Silencing device

Abstract

To provide a muffler which is easy to manufacture, can secure a large muffling space and can easily be adjusted according to a frequency.SOLUTION: A muffler attached to a main pipe 2 through which fluid flows includes: an inner pipe 3; and an outer pipe 4 positioned on an outer side of the inner pipe 3. Joint parts 6a and 6b joined to the main pipe 2 are provided at both ends of the outer pipe 4. A caulking part 7 in which an inner face of the outer pipe 4 is brought into contact with an outer face of the inner pipe 3 by pressing the outer pipe 4 in a radial direction toward the inner pipe 3 is provided. A muffling space surround by the inner pipe 3 and the outer pipe 4 is provided between the joint parts 6a and 6b and the caulking part 7. The muffling spaces are side branch chambers 8a and 8b, an end face of the inner pipe 3 and an end face of the main pipe 2 are spaced apart in an axial direction, and entrances 9a and 9b communicated with the side branch chambers 8a and 8b are formed.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a silencer that is joined to a refrigerant pipe, an exhaust pipe, or the like of an air conditioner for a vehicle. [Background technology]

[0002] In automotive air conditioners, mechanical noise from the compressor and noise caused by refrigerant cavitation are transmitted through the piping to the evaporator and then to the driver through the air outlet, or they are transmitted along the piping through the engine compartment and then to the driver via the vehicle body. For this reason, muffler-type silencers or insert-type silencers are installed in the piping of automotive air conditioners. Muffler-type silencers are large and heavy, and brazing them increases costs, so insert-type silencers have become more common in recent years.

[0003] For example, Patent Document 1 describes a device in which spiral fins are provided on the outer surface of an inner tube. In this device, a phase difference occurs due to the difference in the length of the inner and outer flow passages, which causes sound interference and produces a sound-deadening effect, but because the fins are formed into a spiral shape, they are difficult to manufacture, the sound-deadening space cannot be made large, and it is difficult to adjust the flow passage length.

[0004] Patent Document 2 describes a silencer that is inserted into a tubular main body, with a resonator chamber provided between the silencer and the main body, and a flow path in the main body connected to the resonator chamber via a connecting channel. Patent Document 3 also describes a sound-absorbing device in which an outer member surrounding an inner member is a bellows, a cavity is formed between the inner and outer members, and an opening of the inner member is open to the cavity. Both of these are resonance types, and the resonance frequency is determined by the shape of the resonator, making it difficult to adjust according to the frequency of the sound source. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] European Patent Publication EP2138750A1 [Patent Document 2] Patent No. 5785173 specification [Patent Document 3] Japanese Patent Application Laid-Open No. 2005-84693 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made in consideration of the above-mentioned problems of the conventional art, and an object of the present invention is to provide a silencer that is easy to manufacture, can secure a large silencing space, and can be easily adjusted according to frequency. [Means for solving the problem]

[0007] As a means for solving the above problems, the present invention provides: (1) A silencer attached to a main pipe through which a fluid flows, an inner tube and an outer tube located outside the inner tube, The outer pipe has joints at both ends thereof that are joined to the main pipe, a crimping portion is provided where the inner surface of the outer tube comes into contact with the outer surface of the inner tube by pressing the outer tube toward the inner tube in a radial direction; The invention is characterized in that a sound-absorbing space surrounded by the inner pipe and the outer pipe is provided between the joint portion and the crimped portion.

[0008] In the present invention, the fluid that enters the inner pipe from the upstream side of the main pipe passes through the inner pipe and flows out to the downstream side of the main pipe. The sound waves that enter the silencing space surrounded by the outer pipe and the inner pipe from the main pipe are silencing in the silencing space. The silencer of the present invention is easy to manufacture because the silencing space can be formed simply by inserting the inner pipe into the outer pipe, joining the outer pipe to the main pipe, and pressing the outer pipe radially toward the inner pipe. Furthermore, since a sound-absorbing space is provided between the inner pipe and the outer pipe located outside the inner pipe, the cross-sectional area of ​​the sound-absorbing space can be made larger by increasing the diameter of the outer pipe compared to an insert-type sound-absorbing device that is inserted into the main pipe. Furthermore, the length of the silencing space can be easily adjusted in accordance with the frequency of the noise source simply by changing the axial position of the crimped portion of the outer tube.

