CN219575164U - Scattered suction type silencer - Google Patents

Abstract

The utility model discloses a scattered suction muffler, which comprises a main body assembly, wherein the main body assembly comprises a shell, a lower sealing plate, an air inlet pipe and a mounting pipe, the lower sealing plate is arranged at the bottom of the shell, the air inlet pipe is positioned in the shell, the mounting pipe is fixed at the bottom of the air inlet pipe, an auxiliary assembly is arranged on the main body assembly and comprises a diffusion piece and a sound absorbing piece, the diffusion piece is arranged in the shell, and the sound absorbing piece is arranged in the shell. The utility model has the beneficial effects that: the resistance noise reduction structure such as a porous abrupt interface or a resonant cavity on the pipeline is utilized to enable certain frequency sound waves propagating along the pipeline to generate phenomena such as reflection, interference and the like at the abrupt interface, so as to reduce the intensity of the sound waves, and meanwhile, when the sound waves propagate in the resistive structure such as the porous sound absorption material and the like, the sound waves are subjected to friction and viscous resistance to convert the sound energy into heat energy to be consumed, so that the requirements of noise elimination and noise reduction are met.

Description

Scattered suction type silencer

Technical Field

The utility model relates to the field of silencers, in particular to a scattered suction type silencer.

Background

The silencer used in the air separation equipment fields such as pressure swing adsorption nitrogen production, oxygen production, compressed air drying and the like generally adopts a small-hole silencer, is simple to manufacture and low in cost, but has poor silencing effect, and in order to achieve better silencing effect, people make certain improvement on the structure of the silencer, such as an utility model patent with the name of 200810021382.0 in China, the silencer has the advantages that a fixed baffle is added to the silencer, so that an outer cylinder is divided into a front cavity and a rear cavity, and silencing effect is increased; the inner tube is added to enable the air flow to flow back and meet the silencing effect of the small holes; the annular slotted hole has attractive appearance and better silencing effect compared with the annular slotted hole, but the common silencer has only a single resistance noise reduction function, so that the technical problem of poor broadband noise control during exhaust is solved; the PSA low-decibel silencer combines the resistance noise reduction structure such as abrupt change of the section of the pipeline and the resistance noise reduction structure such as porous sound absorption material and the like to better control broadband noise, and therefore the PSA low-decibel silencer is provided.

Disclosure of Invention

This section is intended to outline some aspects of embodiments of the utility model and to briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section as well as in the description of the utility model and in the title of the utility model, which may not be used to limit the scope of the utility model.

The present utility model has been made in view of the above and/or problems occurring in the prior art of a suction muffler.

Therefore, the utility model aims to solve the technical problem that the broadband noise control is poor when the common silencer only has a single resistance noise reduction function, and therefore, the utility model provides a scattered suction type silencer.

In order to solve the technical problems, the utility model provides the following technical scheme: the scattered suction muffler comprises a main body assembly, a shell, a lower sealing plate, an air inlet pipe and a mounting pipe, wherein the lower sealing plate is arranged at the bottom of the shell;

the auxiliary assembly is arranged on the main body assembly and comprises a diffusion piece and a sound absorbing piece, wherein the diffusion piece is arranged in the shell, and the sound absorbing piece is arranged in the shell.

As a preferable embodiment of the suction muffler according to the present utility model, wherein: the diffusion piece comprises a first diffusion cavity, a second diffusion cavity, a first diffusion inner barrel and a second diffusion inner barrel, wherein the first diffusion cavity is arranged in the shell, the second diffusion cavity is arranged in the shell, the first diffusion inner barrel is arranged in the first diffusion cavity, and the second diffusion inner barrel is arranged in the second diffusion cavity.

As a preferable embodiment of the suction muffler according to the present utility model, wherein: the diffusion piece comprises an upper diffusion plate, a lower diffusion plate, a first diffusion plate and a second diffusion plate, wherein the upper diffusion plate is fixed on the top of the inner wall of the shell, the lower diffusion plate is positioned on the top of the inner wall of the first diffusion cavity, the first diffusion plate is arranged at the bottom of the inner wall of the second diffusion cavity, and the second diffusion plate is positioned on the top of the inner wall of the second diffusion cavity.

