Aftertreatment noise elimination structure of gas machine

Abstract

The utility model provides a gas machine post-treatment noise elimination structure, which comprises a post-treatment part and a noise elimination part, the noise elimination part comprises a bent pipe, an exhaust pipe, an exhaust pipe and an exhaust pipe, one end of the high-frequency pipe is connected to the other end of the bent pipe, and a plurality of fine holes are uniformly distributed in the middle section of the high-frequency pipe; the first barrel and the high-frequency tube are coaxially arranged, the two ends of the first barrel are closed, so that a resonant cavity is formed between the first barrel and the high-frequency tube, and the middle section of the high-frequency tube is hidden in the resonant cavity; the resonant tube is located in the resonant cavity, and one end of the resonant tube is connected with the surface of the high-frequency tube; the silencing cotton wraps the middle section of the high-frequency pipe and covers the fine holes; a Helmholtz resonant cavity structure is additionally arranged, so that the low and medium frequency noise elimination amount is increased; a high-frequency tube is added to suppress high-frequency noise.

Description

Technical Field

[0001] The utility model relates to a commercial automobile accessory, in particular to a gas engine post-processing silencer structure. Background Art

[0002] With the rapid development of new energy technologies, commercial vehicle engines are evolving from traditional diesel engines to a variety of new clean fuel engines, such as methanol and natural gas. These engines can reduce harmful emissions while also delivering excellent economic benefits. However, compared to traditional diesel engines, gas engines have significantly higher exhaust flow rates, placing higher demands on noise control in exhaust aftertreatment systems.

[0003] With post-processor silencing systems, every OEM currently targets volume reduction and cost reduction. Therefore, achieving optimal silencing within limited constraints requires continuous research and exploration by our technical staff. Small post-processors, due to their limited silencing capacity, are difficult to control low-frequency order noise, resulting in poor silencing effectiveness. Summary of the Invention

[0004] In response to the shortcomings of the existing technology, the utility model provides a gas engine post-processing silencer structure, which adds a Helmholtz resonance cavity structure to improve the low- and medium-frequency silencer; and adds a high-frequency tube to suppress high-frequency noise. The technical solution adopted by the utility model is:

[0005] A gas engine post-processing silencer structure comprises a post-processing unit and a silencer unit, wherein the silencer unit comprises:

[0006] an elbow, one end of which is connected to the downstream end of the post-processing section;

[0007] A high-frequency tube, one end of which is connected to the other end of the bent tube, and a middle section of the high-frequency tube is evenly distributed with a plurality of fine holes;

[0008] a first cylinder coaxially arranged with the high-frequency tube, with both ends of the first cylinder closed so that a resonance cavity is formed between the first cylinder and the high-frequency tube, and a middle section of the high-frequency tube is hidden in the resonance cavity;

[0009] A resonance tube, located in the resonance cavity, one end of which is connected to the surface of the high-frequency tube;

[0010] The sound-absorbing cotton is wrapped around the middle section of the high-frequency tube and covers the fine holes.

[0011] Furthermore, the post-processing unit includes:

[0012] a second cylinder, wherein a catalyst assembly is disposed inside the second cylinder;

[0013] an air inlet pipe, one end of which is connected to the upstream end of the second cylinder;

[0014] The air outlet pipe is arranged at the downstream end of the second cylinder and connected to one end of the elbow.

[0015] Furthermore, the catalyst assembly includes a first catalyst carrier, a second catalyst carrier and a third catalyst carrier sequentially arranged in the second cylinder along the axis of the second cylinder.

[0016] Furthermore, the air outlet pipe is arranged inside the second cylinder, and one end thereof extends to the side of the second cylinder. A plurality of air outlet holes are evenly arranged on the side of the air outlet pipe facing the third catalyst carrier.

[0017] Furthermore, the axis of the air outlet pipe is perpendicular to the axis of the second cylinder.

