Vibration isolation and noise reduction device for low-noise diesel engine room of diesel locomotive

Abstract

The invention relates to the technical field of internal combustion locomotive noise control, in particular to an internal combustion locomotive low-noise diesel engine cabin vibration isolation and noise reduction device which comprises a composite vibration isolation material layer which comprises a surface PU wear-resistant layer, a middle sponge sound absorption layer and bottom damping glue. The vibration isolation base comprises a double-layer elastic support and a metal rubber composite vibration isolator; the cab acoustic coating structure is arranged in the cab wall plate; the Helmholtz resonant cavity array is arranged on the inner wall of the intake and exhaust pipeline of the diesel engine room; the active noise reduction system comprises a plurality of error microphones and a plurality of secondary sound source loudspeakers, through application of the composite vibration isolation material layer, wide-frequency-band noise control is achieved, particularly, the sound absorption coefficient can reach 0.7 or above under the frequency of 1000 Hz, the sound insulation index exceeds 25 dB, and the sound environment of a cab is effectively improved.

Description

Technical Field

[0001] This invention relates to the field of noise control technology for internal combustion locomotives, and more specifically to a low-noise diesel engine compartment vibration isolation and noise reduction device for internal combustion locomotives. Background Technology

[0002] Diesel locomotives are widely used in China's railway transportation system. As a major type of medium-sized shunting diesel locomotive, they are known for their stable and reliable performance. However, traditional diesel locomotives suffer from significant noise pollution during long-term operation, especially the noise generated in the diesel engine compartment, which poses a serious threat to the health of drivers. According to relevant survey data, the average noise level in the cab of a diesel locomotive is approximately 82 dB(A), exceeding the 75 dB(A) standard stipulated in the "Noise Limits for Railway Locomotives and Rolling Stock" (GB / T 3450-2018). Long-term exposure to this environment significantly increases the risk of hearing damage for drivers.

[0003] In existing technologies, locomotives use a two-stage air filter consisting of a cyclone separator and a steel mesh, which suffers from dust penetration leading to diesel engine wear. Meanwhile, traditional noise control measures rely mainly on simple sound insulation panels or sound-absorbing materials, offering limited effectiveness in controlling low-frequency noise, especially in the 50-500Hz range, where it is almost impossible to effectively suppress low-frequency noise. Furthermore, existing vibration isolation measures typically employ only single spring dampers or rubber pads, resulting in a vibration transmission rate as high as 30%, leading to poor overall noise control performance for the locomotive.

[0004] Therefore, there is an urgent need to develop a comprehensive low-noise diesel engine compartment vibration isolation and noise reduction device. Through the synergistic effect of multiple technical approaches, it can effectively reduce the noise pollution of internal combustion locomotives, protect the health of drivers, and extend the service life of the equipment. Summary of the Invention

[0005] The purpose of this invention is to provide a low-noise diesel engine compartment vibration isolation and noise reduction device for internal combustion locomotives. Through a triple technical approach of materials, structure, and active control, it solves the problems of excessive noise in the cab of traditional internal combustion locomotives and diesel engine wear, reducing cab noise from 82dB(A) to 68dB(A), with a comprehensive noise reduction of 14dB(A), while extending the diesel engine overhaul cycle and reducing maintenance costs.

[0006] This invention proposes a vibration isolation and noise reduction device for the low-noise diesel engine compartment of an internal combustion locomotive, comprising:

[0007] A composite vibration isolation material layer, comprising a surface PU wear-resistant layer, a middle sponge sound-absorbing layer, and a bottom damping adhesive;

[0008] Vibration isolation base, the vibration isolation base comprising a double-layer elastic support and a metal-rubber composite vibration isolator;

[0009] The cab acoustic enclosure structure is disposed within the cab wall panel;

[0010] Helmholtz resonant cavity array, wherein the Helmholtz resonant cavity array is disposed on the inner wall of the intake and exhaust pipes of the diesel engine compartment; and

[0011] An active noise cancellation system, comprising multiple error microphones and multiple secondary sound source speakers.

[0012] Preferably, the thickness of the middle sponge sound-absorbing layer in the composite vibration isolation material layer is 3mm. The composite vibration isolation material layer is enhanced by nanotechnology, and the sound absorption coefficient reaches more than 0.7 at a frequency of 1000Hz, the sound insulation exceeds 25dB, and the damping coefficient is 0.08 (at a frequency of 100Hz).

