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

Abstract

The invention discloses a silencing structure for eliminating low-frequency roar of an engine and reducing high-rotation-speed exhaust back pressure, which comprises a silencing shell, an air inlet is formed in the front end of the silencing shell, an air outlet is formed in the rear end of the silencing shell, a first partition plate and a second partition plate are fixedly mounted in the silencing 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 the low rotating speed is greatly improved, meanwhile, the high-rotating-speed exhaust back pressure of an engine is reduced, the fuel oil utilization rate is increased, and the energy-saving effect is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of engine silencing, and in particular relates to a silencing structure for eliminating low-frequency roar of an engine and reducing exhaust back pressure at high speed. Background Art

[0002] Due to space limitations, some car mufflers are unable to eliminate or shield low-frequency exhaust noise. The low-frequency noise of the engine is directly transmitted to the tail pipe through the exhaust system. Passengers inside or outside the car will hear an extremely uncomfortable noise that presses on the eardrum. In order to eliminate this low-frequency exhaust noise, increasing the exhaust back pressure is a common method, 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, aggravated and worsened incomplete combustion in the cylinder, and reduced engine power performance.

[0003] Low-frequency exhaust noise refers to the noise in the 30Hz-100Hz area in some engine exhaust noise, and its wavelength length is between 11.1 meters and 4.25 meters. Ordinary perforated tube plus baffle structure muffler only has a good silencing effect on 100Hz-3000Hz, but the silencing effect on low-frequency noise below 100Hz is only below 10dB; exhaust back pressure is the resistance pressure of engine exhaust. When the exhaust back pressure increases, the engine exhaust is not smooth, which affects the engine's power and increases the engine's fuel consumption.

[0004] At present, there are three main solutions for eliminating the low-frequency roar of automobile mufflers: the first solution is to bend the inner tube inside the cylinder to lengthen the muffler tail pipe, so as to reduce the low-frequency exhaust noise. The advantage of this solution is that no changes are required to any layout outside the car. The disadvantage is that the small radius bend pipe added needs to be processed through special processes, with many processes and high costs. The internal structure of the muffler is more difficult to assemble. Under the premise of limited space in the muffler package, it is also difficult to bend the pipe out; the second solution is to lengthen the muffler tail pipe outside the cylinder, so as to reduce the low-frequency exhaust noise. The advantage of this solution is simple process and low cost. The disadvantage is that the muffler layout outside the car needs to be changed and the chassis needs a large space. The third solution is to increase the exhaust back pressure by adjusting the number of baffles inside the cylinder, the size of the opening, the opening rate, the pipe diameter, the position of the opening, the size of the opening, and the opening rate, so as to consume the transmission energy of the low-frequency exhaust noise. The advantage of this solution is that the cost is low and the space requirement is low. The disadvantage is that it will increase the high-speed back pressure of the engine and increase the engine fuel consumption.

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

[0006] Therefore, it is necessary to improve the deficiencies and defects of the prior art and provide a muffler structure that can eliminate the low-frequency roar of the engine and reduce the exhaust back pressure at high speeds. Summary of the invention

[0007] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a silencer structure that can overcome the above problems or at least partially solve the above problems and eliminate the low-frequency roar of the engine and reduce the exhaust back pressure at high speed.

[0008] In order to solve the above technical problems, the technical solution adopted by the present invention is: a muffler structure for eliminating low-frequency roar of an engine and reducing high-speed exhaust back pressure, characterized in that: it includes a muffler shell, the front end of the muffler shell is provided with an air inlet, the rear end of the muffler shell is provided with an air outlet, a first baffle and a second baffle are fixedly installed in the muffler shell, the first baffle and the second baffle are fixedly connected at both ends, the first baffle and the second baffle divide the interior of the muffler shell into an air inlet chamber, an intermediate chamber and an exhaust chamber, the intermediate chamber is filled with the muffler glass fiber, an air inlet pipe, an air outlet pipe and an insertion pipe are also fixedly installed in the muffler shell, the input end of the air inlet pipe is fixedly connected to the air inlet, the output end of the air outlet pipe is fixedly connected to the air outlet, the air inlet pipe, the air outlet pipe and the insertion pipe all pass through the first baffle and the second baffle, and a passive valve is fixedly installed on the output port of the insertion pipe; the first baffle and the second baffle are both provided with air vents; the number of air vents on the second baffle is more than that on the first baffle, and the specifications of the air vents are consistent. In order to allow the airflow in the air inlet cavity to flow to the air outlet cavity when the passive valve is closed, both the first baffle and the second baffle are provided with air holes. In order to increase the airflow velocity by air pressure, the number of air holes on the second baffle is greater than that on the first baffle.

