Noise elimination structure for eliminating low-frequency roar of engine and reducing high-rotating-speed exhaust back pressure

Abstract

The utility model discloses a noise elimination structure for eliminating low-frequency roar of an engine and reducing high-rotating-speed exhaust back pressure, which comprises a noise elimination shell, an air inlet is arranged at the front end of the noise elimination shell, an air outlet is arranged at the rear end of the noise elimination shell, a first partition plate and a second partition plate are fixedly mounted in the noise elimination shell, and two ends of the first partition plate are fixedly connected with two ends of the second partition plate. The first partition plate and the second partition plate divide the interior of the silencing shell into an air inlet cavity, a middle cavity and an exhaust cavity, the middle cavity is filled with silencing glass fibers, an air inlet pipe, an air outlet pipe and an insertion pipe are further fixedly installed in the silencing shell, the input end of the air inlet pipe is fixedly communicated with the air inlet, and the output end of the air outlet pipe is fixedly communicated with the air outlet. The air inlet pipe, the air outlet pipe and the insertion pipe penetrate through the first partition plate and the second partition plate. The low-frequency noise can be eliminated, the exhaust sound quality of a vehicle at a low rotating speed is greatly improved, the exhaust back pressure of an engine at a high rotating speed is reduced to improve the fuel oil utilization rate, and the energy-saving effect is achieved.

Description

Technical Field

[0001] This utility model belongs to the field of engine noise reduction technology. Specifically, it relates to a noise reduction structure that eliminates low-frequency engine noise and reduces high-speed exhaust back pressure. Background Technology

[0002] Due to space constraints, some car mufflers cannot eliminate or shield low-frequency exhaust noise. The engine's low-frequency noise is directly transmitted to the tailpipe through the exhaust system, causing passengers inside the car or people outside to hear an extremely uncomfortable noise that presses against their eardrums. Increasing exhaust back pressure is a common method to eliminate this low-frequency exhaust noise, but this will increase the exhaust back pressure when the engine is running at high speed, which will directly lead to increased engine fuel consumption, exacerbate incomplete combustion in the cylinder, and reduce engine power performance.

[0003] Low-frequency exhaust noise refers to noise in the 30Hz-100Hz range of some engine exhaust noise, with wavelengths between 11.1 meters and 4.25 meters. Ordinary perforated pipe and baffle mufflers only have a good noise reduction effect on frequencies between 100Hz and 3000Hz, but their noise reduction for low-frequency noise below 100Hz is only less than 10dB. Exhaust back pressure is the resistance pressure of engine exhaust. When exhaust back pressure increases, engine exhaust is obstructed, thereby affecting engine power and increasing fuel consumption.

[0004] Currently, there are three main solutions for eliminating low-frequency roaring noise from car mufflers: The first solution involves bending and lengthening the inner tube of the muffler tailpipe inside the cylinder, thus reducing low-frequency exhaust noise. The advantage of this solution is that it doesn't require any changes to the external vehicle layout. The disadvantage is that the added small-radius bend requires special processing, resulting in more steps and higher costs. It also increases the difficulty of assembling the internal structure of the muffler, and it's difficult to bend the tube given the limited space in the muffler housing. The second solution involves lengthening the muffler tailpipe outside the cylinder, thus reducing low-frequency exhaust noise. The advantage of this solution is its simple process and low cost. The disadvantage is that it requires changes to the external muffler layout and a larger chassis space. The third solution involves increasing exhaust back pressure by adjusting the number of internal baffles, the size and percentage of openings, and the pipe diameter, opening position, size, and percentage. This can dissipate the energy transmitted by low-frequency exhaust noise. The advantage of this solution is its low cost and small space requirements. The disadvantage is that it simultaneously increases engine back pressure at high speeds, increasing engine fuel consumption.

[0005] There are two main solutions for reducing back pressure at high engine speeds: The first is to shorten the pipe, increase the pipe diameter, and reduce pipe bends to allow airflow to exit more smoothly. The disadvantage is that it reduces the muffler's ability to eliminate low-frequency roaring noise. The second is to increase the number of small holes in the baffle or increase the pipe diameter inside the muffler to increase the flow area and allow airflow to exit the cavity more smoothly. The disadvantage is that low-frequency roaring noise is difficult to eliminate and more costs are required to eliminate low-frequency noise.