[0013] Preferably, the metal-rubber composite vibration isolator in the vibration isolation base is configured to reduce the vibration transmission rate of the diesel engine from 30% to below 12%, and the stiffness distribution of the support point is optimized through finite element simulation.

[0014] Preferably, the acoustic covering structure of the cab includes gradient density sound-absorbing cotton and a micro-perforated plate resonant structure. The density of the gradient density sound-absorbing cotton is 80-120 kg / m³, which reduces noise in the 125-4000 Hz frequency band by 8-15 dB.

[0015] Preferably, the Helmholtz resonant cavity array is used to specifically attenuate the peak frequency of low-frequency noise in the 200-800Hz range.

[0016] Preferably, the active noise cancellation system includes four error microphones and eight secondary sound source speakers, and uses the LMS algorithm to achieve real-time cancellation of low-frequency noise in the 50-500Hz range.

[0017] Preferably, a constraint layer damping treatment structure is also included, which is disposed on the vehicle body floor and includes a 2mm thick high loss factor putty. The high loss factor putty has a loss factor η≥0.35 and is used to reduce the structural sound radiation by 5dB.

[0018] Preferably, the cooling fan structure is also included, which comprises 7 non-equidistant blades and a shroud with a curvature radius R ≥ 150 mm, thereby shifting the peak value of the fan noise spectrum from 630 Hz to over 1000 Hz.

[0019] Preferably, 12 sets of three-way vibration isolators are installed between the diesel engine and the vehicle frame. The stiffness parameters of the three-way vibration isolators are 120kN / mm in the X / Y direction and 80kN / mm in the Z direction, forming a vibration transmission path blocking structure.

[0020] Preferably, the device reduces cab noise from 82dB(A) to 68dB(A) through a triple technical approach of materials, structure, and active control, achieving a comprehensive noise reduction of 14dB(A), which meets the requirements of GB / T 3450-2018 standard.

[0021] The low-noise diesel engine compartment vibration isolation and noise reduction device for internal combustion locomotives provided by this invention has the following beneficial effects:

[0022] 1) By applying composite vibration isolation material layers, wide-band noise control is achieved, especially at 1000Hz, the sound absorption coefficient can reach more than 0.7 and the sound insulation exceeds 25dB, which effectively improves the sound environment of the cab.

[0023] 2) The vibration isolation base, composed of double-layer elastic support and metal-rubber composite vibration isolators, reduces the vibration transmission rate of the diesel engine from 30% to below 12%, significantly reducing the transmission of vibration in the structure;

[0024] 3) The acoustic covering structure of the cab combines gradient density sound-absorbing cotton with a micro-perforated plate resonant structure, which reduces noise in the 125-4000Hz frequency band by 8-15dB and improves the comfort of the cab.

[0025] 4) The Helmholtz resonant cavity array is specifically designed to attenuate low-frequency noise in the 200-800Hz range, solving the problem of low-frequency noise that is difficult to control using traditional methods.

[0026] 5) The active noise cancellation system uses the LMS algorithm to achieve real-time cancellation of low-frequency noise in the 50-500Hz range, reducing the noise level in the driver's ears by 10.3dB(A);

[0027] 6) The constraint layer damping treatment structure reduces structural sound radiation by 5dB, and the acoustic optimization design of the airflow channel shifts the peak value of the fan noise spectrum from 630Hz to over 1000Hz, thus comprehensively improving the noise reduction effect.

[0028] 7) Fully meets the requirements of the "Noise Limits for Railway Locomotives and Rolling Stock" (GB / T 3450-2018) standard, improves the working environment for drivers, and reduces the risk of hearing damage;

[0029] 8) Extending the diesel engine overhaul cycle from 80,000 kilometers to 120,000 kilometers saves an average of 48,000 yuan in maintenance costs per year, resulting in significant economic benefits. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the overall structure of the low-noise diesel engine compartment vibration isolation and noise reduction device for internal combustion locomotives according to the present invention.

