CN111130259A - Motor and silencer thereof - Google Patents

Abstract

The invention provides a motor and a silencer thereof, wherein the motor silencer comprises a plurality of silencer units, the silencer units are annularly arranged, each silencer unit is provided with a silencing cavity, each silencing cavity is provided with an opening facing the outside of the ring, the silencing cavities are arranged in a trapezoid shape and are enclosed by a first cut-off frequency surface and a second cut-off frequency surface which are oppositely arranged, a front wall and a rear wall which are oppositely arranged and a transition surface, the transition surface is opposite to the opening, and the length of the first cut-off frequency surface is smaller than that of the second cut-off frequency surface. According to the motor and the silencer thereof provided by the invention, as the length of the first cut-off frequency surface is smaller than that of the second cut-off frequency surface, the length of the silencer of the motor is changed within a certain range, so that the noise of a wider frequency band can be eliminated, and the noise reduction requirements of various working conditions of the motor can be met.

Description

Motor and silencer thereof

Technical Field

The invention belongs to the technical field of motors, and particularly relates to a motor and a silencer thereof.

Background

High speed cleaner motors are generally more noisy in everyday industrial applications, and at higher speeds the noise is greater. Therefore, the noise problem is always one of the important problems to be improved and solved for the motor; noise components of the high-speed dust collector motor are mainly divided into pneumatic noise, mechanical noise and electromagnetic noise; the aerodynamic noise generated by the high speed rotation of the motor impeller of the high speed cleaner is much greater than the electromagnetic and mechanical noise of the motor, and is the main noise of this type of motor.

The pneumatic noise of the high-speed dust collector motor can be divided into: 1. as the impeller rotates, the passage of the impeller blades through the diffuser flow passage generates aerodynamic noise (i.e., BPF noise) at the blade passing frequency; 2. the air flow normally flows in the flow passage to form broadband noise. The BPF noise presents a sharp peak characteristic on the noise spectrum of the motor, the characteristic frequency is the product of the rotation frequency of the motor and the number of blades of the impeller, the noise spectrum is distributed by the frequency-doubling peak characteristic such as 1 time BPF noise frequency, 2 times BPF noise frequency and 3 times BPF noise frequency, the BPF noise contributes most in the whole aerodynamic noise of the high-speed dust collector motor, and the BPF noise is the most main noise of the motor.

For the noise problem of the designed high-speed dust collector motor, because the design and design are difficult to operate, the method of actively eliminating noise by changing the shape of the flow channel and the design of the impeller is mostly applied to the noise problem at present, passive noise elimination is carried out, for example, a method of carrying out sound absorption and sound insulation treatment by adopting a sound absorption material and a sound absorption structure and a sound insulation material and a sound insulation structure or a method of carrying out sound elimination treatment on noise in a fixed frequency band by adopting a silencer. The high-speed vacuum cleaner motor noise also has a characteristic that a plurality of working conditions exist in the actual use process of the high-speed vacuum cleaner motor for alternative use, so that the actual BPF noise frequency is changed in a certain frequency range, and the broadband noise silencing treatment is needed when the silencing treatment is carried out aiming at the situation. However, the existing muffler can only perform noise elimination for a single frequency, cannot perform broadband noise elimination, and cannot meet the noise reduction requirements of multiple working conditions of the motor.

Disclosure of Invention

The invention aims to provide a motor silencer to solve the problem that the noise reduction requirement of a motor under various working conditions cannot be met in the prior art.

In order to achieve the purpose, the invention adopts the technical scheme that: the utility model provides a motor silencer, includes a plurality of silencer units, each silencer unit is the cyclic arrangement, every silencer unit all has the anechoic chamber, the anechoic chamber has the opening that sets up towards the ring is outer, the anechoic chamber is trapezoidal setting, just the anechoic chamber is enclosed by relative first cut-off frequency face and the second cut-off frequency face that sets up, relative antetheca and the back wall that sets up and transition surface and forms, the transition surface just sets up the opening, the length of first cut-off frequency face is less than the length of second cut-off frequency face.

In one embodiment, the first cut-off frequency surface and the second cut-off frequency surface are arranged oppositely on one side in the length direction and staggered on the other side in the length direction, so that the silencer is in a right-angled trapezoid shape, and the transition surface is obliquely arranged.

In one embodiment, the first cut-off frequency surface is a flat surface, a semi-circular arc surface, or a polygonal surface.

