The quietest and quietest tires. Coursework: Features of the operation of automobile tires The noise level of the treads of automobile tires References
Regular check tire tread wear level should become a habit of every motorist. Tire tread- the only part of it that is in contact with the road surface. The quality of the tire rubber and the tread depth directly affect the vehicle's grip performance.
A worn tire is exposed to more risk of puncture and aquaplaning... Besides braking quality and road stability decrease according to the level of wear, especially in winter weather conditions.
Maximum allowable wear level is determined by Russian legislation and is equal to 1,6 mm rubber on the entire tread surface for summer car tires . For winter tires, the legal wear limit is 4 mm.
Methods for measuring tire tread wear
Wear indicator
This is the most famous system. This is a 1.6 mm thick tread block, usually located in the depth of the longitudinal grooves. If the tread is equal to the indicator level, then the tire has reached its legal life limit and therefore must be replaced. Crossing this line, the motorist commits an offense.
Photo ©: rezulteo
The classic tire wear indicator.
In order to determine location of the wear level indicator on the tire tread, find one of the following marks on the sidewall of the tire:
- TWI mark (tread wear indicator)
- Brand logo
- Triangle
Photo ©: Michelin
On tiresMichelinthe wear level indicator in the central groove is marked with a small Bibendum.
Some firms also produce intermediate tire wear indicators... Their disappearance indicates that the tire no longer provides optimum performance on wet surfaces.
Photo ©: Continental
Intermediate tire wear indicatorContinental
Digital wear indicator.
According to this method, the wear level is determined using a system of numbers located on the tire tread. The numbers indicate the depth of the rubber and wear off as the tread wears down. This method is used by many companies such as Nokian or Matador.
Photo ©: Matador
Digital tire wear indicatorMatador
Photo ©: Nokian
Digital tire wear indicatorNokian
Color change of the tire.
Two Chinese designers have created a prototype of a tire that changes color when worn. The principle is simple: when the tire is worn out, painting the inner part of the tread in a bright orange color... An unusual and interesting method, but, according to our experts, difficult to implement!
Photo ©: All Rights Reserved
Idea proposed by the agencyYanko Design
Profile depth gauge
Wear indicators are fast way assessments of the level of tread wear, but they cannot replace the accuracy obtained with the tire profile gauge... This small device, which is on sale in all car dealerships and has a fairly low cost, allows you to measure the depth of the tread grooves in various places of the car tire in accordance with the law.
Photo ©: All Rights Reserved
Professional tire tread depth gauge
In connection with the growth of technical progress in all developed countries of the world, the requirements for car tires are increasing more and more. A striking example of this is that quite recently, just less than two years ago in Europe, an important criterion in the development of tires was the impact of their chemical composition on the environment. As a result, new sanctions and regulations began to be applied to car tires, requiring additional labeling when distributed in the EU. In 2014, a new standard has become relevant, which contains the level of tire noise. It would seem a very strange innovation, but the competent persons of the European community put forward the issue of excessive noisiness for consideration. the environment.
The experts of the authoritative organization “European Federation of Transport and Environmental Protection”, who initiated this issue, stated that the noise during the movement of the car comes not only from the engine, but also from the tires. Being in constant contact with the road surface, the tire tread emits a characteristic noise, exceeding in intensity the noise from the engine already starting at a speed of 30 km / h for passenger cars, and for trucks - from a speed of 50 km / h. In addition, more intensive discussion of this issue by environmental protection authorities began in connection with the growing last years the popularity of wide-tread tires.
However, it is interesting that, along with competent organizations, consumers themselves have recently become concerned with the issue of tire noise. This is evidenced by the increasingly frequent questions on the Internet about the noise level emitted by certain tires. In this regard, we decided to devote this article to this topic.
The intensity of the noise emitted by the tires is different for different models tires, and depends on some factors. First, tire noise depends on the tread pattern itself. In the case where the tread segments have a significant number of cuts, and are located on the contact patch with the road one after the other without scatter, the superposition and increase in the frequency of sound waves leads to a significant increase in the noise level. That is why most manufacturers are faced with the need to change the order of the tread segments. In this regard, tread elements have been developed with smoother pattern lines to avoid sharp corners.
Secondly, the noise of the tire directly depends on the composition rubber compound from which this or that wheel is made. Accordingly, the higher the filling of the rubber compound with rubber, the better tire fills the roughness of the pavement, and then the depth of penetration depends on the grip. And the better the manufacturer manages to seal the contact patch, the less air gets into it, and the less air, the quieter.
Also, strong turbulences of air masses can be traced on the outer edge of the wheel, in the shoulder area. The sidewalls of "quiet" tires are equipped with special "noise dampers". Most often they look like ribbed stripes on the sidewall of the tire. Their task is to become a sound barrier between the protector and wheel rim and dampen the propagating vibration going from the tire surface to the suspension and further into the car interior.
Of course, the road surface itself strongly affects the noise level. Accordingly, whatever the car owner chooses tires, even with the lowest noise figure, the desired effect will still not be achieved on a rough surface. The better and smoother the surface on the roadway, the quieter the car will behave while moving along this road.
In addition to all of the above, do not forget about maintaining the air pressure in the tires. When the tire pressure is below normal, the contact patch area increases and, accordingly, a larger number of tread segments are simultaneously in contact with the road surface, which also entails an increase in noise. However, it is not worth pumping the tires too much, because during a long drive, the tires undergo significant deformation and heating, so this can lead to undesirable consequences, often catastrophic.
CONTENT
Introduction
1 Noise measurement methods
1.1 Vehicle noise and interactions
- tires with road
1.3. Tire noise test
2 Exploring the problem
2.1. Measures to reduce the discomfort caused by
noise
2.2. Durability, wear resistance and imbalance of tires
2.3 Results and consequences of tire / road contact noise reduction
Conclusion
Literature
Applications
- Introduction
Noise from road traffic is the cumulative result:
- the noise of a running vehicle engine,
noise from the contact of tires and the surface of the road surface.
- vehicle manufacturers,
tire manufacturers,
road builders,
oil industry (producers of road bitumen and fuel).
- Expanding cooperation between tire and vehicle manufacturers to provide more integrated approach in work to reduce traffic noise
Harmonization of various noise measurement methods on a European scale.
A complex approach- the use of methods that allow considering objects and phenomena in mutual connection and in combinations to obtain a more accurate and correct idea of the problem.
The task of the new integrated approach is the preparation of technical standards and unified legislative acts on:
- modern methods of determining the noise caused by the interaction of the road surface and the tire, as well as, the vehicle.
the rules addressed to the respective participants
recommendations for the use of appropriate types of pavement, such as porous asphalt concrete, that could contribute to the reduction of traffic noise.