As a preferable embodiment of the suction muffler according to the present utility model, wherein: the first diffusion inner barrel thickness: 4mm, the second diffusion inner barrel thickness: 4mm, thickness of the upper diffusion plate, the lower diffusion plate, the first diffusion plate and the second diffusion plate: 6mm.

As a preferable embodiment of the suction muffler according to the present utility model, wherein: the sound absorbing piece comprises a first annular sound absorbing layer and a second annular sound absorbing layer, the first annular sound absorbing layer is arranged between the outer side of the first diffusion inner cylinder and the inner wall of the shell, and the second annular sound absorbing layer is arranged between the outer side of the second diffusion inner cylinder and the inner wall of the shell.

As a preferable embodiment of the suction muffler according to the present utility model, wherein: the sound absorbing piece further comprises a first sound absorbing layer and a second sound absorbing layer, wherein the first sound absorbing layer is arranged between the top of the lower diffusion plate and the bottom of the first diffusion plate, and the second sound absorbing layer is arranged at the top of the second diffusion plate and the top of the upper diffusion plate.

As a preferable embodiment of the suction muffler according to the present utility model, wherein: the sound absorbing piece further comprises sound absorbing cotton and a coconut pad, the sound absorbing cotton is arranged in the first annular sound absorbing layer, the second annular sound absorbing layer, the first sound absorbing layer and the second sound absorbing layer, and the coconut pad is arranged in the first annular sound absorbing layer and the first sound absorbing layer.

As a preferable embodiment of the suction muffler according to the present utility model, wherein: the thickness of the sound absorbing cotton and the coconut cushion are as follows: 50mm.

As a preferable embodiment of the suction muffler according to the present utility model, wherein: the air inlet pipe, the first diffusion inner cylinder, the second diffusion inner cylinder, the upper diffusion plate, the lower diffusion plate, the first diffusion plate and the second diffusion plate are all provided with seamless punching processes.

As a preferable embodiment of the suction muffler according to the present utility model, wherein: the shell, the lower sealing plate, the air inlet pipe and the mounting pipe are integrally formed.

The utility model has the beneficial effects that: the resistance noise reduction structure such as a porous abrupt interface or a resonant cavity on the pipeline is utilized to enable certain frequency sound waves propagating along the pipeline to generate phenomena such as reflection, interference and the like at the abrupt interface, so as to reduce the intensity of the sound waves, and meanwhile, when the sound waves propagate in the resistive structure such as the porous sound absorption material and the like, the sound waves are subjected to friction and viscous resistance to convert the sound energy into heat energy to be consumed, so that the requirements of noise elimination and noise reduction are met.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the drawings that are needed in the description of the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present utility model, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art. Wherein:

fig. 1 is a structural view of a suction muffler.

Fig. 2 is a cross-sectional view of a soundproof cotton structure of the suction muffler.

Fig. 3 is a cross-sectional view of a coconut cushion of a suction muffler.

Detailed Description

In order that the above-recited objects, features and advantages of the present utility model will become more readily apparent, a more particular description of the utility model will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present utility model, but the present utility model may be practiced in other ways other than those described herein, and persons skilled in the art will readily appreciate that the present utility model is not limited to the specific embodiments disclosed below.

Further, reference herein to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic can be included in at least one implementation of the utility model. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments.

Example 1

Referring to fig. 1, a first embodiment of the present utility model provides a suction muffler, which includes a main body assembly 100 and an auxiliary assembly 200, which cooperate to achieve a sound deadening function.

Specifically, the main body assembly 100 includes a housing 101, a lower sealing plate 102, an air inlet pipe 103, and a mounting pipe 104, where the lower sealing plate 102 is disposed at the bottom of the housing 101, the air inlet pipe 103 is located in the housing 101, and the mounting pipe 104 is fixed at the bottom of the air inlet pipe 103.

The top of the lower sealing plate 102 is fixedly connected with the bottom of the shell 101, the air inlet pipe 103 is arranged in the shell 101, the outer side of the air inlet pipe 103 is fixedly connected with the lower sealing plate 102, and the top of the mounting pipe 104 is fixedly connected with the bottom of the air inlet pipe 103.

