Determination of acoustic characteristics of car cabin

IPC classes for russian patent Determination of acoustic characteristics of car cabin (RU 2513436):

G01M17/007 -

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Determination of acoustic characteristics of car cabin / 2513436

Invention relates to automotive industry, particularly, to determination of passenger cabin acoustic characteristics and can be used for acoustic development of design automobiles. Proposed method consists in measurement of noise level inside the cabin on the journey and comparison of its level with standard magnitude. In includes selection of carrier with cabin meeting the noise standards, is extra road tests wit recording of chassis noise sources, placing of selected carrier on the site and its irradiation with recorded noise from the side of cabin floor outer surface. Note here that noise level inside the cabin is measured and to obtain spectral characteristics. Thereafter, pilot cabin is irradiated with the same noise to define the quality of sound isolation of said pilot cabin.

Method to determine torsional compliance of hydromechanical transmission / 2520648

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where r_K stands for the radius of the tractor drive sprocket,

P_{K}^{O}

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Method to measure noise produced by vehicle tyres when in motion / 2520701

Invention relates to vehicle testing. A series of measurements of noise level produced by a vehicle moving in the test section in the acceleration mode is performed, obtained values are recorded, a diagram of recorded values of the vehicle noise level is developed and the vehicle velocity at crossing the microphone line is defined. A series of measurements are performed in respect to the noise level produced by a vehicle moving in the test section in the free running mode with the velocity equal to a prescribed value so that the velocities obtained at vehicle's crossing the microphone line were the same in both measurement series. The diagram of recorded noise level values of the free running vehicle is developed. The noise produced by the tyres is identified in the total noise level of the moving vehicle by comparing the total noise level values of the accelerating vehicle to the noise level values of the free running vehicle adjusted for the distance specifying the dependence of the noise level change on the distance between a noise source and a noise metre.

FIELD: transport.

SUBSTANCE: invention relates to automotive industry, particularly, to determination of passenger cabin acoustic characteristics and can be used for acoustic development of design automobiles. Proposed method consists in measurement of noise level inside the cabin on the journey and comparison of its level with standard magnitude. In includes selection of carrier with cabin meeting the noise standards, is extra road tests wit recording of chassis noise sources, placing of selected carrier on the site and its irradiation with recorded noise from the side of cabin floor outer surface. Note here that noise level inside the cabin is measured and to obtain spectral characteristics. Thereafter, pilot cabin is irradiated with the same noise to define the quality of sound isolation of said pilot cabin.

EFFECT: higher validity, lower costs.

1 dwg

The invention relates to the field of acoustics of vehicles, more particularly to a method of determining acoustic characteristics of salons vehicle, such as buses, passenger cars and commercial vehicles, and can be used to estimate the insulating properties of the floor of the cabin to minimize costs acoustic fine-tuning of the TC to the normative values for the noise level inside the cabin.

Known analogs of the present invention, such as method of measurement of sound insulation of walls (panels), described in the source: noise Control in industry: the Prevention, reduction and control of industrial noise in England: TRANS. from English. Ed. Job. - Leningrad: Sudostroenie, 1981, p.52 and RIS. Laboratory setup for measurement of sound insulation of a partition consists of two chambers - the high and the low level, the first of which has the sound sources (loudspeakers)and the other measuring microphones. In the opening between the chambers hermetically test set partition. The speaker serves a broadband electrical signal, for example, in the band 50-10000 Hz, and they begin to emit broadband noise, which, partly through the partition, enter the camera low and is registered by the measuring microphones. In the chamber of the high level of noise also Regis is eroitca microphone, in front of the wall. The value of insulation R is determined by the formula:

R=L₁-L₂+10l g (S/A), dB,

where L₁- the noise level in the chamber high level, dB;

L₂- the noise level in the chamber to the low level, dB;

S - size of the partition, m²;

And total absorption in the camera high level, m².

The design and method of measurement of sound insulation are used, as a rule, the organizations involved in the design of building structures and materials.

The disadvantages of the method are:

- the high cost of the camera, because the camera is 100-150 m, they are made of concrete with a minimum thickness of 0.5 m, and the camera installed on a separate Foundation, mechanically isolated from the Foundation of the room where there are cameras;

- asked the speakers, the noise does not correspond to the noise sources of the CU (gearboxes axles, exhaust system, gear box and so on), and the camera's low level does not reproduce the geometry, stiffness and sound absorbing characteristics of beauty, TC, and therefore the results of measurements of sound insulation, for example the floor of the cabin TC, of no particular value without carrying out more complex calculations to assess the level of noise inside the cabin and its compliance with the regulatory value is the second.

