RU31651U1 - DYNAMIC STAND WITH RUNNING DRUMS FOR ACOUSTIC RESEARCHES OF VEHICLES - Google Patents

Description

DYNAMIC STAND WITH RUNNING DRUMS GIVEN ACOUSTIC RESEARCHES OF VEHICLES.

The utility model relates to control and diagnostic equipment, in particular, to a test bench for studying the noise and vibration generated by a moving vehicle, for example, a car.

The solution to the problem of reducing acoustic pollution of the environment and improving acoustic comfort in the cabin (cabin) of ground wheeled vehicles is an important urgent task for developers and researchers of transport equipment, requiring large material, time and intellectual costs. The most mobile and productive processes of research and refinement of vehicles by noise and vibration comfort are experimental studies conducted in bench conditions, using a variety of techniques to simulate speed and load conditions that are identical to road (field) test conditions (for example, using dynamic stands with running drums) stationary measuring and analyzing equipment. Constant weather and road conditions independent of the test conditions, ease of removal and analysis of measuring information contribute to an ever wider

the main vibro-noise source of the vehicle is its power plant - an engine with transmission units (hereinafter referred to as the power unit), it is very important to conduct research and fine-tuning the power unit on the stand when simulating various speed and load modes (changing the engine speed, the throttle opening angle

dampers, etc.).

A fairly complete imitation of the vehicle’s driving conditions in real road conditions can be achieved on stands with running drums, the practice of which has been widely used at enterprises manufacturing transport equipment and research institutes.

For the first time in our country, a stand design with two pairs of running drums was proposed in 1924 by prof. IN AND. Forty-Novitsky, see N.Ya. Govorushchenko Diagnostics of a technical condition of cars, M., Transport, 1970, p. 141/1 /. Overseas stands with running drums appeared in the thirties. For example, in the USA, the first stands with a set of equipment began to be produced in 1935 by Bendix Corporation, P.141, / 1 /.

Structurally, these stands consist of two pairs of drums for the rear and front wheels of the car. Drums through the gearbox are connected to brake devices, see Fig. 1, p. 141, / 1 /

From U.S. Patent No. 5,465,612, IPC G01M 17/00, issued to CLAITON IND, a dynamic drum stand is known that is equipped with drive and brake mechanisms and control systems that allow them to accurately simulate real speeds, loads, inertia forces and stray loss signals characterizing Features of the movement of the car in road conditions.

Modern technologies for the study of acoustic processes that are implemented on vehicles (cars, tractors, motorcycles, etc. types of wheeled vehicles) include the use of special low-noise running drums, which allow simulating various speed and load modes of energy and transmission units of vehicles in conditions

placing them in special anechoic or semi-anechoic acoustic chambers providing free sound field conditions in the measurement zones.

One such technology is described in detail in a Walter publication.

Seeger Geraususchabstrahlung eines Verbrennungsmotors. Einfluss der Ansaug und Absauggerausche auf das Fahrzeug-lnnengerausch. Automobil-lndustrie, 1985, No. 5, p. 515 ... 526. Here, in particular, the noise levels and spectra of the intake and exhaust systems of an internal combustion engine (hereinafter referred to as ICE) were estimated at a test bench with running drums in a semi-anechoic acoustic chamber on an Opel-Kadett GSI car.

One of the important advertising parameters of stands with running drums is the total noise level of the stand at 100 km / h at 1 m above the surface of the running drums (above the floor surface of the chamber in which the stand is installed). So, in the published report SAE 971900 Design, Construction and Application of a World Class Venicle Acoustic Test Facility, F.K. Brandl, p. 241-247 (CM. Fig. 11 and Table 2) it is indicated that the noise level of the ZOLLNER stand at 100 km / h in 1 m above the drums is not more than 47 dBA, which allows AVL to carry out a variety of objective acoustic studies of cars.

A similar low-noise design of a dynamic stand with running drums is used by BMW, see publ. Rudolf Biker, Norbert Herzum, Wolfgang Keiner, Labert Ulrich. Die neuen BMW Versuchseinrichtungen fur Akustik, ATZ, 88, 1986, 219 ... 230, (CM. Fig. 3,4,5).

There is also a stand with running drums for special acoustic measurements, the Federal Republic of Germany patent No. 3715016, IPC G01M 17/00, issued to the company Daimler-Benz, for complex acoustic research of cars, including both imitation of high-speed and load modes of the power unit, and imitation the corresponding air flows around the body for research and refinement of the structures of individual body elements from the point of view of weakening the generation of aerodynamic noise at high speeds.

for vibro-acoustic studies of the car, where, along with the message to him of the specified speed and load modes, he is exposed to additional vibrational effects, reported from the drums.

