RU23501U1 - SILENT STAND FOR TESTS OF INTERNAL COMBUSTION ENGINES - Google Patents

Description

high speed low noise test bench for internal combustion engines. The utility model relates to control and diagnostic equipment, to a test bench for conducting vibration-acoustic bench tests of internal combustion engines (hereinafter ICE). To determine the main technical parameters of the internal combustion engine, special test benches are used, equipped with various devices and measuring equipment. As a basic equipment, the ICE test bench contains: an autonomous (vibration-insulated) foundation for absorbing vibrations arising from the action of unbalanced forces and moments of inertia in the ICE; foundation plate (groove) for installing the ICE and brake under study; racks for installing and fixing ICE on a foundation plate; load brake (hydraulic, electric) to absorb the power developed by the internal combustion engine with a torque measuring device on the motor shaft (brakes); shaft and special couplings for connecting the ICE crankshaft to the brake shaft; devices and communications for supplying to the internal combustion engine a cooled lubricating oil, a cooling liquid of the internal combustion engine cooling system, exhaust into the atmosphere exhaust and crankcase gases of the internal combustion 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 workflow and engine parameters (ignition timing, mixture composition, timing of the start of injection);

a remote control with the ICE start-up and control bodies located on it;

instruments for monitoring the operation of the engine and instruments for recording measured values;

additional devices and devices intended for special studies in order to determine the individual parameters of the internal combustion engine (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 guides 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 internal combustion 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 beam of the frame) 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 the 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 motor box directly by the body and fan of the electrical machine of the load device;

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first of all, due to the fact that it is required to minimize extraneous (in addition to the ICE being studied) noise emissions from drive mechanisms and stand equipment systems of a 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, are widely used.

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

2 GUP NITSIAMT “Acoustic center will perform :. Automotive industry, 2000, No. 11.1.

3 Peter Gutzmer und Reimer Pilgrim. Motorakustische Versuchs-und Mer technikbel Porsche. MTZ, Motortechnische Zeitschrift, 48 (1987), 2, 47 ... 50.

In particular, in 1 there is an example of using a semi-muffled acoustic camera from Chrysler (USA), in 2 - an acoustic motor stand of the GUP NITSIAMT central autopolygon (Dmitrov, Moscow region) with a hard sound-reflecting floor, on the groove plate of which using special stands the studied ICE is fixed. The brake (or drive - in the modes of scrolling ICE without implementing the workflow in it) the stand settings (there are two of them) are 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 provide transmission of 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, exhaust gas systems 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 the most noise-vibrational for all piston ICEs). It is in this regard that the lower ICE 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 research to be carried out in this zone. On the other hand, the use of long driveshafts with thrust bearings installed in vertical racks mounted on a slot plate and directly on the chamber floor as connecting drive elements connecting the ICE crankshaft and power take-off of the brake machine of the stand 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 investigation, causing it to complement full noise emission, as well as to some attached structures of the acoustic chamber (for example, the floor of the chamber), 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 covers of the shafts of the stand, as well as the emission of“ spurious sound directly by the acoustic floor the camera, 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, used in the research center of Porsche (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 the 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 ICE case, 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 the sound-reflecting surfaces (with "the best acoustics). The lower zone of the ICE under study is not located near the sound-reflecting surface of the floor, as

THIS took place in 1 and 2, and is open to qualitative, objective measurements of the acoustic field parameters of the ICE under study. Thus, this design 3 of the acoustic motor stand is more advanced and is adopted as a prototype.