[0006] Therefore, it is necessary to improve upon the shortcomings and defects of the existing technology and provide a noise reduction structure that eliminates low-frequency engine noise and reduces high-speed exhaust back pressure. Utility Model Content

[0007] The technical problem to be solved by this utility model is to overcome the shortcomings of the prior art and provide a noise reduction structure that can overcome or at least partially solve the above problems, thereby eliminating low-frequency engine noise and reducing high-speed exhaust back pressure.

[0008] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a noise reduction structure for eliminating low-frequency engine noise and reducing high-speed exhaust back pressure, characterized in that: it includes a noise reduction shell, an air inlet at the front end of the noise reduction shell, an air outlet at the rear end of the noise reduction shell, a first partition and a second partition fixedly installed inside the noise reduction shell, the two ends of the first partition and the second partition fixedly connected, the first partition and the second partition dividing the interior of the noise reduction shell into an air intake chamber, an intermediate chamber and an exhaust chamber, the intermediate chamber being filled with sound-absorbing glass fiber, an air intake pipe, an air outlet pipe and an insertion pipe fixedly installed inside the noise reduction shell, the input end of the air intake pipe being fixedly connected to the air inlet, the output end of the air outlet pipe being fixedly connected to the air outlet, the air intake pipe, the air outlet pipe and the insertion pipe all passing through the first partition and the second partition, a passive valve being fixedly installed at the output port of the insertion pipe; both the first partition and the second partition are provided with vent holes; the number of vent holes on the second partition is greater than the number of vent holes on the first partition, and the specifications of the vent holes are the same. To ensure that the airflow in the intake chamber flows to the exhaust chamber when the passive valve is closed, both the first and second partitions are provided with vents. To increase the airflow velocity through air pressure, the second partition has more vents than the first partition.

[0009] Furthermore, the ratio of the number of vents on the second partition to the number of vents on the first partition is 10~20:1.

[0010] Furthermore, the insertion tube has a vent hole in the middle cavity, which connects the inside and outside of the insertion tube.

[0011] Furthermore, the passive valve includes a valve body, a valve plate, a connecting plate, and a spring plate. The valve body is provided with a through hole connecting both ends of the valve body. One end of the connecting plate is connected to the valve body, and the other end of the connecting plate is connected to the valve plate. The middle part of the connecting plate is connected to the valve body through the spring plate. Through the elastic force of the spring plate, the valve plate can tightly cover the through hole on the valve body.

[0012] By adopting the above technical solution, this utility model has the following beneficial effects compared with the prior art:

[0013] This utility model is a muffler structure that eliminates low-frequency engine noise and reduces high-speed exhaust back pressure. It does not require modification to the external structure of the muffler, such as the baffle, muffler housing, high-frequency tube, etc. Only the number and state of the openings in the baffle need to be changed, an insertion tube and a passive valve need to be inserted, and the length of the tube and the opening parameters need to be adjusted. This allows for the creation of a muffler structure that can match different engines, eliminating low-frequency noise and reducing high-speed exhaust back pressure. While eliminating low-frequency noise and greatly improving the exhaust sound quality of the vehicle at low speeds, it also reduces high-speed exhaust back pressure, improving fuel efficiency and achieving energy saving.

[0014] The specific embodiments of this utility model will be described in further detail below with reference to the accompanying drawings. Attached Figure Description

[0015] In the attached diagram:

[0016] Figure 1 This is a schematic diagram of the overall structure of this utility model;

[0017] Figure 2 This is a schematic diagram of the internal front view structure of this utility model;

[0018] Figure 3 This is a schematic diagram of the internal rear view structure of this utility model;

[0019] Figure 4 This is a schematic diagram of the internal hidden sealing cavity plate structure of this utility model;

[0020] Figure 5 This is a schematic diagram of the insertion tube structure of this utility model;

[0021] Figure 6 This is a schematic diagram of the passive valve closing and opening structure of this utility model;

[0022] Figure 7 This is a schematic diagram of the experimental results of an embodiment of this utility model.