- Noise level measurement methods.
The interaction of the tire and the road produces noise that is perceived to varying degrees inside and outside the vehicle.
From an environmental point of view, the noise outside the car is of interest, which can be determined by:
- measuring the overall noise figure
measuring the noise from the movement of an individual vehicle.
There are several basic methods for measuring vehicle noise, but none of these methods has yet been standardized.
Vehicle manufacturers measure overall acceleration noise levels through a variety of tests.
Engine noise measurements are essential for vehicle type approval, as the European standard requires for the approval of automotive products in the European market and the fierce competition in the industry.
Tire manufacturers measure tire-to-road noise for their own purposes, checking the overall performance of the tire under various conditions.
Road builders determine the acoustic properties of pavement surfaces, but with their own methods, which do not give comparable results, which could be linked to the noise generated by a moving vehicle (taking into account the type of tire and the operation of the engines).
Thus, within these three groups, the results expressed in physical units - decibels (dB) - cannot be used in one general mathematical model that could form the basis of decision-making.
- Vehicle noise and tire interaction with the road.
In fact, this common noise can be decomposed between two main sources:
- tractive energy of the vehicle (engine, propeller shaft, gear drives),
contact of the tire and coating.
However, if the total vehicle noise is determined by standardized methods, then there is no standard that is suitable for measuring tire-to-road contact noise as part of the total noise.
The contact between the moving tire and the surface produces a whole spectrum of sound waves, more or less perceptible, due to the rolling effect of the wheel. Knowing the mechanism of the origin and propagation of these sound waves allows you to reduce the degree of their impact on the environment.
Special noise measurement methods have been developed for the tire-car-coating combination.
The constituent noise sources were identified and the influence of each of them on various parameters involved in the generation and propagation of noise was studied.
Reducing the level of rolling noise consists in controlling the processes of its generation, propagation and absorption, which depend on:
- from the vehicle (weight, number of wheels, vibration, body shape),
from the tire (pressure / air distribution under the tread surface, its pattern, contact area and adhesion of the tire surface to the road surface),
rolling condition (speed, torque, ambient temperature),
from the road (surface characteristics of the pavement, pavement structure, cross-section).
- increases significantly with increasing speed (3 dB + 0.2 / 0.5 dB for every 15 km / h),
when driving at a constant speed of about 60 km / h, rolling noise prevails over engine noise,
when measured at the edge of the pavement varies from 3 dB depending on whether you are using smooth tires or medium (European types) tread tires,
when measured on a tire surface, noise varies from 6 dB depending on the design characteristics of the road (measured on typical European main roads).
- Tire design
Tires are subdivided:
- depending on the frame design - into diagonal and radial;
- by the method of sealing the internal volume - into chamber and tubeless;
- by applicability - for cars, off-road (for jeeps) and trucks;
- according to the type of road surface - for highway (road), universal and off-road;
- according to seasonality of use - for summer, winter and all-season;
- by the type of treadmill pattern - directed, non-directional and asymmetric;
- along the profile of the cross-section - into full-profile and low-profile.
Fig. 1. Tire device
The main parts and details of the tire:
1. protector
2.shoulder area
3.sidewall
4.breaker
5.frame
6.board
The quality of the cord largely determines the life and performance of the tire. The cords of the carcass must have high resistance to repeated deformations, tensile and impact strength, high heat resistance.
A breaker is the part of a tire that consists of ply ply and is located between the carcass and the tread of the tire. It serves to improve the bonds of the carcass with the tread, prevents its delamination under the influence of external and centrifugal forces, absorbs shock loads and increases the carcass's resistance to mechanical damage. The belt cord is located under the tread. Typically, the belt has an even number of layers, the threads of which are located at the opposite angle. Steel cord (STEEL) is most often used in the belt breaker for radial tires, since it is practically inextensible and has high strength. These properties are necessary to create a rigid belt that allows the treadmill to be nearly flat. This significantly increases the contact area with the road and increases the lateral stability of the tire.
Often one or two additional "shielding" layers of textile cord are laid on top of the metal breaker of high-speed tires, the warp threads of which are perpendicular to the carcass threads. They additionally encircle the frame and protect the metal breaker from mechanical damage. To understand what the breaker consists of (for each particular tire), you need to pay attention to what follows the inscription "TREAD", which is indicated on the sidewall of the tire, but do not forget to subtract the carcass, since it also passes under the protector.
Bead - the rigid part of the tire, which serves for its fastening and sealing (in the case of tubeless) on the wheel rim. The basis of the bead is an inextensible bead ring, woven of steel rubberized wire. The bead consists of a carcass ply wrapped around a wire ring and a round or profiled rubber filler cord. The steel ring gives the board the necessary rigidity and strength, and the filler cord gives solidity and elastic transition from the rigid ring to the rubber of the sidewall. On the outside of the bead there is a bead tape made of rubberized fabric, or cord, which protects the bead from abrasion on the rim and damage during installation and disassembly.
1.3. Tire noise test
The movement of a car on the roadway is never silent, which is due to the simplest laws of physics. Despite the fact that summer tires, in comparison with winter tires, create less noise when the car wheels touch the road surface, they nevertheless provide an unpleasant sound background. Therefore, today, along with the efficiency parameters of resistance to aquaplaning and braking on a wet road, the noise factor is of particular importance for consumers when choosing tires. Of course, the noise level of tires is also largely determined by the surface on which the movement is carried out, as well as by the pressure in the rubber. If the road surface is uneven or the tire pressure level is less than recommended, then it is obvious that the noise will increase significantly. However, much depends on the composition of the rubber compound, the tread pattern and the width of the tires. In particular, tires made with soft rubber compounds and having a relatively small contact patch with the road surface are much less noisy. The reduced noise level ensures a smoother ride and makes driving more comfortable for the driver.
Despite the growing demand from consumers to reduce the noise produced by tires, tire manufacturers are stepping up their work in this direction for another reason. The fact is that many environmental organizations and individual states in recent years have seriously attended to the problem of excessive noise on highways. For example, the European Federation for Transport and Environment has asked EU officials what can be done to reduce road traffic noise. According to this authoritative organization, much of the noise on roadways does not come from the car's engine, but from the rubber that constantly contacts the road surface. Even at speeds above 30 km / h for passenger cars and 50 km / h for trucks, the noise from the tires exceeds the noise from their engines. Considering that the demand for wide tires has been increasing in recent years, this problem is becoming more and more urgent. That is why it is expected that the new regulations of the European Commission, which should come into force on November 1, 2011, in addition to the requirements for grip on wet surfaces and tire markings will contain standards for noise levels. This state of affairs is forcing global tire manufacturers to develop new tire models with reduced noise levels.