[0009] (2) The silencing space is a side branch chamber, The end face of the inner pipe and the end face of the main pipe are spaced apart in the axial direction, and an inlet / outlet communicating with the side branch chamber is formed. This feature makes it easy to manufacture the device, since the inlet and outlet of the side branch chamber can be formed simply by separating the end face of the inner pipe from the end face of the main pipe in the axial direction.

[0010] (3) The inner pipe is integral with the main pipe; The silencing space is a side branch chamber, The inner pipe is characterized in that an inlet / outlet communicating with the side branch chamber is formed at a position adjacent to the joint or the crimped portion of the inner pipe. This feature makes it easy to manufacture, since the inner pipe is integral with the main pipe and the inner pipe, in which the inlet and outlet are formed, is simply inserted into the outer pipe and joined.

[0011] (4) The inner pipe is integral with the main pipe; The silencing space is a resonance chamber, An opening communicating with the resonance chamber is formed between the joint portion and the crimped portion of the inner tube. This feature makes it easy to manufacture, since the inner pipe is integral with the main pipe and the inner pipe, having the opening formed therein, can be simply inserted into the outer pipe and joined together.

[0012] (5) The crimped portions are formed at a plurality of locations spaced apart in the axial direction, A resonance chamber or a side branch chamber surrounded by the inner tube and the outer tube, and an opening communicating with the resonance chamber or an entrance / exit communicating with the side branch chamber are formed between the multiple crimped portions. With this feature, since there are multiple crimped portions in the axial direction, the inner tube is stable and does not shift or tilt. [Effects of the Invention]

[0013] According to the invention of claim 1, the silencing space can be formed simply by inserting the inner pipe into the outer pipe, joining the outer pipe to the main pipe, and pressing the outer pipe radially toward the inner pipe, making it easy to manufacture. Furthermore, since a sound-absorbing space is provided between the inner pipe and the outer pipe located outside the inner pipe, the cross-sectional area of ​​the sound-absorbing space can be made larger by increasing the diameter of the outer pipe compared to an insert-type sound-absorbing device that is inserted into the main pipe. Furthermore, the length of the silencing space can be easily adjusted in accordance with the frequency of the noise source simply by changing the axial position of the crimped portion of the outer tube.

[0014] According to the invention of claim 2, the inlet and outlet of the side branch chamber can be formed simply by separating the end face of the inner pipe and the end face of the main pipe in the axial direction, which makes manufacturing easy.

[0015] According to the invention of claim 3, the inner pipe is integral with the main pipe, and it is only necessary to insert the inner pipe, in which the inlet and outlet are formed, into the outer pipe and join them, which makes manufacturing easy.

[0016] According to the invention of claim 4, the inner pipe is integral with the main pipe, and it is only necessary to insert the inner pipe having the opening into the outer pipe and join them, which makes manufacturing easy.

[0017] According to the invention of claim 5, since there are a plurality of crimped portions in the axial direction, the inner tube is stable and does not shift or tilt. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a perspective view of a side branch type silencer according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a longitudinal cross-sectional view of the silencer of FIG. 1. [Figure 3] FIG. 2 is an exploded perspective view showing the silencer of FIG. 1 in a state before being crimped. [Figure 4] FIG. 2 is an enlarged partial view of the silencer of FIG. 1. [Figure 5] FIG. 5 is a perspective view of a side branch type silencer according to a second embodiment of the present invention. [Figure 6] FIG. 6 is a longitudinal cross-sectional view of the silencer of FIG. 5. [Figure 7] FIG. 6 is an exploded perspective view showing the silencer of FIG. 5 in a state before being crimped. [Figure 8] FIG. 6 is a partial enlarged view of the silencer of FIG. 5. [Figure 9] FIG. 10 is a perspective view of a resonance type silencer according to a third embodiment of the present invention. [Figure 10] FIG. 10 is a longitudinal cross-sectional view of the silencer of FIG. 9. [Figure 11] FIG. 10 is an exploded perspective view showing the silencer of FIG. 9 in a state before being crimped. [Figure 12] FIG. 10 is a partial enlarged view of the silencer of FIG. [Figure 13] FIG. 2 is a perspective view showing a modified example of the side branch type silencer of FIG. [Figure 14] FIG. 14 is a longitudinal cross-sectional view of the silencer of FIG. 13. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0020] First Embodiment FIG. 1 shows a silencer 1 according to a first embodiment of the present invention. The silencer 1 is provided in a pipe through which a refrigerant of a vehicle air conditioner flows. Specifically, the silencer is joined to a pipe (hereinafter referred to as a "main pipe") 2 on the outlet side of an evaporator or compressor in a vehicle air conditioner that includes a compressor, a condenser, an expansion valve, and an evaporator (not shown). The main pipe 2 is made of a metal material such as aluminum, but is not limited to this and may also be made of a material such as rubber or synthetic resin. A fluid (hereinafter referred to as a "refrigerant") flows through the main pipe 2 from the upstream side on the left side to the downstream side on the right side in FIG. 1.

