CN107749704B

CN107749704B - Low-noise direct-current motor and method for reducing electromagnetic noise

Info

Publication number: CN107749704B
Application number: CN201711247661.4A
Authority: CN
Inventors: 雷诗琼
Original assignee: Shenzhen Envision Motor Co ltd
Current assignee: Shenzhen Envision Motor Co ltd
Priority date: 2017-12-01
Filing date: 2017-12-01
Publication date: 2024-09-06
Anticipated expiration: 2037-12-01
Also published as: CN107749704A

Abstract

The application provides a low-noise direct current motor, which relates to the technical field of motors, and comprises a rotor and a stator, wherein the rotor is sleeved in the stator, the rotor comprises an armature core, an armature groove for placing an armature winding is formed in the armature core, the stator comprises magnetic poles, and the magnetic poles are arranged on the inner side wall of the stator; the ratio of the slot depth of the armature slot to the thickness of the pole is between 1.7 and 3. The low-noise direct current motor provided by the application can be used for relieving the technical problem that the electromagnetic noise of the low-noise direct current motor in the prior art is difficult to reduce. The application also provides a method for reducing electromagnetic noise of the low-noise direct current motor.

Description

Low-noise direct-current motor and method for reducing electromagnetic noise

Technical Field

The invention relates to the technical field of motors, in particular to a low-noise direct current motor. The invention also relates to a method for reducing electromagnetic noise of the low-noise direct-current motor.

Background

In the development process of the motor, reducing the noise of the motor in operation has been a key point and a difficult point of development for a long time. In particular motors used in furniture, household appliances, the customer motor is very conscious of the decibel number of the sound made during operation. At present, the decibel of the working noise of the motor is one of indexes for measuring the performance of the motor besides indexes such as rated power and rated torque.

Noise reduction of the motor may be achieved by using a silencer such as a silencer cover, silencer casing, etc. However, this method has limited noise reduction and is not suitable for use in a compact motor installation structure. Therefore, to reduce the noise of the motor, improvements are made in the internal structure of the motor. This requires an analysis of the cause of motor noise. Because of the complex structure of the motor, it is also difficult to find the source of noise.

Specifically, the basic structure of the direct current motor is: stator, rotor, commutator, brush and casing. After extensive research, the following results are achieved in the art: for a direct current motor, the main three sources of noise are: mechanical noise, commutator noise and electromagnetic noise are respectively, the research on the former two approaches in the field is more sufficient than the third approach, and the noise reduction means mainly aims at the former two noises.

Wherein, the mechanical noise means that the noise originates from the mechanical structure itself. For example, the mechanical noise may be from bearings on the stator, and if roller bearings are used, reducing the noise may adjust the surface roughness of the inner race, outer race and rollers of the bearing to reduce the noise. If an oil-containing sliding bearing is used, noise reduction can be achieved by improving the lubrication quality of the lubricating oil. Mechanical noise can also come from between the stator and the rotor, i.e. the rotor is not well balanced in static and dynamic. For example, the roundness of the rotor core has large error in processing, the concentricity between the rotor and the stator has large error in assembly, the mass center and the rotation center of the rotor are not coincident, and the rigidity of the rotor shaft is insufficient to cause the rotor shaft to have deflection deformation, and the like.

The noise of the commutator refers to the noise generated by the commutator and the brush in cooperation. The commutator and brushes are prone to sparking during operation, and slight sparking is not readily visible, but can produce noise. The cause of spark generation includes high surface roughness of the commutator, improper angle of the brush segments, excessive tightness of the brush segments, or protruding portions of the brush segments, etc.

The electromagnetic noise is noise from the main magnetic circuit of the stator pole. The main magnetic circuit means that magnetic flux passes from the N pole to the rotor through an air gap, passes through the rotor to another air gap and returns to the S pole. When current passes through the armature winding of the rotor, the energized armature winding generates electromagnetic force in the main magnetic circuit, and the product of the force and the armature radius is called electromagnetic torque. In the main magnetic circuit described above, the magnetic flux of the air gap section is a main cause of electromagnetic noise. The magnetic flux of the air gap section creates a disturbing force that can vibrate both the rotor and stator, both of which cause the motor to produce noise. From the source of electromagnetic noise, it is almost impossible to avoid it, and the size of the air gap can be adjusted only through a lot of experiments.

However, in some occasions requiring strict motor noise, even if the mechanical noise and the commutator noise are improved, the noise of the direct current motor still cannot reach a lower standard, and measures are needed to reduce the electromagnetic noise.