As a prototype, as the closest in essence, the selected method of measuring internal noise set forth in GOST R 51616-2000: Motor vehicle. The internal noise. Permissible levels and test methods. - M.: Publishing house of standards, 2000, p.4-5, p and 5.5, which consists in the fact that the noise inside the cabin TC measured above each row of seats, when driving the vehicle in the deceleration in top gear in the horizontal section of paved road. The speed of the vehicle is changed from some initial to some final speed corresponding to 45 and 90% of maximum engine power. For the measurement result take the maximum noise level, realizovavshaja in the tests, which compare with the standard value. The disadvantage of the prototype is that with its help get the actual values of the noise level in the cabin when road testing vehicle on which it is impossible to determine the cause, for example, exceeding the measured level is above the standard value, which introduces uncertainty into the process acoustic refinement vehicle internal noise (noise reduction), increases the terms of finishing and its cost. It should be noted that the main sources of noise, such as crew bus, located under the passenger compartment floor. These include gearboxes leading m the ists, the exhaust system, gear box, tires and other Noise inside vehicle during its movement is formed by these sources, and its level depends mainly from the insulating properties of the floor of the cabin. In this regard, the preferred option when assessing the acoustic performance of the developed pattern of the cabin, for example, crew bus, it would compare the sound insulation properties of its structural elements with similar properties design salon, meet regulatory requirements on internal noise, and data insulating properties, it would be preferable to obtain in the laboratory. This way acoustic refinement of beauty is characterized by high efficiency and effectiveness of the work and is not associated with the extensive road tests.

The problem solved by the invention is to create a method for determining the acoustic characteristics of the vehicle, which would allow us to quickly obtain data on the insulating properties of its structural elements, in particular gender, for further acoustic refinement of internal noise to the values and minimize costs.

This is achieved by the fact that in the known method for determining the acoustic characteristics of the car cf is DSTV, consisting in conducting road tests with measurement of noise inside the cabin at the given points when the vehicle is in the deceleration in top gear on a measuring site in a given range of frequency of rotation of the crankshaft of the engine of the vehicle with the subsequent comparison of the measured maximum values of the noise with the standard value according to the invention:

- choose a vehicle with a passenger cabin that meets the normative significance of noise on the results of road tests;

- conduct additional testing of the selected vehicle when it is driven in the mode of acceleration in top gear on a measuring site in a given range of frequency of rotation of the crankshaft of the engine with the record on the storage device noise characteristic of the sources located on the chassis of the vehicle opposite the outer side of the floor of the passenger compartment;

- set the selected vehicle on the ground without running the engine and placed on the surface of the platform speakers, located under each of the typical sources of noise chassis of the vehicle;

- at the same time on each of the speakers from the storage device serves the electrical signal recorded with additional test of the selected TC corresponding to the source signal noise chassis, which placed this aku the optical system;

- the level of radiated noise near the outer side of the floor of the passenger compartment in front of each of the speakers set equal to the noise level of the corresponding noise source chassis vehicle with additional test;

- measure the noise level inside the passenger compartment of the vehicle at the given points and get its spectral characteristics;

- carry out similar tests on exposure to noise, recorded with additional test of the selected vehicle, the outer surface of the floor experienced the passenger compartment of the vehicle from the measurement of noise inside his points, similar to the measurement points selected TC obtaining spectral characteristics;

- compare the levels and spectral characteristics of both salons and their difference in judging the sufficiency or insufficiency of the insulating properties of the floor of the prototype of the passenger compartment.

The essence of the invention is illustrated in figure 1, which presents the scheme of the test by the proposed method (as CU figure 1 shows, for clarity, field bus). TC contains the passenger compartment 1 is placed inside the seat 2 is fixed to the floor 3. TC mounted on the platform 4. For simplicity, figure 1 shows vehicle with the wheel formula 4×2 (leading is the rear axle). Consider the case to the da noise sources of the chassis are the exhaust system, escaping from the muffler 5, the gear drive axle 6 and the lugs of the tire 7. When driving vehicle by measuring the area of the noise generated by these sources, penetrates inside the cabin 1 through floor 3 and creates within him sound field.

Implementation of the proposed method is as follows. Let it be a vehicle, the noise level inside the cabin which according to the results of road tests, consisting in the measurement of noise inside the cabin at specified points during movement of the vehicle deceleration in top gear on a measuring site in a given range of frequency of rotation of the crankshaft of the engine with the subsequent comparison of the measured maximum level with the regulations, the standard value. Let's call it TC the selected vehicle. Measurement of noise inside the cabin during road tests conducted over the seat in the vicinity of the ear of the passenger (points M1 and M2, see figure 1).

Then conduct an additional test of the selected vehicle when it is driven in the mode of acceleration in top gear on a measuring site in a given range of frequency of rotation of the crankshaft of the engine with the record on the storage device noise characteristic of the sources located on the chassis of the vehicle opposite the outer side of the floor of the passenger compartment. Figure 1 external noise sources recorded at the point M3 (noise reducer drive axle 6 and the noise Grun is onazepam tires 7) and the point M4 (noise, exhaust gases, escaping from the muffler 5). Record noise carried out on a PC or a measuring tape with the possibility of further repeat play.

