Silencing device

Abstract

We provide technology that allows for the configuration of sound-dampening devices tailored to on-site conditions by combining different parts. [Solution] The sound-dampening device comprises an air supply side part having a joint at one end for connecting to a noise source and a joint at the other end for connecting to other parts; a branch part having a main pipe section and a branch pipe section, with joints at both ends of the main pipe section and the open end of the branch pipe section for connecting to other parts; a main pipe unit having at least one tubular part; and a branch pipe unit having a joint for connecting to the joint of the branch part and a closing member at the other end. The joints in the air supply side part, the branch part, the tubular part included in the main pipe unit, and the tubular part included in the branch pipe unit are detachable from each other, and at least one of the tubular part included in the main pipe unit and the tubular part included in the branch pipe unit is an expandable part equipped with an expandable / contractable mechanism for expanding and contracting the length of the pipe.

Description

Technical Field

[0001] The present invention relates to a silencing device provided with a side branch.

Background Art

[0002] Conventionally, in air-conditioning ducts, exhaust pipes of internal combustion engines, etc., in order to reduce noise of a specific frequency, it is known to install a side-branch type silencer in a pipeline. The silencing device of Patent Document 1 has openings at both ends, a pipeline in which a first opening of the openings is connected to a noise source, and a side branch provided to project radially outward from a wall surface at a position away from the first opening toward the second opening side in the pipeline. When the wavelength of the noise generated from the noise source is λ, the length of the side branch is set to λ / 4. Further, the lengths from the first opening of the pipeline to the joining position of the silencer and from the second opening of the pipeline to the joining position of the silencer are each set to (2n + 1)λ / 4 (where n is a natural number including 0).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] As mentioned above, the position and length of the side branches of a side-branch type silencer are designed based on the noise frequency λ. However, when such silencers are installed on noise sources such as generators and construction machinery at construction sites, they sometimes cannot be installed due to interference with obstacles that were not apparent during the design phase, such as equipment like rearview cameras, maintenance hatches, and walls and structures at the site.

[0005] Therefore, the objective of this invention is to provide a technology that enables the construction of a sound-dampening device tailored to the specific conditions of the site by combining parts. [Means for solving the problem]

[0006] (1) To solve the above problems, the sound-dampening device of this disclosure is A tubular part having openings at both ends, an air supply side part having a joint at one end for connecting to a noise source and a joint at the other end for connecting to another part, A branch part comprising a main pipe section having openings at both ends, and a branch pipe section branching from the main pipe section and having an opening at the end furthest from the main pipe section, with joints at both ends of the main pipe section and the open end of the branch pipe section for connecting to other parts, A main pipe unit comprising at least one tubular part, the tubular part having a joint at one end for connecting to the joint at the exhaust end of the branch part, A branch pipe unit having at least one tubular part, wherein a joint for connecting to the joint of the branch part is provided at the end of the tubular part on the branch part side, and a closing member is provided at the other end, Equipped with, The aforementioned air intake side part, the aforementioned branching part, the tubular part included in the main pipe unit, and The joints in the tubular parts included in the branch pipe unit are detachable from each other. At least one of the tubular parts included in the main pipe unit and the tubular parts included in the branch pipe unit is an expandable part equipped with an expandable / contractable mechanism for extending or retracting the length of the pipe.

[0007] (2) The sound-dampening device described in (1) above is a part having openings at both ends, and may further include an elbow part in which the orientation of the other end is different from that of one end.

[0008] (3) The sound-dampening device described in (1) or (2) above is The branch pipe unit includes the telescopic part, If the wavelength of the noise generated from the noise source is λ, the length of the branch pipe unit may be set to λ / 4 using the telescopic part.

[0009] (4) The sound-dampening device described in any one of the above items (1) to (3) is such that the branch pipe unit is An elbow part in which the orientation of one end is 180 degrees different from the orientation of the other end, A first telescopic part positioned on the branching part side of the elbow part, A second expandable part positioned on the closing member side of the aforementioned elbow part, Equipped with, If the wavelength of the noise generated from the noise source is λ, the length of the branch pipe unit may be set to λ / 4 using the first and second telescopic parts.

[0010] (5) The sound-dampening device described in any one of the above items (1) to (4) may have an extension mechanism for the telescopic part that includes an inner cylinder and an outer cylinder fitted onto the inner cylinder, and may have a telescopic structure, a screw structure in which the inner cylinder and the outer cylinder are screwed together, or a structure using a bellows-shaped tube.