In one embodiment, the transition surface is a flat surface, a wavy surface, or a stepped surface.

In one embodiment, the front wall and the rear wall are flat surfaces, wavy surfaces or a plurality of semi-circular arc surfaces connected in sequence.

In one embodiment, the first cut-off frequency surface has a length h₁The length of the second cut-off frequency plane is h₂Maximum upper cut-off frequency of the silencer is

The minimum lower cut-off frequency of the silencer is

Where c is the speed of sound.

In one embodiment, the motor muffler further comprises an annular base body, each muffler unit is arranged on the same side of the annular base body, and an avoidance notch for avoiding the winding is formed in the inner wall of the annular base body.

In one embodiment, the motor muffler has at least one mounting hole, wherein one of the muffler units has a first arc-shaped notch, and an adjacent muffler unit has a second arc-shaped notch, the first arc-shaped notch and the second arc-shaped notch combining to form the mounting hole.

The invention also provides a motor, which comprises the motor silencer, a shell, a rotor, a winding, a stator arranged on the periphery of the rotor, and a fixing piece for connecting the shell and the motor silencer, wherein the motor silencer is arranged between the shell and the stator.

In one embodiment, the inside of the outer shell is provided with a mounting column which is convexly arranged, a connecting hole is formed in the mounting column, the motor silencer is provided with a mounting hole for the mounting column to pass through, and the fixing piece passes through the mounting hole and is connected to the inner wall of the connecting hole.

The motor and the silencer thereof provided by the invention have the beneficial effects that: compared with the prior art, the motor silencer comprises a plurality of silencer units which are annularly arranged to be adapted to the periphery of a motor stator, so that noise of air flow at the periphery of the motor stator is reduced. Each muffler unit has a muffling chamber with an opening arranged towards the outside of the ring, from which the air flow enters the muffling chamber. According to the principle of the anti-type silencer, sound waves with specific frequency enter the anti-type silencer, the sound waves are continuously reflected in the anti-type silencer, the phase of the sound waves is opposite to that of incident sound waves, the incident sound waves and the reflected sound waves are mutually counteracted to form a sound pressure node or the amplitude of the incident sound waves is reduced, and therefore the purpose of silencing is achieved, and the specific frequency band is related to the length of the anti-type silencer. In the motor silencer provided by the invention, because the length of the first cut-off frequency surface is smaller than that of the second cut-off frequency surface, the length of the motor silencer is changed within a certain range, so that the noise of a wider frequency band can be eliminated, and the noise reduction requirements of various working conditions of the motor can be met.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise.

Fig. 1 is a first perspective view of a muffler of a motor according to an embodiment of the present invention;

fig. 2 is a second perspective view of a muffler of the motor according to an embodiment of the present invention;

FIG. 3 is a cross-sectional view of a motor muffler according to an embodiment of the present invention;

FIG. 4 is a schematic structural diagram of an anechoic chamber provided in an embodiment of the present invention;

fig. 5 is a perspective view of a first muffler unit according to an embodiment of the present invention;

fig. 6 is a perspective view of a second muffler unit according to an embodiment of the present invention;

FIG. 7 is an exploded view of a motor according to an embodiment of the present invention;

fig. 8 is a sectional view of a motor according to an embodiment of the present invention.

Wherein, in the figures, the respective reference numerals:

1-motor muffler; 11-a muffler unit; 110-an anechoic chamber; 1101 — a first cut-off frequency plane; 1102-a second cut-off frequency plane; 1103-front wall; 1104-a rear wall; 1105-a transition surface; 1106-an opening; 111-a first arc-shaped notch; 112-a second arc-shaped notch; 12-an annular substrate; 121-avoiding the notch; 122-a substrate aperture; 13-mounting holes; 2-a rotor; 3-a stator; 4-a housing; 41-arc ribs; 42-mounting posts; 420-connecting hole; 5-a fixing piece; 6-winding.

Detailed Description

In order to make the technical problems, technical solutions and advantageous effects to be solved by the present invention more clearly apparent, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

It will be understood that when an element is referred to as being "secured to" or "disposed on" another element, it can be directly on the other element or be indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or be indirectly connected to the other element.

It will be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like, as used herein, refer to an orientation or positional relationship indicated in the drawings that is solely for the purpose of facilitating the description and simplifying the description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and is therefore not to be construed as limiting the invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

A motor muffler 1 provided in an embodiment of the present invention will now be described.

