RU2231769C2 - Vehicle engine unit acoustic test stand - Google Patents

Abstract

FIELD: mechanical engineering; internal combustion engines; test facilities.

SUBSTANCE: invention relates to checking and diagnostic equipment, namely, to stand for carrying out vibroacoustic tests of internal combustion engines. Proposed stand for acoustic tests of vehicle engine unit has grid floor of test chamber, balancing induction machine installed on vibration isolated foundation base to transmit (brake) torque to internal combustion engine under testing by means of flexible endless member. Engine to be tested is installed on load-bearing frame mounted on vertical carrying posts. At least part of outer surface of walls of load-bearing frame is hermetically enclosed by detachable volumetric noise absorbers made of porous fibrous or foamed noise-absorbing material whose surface is lined with thin gas-and-moisture resistant envelope transparent to noise. Load-bearing frame, including detachable volumetric noise absorbers, is arranged under plane of noise0transparent grid floor of test chamber.

EFFECT: improved accuracy and reliability of results of vibroacoustic test of internal combustion engine in vertical engine unit.

3 cl, 3 dwg

Description

The invention relates to control and diagnostic equipment, in particular to a test bench for conducting vibroacoustic bench tests of internal combustion engines (hereinafter ICE).

To determine the main technical indicators of internal combustion engines (hereinafter - ICE), which are an integral part of the power unit of a vehicle (hereinafter - SA), special test benches equipped with various devices and measuring equipment are used. The main components of the CA include both the internal combustion engine itself and individual transmission units - the clutch, gearbox, arranged in a single power monoblock. As a test object, as a rule, ICE acts as the main source of vibro-acoustic radiation. For the convenience of mounting ICE on a stand, as a rule, a standard clutch housing SA is used as a connecting mounting area to the mounting elements of the stand.

As a basic equipment test bench CA contains:

- an autonomous (vibration-insulated) foundation for absorbing vibrations arising due to the action of unbalanced forces and moments of inertia in the internal combustion engine;

- foundation plate (groove) for installing the investigated SA and the brake;

- racks for installation and fastening of SA on the base plate;

- a load brake (hydraulic, electric) to absorb the power developed by the internal combustion engine with a torque measuring device on the motor shaft (brakes);

- a shaft and special couplings for connecting the ICE crankshaft to the brake shaft;

- devices and communications for supplying a cooled lubricating oil, engine coolant to the engine cooling system, exhausting the exhaust and crankcase gases of the engine;

- devices and communications for supplying ICE with fuel and air with appropriate sensors and devices for measuring flow, temperature, air and fuel pressures;

- special devices for regulating and determining individual parameters that affect the working process and ICE indicators (ignition timing, composition of the mixture, timing of the timing of the start of injection);

- systems that provide regulation and control of CA during testing;

- a remote control with the launch and control bodies of the CA located on it;

- Instruments for monitoring the operation of SA and instruments for recording measured values;

- additional devices and instruments intended for special studies in order to determine individual parameters of SA (toxicity, smoke, noise, vibration, thermal stress, deformation of individual parts, etc.).

Known technical solution for the execution of the stand for running and testing the internal combustion engine (RF patent No. 2107175, according to the application 96114020), containing the base, load (brake) and connecting devices. On the base are fixed longitudinal guides on which a frame is made, made in the form of autonomous beams. Beams are installed with the possibility of movement along the longitudinal rails and fixing relative to them. Transverse guides are fixed on the beams, on which racks are installed with the possibility of moving along them and fixing. The racks are fixed lodgment for placing the engine with the ability to move and fix in a selected direction.

The disadvantages of this technical solution are:

- rigid transmission of vibrational excitation from the investigated internal combustion engine to the connecting metal elements of the base and connecting devices of the stand (lodges, racks, transverse and longitudinal guides, autonomous frame beams) and, as a result, intense noise radiation from these elements into the space of the test room (motor box) ;

- hard and intense transmission of excitation from a working load (brake) device (electric machine) to the metal elements of the base and connecting devices of the stand (lodges, racks, transverse and longitudinal guides, autonomous frame beams);

- emission of airborne noise into the space of the test room of the engine box directly by the body and fan of the electrical machine of the loading device.