[0011] (6) The sound-dampening device described in (5) above has an extension mechanism for the extension part, A flange portion provided on the inner cylinder, The flange portion provided on the outer cylinder, a connecting portion that connects the flange portion of the inner cylinder and the flange portion of the outer cylinder, and further includes, the flange portions of the inner cylinder and the outer cylinder may have a triangular outer shape when viewed in the axial direction of the inner cylinder and the outer cylinder.

Advantages of the Invention

[0012] The present invention can provide a technique capable of configuring a silencing device according to the on-site situation by combining parts.

Brief Description of the Drawings

[0013] [Figure 1] FIG. 1 is a perspective view showing an example of a silencing device according to an embodiment. [Figure 2] FIG. 2 is a view showing an example of standardized parts. [Figure 3] FIG. 3 is a view showing the configuration of the air supply side port. [Figure 4] FIG. 4 is a view showing the configuration of the cheese tube. [Figure 5] FIG. 5 is a view showing the configuration of a 45° elbow. [Figure 6] FIG. 6 is a view showing the configuration of a 90° elbow. [Figure 7] FIG. 7 is a view showing the configuration of a 180° elbow. [Figure 8] FIG. 8 is a view showing the configuration of a short telescopic tube. [Figure 9] FIG. 9 is a view showing the configuration of a long telescopic tube. [Figure 10] FIG. 10 is a view showing the configuration of the exhaust side elbow. [Figure 11] FIG. 11 is a view showing the configuration of an end cap. [Figure 12] FIG. 12 is a view showing the configuration of a fixture. [Figure 13] FIG. 1 is a schematic diagram of the silencing device.

Embodiments for Carrying Out the Invention

[0014] Next, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, an exhaust pipe of an internal combustion engine will be described as an example. However, the embodiments described below are illustrative for carrying out the present invention, and the present invention is not limited to the embodiments described below. For example, silencing devices such as air conditioning ducts and fuel cell air intake pipes are also included.

[0015] Embodiments of the present invention will be described below with reference to Figures 1 to 13. Figure 1 is a perspective view showing an example of a sound-dampening device according to this embodiment, and Figure 13 is a schematic diagram of the sound-dampening device according to this embodiment.

[0016] The silencer 10 is connected to the internal combustion engine 20, which is a source of noise, and reduces the noise emitted along with the exhaust from the internal combustion engine 20. The internal combustion engine 20 is a so-called reciprocating engine that vaporizes gasoline or diesel fuel, mixes it with air in the cylinder and burns it, and outputs power by causing the piston to reciprocate due to the expansion during this combustion. The internal combustion engine 20 is installed in generators, construction machinery, vehicles, etc. Note that the source of noise is not limited to the internal combustion engine 20, but can be anything that emits noise and requires ventilation, such as air conditioners, boilers, fuel cells, etc.

[0017] The silencer 10 comprises a main pipe 1 connected to the internal combustion engine 20 as an exhaust pipe, and side branches (branch pipe units) 2 provided in the middle of the main pipe 1. In this embodiment, the silencer 10 is constructed using standardized parts for the main pipe 1 and side branches 2. Figure 2 shows an example of standardized parts. As shown in Figure 2, nine types of standardized parts are available for this embodiment: a tee pipe 51, a 45° elbow 52, ​​a 90° elbow 53, a 180° elbow 54, a short extension pipe 55, a long extension pipe 56, an intake side port (intake side part) 57, an exhaust side elbow 58, and an end cap 59. Note that the standardized parts in Figure 2 are just an example, and other types may be added or some types may be omitted. For example, it may include a straight pipe that does not extend or an elbow part bent with a different curvature than the elbow part described above.

[0018] Figure 3 shows the configuration of the air supply port 57. In Figure 3, (A) is a front view, (B) is a bottom view, and (C) is a top view. The air supply port 57 is a tubular part having openings at both ends, with a joint (connecting part) 571 at one end for connecting to a noise source and a joint 572 at the other end for connecting to other parts. In the example in Figure 3, the air supply port 57 is a straight pipe with joints 571 and 572 extending in one direction, but it is not limited to this and may be a curved pipe with the orientation of joint 571 (direction of the central axis) and joint 572 being different. A flange 573 is provided at the boundary between joint 571 and joint 572.

