RU2520701C2 - Method to measure noise produced by vehicle tyres when in motion - Google Patents

Abstract

FIELD: measurement equipment.

SUBSTANCE: 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.

EFFECT: identification of noise produced by tyres in the total noise produced by a moving vehicle.

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Description

The invention relates to the field of acoustics of motor vehicles (hereinafter referred to as automatic telephone exchanges), in particular to methods for measuring external noise of automatic telephone exchanges, and can be used to identify noise produced by tires and to determine its contribution to the overall noise level of automatic telephone exchanges.

Due to the ever-growing number of telephone exchanges, the harmful effects of traffic noise are recognized as one of the most widespread environmental problems of our time.

Currently, the world's leading manufacturers of automatic telephone exchanges are actively working to reduce noise emitted into the environment. An important component of this activity is the development of methods and methods for testing automatic telephone exchanges both at the design stage and in the production process.

It has been established that the total external noise emitted by the vehicle in the environment consists of a set of noise sources of which are the working units, mechanisms, systems of the vehicle, as well as noise arising from the movement, generated including tires and road surface. Studies have shown that in the short term, measures aimed at reducing noise through the modernization of nodes and systems of automatic telephone exchanges are expensive and ineffective, while at the same time, improvement of acoustic performance is possible due to the use of low-noise tires and qualitatively new road surfaces.

In this regard, the urgent task is to develop an economical, technologically advanced and reliable method for measuring noise, aimed at identifying and effectively assessing that part of the total noise of the telephone exchange in motion that is produced by the tires.

There are various methods and technical solutions for their implementation, aimed at solving the above problem, for example, "Device for measuring noise between the tire and the road surface" from the description of the utility model for patent CN2876737, IPC ⁶ G01H 17/00, publ. dated 08/18/2006, including a control and measuring device for use between the road surface and the tire, related to noise measuring devices. The device includes serially connected: speed data storage terminal, encoder, first sound pressure power supply and a microphone, sound conductor device, and second sound pressure power supply connected in series. The first and second sound pressure power supplies are connected to a combining drive. The speed data storage terminal is fixed on the wheel hub of the vehicle and rotates with it. The input shaft of the encoder is connected to the center of the terminal of the speed data storage device and to its output storage terminal connected to the first sound pressure power supply via a cable. One end of the connecting arm is fixed to the encoder, and the other is connected to the sound conductor apparatus, so that the microphone adjoins the tires and the base of the road surface and moves with the wheels. The device is designed to measure noise between the road surface and the tire during movement and allows to exclude the influence of other noise.

Also known is a device for measuring noise in the near acoustic field of a road tire, described in patent CN 201488808, IPC ⁶ G01H 17/00, publ. dated May 21, 2009, which contains a microphone, a data line, a data recording device, and sequentially interconnected: a wheel arch mounting plate, soundproof shields, and shockproof protection. The soundproof panel includes front, rear and side soundproof panels that are firmly bolted, the upper surfaces of the front soundproof panel and the rear soundproof panel being located in close proximity to the vehicle chassis. In this case, the curvature of the wheel arch mounting plate corresponds to the curvature of the arch of the test vehicle wheel. The wheel arch, on which the mounting plate is mounted, is firmly connected to the wall of the soundproof panel and the vehicle body by means of a bolted connection. Shockproof protection is fixed at the base of soundproof shields. The microphone mount is located on the rear soundproof side. Soundproof shields are located around the tire, forming a semi-closed circuit, while in addition to performing the function of an insulator, the shields absorb the sound generated by the vehicle, which eliminates the effect of the specified sound on the microphone and, thus, improves the accuracy of measurements.

The above-described devices make it possible to determine the rolling noise of one particular tire, but they do not allow to determine the contribution of tire noise to the external noise of the vehicle in each position on the measuring section, and, moreover, with the indicated method of installing the microphone, it is impossible to estimate the contribution of the rolling noise of all four tires simultaneously.

