Tractor silencer
By introducing Laval tube modules, variable diameter resonant cavity groups, and perforated baffle structures into the tractor muffler, the problems of insufficient low-frequency suppression, excessive back pressure, and thermal deformation failure in traditional mufflers have been solved, achieving more efficient noise reduction and improved engine performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-14
- Publication Date
- 2026-03-10
AI Technical Summary
Traditional tractor mufflers have shortcomings in low-frequency suppression, excessive back pressure, and thermal deformation failure, making it difficult to effectively reduce noise and maintain engine efficiency.
By employing Laval tube modules, variable diameter resonant cavity groups, and perforated partition structures, combined with an exponentially gradual diameter design and composite ceramic coating, efficient noise cancellation and thermal stress resistance are achieved through acoustic wave phase interference, thermo-acoustic coupling compensation, and acoustic impedance modulation.
It effectively broadens the Helmholtz resonance frequency band, reduces airflow noise, reduces exhaust resistance, improves noise reduction performance, reduces the impact of thermal deformation, and improves engine power efficiency.
Smart Images
Figure CN223984512U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to agricultural machinery exhaust noise reduction technical field, concretely relates to a tractor muffler. BACKGROUND
[0002] Traditional tractor muffler adopts resistance-resistance composite structure, and has the following defects: 1. low frequency suppression is insufficient: Helmholtz resonance cavity frequency is fixed, and it is difficult to cover tractor engine 100-500Hz characteristic noise; 2. Back pressure is too high: multiple cavity series structure leads to exhaust resistance increase, and engine power loss reaches 5-8%; 3. Thermal deformation failure: cavity thermal expansion under high load condition causes structural deformation, and noise reduction performance attenuates. SUMMARY
[0003] The utility model discloses to the defects and insufficient of prior art, provide a kind of tractor muffler with reasonable design, it can solve the above-mentioned defects.
[0004] To achieve the above object, the utility model adopts the following technical scheme: it contains intake pipe, flange one is welded and fixed in the front end of intake pipe, laval tube is welded and connected in the rear end of intake pipe, transition connecting pipe is connected with the rear end of laval tube through flange two, the rear end of transition connecting pipe is connected with variable-diameter resonance cavity group through flange three, two perforated partitions are welded in variable-diameter resonance cavity group, and exhaust pipe is welded and connected in the rear end of variable-diameter resonance cavity group.
[0005] Preferably, the laval tube module is composed of a converging section, a throat section, and a diverging section, the ratio of the inlet diameter Dm of the converging section to the throat diameter Dt is 0.6, the diverging angle of the diverging section is 8°, and the total length of the laval tube is 300 mm.
[0006] Preferably, the variable-diameter resonance cavity group and the outlet of the diverging section of the laval tube are connected by a conical transition connecting pipe, the cavity diameter of the variable-diameter resonance cavity group changes continuously along the axial direction according to an exponential function, and the diameter change function is D(x) = 150e0.03x.
[0007] Preferably, the inner wall of the diverging section of the laval tube is provided with a plurality of spiral flow guide grooves, the pitch of the spiral flow guide grooves is 60 mm, the depth is 2 mm, the number of the spiral flow guide grooves is 4, the root of the spiral flow guide grooves is smoothly connected to the inner wall of the diverging section of the laval tube through a gradually changing round corner, and a corrugated buffer section is arranged at intervals along the length direction of the spiral flow guide grooves.
[0008] Preferably, the two perforated partitions are a front partition and a rear partition, respectively, which divide the variable-diameter resonance cavity group into three chambers, the front partition has a perforation rate of 25-35%, a hole diameter of 3 mm, and is arranged in a square shape; the rear partition has a perforation rate of 10-20%, a hole diameter of 5 mm, and is arranged in a honeycomb shape.
[0009] Preferably, the outer wall of the variable-diameter resonant cavity group is provided with a corrugated expansion joint, the corrugation depth is 4mm, and the pitch is 25mm; the inner wall of the throat and the expansion section of the Laval tube is coated with a ZrO2-Al2O3 composite ceramic coating, the coating thickness is 70-90μm, and the porosity is ≤5%.
[0010] After the above structure is adopted, the beneficial effects of the utility model are:
[0011] 1. The utility model discloses a Laval tube module, which reduces the airflow velocity gradient through a contraction-expansion structure and realizes high-frequency noise cancellation by utilizing sound wave phase interference.