[0019] Figure 4 shows the configuration of the cheese tube 51. In Figure 4, (A) is a front view, (B) is a bottom view, (C) is a side view, and (D) is a top view. The cheese tube 51 comprises a main pipe section 511 having openings 51A and 51B at both ends, and a branch pipe section 512 that branches off from the main pipe section 511 and has an opening 51C at the end furthest from the main pipe section 511. The cheese tube 51 has joints 513, 514, and 515 at both ends of the main pipe section 511 and at the open ends of the branch pipe section, respectively, for connecting to other parts. Joint 513 is fitted onto the joint of another part (hereinafter also referred to as an external fitting joint), and when fitted onto the other joint, it is tightened. A screw hole 5131 for connecting is provided. That is, the opening 51A side end of the main pipe section 511 that is fitted onto another joint, and the screw hole 5131 constitute the fitting joint 513.

[0020] Joints 514 and 515 are small-diameter tubular members whose outer diameter is approximately the same as or slightly smaller than the inner diameter of the external fitting joint, and are inserted into the external fitting joint of other parts (hereinafter also referred to as internal fitting joints).

[0021] In Figure 4, the cheese pipe 51 is configured such that the axis of the branch pipe section 512 is perpendicular to the ventilation axis (hereinafter simply referred to as the axis) of the main pipe section 511. However, the configuration is not limited to this, and the main pipe section 511 and the branch pipe section 512 may branch at other angles. Also, in the example in Figure 4, the main pipe section 511 has openings 51A and 51B, and the branch pipe section 512 has an opening 51C, but the configuration is not limited to this. For example, the main pipe section 511 may have openings 51A and 51C, and the branch pipe section 512 may have an opening 51C. Alternatively, the main pipe section 511 may have openings 51B and 51C, and the branch pipe section 512 may have an opening 51A. In other words, the cheese pipe 51 may have one of the three branching ends designated as a branch pipe section 512, and the other end designated as a main pipe section 511. In other words, the cheese pipe 51 may be connected to one of its three branching ends to the upstream portion of the main pipeline 1, the downstream portion of the main pipeline 1 (main pipe unit 110), or the side branch 2.

[0022] Figure 5 shows the configuration of the 45° elbow 52. In Figure 5, (A) is a front view, (B) is a bottom view, and (C) is a side view. The 45° elbow 52 has an orientation (direction of the axis L) at one end that is 45° different from the orientation at the other end. The 45° elbow 52 also has joints 523 and 524 at both ends for connecting to other parts. Joint 523 is an external fitting joint that is fitted onto the joint of another part, and is provided with a screw hole 5231 for fastening the other joint in the fitted state. Joint 524 is an internal fitting joint that is inserted into the external fitting joint of another part.

[0023] Figure 6 shows the configuration of a 90° elbow 53, and Figure 7 shows the configuration of a 180° elbow 54. In Figures 6 and 7, (A) is a front view, (B) is a bottom view, and (C) is a side view. The 90° elbow 53 and 180° elbow 54 differ from the 45° elbow 52 in that the orientation of one end is different from the orientation of the other end, but the other configurations are the same. The 90° elbow 53 and 180° elbow 54 have external fitting joints 533 and 543 at one end for connecting to other parts, and internal fitting joints 534 and 544 at the other end for connecting to other parts. The external fitting joints 533 and 543 are external fitting joints that are fitted onto the joints of other parts, and are provided with screw holes 5331 and 5431 for fastening the other joints in the fitted state. In this embodiment, the 45° elbow 52, ​​90° elbow 53, and 180° elbow 54 are forms of elbow parts. However, the elbow parts are not limited to these and may be parts bent at other angles.

[0024] Figure 8 shows the configuration of the short expansion joint 55. In Figure 8, (A) is a front view, (B) is a left side view, and (C) is a right side view. The short expansion joint 55 has an expansion mechanism that expands and contracts its length in the axial direction (ventilation direction). In this embodiment, the expansion mechanism of the short expansion joint 55 is a telescopic structure having an inner cylinder 551 and an outer cylinder 552 that fits over the inner cylinder 551. Flange portions 5551 and 5552 are provided on the outer circumferential surfaces of the inner cylinder 551 and the outer cylinder 552 so as to protrude radially outward (axial direction), and the flange portion 5551 of the inner cylinder 551 and the flange portion 5552 of the outer cylinder 552 are connected by a connecting member 550. The connecting member 550 has a threaded rod 557 and a nut 558. The flange portions 5551 and 5552 are formed such that the outer shape when viewed in the axial direction of the inner cylinder 551 and the outer cylinder 552 is generally triangular. Furthermore, the flange portions 5551 and 5552 are provided with grooves 556 extending from each vertex of the triangle toward the axis.