How can you reduce the noise level of a tire when it hits the road surface? The noise level is influenced by such tire parameters as tread pattern, the design of the studs and sipes, and the characteristics of the rubber compound. Each time an individual tread block collides with the road surface, noise of a certain frequency is generated, and if all blocks are of the same size, then noise of the same frequency will be generated, which, in turn, leads to an increase in the overall noise level. Therefore, many manufacturers use blocks of different sizes in certain parts of the tread, which distributes tire noise over a wider frequency range. Such design features of tires can reduce the overall noise level.
Special tire tests help to determine the noise level and, accordingly, the driving comfort. They are usually performed in conjunction with wet and dry braking, aquaplaning resistance and other tests. The measurement of the noise produced by the tire is defined in decibels, to the right and left of the vehicle in motion. This also records the vehicle speed.
Experts from the reputable magazine "Za Rulem" carried out tests of summer tires of dimensions 205/55 R16. In traditional rubber tests, in addition to tests for handling a car on dry and wet asphalt, directional stability on a straight line, fuel consumption and ride smoothness, tests were also carried out on the noise level of summer tires. Eleven summer tires participated in the tests: Pirelli P7, Michelin Energy Saver, Nokian Hakka H, Yokohama C. Drive AC01, Maxxis Victra MA-Z1, Goodyear Excellence, Kumho Ecsta HM, Bridgestone Potenza RE001 Adrenalin, Continental ContiPremiumContact 2, Toyo Proxes CF-1 and Vredestein Sportrac 3. The magazine's experts evaluated the tire noise level, like other indicators, on a ten-point system.
The South Korean Kumho Ecsta HM tires received the lowest score in noise tests - only six out of ten. Such a low score is due to the fact that in the tests the tires showed a very serious general hum, the howling of the tread at speeds up to 80 km / h, although it practically disappears at a higher speed. Having taken the last, eleventh place in terms of noise level, summer tires Kumho Ecsta HM, nevertheless, in terms of the totality of all parameters, were able to bypass some competitors and take the overall eighth place.
Tests show that the summer tires that perform best in these important characteristics such as handling on wet and dry surfaces, aquaplaning resistance and road holding properties can be characterized by increased noise levels (Vredestein Sportrac 3). While, tires with not the most best performance for handling and braking, it can earn the highest noise ratings (Goodyear Excellence). This tells us that when choosing summer tires, it is necessary to focus not on one specific characteristic, but on a whole set of indicators, including the behavior of the tire on wet and dry road surfaces, directional stability, resistance to aquaplaning, the level of acoustic comfort and ride smoothness.
- Examining the problem
A working group of the International Road Federation conducted research and fact-finding, producing a survey entitled “Interaction between road, tires and vehicles” in four areas of relevance to environmental noise:
- Motor vehicles
Tires
Car roads
Oil industry
- methodology
compatibility of measurement results of noise levels
political assessment
Definition:
Emission - emission, radiation, emissions of waste, side effects or pollutants into the surrounding atmosphere.
- Measures to reduce the discomfort caused by noise:
a. technologies
- vehicles
trailers
tires
road surface
road design (noise barriers, tunnels, bridges, excavations ...)
- implementation of a global and comprehensive approach to the problem through international bodies (Commission of the European Union, various directorates of the DG, working groups from representatives of various industries)
informative cooperation within the framework of international bodies (International Road Federation)
solutions at the national, regional, municipal level
Track Test Standardization
An equal and reliable interpretation of test results can only be achieved if all vehicle tests are carried out on the same or equivalent test tracks. Therefore, test tracks should be standardized.
Elimination of the discomfort caused by traffic noise cannot be achieved by considering only the vehicles.
- Durability, wear resistance and imbalance of tires
The wear resistance of the tread is determined by the intensity of the tread wear, i.e. wear, referred to a unit of mileage (usually 1 thousand km), under certain road and climatic conditions and modes of movement (load, speed, acceleration). The intensity of wear Y is usually expressed by the ratio of the decrease in the height A (in mm) of the projections of the tread pattern for the run to this run Y = h / S, where S is the run, thousand km.
The durability of the tread depends on the same factors as the durability of the tire. Wheel imbalance and runout increase vibration and make it difficult to drive, reduce the life of tires, shock absorbers, steering, increase maintenance costs, worsen safety; movement. The influence of imbalance and wheel runout increases with an increase in vehicle speed. The tire has a significant effect on the total unbalance of the car, since it is farthest from the center of rotation, has a large mass and a complex structure.
The main factors influencing the imbalance and runout of the tire include: uneven wear of the tread throughout the thickness and non-uniform distribution of material around the circumference of the tire. Research carried out in NAMI shows that the most unpleasant consequences of imbalance and runout of wheels with assembled tires are vibrations of wheels, cab, frame and other parts of the car. These fluctuations, reaching the limit value, become unpleasant for the driver, reduce comfort, stability, vehicle handling, and increase tire wear.
2.3 Results and consequences of tire / road contact noise reduction:
The method has been applied to a range of surfaces including concrete, grass, porous asphalt and bitumen.
The results obtained (with an allowable error of 10%) made it possible to rank the surfaces of the road surface and evaluate their influence on the propagation of the noise of the pavement / tire contact.
For four typical surfaces, the sound absorption coefficient ranking is as follows:
etc.................
In connection with the next rules that came into force in the European Union in November 2012, each tire sold must have a label indicating three main indicators: the degree of adhesion to wet and dry road surfaces, fuel consumption and noise level. Many domestic tire manufacturers followed this example and also these parameters, on the basis of which the consumer determines his preference for a particular brand and, accordingly, a model of car tires.
Noise levels
Noise level automotive rubber on the label it is indicated in the form of a pictogram, which consists of three waves.
A noise level of 3 decibels means that a bus that makes 3 decibels more than another is twice as noisy. Whence it follows that rubber marked with three waves is at least four times louder than rubber marked with one wave.
The noise of car tires largely depends on the type of road surface and its roughness, level, as well as on the composition of the rubber compound and the width of the wheel.
Tires made using soft rubber compounds and having a relatively small area of contact with the roadway are much less noisy.
The noise level is significantly influenced by the design of the lamellas and the presence of spikes. When an individual tread block collides with the road surface, sounds (noises) of a certain frequency are generated. If these blocks are all the same size, sound is produced at the same frequency, which raises the background, increasing the overall amplitude of the sound waves. Therefore, manufacturers create tire designs in such a way that the tread blocks are different sizes, expanding the range of sound frequencies when the rubber touches the road and the overall noise level becomes much lower.
Which rubber is softer and quieter
Undoubtedly much quieter than winter ones. This is due to the tread height and the composition (including), which is much softer due to temperature regime use. show intermediate (average) results.