[0021] The main pipe 2 consists of a first main pipe 2a on the upstream side and a second main pipe 2b on the downstream side, and the silencer 1 is joined between the downstream end of the first main pipe 2a and the upstream end of the second main pipe 2b.

[0022] As shown in FIGS. 2 and 3, the silencer 1 includes an inner pipe 3 and an outer pipe 4.

[0023] The inner pipe 3 is made of a metal material such as aluminum, and has the same or nearly the same outer diameter and wall thickness as the main pipe 2. The length of the inner pipe 3 is arbitrary, but it is preferable that the length does not interfere with the bending of the main pipe 2 at the location where the inner pipe 3 is installed. The inside of the inner pipe 3 forms a main flow path 5 for the fluid flowing through the main pipe 2. Like the main pipe 2, the inner pipe 3 may be made of a material such as rubber or synthetic resin.

[0024] The outer pipe 4 is made of a metal material such as aluminum, is located outside the inner pipe 3, and has an outer diameter larger than that of the main pipe 2 and the inner pipe 3. The length of the outer pipe 4 is longer than that of the inner pipe 3. The upstream end and downstream end of the outer pipe 4 are reduced in diameter to form a first joint 6a and a second joint 6b that are joined to the downstream end of the first main pipe 2a and the upstream end of the second main pipe 2b, respectively. When the first main pipe 2a and the second main pipe 2b are made of aluminum, the first joint 6a and the second joint 6b at both ends of the outer pipe 4 are joined to the first main pipe 2a and the second main pipe 2b by, for example, brazing.

[0025] The middle of the outer pipe 4 is pressed radially toward the inner pipe 3, for example, from eight directions around the circumference, to form a crimped portion 7 where the inner surface of the outer pipe 4 contacts the outer surface of the inner pipe 3. When forming the crimped portion 7 on the outer pipe 4, it is preferable to hold the inner pipe 3 concentrically with the outer pipe 4 so that the inner pipe 3 does not move.

[0026] A first side branch chamber 8a and a second side branch chamber 8b are defined between the inner pipe 3 and the outer pipe 4, respectively, between the first joint 6a and the crimped portion 7 of the outer pipe 4 and between the second joint 6b and the crimped portion 7 of the outer pipe 4. The upstream end of the inner pipe 3 is spaced axially from the downstream end of the main pipe 2a, forming a first annular inlet / outlet 9a of the side branch chamber 8a. Similarly, the downstream end of the inner pipe 3 is spaced axially from the upstream end of the main pipe 2b, forming a second annular inlet / outlet 9b of the side branch chamber 8b. The position of the crimped portion 7 of the outer pipe 4 determines the lengths of the side branch chambers 8a and 8b.

[0027] Next, the operation of the silencer 1 of this embodiment will be described.

[0028] As shown in Fig. 4, the refrigerant flowing inside the first main pipe 2a flows into the main flow path 5 of the inner pipe 3 at the upstream end of the silencer 1, passes through the inner pipe 3, and flows out into the second main pipe 2b. Sound (mechanical noise of the compressor and noise due to cavitation of the refrigerant) generated from a sound source (not shown) on the upstream side of the silencer 1 propagates downstream along with the refrigerant and enters the first side branch chamber 8a and the second side branch chamber 8b of the silencer 1 from the first inlet / outlet 9a and the second inlet / outlet 9b. Note that the sound source may be located on the downstream side, in which case the silencing effect will be generated on the upstream side.