[0025] The short expansion joint 55 is fixed relative to the inner cylinder 551 and the outer cylinder 552 by inserting the threaded rod 557 of the connecting member 550 through the groove 556 of the flange portion 5551 of the inner cylinder 551 and the groove 556 of the flange portion 5552 of the outer cylinder 552, and clamping the flange portions 5551 and 5552, respectively, with multiple nuts 558 screwed onto the threaded rod 557. At this time, the short expansion joint 55 can be extended or retracted by changing the distance between the flange portions 5551 and 5552. That is, if the length of the part of the inner cylinder 551 that is not inserted into the outer cylinder 552 is short and the length of the part inserted into the outer cylinder 552 is long, the axial length of the entire short expansion joint 55 (hereinafter also referred to as the total length) will be shortened. On the other hand, if the length of the part of the inner cylinder 551 that is inserted into the outer cylinder 552 is short, the total length of the short expansion joint 55 will be lengthened. The telescopic mechanism may also have other configurations, such as a bellows type. For example, a female threaded portion may be provided on the inner circumferential surface of the outer cylinder 552, and a male threaded portion may be provided on the outer circumferential surface of the inner cylinder 551, so that the outer cylinder 552 and the inner cylinder 551 are screwed together, the short telescopic tube 55 is retracted by screwing the inner cylinder 551 into the outer cylinder 552, and the short telescopic tube 55 is extended by rotating the inner cylinder 551 in the opposite direction to the screwing direction (hereinafter also referred to as a screw structure). Alternatively, the telescopic mechanism may have a structure using a bellows-shaped tube, an accordion-shaped tube, a flexible tube, or other expandable tube.

[0026] The short expansion joint 55 has a joint 553 on the outer cylinder 552, opposite to the end connected to the inner cylinder 551, for connecting to other parts. The joint 553 is an external fitting joint that fits onto the joint of another part, and is provided with a screw hole 5531 for fastening the other joint while it is fitted onto the outer part. The short expansion joint 55 also has a joint 554 on the inner cylinder 551, opposite to the end connected to the outer cylinder 552, for connecting to other parts. The joint 554 is an internal fitting joint that is inserted into the joint of another part.

[0027] Figure 9 shows the configuration of the long expansion joint 56. In Figure 8, (A) is a front view, (B) is a left side view, and (C) is a right side view. The long expansion joint 56 differs from the short expansion joint 55 in that it has a longer length in the axial direction (ventilation direction), but the other configurations are the same. The inner cylinder 561, outer cylinder 562, flange parts 5651, 5652, connecting member 560, groove 566, threaded rod 567, nut 568, and joints 563, 564 of the long expansion joint 56 correspond to the inner cylinder 551, outer cylinder 552, flange parts 5551, 5552, connecting member 550, groove 556, threaded rod 557, nut 558, and joints 553, 554 of the short expansion joint 55, and have similar functions, so a further explanation is omitted. Furthermore, the long telescopic tube 56, like the short telescopic tube 55, may have a telescopic mechanism of other configurations, such as a bellows type or a screw structure.

[0028] Figure 10 shows the configuration of the exhaust elbow 58. In Figure 10, (A) is a front view, (B) is a bottom view, and (C) is a side view. The exhaust elbow 58 has one end 581 oriented (direction of the axis L) which is 90° different from the orientation of the other end 582. The exhaust elbow 58 also has a joint 583 at one end 581 for connecting to other parts. The joint 583 is an external fitting joint that fits onto the joint of the other part. The other end 582 of the exhaust elbow 58 does not have a joint and is simply an opening (exhaust port).

[0029] Figure 11 shows the configuration of the end cap (closing member) 59. In Figure 11, (A) is a front view, (B) is a bottom view, and (C) is a top view. The end cap 59 includes a joint 593 for connecting to other parts and a closing plate 595 for closing the internal space (exhaust path) of the connected parts. The end cap 59 is connected to a joint located on the closing end side of a part that is positioned on the end (closing end) side furthest from the cheese pipe 51 in the side branch 2, and closes the opening on the closing end side of that part.

[0030] Each of the parts 51-59 is a standardized part, differing in length, inner diameter, and joint shape. The shape and other specifications are defined. For example, the 45° elbow 52, ​​90° elbow 53, 180° elbow 54, supply port 57, and exhaust elbow 58 have a specified length along the axis from the opening at one end to the opening at the other end in the internal space (exhaust path) (hereinafter also referred to as the path length). The tee pipe 51 has specified path lengths in the main pipe section 511 and the branch pipe section 512. The short extension pipe 55 is shorter than the long extension pipe 56, and in this embodiment, its path length can be extended from 200 to 300 mm. The long extension pipe 56 has a path length that can be extended from 400 to 700 mm.