The noise level is determined in parallel with other characteristics of car tires on special tests. Measurements take place on speed 80 km / h. The sound level from tires varies from 74 dB. up to 82 dB. Such a large interval is associated with the type of tires (winter or summer) and other indicators, be it the tread pattern, the type of rubber compound, the area of contact with the roadway, the level of air pressure in the wheels. First of all, these tests are carried out on special stands, and then the tires are tested in real road conditions.
At the beginning of 2014, at the Pirelli training ground in Italy, the tires of the world's major manufacturers were tested, according to which the winner in all respects was the rubber:
In terms of noise level, these tires took the second place, sharing it with Pirelli p zero, Barum Bravuris 3HM, Kumho Solus HS51... Third place went to Dunlop Sport Maxx RT and Hankook Ventus S1 evo 2.
The winner in terms of noise was the wheels of the Finnish manufacturer Nokian, model:
Line XL (quietest and quietest tires)
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V overall ranking these tires only ranked sixth. Outsiders in terms of noise level were Goodyear eagle f1 and Bridgestone Potenza S001, while taking the 4th and 5th places in the overall rating, respectively.
Thus, the prizes in the "noise level" nomination were distributed as follows:
- Pirelli, Barum, Kumho.
- Dunlop, Hankook.
The average price for a set of tires among all sizes is:
- Nokian - 26,000 rubles;
- Pirelli - 50,000 rubles;
- Barum - 20,000 rubles;
- Kumho - 26,500 rubles;
- Dunlop - 28,000 rubles;
- Hankook - 36,000 rubles.
It is worth noting that the noise level is far from the most important and essential parameter for choosing tires for a car. The main ones are still other properties, such as braking, handling, aquaplaning, grip. The noise of rubber is one of the last, albeit important characteristics, and it is desirable that this indicator be optimal, with a maximum of "two waves", which is quite enough for comfortable movement.
The video presents new Winter tires from Nokian with silent sidewall technology.
As one race car driver put it, "The only car in the world that doesn't need additional soundproofing is the Rolls-Royce. Everyone else needs it." Therefore, no matter how we try to choose tires with minimum level noise, if the car is unsatisfactory, it will not solve much.
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FEDERAL AGENCY |
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NATIONAL |
GOST R (ISO 13325: 2003) |
MEASURING TIRE NOISE
ROAD SURFACE
WHEN RUNNING
Information about the standard
1. PREPARED by the Open Joint Stock Company Scientific Research Center for Control and Diagnostics of Technical Systems (JSC NIC KD) on the basis of its own authentic translation of the standard specified in clause 4
2. INTRODUCED by the Technical Committee for Standardization TK 358 "Acoustics"
3. APPROVED AND PUT INTO EFFECT by the Order of the Federal Agency for Technical Regulation and Metrology dated December 25, 2007 No. 404-st
4. This standard is modified in relation to the international standard ISO 13325: 2003 “Tires. Measurement of tire-road noise emissions by coasting "(ISO 13325: 2003" Tires - Coast-by methods for measurement of tire-to-road sound emission ") by introducing technical deviations explained in the introduction to this standard.
Introduction
This standard has the following differences from the international standard ISO 13325: 2003 applied in it:
In accordance with the requirements of GOST R 1.5-2004, international standards not accepted as national standards are excluded from the section "Normative references" Russian Federation... The section is supplemented by the following national and interstate standards: GOST 17187-81 (instead of IEC 60651: 2001), GOST 17697-72 (instead of the one specified in the structural element "Bibliography" ISO 4209-1), GOST R 52051-2003 (instead of the one specified in the structural element "Bibliography" ISO 3833), GOST R 41.30-99 (instead of ISO 4223-1), GOST R 41.51-2004 (instead of ISO 10844);
Information on the timing of the verification of measuring devices is excluded from subsection 6.1, since the frequency of verification is established by the standards of the State System for Ensuring the Uniformity of Measurements. The last paragraph is excluded from the same subsection as it repeats the test site requirements set out in clause 5;
The last phrase from A.1.7 (Appendix A) has been deleted. This phrase has been added as a note at the end of A.1.9, at the place of the first reference to the reference speed;
From the last paragraph A.2.3 (Appendix A) the phrase “This gives the desired value of the sound level L R»As duplicating the first phrase of the first paragraph of the specified paragraph;
Date of introduction - 2008-07-01
1 area of use
This standard specifies methods for measuring the noise produced by tires when interacting with the road surface when they are installed on a coasting vehicle (hereinafter - TS) or towed trailer, i.e. when the trailer or TS rolls freely with the engine, transmission and all auxiliary systems not required to operate TS... Insofar as noise when tested by the method using TS more tire self-noise, the trailer test method can be expected to provide an objective assessment of the tire self-noise.
This standard applies to cars and trucks TS as they are defined in GOST R 52051... The standard is not intended to be defined as the proportion of tire noise to total noise. TS moving under the action of engine thrust and the noise level of the traffic flow at a given point in the terrain.
2. Normative references
This standard uses normative references to the following standards:
GOST R 41.30-99 (UNECE Regulation No. 30) Uniform provisions concerning the approval of tires for motor vehicles and their trailers
GOST R 41.51-2004 (UNECE Regulation No. 51) Uniform provisions concerning the certification of vehicles with at least four wheels in relation to the noise they produce
GOST R 52051-2003 Power-driven vehicles and trailers. Classification and definitions
GOST 17187-81 Sound level meters. General technical requirements and test methods (IEC 61672-1: 2002 "Electroacoustics. Sound level meters. Part 1. Requirements", NEQ)
GOST 17697-72 Automobiles. Wheel rolling. Terms and Definitions
Note - When using this standard, it is advisable to check the validity of the referenced standards according to the index "National standards", compiled as of January 1 of the current year, and according to the corresponding information signs published in the current year. If the reference standard is replaced (changed), then when using this standard, the replacement (modified) standard should be followed. If the reference standard is canceled without replacement, then the provision in which the reference to it is given applies to the extent not affecting this reference.
3. Terms and definitions
This standard uses terms related to GOST R 41.30 and GOST 17697, as well as the following designations and terms with the corresponding definitions.
3.1. Bus classes
C1. Passenger tires TS.
C2. Truck tires TS with LI in single-digit format not exceeding 121 and speed category N or higher.
C3. Truck tires TS with LI in single-digit format not exceeding 121 and speed category M or lower, or buses with LI in single-digit format not less than 122.
3.2 bearing capacity index LI ( load index): Numeric code characterizing the maximum load that the tire can withstand under the tire manufacturer's specified operating conditions at driving speed TS corresponding to the bus speed category.