[0009] Furthermore, the ratio of the number of ventilation holes on the second partition plate to the number of ventilation holes on the first partition plate is 10-20:1.

[0010] Furthermore, a vent hole is provided in the middle cavity of the insertion tube to connect 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 sheet. A through hole is provided on the valve body to connect 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 sheet. Through the elastic force of the spring sheet, the valve plate can tightly cover the through hole on the valve body.

[0012] After adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0013] The present invention discloses a silencer structure for eliminating low-frequency roar of an engine and reducing exhaust back pressure at high speed. The structure does not need to change the external structure of the silencer, the original parts such as the partition, the silencer shell, and the high-frequency tube. It only needs to change the number of openings of the partition, insert the insertion tube and the passive valve, and adjust the length of the pipe and the opening parameters at the same time. Then, a silencer structure can be formed that can match different engines and can eliminate low-frequency roar and reduce exhaust back pressure at high speed of the engine. While eliminating the low-frequency roar and greatly improving the exhaust sound quality of the vehicle at low speed, the exhaust back pressure of the engine at high speed is reduced, the fuel utilization rate is improved, and the energy-saving effect is achieved.

[0014] The specific implementation modes of the present invention are further described in detail below in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In the attached picture:

[0016] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0017] Figure 2 It is a schematic diagram of the internal front structure of the present invention;

[0018] Figure 3 It is a schematic diagram of the internal rear view structure of the present invention;

[0019] Figure 4 It is a schematic diagram of the structure of the internal hidden sealed cavity plate of the present invention;

[0020] Figure 5 It is a schematic diagram of the insertion tube structure of the present invention;

[0021] Figure 6 It is a schematic diagram of the passive valve closing and opening structure of the present invention;

[0022] Figure 7 It is a schematic diagram of experimental results of an embodiment of the present invention.

[0023] In the figure: 1. Silencer shell; 101. Air inlet chamber; 102. Middle chamber; 103. Exhaust chamber; 2. Air inlet; 3. Air outlet; 4. Silencer glass fiber; 5. First baffle; 6. Second baffle; 7. Air inlet pipe; 8. Air outlet pipe; 9. Insertion pipe; 10. Passive valve. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The following embodiments are used to illustrate the present invention but are not used to limit the scope of the present invention.

[0025] Reference Figure 1-6 As shown, a silencer structure for eliminating low-frequency roar of an engine and reducing exhaust back pressure at high speed comprises a silencer shell 1, an air inlet 2 is arranged at the front end of the silencer shell 1, an air outlet 3 is arranged at the rear end of the silencer shell 1, a first baffle 5 and a second baffle 6 are fixedly installed in the silencer shell 1, both ends of the first baffle 5 and the second baffle 6 are fixedly connected, the first baffle 5 and the second baffle 6 divide the interior of the silencer shell 1 into an air inlet chamber 101, an intermediate chamber 102 and an exhaust chamber 103, the intermediate chamber 102 is filled with silencer glass fiber 4, an air inlet pipe 7, an air outlet pipe 8 and an insertion pipe 9 are also fixedly installed in the silencer shell 1, 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 baffle 5 and the second baffle 6, and a passive valve 10 is fixedly installed at the output port of the insertion pipe 9.

[0026] Both the first baffle 5 and the second baffle 6 are provided with air vents, and the number of air vents on the second baffle 6 is greater than that on the first baffle 5. When the airflow in the air intake chamber 101 enters the middle chamber 102, because the number of air vents on the first baffle 5 is less than that on the second baffle 6, the airflow will be retained in the air intake chamber 101 and the middle chamber 102, and a pressure difference will be formed with the air outlet chamber 103. When the engine speed is low, the pressure difference cannot push the passive valve 10 to open, and a resistive silencer structure will be formed in the air intake chamber 101 and the middle chamber 102, and the exhaust will form a high back pressure, thereby eliminating the low-frequency roar. When the engine speed is high, the pressure difference increases continuously, pushing the passive valve 10 to open, and the airflow enters the exhaust chamber 103 from the insertion tube 9, and the exhaust back pressure will decrease, thereby reducing the high-speed back pressure of the engine 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. Under normal circumstances, the valve plate is tightly attached to the valve body under the action of the spring, and the valve is in a closed state. When the pressure difference in the cavity reaches a certain value, the spring and the valve plate open. The greater the pressure difference, the greater the angle at which the valve plate opens.