Then the selected TC mounted on the platform 4 without starting the engine and placed on the surface of the pad 4 speaker system 8 located under each of the characteristic noise sources of the vehicle. In figure 1 one of the speakers 8 is located under the gear drive axle 6 and the lugs of the tire 7, another system 8 is located under the exhaust gases flowing out of the muffler 5. Under the sound system is high quality broadband sound source, decorated in the case.

After this, each speaker systems 8 from a storage device (not shown in figure 1) serves the electrical signal recorded with additional test of the selected TC corresponding to the source signal noise chassis, which placed this speaker system, i.e. the system 8 (see figure 1)placed under the muffler 5 signal recorded at the point M4, and 8 positioned below the gear drive axle 6 and the lugs of the tire 7, the signal recorded at the point M3 with additional road tests of the selected vehicle. The level of radiated noise near the outer side of the floor 3 of the passenger compartment (in points M3 and M4) in front of each the ow of acoustic systems 8 set (using the adjust amplifier playback device) is equal to the noise level of the corresponding noise source chassis vehicle with further testing. Thus, by exposure to noise by using acoustic systems 8 model acoustic impact noise sources of the chassis on the external surface of the selected vehicle.

Then measure the noise level inside the passenger compartment of the vehicle at the given points (the points M1 and M2) when exposed to noise floor of the cabin through loudspeakers 8 and get the spectral characteristics of the measured noise, such as 1/3-octave or narrow band spectra.

Then conduct similar tests for exposure to noise, recorded with additional test of the selected vehicle, the outer surface of the floor experienced (for example, newly designed passenger compartment of the vehicle from the measurement of noise inside at points similar to the points of measurement of the internal noise of the selected TC (points M1 and M2) to obtain the same spectral characteristics. In these trials experienced salon TC settings setting the audio equipment (amplifier) must be identical to the settings when testing the selected vehicle. In addition, the chassis of the selected vehicle and experienced vehicle must be of the same type.

Then compare the levels and spectral characteristics of both salons obtained when exposure to noise through the speakers, and their difference in judging the sufficiency or insufficiency of the SV is hitlerowsa properties of the floor of the prototype of the passenger compartment. The sequence of method completed.

It should be noted that the inventive method is applicable for the evaluation of the sound insulation properties of a cab of the vehicle. In this case, the speakers should be placed under the cabin floor, and characteristics of the emitted systems noise should match the characteristics of noise sources located under the floor of the cab.

The advantage of the proposed method is the efficiency and effectiveness of the obtained measurements by which to judge the acoustic characteristics applied in the construction of the cabin materials. In addition, the application of the method significantly reduces the cost of the acoustic tuning of the TC, since the tests are performed in laboratory conditions. The inventive method was tested by the applicant on one developed by a third party passenger cabin crew bus. Tests and comparison with selected beauty TC showed low insulating properties of the structure experienced the beauty that was created inside higher compared to the normative values of the noise levels.

According to the applicant, the proposed method with new, distinctive signs, industrial applicability and positive technical result can be protected by a patent.

The way to determine the population of the acoustic characteristics of the passenger compartment of the vehicle, consisting in conducting road tests with measurement of noise inside the cabin at the given points when the vehicle is in the deceleration in top gear on a measuring site in a given range of frequency of rotation of the crankshaft of the engine of the vehicle with the subsequent comparison of the measured maximum values of the noise with the standard value, characterized in that you choose the vehicle with a passenger compartment that meets the normative significance of noise on the results of road tests, followed by additional testing of the vehicle when it is driven in the mode of acceleration in top gear on a measuring site in a given range of frequency of rotation of the crankshaft of the engine with the record on storage device noise characteristic of the sources located on the chassis of the vehicle opposite the outer side of the floor of the passenger compartment, then set the vehicle on the ground without running the engine and placed on the surface of the platform speakers, located under each of the typical sources of noise vehicle chassis, and then at the same time on each of the speakers from the storage device serves the electrical signal recorded when additional is " a test of the selected vehicle, the corresponding signal of the noise source chassis, which placed this speaker system, the level of radiated noise near the outer side of the floor of the passenger compartment in front of each of the speakers set equal to the noise level of the corresponding source chassis of the vehicle when additional test, measure the noise level inside the passenger compartment of the vehicle at the given points and get its spectral characteristics, followed by similar tests on exposure to noise, recorded with additional tests of the selected vehicle, the outer surface of the floor experienced the passenger compartment of the vehicle with the measurement of noise inside his points, similar to the measurement points selected vehicles with obtaining spectral characteristics, and then compare the levels and spectral characteristics of both salons and their difference in judging the sufficiency or insufficiency of the insulating properties of the floor of the prototype of the passenger compartment.