NOTE - If LI consists of two numbers, only the first number is referred to. For tires whose load capacity index is not known, the maximum load rating indicated on the sidewall of the tire is referred to.
4. General provisions
The methods specified in this standard are based on the use of a moving TS(see Appendix A) or a towed trailer (see Appendix B). Tire noise measurements are taken while driving. TS or coasting trailer.
The measurement results correspond to the objective value of the sound level emitted under the specified test conditions.
5. Test site (polygon)
The test site should be flat and horizontal. Conditions spreading sound between the sound source and the microphone should be suitable for free sound field conditions above a sound-reflecting plane with an indicator of acoustic conditions not more than 1 dB. This condition is considered to be met if there are no sound reflecting objects such as fences, barriers, bridges or buildings within 50 m of the center of the test site.
The surface of the test site should be dry and clean in all directions. The pores should also be dry. The test site and its surface must meet the requirements Appendix I GOST R 41.51(see figure 1).
6. Measuring instruments
6.1. Acoustic measuring instruments
The sound level meter must meet the requirements for sound level meters of the 1st accuracy class according to GOST 17187.
Measurements should be made using the frequency response A and timing F.
Before and after measurements, in accordance with the manufacturer's instructions or using a standard sound source (for example, a pistonphone), the sound level meter is calibrated, the result of which is entered into the measurement protocol. The calibrator must comply with class 1.
If the sound level meter reading obtained during calibration differs by more than 0.5 dB in the measurement series, results tests should be invalidated. Any deviations should be recorded in the test report.
Windscreens are used as recommended by the microphone manufacturer.
1 - trajectory of movement; 2 - microphone position; A - A, V - V, E - E, F - F- reference lines
Note - The movement of the vehicle occurs as prescribed in Appendix A, the trailer - in accordance with Appendix B.
Figure 1 - Test site and its surface
6.2. Microphones
The test uses two microphones, one on each side. TS/ trailer. In the immediate vicinity of the microphones, there should be no obstacles affecting the acoustic field and no people between the microphone and the sound source. The observer or observers should position themselves so as not to interfere with the sound measurement results. The distances between the positions of the microphones and the center line of movement on the test site should be equal to (7.5 ± 0.05) m. TS Along the centerline of travel, as shown in Figure 1, each microphone should be positioned 1.2 m ± 0.02 m above the surface of the test site and should be oriented as recommended by the manufacturer of the sound level meter for free field conditions.
6.3. Temperature measurements
6.3.1. General Provisions
Means for measuring the temperature of the air and the surface of the test track must have the same accuracy of at least ± 1 ° C. Do not use infrared thermometers to measure air temperature.
The type of temperature sensor should be specified in the test report.
Continuous recording via analog output can be applied. If this is not possible, then discrete values are determined temperature.
Measurements of the air and surface temperature of the test site are mandatory and must be carried out in accordance with the instructions of the measuring instrument manufacturers. Measurement results are rounded to the nearest whole number of degrees Celsius.
Temperature measurements should be exactly timed to sound measurements. In both test methods (with TS and trailer) as alternative option the average of the set of results can be used temperature measurements at the beginning and end of the tests.
6.3.2. Air temperature
The temperature sensor is located in a free area near the microphone so that it can sense air currents, but is protected from direct sunlight. The latter requirement is provided by any shading screen or other similar device. In order to minimize the effect of surface thermal radiation on weak air flows, the temperature sensor is placed at a height of 1.0 to 1.5 m above the surface of the test site.
6.3.3. Test site surface temperature
The temperature sensor is located in a location where it does not interfere with the sound measurements and its readings correspond to the temperature of the wheel tracks.
If a device is used in contact with the temperature sensor, then a reliable thermal contact between the device and the sensor is obtained using a heat-conducting paste.
If an infrared thermometer (pyrometer) is used, then the height surface temperature sensor chosen so as to obtain a spot with a diameter of at least 0.1 m.
It is not allowed to artificially cool the surface of the test site before or during testing.
6.4. Wind speed measurements
The wind speed measuring instrument must provide measurement results with an error not exceeding± 1 m / s. Wind speed measurements are taken at microphone height between lines A - A and V - V no further than 20 m from the center line of movement (see Figure 1). The direction of the wind relative to the direction of travel is recorded in the test report.
6.5. Travel speed measurements
The vehicle speed measuring instrument must provide the results of measuring the speed of the vehicle or trailer with an error of no more than ± 1 km / h.
7. Meteorological conditions and background noise
7.1. Weather conditions
Measurements are not carried out in unfavorable weather conditions, including gusts of wind. The tests are not carried out if the wind speed exceeds 5 m / s. Measurements are not made if the temperature of the air or surface of the test site is below 5 ° C or the air temperature is above 40 ° C.
7.2. Temperature correction
Temperature correction is only applicable for Class C1 and C2 tires. Each measured sound level L m, dBA, corrected by the formula
L = L m + K D T,
where L- corrected sound level, dBA;
K- coefficient that:
For tires of class C1 it is equal to minus 0.03 dBA / ° С when the measured surface temperature of the test site is more than 20 ° C, and minus 0.06 dBA / ° С when the measured surface temperature of the test site is less than 20 ° C;
For tires of class C2 it is equal to minus 0.02 dBA / ° С;
D T- difference between the reference value of the surface temperature of the test site of 20 ° C and the temperature of the same surface t during sound measurement, ° C
D T = (20 - t).
7.3. Background noise sound level
The sound level of background noise (including wind noise) must be at least 10 dBA lower than the measured sound level resulting from the interaction of tires with the road surface. The microphone may be provided with a windscreen, the effect of which on the sensitivity and pick-up characteristics of the microphone is known.
8. Preparation of tires and accessories
The tires to be tested must be fitted to a rim recommended by the tire manufacturer. The rim width must be specified in the test report.
Tires for the installation of which special requirements are imposed (hereinafter referred to as special tires), having, for example, an asymmetric or directional pattern protector, must be installed in accordance with the specified requirements.
Tires and rims assembled into a wheel must be balanced. Tires must be run-in before testing. The break-in must be equivalent to a 100-kilometer run. Special tires must be run in according to the same requirements.
Regardless of tread wear due to run-in, tires must have full tread depth.
Tires of classes C1 and C2 must be warmed up immediately before testing in conditions equivalent to driving at a speed of 100 km / h for 10 minutes.
Appendix A
(required)
Vehicle method
A.1. General Provisions
A.1.1. Test vehicle
Test motor TS shall have two axles with two test tires on each axle. TS shall be loaded to create a load on the tires in accordance with the requirements of A.1.4.
A.1.2. Wheelbase
The wheelbase between the two axles of the test TS must be:
a) not more than 3.5 m for tires of class C1 and
b) not more than 5.0 m for tires of classes C2 and C3.