[0027] The interior of the silencer housing 1 is divided into three closed cavities by the first baffle 5 and the second baffle 6. Only the air inlet pipe 7, the air outlet pipe 8 and the insertion pipe 9 are connected through the air inlet cavity 101, the middle cavity 102 and the exhaust cavity 103. At low speeds, part of the airflow enters the exhaust cavity 103 from the small hole of the air inlet pipe 7, and part of the airflow enters the air inlet cavity 101 from the output end of the air inlet pipe 7, and then enters the exhaust cavity 103 through the air vents of the first baffle 5 and the second baffle 6. Since the airflow area is very small, a resistive silencer structure is formed in the air inlet cavity 101 and the middle cavity 102 to eliminate low-frequency noise, thereby 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, and the input amount of airflow in the first partition 5 is much smaller than the output flow. 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 the fuel utilization rate and achieving energy saving effect.

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

[0030] In the above embodiment, the ratio of the number of vent holes on the second partition plate to the number of vent holes on the first partition plate is 10 to 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 holes is 3.5 mm, and the ratio of the number of vent holes is matched according to different invention machines.

[0031] In the above embodiment, the passive valve includes a valve body, a valve plate, a connecting plate and a spring plate. A through hole is provided on the valve body to connect 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. The spring plate allows the valve plate to open only when the air pressure reaches a certain value.

[0032] The present invention does not require changes to the external structure of the muffler, the original parts such as the partition, the muffler shell, and the high-frequency tube. It only needs to change the number of openings of the partition, insert the insertion tube and the passive valve, and adjust the length of the pipe and the opening parameters. Then, a muffler structure that can match different engines and can eliminate low-frequency roars and reduce the exhaust back pressure of the engine at high speeds can be formed. While eliminating low-frequency roars to greatly improve the exhaust sound quality of the vehicle at low speeds, the exhaust back pressure of the engine at high speeds can be reduced, the fuel utilization rate can be improved, and the energy-saving effect can be achieved.

[0033] The above is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any modification or improvement made by any technician familiar with this patent without departing from the inventive concept of this patent shall fall within the scope of protection required by the present invention.

Claims

1. A muffler structure for eliminating low-frequency roar of an engine and reducing exhaust back pressure at high speed, characterized in that: The invention comprises a muffler shell (1), wherein the front end of the muffler shell (1) is provided with an air inlet (2), the rear end of the muffler shell (1) is provided with an air outlet (3), a first partition plate (5) and a second partition plate (6) are fixedly installed in the muffler shell (1), the first partition plate (5) and the second partition plate (6) are fixedly connected at both ends, the first partition plate (5) and the second partition plate (6) divide the interior of the muffler shell (1) into an air inlet chamber (101), an intermediate chamber (102) and an exhaust chamber (103), the intermediate chamber (102) is filled with the muffler glass fiber (4), and an air inlet pipe is also fixedly installed in the muffler shell (1). (7), an air outlet pipe (8) and an 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 plate (5) and the second partition plate (6), and a passive valve (10) is fixedly installed on the output port of the insertion pipe (9); the first partition plate (5) and the second partition plate (6) are both provided with ventilation holes; the number of ventilation holes on the second partition plate (6) is greater than the number of ventilation holes on the first partition plate (5), and the specifications of the ventilation holes are consistent.

2. A muffler structure for eliminating low-frequency roar of an engine and reducing exhaust back pressure at high speed according to claim 1, characterized in that: The ratio of the number of ventilation holes on the second partition plate (6) to the number of ventilation holes on the first partition plate (5) is 10 to 20:

1.

3. A muffler structure for eliminating low-frequency roar of an engine and reducing exhaust back pressure at high speed according to claim 1, characterized in that: The insertion tube (9) is provided with a vent hole in the middle cavity (102) to connect the inside and outside of the insertion tube (9).

4. A muffler structure for eliminating low-frequency roar of an engine and reducing exhaust back pressure at high speed according to claim 1, characterized in that: The passive valve (10) comprises a valve body, a valve plate, a connecting plate and a spring plate. The valve body is provided with a through hole connecting 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 via the spring plate. Through the elastic force of the spring plate, the valve plate can tightly cover the through hole on the valve body.

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