High-frequency low-noise high-speed motor rotor

Abstract

The utility model discloses a high-frequency low-noise high-speed motor rotor, which comprises a rotating shaft, a permanent magnet, a permanent magnet protective sleeve and fan blades, the permanent magnet is fixedly sleeved on the rotating shaft, the number P of pole pairs of the permanent magnet is 2, the permanent magnet is formed by overlapping N annular permanent magnet sheets, and N is greater than or equal to 2; the permanent magnet protection sleeve is fixedly sleeved on the outer side wall of the permanent magnet; the fan blade comprises an impeller and 17 blades, the impeller is fixedly arranged on the rotating shaft in a penetrating manner; the rotating shaft, the permanent magnet, the permanent magnet protection sleeve and the impeller are coaxially arranged. According to the utility model, the number of the blades is increased to 17, so that the sound frequency can still be effectively improved under the condition that the rotating speed of the motor is reduced, and the sound frequency is not within 3000Hz-4000Hz which is uncomfortable for people, so that the noise can be effectively eliminated, and the use comfort of the high-speed motor is improved; the number of pole pairs of the permanent magnet is two, so that the iron loss can be reduced, and the use efficiency of the high-speed motor is improved.

Description

Technical Field

[0001] The utility model belongs to the field of motors, and more specifically, relates to a high-frequency and low-noise high-speed motor rotor. Background Art

[0002] A motor is a device that converts electrical energy into mechanical energy using the principle of electromagnetic induction. It is widely used in industrial production and various electrical equipment required for life. High-speed motors usually refer to motors with a speed exceeding 10,000 r / min. Because of their high speed and much smaller size than ordinary power motors, they are connected to the prime mover, eliminating the traditional reduction mechanism, and have a small moment of inertia. Therefore, they have the advantages of high motor power density, effective material saving, high transmission efficiency, low noise, and fast dynamic response. High-speed brushless motors for hair dryers have the advantages of high efficiency and small size, and are particularly suitable for household appliances and personal care industries.

[0003] According to research, the human ear can hear sounds between 20Hz and 20,000Hz, and the most sensitive sound is 3,000Hz to 4,000Hz. When people use household appliances with high-speed motors, such as hair dryers and hand dryers, if the sound frequency of the household appliances is between 3,000Hz and 4,000Hz, the noise produced will make people feel bored and uncomfortable.

[0004] In addition, conventional high-speed motors, due to their relatively high rotation speed, tend to generate relatively high temperatures inside the motor, which can easily cause the permanent magnets to demagnetize. Moreover, the permanent magnets are generally magnetized as a whole structure with a low aspect ratio, resulting in high iron loss, which also reduces the efficiency of the high-speed motor. Utility Model Content

[0005] In response to the above defects or improvement needs of the prior art, the utility model provides a high-frequency and low-noise high-speed motor rotor, the pole pair number of its permanent magnet is 2, which reduces iron loss and improves the working efficiency of the high-speed motor rotor, and the number of blades is 17, which can effectively increase the sound frequency and eliminate noise, thereby improving the comfort of use of the high-speed motor.

[0006] To achieve the above object, according to the utility model, a high-frequency and low-noise high-speed motor rotor is provided, characterized in that it includes a rotating shaft, a permanent magnet, a permanent magnet protective cover and a fan blade, wherein:

[0007] The permanent magnet is hollow and cylindrical in shape, the permanent magnet is fixedly sleeved on the rotating shaft, and the number of pole pairs of the permanent magnet is P=2;

[0008] The permanent magnet is composed of N annular permanent magnet sheets stacked together and all the permanent magnet sheets are fixed together, wherein N≥2;

[0009] The permanent magnet protection cover is hollow and cylindrical in shape, and is fixedly sleeved on the outer side wall of the permanent magnet;

[0010] The fan blade includes an impeller and blades, the impeller is fixedly mounted on the rotating shaft, the number of the blades is 17 and the blades are circumferentially mounted on the outer side wall of the impeller;

[0011] The rotating shaft, the permanent magnet, the permanent magnet protection cover and the impeller are coaxially arranged.