A.1.3. Measures to minimize impact TS for measurements
a) Requirements
1) Do not use splash guards or other splash guards.
2) In the immediate vicinity of tires and wheel rims, it is not allowed to install or store elements that can shield sound radiation.
3) Wheel alignment (toe, camber and caster) must be checked empty TS and must fully comply with the manufacturer's recommendations TS.
4) Do not install additional sound-absorbing materials in the wheel arches and on the lower part of the body TS.
5) Windows and skylight TS must be closed during testing.
1) Elements TS the noise of which may be part of the background noise must be changed or removed. All taken from TS elements and design changes should be specified in the test report.
2) During the tests, it is necessary to ensure that the brakes do not generate the characteristic noise due to incomplete release of the brake pads.
3) Do not use four-wheel drive cars TS and trucks with reduction gears on the axles.
4) The condition of the suspension must be such that it prevents an excessive decrease in the clearance of the loaded in accordance with the test requirements TS... Body level control system TS relative to the road surface (if any) must provide the same ground clearance during tests as when empty TS.
5) Before testing TS must be thoroughly cleaned of dirt, soil or sound-absorbing materials that have unintentionally adhered during running in.
must satisfy the following conditions.a) The average load on all tires shall be (75 ± 5)% LI.
b) There must be no tires loaded with less than 70% or more than 90% LI.
A.1.5. Tire pressure
Each tire must be inflated to the pressure (cold tires):
where P t- pressure in the tested tire, kPa;
Rr- nominal pressure, which:
For a standard C1 bus is 250 kPa and
For a reinforced (reinforced) tire of class C1 it is equal to 290 kPa, and for tires of both classes the minimum pressure during tests shall be P t= 150 kPa;
For tires of classes C2 and C3 it is indicated on the sidewall of the tire;
Q r
A.1.6. Vehicle movement mode
Test TS should be approaching the line A - A or V - B with the engine off and with the transmission in neutral, following the "center line" trajectory as accurately as possible, as shown in Figure 1.
A.1.7. Speed range
Test speed TS at the moment the microphone passes through, it should be:
a) from 70 to 90 km / h for tires of classes C1 and C2 and
b) 60 to 80 km / h for class C3 tires.
A.1.8. Sound level registration
Record the maximum sound levels when passing the test TS between the lines A - A and V- 6 in both directions.
Measurements shall be invalidated if an excessively large difference between the maximum and total sound levels is recorded, provided that such a maximum is not reproduced in subsequent measurements at the same speed.
NOTE At certain speeds, some classes of tires may have maxima ("resonances") in sound level.
A.1.9. Number of measurements
On each side TS carry out at least four measurements of the sound level at the speed of the test TS above the reference speed (see A.2.2) and at least four measurements at the speed of the test TS below the reference speed. Test speed TS must lie within the speed range specified in A.1.7 and must differ from reference speed by approximately equal values.
Note - Reference speeds are given in A.2.2.
Measure 1/3-octave noise spectra. The averaging time must correspond to time characteristic of sound level meter F... Noise spectra should be recorded at the moment when the sound level of the transmitted TS reaches a maximum.
A.2. Data processing
A.2.1. Temperature correction
A.2.2. Reference speeds
To normalize noise relative to speed, use the following reference speed values v ref:
80 km / h for C1 or C2 class tires and
70 km / h for C3 tires.
A.2.3. Standardization relative to speed
The desired test result is the sound level L R- is obtained by calculating the regression line with respect to all pairs of measured values (velocities v i temperature-corrected sound level L i) according to the formula
L r = ` L - a `v,
where ` L is the arithmetic mean of the temperature-corrected sound levels, dBA;
Where is the number of terms NS? 16 using the measurements taken for both microphones for a given regression line;
average speed where
a- slope of the regression line, dBA per decade of speed,
Additional sound level L v for arbitrary speed v (from the considered interval of speeds) can be determined by the formula
A.3. Test report
The test report must contain the following information:
b) meteorological conditions, including air and test path surface temperatures for each pass;
c) the date and method of checking the conformity of the test area surface with the requirements of GOST R 41.51;
d) the width of the rim of the wheel under test;
e) tire data, including manufacturer's name, trade name, size, LI or load capacity, speed category, pressure rating and tire serial number;
f) manufacturer's name and type (group) of test TS, model year TS and information about any modifications ( design changes) TS regarding sound;
g) tire load in kilograms and percentage LI for each test tire;
h) air pressure in cold tire for each tire tested in kilopascals (kPa);
i) speed of passage of the test TS past the microphone;
j) maximum sound levels for each microphone on each pass;
k) maximum sound level, dBA normalized to the reference speed and temperature corrected, expressed to one decimal place.
Tables A.1, A.2 and A.3 show respectively the forms of presentation of the necessary information for the test report, data on the test conditions of the method as using TS, and using a trailer, and test results TS.
Table A.1 - Test report
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Road noise tests of tires in accordance with GOST R 52800-2007 (ISO 13325: 2003) |
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Test report no .: _____________________________________________________________________ |
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Tire data (brand name, model name, manufacturer): |
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__________________________________________________________________________________________ __________________________________________________________________________________________ |
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Tire manufacturer's address: _________________________________________________________________ __________________________________________________________________________________________ |
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Tire size: _____________ |
Bus serial number: _________________ |
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Nominal pressure: ____________________________ |
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Tire class: (check one box) |
Passenger cars TS(C1) |
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Freight TS(C2) |
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Freight TS(C3) |
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Appendices to this protocol: ____________________________________________________________ __________________________________________________________________________________________ |
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Declared sound level: ____________ dBA |
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at reference speed: |
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Comments (at other speeds) _________________________________________________________ |
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Responsible for testing: _____________________________________________________ |
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Applicant's name and address: _____________________________________________________________ __________________________________________________________________________________________ |
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Date of drawing up the minutes: ______________________________ Signature: |
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Table A.2 - Additional data / information regarding tire noise tests
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Table A.3 - Test results for a motor vehicle
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Test number |
Speed, km / h |
Direction of movement |
Sound level (without temperature correction) on the left side, dBA |
Sound level (without temperature correction) on the right side, dBA |
Air temperature, ° C |
Track surface temperature, ° C |
Sound level (with temperature correction) on the left side, dBA |
Sound level (with temperature correction) on the right side, dBA |
Notes (edit) |
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The declared value of the sound level _________ dBA |
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NOTE The declared sound level value should be calculated at the reference speed as a result of regression analysis after temperature correction and rounding to the nearest integer value. |
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Appendix B
(required)
Trailer method
B.1. Traction vehicle and trailer
B.1.1. General Provisions
The test complex should consist of two parts: traction TS and a trailer.