Referring to fig. 1 to 3, in one embodiment of the motor muffler 1, the motor muffler 1 includes a plurality of muffler units 11, and each of the muffler units 11 is annularly arranged, so that the entire motor muffler 1 is annularly arranged and can be sleeved on the outer circumference of the stator 3 of the motor to muffle airflow noise generated by the motor. Each muffler unit 11 has a muffling chamber 110 for muffling noise of the airflow, and the muffling chamber 110 has an opening 1106, and the airflow continuously vibrates in the muffling chamber 110 after entering the muffling chamber 110 from the opening 1106, so as to achieve the purpose of muffling. Wherein, the opening 1106 of each silencing cavity 110 is arranged towards the outside of the ring, so that the airflow around the motor stator 3 can enter the silencing cavity 110 for silencing.

Referring to fig. 4, fig. 4 is a schematic structural view of the muffling chamber 110, wherein the muffling chamber 110 is trapezoidal. The surfaces of the muffling chamber 110 are not necessarily flat, and the shape of the chamber formed by combining the surfaces is substantially trapezoidal. The inner wall of the muffling cavity 110 is enclosed by five surfaces, namely a first cut-off frequency surface 1101, a second cut-off frequency surface 1102, a front wall 1103, a rear wall 1104 and a transition surface 1105, and the remaining surface is an opening 1106. First cut-off frequency plane 1101 and second cut-off frequency plane 1102 are disposed opposite, e.g., parallel to each other, front wall 1103 and rear wall 1104 are disposed opposite, e.g., parallel to each other, and transition plane 1105 is disposed opposite opening 1106. Thus, the inflow direction of the air flow is the radial direction of the entire motor muffler 1. The length of the first cut-off frequency surface 1101 is smaller than the length of the second cut-off frequency surface 1102, that is, the length of the first cut-off frequency surface 1101 in the radial direction of the motor muffler 1 is smaller than the length of the second cut-off frequency surface 1102 in the radial direction of the motor muffler 1. According to the principle of the anti-muffler, the noise reduction frequency of the anti-muffler is related to the length of the anti-muffler, when the length of the anti-muffler (such as a quarter wave pipe) is fixed, only sound waves with specific frequency can enter the anti-muffler, and the sound waves are continuously reflected in the anti-muffler to eliminate the noise in the frequency band. The length of the muffling cavity 110 in the flowing direction of the air flow is gradually changed, so that the muffling cavity can be used for noise reduction in a relatively wide frequency band, thereby achieving the purpose of broadband noise reduction without disturbing the air flow.

The motor muffler 1 of the above embodiment includes a plurality of muffler units 11, and the plurality of muffler units 11 are arranged in a ring shape to fit to the outer circumference of the motor stator 3, thereby reducing noise of the airflow at the outer circumference of the motor stator 3. Each muffler unit 11 has a muffling chamber 110, the muffling chamber 110 having an opening 1106 provided toward the outside of the ring, the air flow entering the muffling chamber 110 from the opening 1106. According to the principle of the anti-muffler, only sound waves with specific frequency can enter the muffler, the sound waves are continuously reflected in the muffler, and noise in the frequency band is eliminated, wherein the specific frequency band is related to the length of the muffler. In the motor muffler 1 provided by the present invention, since the length of the first cut-off frequency surface 1101 is smaller than the length of the second cut-off frequency surface 1102, the length of the motor muffler 1 is changed within a certain range, so that the noise in a wider frequency band can be eliminated, and the noise reduction requirements of the motor under various working conditions can be met.

In the muffling cavity 110 of the above embodiment, since the lengths of the first cut-off frequency plane 1101 and the second cut-off frequency plane 1102 are different, the sectional length of the muffling cavity 110 from the first cut-off frequency plane 1101 to the second cut-off frequency plane 1102 is changed continuously, which is equivalent to having a plurality of quarter-wave tubes having different lengths, so that the muffling can be performed over a wide frequency band without affecting the flow of the air stream.

Referring to fig. 3 and 4, in one embodiment of the muffling cavity 110, the first cut-off frequency plane 1101 and the second cut-off frequency plane 1102 are disposed opposite to each other on one side in the length direction and are staggered on the other side in the length direction, so that the muffler is a right-angled trapezoid muffler, wherein the transition plane 1105 is disposed obliquely. And the facing sides of the first cut-off frequency plane 1101 and the second cut-off frequency plane 1102 are both the side of the opening 1106. In this way, when the motor muffler 1 is provided on the outer periphery of the motor stator 3, the length of the muffling chamber 110 in the radial direction can be changed continuously, and broadband muffling can be achieved.

