CN214998228U

CN214998228U - Jet type vacuum pump silencer

Info

Publication number: CN214998228U
Application number: CN202121644820.6U
Authority: CN
Inventors: 奚灵强; 陈阳; 朱明明
Original assignee: Hunan Zhongfake Pump Industry Co ltd
Current assignee: Hunan Zhongfake Pump Industry Co ltd
Priority date: 2021-07-20
Filing date: 2021-07-20
Publication date: 2021-12-03
Anticipated expiration: 2031-07-20

Abstract

The utility model provides a jet vacuum pump silencer, which comprises a first silencing pipe, a second silencing pipe and a separation piece between the first silencing pipe and the second silencing pipe; a first air inlet hole and a second air inlet hole are formed in the side wall of the first silencing pipe, a bottom plate is hermetically arranged at the bottom of the first silencing pipe, and a liquid discharge hole is formed in the bottom plate; the top of the second silencing pipe is provided with an exhaust hole; the blocking piece is provided with a pressure relief hole and a pressure relief valve; the second air inlet is provided with an air pipe used for conveying compressed air, the air pipe is fixedly connected with an upper injection assembly in the first silencing pipe, an upper air flow conversion chamber and an upper injection channel are formed in the upper injection assembly, the upper air flow conversion chamber is communicated with the air pipe, and the upper injection channel is communicated with the upper air flow conversion chamber, the first silencing pipe and the second silencing pipe respectively. The utility model discloses can make the vacuum pump combustion gas following current to the noise is too big when avoiding the vacuum pump to exhaust.

Description

Jet type vacuum pump silencer

Technical Field

The utility model relates to a vacuum pump field especially relates to an injection formula vacuum pump muffler.

Background

A vacuum pump refers to a device or apparatus for obtaining a vacuum by mechanically, physically, chemically or physico-chemically pumping a pumped container, and thus a vacuum pump is understood to be a means for improving, generating and maintaining a vacuum in a certain closed space.

Due to the special property of the vacuum pump, taking the screw vacuum pump as an example, the pump cavity of the screw vacuum pump is negative pressure (vacuum), and has a suck-back effect on atmospheric pressure. The gas molecules near the exhaust port of the screw vacuum pump are sucked back and then exhausted, so that the air near the exhaust port of the vacuum pump flows back and forth, and a surge phenomenon is generated. Surge flow of the vacuum pump not only consumes power and increases the actual load on the vacuum pump, but also increases the sound generated by gas friction and increases the temperature at the exhaust port of the vacuum pump.

Accordingly, there is a need for a silencer for a jet vacuum pump, which solves or at least alleviates the above-mentioned technical drawbacks of surge flow and excessive noise generation when the vacuum pump exhausts.

SUMMERY OF THE UTILITY MODEL

The utility model mainly aims at providing a jet vacuum pump muffler aims at solving the technical problem that surge flow phenomenon appears in the prior art and produces too big noise.

In order to achieve the above object, the present invention provides a silencer for a jet vacuum pump, comprising a first silencing pipe and a second silencing pipe arranged above the first silencing pipe, wherein the first silencing pipe and the second silencing pipe are isolated by a barrier;

a first air inlet hole and a second air inlet hole are formed in the side wall of the first silencing pipe, wherein the first air inlet hole is used for being communicated with an air outlet of the vacuum pump; the bottom of the first silencing pipe is hermetically provided with a bottom plate, and a liquid discharge hole is formed in the bottom plate; the top of the second silencing pipe is hermetically provided with a cover plate, and the cover plate is provided with an exhaust hole; the blocking piece is provided with a pressure relief hole;

an air pipe for conveying compressed air is installed at the second air inlet, the air pipe extends to the inside of the first silencing pipe, an upper injection assembly is fixedly connected to the inside of the first silencing pipe, an upper air flow conversion chamber and an upper injection channel are formed inside the upper injection assembly, the upper air flow conversion chamber is communicated with the air pipe, and the upper injection channel is communicated with the upper air flow conversion chamber, the first silencing pipe and the second silencing pipe respectively;

a liquid discharge pipe communicated with the first silencing pipe is arranged at the liquid discharge hole, and a liquid discharge valve is arranged on the liquid discharge pipe;

and a pressure relief valve is arranged above the pressure relief hole and is communicated with the first silencing pipe through the pressure relief hole.