[0012] Preferably, the permanent magnet is made of bonded NdFeB material.

[0013] Preferably, the permanent magnet protection cover is made of metal non-magnetic material.

[0014] Preferably, the permanent magnet protection cover and the permanent magnet are interference fit.

[0015] Preferably, the rotation speed of the rotating shaft is 15000 rpm to 57000 rpm.

[0016] Preferably, the impeller is fixedly mounted on one end of the rotating shaft.

[0017] Preferably, the axial length of the permanent magnet protection cover is not less than the axial length of the permanent magnet, and each end of the permanent magnet does not extend beyond the permanent magnet protection cover.

[0018] Preferably, the impeller comprises an annular wheel body and a plate-shaped wheel end cover, there is a space between the inner wall of the wheel body and the rotating shaft, the wheel end cover is fixedly mounted on the rotating shaft, and all the blades are circumferentially mounted on the wheel body.

[0019] Preferably, a portion of the rotating shaft for mounting the permanent magnet is provided with knurling, and anaerobic glue is provided on the knurling of the portion, and the permanent magnet is adhered to the rotating shaft by the anaerobic glue.

[0020] Preferably, a portion of the rotating shaft for mounting the impeller is provided with knurling and anaerobic adhesive is provided on the knurling of the portion, and the impeller is adhered to the rotating shaft by the anaerobic adhesive.

[0021] In general, the above technical solutions conceived by the utility model can achieve the following beneficial effects compared with the prior art:

[0022] 1) The utility model has a high-frequency, low-noise high-speed motor rotor, which increases the number of blades to 17, and can still effectively increase the sound frequency when the rotation speed is reduced, so that the sound frequency is no longer at the annoying 3000Hz-4000Hz but at a high frequency higher than 4000Hz, thereby effectively eliminating noise and improving the comfort of using the high-speed motor; the pole pair number of the permanent magnet of the utility model is 2, which can reduce iron loss and improve the efficiency of using the high-speed motor. The utility model adds a permanent magnet protective cover to the permanent magnet for protection, so that the permanent magnet will not break when rotating at high speed, ensuring the overall safety of the high-speed motor rotor and the service life of the high-speed motor.

[0023] 2) The utility model provides a high-frequency, low-noise high-speed motor rotor, in which permanent magnet sheets are stacked together to form a permanent magnet, that is, the permanent magnet is divided into N permanent magnet sheets along the axial direction. Firstly, the aspect ratio of the permanent magnet can be effectively increased, and multiple permanent magnet sheets of the permanent magnet are stacked together, which can eliminate the demagnetization of the permanent magnet caused by high temperature and back electromotive force. Secondly, the eddy current loss of the high-speed motor rotor can be reduced, and the iron loss can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is the front view of the utility model;

[0025] Figure 2 It is a three-dimensional diagram of the utility model;

[0026] Figure 3 It is a schematic diagram of the permanent magnet in the utility model. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the utility model more clear, the utility model is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the utility model and are not used to limit the utility model. In addition, the technical features involved in each embodiment of the utility model described below can be combined with each other as long as they do not conflict with each other.

[0028] Reference Figure 1 , Figure 2 , a high-frequency and low-noise high-speed motor rotor, comprising a rotating shaft 1, a permanent magnet 2, a permanent magnet protection cover 3 and a fan blade, wherein:

[0029] The permanent magnet 2 is hollow and cylindrical in shape as a whole. The permanent magnet 2 is fixedly sleeved on the rotating shaft 1, and the pole pair number P of the permanent magnet 2 is 2 (that is, the permanent magnet 2 has 2 pairs of magnetic poles), and the pole pair number of the high-speed motor is also 2. A small pole pair number helps to increase the speed of the high-speed motor and reduce the volume and weight of the high-speed motor. Moreover, the pole pair number P of the permanent magnet 2 is 2, which can effectively reduce the iron loss compared with other multi-pole pairs with a larger pole pair number. Iron loss is divided into eddy current loss and hysteresis loss, which is the most fundamental reason for reducing motor efficiency. Reducing the pole pair number is one of the effective means to improve motor efficiency.