[0031] Figure 2 This is a schematic diagram of the composite vibration isolation material layer of the present invention;

[0032] Figure 3 This is a schematic diagram of the installation structure of the vibration isolation base of the present invention;

[0033] Figure 4 This is a schematic diagram of the installation of the acoustic enclosure structure for the driver's cab of the present invention;

[0034] Figure 5 This is a schematic diagram of the Helmholtz resonant cavity array of the present invention;

[0035] Figure 6 This is a block diagram illustrating the control principle of the active noise reduction system of the present invention.

[0036] Figure 7 This is a schematic diagram of the installation of the constraint layer damping treatment structure of the present invention;

[0037] Figure 8 This is a schematic diagram of the optimized cooling fan structure of the present invention;

[0038] Figure 9 This is a schematic diagram of the installation position of the three-way vibration isolator of the present invention;

[0039] Figure 10 This is a frequency response curve of the noise reduction system of the present invention. Detailed Implementation

[0040] Please refer to the attached document. Figure 1-10 The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0041] like Figure 1 As shown, the low-noise diesel engine compartment vibration isolation and noise reduction device for internal combustion locomotives provided by the present invention includes a composite vibration isolation material layer 1, a vibration isolation base 2, an acoustic covering structure for the cab 3, a Helmholtz resonant cavity array 4, an active noise reduction system 5, a constraint layer damping treatment structure 6, an optimized cooling fan structure 7, and a three-way vibration isolator 8 disposed between the diesel engine and the vehicle frame.

[0042] Preferably, such as Figure 2As shown, the composite vibration isolation material layer 1 includes a surface PU wear-resistant layer 11, a middle sponge sound-absorbing layer 12, and a bottom damping adhesive 13. In one embodiment of the present invention, the thickness of the middle sponge sound-absorbing layer 12 is designed to be 3mm, and the material performance is enhanced through nanotechnology. Experimental tests show that the composite vibration isolation material layer 1 achieves a sound absorption coefficient of 0.75 at a frequency of 1000Hz (higher than the 0.5-0.6 level of conventional sound-absorbing materials), a sound insulation of 27dB, and a damping coefficient of 0.08 at a frequency of 100Hz. These parameters were selected based on acoustic testing findings that the main noise frequencies of diesel engines are concentrated in the 800-1200Hz range, and a 3mm thick sponge layer has the best sound absorption performance in this frequency band; simultaneously, the damping coefficient of 0.08 is the optimal value verified through multiple experiments, ensuring sufficient damping effect without excessively increasing the material thickness.

[0043] like Figure 3 As shown, the vibration isolation base 2 includes a double-layer elastic support 21 and a metal-rubber composite vibration isolator 22. This invention optimizes the stiffness distribution of the support points using finite element simulation technology, significantly reducing the vibration transmission rate of the diesel engine from 30% to 11.5%, lower than the design target value of 12%. In practical applications, the stiffness distribution of the support points adopts a non-uniform design, with higher support stiffness at the front end of the diesel engine (near the generator side), approximately 130 kN / mm, and lower support stiffness at the rear end (near the flywheel side), approximately 110 kN / mm. This gradient stiffness distribution better adapts to the torsional vibration characteristics of the diesel engine during operation.

[0044] like Figure 4 As shown, the acoustic enclosure structure 3 of the cab includes gradient density sound-absorbing cotton 31 and a micro-perforated plate resonant structure 32. Preferably, the density range of the gradient density sound-absorbing cotton 31 is set to 80-120 kg / m³, and this gradient density design can achieve a noise reduction of 8-15 dB in the 125-4000 Hz frequency band. Specifically, the sound-absorbing cotton with a lower density (approximately 80 kg / m³) near the noise source is beneficial for high-frequency absorption; while the density with a higher density (approximately 120 kg / m³) near the inner wall of the cab is enhanced for low-frequency absorption. Experimental data shows that in the 800-1200 Hz frequency band (the main noise frequency band of diesel engines), this structure can achieve a noise reduction effect of 12-14 dB.