Further, the injection assembly includes an inner tube and an outer tube;

an upper airflow conversion part is arranged on the outer wall of the inner pipe, a communication hole is formed in the outer pipe, and the outer pipe is sleeved on the inner pipe;

wherein the upper airflow conversion chamber comprises a chamber which is formed between the upper airflow conversion part and the outer pipe and is communicated with the inside of the inner pipe; one end of the communicating hole is communicated with the upper airflow conversion chamber, and the other end of the communicating hole is communicated with the gas conveying pipe;

the upper injection channel comprises an inner airflow pipeline formed by the outer sleeve arranged on the inner pipe.

Furthermore, the upper airflow conversion part is formed by inwards concave arrangement of the outer wall of the inner pipe, and the cross sectional area between the bottom and the top of the upper airflow conversion part is sequentially reduced from bottom to top; and the top of the upper airflow conversion part is provided with an upper airflow conversion hole, so that the upper airflow conversion chamber is communicated with the inside of the inner pipe through the upper airflow conversion hole.

Further, the outer wall of the inner pipe is provided with sealing parts above and below the upper airflow conversion part to prevent airflow from flowing out from a gap between the inner pipe and the outer pipe.

Further, a sealing ring is arranged on the sealing part in a surrounding mode.

Furthermore, a flow guide rod fixedly connected with the outer pipe is arranged right below the inner pipe, and a flow guide part of the flow guide rod extends into the injection channel.

Further, the flow guide part of the flow guide rod has a conical structure.

Further, the height of the top end of the flow guide part is higher than the communication position of the inner pipe and the upper airflow conversion chamber.

Further, the bottom height of the first air intake hole is lower than the bottom height of the upper injection passage.

Furthermore, a gas collecting pipe is arranged at the first gas inlet, one end of the first gas inlet is communicated with the gas collecting pipe, and the other end of the first gas inlet is communicated with the first silencing pipe;

an exhaust pipe is arranged at the exhaust hole, one end of the exhaust hole is communicated with the exhaust pipe, and the other end of the exhaust hole is communicated with the second silencing pipe;

the inner diameters of the first silencing pipe and the second silencing pipe are larger than the inner diameters of the gas collecting pipe and the gas conveying pipe; the inner diameter of the gas collecting pipe is larger than that of the gas conveying pipe.

Compared with the prior art, the utility model has the advantages of it is following:

the utility model can avoid surge flow phenomenon when the vacuum pump exhausts, reduce exhaust noise and load of the vacuum pump, and reduce temperature of the exhaust port of the vacuum pump; the first silencing pipe and the second silencing pipe are arranged and can only perform gas circulation through a specific channel, so that the direct action of atmospheric pressure and a vacuum pump exhaust port is avoided; the first silencer is provided with the first air inlet hole and the second air inlet hole, the first air inlet hole can collect gas exhausted from a vacuum pump and enable the gas to enter the first silencing pipe, the second air inlet hole can facilitate installation of a pipeline, and compressed air enters a specified position inside the first silencing pipe along the pipeline installed at the second air inlet hole, namely enters the upper air flow conversion chamber; the barrier is provided with the pressure relief hole, and the pressure relief valve is arranged, so that excessive gas in the first silencing pipe can enter the second silencing pipe through the pressure relief valve; by arranging the upper injection assembly and forming the upper airflow conversion chamber and the upper injection channel in the upper injection assembly, compressed air in the air conveying pipe can flow upwards along the upper injection channel after the direction is converted, so that gas exhausted by the vacuum pump is driven to flow upwards in a rapid injection manner, and the gas can continuously flow into the second silencing pipe in a downstream manner; through the arrangement of the pressure relief valve, excessive gas in the first silencing pipe can enter the second silencing pipe through the pressure relief channel; in addition, through setting up outage, fluid-discharge tube, can be with the liquid discharge that separates out in the first muffler to, through setting up the flowing back valve, can be avoided flowing back to cause the influence to the exhaust effect.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.