In summary, how to provide a low-noise dc motor, and reduce the noise generated during the operation of the dc motor by reducing the electromagnetic noise is a problem to be solved by those skilled in the art. Based on the above, the present invention provides a dc motor and a method for reducing electromagnetic noise to solve the above technical problems.

Disclosure of Invention

The invention aims to provide a low-noise direct current motor so as to solve the technical problem that electromagnetic noise of the low-noise direct current motor is difficult to reduce in the prior art. Another object of the present invention is to provide a method for reducing electromagnetic noise.

The low-noise direct current motor comprises a rotor and a stator, wherein the rotor is sleeved in the stator, the rotor comprises an armature core, an armature groove for placing an armature winding is formed in the armature core, the stator comprises magnetic poles, and the magnetic poles are arranged on the inner side wall of the stator; the ratio of the slot depth of the armature slot to the thickness of the pole is between 1.7 and 3.

Further, a ratio of a slot depth of the armature slot to a thickness of the magnetic pole is between 2.4 and 2.6.

Further, the ratio of the slot depth of the armature slot to the thickness of the magnetic pole is 2.46.

Further, the thickness of the magnetic pole is 5mm-6mm.

Further, the groove depth of the armature groove is 13mm-14mm.

Further, the armature core has an outer diameter of between 42mm and 43 mm.

Further, the armature slots are arranged in 12 around the armature core annular array.

Further, the magnetic field intensity of the magnetic pole is 76mt-80mt.

Further, the magnetic poles are provided in a pair.

Even if the mechanical noise and the commutator noise are improved, the noise of the direct current motor still cannot reach a lower standard, and measures are needed to reduce the electromagnetic noise. And measures for reducing electromagnetic noise can only start from a structure that the direct current motor finishes electromagnetic energy and mechanical energy conversion. The magnetic flux of the DC motor is the main magnetic flux, and the distribution of the magnetic field lines is from the N pole to the rotor through the air gap and then back to the S pole through the other air gap. The main magnetic flux includes an air gap field, the air gap is annular, and if the magnetic flux vector of the air gap field is decomposed into radial and tangential directions, it is found that the radial vector is a main cause of vibration of the stator, and the tangential vector is a main cause of vibration of the rotor. That is, the radial air-gap field is a major cause of stator noise, and the tangential air-gap field is a major cause of rotor noise. Because the stator has natural frequency, resonance phenomenon occurs when the frequency of electromagnetic force generated by radial air gap magnetic field is close to the natural frequency of the stator, and then electromagnetic noise is very large.

After the reason for the electromagnetic noise is found, the structure of the air gap can be changed by changing the structures of the magnet and the armature core. It has been found through many experiments that the above problems can be alleviated by changing the size of the armature slot and/or the size of the magnetic pole on the armature core. In order to ensure the output power of the motor, the variable parameters are the slot depth of the armature slot and the thickness of the pole. The two can be alternatively changed or simultaneously changed, and experiments and comparison show that the noise can be reduced by increasing the groove depth of the armature groove and/or reducing the thickness of the magnetic pole. And then taking the ratio of the slot depth of the armature slot and the thickness of the magnetic pole as parameters to be changed, the electromagnetic noise of the motor is minimized when the ratio is between 1.7 and 3. The basic premise of the experiment is to ensure that the output force of the motor is unchanged. The method for reducing electromagnetic noise is simple to operate, obvious in effect and high in reference significance.

The method for reducing electromagnetic noise provided by the invention increases the groove depth of the armature groove and reduces the thickness of the magnetic pole so as to reduce the electromagnetic noise of the direct current motor.

Based on the above, compared with the prior art, the invention has the advantage of low electromagnetic noise of the direct current motor during operation, and has important significance for reducing the total noise of the direct current motor.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the description of the embodiments or the prior art will be briefly described, and it is obvious that the drawings in the description below are some embodiments of the present invention, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.

FIG. 1 is a main cut-away view of a low noise DC motor;

fig. 2 is a schematic diagram of the structure of the magnetic poles and armature slots of the low noise dc motor of fig. 1.

Marking: 1-an output shaft; 2-compressing a spring; 3-a commutator; 4-brushes; 5-an electric brush fixing plate; 6-brush lead; 7-a front end cover; 8-a rear end cover; 9-magnetic pole; 10-an armature core; 11-a stator housing; 12-a bearing; 13-an oil-impregnated bearing; 14-a fastener; 15-clamping rings; 16-rubber buckle; 17-armature slots.

