RU23919U1 - NOISE-PROTECTING COVER OF THE VEHICLE INNER COMBUSTION OF THE VEHICLE - Google Patents

Abstract

1. Noise-insulating casing of an internal combustion engine of a vehicle, comprising a supporting decorative shell made of dense polymeric material, the inner surface of which is provided with stiffeners and a sound-absorbing panel made of porous material coated on the outside with stiff ribs, characterized by the fact that at least at least on the part of the inner surfaces of the shell bounded by stiffeners, intermediate panels are mounted, the structure of which includes covers a layer of dense viscoelastic vibration damping material and a layer of porous sound-absorbing material, while the surfaces of the dense layers of the intermediate adhesive panels are connected to the opposing surfaces of the shell, and on the opposite side, the intermediate panels, on the side of the porous layer, are adhesively connected to the opposing sound-absorbing panel of the casing, in addition, between air gaps are formed by the counter free lateral ends of the porous layers of the intermediate panels. 2. The casing according to claim 1, characterized in that the layers of a dense viscoelastic vibration damping material of the intermediate panels are mounted with the possibility of tight gapless contact with the stiffeners, while the height of the stiffening ribs corresponds to the thickness of the layer of a dense viscoelastic vibration damping material of the intermediate panels. The casing according to claims 1 and 2, characterized in that the intermediate panels are connected to the shell and the sound-absorbing panel by means of a sticky adhesive joint. The casing according to claims 1 and 2, characterized in that the intermediate panels are connected to the shell and sound absorption�

Description

MPK7R02V77 / 13

F02F 7/00

G10K 11/16

NOISE-INSULATING COVER OF THE INTERNAL COMBUSTION ENGINE

VEHICLE

The utility model relates to the field of mechanical engineering, in particular transport mechanical engineering, and is a design of a noise-damping decorative casing of the upper part of an internal combustion engine (hereinafter ICE) of a vehicle.

To enhance the aesthetic characteristics of the engine compartment of the vehicle, i.e. improving the appearance due to the original design, as well as for targeted thermal insulation of individual areas of the engine compartment or to provide increased noise absorption in the local areas of the internal combustion engine in order to ensure compliance with the standards for external and internal noise of the vehicle and improve its consumer qualities by increasing acoustic comfort in the cab (passenger compartment) of the vehicle, the design of special housings covering the upper noise-active part of the internal combustion engine is quite widely used, ennyh as the outer carrier shell (panel) of a resin material (polyamide, polypropylene, etc.) and lined inside respective porous (fiber, foam) absorbing material. To a greater extent, such a casing attenuates the noise generated by the gas distribution mechanism of the internal combustion engine. The fastening of such a casing is removable and is carried out to the external surfaces of the corresponding parts of the ICE body and mounted auxiliary units and ICE systems, which are known to be subject to intense vibrations during the implementation of work processes that take place directly in the ICE. Accordingly, being attached to various areas of the engine and / or various engine components (for example, to the valve cover, intake system receiver, cylinder head, etc.), which make intense oscillatory movements relative to each other, different in spectral composition, amplitude and phase ratio .

the casing (its supporting shell) is loaded with the corresponding force and kinematic excitation, as a result of which its walls perform intense free and forced vibrations, bending deformations, turning it (the casing) into an oscillating sound-emitting diaphragm (shell). Especially dangerous are the vibrations of the casing of the casing at resonant frequencies of oscillations, when the frequencies of dynamic excitations from the internal combustion engine supplied to the casing coincide with one of the frequencies (or multiples of one or more frequencies) of the natural bending vibrations of the casing of the casing, which leads to an enhanced process of sound emission, and in some cases, and to dynamic destruction of the casing structure.

In order to mitigate such an adverse effect on the excitation of the bearing structure of the casing shell through solid transmission paths (fixing ties), the casing is attached to the internal combustion engine in most cases using intermediate elastic vibration-isolating elements (usually rubber-metal bushings) that weaken the transmission of vibrational energy transmitted from the ICE case (ICE auxiliary and mounted units) to the shell structure of the casing, see, for example, US Patent No. 4027644, IPC F02B 77/00, 1977. However, such a constructive solution is not always effective enough and has a number of significant drawbacks.

Firstly, the use of elastic vibration-insulated casing fastening, along with the weakening of transmission at medium and high frequencies of vibrational excitation, leads to the indispensable low-frequency resonance of the oscillating system as an oscillating solid body in an elastic connection (the mass of the casing mounted on the spring), with corresponding radiation amplification low frequency sound (noise).

Secondly, the use of rubber vibration-insulating bushings of the casing in the hot zones of ICE requires, on the one hand, the use of expensive heat-resistant rubbers, and on the other hand, it is certainly associated with a gradual loss of the elastic vibration-damping characteristics of the rubber elements due to the prolonged exposure to high temperatures during long-term operation.