A known design of a dynamometer stand with running drums installed in a muffled chamber, with fastening on the surfaces of the drums of special devices having a different shape and coating, for studying the effects on the car of roughnesses of the roadway, see publ. NIINAVTOPROM, S.A. Vorontsov, V.E. Tolsky Modern methods and means of vibration-acoustic testing of automobiles, pp. 15-20.

As a PROTOTYPE, a design of a dynamic stand with running drums for acoustic research of vehicles is adopted, which is described in the certificate of the Russian Federation for utility model No. 20791, IPC7 G01M 17/00, publ. November 27, 2001, BI No. 33.

Known designs of dynamic stands with running drums for acoustic research of vehicles for exhaust gas exhaust engines use, in particular, a technological exhaust exhaust system, including, among other things, a flexible exhaust hose of an exhaust ventilation unit located in the space of the test chamber. When conducting, first of all, studies of the sound-damping characteristics of exhaust silencers of the vehicle under investigation, a flexible exhaust hose is either not used - in this case, the engine exhausts freely (and the sound emits with an open cut of the tail pipe) into the space-acoustic chamber (see Walter Seeger Geraususchabstrahlung eines Verbrennungsmotors. Einfluss der Ansaug und Absauggerausche auf das Fahrzeug-lnnengerausch. Automobil-lndustrie, 1985, No. 5, p. 515). Or, a flexible outlet hose is mounted to an open conical socket mounted near an open cut of the tail of the exhaust pipe of the vehicle under investigation (see Utility Model Certificate of the Russian Federation No. 20399, MPK7 G10K 11/00, published on October 27, 2001, BI No. 30). The emission of exhaust gases into the room of the acoustic chamber leads to gas pollution problems

rooms, partial loss of porosity and sound-absorbing properties of sound-absorbing wall and ceiling linings of a semi-anechoic acoustic chamber due to the sedimentation of solid particles (soot) contained in the exhaust gases of the engines of the tested vehicles

means (in particular, equipped with a diesel engine). With another

On the other hand, quite often in the practice of research and development work on the vehicle’s vibration acoustics, it is necessary to exclude noise emission from the exhaust system, in particular, when separating and studying the noise of individual components and assemblies in the vehicle and compiling the equation of acoustic balance of vehicle noise sources. In this case, in known dynamic stands with running drums, exhaust exhaust gas is used with a sealed installation of a flexible exhaust hose of an exhaust ventilation unit to cut a tail pipe of the main silencer of a vehicle exhaust system. An obvious drawback of the known designs of dynamic stands with such exhaust gas exhaust is the insufficient degree of damping of the exhaust-intensive exhaust emission emitted by the exhaust system into the internal cavity of the exhaust hose. The noise propagated through such a discharge hose pipe from the exhaust side is re-emitted by the walls of the hose into the space of the semi-anechoic test chamber due to the limited sound-insulating ability of thin-walled flexible hoses, thereby adding an additional masking noise background to the measurement zone, which complicates the performance of high-quality acoustic research work that does not take into account the effect noise emission vehicle. In addition, the dynamic pulsations of the gas stream of the exhaust gases excite vibrations of the thin-walled structure of the flexible exhaust hose, subsequently reradiating in the form of additional structural spurious noise into the space of the test chamber. To eliminate these shortcomings, the application of the claimed utility model is directed. It is proposed to use mobile (mobile) as a part of a dynamic stand with running drums for acoustic research of vehicles

silencer of the technological exhaust system of the engine exhaust of the investigated vehicle.

It is well known that for damping aerodynamic noise of various power plants, vehicles and in other areas

silencers in the form of human life are widely used

expansion chambers and resonator chambers. One of such designs is described in USSR author's certificate No. 1092290 Exhaust silencer for an internal combustion engine. An advantage of such a muffler is a high degree of noise suppression of the gas-dynamic noise of the engine exhaust system with the simplicity of design, compactness and low hydraulic resistance of the exhaust tract due to the coaxial optimal arrangement of the dynamic sections of the pipes in the cavity of the muffler, which eliminates the excitation of odd eigenmodes of oscillation of the gas volume of the chamber and simultaneously eliminates the transmission excited in the chamber volume even air eigenmodes, which in the complex excludes oyavlenie dips in the frequency characteristic of noise silencing muffler expansion chamber.