Detailed Description

The following description of the embodiments of the present invention will be made apparent and fully in view of the accompanying drawings, in which some, but not all embodiments of the invention are shown. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

In the description of the present invention, it should be noted that, if terms such as "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like are used, the indicated orientation or positional relationship is based on the orientation or positional relationship shown in the drawings, only for convenience of describing the present invention and simplifying the description, and does not indicate or imply that the indicated apparatus or element must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention. Furthermore, the terms "first," "second," "third," and the like, as used herein, are used for descriptive purposes only and are not to be construed as indicating or implying any relative importance.

In the description of the present invention, it should be noted that unless explicitly stated and limited otherwise, the terms "mounted," "connected," and "connected" should be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present invention will be understood in specific cases by those of ordinary skill in the art.

Examples

The invention aims to provide a low-noise direct current motor so as to solve the technical problem that electromagnetic noise of the low-noise direct current motor is difficult to reduce in the prior art.

As shown in fig. 2, in this embodiment, a low noise dc motor is provided, which includes a rotor and a stator, and the rotor is sleeved in the stator. The rotor comprises an armature core, an armature groove 17 for placing an armature winding is formed in the armature core, the stator comprises magnetic poles 9, and the magnetic poles are arranged on the inner side wall of the stator. The ratio of the slot depth (absolute value of the difference between L2 and L3) of the armature slot to the thickness (L1) of the magnetic pole is between 1.7 and 3.

After the reason for the electromagnetic noise is found, the structure of the air gap can be changed by changing the structures of the magnet and the armature core. It has been found through many experiments that the above problems can be alleviated by changing the size of the armature slot and/or the size of the magnetic pole on the armature core. In order to ensure the output power of the motor, the variable parameters are the slot depth of the armature slot and the thickness of the pole. The two can be alternatively changed or simultaneously changed, and experiments and comparison show that the noise can be reduced by increasing the groove depth of the armature groove and/or reducing the thickness of the magnetic pole.

The embodiment also provides a method for reducing electromagnetic noise, which increases the groove depth of the armature groove and reduces the thickness of the magnetic pole so as to reduce the electromagnetic noise of the direct current motor. The two are jointly changed, so that the size of the air gap can be ensured.

And then taking the ratio of the slot depth of the armature slot and the thickness of the magnetic pole as parameters to be changed, the electromagnetic noise of the motor is minimized when the ratio is between 1.7 and 3. The basic premise of the experiment is to ensure that the output force of the motor is unchanged. The method for reducing electromagnetic noise is simple to operate, obvious in effect and high in reference significance.

Further, on the basis of the above embodiment, the ratio of the slot depth of the armature slot to the thickness of the magnetic pole is between 2.4 and 2.6. The noise of the motors with various specifications with the ratio is smaller.

Further, the ratio of the slot depth of the armature slot to the thickness of the magnetic pole is 2.46. By analyzing a small direct current motor which is common in the market at present, the electromagnetic noise is minimum when the ratio of the slot depth of the armature slot to the thickness of the magnetic pole is 2.46.

Specifically, in a small-sized direct current motor which is commonly used in the market at present, the outer diameter L5 of a stator shell is 55mm, and the diameter L4 of an output shaft of a rotor is 8mm. In order to ensure the universality of the motor and the force transmission characteristic of the rotating shaft, the two parameters are not changed. Only the armature core and the magnetic poles are adjusted. The armature core is provided with an armature groove for placing the armature winding, the armature groove is approximately fan-shaped, and the depth of the armature groove and the arc length of the outermost side can influence the winding method and the structure of the armature winding.

When the ratio of the slot depth of the armature slot to the thickness of the magnetic pole is 2.46, further, the thickness of the magnetic pole is 5mm-6mm. Or when the ratio of the groove depth of the armature groove to the thickness of the magnetic pole is 2.46, further, the groove depth of the armature groove is 13mm-14mm.

When the ratio of the groove depth of the armature groove to the thickness of the magnetic pole is 2.46, the thickness of the magnetic pole is 5mm-6mm, after the groove depth of the armature groove is determined, the groove depth of the armature groove is determined according to the ratio, and further, the outer diameter of the armature core is 42 mm-43 mm.

When the ratio of the groove depth of the armature groove to the thickness of the magnetic pole is 2.46, the groove depth of the armature groove is 13mm-14mm, and further, the outer diameter of the armature core is 42mm to 43 mm.