In this case, the elastic and damping characteristics of rubber elements are also significantly deteriorated. An even greater degree on the durability of rubber vibration insulating sleeves is influenced by alternating temperature loads associated with their periodic heating and cooling during operation in the winter season.

The prototype of the invention is described in the collection of reports of the 31st ISATA International Symposium 98 on automotive technology and automation, held in Germany, Dusseldorf, June 2 ... 5, 1998, see Dr.-Ph. Thome, Rieter Automotive France SA Top Engine Cover: A Part of a comprehensive Noise Reduction Sistem, 98 SAP 068, c. 287 ... 297 (attached).

The prototype describes a decorative ICE casing serving as a silencer of the upper part of the ICE casing, see FIG. 7-8. The casing contains a supporting decorative panel made of dense polymeric material, equipped with internal stiffening ribs, which is attached to the body parts of the engine (valve cover and receiver) with removable threaded parts (hardware) and contains an internal porous sound-absorbing layer of fibrous or foam material connected to the vertices of the ribs of the ribs the supporting panel with a thermo-adhesive or sticky adhesive joint (mechanical holders of the porous sound-absorbing layer are not excluded), and also contains vibration-isolating e bushings in the areas of fastening the casing to the internal combustion engine.

In the selected prototype there are problems that have already been noted above. In particular, the sound-absorbing layer of the casing, without having a sufficiently high coefficient of losses due to vibrational damping of structures, practically does not hinder the possibility of low-frequency bending resonances of the elastically mounted rigid supporting structure of the casing, which leads to the corresponding generation of intense low-frequency sound by this structure.

The technical problem in the proposed device is solved by eliminating the use of vibration-isolating elastic support bonds of the casing, and using, in a certain way, vibration-damping and sound-absorbing panels mounted on its inner surface, the structure, physicomechanical characteristics and location of which are selected in a certain way.

The essence of the utility model lies in the fact that in the well-known ICE casing of a vehicle containing a supporting decorative shell made of dense polymeric material, which is provided with internal stiffening ribs oriented in certain directions and placed on the stiffening ribs side, a sound-absorbing panel made of porous material lined on the outside with a thin soundproof transparent film, at least on the part of the inner surfaces of the shell, limited by the ribs, mounted intermediate Aneli structure which, in cross section, dense viscoelastic vklyuchaetsloy

vibration damping material, conjugated to the surface of the decorative shell, and in turn conjugated to it on the other side of the layer of porous sound-absorbing material, while the dense vibration-damping layers of the intermediate adhesive panels are connected to the shell surfaces, and on the opposite side, the intermediate panels are glued to the surfaces of the sound-absorbing layers with a sound-absorbing panel of the casing, in addition, air is formed between the opposing free end faces of the intermediate panels clearance.

In a preferred embodiment, the height of the ribs of the shell casing corresponds to the thickness of the layer of a dense viscoelastic vibration damping material of the intermediate panel.

Various structural options for mounting intermediate panels are possible. In particular, the intermediate panels can be connected to the shell and the sound-absorbing panel by means of a sticky adhesive joint, or by means of a thermal adhesive.

The essence of the utility model is illustrated in the drawings, where:

- figure 1 shows the inventive casing design, view from the internal combustion engine;

- figure 2 shows a cross section of the casing along aa, figure 1;

-Fig. 3 shows a wiring diagram of the location and connection of the intermediate panels and the sound-absorbing panel with the bearing shell of the casing;

- figure 4 shows the test results of samples of sound-absorbing material of the casing in the research installation of the Kundt pipe, with measurement data of the normal coefficient of sound absorption of sound by the method of an acoustic interferometer, where:

Sample No. 1 - a single-layer self-adhesive sound-absorbing open-cell polyurethane foam (PUF) with a thickness of 12 mm, lined with an external thin sound-transparent aluminized film;

- sample No. 2 - a structure of a two-layer sheet of self-adhesive sound-absorbing material, including two identical samples of material No. 1, interconnected by a sticky adhesive layer;

Sample No. 3 - a structure of a two-layer sheet of self-adhesive sound-absorbing material of sample No. 2, modified by making air cavities (gaps) in it in the form of alternating slotted grooves 40 mm wide and 12 mm deep.

figure 5 shows the results of measurements of the reverberation coefficient of sound absorption of the above samples by the chamber method (research facility Cab Alpha) in a diffuse sound field.