[0031] The external fitting joints 513, 523, 533, 543, 553, 563, 583, and 593 in the tee tube 51, 45° elbow 52, ​​90° elbow 53, 180° elbow 54, short expansion joint 55, long expansion joint 56, exhaust side elbow 58, and end cap 59 are all identical in shape. In addition, the internal fitting joints 514, 515, 524, 534, 544, 554, 564, and 574 in the tee tube 51, 45° elbow 52, ​​90° elbow 53, 180° elbow 54, short expansion joint 55, long expansion joint 56, and supply side port 57 are all identical in shape. As a result, each part 51-59 can be arbitrarily connected by fitting the external joints 513, 523, 533, 543, 553, 563, 583, and 593 onto the internal joints 514, 515, 524, 534, 544, 554, 564, and 574. In other words, each standardized part has at least one standardized joint (external joint and internal joint) and can be combined with other standardized parts.

[0032] The silencing device 10 of this embodiment is constructed by combining the parts 51 to 59 described above. In the example shown in Figure 1, the joint 571 at one end of the intake port 57 is connected to the exhaust port 201 of the internal combustion engine 20, and the external fitting joint 533 of the 90° elbow 53 is fitted onto the internal fitting joint 572 at the other end.

[0033] An external fitting joint 553 of a short expansion joint 55 is fitted onto the internal fitting joint 534 of the 90° elbow 53, and an external fitting joint 513 of a cheese tube 51 is fitted onto the internal fitting joint 554 of the short expansion joint 55.

[0034] An external fitting joint 563 of a long extension pipe 56 is fitted onto an internal fitting joint 514 provided at the exhaust end of the cheese pipe 51, and an external fitting joint 563 of another long extension pipe 56 is fitted onto an internal fitting joint 564 of the long extension pipe 56. In other words, two long extension pipes 56 are connected. Of these, an external fitting joint 583 of an exhaust side elbow 58 is fitted onto the internal fitting joint 564 of the long extension pipe 56 located on the exhaust side.

[0035] Furthermore, the internal joint 515 of the cheese tube 51 is fitted with the external joint 563 of the long expansion tube 56, and the internal joint 564 of the long expansion tube (first expansion part) 56 is fitted with the external joint 543 of the 180° elbow 54. The internal joint 544 of the 180° elbow 54 is fitted with the external joint 563 of the long expansion tube (second expansion part) 56, and the internal joint 564 of the long expansion tube 56 is fitted with the external joint 593 of the end cap 59.

[0036] Screws are screwed into the screw holes 5131, 5231, 5331, 543, 553, 563, 583, and 5931 in the external fitting joints 513, 523, 533, 543, 553, 563, 583, and 5931 of each part 51 to 59, and the tips of these screws tighten the internal fitting joints 514, 515, 524, 534, 544, 554, 564, and 574 from the outside, thereby fastening each part 51 to 59 together.

[0037] In the example shown in Figure 1, the long extension pipe 56 and the exhaust elbow 58 constitute the main pipe unit 110, and this main pipe unit 110, along with the supply port 57, the 90° elbow 53, the short extension pipe 55, and the tee, are also part of the main pipe unit 110. The main section 511 of pipe 51 constitutes the main pipeline 1. The branch section 512 of the tee pipe 51, the two long extension pipes 56, the 180° elbow 54, and the end cap 59 constitute the side branch 2. The silencer 10 is fixed by a fastener 61. Figure 12 shows the configuration of the fastener 61. The fastener 61 has a band section 611 formed in a semi-circular shape along the outer circumference of the pipe, tightening sections 612 extending radially outward from both ends of the band section, a base section 614 attached to the object to be attached (internal combustion engine 20), a threaded rod 613 erected on the base section 614, and a nut 6121 that screws onto the threaded rod 613. The fastener 61 consists of a pair of band sections 611 arranged to surround the tubular portion (e.g., the external joint) of the silencer 10, with clamping sections 612 located at both ends of these band sections 611, positioned opposite each other with a slight gap between them. Through holes are provided in the opposing clamping sections 612, through which a threaded rod 613 is passed. The pair of clamping sections 612 are then tightened together by nuts 6121, bringing them closer together, so that the band sections 611 clamp the tubular portion of the silencer 10. The base section 614, on which the threaded rod 613 is provided, is then attached to the outer plate of the internal combustion engine 20 with screws or the like. Note that the attachment of the base section 614 is not limited to screws; it may also be attached by forming grooves in the outer plate and fitting it in, welding, adhesive, magnetic attachment, or a combination of these methods.