Specifically, the auxiliary assembly 200 is disposed on the main body assembly 100, and includes a diffusing member 201 and a sound absorbing member 202, wherein the diffusing member 201 is disposed in the housing 101, and the sound absorbing member 202 is disposed in the housing 101.

The diffuser 201 is provided in the housing 101, the sound absorbing member 202 is provided in the housing 101, the sound is diffused by the diffuser 201, and the sound absorbing member 202 dampens the diffused sound.

Example 2

Referring to fig. 1 to 3, this embodiment is based on the previous embodiment, which is a second embodiment of the present utility model.

Specifically, the diffusion member 201 includes a first diffusion chamber 201a, a second diffusion chamber 201b, a first diffusion inner tube 201c, and a second diffusion inner tube 201d, the first diffusion chamber 201a is disposed in the housing 101, the second diffusion chamber 201b is disposed in the housing 101, the first diffusion inner tube 201c is disposed in the first diffusion chamber 201a, and the second diffusion inner tube 201d is disposed in the second diffusion chamber 201b.

The first diffusion cavity 201a is disposed at the inner lower end of the housing 101, the second diffusion cavity 201b is disposed at the inner upper end of the housing 101, the outer side of the first diffusion inner cylinder 201c is fixedly connected to the inner wall of the first diffusion cavity 201a, and the outer side of the second diffusion inner cylinder 201d is fixedly connected to the inner wall of the second diffusion cavity 201b.

Specifically, the diffusion member 201 further includes an upper diffusion plate 201e, a lower diffusion plate 201f, a first diffusion plate 201g and a second diffusion plate 201h, wherein the upper diffusion plate 201e is fixed on the top of the inner wall of the housing 101, the lower diffusion plate 201f is located on the top of the inner wall of the first diffusion chamber 201a, the first diffusion plate 201g is disposed at the bottom of the inner wall of the second diffusion chamber 201b, and the second diffusion plate 201h is located on the top of the inner wall of the second diffusion chamber 201b.

The top of the upper diffusion plate 201e is fixedly connected with the top of the inner wall of the shell 101, the top of the lower diffusion plate 201f is fixedly connected with the top of the inner wall of the first diffusion cavity 201a, the bottom of the first diffusion plate 201g is fixedly connected with the bottom of the inner wall of the second diffusion cavity 201b, the top of the second diffusion plate 201h is fixedly connected with the top of the inner wall of the second diffusion cavity 201b, and the first diffusion inner cylinder 201c and the second diffusion inner cylinder 201d are closed through the upper diffusion plate 201e, the lower diffusion plate 201f, the first diffusion plate 201g and the second diffusion plate 201h to form the first diffusion cavity 201a and the second diffusion cavity 201b.

Specifically, the first diffusion inner tube 201c has a thickness: 4mm, second diffusion inner barrel 201d thickness: thickness of 4mm, upper diffusion plate 201e, lower diffusion plate 201f, first diffusion plate 201g, and second diffusion plate 201 h: 6mm.

Diameter of first diffusion inner tube 201 c: 450mm, length: 800mm, second diffusion inner tube 201d diameter 450mm, length 300mm, upper diffuser plate 201e, lower diffuser plate 201f, width 450mm, length of first diffuser plate 201g and second diffuser plate 201 h: 650mm. The diameters of the first diffusion inner cylinder 201c, the second diffusion inner cylinder 201d, the upper diffusion plate 201e, the lower diffusion plate 201f, the first diffusion plate 201g and the second diffusion plate 201h are equal to the diameter of the muffler, so that the diffusion area is far larger than the inlet aperture, and the rapid diffusion and discharge of air flow are facilitated.

Example 3

Referring to fig. 1 to 3, a third embodiment of the present utility model is based on the first two embodiments.

Specifically, the sound absorbing member 202 includes a first annular sound absorbing layer 202a and a second annular sound absorbing layer 202b, the first annular sound absorbing layer 202a being disposed between the outside of the first diffusion inner tube 201c and the inner wall of the casing 101, and the second annular sound absorbing layer 202b being disposed between the outside of the second diffusion inner tube 201d and the inner wall of the casing 101.