More specifically, referring to fig. 4, the first cut-off frequency plane 1101 and the second cut-off frequency plane 1102 are parallel to each other and are both planar, the front wall 1103 and the rear wall 1104 are parallel to each other and are both planar, and the transition plane 1105 is also planar. The muffling chamber 110 in this embodiment has a simple structure and is easy to manufacture.

In one embodiment of the muffling chamber 110, the first cut-off frequency plane 1101 and the second cut-off frequency plane 1102 are both semi-circular arcs. In this embodiment, the diameter of the semicircular arc surface may be equal to the width d of the first cut-off frequency surface 1101 and the second cut-off frequency surface 1102, so that the upper and lower sides of the variable cross-section muffler are closer to the shape of the wave-length pipe (i.e., the arc surface), and the sound-deadening effect is better. In other embodiments, one of the first cut-off frequency plane 1101 and the second cut-off frequency plane 1102 is a semicircular arc surface, and the other of the first cut-off frequency plane 1101 and the second cut-off frequency plane 1102 is a straight surface or a polytropic surface.

In one embodiment of the muffling cavity 110, the first cut-off frequency plane 1101 and the second cut-off frequency plane 1102 are both polygonal planes. In other embodiments, one of the first cut-off frequency plane 1101 and the second cut-off frequency plane 1102 is a polygonal plane, and the other of the first cut-off frequency plane 1101 and the second cut-off frequency plane 1102 is a straight plane or a semicircular arc plane. Of course, in other embodiments, the first cut-off frequency plane 1101 and the second cut-off frequency plane 1102 may also be triangular planes, wavy planes, etc., and the specific shape is not limited.

In one embodiment of the muffling chamber 110, the transition surface 1105 is a wavy surface, and the wavy direction of the wavy surface can be from the first cut-off frequency plane 1101 to the second cut-off frequency plane 1102, or from the front wall 1103 to the rear wall 1104. In other embodiments, the transition surface 1105 may also be a curved surface, a polygonal surface, a triangular surface, a step shape, etc.

In one embodiment of the muffling chamber 110, the front wall 1103 and the rear wall 1104 are wavy surfaces or a plurality of semi-circular arc surfaces connected in sequence, the wave direction of the wavy surfaces may be from the first cut-off frequency plane 1101, the second cut-off frequency plane 1102, or from the opening 1106 to the transition surface 1105, and in other embodiments, the front wall 1103 and the rear wall 1104 may also be in the shape of an arc surface, a polygonal surface, a triangular surface, a step shape, or the like.

Further, the diameters of the semicircular arc surfaces of the front wall 1103 and the rear wall 1104 are the same as the widths of the first cut-off frequency plane 1101 and the second cut-off frequency plane 1102. In the embodiment, the shape of the variable cross-section silencer is closer to the shape formed by radially overlapping a plurality of quarter wave tubes, the silencing property is better, and the airflow flow is not influenced like the overlapping of the quarter wave tubes.

Wherein, single quarter wave pipe is pipeline formula silencer, has that frequency adaptability is wide, simple structure, characteristics such as narrowband noise elimination, but in the actual industrial application, the operation of machine equipment is changed under most of the circumstances, and along with the change of operating condition, main noise frequency channel changes, the silencer of originally aiming at a operating condition design with probably can't be applicable to another kind of operating condition. The broadband noise elimination can be realized by superposing a plurality of wave tubes with different lengths. However, the overlapping structure of the wavelength tubes is dense, so that the interference on the flow of the airflow is large, and the noise elimination of the airflow is not facilitated. The muffling cavity 110 in fig. 4 has a simple structure, and can be applied to a broadband muffling application scenario of pneumatic noise, and compared with a single quarter-wavelength tube muffler, the muffling cavity 110 has a better broadband muffling effect.