Due to these shortcomings, this type of stand concept did not find application in the practice of vibroacoustic testing of internal combustion engines, primarily due to the fact that it is necessary to minimize extraneous (in addition to the internal combustion engine under investigation) noise emissions from drive mechanisms and systems of bench equipment of the motor box.

For conducting vibroacoustic bench research and development work on internal combustion engines, specialized load stands installed in special acoustic (semi-muffled or anechoic) chambers [for example, 1, 2, 3] have found wide application:

[1] Adam Gavine. The American Way. Testing Technology International, November, 2000, p. 28 ... 31.

[2] GUP NITSIAMT “The acoustic center will perform:”. Automotive Industry, 2000, No. 11, 1.

[3] Peter Gutzmer und Reimer Pilgrim. Motorakustische Versuchs-und Меβtechnik bei Porsche. MTZ, Motortechnische Zeitschrift, 48 (1987), 2, 47 ... 50.

In particular, in [1] an example of using a semi-muffled acoustic camera of the Chrysler company (USA) is given, in [2] - an acoustic motor stand of the central avtopolygon GUP NITSIAMT (Dmitrov, Moscow Region) with a hard sound-reflecting floor, on a groove plate which with the help of special racks the studied ICE is fixed. The brake (or drive - in the engine scrolling modes without implementing the workflow in it) bench installations (there are 2 of them) are located at the same level outside the acoustic chamber and are located outside the chamber walls in the adjacent room (machine room). The ICE under study with a brake balancing machine is connected using special drive shafts (power take-off shafts), which transmit torque or braking torque between them. The end sections of the drive shafts are fixed with special racks to the groove plate and directly to the surface of the chamber floor. Pipelines and various communication elements of the power supply, cooling, and exhaust gases are removed from the space of the acoustic chamber through special soundproof openings in the floor (groove plate) of the chamber to the machine room of the stand, equipped with various technological systems and units for ensuring the functioning of the stand. The disadvantages of the used concept of an acoustic motor stand is the use of a camera with a hard sound-reflecting floor that distorts the real sound field of the ICE under study (in particular, sound emission from the lower part of the ICE located in the immediate vicinity of the sound-reflecting floor surface, which, as a rule, is common for all piston ICEs most noise-vibrating). It is in this connection that the lower engine zone is of the greatest practical interest for ICE researchers and closers and requires the most time-consuming and, if possible, the most accurate and objective studies to be carried out in this zone. On the other hand, the use of long cardan shafts with thrust bearings installed in vertical racks mounted on a groove plate and directly on the chamber floor as connecting drive elements connecting the ICE crankshaft and the brake machine power take-off shaft causes problems of their alignment with the crankshaft of the test ICE and, as a consequence, the generation of vibrational forces at the frequencies and ordinal harmonics of their rotation, transmitted via reference links as directly to the ICE under study, causing it to be additional noise emission, as well as to some attached structures of the acoustic chamber (for example, half-chambers), which entails additional distortion of the recorded noise characteristics of both the ICE under study, and the emission of “spurious” sound directly by the protective casings of the test shafts, as well as the emission of “spurious” sound directly from the floor acoustic chamber, due to the transmission of this vibrational excitation to the floor (groove plate) through the supporting racks of the shafts.

A more progressive method for studying and recording the acoustic energy emitted by ICE under bench conditions is to use the concept of an acoustic motor stand described in publication [3] - PROTOTYPE, used in the Porsche Research Center (Germany). In this case, it provides for the use of a brake (load) stand installed in the center of the chamber below the floor surface of a completely muffled anechoic acoustic chamber. The transmission of torque (braking) is carried out with an endless flexible connection - smooth transmission. In this case, the floor of the acoustic chamber is made completely vibration-proof from an autonomous foundation on which a drive (brake) stand is installed, and its surface (floors) is covered with effective sound-absorbing material (special sound-absorbing wedges). The engine body, as an object of study, in this case is located near the geometric center of the airspace of the chamber, i.e. in the zone farthest from sound-reflecting surfaces (with “best acoustics”). The lower zone of the ICE under study is not located near the sound-reflecting surface of the floor, as was the case in [1] and [2], but is open to qualitative, objective measurements of the acoustic field parameters of the ICE under study. Thus, this design [3] of the bench for acoustic research of internal combustion engines is more advanced and is accepted as a prototype.