The first annular sound absorbing layer 202a is disposed between the outer side of the first diffusion inner tube 201c and the inner wall of the casing 101, the second annular sound absorbing layer 202b is disposed between the outer side of the second diffusion inner tube 201d and the inner wall of the casing 101, and the sound discharged from the first diffusion inner tube 201c and the second diffusion inner tube 201d is canceled by the first annular sound absorbing layer 202a and the second annular sound absorbing layer 202 b.

Specifically, the sound absorbing member 202 further includes a first sound absorbing layer 202c and a second sound absorbing layer 202d, the first sound absorbing layer 202c is disposed between the top of the lower diffusion plate 201f and the bottom of the first diffusion plate 201g, and the second sound absorbing layer 202d is disposed between the top of the second diffusion plate 201h and the top of the upper diffusion plate 201 e.

The top and the bottom of the first sound absorbing layer 202c are adhered to the middle of the top of the lower diffusion plate 201f and the bottom of the first diffusion plate 201g, two ends of the first sound absorbing layer 202c are fixedly connected to the inner wall of the shell 101, the bottom and the bottom of the second sound absorbing layer 202d are arranged on the top of the second diffusion plate 201h and the top of the upper diffusion plate 201e, two ends of the second sound absorbing layer are fixedly connected to the inner wall of the shell 101, double sound attenuation is carried out on sound through the first sound absorbing layer 202c and the second sound absorbing layer 202d, and the sound attenuation effect is improved.

Specifically, the sound absorbing member 202 further includes sound absorbing cotton 202e and a coconut pad 202f, the sound absorbing cotton 202e is disposed in the first annular sound absorbing layer 202a, the second annular sound absorbing layer 202b, the first sound absorbing layer 202c and the second sound absorbing layer 202d, and the coconut pad 202f is disposed in the first annular sound absorbing layer 202a and the first sound absorbing layer 202 c.

The first annular sound-absorbing layer 202a and the second annular sound-absorbing layer 202b are internally provided with the sound-absorbing cotton 202e and the coconut cushion 202f, the first sound-absorbing layer 202c is provided with the sound-absorbing cotton 202e and the coconut cushion 202f, and the sound-absorbing cotton 202e is overlapped, so that the sound effect is better, and the second sound-absorbing layer 202d is provided with the sound-absorbing cotton 202e to enable sound attenuation to be more perfect.

Specifically, the thicknesses of the sound absorbing cotton 202e and the coconut pad 202f are: 50mm.

The same thickness arrangement saves production time when the muffler is produced in quantity, the sound absorbing cotton 202e and the coconut cushion 202f are made of polyester sound absorbing cotton and natural coconut cushion, the natural coconut cushion is moderate in elasticity and soft and firm, has the characteristics of fatigue resistance, rebound resistance, no deformation and the like, and has higher technical indexes such as compression load, fatigue frequency, bonding strength, ageing resistance, constant pressure permanent deformation and the like, and can better meet the requirements in all aspects when being used as a sound absorbing material, and sound absorbing layers with different intervals can attenuate and interfere noise with different frequencies, so that the broadband noise reduction effect is achieved. 100% polyester fiber sound-absorbing cotton is subjected to high-technology hot pressing and is formed in a cocoon cotton shape, the sound-absorbing coefficient reaches 0.94 in the noise range of 125-4000 HZ, and good material stability is ensured, the sound-absorbing cotton cannot expand or shrink due to temperature change, and the high elasticity is never broken under the impact of huge external force.

Specifically, seamless punching is performed on the air inlet pipe 103, the first diffusion inner cylinder 201c, the second diffusion inner cylinder 201d, the upper diffusion plate 201e, the lower diffusion plate 201f, the first diffusion plate 201g and the second diffusion plate 201 h.

The exhaust holes formed in the walls of the first diffusion inner barrel 201c and the second diffusion inner barrel 201d are combined through the resistive sound absorbing and noise reducing material and the resistive sound absorbing and noise reducing structure, the purpose of better controlling high-strength broadband noise generated during air flow emptying is achieved, the upper diffusion plate 201e, the lower diffusion plate 201f, the first diffusion plate 201g and the second diffusion plate 201h are porous metal sheets, a plurality of evenly distributed round holes are formed in the metal sheets, the moving speed of sound waves is changed and attenuated through mutation and friction damping of the small holes, the noise reducing effect is achieved, edges of the porous pore plates are welded with the inner wall of the barrel, and the structural strength of the pore plates is enhanced.

