction position can be obtained for each different working condition. When the motor is working under different conditions, adjusting the sound-absorbing plate to the corresponding optimal noise reduction position can effectively reduce the noise generated by the motor.

[0052] Compared with existing technologies, this invention can adjust the axial position of the sound-absorbing plate structure in the end cavity according to changes in the motor's operating conditions, thereby altering the acoustic mode frequency of the end cavity and preventing resonance noise caused by coupling between motor vibration excitation and the motor end cavity. This effectively improves the sound quality of existing motors. Theoretically, the motor noise reduction design method of this invention can reduce motor operating noise by more than 5 dB.

[0053] Based on the above solution, the motor noise reduction design method of the present invention further includes:

[0054] S1. Obtain the motor vibration excitation frequency under various operating conditions of the motor body. i represents the operating condition number, and j represents the vibration excitation frequency number. Motor vibration excitation frequency. It is the natural frequency of the motor excluding the end caps, and the motor vibration excitation frequency. The closer the frequencies are, the easier it is for resonance to occur. Under a specific operating condition, a primary vibration excitation frequency is selected as the motor vibration excitation frequency.

[0055] S2. Design the motor end cover structure based on the motor body dimensions, and obtain the motor end cover modal frequency B. k k is the corresponding modal order number; determine the modal frequency B of the motor end cover. k With motor vibration excitation frequency If the first difference between the two values ​​is less than the first threshold, then redesign the motor end cover structure; otherwise, proceed to step S3.

[0056] In step S2, the overall structure of the end cap is designed first. After the end cap itself meets the requirements, the subsequent steps S3, S4, and S5 are carried out. The overall sequence of the entire design process is S1→S2→S3→S4→S5.

[0057] In step S2, the modal frequency B of the motor end cover is obtained. k The motor end cover 1 has several modes, and the corresponding motor end cover mode frequency B for each mode is... k With motor vibration excitation frequency The difference is calculated; the closer the difference, the easier it is for resonance to occur. Only the motor end cover modal frequency B corresponding to each mode is considered. k With motor vibration excitation frequency Only when the first difference is greater than the first threshold does the motor end cover 1 meet the requirements, and only then will the end cover be analyzed according to steps S3, S4, and S5.

[0058] Specifically, the first threshold in this invention is 6Hz; the second threshold is 3Hz.

[0059] The present invention also provides a noise-reducing motor end cover, combined with Figure 1 , Figure 2 , Figure 7 , Figure 8 , Figure 9 The noise-reducing motor end cover includes a motor end cover 1 and a sound-absorbing component 3; combined with Figure 6 The motor end cover 1 is fixedly installed on the motor body 2 to form the motor as a whole. The output shafts of the motor end cover 1 and the motor body 2 are located at different ends.

[0060] Combination Figure 3 , Figure 4 , Figure 5The sound-absorbing component 3 includes a sound-absorbing plate 31, which is slidably mounted on the motor end cover 1. The sound-absorbing plate 31 can slide and adjust its position axially to change the volume of the cavity at the motor end. The radius of the sound-absorbing plate 31 is slightly smaller than the inner radius of the motor end cover 1. The sound-absorbing plate 31 can be axially translated within the inner cavity of the motor end cover 1. By adjusting the axial position of the sound-absorbing plate 31, the volume of the cavity at the motor end can be changed, and the acoustic modal frequency... Primarily related to the size of the cavity, this invention adjusts the cavity volume by changing the position of the sound-absorbing plate 31 inside the motor end cover 1, thereby changing the acoustic modal frequency. The above-mentioned motor noise reduction design method has provided a method for determining the optimal noise reduction position under various operating conditions. When the motor is working under different operating conditions, the sound-absorbing plate 31 is adjusted to the optimal noise reduction position corresponding to the operating condition to achieve an effective noise reduction effect.

[0061] Combination Figure 3 , Figure 4 , Figure 5 In some embodiments, the sound-absorbing assembly 3 includes an adjusting rod 32, which is vertically fixed to the sound-absorbing plate 31 and slidably mounted on the motor end cover 1 along the axial direction. The adjusting rod 32 and the motor end cover 1 cooperate with each other to serve as guides.

[0062] Specifically, the adjusting rod 32 is fixedly installed at the center of the sound-absorbing plate 31, and extends through the motor end cover 1. Having one adjusting rod 32 is a preferred embodiment; however, multiple adjusting rods can also be arranged symmetrically at the center. All these specific embodiments should be included within the scope of protection of this invention.

[0063] Specifically, in combination Figure 4 The sound-absorbing panel 31 provided by the present invention is a flat plate with several through holes disposed on its surface, and the surface of the sound-absorbing panel 31 is covered with sound-absorbing material. A flat plate is a preferred embodiment for the sound-absorbing panel 31, but the sound-absorbing panel 31 can also adopt a structure with an undulating shape.