Fig. 1 is a schematic structural diagram of a silencer of an ejector vacuum pump according to an embodiment of the present invention;

fig. 2 is a schematic structural view of an inner tube according to an embodiment of the present invention;

fig. 3 is a schematic structural view illustrating an outer pipe sleeve disposed on an inner pipe according to an embodiment of the present invention;

fig. 4 is a schematic structural view of a diversion rod according to an embodiment of the present invention.

The reference numbers illustrate: the device comprises a bottom plate 1, a liquid discharge hole 11, a liquid discharge pipe 111, a liquid discharge valve 1111, a first silencing pipe 2, a first air inlet hole 21, a second air inlet hole 22, an upper injection component 3, an upper injection channel 31, an inner pipe 32, an upper air flow conversion part 321, an upper air flow conversion hole 3211, a sealing part 322, a sealing ring 3221, an outer pipe 33, a communication hole 331, a guide rod 34, a guide part 341, a blocking part 4, a pressure relief hole 41, a pressure relief valve 411, a second silencing pipe 5, a cover plate 6, an exhaust hole 61, an air conveying pipe 7, an air collecting pipe 8 and an exhaust pipe 9.

The purpose of the present invention, its functional features and advantages will be further described with reference to the accompanying drawings.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.

It should be noted that all the directional indicators (such as the upper and lower … …) in the embodiments of the present invention are only used to explain the relative position relationship between the components, the motion situation, etc. in a specific posture (as shown in the drawings), and if the specific posture is changed, the directional indicator is changed accordingly.

In addition, descriptions in the present application as to "first", "second", and the like are for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicit to the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature.

Moreover, the technical solutions of the present invention between the various embodiments can be combined with each other, but it is necessary to be able to be realized by a person having ordinary skill in the art as a basis, and when the technical solutions are combined and contradictory or cannot be realized, it should be considered that the combination of the technical solutions does not exist, and the present invention is not within the protection scope of the present invention.

As shown in fig. 1-4, the utility model provides a jet vacuum pump muffler, including first hush pipe 2 and setting up second hush pipe 5 above first hush pipe 2, first hush pipe 2 with second hush pipe 5 keeps apart the setting through separation piece 4, and, first hush pipe 2 with second hush pipe 5 can with separation piece 4 fixed connection. Through setting up first hush pipe 2 and second hush pipe 5 that keep apart each other, can make the air admission and the exhaust of muffler are isolated relatively to ensure that air admission to the exhaust in the muffler can only go on through specific passageway, avoided the direct action of atmospheric pressure and vacuum pump gas vent.

The side wall of the first silencing tube 2 is provided with a first air inlet 21 communicated with the air outlet of the vacuum pump and a second air inlet 22 for compressed air to enter, the compressed air can be provided by an air pump and passes through the second air inlet 22 along a set pipeline to enter a designated area inside the first silencing tube 2, wherein the first air inlet 21 can collect gas exhausted from the vacuum pump and enable the gas to enter the inside of the first silencing tube 2, the second air inlet 22 is mainly used for facilitating pipeline installation, compressed air of the air pump enters a designated position inside the first silencing tube 2 along the installed pipeline, and the air pump refers to a device or an assembly for providing compressed air in the patent.

The bottom of the first silencing pipe 2 is hermetically provided with a bottom plate 1, and the bottom plate 1 is provided with a liquid discharge hole 11; by providing the bottom plate 1, it is possible to prevent the gas entering the first muffling pipe 2 from the vacuum pump from being discharged downward, and by providing the liquid discharge hole 11 in the bottom plate 1, it is possible to facilitate the discharge of the liquid, and it is necessary to provide the liquid discharge hole 11 in the bottom plate 1 because a part of the liquid is separated out after the gas discharged from the vacuum pump enters the first muffling pipe 2.

The top of the second silencing pipe 5 is hermetically provided with a cover plate 6, and the cover plate 6 is provided with an exhaust hole 61; the gas can be discharged from a specific path by providing the cover plate 6 on the top of the muffler pipe, and the gas discharged from the muffler can be uniformly discharged from the gas discharge holes 61 by providing the gas discharge holes 61.

When the air pressure inside the first silencing tube 2 is too high due to excessive air exhausted from the vacuum pump, the inside of the first silencing tube 2 needs to be decompressed, so that the excessive air inside the first silencing tube 2 enters the second silencing tube 5 through the decompression channel, and therefore, the blocking piece 4 is provided with the decompression hole 41.

