RU2242735C2 - Low-noise acoustic engine test stand - Google Patents

Abstract

FIELD: mechanical engineering; engine testing facilities.

SUBSTANCE: invention relates to diagnostic equipment, namely, to stands for vibroacoustic tests of internal combustion engines. Proposed low-noise acoustic engine test stand contains device for fastening engine on stand made in form of longitudinal and cross guides and vertical posts. Engine fastening device of stand contains additionally easily removable tubular section support posts whose space is filled with loose vibration damping material, for instance, quartz sand, which are diagonally mounted for rigid fixing in slot guides of vertical posts and longitudinal guides. Outer surface of posts is lined with noise-absorbing material with fiberglass cloth transparent to spund or thin protective heat-resistant moisture-and-gas-proof noise transparent foil.

EFFECT: reduced vibration and noise.

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 parameters of ICE, special test benches equipped with various devices and measuring equipment are used.

As the 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 engine, a foundation plate (groove) for installing the ICE and brake in use, a rack for installing and fixing ICE on the foundation a plate, a load brake (hydraulic, electric) for absorbing 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 ICE crankshaft with brake shaft, devices and communications for supplying a cooled lubricating oil, engine coolant to the engine, exhausting the engine exhaust and crankcase gases into the atmosphere, devices and communications for supplying fuel and air to the engine 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 engine parameters (ignition timing , mixture composition, lead angle (beginning of injection), systems providing control and regulation of ICE during testing, remote control with ICE start-up and control bodies placed on it, devices for monitoring engine operation and devices 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.).

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) 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, p.1.

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

In particular, in [1] an example of the use of a semi-muffled acoustic camera from Chrysler (USA) is given, in [2] - an acoustic motor stand of the Central Autopolyon GUP NITSIAMT (Dmitrov, Moscow Region) with a hard sound-reflecting floor, on the groove plate of which special racks fixed investigated ICE. 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 provide transmission of torque or braking torque between the engine and the brake. The end sections of the drive shafts are installed in the bearing units and 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) or chamber walls to the machine room of the stand, equipped with various technological systems and units for ensuring the functioning of the stand.

In [3], the concept of an acoustic motor stand used at the Porsche Research Center (Germany) is presented. 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).

A technical solution is known for designing a test bench for running in and testing an internal combustion engine (RF patent No. 2107175, according to application 96114020) containing a base, a 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 all-metal 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 the selected spatial direction.

A disadvantage of the specialized specialized load stands for conducting vibro-acoustic research and development work on ICEs is the use of ICE fastening devices on a motor stand with high vibrational excitability and vibration conductivity. In particular, the used all-metal racks, lodges, transverse and longitudinal guides, autonomous frame beams provide intensive vibration transfer of dynamic excitation from a working internal combustion engine (from unbalanced forces and moments of inertia) to the mating zones of the groove plate and the chamber floor, causing noise spurious radiation from the floor, which reduces accuracy and objectivity of acoustic measurements. The used all-metal massive elements (longitudinal and transverse guides, racks, autonomous frame beams) are easily excited by the dynamic forces generated by both the internal combustion engine and the drive (brake) units of the stand, vibrate and emit structural noise. In particular, the strong negative effect of parasitic noise radiation of these elements of the stand arises in the resonant modes of bending vibrations of the vertical struts, causing significant dynamic vibratory displacements of the vertical struts, thereby violating the stability of the mechanical oscillating system and the alignment of the mating axes of rotation of the ICE crankshaft and the power take-off shaft of the stand - cardan shaft connecting the crankshaft to the flywheel and clutch assembly with the drive shaft of the upper support bearing la. Violation of the noted kinematic relationship of the mating shafts enhances the "spurious" noise radiation of both the ICE under study and the drive elements of the test bench. These design flaws of the ICE mounting devices on the engine stand make it difficult to conduct high-quality, high-quality vibro-acoustic bench studies of ICE.

The proposed technical solution can significantly eliminate the above disadvantages.

The essence of the invention lies in the fact that in the known low-noise acoustic motor stand, containing, in particular, an ICE mounting device on a stand on which the investigated ICE is mounted, and made in the form of longitudinal and transverse guides and vertical struts, the ICE mounting device on the stand further comprises easily removable supporting posts of tubular section, the cavity of which is filled with loose vibro-damping substance (for example quartz sand), which are diagonally mounted with the possibility of rigid fixation in grooved guides of vertical racks and longitudinal guides, while the outer surface of the racks is lined with sound-absorbing material with a soundproof fiberglass cloth or a thin protective, heat-resistant, moisture-and-gasproof soundproof foil.

The invention is illustrated in the drawings.