[0029] Sound waves that enter the first side branch chamber 8a from the inlet / outlet 9a at the upstream end of the inner pipe 3 are reflected by the crimped portion 7 of the side branch chamber 8a and return to the inlet / outlet 9a, where they become out of phase with the sound waves in the inner pipe 3, causing interference and silence. Similarly, sound waves that enter the second side branch chamber 8b from the inlet / outlet 9b at the downstream end of the inner pipe 3 are reflected by the crimped portion 7 of the side branch chamber 8b and return to the inlet / outlet 9b, where they become out of phase with the sound waves in the inner pipe 3, causing interference and silence.

[0030] Here, if the cross-sectional area of ​​the main pipe 2 is S, the cross-sectional area of ​​the side branch chambers 8a and 8b is Ss, the length of the side branch chambers 8a and 8b is l, the frequency of the sound wave is f, and the speed of sound is c, then the transmission loss TL in the silencer 1 is expressed by Equation 1. The length l of the side branch chambers 8a and 8b is the distance from the entrances 9a and 9b to the crimped portion 7.

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[0031] In the silencer 1 of this embodiment, by changing the axial position of the crimped portion 7, the length la of the first side branch chamber 8a and the length lb of the second side branch chamber 8b can be adjusted, thereby increasing the noise reduction effect according to the frequency of the sound source.

[0032] Second Embodiment 5 to 7 show a noise suppressor 1A according to a second embodiment of the present invention. Like the noise suppressor 1 of the first embodiment, the noise suppressor 1A has an outer pipe 4, but the inner pipe 3 is integrated with the main pipe 2, and a first inlet / outlet 9a of a first side branch chamber 8a is formed adjacent to the first joint 6a of the inner pipe 3, and a second inlet / outlet 9b of a second side branch chamber 8b is formed adjacent to the second joint 6b of the inner pipe 3. The first inlet / outlet 9a and second inlet / outlet 9b of the inner pipe 3 are provided adjacent to the first joint 6a and second joint 6b, but may also be provided adjacent to the crimped portion 7.

[0033] As shown in Figure 8, the refrigerant flowing through the upstream main pipe 2 flows into the main flow path 5 of the inner pipe 3 at the upstream end of the silencer 1A, passes through the inner pipe 3, and flows out into the downstream main pipe 2. Sound waves propagating from a sound source (not shown) upstream of the silencer 1A enter the first side branch chamber 8a through the inlet / outlet 9a at the upstream end of the inner pipe 3, are reflected by the crimped portion 7 of the side branch chamber 8a, and return to the inlet / outlet 9a, where they become out of phase with the sound waves in the inner pipe 3, causing interference and silence. Similarly, sound waves entering the second side branch chamber 8b through the inlet / outlet 9b at the downstream end of the inner pipe 3 are reflected by the crimped portion 7 of the side branch chamber 8b, and return to the inlet / outlet 9b, where they become out of phase with the sound waves in the inner pipe 3, causing interference and silence.

[0034] Third Embodiment 9 to 11 show a noise suppressor 1B according to a third embodiment of the present invention. Like the noise suppressor 1 of the first embodiment, the noise suppressor 1B has an outer pipe 4, but the inner pipe 3 is integrated with the main pipe 2, a first resonance chamber 10a and a second resonance chamber 10b are formed between the inner pipe 3 and the outer pipe 4, and a first opening 11a of the first resonance chamber 10a and a second opening 11b of the second resonance chamber 10b are formed in the inner pipe 3.

[0035] 12, the refrigerant flowing inside the upstream main pipe 2 flows into the main flow path 5 of the inner pipe 3 at the upstream end of the silencer 1B, passes through the inner pipe 3, and flows out into the downstream main pipe 2. The energy of sound waves propagated from a sound source (not shown) on the upstream side of the silencer 1B and entered the inner pipe 3 is absorbed and silenced by the first resonance chamber 10a and the second resonance chamber 10b through the first opening 11a and the second opening 11b.