[0012] 2. The utility model discloses a variable-diameter resonant cavity group, which widens the Helmholtz resonance frequency band through exponential diameter gradual change design and adjusts and controls acoustic impedance in combination with two perforated baffle plates.
[0013] 3. The utility model discloses a thermal-acoustic coupling compensation, which cancels thermal stress by utilizing a corrugated expansion joint and reduces the influence of carbon deposition on acoustic performance by utilizing a composite ceramic coating. DRAWINGS
[0014] Figure 1 is the three-dimensional view of the overall structure of the muffler of the utility model;
[0015] Figure 2 is the sectional view of the overall structure of the muffler of the utility model;
[0016] Figure 3 is the layout diagram of the spiral flow guide groove of the utility model;
[0017] Figure 4 is the front baffle main view of the utility model;
[0018] Figure 5 is the rear baffle main view of the utility model.
[0019] MARKS OF THE DRAWINGS:
[0020] 1. Flange one; 2. Inlet pipe; 3. Laval tube; 4. Flange two; 5. Transition connecting pipe; 6. Flange three; 7. Variable-diameter resonant cavity group; 8. Exhaust pipe; 9. Front baffle; 10. Rear baffle; 11. Spiral flow guide groove. DETAILED DESCRIPTION
[0021] Clearly and completely describe the technical scheme in the embodiments of the utility model with reference to the drawings in the embodiments of the utility model, obviously, the described embodiments only are a part of embodiments of the utility model, and not all embodiments. Based on the embodiments in the utility model, all other embodiments obtained by the ordinary skill in the art without making creative labor belong to the range of protection of the utility model.
[0022] Referring to Figures 1-5 As shown in the figure, it comprises an air inlet pipe 2, a flange one 1 is welded and fixed at the front end of the air inlet pipe 2, a Laval pipe 3 is welded and connected at the rear end of the air inlet pipe 2, a transition connecting pipe 5 is connected at the rear end of the Laval pipe 3 through a flange two 4, and a variable-diameter resonance cavity group 7 is connected at the rear end of the transition connecting pipe 5 through a flange three 6, and an exhaust pipe 8 is welded and connected at the rear end of the variable-diameter resonance cavity group 7; two perforated partitions are welded in the variable-diameter resonance cavity group 7, which are a front partition 9 and a rear partition 10, and the two partitions divide the variable-diameter resonance cavity group 7 into three chambers, the perforation rate of the front partition 9 is 25-35%, the hole diameter is 3mm, and the holes are arranged in a square shape; the perforation rate of the rear partition 10 is 10-20%, the hole diameter is 5mm, and the holes are arranged in a honeycomb shape; the front partition 9 is welded at a position 150mm away from the inlet of the variable-diameter resonance cavity group 7, and the rear partition 10 is welded at a position 450mm away from the inlet of the variable-diameter resonance cavity group 7; the sound impedance is adjusted by the two perforated partitions;
[0023] The Laval pipe 3 module is composed of a converging section, a throat section and a diverging section, the ratio of the inlet diameter Dm=120mm of the converging section to the throat diameter Dt=72mm is 0.6, the diverging angle of the diverging section is 8°, and the total length of the Laval pipe 3 is 300mm; the airflow velocity gradient is reduced by the converging-diverging structure, and high-frequency noise cancellation is realized by using sound wave phase interference;
[0024] Between the variable-diameter resonance cavity group 7 and the outlet of the diverging section of the Laval pipe 3, a conical transition connecting pipe 5 is connected, the cavity diameter of the variable-diameter resonance cavity group 7 changes continuously along the axial direction according to an exponential function, and the diameter change function is D(x) = 150e0.03x; the exponential gradual diameter design is used to broaden the Helmholtz resonance frequency band;
[0025] A plurality of spiral flow guide grooves 11 are arranged on the inner wall of the diverging section of the Laval pipe 3, the pitch of the spiral flow guide grooves 11 is 60mm, the depth is 2mm, the number of the spiral flow guide grooves 11 is 4, the root of the spiral flow guide grooves 11 is smoothly transitioned to the inner wall of the diverging section of the Laval pipe 3 through a gradual round corner, and corrugated buffer sections are arranged at intervals along the length direction of the spiral flow guide grooves 11;
[0026] The outer wall of the variable-diameter resonant cavity group 7 is provided with a corrugated expansion joint, the corrugated depth is 4mm, and the interval is 25mm; the inner wall of the throat and the expansion section of the Laval tube 3 is coated with a ZrO2-Al2O3 composite ceramic coating, the coating thickness is 70-90μm, the porosity is ≤5%, the thermal stress is offset through the corrugated expansion joint, and the composite ceramic coating reduces the influence of carbon deposition on the acoustic performance.