Figure 1 shows a completely muffled anechoic acoustic chamber 1, with a drive (brake) balancing asynchronous (or direct current) machine 3 mounted below the floor surface 2 on an autonomous foundation 5 vibration-proof by special springs 4. The inner concrete shell 6 of chamber 1 is installed around the perimeter 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 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 13. The balancing asynchronous machine 3 transmits a 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 rotation area of the drive belt 16 is closed by a protective casing 19. The test object is DV 20 is mounted through the special elastic rubber supports 21 and fastening the mounting brackets 22 to the uprights 23, having the ability to move through the transverse guides 24 and fixed in position. The transverse guides 24, in turn, move freely and are fixed along the longitudinal guides 25. To increase the rigidity and stability of the mechanical structure of the engine mounting device as a whole, the vertical racks 23 are reinforced with closing easily removable diagonal support racks 26. The longitudinal guide rails 25 of the engine mounting device, racks 27 of the protective casing 18, the housing 28 of the upper support bearing assembly are mounted on a supporting power frame 29. The floor of the test chamber 1 is a sound absorber transparently grating 30, isolated from the frame 31 of the carrier frame 29. A power air cavity vented chamber 1 high plenum 32 and exhaust 33 ventilation.

Figures 2 and 3 show a fragment of the construction of the proposed low-noise acoustic motor stand, comprising an ICE fastening device on the stand in the form of two, rigidly mounted by means of a weld on the supporting frame 31, longitudinal guides 25, and two transverse guides 24, which can be moved along the longitudinal guides 25 and be fixed in the required position by means of clamping plates 34 and tightening bolts 35. Four vertical posts 23 are installed on transverse guides 24, I also move which are guided along the transverse rails 24 and are fixed by means of pressure plates 36. Reinforced fastening mounting brackets 22 are mounted on the vertical posts 23 for direct mounting of the internal combustion engine onto a stand through elastic vibration-isolating elements - supports. To increase the bending stiffness, stability of the mechanical system and reduce the vibrational excitability of the design of the engine mounting device on the stand, the vertical posts 23 are reinforced with closed, easily removable diagonal support posts 26 of a closed profile with a hollow section. The organization of a closed (hollow) profile of the support posts 26 (for example, using pipes 37 or metal ducts of square section) subsequently allows filling the internal space of these profiles with effective bulk, foamy or other vibration-damping substance 38 (for example, quartz sand, concrete, integral foam, lead or cast iron) or a combination of these substances in mixtures in predetermined proportions), which provides the required high noise vibration-damping effect. To weaken the occurrence of additional sound-reflecting effects and, as a result, to eliminate distortion of the studied sound field of the test object (ICE) 20, in the space of the acoustic anechoic chamber 1, the outer surfaces of the closing easily removable diagonal support posts 26 are lined from the outside with effective sound-absorbing material 39, the outer surface of which is lined with soundproof fiberglass cloth or a thin protective, heat-resistant, moisture and gas-tight sound-transparent foil 40. Diagonal support with the chutes 26 are connected by a welding seam to the pressure plates 41 and 42, by means of which the diagonal support posts are rigidly fixed and mechanically locked between the longitudinal rails 25 and the vertical posts 23. The groove system for attaching the diagonal support posts 26 using the fixing plates 42, 44 and the pressure screws 43 to the longitudinal rails 25, as well as the presence of a groove 46 in the mounting plate 41, through which the diagonal support racks 26 are fixed on the vertical racks 23 with screws 45, allows targeted You can change the spatial location of the struts 26 depending on the specific location of the elements of the engine mounting device on the stand (transverse rails and vertical racks), followed by rigid fixation of the mounting plates 41, 42 and 44. Rigid fixation of locking easily removable diagonal support racks allows you to limit spatial dynamic movements and bending deformations of vertical struts due to spatial displacements of the ICE under study on supports, as an oscillating solid 6 degrees of freedom.

Practical implementation of the proposed design of a low-noise acoustic motor stand allows you to increase the rigidity and stability of the ICE mount device on the stand, significantly reduce spurious structural noise emitted by both the object under investigation - ICE and vibration-loaded elements of the ICE mount device on the stand and, thus, increase accuracy and objectivity bench vibroacoustic tests of internal combustion engines.

Claims (1)

A low-noise acoustic motor stand, including, in particular, an ICE mounting device on a stand on which the investigated ICE is mounted, and made in the form of longitudinal and transverse guides and vertical struts, characterized in that the ICE mounting device on the stand additionally contains easily removable support columns of tubular section the cavity of which is filled with a loose vibrodamping substance (for example, quartz sand), which are diagonally mounted with the possibility of rigid fixation in the grooved guides vertically racks and longitudinal guides, while the outer surface of the racks is lined with sound-absorbing material with a soundproof fiberglass fabric or a thin protective, heat-resistant, moisture-proof, soundproof transparent foil.

Images