[0030] The permanent magnet 2 is preferably made of bonded NdFeB material, which is a permanent magnet material with very high magnetic properties, and its magnetic energy product is much higher than that of permanent magnet materials such as ferrite and AlNiCo.

[0031] Reference Figure 3 The permanent magnet 2 is composed of N (N≥2) annular permanent magnet sheets 31 stacked together and all the permanent magnet sheets 31 are fixed together, preferably glued together; in this way, the permanent magnet 2 is divided into N permanent magnet sheets 31 along the axial direction, which can improve the aspect ratio of the entire permanent magnet 2 (the larger N is, the larger the aspect ratio of the permanent magnet 2 is), and the multiple permanent magnet sheets 31 of the permanent magnet 2 are stacked together. First, the demagnetization of the permanent magnet 2 caused by high temperature (the speed of the high-speed motor is very high, and when there is load, it is easy to cause high temperature inside the high-speed motor) and back electromotive force (back electroheat generated when the high-speed motor starts and stops) can be eliminated, and second, the eddy current loss of the high-speed motor rotor can be reduced, thereby reducing iron loss.

[0032] The permanent magnet protection cover 3 is hollow and cylindrical in shape. The permanent magnet protection cover 3 is fixedly sleeved on the outer wall of the permanent magnet 2. The permanent magnet protection cover 3 is preferably made of a metal non-magnetic material. The metal non-magnetic material does not affect the spatial distribution of the magnetic field of the permanent magnet 2, and has good mechanical properties, and can well protect the permanent magnet 2. The permanent magnet protection cover 3 and the permanent magnet 2 are preferably interference fit, easy to process, and ensure precision.

[0033] The permanent magnet protection cover 3 can enhance the strength of the permanent magnet 2 and protect the permanent magnet 2 from breaking under high-speed rotation, thereby ensuring the overall safety of the high-speed motor rotor and increasing the service life of the structure.

[0034] The fan blade includes an impeller 4 and blades 5. The impeller 4 is fixedly mounted on the rotating shaft 1. The number of the blades 5 is 17 and the blades 5 are circumferentially installed on the outer side wall of the impeller 4. The impeller 4 is preferably fixedly mounted on one end of the rotating shaft 1.

[0035] The rotating shaft 1, the permanent magnet 2, the permanent magnet protection cover 3 and the impeller 4 are coaxially arranged.

[0036] The rotation speed of the rotating shaft 1 is preferably 15000 rpm to 57000 rpm. When the rotating shaft 1 rotates, the sound frequency generated by the rotation of the fan blades can be at a relatively low rotation speed, which is not 3000Hz-4000Hz, and the sound frequency generated can be a high frequency exceeding 4000Hz, which helps to increase the service life of the high-speed motor, thereby effectively eliminating noise and improving the comfort of using the high-speed motor. Further, the impeller 4 includes an annular wheel body 41 and a plate-shaped wheel end cover 42. There is a space between the inner wall of the wheel body 41 and the rotating shaft 1. The wheel end cover 42 is fixedly mounted on the rotating shaft 1, and all the blades 5 are circumferentially mounted on the wheel body 41. This structure can effectively reduce the weight of the impeller 4 and help the high-speed motor to rotate at high speed.

[0037] According to the sound frequency calculation formula: when the motor rotates at high speed, the sound frequency f generated by the rotation of the fan blades can be expressed as: f=n*N / 60, where n is the speed of the motor in revolutions per minute, and N is the number of blades.

[0038] When the motor speed is at the minimum speed of 15000 rpm, f = 15000 / 60*17 = 4250Hz

[0039] When the motor speed is at the lowest high speed of 57000 rpm, f = 57000 / 60*17 = 161500 Hz

[0040] The impellers 4 currently available on the market have about 11, 13, or 15 blades 5, and at the lowest speed, the frequency is between 3000 Hz and 4000 Hz.