At the same time, one of the intense noise emitters of such an improved stand is the housing of the upper support bearing assembly, which is a massive metal base, which is closed on top by a removable thin-walled metal cover. A significant drawback of the known design of the housing of the upper support bearing assembly is the high vibroacoustic excitability of the cap at the resonant frequencies of oscillation of its walls, as well as the weak sound-insulating ability of the thin-walled metal structure of the cap walls from the transmission of airborne noise from the casing cavity, which leads to additional noise emission into the ICE noise measurement zone during the acoustic tests of the ICE under study, and, thus, to reduce the accuracy of noise measurements, we radiate of the test object, and the reliability of acoustic research work. Noise from the noisy area of the engine room (for example, noise from an asynchronous balancing machine, fans, pumps) through the connecting channel of the drive belt casing freely penetrates the interior of the housing of the upper support bearing assembly, excites the metal walls of the housing cover by air, and, ultimately, is re-emitted into the test chamber room in the form of a spurious noise signal, thereby distorting the real sound field around the ICE under study. Rotating drive elements of the stand (shaft, thrust bearings, belt) are additional sources of vibration and noise in the space of the housing of the support bearing assembly, generating corresponding sound waves also transmitted to the space of the anechoic chamber with high vibrational excitability and weak sound-insulating ability of the walls of the housing cover of the upper support bearing node. In addition, the metal walls of the lid are excited in a rigid way transmitted from the extremely vibroactive metal base in contact with them. In this case, the vibrating walls of the lid emit spurious structural noise into the ICE research area with installed measuring microphones, adversely affecting the state of the free sound field around the test object. The proposed technical solution allows to eliminate the

above disadvantages.

The essence of the utility model lies in the fact that in the known low-noise test bench for ICE mounted in a damped anechoic acoustic chamber containing, in particular, a support frame mounted vibro-insulated from the floor of the acoustic chamber, on which the massive metal base of the housing of the upper support bearing assembly is rigidly fixed kinematically connected with the drive shaft of the balancing machine and the drive shaft of the investigated internal combustion engine mounted on the longitudinal beams, fixed mounted on a supporting frame, while the housing of the upper support bearing assembly is covered by a protective casing, the walls of the housing of the casing are damped from the inside and outside with a layer of vibration-damping material, from the outside the housing of the casing with the formation of a closed cavity is covered by a supporting frame made of pipes with a closed rectangular profile and fixed on the basis of the housing of the upper support bearing assembly, the internal cavity of the pipes is filled with a loose vibration-damping soundproofing substance AND / OR com thin-walled perforated metal panels are fixed on the walls of the supporting frame with a positional mixture of several bulk vibration-damping materials, while a closed cavity formed between the walls of thin-walled perforated metal panels of the supporting frame and the casing is filled with porous sound-absorbing material. The walls of the casing, for example, can be lined with a layer of self-adhesive AND / OR thermo-melting bitumen laminate. The internal cavity of the carcass tubes, for example, may be filled with quartz sand. A closed cavity formed between the walls of thin-walled perforated metal panels of the supporting frame and the casing body is filled with super-thin basalt fiber, or fiberglass, or open-cell polyurethane foam, or an effective sound-absorbing material similar in physical and mechanical properties.

In FIG. 1 shows a low-noise research bench for testing internal combustion engines in a muffled anechoic acoustic chamber 1, with a drive (brake) balancing asynchronous (or direct current) machine 3 mounted below the floor surface 2 on a stand-alone foundation vibration-proofed by special springs 4 5. Internal concrete shell 6 of chamber 1