[0038] Figure 13 is a schematic diagram of the silencer 10. In Figure 13, for the sake of explanation, the main pipe 1 and side branch 2 are shown in a linear configuration. The main pipe 1 has openings at both ends, with one opening designated as the first opening 11 and the other as the second opening 12. The first opening 11 is the opening closest to the air supply at the air supply port 57 in Figure 1, and the second opening 12 is the opening closest to the exhaust (boundary with the outside) at the exhaust elbow 58. The side branch 2 is a tubular silencer that communicates with the main pipe 1 at the branching section (branching part) end 21 and has the other end 22 closed. The branching section end 21 is the end located at the boundary between the branch section (Figure 4) 512 of the branching part (tee pipe) and the main pipe section 511, and the other end 22 is the end (closed end) where the closing plate 595 of the end cap 59 is located. The inner diameter of the main pipeline 1 and the inner diameter of the side branch 2 are approximately the same.

[0039] The point where the longitudinal axis of the interior of side branch 2 intersects with the longitudinal axis of the interior of main pipeline 1 is defined as branching point 23. In the direction of noise passage from the first opening 11 to the second opening 12 of main pipeline 1, the section from the first opening 11 to branching point 23, which is on the upstream side, is defined as the upstream main pipeline 14, and the section from branching point 23 to the second opening 12 is defined as the downstream main pipeline 15.

[0040] Of the noise emitted from the internal combustion engine 20, low-frequency noise that is difficult to reduce with soundproofing sheets, etc., appears as sound waves with periods based on the combustion timing of each cylinder, etc. Therefore, the side branch 2 is designed to reduce this low-frequency noise. When the wavelength of the frequency to be reduced is λ, the length L3 of the side branch 2 from the connection point with the main pipe 1 (branching point 23) to the inner wall surface of the closed end 22 is set to λ / 4.

[0041] Assuming the length of side branch 2 is λ / 4, the sound waves of wavelength λ emitted from the internal combustion engine 20 travel through the upstream main pipeline 14, branch into side branch 2 at branching point 23, reflect at the closed end 22, and return to branching point 23. At this point, the phase of the sound waves is shifted by λ / 2 compared to the sound waves traveling from branching point 23 to the downstream main pipeline 15. Therefore, the sound pressure is reduced due to interference between the sound waves returning from side branch 2 and the sound waves traveling to the downstream main pipeline 15.

[0042] Furthermore, by setting the length L1 from the first opening 11 of the main pipeline 1 to the junction of the side branch 2 (length of the upstream main pipeline 14) and the length L2 from the second opening of the main pipeline 1 to the junction of the side branch 2 (length of the downstream main pipeline 15) to (2n+1)λ / 4 (where n is a natural number including 0), noise reduction can be effectively achieved. Note that the length L1 may include the length of the pipeline installed inside the internal combustion engine 20 in addition to the length of the upstream main pipeline 14. For example, from the exhaust side opening of the engine in the internal combustion engine 20 to the intake side port 57 The length to the exhaust port may be added to the length of the upstream main pipe 14 and defined as length L1.

[0043] As described above, the wavelength λ used to determine the length of the sound-dampening device 10 is determined, for example, as shown in Equation 1. Wavelength λ(m) = Sound speed (m / s) ÷ Frequency (Hz) (Formula 1)

[0044] When the speed of sound in air is assumed to be 340 m / s, the relationship between the wavelength λ to be reduced and λ / 4 is as follows: The results are as shown in the following table.

[0045] [Table 1]

[0046] Furthermore, if the internal combustion engine 20 is a reciprocating compressor or a reciprocating engine, the dominant frequency f (Hz) of the exhaust noise can be calculated as shown in Equation 2, and this can also be used as the frequency to be reduced.