[0041] Furthermore, the axial length of the permanent magnet protection cover 3 is not less than the axial length of the permanent magnet 2 , and each end of the permanent magnet 2 does not exceed the permanent magnet protection cover 3 , so that the permanent magnet 2 can be fully protected.

[0042] Further, the part of the rotating shaft 1 used for mounting the permanent magnet 2 is provided with knurling and anaerobic adhesive is provided on the knurling of the part, and the permanent magnet 2 is adhered to the rotating shaft 1 by the anaerobic adhesive, so that the permanent magnet 2 can be firmly mounted on the rotating shaft 1. The part of the rotating shaft 1 used for mounting the impeller 4 is provided with knurling and anaerobic adhesive is provided on the knurling of the part, and the impeller 4 is adhered to the rotating shaft 1 by the anaerobic adhesive. The inner wall of the impeller 4 is firmly mounted on the rotating shaft 1, thereby improving the pull-out force of the impeller 4.

[0043] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A high-frequency and low-noise high-speed motor rotor, characterized in that: It includes a rotating shaft, a permanent magnet, a permanent magnet protective cover and a fan blade, wherein: The permanent magnet is hollow and cylindrical in shape, the permanent magnet is fixedly sleeved on the rotating shaft, and the number of pole pairs of the permanent magnet is P=2; The permanent magnet is composed of N annular permanent magnet sheets stacked together and all the permanent magnet sheets are fixed together, wherein N≥2; The permanent magnet protection cover is hollow and cylindrical in shape, and is fixedly sleeved on the outer side wall of the permanent magnet; The fan blade includes an impeller and blades, the impeller is fixedly mounted on the rotating shaft, the number of the blades is 17 and the blades are circumferentially mounted on the outer side wall of the impeller; The rotating shaft, the permanent magnet, the permanent magnet protection cover and the impeller are coaxially arranged.

2. A high-frequency, low-noise, high-speed motor rotor according to claim 1, characterized in that: The permanent magnet is made of bonded NdFeB material.

3. A high-frequency, low-noise, high-speed motor rotor according to claim 1, characterized in that: The permanent magnet protective cover is made of metal non-magnetic material.

4. A high-frequency, low-noise, high-speed motor rotor according to claim 1, characterized in that: The permanent magnet protection cover and the permanent magnet are interference fit.

5. A high-frequency, low-noise, high-speed motor rotor according to claim 1, characterized in that: The rotating speed of the rotating shaft is 15000 rpm to 57000 rpm.

6. A high-frequency, low-noise, high-speed motor rotor according to claim 1, characterized in that: The impeller is fixedly mounted on one end of the rotating shaft.

7. A high-frequency, low-noise, high-speed motor rotor according to claim 1, characterized in that: The axial length of the permanent magnet protection cover is not less than the axial length of the permanent magnet, and each end of the permanent magnet does not extend beyond the permanent magnet protection cover.

8. The high-frequency, low-noise, high-speed motor rotor according to claim 1, characterized in that: The impeller comprises an annular wheel body and a plate-shaped wheel end cover. There is a space between the inner wall of the wheel body and the rotating shaft. The wheel end cover is fixedly mounted on the rotating shaft. All blades are circumferentially mounted on the wheel body.

9. The high-frequency, low-noise, high-speed motor rotor according to claim 1, characterized in that: The portion of the rotating shaft used for mounting the permanent magnet is provided with knurling and anaerobic glue is provided on the knurling of the portion, and the permanent magnet is adhered to the rotating shaft by the anaerobic glue.

10. The high-frequency, low-noise, high-speed motor rotor according to claim 1, characterized in that: The portion of the rotating shaft used for mounting the impeller is provided with knurling and anaerobic adhesive is provided on the knurling of the portion, and the impeller is adhered to the rotating shaft by the anaerobic adhesive.

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