At the same time, in the well-known bench for acoustic research of internal combustion engines [3], a supporting power frame is used, made in the form of 4 vertical posts, on which a square section supporting frame is mounted rigidly on top, located in the same plane with a translucent floor. Such a spatial diagram of the power frame of the acoustic motor stand determines the location of the vibration-excitable and vibration-transmitting metal structure of the supporting frame near the measuring surface, with installed measuring microphones around the ICE under study, which directly affects the accuracy and reliability of the results of acoustic research of the test object. The vibration generated by the drive (brake) elements of the stand is transmitted directly to the load-bearing power frame (frame, vertical load-bearing posts) mainly via support links and connecting elements, primarily through the housing of the upper support bearing assembly, which is rigidly fixed to the frame (the requirement of rigid fixation of the upper support bearing and drive housing is necessary to ensure high-precision alignment of the upper and lower shafts of the belt drive and to ensure the constancy of the value Leah belt tension throughout the speed range of the drive stand) and by a supporting frame (support) of the casing of the connecting shaft between the internal combustion engine and an upper shaft support bearing reradiated in the form of interference pattern noise which distorts the test results of noise measurement DIC. The design disadvantage of the supporting spatial power frame of the acoustic motor stand is also the large sound reflection area of the external surfaces of the structural components, which leads to the appearance of additional sound reflecting effects that distort the real (free) sound field around the object under study (ICE).

The proposed solution allows to eliminate the above disadvantages.

The essence of the invention lies in the fact that in a known test bench for acoustic research of a vehicle CA, including, in particular, the grating floor of the test chamber mounted on a vibration-insulated foundation, a balancing asynchronous machine that transmits by means of flexible endless communication the torque (braking) moment of the ICE mounted to load-bearing frame mounted on vertical load-bearing posts, at least part of the outer surface of the walls of the frame of the power frame is hermetically enclosed removable volumetric sound absorber made of fibrous or porous sound-absorbing foamed material whose surface is lined with a thin sound transmission, gazovlagonepronitsaemoy shell, wherein the supporting frame of the power frame, including removable volumetric sound absorbers, sound transmission is placed under the plane of the grid floor of the test chamber. The structure of volumetric sound absorbers can be made on the basis of basalt or glass fibers, or open-cell polyurethane foam. The sheath of volumetric absorbers can be made of fiberglass, aluminized lavsan film or urethane film.

The invention is illustrated in the drawings.

In FIG. 1 presents the claimed as an invention stand for acoustic research CA vehicle installed in an anechoic acoustic chamber.

In FIG. 2 shows a top view of a structural fragment of the proposed test bench for acoustic research of SA, containing a translucent grating floor of the test chamber mounted on the supporting frame of the studied ICE, a protective casing of the intermediate driveshaft and the housing of the upper support bearing assembly.

In FIG. Figure 3 shows a fragment of the design of the frame of the load-bearing power frame of the proposed stand for acoustic research of acoustic systems with volumetric sound absorbers installed on it.

The invention depicted in FIG. 1, is a stand for acoustic studies of a vehicle CA mounted in an anechoic acoustic chamber 1, with a drive (brake) balancing asynchronous (or direct current) machine 3 mounted on a stand-alone vibration foundation insulated by special springs 4 and installed below the floor surface 2. Internal concrete the shell 6 of the chamber 1 is installed around the perimeter of the floor 7 on special springs 8 and is completely vibration-proofed from the structure of the outer concrete shell 9 (the principle of construction is “chamber in chamber”). The floor 10 of the acoustic chamber 1 is vibration-insulated from the foundation 5, on which a balancing asynchronous machine 3 is installed, with rubber seals 11. The surface of the floor 10, 2, walls 6 and ceiling 12 of the chamber 1 is covered with special sound-absorbing wedges (wings) 13. The balancing asynchronous machine 3 transmits torque (brake) moment through the lower shaft 14, installed in the housing 15 of the lower support bearing assembly, the drive belt 16, the upper shaft 17, closed by a protective casing 18, the intermediate driveshaft 19.