[0064] Specifically, in combination Figure 2 , Figure 6 , Figure 8 , Figure 10 , Figure 11 , Figure 12The adjusting rod 32 of this invention has a threaded section on its outer surface. The controller 4 controls the output end of the motor 5 to rotate, and the motor 5 then drives the nut 51 to rotate, thereby driving the adjusting rod 32 to move. The nut 51 is fitted onto the threaded section of the adjusting rod 32. The inner wall of the nut 51 has an internal thread, and the outer wall of the nut 51 has a ring of teeth for meshing with the gear disc 52 at the output end of the motor 5. The gear disc 52 is fixed to the output end of the motor 5. The gear disc 52 rotates with the output end of the motor, thereby driving the nut 51 to rotate. The nut 51 drives the adjusting rod 32 to rotate. The axial position of the nut 51 remains fixed, and axial displacement occurs when the adjusting rod 32 rotates relative to it. The controller sets the optimal axial noise reduction position of the porous sound-absorbing plate structure on the motor end cover 1 for each operating condition of the motor. When the motor is running, the axial position of the porous sound-absorbing plate structure is automatically adjusted according to the operating condition.

[0065] The motor vibration excitation frequency under the first operating condition was determined using a calculation program. The acoustic modal frequencies of the sound-absorbing plate at different axial positions aL / N in the end cavity, where a = 1, 2, 3...N A comprehensive permutation and combination comparison analysis was performed, eliminating combinations with similar frequencies. The average frequency interval of the remaining combinations was calculated, and the combination with the largest average interval was selected to determine the axial position of the porous sound-absorbing plate in the end cavity under this combination. At this point, the optimal axial position of the porous sound-absorbing plate in the end cavity under the first operating condition of the motor can be obtained. Similarly, the calculation program was used to sequentially calculate the main vibration excitation frequencies under the second, third, ..., i-th operating conditions of the motor. The acoustic modal frequencies of the motor end cavity when the sound-absorbing plate is located at different axial positions of the end cavity. By conducting a full permutation and combination comparative analysis, the optimal axial position of the porous sound-absorbing plate in the end cavity was obtained for each operating condition of the motor.

[0066] Compared with existing technologies, the noise-reducing motor end cover of this invention can adjust the axial position of the sound-absorbing plate structure in the end cavity according to changes in the motor's operating conditions, thereby changing the acoustic mode frequency of the end cavity. This prevents resonance noise caused by coupling between motor vibration excitation and the motor end cavity, and effectively improves the sound quality of existing motors. Theoretically, the motor noise-reducing end cover can reduce motor operating noise by more than 5dB.

[0067] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method of motor noise reduction design, characterized in that, include: S3. Divide the axial length L of the inner cavity of the motor end cover into N segments, where N is greater than the number of motor operating conditions. The sound absorption panel is located at an axial position of the motor end cavity The sound modal frequency of the motor end cavity , a The axial position is numbered, b The corresponding modal order is numbered; S4. Under a certain operating condition, the sound-absorbing plate is located at each different axial position. At that time, the frequencies of each of the aforementioned acoustic modes With motor vibration excitation frequency Calculate the second difference. If all the second differences when the sound-absorbing panel is located at a certain position are greater than the second threshold, then that axial position is the candidate position. S5. Calculate the frequency of each acoustic mode at each of the candidate locations. With the vibration excitation frequency of the motor The average difference between the two values ​​is used to determine the optimal noise reduction location for the corresponding operating condition. i For operating condition number, j The vibration excitation frequency is numbered.

2. The motor noise reduction design method according to claim 1, characterized in that, Also includes: S1. Obtain the motor vibration excitation frequency under various operating conditions of the motor body. , i For operating condition number, j Number the vibration excitation frequency; S2. Design the motor end cover structure based on the motor body dimensions and obtain the motor end cover modal frequencies. , k Assign a modal order number to the corresponding mode; determine the modal frequency of the motor end cover. With the vibration excitation frequency of the motor If the first difference between them is less than the first threshold, then the motor end cover structure is redesigned. If not, proceed to step S3.

3. The motor noise reduction design method according to claim 2, characterized in that, The first threshold is 6Hz; the second threshold is 3Hz.

4. A noise-reducing motor end cover, characterized in that, include: Motor end cover (1) is fixedly installed on the motor body (2); The sound-absorbing component (3) includes a sound-absorbing plate (31), which is slidably mounted on the motor end cover (1). The sound-absorbing plate (31) can slide along the axial direction to adjust its position and change the volume of the motor end cavity. The sound-absorbing plate (31) can be adjusted to the corresponding optimal noise reduction position according to the working conditions.

5. The noise-reducing motor end cover according to claim 4, characterized in that, The sound-absorbing component (3) includes an adjusting rod (32), which is vertically fixed to the sound-absorbing plate (31) and is slidably mounted on the motor end cover (1) along the axial direction.

6. The noise-reducing motor end cover according to claim 5, characterized in that, The adjusting rod (32) is fixedly installed at the center of the sound-absorbing plate (31), and the adjusting rod (32) extends through to the motor end cover (1).

7. The noise-reducing motor end cover according to claim 6, characterized in that, The sound-absorbing plate (31) is a flat plate with several through holes on its surface, and the surface of the sound-absorbing plate (31) is covered with sound-absorbing material.

8. The noise-reducing motor end cover according to claim 7, characterized in that, The outer wall of the adjusting rod (32) is provided with a threaded section, and the controller (4) controls the motor (5) to drive the nut (51) to rotate so as to drive the adjusting rod (32) to move; The controller (4) sets the optimal noise reduction position of the sound-absorbing plate (31) for each operating condition of the motor.

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