[0047] f=Rm / 60K (Formula 2) Here, R, m, and K are as follows: R: Engine rotation speed (rpm) m: Number of cylinders (m=1,2,3…) K: Cycle constant (K=2 for 4 cycles, K=1 for 2 cycles)

[0048] For example, if the rated rotational speed R of the internal combustion engine 20 is 2000 rpm, the number of cylinders m is 4, and the cycle constant K is 2, then the dominant frequency f will be 66.7 Hz as shown in the following equation. f = 2000 × 4 / 60 / 2 = 66.7 (Hz)

[0049] Furthermore, when determining the lengths of the main pipe 1 and side branch 2, the speed of sound may be changed according to the exhaust temperature. For example, if the speed of sound at 0°C is 331.5 m / s, then the temperature t (°C) can be added. The speed of sound c (m / s) is given by c = 331.5(1+t / 273)^(1 / 2). Applying this to Equation 1, the wavelength λ (m) taking temperature into account can be obtained as shown in Equation 3. λ=331.5 ( 1+t / 273 )^(1 / 2) / f... (Equation 3)

[0050] For example, if the frequency f is 66.7 (Hz), the relationship between temperature t (°C) and λ / 4 is as shown in the following table. Yes.

[0051] [Table 2]

[0052] As the speed of sound changes with temperature, the λ / 4 suitable for noise reduction at the target frequency also changes. Therefore, the main pipe 1 and side branch 2 may be designed with lengths that take into account the exhaust temperature of the internal combustion engine 20 based on Equation 3. This allows for appropriate reduction of the target noise. The exhaust temperature is measured, for example, by placing a temperature sensor at the branching point 23. However, the exhaust temperature may also be measured at the engine's exhaust port, the first opening 11 in the main pipe 1, inside the side branch 2, or the second opening 12 in the main pipe 1. In this case, a coefficient may be applied so that the measured value corresponds to the value measured at the branching point 23. Furthermore, the lengths of the main pipe 1 and side branch 2 may be determined by taking into account other factors such as exhaust velocity, humidity, and pressure, not just temperature.

[0053] <Effects of the Embodiment> (1) As described above, the ideal length of the main pipe 1 and side branch 2 is determined by the dominant frequency of the noise source, temperature, exhaust flow velocity, etc. Therefore, it is desirable to attach the silencer 10 designed for these values ​​to the internal combustion engine 20. However, in reality, it may not be possible to attach it to the designed position due to interference with structures (obstacles) such as maintenance hatches or the driver's cab of heavy machinery. Even in this case, the silencer 10 of this embodiment can be modified by rearranging parts to change its shape and enable attachment while avoiding interference with other structures. For example, by adding elbows 52 to 54 to change the direction of the piping, and by shortening the expansion joints 55 and 56 by the amount extended by this addition, it is possible to avoid obstacles while maintaining the appropriate length of the main pipe 1 and side branch 2.

[0054] (2) The sound-dampening device 10 of this embodiment provides multiple types of elbow parts with different angles between one end and the other, such as a 45° elbow 52, ​​a 90° elbow 53, and a 180° elbow 54. This allows the sound-dampening device 10 of this embodiment to flexibly change the direction of the piping according to the site conditions and avoid interference with obstacles.

[0055] (3) In this embodiment, the sound-dampening device 10 has a side branch (branch pipe unit) 2 equipped with telescopic pipes (telescopic parts) 55 and 56, and when the wavelength of noise generated from the noise source is λ, the length of the side branch 2 is made λ / 4 by the telescopic pipes (telescopic parts) 55 and 56. As a result, the sound-dampening device 10 in this embodiment can effectively dampen noise of a predetermined frequency, such as the dominant frequency of a reciprocating engine.

[0056] (4) The silencer 10 of this embodiment includes a side branch 2 comprising a 180° elbow 54 in which the orientation of one end differs by 180 degrees from the orientation of the other end, expansion joints (first expansion joint parts) 55, 56 positioned on the intake side of the 180° elbow 54, and expansion joints (second expansion joint parts) 55, 56 positioned on the exhaust side of the said expansion joints 55, 56. Furthermore, the silencer 10 is internal combustion When the wavelength of the noise generated from the engine 20 is λ, the length of the side branch 2 is made λ / 4 by the first and second telescopic parts. This allows the silencer 10 of this embodiment to have a compact side branch 2.

[0057] (5) The sound-dampening device 10 of this embodiment has a telescopic structure in which the telescopic mechanism of the telescopic tubes (telescopic parts) 55 and 56 has an inner cylinder 551, 561 and an outer cylinder 552, 562 that fits over the inner cylinder 551, 561. This makes it possible to extend and retract the exhaust path with a simple configuration.