[0018] Furthermore, a blocking piece is provided at one end of the air outlet pipe away from the bent pipe.

[0019] Furthermore, the second cylinder is arranged parallel to the first cylinder.

[0020] Furthermore, the first cylinder is connected to the second cylinder through a first bracket.

[0021] Furthermore, the surface of the second cylinder is detachably connected to a second bracket via a clamp.

[0022] Advantages of this utility model:

[0023] The resonance cavity added at the tail of the post-processing unit is a Helmholtz resonance cavity, which takes up little space and can effectively solve the problem of insufficient low-frequency noise reduction performance in small-volume mufflers to a certain extent;

[0024] The high-frequency tube, silencer cotton and Helmholtz resonance cavity structure are combined to improve the mid- and low-frequency sound absorption while suppressing high-frequency noise;

[0025] Effectively utilize the space occupied by the catalyst carrier, and set the outlet holes on the outlet pipe to ensure the uniformity of air flow while improving the low-frequency noise reduction capability;

[0026] A baffle is set at the end of the outlet pipe to ensure that most of the air flows through the outlet hole;

[0027] The silencer structure takes up little space and can effectively reduce the volume of the muffler. It is very suitable for models with limited body boundaries. The muffler is compactly designed, has almost no excess performance, and is highly economical. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the structural composition of the present utility model.

[0029] Figure 2 It is a cross-sectional view of the present utility model.

[0030] Figure 3 This is the low-frequency transmission loss curve of the utility model.

[0031] Figure 4 This is a comparison chart of the third-order noise optimization effect of the utility model.

[0032] In the figure: 1-bend pipe, 2-high frequency tube, 3-first cylinder, 4-resonance tube, 5-silence cotton, 6-second cylinder, 7-inlet pipe, 8-outlet pipe, 9-first catalyst carrier, 10-second catalyst carrier, 11-third catalyst carrier, 12-first bracket, 13-second bracket. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0034] Please see the attached Figure 1 and attached Figure 2 The utility model provides a gas engine post-processing silencer structure, including a post-processing part and a silencer part, the silencer part including: a bent pipe 1, one end of which is connected to the downstream end of the post-processing part; a high-frequency tube 2, one end of which is connected to the other end of the bent pipe 1, and a plurality of fine holes are evenly distributed in the middle section of the high-frequency tube 2; a first cylinder 3, which is coaxially arranged with the high-frequency tube 2, and both ends of the first cylinder 3 are closed, so that a resonance cavity is formed between the first cylinder 3 and the high-frequency tube 2, and the middle section of the high-frequency tube 2 is hidden in the resonance cavity; a resonance tube 4, which is located in the resonance cavity and one end of which is connected to the surface of the high-frequency tube 2; and silencer cotton 5, which is coated on the middle section of the high-frequency tube 2 and covers the fine holes.

[0035] Existing gas engine after-treatment silencer structures are typically square boxes with volumes up to 100L, with space inside for the relevant silencer components. Due to their large volume and high expansion ratio, they are generally less susceptible to low-frequency noise issues. However, when the after-treatment silencer structure has a volume of only 50-60L, and most of the space is occupied by the carrier, the silencer space is extremely limited, making many optimization solutions impossible to implement.

[0036] Based on this, the utility model optimizes the combined structure of the post-processing part and the silencer part. The resonance cavity formed between the high-frequency tube 2 and the first cylinder 3 can be regarded as a Helmholtz resonance cavity. After the exhaust passes through the post-processing part, it enters the resonance cavity and cooperates with the resonance tube 4 to achieve silencer of medium and low frequency noise. At the same time, the high-frequency tube 2 and the silencer cotton 5 take into account the control of high-frequency fluid noise, solving the problem of poor silencer effect of medium and low frequency noise in the current small-capacity post-processing silencer structure.