In any of the embodiments of the muffling chamber 110 described above, the first cut-off frequency plane 1101 has a length h₁The second cut-off frequency plane 1102 has a length h₂，h₁The size of the variable cross-section silencer determines the upper silencing cut-off frequency h of the variable cross-section silencer₂The size of the variable cross-section muffler determines the muffling lower cut-off frequency of the variable cross-section muffler. More specifically, the maximum upper cut-off frequency of the muffler is

The minimum lower cut-off frequency of the silencer is

Where c is the speed of sound. Corresponding h can be set according to the requirement of the user on the noise elimination frequency band₁And h₂。

The widths of the first cut-off frequency surface 1101 and the second cut-off frequency surface 1102 are both d, the size of d is equivalent to the diameter of a bypass pipe in a quarter-wave pipe sound attenuation distance formula, and the distance between the first cut-off frequency surface 1101 and the second cut-off frequency surface 1102 is L, that is, the width of the variable cross-section muffler is L. L is>1.5h₂And L is>3d, the variable cross-section silencer can have a wider silencing frequency and a better silencing effect. L is>3d, namely, the variable cross-section silencer can be equivalent to a plurality of quarter wave pipes with continuous and different cavity depths. In addition, when the muffling chamber 110 in the present embodiment is used, for the sound transmission loss of the startup noise of a certain frequency,

wherein m is the ratio of the circular cross-sectional area of the wave-length tube with d as the diameter to the main tube cross-sectional area, i.e.

The ratio of the cross-sectional area of the main pipe,

referring to fig. 5, in one embodiment of the muffler unit 11, the outer wall of the muffler unit 11 is planar or arc-shaped, and the outer wall of the muffler unit 11 is adapted to the internal structure of the outer shell 4. The housing 4 has a plurality of arc ribs 41 inside, and the arc ribs 41 may be similar to the blades of the motor and are spirally distributed around the center of the housing 4. The arc-shaped ribs 41 are interposed between the adjacent muffler units 11, and are structured to separate the adjacent two muffler units 11. The side wall of the muffler unit 11 is matched in shape to the side wall of the arc rib 41 and is also arranged in an arc shape.

Referring to fig. 3 and 6, in one embodiment of the motor muffler 1, the motor muffler 1 has at least one mounting hole 13, and the mounting hole 13 is used for being matched with the outer shell 4 to realize the fixed connection between the outer shell 4 and the motor muffler 1. The number of the mounting holes 13 is not limited herein, and may be two, three, four, etc. More specifically, one of the muffler units 11 has a first arc-shaped notch 111, and the other muffler unit 11 adjacent to the muffler unit 11 has a second arc-shaped notch 112, and the first arc-shaped notch 111 and the second arc-shaped notch 112 are aligned and combined to form one mounting hole 13. The installation hole 13 is provided in this way, without affecting the structure of the muffling chamber 110 inside the muffler unit 11.

Alternatively, the number of the muffler units 11 is not limited herein, and is 12, 14, 16, 18, or the like. The positions of the mounting holes 13 need to be set, and the two adjacent muffler units 11 are respectively provided with a first arc-shaped notch 111 and a second arc-shaped notch 112.

Referring to fig. 2, in one embodiment of the motor muffler 1, the motor muffler 1 includes a plurality of muffler units 11 and an annular base 12, each muffler unit 11 is disposed on the same side of the annular base 12, and the muffler units 11 are arranged in a ring at intervals, so that each muffler unit 11 is integrally fixed on the annular base 12, and the annular base 12 may be plate-shaped. Optionally, the inner wall of the annular base 12 is provided with avoidance notches 121 for avoiding the windings 6, the number of the avoidance notches 121 is the same as that of the windings 6, a certain radial space is required for the windings 6 to be installed, and the avoidance notches 121 are arranged to avoid the windings 6 so as to avoid interference with the windings 6.

Optionally, the annular base 12 is provided with a base hole 122 opposite to the mounting hole 13 for the fixing member 5 to pass through, thereby fixing the motor muffler 1 and the stator 3.

Referring to fig. 7 and 8, the present invention further provides a motor, wherein the motor includes the motor muffler 1 in any of the above embodiments, and the motor further includes a housing 4, a rotor 2, a stator 3, a winding 6, and a fixing member 5. The rotor 2, the stator 3, the motor silencer 1 and the shell 4 are sequentially arranged from inside to outside, the winding 6 is arranged on the stator 3, and the fixing piece 5 is used for fixing the motor silencer 1 and the shell 4.