[0045] like Figure 5As shown, the Helmholtz resonant cavity array 4 is disposed on the inner wall of the intake and exhaust pipes of the diesel engine compartment, specifically for attenuating the peak frequency of low-frequency noise in the 200-800Hz range. This invention employs a cascaded design of resonant cavities of different sizes, including 18 resonant cavities with diameters of 40mm, 60mm, and 80mm, corresponding to resonant frequencies of 250Hz, 500Hz, and 750Hz, respectively, forming a wideband low-frequency noise suppression effect. The relationship between the volume V of the resonant cavity and the neck area S and length L satisfies the formula: f = (c / 2π)·√(S / (V·L)), where f is the resonant frequency and c is the speed of sound (approximately 343m / s). Precise attenuation of noise at specific frequencies is achieved by adjusting these parameters.

[0046] like Figure 6 As shown, the active noise cancellation system 5 includes four error microphones 51 and eight secondary sound source speakers 52, and achieves real-time cancellation of low-frequency noise in the 50-500Hz range through the LMS (Least Mean Square) algorithm. The system adopts the FxLMS algorithm (Filter Reference Least Mean Square Algorithm), the core formula of which is:

[0047] W(n+1) = W(n) - μ·e(n)·X'(n)

[0048] Wherein, W(n) is the control filter weight vector, μ is the convergence coefficient (set to 0.001 in this system, which is the optimal value verified through multiple experiments; larger values ​​will lead to system instability, while smaller values ​​will reduce the convergence speed), e(n) is the error signal, and X'(n) is the reference signal after filtering by the secondary channel estimation model. The system sampling frequency is set to 2048Hz, and the filter order is 256, meeting the time domain resolution requirements for low-frequency noise processing in the 50-500Hz range. Experimental tests show that the system reduces noise at the driver's ear position by 10.3dB(A), with the most significant noise reduction effect at idle conditions, reaching 12.5dB(A).

[0049] like Figure 7 As shown, the constraint layer damping treatment structure 6 is installed on the vehicle floor and includes a 2mm thick high-loss factor putty 61. Preferably, the high-loss factor putty 61 has a loss factor η ≥ 0.35, which is used to reduce structural sound radiation by 5dB. The 2mm thickness is chosen based on material mechanics analysis and empirical data. A putty layer that is too thin (e.g., 1mm) will not have sufficient damping effect, while a putty layer that is too thick (e.g., 3mm or more) will increase weight without significantly improving the effect. The loss factor η is set to 0.35 to comprehensively consider the stability and damping effect under temperature changes (-40℃ to 60℃), within which the putty material properties are relatively stable.

[0050] like Figure 8As shown, the optimized cooling fan structure 7 includes seven non-equidistant blades 71 and a shroud 72, wherein the radius of curvature R of the shroud 72 is ≥150mm. This invention optimizes the cooling fan design based on fluid dynamics principles. The non-equidistant blade design (angles between adjacent blades are 48°, 53°, 50°, 55°, 49°, 52°, and 53°) effectively disperses blade frequency noise energy, shifting the peak fan noise spectrum from 630Hz to over 1000Hz. The shroud's radius of curvature is chosen to be no less than 150mm because experimental verification shows that this curvature significantly reduces vortex noise caused by airflow separation; values ​​below this value lead to a significant increase in vortex noise.

[0051] like Figure 9 As shown, 12 sets of three-way vibration isolators are installed between the diesel engine and the chassis. The stiffness parameters are designed to be 120 kN / mm in the X / Y direction and 80 kN / mm in the Z direction, forming an effective vibration transmission path blocking structure. This differentiated stiffness design is based on the analysis of the diesel engine's vibration characteristics: higher stiffness is required in the horizontal direction (X / Y direction) to limit the lateral displacement of the diesel engine, while lower stiffness is used in the vertical direction (Z direction) to achieve better vibration isolation. The vibration isolators are arranged in a "4-4-4" configuration, with four in the front, middle, and rear, optimizing overall support stability and vibration isolation effect.

[0052] This invention, through the synergistic effect of three technical pathways—materials, structure, and active control—reduces the noise level in the cab of a diesel locomotive from 82 dB(A) to 68 dB(A), achieving a comprehensive noise reduction of 14 dB(A). Figure 10 As shown in the frequency response curve, effective noise reduction is achieved across the entire frequency band, especially in the 800-2000Hz frequency band where the human ear is sensitive, where the noise reduction effect is most significant, fully meeting the requirements of GB / T 3450-2018 standard (requiring cab noise ≤75dB(A)).