B.1.1.1. Traction vehicle
B.1.1.1.1. Sound level
Traction motion sound TS should be minimized by applying appropriate measures (installation of low-noise tires, screens, aerodynamic fairings, etc.). Ideally sound level traction vehicle must be at least 10 dBA below the total sound level traction vehicle and a trailer. In this case, there is no need to carry out multiple measurements with traction TS... It is possible to increase the measurement accuracy due to the lack of subtraction of the sound level of the traction TS... The required level difference and the calculated bus sound level are given in B.4.
should not change during the test runs of the traction TS with a trailer. To ensure a stable load during testing, the traction TS if necessary, load with ballast.B.1.1.2. Trailer
B.1.1.2.1. Single axle frame trailer
The trailer must be a single-axle frame trailer with a hitch and a device for changing the load on the tires. Tires must be tested without fenders or wheel covers.
B.1.1.2.2. Coupling length
Hitch length measured from the center of the drawbar TS to the trailer axle, must be at least 5 m.
B.1.1.2.3. Track width
The horizontal distance measured perpendicular to the direction of travel between the centers of the contact spots of the trailer tires with the road surface should not exceed 2.5 m.
B.1.1.2.4. Camber and convergence
Camber and toe angles of all tires tested shall be zero under test conditions. The error for camber should be ± 30 "and for toe angle ± 5".
B.2.
For tires of all classes, the test load shall be (75 ± 2)% of the rated load. Q r
B.2.2. Tire pressure
Each tire must be inflated to pressure (cold tires)
where P t- test pressure, kPa;
Rr- nominal pressure, which is equal to:
250 kPa for standard C1 class tires;
290 kPa for C1 class reinforced tires;
The pressure value indicated on the sidewall for tires of classes C2 and C3;
Q r - maximum mass load corresponding to the LI bus;
B.3. Measurement technique
B.3.1. General Provisions
When carrying out tests of this type, two groups of measurements must be performed.
a) First, the traction TS and record the measured sound levels in accordance with the procedure described below.
b) The tests are then carried out traction vehicle together with the trailer and record the total sound levels.
The tire sound level is calculated using the method described in B.4.
B.3.2. Vehicle location
Traction TS or traction TS together with the trailer should approach the line E - E with the engine off (muffled) at neutral speed with the clutch disengaged; middle line TS should coincide as much as possible with the center line of movement, as shown in figure B.1.
B.3.3. Travel speed
Before entering the test area ( E - E or F - F, see figure B.1) traction TS must be accelerated to a certain speed, so that the average coasting speed TS with the engine off, together with a trailer between the lines A - A and V - V the test site was (80 ± 1.0) km / h for class C1 and C2 tires and (70 ± 1.0) km / h for class C3 tires.
B.3.4. Required measurements
B.3.4.1. Noise measurements
Record the maximum sound levels measured during the passage of the test tires between the lines. A - A and B - B the course test site (see Figure B.1). Additionally, when passing the measurement zone, it is necessary to record the sound level values for each microphone at time intervals not exceeding 0.01 s, using an integration time equivalent to the time characteristic F sound level meter. This data in the form of the dependence of sound levels on time is required for subsequent processing.
1 - trajectory of movement; 2 - reference point TS; 3 - microphone position; A - A and A " - A ", B - B and B " - B ", E - E and E " - E ", F - F and F " - F ", O - O and O " - O "- reference lines
Figure B.1 - Diagram of the test site and the location of the vehicle with a trailer for recording the dependence of the sound level of tires on time
The measurement of the dependence of the sound level on time begins with the determination of the lines A" - A " and B " - B " as shown in Figure B.1. These lines are defined with leading distance d t from trailer wheel axles to the reference point of the traction TS(see Figure B.1.). The reference point is the point TS, at the intersection of which the lines A" - A " and B " - B " celebrate beginning and the end check-in time sound. When passing as TS with a trailer, and a single traction TS use the same registration method sound level.
B.3.4.2. Additional measurements
During each pass, the following information is recorded:
a) ambient temperature;
b) the surface temperature of the course;
c) whether the wind speed exceeds 5 m / s (yes / no);
d) whether the difference in sound level between the measured and background noise is 10 dBA or more (yes / no);
e) average speed of traction TS between the lines A - A and B - B.
B.3.5. Average sound levels
Record changes over time in sound levels and the maximum level reached during each pass for each microphone. Continue measurements until the five maximum sound levels recorded for each speed of movement and for each position of the microphone do not differ by more than ± 0.5 dBA from their average values without temperature correction. In accordance with 7.2, these average maximum levels and averaged time dependence levels should be temperature corrected. The temperature-weighted values obtained for both microphones are then averaged to determine the microphone-averaged sound levels and time dependence. Next, the arithmetic mean of the two sound levels averaged over the microphones is calculated for traction vehicle single and together with a trailer and record the average sound level of the passage. Use the same averaging technique for sound level versus time. In the following calculations, the following average values of the sound level versus time are used:
`L T is the average value of the maximum sound levels traction TS without a trailer;
L T (t) - average value of time dependence of sound levels traction TS without a trailer;
`L Tp is the average value of the maximum sound levels in the test passage (traction TS together with a trailer);
L Tr (t) is the average value of the time dependence of sound levels in the test passage (traction TS together with a trailer).
B.3.6. Synchronizing Time Dependency Records
When crossing traction TS the lines O" - O" a sync pulse must be recorded together with the sound level. This pulse should be used to accurately align signals over time when averaging and subtracting. levels.
B.3.7. Test procedure
The test procedure with a trailer consists of the following steps.
a) Preparation
1) Set the reference point on the towing TS for time synchronization.
2) Measure d t(see figure B.1).
3) Determine the position of the lines E " - E ", A " - A ", O" - O", B" - B " and F " - F" on the track test site as shown in Figure B.1. Set the recording timing devices so that the audio level recording starts on the line E " - E " and ended on the line F " - F ".
4) Average speed between lines A - A and B - B shall be equal to (80 ± 1.0) km / h for tires of classes C1 and C2 and (70 ± 1.0) km / h for tires of class C3. The speed is measured from A - A before B - B, which for the time readout sensor on the towing TC equivalent to a stretch from A " - A " before B" - B ".
5) Install the data recorder in such a way that the recording of time-consistent sound levels is carried out in the area from the lines E" - E " to the lines F " - F" both in single and in joint tests with a trailer. Install a synchronization sensor for time sequences of sound levels relative to the line O" - O" in accordance with B.3.6.
6) Check instruments for measuring air temperature and wind speed.
b) Single test (pulling vehicle without trailer) at least five passes
1) Record the maximum sound level and the time variation of the sound level in each pass and for each microphone position. These measurements are continued until the maximum sound level at each measurement point does not differ by more than ± 0.5 dBA from their average value.