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installed around the perimeter of the floor 7 on special springs 8, and is completely isolated from the outer concrete shell 9 (the principle of construction is “chamber in chamber”). The floor 10 of the acoustic chamber 1 is echo-insulated with rubber seals 11 in the interface zones with the adjacent surfaces of the foundation 5, on which a balancing asynchronous machine 3 is installed. The surfaces of the floor 10, 2, walls 6 and ceiling 12 of the chamber 1 are covered with special sound-absorbing wedges (wings) 13. Balanced asynchronous the machine 3 is fixed to the foundation floor 5 and transmits torque (braking) 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 skin ear 18. The rotation area of the drive belt 16 is closed by a protective casing 19. Test object - ICE 20 is mounted on vertical racks 21 of the ICE mounting system on the stand, using standard or special vibration-isolating supports (pillows). Longitudinal beams 22 of the ICE fastening system, struts 23 of the protective casing 18, the base housing 24 of the upper support bearing assembly are mounted on the supporting frame of the power frame 25. The inner floor of the test chamber 1 is a soundproof lattice 26 vibro-insulated from the supporting frame 27 of the power frame 25. Air cavity acoustic chamber 1 is ventilated by high-performance supply 28 and exhaust 29 ventilation. The essence of the utility model is illustrated graphically. In FIG. 2 shows a structural fragment of the proposed low-noise ICE test bench, comprising a supporting frame 27, on which a massive metal base 24 of the upper bearing housing assembly is rigidly fixed, which is closed on top by a removable soundproof protective casing 30. The metal bearing housing 31 of the casing 30 is rigidly mounted on the supporting base 24 with screws 32. To attenuate the excitation of structural vibrations and sound, the metal walls of the housing 31 are damped from the inside and outside with a layer of eff projective vibration damping material 33 (or self-adhesive bituminous termopriplavlyaemogo laminate). To the supporting base 24, also by means of screws 32, a frame made of metal pipes 34 of a closed rectangular profile is attached. The internal cavity of the pipes 34 is filled with a loose vibration damping soundproofing substance 35 (for example, quartz sand) or a composite mixture of several loose vibration damping materials, thereby providing low vibrational excitability and vibrational conductivity of the frame structure. Outside frame

sheathed with thin perforated metal panels (frame sheathing) 36. The resulting space between the frame sheathing 36 and the housing 31 is filled with effective porous (fibrous, foamy) sound-absorbing material 37, which significantly reduces the penetration of additional sound waves generated by the stand drive elements and operating equipment in the engine room into the space of the test chamber. In addition, the perforation of the metal panels 36 of the casing 30 reduces the occurrence of sound reflecting effects on the outer surfaces of the casing from incident sound waves in the space of the acoustic chamber 1 and provides additional resonant absorption of sound by the perforated shell of the casing cavity, which improves the quality of vibroacoustic studies.

Practical implementation of the proposed design of a low noise research bench will improve the accuracy and objectivity of the results of bench vibroacoustic tests of internal combustion engines.

Claims (4)

1. A low-noise test bench for internal combustion engines mounted in a muffled anechoic acoustic chamber, comprising, in particular, a support frame mounted vibro-insulated from the floor of the acoustic chamber, on which a massive metal base of the housing of the upper support bearing assembly kinematically connected to the balancer drive shaft is rigidly fixed machines and the drive shaft of the investigated internal combustion engine mounted on the longitudinal beams mounted on the supporting frame, while the housing of the upper support bearing assembly is covered by a protective casing, characterized in that the walls of the casing of the casing from the inside and outside are damped by a layer of vibration-damping material, from the outside the casing shell with the formation of a closed cavity is covered by a supporting frame made of pipes with a closed rectangular profile and fixed to the base of the upper support bearing assembly, the inner cavity of the pipes is filled with a loose vibration damping soundproofing substance and / or composition hydrochloric a mixture of several bulk vibration-damping material, on the walls of the supporting frame fixed walled perforated metal panels, wherein the closed cavity formed between the walls of thin perforated metal panels of the supporting frame and the housing shell is filled with a porous sound absorbing material.  2. The stand according to claim 1, characterized in that the walls of the casing are lined with a layer of self-adhesive and / or hot-melt bituminous laminate.  3. The stand according to claims 1 and 2, characterized in that the internal cavity of the tubes of the frame is filled with quartz sand. 4. A stand according to any one of claims 1 to 3, characterized in that the closed cavity formed between the walls of thin-walled perforated metal panels of the supporting frame and the casing body is filled with superthin basalt fiber, or fiberglass, or open-cell polyurethane foam.