From the description of the patent US 2006266120, IPC ⁶ G01H 1/00, publ. 11/30/2006, the known "Method and system for determining the noise component of tires in the total noise level in the passenger compartment", which consists in installing microphones on the wheel and in the passenger compartment and determining the transfer function of noise from the wheel to the passenger compartment. This method is also impossible to apply to determine the contribution of tire rolling noise to the external noise of the vehicle in motion.

As a prototype, as the closest in the set of distinguishing features, the “Method for measuring the external noise of a Bazhenov motor vehicle” is selected, described in RF patent No. 2392603, IPC ⁶ G01M 17/007, G01M 15/00, publ. 06/20/2010, which consists in a series of noise measurements during the passage of the vehicle in acceleration mode in various gears relative to a stationary microphone, from which the maximum value is selected. Then, with an additional driveway of the PBX, external noise is recorded on the storage device in transmission and on the side of the PBX corresponding to the maximum value. After that, the characteristic frequencies of the vehicle aggregates are calculated, a spectrogram of the recorded external noise is obtained, and the calculated values of the characteristic frequencies are applied to it. Next, a second additional call of the telephone exchange is made with noise recording, the measuring microphone being installed on the telephone exchange. After that, a noise spectrogram is obtained at the second additional arrival, the calculated values of the characteristic frequencies are applied to it, the noise sources are identified and taking into account this, the sources are ranked on the first additional ATS passage.

The disadvantages of this method are the low accuracy of identification of noise sources, as well as the fact that this method does not allow to assess the contribution of noise produced by the tires to the overall level of measured noise, since the broadband noise produced by the tires does not contain pronounced discrete frequencies.

The problem to which the application of the invention is directed is to obtain a technologically advanced, reliable and economical method for identifying noise produced by tires in the general external noise of a telephone exchange in motion.

This problem is solved with technical equipment that meets the well-known requirements set forth in current regulatory documents, including GOST 41.51-99 (UNECE 51) and 31333-2006 (ISO 7188: 1994), as well as EU Directive 2001/43 / EU

The proposed method provides the following steps:

- preparation of measuring equipment and a test site with a measuring section, throughout which marks are applied at equal intervals of distances;

- a series of measurements of the noise level of a vehicle moving along a measured area in acceleration mode;

- recording by the storage device of a digital or analog type of the obtained values, including the values of the ATS speed at the positions specified by the marks;

- obtaining a diagram of values of the recorded total noise level of the telephone exchange and a graph of the values of the speed of the telephone exchange;

- determining the value of the PBX speed when crossing the microphone line;

- carrying out a series of measurements of the noise level of the vehicle, moving in coastal mode at a speed equal to the predetermined value, so that the speeds obtained when crossing the telephone exchange of the microphone line in both series of measurements coincide;

- recording of the actual values of the noise level and the values of the PBX speed in the positions specified by the marks with an analog or digital type memory device;

- obtaining a chart of recorded values of the noise level and a graph of the values of the speed of the automatic telephone exchange moving on the coast;

- identification by calculation from the total noise level of the moving vehicle, the noise produced by the tires, based on the obtained values, taking into account the distance correction, which determines the dependence of the noise level on the distance between the noise source and the sound level meter;

- Obtaining a diagram of the values of the noise level produced by the tires of a moving automatic telephone exchange at each position of the measured section specified by marks.

Features and advantages of the proposed method are illustrated by the following detailed description and illustrations, in which:

in FIG. 1 shows a diagram of a test site with a measuring section and measuring equipment, which, in particular, includes:

1 - sound level meters or equivalent noise measuring devices;

2 - speed measuring device;

3 - photo shutters;

4 - storage device digital or analog type;

5 - electronic computing device.

in FIG. 2 presents diagrams and graphs plotted based on actual values obtained as a result of measurements, including a diagram of the values of the noise level produced by tires, a moving ATS 6;

in FIG. Figure 3 presents a graph of the dependence of changes in the values of the noise level on the distance between the noise source - ATS and sound level meter - corrections for the distance L.