The second inlet port 22 department installs the gas-supply pipe 7 that is used for carrying compressed air, promptly the one end of gas-supply pipe 7 can with provide compressed air the air pump intercommunication, the other end of gas-supply pipe 7 extends to the inside of first hush pipe 2, and the inside fixedly connected with of first hush pipe 2 goes up injection subassembly 3, the inside of going up injection subassembly 3 is formed with air current conversion room and last injection passage 31, the other end of gas-supply pipe 7 with go up air current conversion room intercommunication, go up injection passage 31 respectively with go up the air current conversion room first hush pipe 2 the second hush pipe 5 intercommunication. It should be understood by those skilled in the art that, since the air pipe 7 extends to the inside of the first muffling pipe 2, as a conventional option, a sealing member may be disposed at the second air intake hole 22, and the sealing member may be disposed between the wall of the air pipe 7 and the wall of the second air intake hole 22, so as to prevent the air in the first muffling pipe 2 from flowing out through the gap between the air pipe 7 and the second air intake hole 22, thereby generating noise. It should be noted that the upper jet assembly 3 is a structure capable of switching the direction of the air flow upward and having an air flow passage; the air pipe 7 extending to the inside of the first silencing pipe 2 is installed, the air pipe 7 is communicated with the upper air flow conversion chamber, the air flow direction of the compressed air can be converted upwards, and the upper air flow conversion chamber is communicated with the upper injection channel 31, so that the converted compressed air can be introduced into the upper injection channel 31; the upper injection channel 31 is communicated with the inside of the first silencing tube 2, so that the gas in the vacuum pump can enter the upper injection channel 31 after entering the first silencing tube 2 along the first air inlet hole 21, and noise caused by reciprocating flow of the gas flow is avoided under the drive of the compressed air; by communicating the upper injection passage 31 with the inside of the second muffling tube 5, the compressed air and the gas generated by the vacuum pump can flow into the inside of the second muffling tube 5 and be discharged from the exhaust hole 61.

Specifically, in order to discharge the liquid inside the muffler, a liquid discharge pipe 111 communicating with the first muffling pipe 2 is installed at the liquid discharge hole 11, that is, one end of the liquid discharge hole 11 communicates with the inside of the first muffling pipe 2, and the other end of the liquid discharge hole 11 communicates with the inside of the liquid discharge pipe 111; for the convenience of operation, and without affecting the silencing effect of the silencer, the drain pipe 111 is provided with a drain valve 1111.

In order to release the pressure of the excessive gas in the first silencing pipe 2, a pressure release valve 411 is installed above the pressure release hole 41, the pressure release valve 411 is communicated with the first silencing pipe 2 through the pressure release hole 41, it is required to know that the gas released by the pressure release valve 411 enters the second silencing pipe 5, it is required to know that the pressure release valve 411 generally comprises a valve head and a valve core, and a shock absorption pad can be arranged in the pressure release valve 411.

The operation mode of the above embodiment may be: because the air pipe 7 is communicated with the upper airflow conversion chamber, compressed air enters the upper airflow conversion chamber through the air pipe 7, and after the air flow direction is converted upwards through the upper airflow conversion chamber, the compressed air enters the upper injection channel 31 communicated with the upper airflow conversion chamber and continuously enters the first silencing pipe 2 along the upper injection channel 31; when the vacuum pump operates, the exhaust port of the vacuum pump is communicated with the first air inlet 21 of the silencer, the air discharged by the vacuum pump can enter the first silencing pipe 2, and because the inside of the first silencing pipe 2 is communicated with the upper air flow injection channel, the air discharged by the vacuum pump can enter the upper air flow injection channel and rapidly flow into the second silencing pipe 5 under the action of compressed air, the reciprocating flow of the air flow can not be generated, the generation of noise is avoided, the load of the vacuum pump is reduced, the temperature of the exhaust port of the vacuum pump is also reduced, and finally, all the air flow entering the second silencing pipe 5 can be discharged along the exhaust hole 61.