4) Perform steps 1) to 3) from the beginning to the end of each test series. Traction test TS should be carried out every time the air temperature changes by 5 ° C or more during the test.
c) Joint test (towing vehicle with trailer) at least five passes
1) Record the maximum sound level and the time variation of the sound level in each pass and for each microphone position. These measurements are continued until the maximum sound level differs by more than ± 0.5 dBA from their average value at each measurement point.
2) Carry out temperature correction of five dependences of sound levels on time and maximum sound levels within ± 0.5 dBA of their average value.
3) For these five time dependences of sound levels, calculate the average sound level.
See Tables B.1 and B.2.
AT 4. Determination of tire sound levels
B.4.1. Consideration of the noise effect of a traction vehicle
Before you can determine the noise level of a tire when coasting, you need to make sure that it can be calculated. For a correct calculation of the tire noise level, there must be a sufficient difference between the sound levels measured for a single TS, and sound levels TS with a trailer. This difference can be checked in two ways.
a) Difference in maximum sound levels not less than 10 dBA
If for both measuring points the difference in the mean value of the sound levels TS together with the trailer and the average value of the maximum sound levels of a single traction TS is at least 10 dBA, effective measurements can be made. In this case, it is assumed that all other requirements regarding environmental conditions, background noise, etc. are fulfilled. In this special case, the tire noise level is equal to the average value of the maximum level measured for TS together with a trailer:
L tire = `L Tr,
where L tire - the sound level of the tire itself (i.e. the value to be determined), dBA.
b) Difference in maximum sound levels less than 10 dBA
If the difference in mean value of sound levels TS together with the trailer and the average value of the maximum sound levels of a single traction TS for both or one measuring point less than 10 dBA, further calculations are required. These calculations use the corrected average of the sound levels versus time.
B.4.2. Calculations based on time dependences of sound levels
To be determined sound level tires is the difference between the average sound levels TS with trailer and single traction TS... To calculate this difference, the temperature-weighted average of the sound level versus time is subtracted from the analogous value for TS with a trailer. The average sound levels over five passes, in which the maximum sound levels differ by less than ± 0.5 dBA, are calculated as described above. An example of sound levels versus time is shown in Figure B.2.
1 - traction TS; 2 - TS with trailer
Figure B.2 - Coasting sound levels versus time for the trailer test method
After bringing the time dependencies to the origin relative to the line O" - O", the main parameter for the analysis is the difference between the average dependence of the level on time for the traction TS together with a trailer and an average level dependence on the time of a single TS at the same point. This level difference L Tr - L T is shown in Figure B.2.
If this difference is not less than 10 dBA, then the levels measured for traction TS with a trailer, are valid values for the tested tire; if this difference is less than 10 dBA, then the bus sound level is calculated by logarithmically subtracting the sound level value for a single TS from meaning for TS together with a trailer as shown below. The logarithmic difference is expressed in terms of the mean values of the time dependences indicated above and shown in Figure B.2. Tire Sound Level to be Determined L tire, dBA, is calculated by the formula
where L T p is the maximum sound level, dBA for the test passage ( TS together with a trailer);
L T is the sound level of the traction TS without trailer, dBA, obtained for the same position TS as L Tr.
B.4.3. Sound level determination method
If the average value of the maximum sound levels for traction TS with a trailer for the right and left microphones exceeds the equivalent level for a single TS not less than 10 dBA, the bus sound level is equal to the sound level TS with a trailer (calculation results are shown in Table B.5) and therefore the procedures a), b) and c) below are not followed. However, if this difference is less than 10 dBA, then the following procedures are performed:
a) Align the beginning of the recording time dependence of sound levels for a single TS and TS together with the trailer and determine the arithmetic level difference for each time increment. Record this difference in sound levels at the point of maximum level for TS with a trailer. Repeat this step for each set of test passes.
If the registered difference exceeds 10 dBA, then the sound levels of the tires are equal to the sound levels TS with a trailer.
b) If the calculated difference is less than 10 dBA and more than 3 dBA, then the sound level of the tires is determined as the logarithmic difference between the maximum value of the sound level versus time for traction. TS with a trailer and the average value of the dependence of the sound level on the time of a single TS at the time corresponding to the maximum sound level for TS with a trailer.
c) If the calculated difference is less than 3 dBA, the test results are considered unsatisfactory. Sound level TS must be reduced to such a value that the specified difference becomes more than 3 dBA, which is necessary for the correct calculation of the tire sound level value.
See Tables B.1 and B.2.
B.5. Test report
The test report should include the following information:
b) meteorological conditions, including air and test site surface temperatures for each pass;
c) an indication of when and how the surface of the test site was checked for compliance with the requirements of GOST R 41.51;
d) the width of the rim of the test tire;
e) tire data, including manufacturer name, brand name, trade name, size, LI or load capacity, speed category, pressure rating and tire serial number;
f) type and group of test TS, model year and modification information (design changes) TS regarding its noise characteristics;
g) a description of the test fixtures specifying the hitch length, camber data and toe at test load;
h) tire load in kilograms and percentage LI for each test tire;
i) air pressure in kilopascals (kPa) for each test tire (cold condition);
j) the speed at which TS moves past the microphone on each pass;
k) maximum sound levels for each coasting pass for each microphone;
l) maximum sound level, dBA normalized to the reference speed and temperature corrected to one decimal place.
Tables B.1 and B.2 provide test report forms and additional data records regarding tire noise tests. Tables B.3, B.4, B.5, B.6 and B.7, respectively, give examples of recording the results of tests of traction TS, TS with a trailer, checking the suitability of the test results, checking the calculations for the time dependence, the difference in sound level and the calculation of the sound level of the tires.
Table B.1 - Test report
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Test to determine the noise level from contact of tires with the road surface during coasting in accordance with GOST R 52800-2007 (ISO 13325: 2003) |
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Test report number: ________________________________________________________________ |
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Tire data (trade mark, trade mark, manufacturer): ___________________________________ __________________________________________________________________________________________ |
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Manufacturer's data on the commercial use of tires: _____________________________________ __________________________________________________________________________________________ __________________________________________________________________________________________ |
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Manufacturer's address: ___________________________________________________________ __________________________________________________________________________________________ |
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Tire size: _______________________________ Serial No. ___________________________________ |
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Nominal pressure: ___________________ |
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Tire class: (check one box) |
Passenger car (C1) |
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Truck (C2) |
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Truck (C3) |
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Appendices to this Protocol: _________________________________________________________ __________________________________________________________________________________________ |
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Sound level dBA at reference speed: |
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