The implementation of the proposed method is as follows.

A test site is being prepared with a measured section, which is a horizontal rectilinear surface with a hard and even coating, the acoustic characteristics of which allow excluding the occurrence between the sound source and the microphone of interference exceeding 1 dB in a free sound field.

The measured area is indicated on the test site with lines (figure 1):

AA '- line fixing the position of the front part 7 of the moving ATS 6;

BB '- line fixing the position of the rear part 8 of the moving ATS 6;

SS '- the axial line coinciding with the longitudinal axis of the moving ATS 6;

PP '- a line on which a sound level meter 1 or an equivalent noise measurement system is installed, for example, microphones installed on both sides of a perpendicularly located SS line at a distance of 7.5 m and directed at each other at a height of from 0.9 to 1.3 m above a horizontal surface.

The total length of the measured section is 20 meters plus the overall length of the ATS 6. The lines AA 'and BB' are located 10 m respectively in front of and behind the line PP. In the interval between the lines AA 'and BB', at intervals of equal distances, marks 9 are set equally spaced from the line PP ', relative to which the position of the vehicle is determined in the measured section. In addition, for measuring the speed of a moving telephone exchange 6, a metering device 3 is installed on the measuring section. All of these instruments, via a high-speed, for example, wire 10 or wireless connection, are connected to a digital or analog type storage device 4, which, in turn, is connected to electronic computing device, for example a personal computer 5.

The first series of measurements of the total noise level of the ATS 6 is carried out, consisting of at least two passages of the ATS 6 in the measured section, in one direction, in acceleration mode, in which the ATS 6 moves in a straight line, in the direction of the measured section, thus so that the plane of the longitudinal section of the ATC 6 is as close as possible to the line CC '. At the moment when the front part 7 of the ATS 6 crosses the line AA ', the fuel pedal (not shown) is pressed fully and as quickly as possible and is held in this position until the rear part 8 of the ATS 6 crosses the line BB' , then, as soon as possible, the fuel pedal is released. At the same time, on the memory device 4 of analog or digital type, the obtained values are recorded, including the values of the ATS 6 speed at the moment the front part 7 of the moving ATS 6 intersects the set marks 9, drawn at equal intervals of distances along the entire length of the measuring section.

Based on the measurement results, a diagram 11 of the recorded total noise level of the ATS 6 (FIG. 2) and a graph of 12 values of the ATS 6 speed in acceleration mode (FIG. 2) are obtained, from which the value of the ATS 6 speed (FIG. 2) obtained when the intersection of the telephone exchange 6 microphone line PP '.

Then, a second series of measurements of the noise level of the ATS 6 is carried out, consisting of at least two passages of the ATS 6 along the measured section, in one direction in the roll-over mode, in which at the moment when the front of the ATS 6 crosses the AA 'line, the engine is switched off and the gear lever (not shown) is shifted to the neutral position. Moreover, the ATC 6 is given a speed equal to the predetermined value in such a way that the speeds of the ATC 6 (Fig. 2) obtained when the ATC 6 of the microphone line PP 'intersects, in both series of measurements, coincide. At the same time, on the memory device 4 of analog or digital type, the actual values obtained are recorded, including the speeds of 13 automatic telephone exchanges 6 at each position of the measuring section set by marks 9 (Fig. 2), after which a diagram of 14 recorded values of the automatic telephone exchange noise level is obtained 6, coasting (Fig.2.).

Of great importance for the accuracy of subsequent calculations is the completeness of coverage of the ATS 6 moving in the roll mode of the entire speed range 12 obtained after the first series of measurements of the values of the speed of the ATS 6 moving in acceleration mode.