[0058] (6) The sound-dampening device 10 of this embodiment further comprises an extension mechanism for the telescopic tubes (extension parts) 55 and 56, which includes flange portions 5551 and 5651 provided on the inner cylinders 551 and 561, flange portions 5552 and 5652 provided on the outer cylinders 552 and 562, and connecting members 550 and 560 that connect the flange portions 5551 and 5651 of the inner cylinders 551 and 561 with the flange portions 5552 and 5652 of the outer cylinders 552 and 562. The outer shape of these flange portions 5551, 5651, 5552 and 5652 is triangular when viewed in the axial direction of the inner cylinders 551 and 561 and the outer cylinders 552 and 562. As a result, in the sound-dampening device 10 of this embodiment, when the telescopic tubes 55 and 56 are arranged in parallel as shown in Figure 1, even if the distance between the telescopic tubes 55 and 56 is narrowed by arranging the flange portions 5551, 5651, 5552, and 5652 of adjacent telescopic tubes 55 and 56 in reverse, these flange portions 5551, 5651, 5552, and 5652 do not interfere with each other, and the sound-dampening device 10 can be made compact.

[0059] The configurations and combinations thereof in the embodiments described above are examples, and additions, omissions, substitutions, and other modifications are possible as appropriate, without departing from the spirit of this disclosure. This disclosure is not limited by the embodiments, but is limited only by the claims. Furthermore, each aspect disclosed herein can be combined with any other features disclosed herein. [Explanation of Symbols]

[0060] 1: Main pipe 2: Side branch (branch pipe unit) 10: Silencer 11: First opening 12: Second opening 14: Upstream main pipeline 15: Downstream main pipeline 20: Internal combustion engine 51: Cheese tube 52:45° Elbow 53:90° Elbow 54: 180° Elbow 55: Short telescopic tube 56: Long telescopic tube 57: Air intake port 58: Exhaust side elbow 59: End cap 61: Fixtures 110: Main Unit 201: Exhaust port 511: Main department 512: Branch pipe section 513, 523, 533, 543, 553, 563, 583, 593: External fitting joint 514, 515, 524, 534, 544, 554, 564, 574: Interpolation joints 5131, 5231, 5331, 5431, 5531, 5631, 5831, 5931: Screw holes

Claims

1. A tubular part having openings at both ends, an air supply side part having a joint at one end for connecting to a noise source and a joint at the other end for connecting to another part, A branch part comprising a main pipe section having openings at both ends, and a branch pipe section branching from the main pipe section and having an opening at the end furthest from the main pipe section, with joints at both ends of the main pipe section and the open end of the branch pipe section for connecting to other parts, A main pipe unit comprising at least one tubular part, the tubular part having a joint at one end for connecting to the joint at the exhaust end of the branch part, A branch pipe unit having at least one tubular part, wherein a joint for connecting to the joint of the branch part is provided at the end of the tubular part on the branch part side, and a closing member is provided at the other end, Equipped with, The joints in the air supply side part, the branch part, the tubular part included in the main pipe unit, and the tubular part included in the branch pipe unit are detachable from each other. At least one of the tubular parts included in the main pipe unit and the tubular parts included in the branch pipe unit is an expandable / contractable part equipped with an expandable / contractable mechanism for extending or retracting the length of the pipe. Silencer.

2. The sound-dampening device according to claim 1, further comprising an elbow part having openings at both ends, wherein the orientation of the other end differs from that of one end.

3. The branch pipe unit includes the telescopic part, When the wavelength of the noise generated from the noise source is λ, the length of the branch pipe unit is made λ / 4 by the telescopic part. The sound-dampening device according to claim 1.

4. The aforementioned branch pipe unit, An elbow part in which the orientation of one end is 180 degrees different from the orientation of the other end, A first telescopic part positioned on the branching part side of the elbow part, A second expandable part is positioned on the closing member side of the elbow part, Equipped with, When the wavelength of the noise generated from the noise source is λ, the length of the branch pipe unit is made λ / 4 by the first telescopic part and the second telescopic part. The sound-dampening device according to claim 1.

5. The sound-dampening device according to any one of claims 1 to 4, wherein the telescopic mechanism of the telescopic part comprises an inner cylinder and an outer cylinder fitted onto the inner cylinder, and has a telescopic structure, a screw structure in which the inner cylinder and the outer cylinder are screwed together, or a structure using a bellows-shaped tube.

6. The telescopic mechanism of the aforementioned telescopic part is A flange portion provided on the inner cylinder, The flange portion provided on the outer cylinder, A connecting portion that connects the flange portion of the inner cylinder and the flange portion of the outer cylinder, Furthermore, The sound-dampening device according to claim 5, wherein the flange portion of the inner cylinder and the flange portion of the outer cylinder have a triangular shape when viewed in the axial direction of the inner cylinder and the outer cylinder.

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