A disadvantage of the known devices of this type used for damping noise is the possible undesirable distortion of the sound fields of the premises, when these silencers are located in them as cluttering the camera’s space objects, due to the inevitable effects of sound reflection of the incident (propagated) waves emitted in these rooms, for example, acoustic anechoic or semi-anechoic chambers in which the studied sound sources are located, such as internal combustion engines, compressor units, conveyor tny means and others. The inventive utility model eliminates this acoustic defect while maintaining the positive technical characteristics of the known gas silencing devices.

The essence of the utility model lies in the fact that in the well-known dynamic stand with running drums for acoustic research of vehicles, containing, in particular, a technological system for remote exhaust gas removal, including a ventilation unit for forced exhaust extraction, a ventilation duct with

gas outlet to the surrounding atmosphere, pipelines of the technological exhaust system, technological silencers, flexible exhaust hose, while an easily removable movable pipe is installed on the exhaust exhaust section located in the space of the test chamber near the tail of the exhaust pipe of the vehicle under study

(mobile) silencer of cylindrical shape, with inlet and outlet nozzles integrated into the cavity of the silencer chamber, with coaxial arrangement of nozzles, cuts of which are located at a given distance from the end walls of the chamber, equal to half the length of the air cavity of the cylinder minus 0.3 diameter of the outlet nozzle and at a distance a quarter of the length of the air cavity of the cylinder minus 0.3 of the diameter of the inlet pipe. The silencer body is preferably in the form of a multilayer sandwich structure (steel foliage-damping laminate-aluminum foil, or steel foliage-damping adhesive-steel sheet, or steel sheet-loose vibro-damping substance-steel sheet), the outer surface of which is lined with self-adhesive, sound-absorbing porous fibrous material or open with an external protective soundproof layer, while the silencer housing is mounted on the floor of the test chamber through elastic vibrations insulating elements (for example, a mat made of porous rubber or support stands such as rubber or polyurethane vibration isolators, or wheels with massive rubberized rims). The muffler body due to the connecting part of the short inlet pipe is located as close as possible to the open cut of the tail pipe of the exhaust system of the vehicle engine so that an additional muffled exhaust gas stream with weakened gas pulsations is transported through a long section of the exhaust pipe of the muffler flow, which, in combination, provides a weak re-emission of exhaust noise by the walls of the flexible hose into the acoustic measurement space which camera.

In FIG. 1 shows a semi-anechoic acoustic chamber with a dynamic stand with running drums for acoustic studies of vehicles declared as a transport model.

With reference to FIG. 1 marked:

1- semi-anechoic acoustic chamber;

2- sound-absorbing backstage;

3 - vibration damping springs;

4 - vibration base of the stand;

5-running drums;

6- electric winch;

7-vehicle;

8 - fixing cable;

9 - fixing racks;

10 - supply and exhaust ventilation;

11- video monitoring system;

12- floor test chamber;

13- flexible exhaust exhaust hose;

14- pipeline of the exhaust system;

15-technology silencer;

16- ventilation duct;

17- centrifugal ventilation unit;

18 - exhaust pipe;

19- exhaust silencer.

In FIG. 2 presents a fragment of the design of the inventive dynamic stand with running-drums for acoustic research of vehicles, containing, in particular, a silencer of the exhaust system of the exhaust gases of the investigated vehicle of cylindrical shape. The silencer housing 20 is, for example, made of sheet steel 21 or a cast structure of metal (cast iron, aluminum), a polymeric material (for example, glass-filled polyamide). In the case of using a thin-walled steel sheet, the housing 20 is preferably made in the form of a multilayer sandwich structure:

fln

22 - vibration damping laminate;

23- aluminum foil;

24 - self-adhesive sound-absorbing material (porous fibrous or open-cell foam);

25- external protective soundproof layer (for example, soundproof, non-combustible, moisture-proof, fiberglass cloth or thin, protective, heat-resistant, moisture-proof soundproof foil).

In FIG. Figure 3 shows an embodiment of the body of a cylindrical noise muffler in the form of a sandwich structure: steel sheet 21, vibration damping adhesive 26, steel sheet 27.

In FIG. 4 shows an embodiment of the body of a cylindrical noise muffler in the form of a sandwich structure: steel sheet 21, vibration damping granular material (for example, dry quartz sand) 28, steel sheet 27.

The external lining of the surface of the cylindrical silencer with sound-absorbing material makes it possible to weaken the process of reflection of sound waves due to the absorption effect of sound waves propagated in the acoustic semi-anechoic chamber, and the construction of the body in the form of a sandwich structure provides weak excitation of structural (body) noise from vibration and gas-dynamic excitation of the walls corps.

In FIG. 5 shows an embodiment of a silencer design in which the outer lining of the housing by sound-absorbing material 24 is in the form of a wedge-shaped structure. Lining of this type will allow more efficient absorption of sound waves propagating in the space of the test chamber, due to better coordination of wave impedances of sound propagation media in the zone of a porous sound absorber, increasing the surface area of the porous material.