When the gas discharged from the vacuum pump is excessive and the gas pressure in the first muffler pipe 2 becomes excessive, the excessive gas may flow from the first muffler pipe 2 into the second muffler pipe 5 along the relief valve 411. Further, since the first muffler pipe 2 and the second muffler pipe 5 can flow gas only through the upper injection passage 31 and the relief valve 411, noise caused by the reciprocation of the gas flow can be effectively avoided.

Since a part of the liquid is separated out from the first muffler pipe 2 by the air flow generated by the vacuum pump, the separated liquid can be discharged to the outside through the liquid discharge hole 11 and the liquid discharge pipe 111, and the liquid discharge valve 1111 is opened only when liquid discharge is required, thereby preventing the air flow in the first muffler pipe 2 from flowing along the liquid discharge pipe 111.

As a preference of the above embodiment, in order to enable the compressed air to flow upward and be injected upward along the upper injection passage 31, the injection assembly includes an inner tube 32 and an outer tube 33; an upper airflow conversion part 321 is arranged on the outer wall of the inner pipe 32, a communication hole 331 is arranged on the outer pipe 33, the outer pipe 33 is sleeved on the inner pipe 32, and the inner pipe and the outer pipe should be fixed with each other.

The upper airflow converting chamber includes a chamber formed between the upper airflow converting part 321 and the outer tube 33 and communicated with the inside of the inner tube 32, that is, the upper airflow converting chamber may be a chamber surrounded by the upper airflow converting part 321 and the outer tube 33; one end of the communication hole 331 is communicated with the upper airflow conversion chamber, and the other end of the communication hole 331 is communicated with the gas pipe 7; the upper injection passage 31 includes an inner airflow channel formed by the outer pipe 33 sleeved on the inner pipe 32; further, the inner pipe 32 extends from the inside of the first muffler pipe 2 into the inside of the second muffler pipe 5, that is, one end of the inner pipe 32 is located inside the first muffler pipe 2, and the other end of the inner pipe 32 passes through the baffle 4 and extends into the inside of the second muffler pipe 5, so that the baffle 4 may be provided with a passage through which the inner pipe 32 passes, and the inner wall of the passage should be sealed as much as possible with the outer wall of the inner pipe 32.

In order to ensure the air flow conversion of the compressed air, the upper air flow conversion part 321 is formed by the outer wall of the inner tube 32 being recessed inward, and the cross-sectional area between the bottom and the top of the upper air flow conversion part 321 is sequentially reduced from bottom to top, so that a chamber can be formed between the upper air flow conversion part 321 and the inner wall of the outer tube 33, and the cross-sectional area between the bottom and the top of the upper air flow conversion part 321 is sequentially reduced from bottom to top, so that the compressed air can conveniently flow upward in the upper air flow conversion chamber; in addition, the top of the upper airflow converting part 321 is provided with an upper airflow converting hole 3211, so that the upper airflow converting chamber is communicated with the inside of the inner tube 32 through the upper airflow converting hole 3211, thereby ensuring that the compressed air can only flow upwards and enter the inside of the inner tube 32.

In order to ensure the sealing performance of the upper air flow conversion chamber, the outer wall of the inner tube 32 is provided with sealing parts 322 above and below the upper air flow conversion part 321 to prevent the air flow from flowing out from the gap between the inner tube 32 and the outer tube 33. Further, a sealing ring 3221 may be disposed around the sealing portion 322.

In order to accelerate the injection speed of the gas in the upper injection channel 31, a guide rod 34 fixedly connected with the outer tube 33 is arranged right below the inner tube 32, and specifically, a fixing member may be extended from the outer tube 33 so as to fix the guide rod 34; the flow guide portion 341 of the flow guide rod 34 extends into the upper injection passage 31. Further, the deflector 341 of the deflector rod 34 has a tapered structure, and the compressed air and the gas exhausted from the vacuum pump can flow upward along the tapered structure of the deflector 341. Specifically, the flow guiding portion may be only conical, and further, referring to fig. 4, in an actual production process, the flow guiding portion 341 may also be bullet-shaped, so that the flow guiding portion has a streamline shape, which is convenient for gas to flow, that is, the upper portion of the flow guiding portion 341 may be conical, the middle portion may be cylindrical, and the lower portion may be inverted conical, but the cross section of the lower end of the flow guiding portion needs to be circular, so as to be engaged with the flow guiding rod. Also, the height of the top end of the deflector 341 may be higher than the height of the communication between the inner pipe 32 and the upper air flow conversion chamber to accelerate the upward flow rate of the compressed air; in addition, when the flow guiding portion 341 has a bullet shape, as an alternative, the entire height of the middle portion of the flow guiding portion 341 may be not higher than the height of the communication portion between the inner tube 32 and the upper airflow converting chamber.