[0027] In use, the high-temperature gas discharged by the engine first passes through the intake pipe 2 connected with the flange 1, enters the converging section of the Laval tube 3 from the intake pipe 2, accelerates the flow rate and reduces the static pressure, then enters the diverging section from the converging section through the throat, the gas flow rate is reduced, the pressure is recovered, the spiral flow guide groove 11 in the diverging section guides the sound wave reflection, 180° phase difference is formed in the frequency band of 500-2000Hz, active interference noise reduction is realized,
[0028] The exhaust gas enters the variable-diameter resonant cavity group 7 with the diameter D(x) = 150e0.03x, the flow rate gradient is slowed down, the turbulent regenerative noise is reduced, the front baffle 9 absorbs the noise of 80-500Hz through Helmholtz resonance, and the rear baffle 10 can absorb the noise of 500-2500Hz, the exhaust gas is smoothly discharged at 0.1 Mach through the tail pipe, and the airflow pulsation is reduced to ±2%.
[0029] It should be understood that the above specific embodiments of the utility model are only used for example or explanation of the principle of the utility model, and do not constitute the limitation of the utility model. Therefore, any modification, equivalent replacement, improvement, etc. made without deviating from the spirit and scope of the utility model should be included in the protection scope of the utility model. In addition, the appended claims of the utility model are intended to cover all changes and modifications falling into the scope and boundary of the appended claims, or the equivalent forms of such scope and boundary.
Claims
1. A tractor muffler comprising an inlet pipe (2), characterized in that: The flange one (1) is welded and fixed at the front end of the air inlet pipe (2), the Laval pipe (3) is welded and connected at the rear end of the air inlet pipe (2), the Laval pipe (3) is connected with the transition connecting pipe (5) through the flange two (4) at the rear end, and the rear end of the transition connecting pipe (5) is connected with the variable-diameter resonance cavity group (7) through the flange three (6), two perforated partitions are welded in the variable-diameter resonance cavity group (7), and the exhaust pipe (8) is welded and connected at the rear end of the variable-diameter resonance cavity group (7).
2. A tractor muffler according to claim 1, characterized in that: The Laval pipe (3) module is composed of a contraction section, a throat section and an expansion section, the ratio of the inlet diameter Dm=120mm of the contraction section to the throat diameter Dt=72mm is 0.6, the expansion angle of the expansion section is 8°, and the total length of the Laval pipe (3) is 300mm.
3. A tractor muffler according to claim 2, characterised in that: The variable-diameter resonance cavity group (7) is connected with the outlet of the expansion section of the Laval pipe (3) through the conical transition connecting pipe (5), the cavity diameter of the variable-diameter resonance cavity group (7) changes continuously along the axial direction according to an exponential function, and the diameter change function is D(x)=150e0.03x.
4. A tractor muffler according to claim 3, characterised in that: The expansion section of the Laval pipe (3) is provided with a plurality of spiral guide grooves (11), the pitch of the spiral guide groove (11) is 60mm, the depth is 2mm, the number of the spiral guide groove (11) is 4, the root of the spiral guide groove (11) is smoothly connected with the inner wall of the expansion section of the Laval pipe (3) through a gradually changing round corner, and a corrugated buffer section is arranged along the length direction of the spiral guide groove (11).
5. A tractor muffler according to claim 1, wherein: The two perforated partitions are respectively a front partition (9) and a rear partition (10), which divide the variable-diameter resonance cavity group (7) into three chambers, the front partition (9) has a perforation rate of 25-35%, a hole diameter of 3mm and a square arrangement; the rear partition (10) has a perforation rate of 10-20%, a hole diameter of 5mm and a honeycomb arrangement.
6. A tractor muffler according to claim 2, characterized in that: The outer wall of the variable-diameter resonance cavity group (7) is provided with a corrugated expansion joint, the corrugated depth is 4mm, and the pitch is 25mm; the throat section and the expansion section of the Laval pipe (3) are coated with a ZrO2-Al2O3 composite ceramic coating, the coating thickness is 70-90μm, and the porosity is ≤5%.