The casing, FIGS. 1 and 2, two vehicles, contains a supporting decorative shell 1 made of a dense polymeric material, which is provided with internal ribs 2 for stiffness and placed on the side of the stiffeners, a sound-absorbing panel 3 made of porous material, lined with a thin, translucent material protective film 4. At least on a part of the intercostal inner surfaces 5, Fig. 3, of the shell 1 bounded by stiffening ribs 2, intermediate panels 6 are mounted, the structure of which, in cross section includes a layer 7 of a dense viscoelastic vibration damping material, conjugated to the surface of the decorative shell and the layer 8 of the porous sound-absorbing material conjugated thereto, on the other hand. At the same time, the dense layers 7 of the intermediate panels are adhesively connected to the surfaces 5 of the shell 1, and on the opposite side, the intermediate panels 6 are adhesively connected to the sound-absorbing panel 3 of the casing. Between the opposing free end faces 9 of the intermediate panels 6, air gaps are formed 10. In a preferred embodiment, the height of the stiffening ribs 2 corresponds to the thickness of the layer 7 of the dense viscoelastic vibration damping material of the intermediate panel. To increase the rigidity of the decorative shell, it is desirable to mount layers of a dense viscoelastic vibration-damping material of the intermediate panels with the possibility of tight, gapless contact (in the spacer) with

stiffening ribs (in the intercostal space). In this case, it is desirable that the height of the ribs corresponds to the thickness of the layer of dense viscoelastic vibro-damping material of the intermediate panels, thus providing an effective surface of adhesive adhesion (closure) and the deformation transformation of the vibrational energy of the decorative shell into thermal energy dissipated in the viscoelastic layer of the damping material.

Various structural options for mounting the intermediate panels 6 are possible. In particular, they can be mounted by means of a layer 11 of sticky adhesive or thermo-adhesive material.

The decorative casing is fastened to the surfaces of the corresponding parts of the ICE case and mounted auxiliary units and ICE systems, which are known to be subject to intense vibrations during the implementation of work processes occurring directly in the ICE. Accordingly, being attached to various areas of the engine and / or various engine components (for example, to the valve cover, intake system receiver, cylinder head, etc.), which make intense oscillatory movements relative to each other, different in spectral composition, amplitude and phase ratio , the casing (supporting shell) is loaded with the corresponding force and kinematic excitation. As a result of this, its walls make intense free and forced vibrations, bending deformations, turning it (the casing) into an oscillating sound-emitting diaphragm (shell). Especially dangerous are the vibrations of the carrier panel 1 (shell) of the casing at the resonant frequencies of bending vibrations, when the frequencies of dynamic excitations supplied to the shell coincide with one of the frequencies (or multiples of one or more frequencies) of the natural bending vibrations of the casing panel, because this leads to an enhanced resonant process of sound emission into the environment, and in some cases to dynamic destruction of the casing structure.

The noise-insulating efficiency of the casing can be improved both due to the use of a multilayer noise-damping design of panels in which each layer has a purposeful function of amplifying the elements of noise isolation (vibration damping, sound absorption), and due to the message to the bearing structure of the casing of the shell of a higher value of the loss modulus E | a, 6

where E is Young's modulus, is the loss coefficient (internal friction) of the shell material, due to the connection of vibration damping panels having a high loss coefficient to it. The larger the loss modulus of Ec, the higher the soundproof quality of the casing. The bending deformations of the shell 1 of the casing give the corresponding bending spatial vibratory displacements to the ribs 2, and with them deform (bend, compress, stretch) the structure of the elastically deformable layers 7 of the dense viscoelastic layer of the vibration-damping material of the intermediate panels 6, while performing additional deformation work, spending the input vibrational energy and, thus, significantly enhance the process of converting the energy (work) of elastic deformable structures of the shell 1 into energy nyh deformation vibration-damping layers 7 with an appropriate additional conversion of mechanical energy into thermal energy dissipated in layers 7. Thus, the attenuated noise emitted directly vibrating the carrier shell casing 1.

In turn, the function of absorbing sound energy emitted by the upper part of the ICE case, located under the casing, is performed by the porous sound-absorbing layers 8 of the intermediate panels 6 and the sound-absorbing panel 3, which consists entirely of porous sound-absorbing material (except for the protective film 4).

To enhance the absorption efficiency of sound energy, especially in the low frequency region of the sound spectrum emitted by the upper part of the ICE case, air gaps 10 are formed between the opposing free end planes 9 of the intermediate panels 6.

The pairing of the sound-absorbing panel 3 with the shell 1 through intermediate elements - the panel 6, with the formation between the free side ends 9 of the air gaps 10, allows not only to increase the thickness of the sound-absorbing structure under the shell 1 of the casing, but also causes a soft vibration-damping compression of the bearing shell 1 of the casing to its surfaces pairing with the body parts of the internal combustion engine. The formation of air gaps 10 in the porous sound-absorbing structure of the casing panels allows you to shift the effective area of sound absorption in the low- and mid-frequency ranges, and increase the sound absorption coefficient in absolute value.

On the two sides, the sound-absorbing structure of panels 3 and 6 of a porous fibrous or foam material is protected from the adverse environmental effects by a thin sound-transparent film, for example, fabric like malinflise, aluminized foil or urethane film 4.