The general idea in the above ratio constraint is to reduce the thickness of the pole and increase the slot depth of the armature slot. After the depth of the armature slot is increased, the outer diameter of the armature core needs to be increased to 42mm to 43mm in order to ensure that the size of the rotating shaft is not changed. Meanwhile, the thickness of the magnetic pole is reduced, so that the total size of the stator is ensured, and the reasonable size of the air gap is also ensured.

On the basis of the above embodiment, when the ratio of the groove depth of the armature groove to the thickness of the magnetic pole is 2.46, the groove depth of the armature groove is about 13.8mm, and the thickness of the magnetic pole is about 5.5 mm. At this time, the outer diameter of the stator housing was 55mm, and the diameter of the output shaft of the rotor was 8mm. Further, the armature slots are arranged in 12 number around the armature core annular array.

On the basis of the embodiment, the magnetic field intensity of the magnetic pole is 76mt-80mt. The magnetic field strength of the magnetic pole and the magnetic pole thinning are positively correlated. However, since the constraint parameter is a ratio of the slot depth of the armature slot to the thickness of the magnetic pole, the slot depth of the armature slot increases as the thickness of the magnetic pole decreases. The armature slot has increased slot depth, so that the number of layers of winding wires wound on the armature slot is increased, the armature slot is matched with thinned magnetic poles, the output torque of the motor is unchanged, the power of the motor is ensured, and meanwhile, the electromagnetic noise of the motor is reduced, thereby reducing the noise of the motor.

Further, on the basis of the above embodiment, only one pair of magnetic poles is provided on the stator. For a small dc motor, the magnetic field strength of a pair of magnetic poles is sufficient. And the two magnetic poles are arc-shaped and are oppositely arranged. And the mechanical noise of the magnetic pole can be avoided.

As shown in fig. 1-2, further on the basis of the above-described embodiment, the low-noise direct current motor in this example comprises a stator and a rotor, the rotor comprising an output shaft 1, the output shaft 1 protruding from a front end cover 7, where there is a bearing 12. The rotor also comprises an armature core 10 formed by laminating a plurality of silicon steel sheets, and each silicon steel sheet is provided with an armature groove 17 for placing an armature winding. The inner wall of the stator housing 11 on the stator has a pair of poles 9. There are snap rings 15 on the upper and lower sides of the bearing 12. The other end of the output shaft 1 is provided with a rear end cover 8, and an oil bearing 13 and a fastener 14 are arranged between the rear end cover 8 and the output shaft 1.

The stator further comprises a commutator 3 and a brush assembly comprising a brush 4 and a brush lead 6, the brush 4 being fixed to a brush-fixing plate 5, a compression spring 2 being provided between the commutator 3 and the brush 4. Since the commutator 3 and the brush 4 are easily thinned after long-time operation, the function of the hold-down spring 2 is to ensure that the commutator 3 and the brush 4 are always kept in contact. The front end cover 7 is connected with the brush fixing plate 5 through a rubber buckle 16.

The embodiment also provides a lifting table, which comprises any one of the low-noise direct current motors.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention.

Claims

1. The low-noise direct current motor comprises a rotor and a stator, wherein the rotor is sleeved in the stator, and the low-noise direct current motor is characterized in that the rotor comprises an armature core, an armature groove for placing an armature winding is formed in the armature core, the stator comprises magnetic poles, and the magnetic poles are arranged on the inner side wall of the stator; the ratio of the slot depth of the armature slot to the thickness of the pole is between 1.7 and 3.

2. The low noise dc motor of claim 1, wherein a ratio of a slot depth of the armature slot to a thickness of the magnetic pole is between 2.4 and 2.6.

3. The low noise dc motor of claim 2, wherein a ratio of a slot depth of the armature slot to a thickness of the magnetic pole is 2.46.

4. A low noise dc motor according to claim 3, wherein the thickness of the poles is 5mm-6mm.

5. A low noise dc motor according to claim 3, wherein the armature slot has a slot depth of 13mm to 14mm.

6. The low noise dc motor according to claim 4 or 5, wherein an outer diameter of the armature core is between 42mm and 43 mm.

7. The low noise dc motor of claim 6, wherein the armature slots are arranged in 12 number around the annular array of armature cores.

8. The low noise dc motor of claim 1, wherein the magnetic poles have a field strength of 76mt to 80mt.

9. The low noise dc motor of claim 1, wherein the poles are provided in a pair.

10. A method for reducing electromagnetic noise, characterized by increasing the slot depth of an armature slot and reducing the thickness of a magnetic pole to reduce the electromagnetic noise of a direct current motor.