[0036] Here, when the volume of the resonance chamber 10 is V, the cross-sectional area of ​​the opening 11 is Sr, the length of the opening 11 is l, and the sound speed is c, the resonance frequency ωr is expressed by Equation 2.

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[0037] According to the silencers 1, 1A, and 1B of the above embodiments, the silencing space of the side branch chamber 8 or the resonance chamber 10 can be formed simply by inserting the inner pipe 3 into the outer pipe 4, joining the outer pipe 4 to the main pipe 2, and pressing the outer pipe 4 radially toward the inner pipe 3, making manufacturing easy.

[0038] Furthermore, since a silencing space is provided between the inner pipe 3 and the outer pipe 4 located outside the inner pipe 3, the cross-sectional area of ​​the silencing space can be made larger by making the diameter of the outer pipe 4 larger than in an insert-type silencing device that is inserted into the main pipe 2.

[0039] Furthermore, by simply changing the axial position of the crimped portion 7 of the outer tube 4, the length of the silencing space can be easily adjusted in accordance with the frequency of the noise source.

[0040] In particular, according to the first embodiment, the inlet / outlet 9 of the side branch chamber 8 can be formed simply by separating the end face of the inner pipe 3 from the end face of the main pipe 2 in the axial direction, making manufacturing easy.

[0041] According to the second embodiment, the inner pipe 3 is integral with the main pipe 2, and it is only necessary to insert the inner pipe 3 having the inlet / outlet 9 into the outer pipe 4 and join them, which makes manufacturing easy.

[0042] According to the third embodiment, the inner pipe 3 is integral with the main pipe 2, and it is only necessary to insert the inner pipe 3 having the opening 11 formed therein into the outer pipe 4 and join them, which makes manufacturing easy.

[0043] The present invention is not limited to the above-described embodiment, and can be modified and changed within the scope of the gist of the invention as defined in the claims.

[0044] For example, in the first and second embodiments, either the first side branch chamber 8a or the second side branch chamber 8b may be used as the resonating chamber. Also, in the third embodiment, either the first resonating chamber 10a or the second resonating chamber 10b may be used as the side branch chamber.

[0045] 13 and 14, by forming crimped portions 7 in two locations spaced apart in the axial direction, three silencing spaces can be formed, with the central silencing space serving as a resonance chamber 12 communicating with opening 13 and the silencing spaces on both sides serving as side branch chambers 8a and 8b similar to those in the first embodiment. When there are two crimped portions 7 in the axial direction, the inner tube 3 is stable and does not shift or tilt. In this way, the number of crimped portions 7 is not limited to one or two, but can be formed in multiple locations, and a resonance chamber or a side branch chamber can be formed between these crimped portions 7. [Explanation of symbols]

[0046] 1,1A,1B,1C…silencer 2…Supervisor 2a…1st supervisor 2b…Second supervisor 3…Inner tube 4…Outer tube 5…Main flow path 6a...1st joint 6b...Second joint 7...Crimped part 8a...First side branch chamber 8b...Second side branch chamber 9a…1st entrance / exit 9b…Second entrance / exit 10a...First resonating chamber 10b...Second resonant chamber 11a...first opening 11b…Second opening

Claims

1. A silencer attached to a main pipe through which a fluid flows, an inner tube and an outer tube located outside the inner tube, The outer pipe has joints at both ends thereof that are joined to the main pipe, a crimping portion is provided where the inner surface of the outer tube comes into contact with the outer surface of the inner tube by pressing the outer tube toward the inner tube in a radial direction; a sound-absorbing space surrounded by the inner pipe and the outer pipe is provided between the joint portion and the crimped portion; the inner pipe is integral with the main pipe; The silencing space is a side branch chamber, A silencer characterized in that an inlet / outlet communicating with the side branch chamber is formed at a position of the inner pipe adjacent to the joint or the crimped portion.

2. The crimped portions are formed at a plurality of locations spaced apart in the axial direction, 2. The silencer according to claim 1, wherein a resonance chamber or a side branch chamber surrounded by the inner tube and the outer tube, and an opening communicating with the resonance chamber or an entrance / exit communicating with the side branch chamber are formed between the plurality of crimped portions.

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