The motor of the above embodiment employs the motor muffler 1, and the motor muffler 1 includes a plurality of muffler units 11, and the plurality of muffler units 11 are annularly arranged to fit to the outer periphery of the motor stator 3, so as to reduce noise of the airflow at the outer periphery of the motor stator 3. As shown in fig. 8, the airflow flows in the direction of the arrow, and when flowing to the muffler unit 11, the muffler unit 11 reduces noise. Specifically, each muffler unit 11 has a muffling chamber 110, the muffling chamber 110 having an opening 1106 provided toward the outside of the ring, the air flow entering the muffling chamber 110 from the opening 1106. According to the principle of the anti-muffler, only sound waves with specific frequency can enter the muffler, the sound waves are continuously reflected in the muffler, and noise in the frequency band is eliminated, wherein the specific frequency band is related to the length of the muffler. In the motor muffler 1 provided by the present invention, since the length of the first cut-off frequency surface 1101 is smaller than the length of the second cut-off frequency surface, the length of the motor muffler 1 is changed within a certain range, so that the noise in a wider frequency band can be eliminated, and the noise reduction requirements of the motor under various working conditions can be met.

Referring to fig. 7, the housing 4 has arc ribs 41 inside, the number of the arc ribs 41 is not limited here, and when the motor muffler 1 is installed inside the housing 4, the arc ribs 41 are inserted between two adjacent muffler units 11, so as to limit the motor muffler 1 circumferentially and radially. The inside of shell 4 still the arch be provided with erection column 42, erection column 42 is the same with the quantity of mounting hole 13, and when motor silencer 1 installed in the inside of shell 4, during erection column 42 inserted the mounting hole 13 one by one, every erection column 42 all had connecting hole 420, and mounting 5 passes mounting hole 13 and connects in the inner wall of connecting hole 420, makes shell 4 and motor silencer 1 fixed connection. More specifically, the ring-shaped base 12 is formed with a base hole 122, and the fixing member 5 is connected to the inner wall of the connection hole 420 through the base hole 122. For example, the fixing member 5 is a screw member, the coupling hole 420 is a screw hole, and the screw member is coupled to an inner wall of the screw hole through the base hole 122.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.

Claims (10)

1. Motor silencer, its characterized in that: the silencer comprises a plurality of silencer units, each silencer unit is annularly arranged, every silencer unit all has the silencing cavity, the silencing cavity has the opening that sets up towards the ring is outer, the silencing cavity is trapezoidal setting, just the silencing cavity is enclosed by relative first cut-off frequency face and the second cut-off frequency face of setting, relative antetheca and the back wall and the transition surface of setting and forms, the transition surface is just right the opening sets up, the length of first cut-off frequency face is less than the length of second cut-off frequency face.

2. The motor muffler of claim 1, wherein: the first cut-off frequency surface and the second cut-off frequency surface are arranged on one side in the length direction in a right-angle opposite mode, and are arranged on the other side in the length direction in a staggered mode, so that the silencer is in a right-angle trapezoid shape, and the transition surface is arranged in an inclined mode.

3. The motor muffler of claim 1, wherein: the first cut-off frequency surface is a straight surface, a semi-circular arc surface or a polygonal surface.

4. The motor muffler of claim 1, wherein: the transition surface is a flat surface, a wavy surface or a stepped surface.

5. The motor muffler of claim 1, wherein: the front wall and the rear wall are flat surfaces, wavy surfaces or a plurality of semi-circular arc surfaces which are connected in sequence.

6. The motor muffler of any one of claims 1 to 5, wherein: the first cut-off frequency surface has a length h₁The length of the second cut-off frequency plane is h₂Maximum upper cut-off frequency of the silencer is

The minimum lower cut-off frequency of the silencer is

Where c is the speed of sound.

7. The motor muffler of any one of claims 1 to 5, wherein: the motor silencer further comprises an annular base body, the silencer units are arranged on the same side of the annular base body, and an avoidance notch used for avoiding the winding is formed in the inner wall of the annular base body.

8. The motor muffler of any one of claims 1 to 5, wherein: the motor muffler has at least one mounting hole, wherein one of the muffler units has a first arc-shaped notch, and an adjacent muffler unit has a second arc-shaped notch, and the first arc-shaped notch and the second arc-shaped notch combine to form the mounting hole.

9. A motor, characterized in that: the motor muffler including any one of claims 1 to 8, further comprising a housing, a rotor, a winding, a stator provided on an outer periphery of the rotor, and a fixing member connecting the housing and the motor muffler, the motor muffler being provided between the housing and the stator.

10. The motor of claim 9, wherein: the inside of shell has the erection column of protruding setting, have the connecting hole in the erection column, motor muffler has the confession the mounting hole that the erection column passed, the mounting passes the mounting hole and connect in the inner wall of connecting hole.

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