Practical implementation of the proposed device allows you to:

-to ensure compactness of the casing, as the use of high stiffening ribs 2 is not required to provide the specified bending stiffness of the outer decorative shell 1, to weaken its vibrational excitability, since the space between the ribs 2 is filled with a layer 7 of dense vibration-damping viscoelastic material that increases the bending stiffness of the shell 1 and additionally dissipates vibrational energy, which allows effectively suppress vibration excitation and sound emission by shell 1;

-to ensure effective adhesion of the sound-absorbing layer of the panel 3 over the maximum interface with the vibration damping sheath 1, which, in some cases, allows the use of a less expensive, with less adhesion, adhesive layer 11 (which is difficult for the use of dimensional protruding stiffeners);

- introduce additional sound-absorbing gaskets (intermediate panels 6) into the space between the sound-absorbing panel 3 and the shell 1 of the casing, providing higher sound absorption in the low- and mid-frequency range, due to the removal of panel 3 from the internal sound-reflecting surface of the shell 1 and additional sound absorption by free end the surfaces 9 of the intermediate panels 6;

- use the shell 1 of the casing of a cheaper (e.g. polypropylene) polymer material, and not, for example, expensive polyamide, because high vibrational excitation of the thin polypropylene panel 1 (shell) can be effectively suppressed by the claimed design of structural damping (vibration damping layers 7 in the strut closing intercostal space).

As the experiments showed, see Figs. 4 and 5, the use of the proposed multilayer sound-absorbing structure of the casing made it possible to significantly increase the normal sound absorption coefficient in the dominant frequency range of the noise emission of the internal combustion engine of 400 ... 1250 Hz (25 ... 60%), t .e. more than 3 times, in comparison with standard sound-absorbing material from a single-layer open-cell foam

coated with a layer of thin translucent aluminized film (see figure 4, sample No. 2). The formation of additional air cavities 7 between the free ends of the strips 5 makes it possible to improve sound absorption in the frequency range covered by 1/3 octaves with centers of 400 ... 630 Hz and, thus, to ensure the construction of a wider frequency domain of effective noise absorption (see. 4, sample No. 3).

Carrying out similar experiments with a multilayer sound-absorbing structure by evaluating the reverberation coefficient of sound absorption by the chamber method (see Fig. 5), qualitatively and quantitatively confirmed the effects of improving sound absorption in the dominant frequency range of 400 ... 1000 Hz and showed the possibility of increasing diffuse sound absorption when performing air cavities in the sound-absorbing structure of the lining of the engine cover (see figure 5, sample No. 3) ..

The effectiveness of the application of the claimed engine cover is also confirmed by the results of road tests of the VAZ-21113 car, equipped with a 4-cylinder in-line 16-valve engine with a working volume of 1.5 liters, of the VAZ-2112 model, on which the claimed soundproof cover was installed instead of the standard one used in serial production cars AVTOVAZ JSC. As shown by measurements of the general levels of external noise of the car in intensive acceleration mode in 2nd and 3rd gears in accordance with the method of UNECE Rule 51-02 and GOST R.41.51-99, the overall level of external noise of the car with the inventive soundproof casing installed by 0.5 dBA, which allowed the test sample of the car to fully comply with the requirements of international (UNECE) and national standards (GOST RF).

Claims (4)

1. Noise-insulating casing of an internal combustion engine of a vehicle, comprising a supporting decorative shell made of dense polymeric material, the inner surface of which is provided with stiffeners and a sound-absorbing panel made of porous material coated on the outside with stiff ribs, characterized by the fact that at least at least on the part of the inner surfaces of the shell bounded by stiffeners, intermediate panels are mounted, the structure of which includes covers a layer of dense viscoelastic vibration damping material and a layer of porous sound-absorbing material, while the surfaces of the dense layers of the intermediate adhesive panels are connected to the opposing surfaces of the shell, and on the opposite side, the intermediate panels, on the side of the porous layer, are adhesively connected to the opposing sound-absorbing panel of the casing, in addition, between Oncoming free lateral ends of the porous layers of the intermediate panels formed air gaps.  2. The casing according to claim 1, characterized in that the layers of a dense viscoelastic vibration damping material of the intermediate panels are mounted with the possibility of dense gapless contact with the stiffeners, while the height of the stiffening ribs corresponds to the thickness of the layer of a dense viscoelastic vibrodamping material of the intermediate panels.  3. The casing according to claims 1 and 2, characterized in that the intermediate panels are connected to the shell and the sound-absorbing panel by means of a sticky adhesive connection. 4. The casing according to claims 1 and 2, characterized in that the intermediate panels are connected to the shell and the sound-absorbing panel by means of a thermo-adhesive substance.