[0023] In the diagram: 1. Silencing housing; 101. Inlet chamber; 102. Intermediate chamber; 103. Exhaust chamber; 2. Inlet; 3. Outlet; 4. Sound-absorbing fiberglass; 5. First partition; 6. Second partition; 7. Inlet pipe; 8. Outlet pipe; 9. Insertion pipe; 10. Passive valve. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. The following embodiments are used to illustrate this utility model, but are not intended to limit the scope of this utility model.

[0025] Reference Figure 1-6 As shown, a noise reduction structure for eliminating low-frequency engine noise and reducing high-speed exhaust back pressure includes a noise reduction housing 1. The front end of the noise reduction housing 1 is provided with an air inlet 2, and the rear end of the noise reduction housing 1 is provided with an air outlet 3. A first partition 5 and a second partition 6 are fixedly installed inside the noise reduction housing 1. The two ends of the first partition 5 and the second partition 6 are fixedly connected. The first partition 5 and the second partition 6 divide the interior of the noise reduction housing 1 into an air intake chamber 101, an intermediate chamber 102 and an exhaust chamber 103. The intermediate chamber 102 is filled with sound-absorbing glass fiber 4. An air intake pipe 7, an air outlet pipe 8 and an insertion pipe 9 are also fixedly installed inside the noise reduction housing 1. The input end of the air intake pipe 7 is fixedly connected to the air inlet 2, and the output end of the air outlet pipe 8 is fixedly connected to the air outlet 3. The air intake pipe 7, the air outlet pipe 8 and the insertion pipe 9 all pass through the first partition 5 and the second partition 6. A passive valve 10 is fixedly installed at the output port of the insertion pipe 9.

[0026] Both the first partition 5 and the second partition 6 are provided with vent holes. The second partition 6 has more vent holes than the first partition 5. When the airflow in the intake chamber 101 enters the intermediate chamber 102, because the first partition 5 has fewer vent holes than the second partition 6, the airflow will stagnate in the intake chamber 101 and the intermediate chamber 102, forming a pressure difference with the exhaust chamber 103. When the engine speed is low, the pressure difference cannot push the passive valve 10 to open, and a resistance silencing structure will be formed in the intake chamber 101 and the intermediate chamber 102, and the exhaust will form a high back pressure, thereby eliminating the low-frequency roaring sound. When the engine speed is high, the pressure difference will continue to increase, pushing the passive valve 10 to open, and the airflow will enter the exhaust chamber 103 from the insertion pipe 9. The exhaust back pressure will decrease, thereby reducing the back pressure of the engine at high speed and reducing the engine fuel consumption. The passive valve 10 is a mechanical valve composed of a valve body, a valve plate, a connecting plate, and a spring plate. Under normal circumstances, the valve plate is tightly attached to the valve body under the action of the spring plate, and the valve is in the closed state. When the pressure difference in the cavity reaches a certain value, the spring plate and the valve plate open. The greater the pressure difference, the greater the opening angle of the valve plate.

[0027] The interior of the muffler housing 1 is divided into three closed cavities by the first partition 5 and the second partition 6. Only the intake pipe 7, the exhaust pipe 8, and the insertion pipe 9 are connected and pass through the intake cavity 101, the intermediate cavity 102, and the exhaust cavity 103. At low speeds, some airflow enters the exhaust cavity 103 from the small hole in the intake pipe 7, and some airflow enters the intake cavity 101 from the output end of the intake pipe 7, and then enters the exhaust cavity 103 through the ventilation holes of the first partition 5 and the second partition 6. Due to the small airflow area, a resistive noise reduction structure is formed in the intake cavity 101 and the intermediate cavity 102, eliminating low-frequency noise and greatly improving the exhaust sound quality of the vehicle at low speeds.

[0028] When the engine is running at high speed, the pressure in the intake chamber 101 continues to rise. The amount of airflow entering the first baffle 5 is much less than the amount of airflow exiting. When the air pressure reaches a certain value, the passive valve 10 opens, the flow area increases and the exhaust back pressure is reduced, thereby improving fuel efficiency and achieving energy saving.