The identification of noise produced by tires in the total noise level of a moving ATS 6 is carried out by comparing the values of 11 total noise levels of the ATS 6 obtained in acceleration mode with the values of 14 noise levels of the ATS 6 obtained in the coast mode. The result of a direct comparison of the values contains a significant error, since the same position of the ATS 6 relative to the given marks 9 corresponds to different speeds and vice versa, the correlation of the speeds does not correspond to the position of the ATS 6 relative to the microphone line PP '. To account for the arising error, the obtained values are converted using the distance correction (Fig. 3), which determines the dependence of the noise level change on the distance between the noise source — ATS 6 and sound level meter 1 and calculated by the formula:

,дБ $$\Delta =10\cdot \lg \left(\frac{{\mathrm{<figure-callout\; id="2"\; label="S"\; filenames="00000004.png,00000005.png"\; state="\{\{state\}\}">S</figure-callout>}}_2+{7.5}^2}{{7.5}^2}\right)$$

dB

where S is the distance between the noise source - ATS to the microphone line, m; 7.5 - distance from the longitudinal axis of the vehicle to the sound level meter or equivalent noise measurement system, m

Thus, the correction for the distance Δ is initially summed up with the corresponding values of the ATS 6 noise level 6 obtained during a series of measurements moving in the ATS 6 roll-up mode. Then, the noise levels adjusted in this way together with the values of the ATS moving speed in a roll-off mode , compare with the values of the speed of the ATS moving in acceleration mode, and determine the corresponding values of the noise level, from which they then subtract the correction for the distance Δ, in as a result of which, on the basis of the calculated values, a diagram 15 of the noise level produced by the tires of a moving automatic telephone exchange is obtained, at each position of the measuring section given by marks 9. The sequence of steps of the method is completed.

The advantage of the proposed method is that its use allows you to obtain reliable indicators of the noise level produced by the tires of the PBX in motion, in each position of the PBX in the measured area, with standard equipment and a minimum number of ATC rides. One example of the use of the proposed method, for example, is the rapid assessment of the acoustic characteristics of a set of tires intended for use mainly in winter conditions installed on mass-produced automatic telephone exchanges of various model modifications.

This method has been successfully tested at the design stage and in the production process of cars of AvtoVAZ OJSC.

Claims (2)

A method of measuring the noise produced by the tires of a motor vehicle in motion, in which a series of measurements of the noise level of a motor vehicle moving in a measured area is characterized in that a series of measurements of the noise level of a motor vehicle moving in a measured area in acceleration mode is carried out previously, simultaneously with this , a digital or analog type memory device records the obtained values, including the vehicle speed values in the position measurements given at equal intervals of distances along the entire length of the measured section, after which a diagram of the recorded noise level of the vehicle is obtained and the value of its speed when crossing the microphone line is determined, then a series of measurements of the noise level of the vehicle moving along the measured section is carried out with speed equal to the predetermined value in such a way that the speeds obtained when the vehicle crosses the microphone line in both The measurement series coincided, at the same time, a digital or analog type memory device records the actual values obtained, then a diagram of the recorded noise level values of the coastal vehicle is obtained, after which the noise produced by the tires in the total noise level of the moving vehicle is identified by comparison the values of the total noise level of the vehicle exchanges obtained in acceleration mode with the values of the noise level of the vehicle exchanges obtained in the coast mode with the use of distance correction, о redelyayuschey dependence of the noise level on the distance between the noise source and the sound level meter, and calculated from the formula:
$$\Delta =10\cdot \lg \left(\frac{S^2+{7.5}^2}{{7.5}^2}\right)$$

dB
where S is the distance between the noise source - the telephone exchange and the microphone line, m .; 7.5 - the distance from the longitudinal axis of the ATS to the sound level meter or equivalent noise measurement system, m,
on the basis of the calculated values, a diagram is obtained of the noise level produced by the tires of a moving vehicle in each position of the measuring section specified by marks.

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