 The inlet pipe 29 and the outlet pipe 30 are mounted in the internal cavity of the cylindrical noise silencer. The geometric arrangement of the dynamic sections of the pipes in the cavity of the silencer chamber is shown in FIG. 6. Here it is clearly seen that

real (static) sections of the nozzles are arranged coaxially to minimize the hydraulic resistance of the exhaust duct and with a shift in the direction of the end walls of the silencer by .3d to exclude the generation of odd lower eigenmodes and exclude the transmission of even lower eigenmodes of the air cavity of the cylindrical chamber of the muffler.

In FIG. 7 shows a layout of a silencer in a semi-anechoic test chamber. The noise muffler 19 is easily removable, mobile (mobile) and is installed at the minimum possible distance from the tail of the exhaust pipe 18 of the muffler of the vehicle 7 under investigation due to the hermetic connection of the connecting part of the inlet pipe 29 of the muffler

19 with the tail of the exhaust pipe 18 with a portion of the flexible hose 31 of the minimum length. The connecting part of the opposite outlet pipe 30 is connected by a long section of the flexible outlet hose 13 to the connecting elbow 32 of the exhaust system. Thus, through a long section of the exhaust hose 13, the exhaust gas stream additionally muffled by the muffler 19 is transported with weakened gas flow pulsations, which, in combination, provides weak re-emission of exhaust noise by the walls of the flexible exhaust hose into the space of the semi-anechoic chamber.

In FIG. 8-10 show various patterns of support connections of the housing

20 silencers with a floor 12 test chamber. The silencer body is mounted on the floor of the test chamber through an elastic mat of

porous rubber 33 (see Fig. 8), either on vibration isolating support stands 34, such as rubber or polyurethane vibration isolators (see Fig. 9), or on rubberized wheels 35 (see Fig. 10). Such support bond schemes make it possible to attenuate the transmission of vibration by the hard way to the floor of the test chamber.

The design of the mobile (mobile) type silencer makes it easy to mount the silencer and the exhaust system in general, regardless of the specific location of the tail silencer pipe (to the left or right of the longitudinal axis of the investigated transport

facilities). In FIG. 11 is a diagram illustrating the installation of a silencer depending on the location of the tail pipe of the silencer of a vehicle.

Thus, the application in the inventive dynamic stand with

running drums for vehicle acoustic research

the exhaust silencer of the exhaust gas system will additionally drown out the noise emitted by the exhaust gas exhaust system, weaken the gas-dynamic pulsations of the exhaust gases in the path of the flexible exhaust hose of the technological exhaust gas system, and reduce the distortion of sound fields in the space of the acoustic chamber caused by sound reflection from the silencer body beyond due to the absorption of sound waves by the sound-reflecting lining of the silencer body, to weaken the vibrational excitation of the floor acoustically camera from the body of the muffler through the supporting connection, and carry, so high-quality acoustic research on the vibro-acoustic fine-tuning vehicles.

ice / WS3

Claims (1)

A dynamic stand with running drums for acoustic research of vehicles mounted in an acoustic semi-anechoic chamber, containing, in particular, a technological system for remote exhaust gases of the engine of the vehicle under study, including a ventilation unit for forced exhaust extraction, a ventilation duct with the outlet of gases to the surrounding atmosphere, pipelines of the technological exhaust system, technological silencers, flexible exhaust hose, characterized by m, that in the exhaust gas discharge section located in the space of the test chamber, near the tail of the exhaust pipe of the test vehicle, an easily removable movable (mobile) silencer of cylindrical shape with coaxially arranged inlet and outlet pipes integrated into the cavity of the silencer chamber is installed, the sections of which are placed on a given distance from the end walls of the chamber equal to half the length of the air cavity of the silencer chamber minus 0.3 of the diameter of the outlet pipe and at The fourth part of the length of the air cavity of the silencer chamber minus 0.3 of the diameter of the inlet pipe, the silencer body is made in the form of a multilayer sandwich construction, the outer surface of which is lined with self-adhesive sound-absorbing porous fibrous or open-cell foam material with an external protective soundproof layer, while the silencer body mounted on the floor of the test chamber through elastic vibration-isolating elements (for example, a mat made of porous rubber or support stands such as rubber or iuretanovyh isolators, or wheels with solid rubber coated rims), the body of the muffler due to the connecting portion shorter transfer tube is located in the vicinity of the open-cut tail pipe of the exhaust system of the vehicle engine exhaust.