[0029] The final experimental results are as follows Figure 7 As shown, the silencer reduces noise levels below 30Hz-100Hz by more than 18dB.

[0030] In the above embodiments, the ratio of the number of vent holes on the second partition to the number of vent holes on the first partition is 10~20:1, and the specifications of the vent holes are consistent, that is, the cross-sectional area of ​​the vent holes is the same. In this embodiment, the inner diameter of the vent hole is 3.5mm, and the ratio of the number of vent holes is matched according to different utility models.

[0031] In the above embodiment, the passive valve includes a valve body, a valve plate, a connecting plate, and a spring plate. The valve body has a through hole connecting both ends. One end of the connecting plate is connected to the valve body, and the other end is connected to the valve plate. The middle of the connecting plate is connected to the valve body via a spring plate. Through the elastic force of the spring plate, the valve plate can tightly cover the through hole on the valve body. The spring plate ensures that the valve plate only opens when the air pressure reaches a certain value.

[0032] This invention does not require modification to the external structure of the muffler, such as the baffle, muffler housing, and high-frequency tube. It only requires changing the number and state of the openings in the baffle, inserting an insertion tube and a passive valve, and adjusting the length of the tubes and the opening parameters. This allows for the creation of a muffler structure that can match different engines, eliminating low-frequency roar and reducing exhaust back pressure at high engine speeds. While eliminating low-frequency roar and greatly improving the exhaust sound quality at low speeds, it also reduces exhaust back pressure at high engine speeds, improving fuel efficiency and achieving energy-saving effects.

[0033] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any modifications or improvements made by those skilled in the art without departing from the concept of the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A noise reduction structure for eliminating low-frequency engine noise and reducing high-speed exhaust back pressure, characterized in that: The device includes a muffler housing (1), with an air inlet (2) at the front end and an air outlet (3) at the rear end. A first partition (5) and a second partition (6) are fixedly installed inside the muffler housing (1). The first partition (5) and the second partition (6) are fixedly connected at both ends. The first partition (5) and the second partition (6) divide the interior of the muffler housing (1) into an air inlet chamber (101), an intermediate chamber (102), and an exhaust chamber (103). The intermediate chamber (102) is filled with sound-absorbing glass fiber (4). An air inlet pipe is also fixedly installed inside the muffler housing (1). 7) Air outlet pipe (8) and insertion pipe (9), the input end of the air inlet pipe (7) is fixedly connected to the air inlet (2), the output end of the air outlet pipe (8) is fixedly connected to the air outlet (3), the air inlet pipe (7), the air outlet pipe (8) and the insertion pipe (9) all pass through the first partition (5) and the second partition (6), and a passive valve (10) is fixedly installed at the output port of the insertion pipe (9); the first partition (5) and the second partition (6) are both provided with ventilation holes; the number of ventilation holes on the second partition (6) is more than the number of ventilation holes on the first partition (5), and the specifications of the ventilation holes are the same.

2. The noise reduction structure for eliminating low-frequency engine noise and reducing high-speed exhaust back pressure according to claim 1, characterized in that: The ratio of the number of vent holes on the second partition (6) to the number of vent holes on the first partition (5) is 10~20:

1.

3. The noise reduction structure for eliminating low-frequency engine noise and reducing high-speed exhaust back pressure according to claim 1, characterized in that: The insertion tube (9) has a vent hole in the middle cavity (102) that connects the inside and outside of the insertion tube (9).

4. The noise reduction structure for eliminating low-frequency engine noise and reducing high-speed exhaust back pressure according to claim 1, characterized in that: The passive valve (10) includes a valve body, a valve plate, a connecting plate and a spring plate. The valve body is provided with a through hole that connects the two ends of the valve body. One end of the connecting plate is connected to the valve body, and the other end of the connecting plate is connected to the valve plate. The middle part of the connecting plate is connected to the valve body through the spring plate. Through the elastic force of the spring plate, the valve plate can tightly cover the through hole on the valve body.

Images