[0053] This invention not only significantly improves the driver's working environment and reduces the risk of hearing damage, but also extends the overhaul cycle by reducing diesel engine wear, from the original 80,000 kilometers to 120,000 kilometers, saving an average of 48,000 yuan in maintenance costs per year, thus having significant economic and social benefits.

[0054] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A low-noise diesel engine compartment vibration isolation and noise reduction device for internal combustion locomotives, characterized in that, include: A composite vibration isolation material layer, comprising a surface PU wear-resistant layer, a middle sponge sound-absorbing layer, and a bottom damping adhesive; Vibration isolation base, the vibration isolation base comprising a double-layer elastic support and a metal-rubber composite vibration isolator; The cab acoustic enclosure structure is disposed within the cab wall panel; A Helmholtz resonant cavity array, wherein the Helmholtz resonant cavity array is disposed on the inner wall of the intake and exhaust pipes of the diesel engine compartment; as well as An active noise cancellation system, comprising multiple error microphones and multiple secondary sound source speakers.

2. The low-noise diesel engine compartment vibration isolation and noise reduction device for internal combustion locomotives according to claim 1, characterized in that, The thickness of the middle sponge sound-absorbing layer in the composite vibration isolation material layer is 3mm. The composite vibration isolation material layer is enhanced by nanotechnology, and the sound absorption coefficient reaches more than 0.7 at a frequency of 1000Hz, the sound insulation exceeds 25dB, and the damping coefficient is 0.08 (at a frequency of 100Hz).

3. The low-noise diesel engine compartment vibration isolation and noise reduction device for internal combustion locomotives according to claim 1, characterized in that, The metal-rubber composite vibration isolator in the vibration isolation base is designed to reduce the vibration transmission rate of the diesel engine from 30% to below 12%, and the stiffness distribution of the support point is optimized through finite element simulation.

4. The low-noise diesel engine compartment vibration isolation and noise reduction device for internal combustion locomotives according to claim 1, characterized in that, The acoustic covering structure of the cab includes gradient density sound-absorbing cotton and a micro-perforated plate resonant structure. The density of the gradient density sound-absorbing cotton is 80-120 kg / m³, which reduces noise in the 125-4000 Hz frequency band by 8-15 dB.

5. The low-noise diesel engine compartment vibration isolation and noise reduction device for internal combustion locomotives according to claim 1, characterized in that, The Helmholtz resonant cavity array is designed to attenuate the peak frequency of low-frequency noise in the 200-800Hz range.

6. The vibration isolation and noise reduction device for the low-noise diesel engine compartment of an internal combustion locomotive according to claim 1, characterized in that, The active noise cancellation system includes four error microphones and eight secondary sound source speakers, and uses the LMS algorithm to achieve real-time cancellation of low-frequency noise in the 50-500Hz range.

7. The low-noise diesel engine compartment vibration isolation and noise reduction device for internal combustion locomotives according to claim 1, characterized in that, It also includes a constraint layer damping treatment structure, which is installed on the vehicle floor and includes a 2mm thick high loss factor putty. The high loss factor putty has a loss factor η≥0.35 and is used to reduce the structural sound radiation by 5dB.

8. The low-noise diesel engine compartment vibration isolation and noise reduction device for internal combustion locomotives according to claim 1, characterized in that, It also includes an optimized cooling fan structure, which includes 7 non-equidistant blades and a shroud with a curvature radius R ≥ 150 mm, thereby shifting the peak value of the fan noise spectrum from 630 Hz to over 1000 Hz.

9. The low-noise diesel engine compartment vibration isolation and noise reduction device for internal combustion locomotives according to claim 1, characterized in that, Twelve sets of three-way vibration isolators are installed between the diesel engine and the vehicle frame. The stiffness parameters of the three-way vibration isolators are 120kN / mm in the X / Y direction and 80kN / mm in the Z direction, forming a vibration transmission path blocking structure.

10. The low-noise diesel engine compartment vibration isolation and noise reduction device for internal combustion locomotives according to claim 1, characterized in that, The device reduces cab noise from 82dB(A) to 68dB(A) through a triple technical approach of materials, structure, and active control, achieving a comprehensive noise reduction of 14dB(A), which meets the requirements of GB / T 3450-2018 standard.

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