Specifically, the housing 101, the lower seal plate 102, the air inlet pipe 103, and the mounting pipe 104 are integrally formed.

The integrated forming speed is high, the laser beam is only required to be used for cutting along the outline of an object, the whole section does not need to be scanned, so the forming speed is high, the integrated forming device is commonly used for processing large-sized parts with simple internal structures, the prototype has high precision, small buckling deformation, the prototype can bear the temperature of up to two hundred ℃ and has high hardness and good mechanical property, the supporting structure does not need to be designed and manufactured, the cutting processing can be performed, the waste is easy to strip, the post-curing treatment is not required, the prototype with large size can be manufactured, the raw material price is low, the prototype manufacturing cost is low, and the integrated forming device is suitable for rapid mass production.

When in use, the air outlet pipe is connected through the mounting pipe 104, sound air flow enters the air inlet pipe 103, the air flow enters the upper diffusion plate 201e, the lower diffusion plate 201f, the first diffusion plate 201g and the second diffusion plate 201h to the first diffusion inner cylinder 201c and the second diffusion inner cylinder 201d to form a first diffusion cavity 201a and a second diffusion cavity 201b, the diffusion diameter of the first diffusion inner cylinder 201c on the first diffusion cavity 201a and the second diffusion inner cylinder 201b, the diffusion diameter of the lower diffusion plate 201f on the second diffusion inner cylinder 201d, the diffusion diameter of the first diffusion plate 201g and the diffusion diameter of the second diffusion plate 201h are equal to the diameter of the muffler, the diffusion area is far larger than the air inlet caliber, the quick diffusion and the discharge of the air flow are convenient, a plurality of evenly distributed exhaust holes are arranged on the walls of the first diffusion inner cylinder 201c, the second diffusion inner cylinder 201d and the air inlet pipe 103, the air is diffused to the periphery, the speed and the direction of the air flow are changed, the impact strength of air flow to the cylinder and the annular diffusion plate is lightened, the air flow is uniformly distributed on the surface of the diffusion plate, the air flow load on unit area is reduced, the upper diffusion plate 201e, the lower diffusion plate 201f, the first diffusion plate 201g and the second diffusion plate 201h are porous metal sheets, a plurality of uniformly distributed round holes are arranged on the metal sheets, the movement speed of sound waves is changed and attenuated by utilizing mutation and friction damping of the small holes, the effect of noise reduction is achieved, the edges of the porous holes are welded with the inner wall of the cylinder, the structural strength of the porous plates is enhanced, one layer of sound-absorbing cotton 202e is arranged in the first annular sound-absorbing layer 202a and the second annular sound-absorbing layer 202b, one layer of coconut cushion 202f is arranged, the first sound-absorbing layer 202c is one layer of sound-absorbing cotton 202e, two layers of coconut cushion 202f are overlapped, the sound-absorbing effect of one layer of sound-absorbing cotton 202e is better, the sound-absorbing effect of the second sound-absorbing layer 202d is more perfect by the arrangement of double-layer cotton 202e, the sound absorbing cotton 202e and the coconut pad 202f are made of polyester sound absorbing cotton and natural coconut pad, the natural coconut pad is moderate in elasticity and soft and firm, has the characteristics of fatigue resistance, rebound resistance, no deformation and the like, has higher technical indexes such as compression load, fatigue frequency, bonding strength, ageing resistance, constant pressure permanent deformation and the like, can well meet the requirements in all aspects as a sound absorbing material, can attenuate and interfere noise with different frequencies at different intervals, achieves the effect of broadband noise reduction, and 100% polyester fiber sound absorbing cotton is subjected to high-technology hot pressing and is composed of cocoon cotton shapes, the sound absorbing coefficient reaches 0.94 in the range of 125-4000 HZ noise, and the high elasticity is never broken under the impact of huge external force.

It should be noted that the above embodiments are only for illustrating the technical solution of the present utility model and not for limiting the same, and although the present utility model has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solution of the present utility model may be modified or substituted without departing from the spirit and scope of the technical solution of the present utility model, which is intended to be covered in the scope of the claims of the present utility model.