The rotation zone of the drive belt 16 is closed by a protective casing 20. The test object - CA 21 is mounted on vertical racks 22 of the ICE mounting device on the bench through autonomous, rubber-metal elastic supports 23 spaced apart on both sides of the ICE cylinder block and rubber support 24 -metal elastic cushions 25 to which the clutch housing 26 of the test CA 21 and the housing of the transitional bearing assembly 27 are attached. Longitudinal guides 28 of the ICE mounting device and the housing of the upper bearing of the assembly 29 are rigidly mounted on the supporting frame 30 of the power frame mounted on the supporting vertical struts 31. The transverse guides 32 freely move along the longitudinal guides 28 with the ability to be fixed in the required position. The floor of the test chamber 1 is a soundproof grating 33, vibration-insulated from the supporting frame 30 power frame. The air cavity of the chamber 1 is ventilated by a high-capacity supply 34 and exhaust ventilation 35. The implementation of such a spatial arrangement of the load-bearing frame of the power frame of the test bench for SAs below the plane of the translucent grating floor of the test chamber will maximize the removal of vibration-loaded, emitting “spurious” structural noise, the surfaces of the load-bearing frame from the noise measurement zone of the ICE under study, and, thus, increase the accuracy and objectivity of conducting acoustic research of the test object. The use of shortened load-bearing vertical racks gives greater rigidity to the design of the load-bearing power frame and, accordingly, less vibration load of the metal structure of the racks and the parasitic structural noise emitted by them.

In FIG. 3 shows a fragment of the design of the frame of the load-bearing power frame of the acoustic research stand of the SA claimed as an invention, comprising a load-bearing frame 30 made in the form of a closed metal box of rectangular cross section. The entire external surface of the walls of the supporting frame is covered by removable volumetric sound absorbers 36, made of porous sound-absorbing material. The outer surface of the porous structure of the sound-absorbing material of the volume absorber 36 is enclosed in a protective sound-transparent shell 37, for example, of thin fiberglass, aluminized lavsan film, urethane film, and the like. The porous structure of the absorber 36 itself can be a known porous fibrous material or foamy open-cell sound-absorbing material in the form of sheets based on basalt or glass fibers, open-cell polyurethane foam or other typical sound-absorbing material. The implementation of volumetric removable absorbers makes it possible to easily remove the absorbers (for example, during their periodic cleaning or during the installation of ICE on the stand, carrying out repair or adjustment work with a stand or investigational ICE). The protective sound-transparent shell 37 of the volume absorber 36 is made primarily of a washable, fire-resistant, moisture-oil-gas-resistant material that does not allow these substances to enter the structure of the porous absorber, which is easily subjected to vacuum cleaning or wet cleaning. The end surfaces of the absorbers in the mating zone have a lock 38 (for example, in the form of an adhesive layer), which will allow hermetic coverage of the entire external surface of the carrier frame by the structure of the absorber. The use of volumetric sound absorbers, hermetically mounted on the surface of the carrier frame, will further isolate the structural noise emitted by the metal structure of the walls of the carrier frame, and, in addition, significantly reduce the effects of sound reflection of sound waves incident on the surface of the frame from the side of the internal combustion engine and elements of the mechanical drive of the stand .

In addition, the presence of a frame of a power frame with a futurized sound-absorbing material under the grating provides free access for the operator (tester) to the ICE units and systems during their installation on stands, adjustments, diagnostic operations and other operational and measuring procedures without possible mechanical damage to the soft porous sound-absorbing structure surround sound absorbers.

Practical implementation of the proposed design of the stand for acoustic research of vehicle SA allows you to increase the accuracy and objectivity of the results of bench vibroacoustic tests of ICE in the composition of the SA.

Claims (3)

1. A stand for acoustic studies of a power unit of a vehicle, comprising, in particular, a grating floor of a test chamber mounted on a vibration-insulated foundation a balancing asynchronous machine that transmits a torque (braking) moment to a test engine mounted on a load-bearing power frame mounted on a load-bearing frame mounted on a vibration-proof foundation; vertical support racks, characterized in that at least part of the outer surface of the walls of the frame of the power frame is hermetically enclosed by removable volumetric E sound absorber made of fibrous or porous sound-absorbing foamed material whose surface is lined with a thin sound transmission, gazovlagonepronitsaemoy shell, wherein the supporting frame of the power frame, including removable volumetric sound absorbers, sound transmission is placed under the plane of the grid floor of the test chamber. 2. The stand according to claim 1, characterized in that the structure of volumetric sound absorbers is made on the basis of basalt or glass fibers or open-cell polyurethane foam. 3. The stand according to claim 1 or 2, characterized in that the sheath of the volumetric absorbers is made of fiberglass, aluminized lavsan film or urethane film.

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