In order to facilitate the gas discharged from the vacuum pump to flow into the upper injection channel 31, especially to make it enter the upper injection channel 31 along the bottom of the upper injection channel 31, the bottom height of the first gas inlet holes 21 is lower than the bottom height of the upper injection channel 31.

In order to communicate the first air inlet 21 with the exhaust port of the vacuum pump, a gas collecting pipe 8 is installed at the first air inlet 21, the gas collecting pipe 8 can communicate the exhaust port of the vacuum pump with the first air inlet 21 of the muffler, one end of the first air inlet 21 is communicated with the gas collecting pipe 8, and the other end of the first air inlet 21 is communicated with the first muffling pipe 2.

In order to facilitate the discharge of the gas in the silencer, an exhaust pipe 9 is installed at the exhaust hole 61, one end of the exhaust hole 61 is communicated with the exhaust pipe 9, and the other end of the exhaust hole 61 is communicated with the second silencing pipe 5.

In addition, the inner diameters of the first silencing pipe 2 and the second silencing pipe 5 can be larger than the inner diameters of the gas collecting pipe 8 and the gas conveying pipe 7 so as to ensure that the interior of the silencer can better bear compressed air and gas discharged by the vacuum pump; also, since the compressed air only assists, the inner diameter of the gas header 8 may be larger than the inner diameter of the gas pipe 7.

Among the above technical solution of the utility model, above only be the utility model discloses a preferred embodiment, not consequently the restriction the utility model discloses a patent range, all be in the utility model discloses a under the technical concept, utilize the equivalent structure transform that the content was done in description and the attached drawing, or direct/indirect application all includes in other relevant technical field the utility model discloses a patent protection scope.

Claims

1. A jet vacuum pump silencer comprises a first silencing pipe and a second silencing pipe arranged above the first silencing pipe, wherein the first silencing pipe and the second silencing pipe are arranged in an isolated mode through a blocking piece;

2. A jet vacuum pump muffler according to claim 1, wherein the jet assembly comprises an inner tube and an outer tube;

3. The silencer of claim 2, wherein the upper air flow converting part is formed by inward recessing of the outer wall of the inner pipe, and the cross-sectional area between the bottom and the top of the upper air flow converting part is sequentially reduced from bottom to top; and the top of the upper airflow conversion part is provided with an upper airflow conversion hole, so that the upper airflow conversion chamber is communicated with the inside of the inner pipe through the upper airflow conversion hole.

4. A silencer for a jet vacuum pump according to claim 2, wherein the outer wall of the inner pipe is provided with sealing portions both above and below the upper gas flow converting portion to prevent gas flow from flowing out of a gap between the inner pipe and the outer pipe.

5. A jet vacuum pump muffler according to claim 4, wherein a sealing ring is provided around the sealing portion.

6. The silencer of claim 2, wherein a guide rod fixedly connected with the outer pipe is arranged right below the inner pipe, and a guide part of the guide rod extends into the injection channel.

7. A jet vacuum pump muffler according to claim 6, wherein the flow guide portion of the flow guide rod has a tapered configuration.

8. A jet vacuum pump muffler according to claim 6, wherein the top end of the flow guide is higher than the communication between the inner pipe and the upper gas flow conversion chamber.

9. A jet vacuum pump muffler according to claim 1, wherein the bottom height of the first air intake hole is lower than the bottom height of the upper jet channel.

10. Ejector vacuum pump silencer according to any of claims 1 to 9,

a gas collecting pipe is arranged at the first gas inlet, one end of the first gas inlet is communicated with the gas collecting pipe, and the other end of the first gas inlet is communicated with the first silencing pipe;

the inner diameters of the first silencing pipe and the second silencing pipe are larger than the inner diameters of the gas collecting pipe and the gas conveying pipe, and the inner diameter of the gas collecting pipe is larger than the inner diameter of the gas conveying pipe.