[0037] In one embodiment, the pore diameter is selected to be 3 mm to 5 mm, and the number of pores is adjusted according to the sound-absorbing capacity and back pressure without any specific restrictions. The sound-absorbing cotton 5 covers all the pores to ensure the effect of eliminating high-frequency noise.

[0038] In one embodiment, both ends of the first cylinder 3 are configured as cover plates, and the cover plates are fixed to the high-frequency tube 2 by welding to ensure the sealing of the resonance cavity.

[0039] In one embodiment, the diameter and length of the resonance tube 4 can be calculated by the Helmholtz resonance cavity frequency formula QUOTE The noise frequency that needs to be adjusted is determined by is the resonance cavity frequency, c is the sound propagation velocity, A is the cross-sectional area of ​​the resonance tube 4, V is the cavity volume, and L is the length of the resonance tube 4. The frequency adjusted by the resonance cavity is determined according to the actual performance of the engine in the vehicle. The frequency adjusted is generally low-frequency noise. The parameters adjusted are the actual volume of the resonance cavity, the diameter of the resonance tube 4, and the length of the resonance tube 4. By selecting a suitable resonance tube 4, the low-frequency transmission loss of the silencer structure of the utility model and the existing silencer structure is compared. Figure 3 As shown in the attached figure, the third-order noise test comparison between the noise elimination structure of the utility model and the existing noise elimination structure is shown in the attached figure. Figure 4 As shown, it can be seen that the utility model improves the silencing effect of medium and low frequency noise while taking into account the suppression of high frequency noise.

[0040] As an embodiment of the present application, the cross section of the resonance tube 4 may be circular, rectangular or the like.

[0041] In this application, as attached Figure 1 and attached Figure 2 As shown, the post-processing part includes: a second cylinder 6, a catalyst assembly is arranged inside the second cylinder 6; an air inlet pipe 7, one end of which is connected to the upstream end of the second cylinder 6; and an air outlet pipe 8, which is arranged at the downstream end of the second cylinder 6 and connected to one end of the elbow 1.

[0042] Specifically, the intake pipe 7 is arranged on the side of the second cylinder 6 and is staggered with the first cylinder 3, that is, the intake pipe 7 does not affect the installation of the first cylinder 3, nor does it interfere with it; the exhaust gas enters the second cylinder 6 from the intake pipe 7, is processed by the catalyst assembly, and is discharged from the outlet pipe 8.

[0043] In one specific embodiment, the catalyst assembly includes a first catalyst carrier 9, a second catalyst carrier 10, and a third catalyst carrier 11, which are sequentially arranged within the second cylinder 6 along the axis of the second cylinder 6. The first catalyst carrier 9, the second catalyst carrier 10, and the third catalyst carrier 11 are each fixed to the inner wall of the second cylinder 6 using a welded base. The first catalyst carrier 9, the second catalyst carrier 10, and the third catalyst carrier 11 are each loaded with the required catalyst to meet the exhaust post-treatment requirements.

[0044] In one embodiment, to compact the post-processing unit's spatial structure, the outlet pipe 8 is positioned within the second cylindrical body 6, with one end extending to the side of the second cylindrical body 6. The outlet pipe 8 has a number of outlet holes evenly spaced on the side facing the third catalyst carrier 11. The diameter and number of the outlet holes are adjusted based on back pressure to improve exhaust gas flow uniformity. Specifically, after passing through the catalyst assembly, the majority of the exhaust gas enters the outlet pipe 8 through the outlet holes and then flows into the elbow 1, thereby improving exhaust gas flow uniformity.

[0045] To achieve turbulent flow reversal within the exhaust gas outlet pipe 8, the axis of the outlet pipe 8 is perpendicular to the axis of the second cylinder 6. Exhaust gas enters the outlet pipe 8 radially from the outlet port, undergoes a 90-degree reversal, and then exits the outlet pipe 8 axially, entering the elbow 1. This makes the post-processing unit more compact, with virtually no excess performance, and reduces its overall volume.