Claims (10)

1. A scattered suction muffler, characterized in that: comprising the following steps:

the main body assembly (100) comprises a shell (101), a lower sealing plate (102), an air inlet pipe (103) and a mounting pipe (104), wherein the lower sealing plate (102) is arranged at the bottom of the shell (101), the air inlet pipe (103) is positioned in the shell (101), and the mounting pipe (104) is fixed at the bottom of the air inlet pipe (103);

the auxiliary assembly (200) is arranged on the main body assembly (100) and comprises a diffusion piece (201) and a sound absorbing piece (202), wherein the diffusion piece (201) is arranged in the shell (101), and the sound absorbing piece (202) is arranged in the shell (101).

2. The suction muffler of claim 1, wherein: the diffusion piece (201) comprises a first diffusion cavity (201 a), a second diffusion cavity (201 b), a first diffusion inner barrel (201 c) and a second diffusion inner barrel (201 d), wherein the first diffusion cavity (201 a) is arranged in the shell (101), the second diffusion cavity (201 b) is arranged in the shell (101), the first diffusion inner barrel (201 c) is arranged in the first diffusion cavity (201 a), and the second diffusion inner barrel (201 d) is arranged in the second diffusion cavity (201 b).

3. The suction muffler as defined in claim 2, wherein: the diffusion piece (201) comprises an upper diffusion plate (201 e), a lower diffusion plate (201 f), a first diffusion plate (201 g) and a second diffusion plate (201 h), wherein the upper diffusion plate (201 e) is fixed on the top of the inner wall of the shell (101), the lower diffusion plate (201 f) is located on the top of the inner wall of the first diffusion cavity (201 a), the first diffusion plate (201 g) is arranged at the bottom of the inner wall of the second diffusion cavity (201 b), and the second diffusion plate (201 h) is located on the top of the inner wall of the second diffusion cavity (201 b).

4. The suction muffler as defined in claim 3, wherein: thickness of the first diffusion inner tube (201 c): 4mm, the thickness of the second diffusion inner barrel (201 d): 4mm, thickness of the upper diffusion plate (201 e), the lower diffusion plate (201 f), the first diffusion plate (201 g) and the second diffusion plate (201 h): 6mm.

5. The suction muffler of claim 4, wherein: the sound absorbing piece (202) comprises a first annular sound absorbing layer (202 a) and a second annular sound absorbing layer (202 b), the first annular sound absorbing layer (202 a) is arranged between the outer side of the first diffusion inner cylinder (201 c) and the inner wall of the shell (101), and the second annular sound absorbing layer (202 b) is arranged between the outer side of the second diffusion inner cylinder (201 d) and the inner wall of the shell (101).

6. The suction muffler of claim 5, wherein: the sound absorbing member (202) further comprises a first sound absorbing layer (202 c) and a second sound absorbing layer (202 d), the first sound absorbing layer (202 c) is arranged between the top of the lower diffusion plate (201 f) and the bottom of the first diffusion plate (201 g), and the second sound absorbing layer (202 d) is arranged between the top of the second diffusion plate (201 h) and the top of the upper diffusion plate (201 e).

7. The suction muffler of claim 6, wherein: the sound absorbing piece (202) further comprises sound absorbing cotton (202 e) and a coconut pad (202 f), the sound absorbing cotton (202 e) is arranged in the first annular sound absorbing layer (202 a), the second annular sound absorbing layer (202 b), the first sound absorbing layer (202 c) and the second sound absorbing layer (202 d), and the coconut pad (202 f) is arranged in the first annular sound absorbing layer (202 a) and the first sound absorbing layer (202 c).

8. The suction muffler of claim 7, wherein: the thicknesses of the sound absorbing cotton (202 e) and the coconut pad (202 f) are as follows: 50mm.

9. The suction muffler as defined in claim 7 or 8, wherein: the air inlet pipe (103), the first diffusion inner cylinder (201 c), the second diffusion inner cylinder (201 d), the upper diffusion plate (201 e), the lower diffusion plate (201 f), the first diffusion plate (201 g) and the second diffusion plate (201 h) are provided with seamless punching processes.

10. A suction muffler as defined in claim 8 or 3, wherein: the air inlet pipe (103) and the mounting pipe (104) are integrally formed.