[0046] To allow most of the exhaust to enter the outlet pipe 8 through the outlet hole, a baffle is provided at the end of the outlet pipe 8 away from the elbow 1. The baffle can be configured to completely block the end of the outlet pipe 8 or partially block the end of the outlet pipe 8 according to the back pressure; a hole can also be made in the baffle.

[0047] To further streamline the modularization of the post-processing muffler structure, the second cylinder 6 is arranged parallel to the first cylinder 3. After the exhaust pipe 8 turns 90 degrees, the exhaust passes through the elbow 1 and then turns 90 degrees, extending the exhaust flow path while saving the volume of the post-processing muffler structure.

[0048] In order to facilitate the connection and fixation between the first cylinder 3 and the second cylinder 6 , the first cylinder 3 is connected to the second cylinder 6 via a first bracket 12 .

[0049] In order to facilitate the installation of the second cylinder 6 in the vehicle, a second bracket 13 is detachably connected to the surface of the second cylinder 6 via a clamp.

[0050] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solution of the utility model and are not limiting. Although the utility model is described in detail with reference to examples, ordinary technicians in this field should understand that the technical solution of the utility model can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the utility model, which should be included in the scope of the claims of the utility model.

Claims

1. A gas engine post-processing silencer structure, characterized in that: It includes a post-processing unit and a muffler unit, and the muffler unit includes: An elbow (1), one end of which is connected to the downstream end of the post-processing section; A high-frequency tube (2), one end of which is connected to the other end of the bent tube (1), and a middle section of the high-frequency tube (2) is evenly distributed with a plurality of fine holes; A first cylinder (3) is coaxially arranged with the high-frequency tube (2), with both ends of the first cylinder (3) being closed, so that a resonance cavity is formed between the first cylinder (3) and the high-frequency tube (2), and a middle section of the high-frequency tube (2) is hidden in the resonance cavity; A resonance tube (4) is located in the resonance cavity, one end of which is connected to the surface of the high-frequency tube (2); The sound-absorbing cotton (5) is wrapped around the middle section of the high-frequency tube (2) and covers the fine holes.

2. The gas engine post-processing silencer structure according to claim 1, characterized in that: The post-processing unit includes: A second cylinder (6), wherein a catalyst assembly is provided inside the second cylinder (6); an air inlet pipe (7), one end of which is connected to the upstream end of the second cylinder (6); An air outlet pipe (8) is provided at the downstream end of the second cylinder (6) and is connected to one end of the elbow (1).

3. The gas engine post-processing noise reduction structure according to claim 2, characterized in that: The catalyst assembly comprises a first catalyst carrier (9), a second catalyst carrier (10) and a third catalyst carrier (11) which are sequentially arranged in the second cylinder (6) along the axis of the second cylinder (6).

4. The gas engine post-processing noise reduction structure according to claim 3, characterized in that: The air outlet pipe (8) is arranged inside the second cylinder (6), with one end thereof extending to the side of the second cylinder (6). The air outlet pipe (8) is evenly arranged with a plurality of air outlet holes on the side facing the third catalyst carrier (11).

5. The gas engine post-processing noise reduction structure according to claim 4, characterized in that: The axis of the air outlet pipe (8) is perpendicular to the axis of the second cylinder (6).

6. The gas engine post-processing noise reduction structure according to claim 5, characterized in that: A baffle is provided at one end of the air outlet pipe (8) away from the bent pipe (1).

7. The gas engine post-processing noise reduction structure according to any one of claims 2 to 6, characterized in that: The second cylinder (6) is arranged parallel to the first cylinder (3).

8. The gas engine post-processing noise reduction structure according to claim 7, characterized in that: The first cylinder (3) is connected to the second cylinder (6) via a first bracket (12).

9. The gas engine post-processing noise reduction structure according to any one of claims 2 to 6, characterized in that: The surface of the second cylinder (6) is detachably connected to a second bracket (13) via a clamp.

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