SU1638324A1 - Pliable member for lowering noise of pulsating gas flow and method of making same - Google Patents

Abstract

The invention relates to mechanical engineering and allows for effective volumetric compressibility above air compliance and increasing the efficiency of noise-attenuating properties. The element contains pipe 1, body 2 perforated pipe 3, pipe 4 and hermetic compliant elements 5 placed in chamber 6 between the walls of body 2 and pipe 3 Element 5 contains an airtight shell of an airtight material from which air is partially or completely removed and in which a pre-deformed elastic structure is placed air pressure oscillations during air suction are transmitted through pipe 1 and pipe 3 and through its openings enter chamber 6 in the event of an increase in pressure, air in chamber 6 and the elements 5 are compressed. The change in volume is compensated by air flowing into chamber 6. When the pressure decreases, the volume of elements 5 and air in chamber 6, the excess air is pushed out. The more intense the exchange of air, the less oscillation is transmitted to the nozzle 4 and the atmosphere, and the more efficient the process of sound attenuation is 2c and 5pf files, 10 il sl C

Description

Fy

FIELD OF THE INVENTION The invention relates to mechanical engineering, in particular, engine-building, namely to intake and exhaust systems, primarily an internal combustion engine.

The purpose of the invention is to provide an effective volumetric liquefaction higher than air compliance and an increase in the efficiency of noise suppressing properties.

Fig. 1 shows a variant of the device for damping intake noise with hermetic compliant elements; FIG. 2 shows a version of a hermetically hermetic element with a deformed elastic structure made of a porous material with open pores; fig. 3 - the same, with a deformed elastic structure in the form of a soft, pre-compressed spring; Fig. 4 shows a hermetically hermetic element in its initial state; Fig. 5 is the same in the compressed state; in Fig. 6, a non-perforated porous element (material); 7 - deformed porous element (material); on Fig - the same, in the bag of impermeable material; figure 9 - punch with a flexible clamp; in fig. 10 is a variant of hermetically compliant element of ellipsoid form with a deformed elastic structure made of a porous material with open pores.

The device (Fig. 1) contains a pipe 1 connected to a source of oscillations (engine intake cylinders), a housing 2, a perforated pipe 3 placed inside the housing, a pipe 4 through which air is supplied from the atmosphere to the intake system, and hermetic compliant elements 5 with an effective volume compressibility, greater air compressibility, placed in the chamber 6 between the walls of the housing 2 and the perforated pipe 3.

The hermetic compliant element 5 (FIG. 2) contains a hermetic sheath 7 made of an airtight material from which air is partially or completely removed and in which a pre-deformed elastic structure is placed, or of a porous material with open pores 8 (figure 2), or in the form of a sponge of interwoven elastic threads, for example, metal or synthetic, or, for example, of a pre-compressed soft spring 9 (FIG. 3).

Completing the sealed compliant element 5 are an undeformed porous element 10 (Fig. 6) and a bag 11 of an airtight material. Equipment for the manufacture of an element includes a table 12, a rigid punch 13, a punch 14 with a flexible clamp 15 and a welding head 16.

In the device (FIG. 1), the sound attenuation is performed as follows.

Air pressure oscillations arising from the engine cylinders during air suction are transmitted through the pipe 1 and the perforated pipe 3, through its openings enter the chamber 6 formed

the walls of the housing 2 and the perforated pipe 3.

In the event of an increase in pressure (Ap 0), the air in chamber 6 and compliant elements 5 are compressed by the action of increased

pressure. The picture of the deformation of the elements 5 is illustrated in Fig. 5, where the solid line shows the malleable element 5 after the deformation, the dotted one before the deformation. The total change in the volume of air in chamber 6 before the pressure rises. and elements 5 equals

AV Home + AV3n, (1)

where D VBOSA air volume change; - change in the volume of elements 5.

Change in air volume

A / Air Uvod Ar Rvoed (- V3) (2)

where N / air is the volume of air in chamber 6;

/ e - the volume of elements 5:

VK3M - chamber volume 6;

AZOZD air compressibility, which characterizes the relative change in air volume with increasing pressure,

AV

raised

Ar

(3)

40 Changing the volume of elements 5

V3n V Ap, (4)

where is the relative compressibility of 5,

five

ft

one

V

, el

DZhzl AR

(five)

where DN.el is the deformation of element 5 after the pressure Ap is increased,

0АУ1эль Уъл-Угэл1 (6)

where / 1зл - the volume of one element 5 to the deformation;

Vaan - the volume of the same element 5 after deformation.

5 From formulas (1), (2) and (4) it follows that

(1 ") VKaM Ar + $ LAUKam AR

(7)

where a is the relative volume occupied by the elements 5 before deformation

d Uz

Further from formula (5) it follows that

DU / 8v0zd VKaM Lr + + "Ozel-Ayuzd kam -Dr. (9)

The first term in expression (9) defines the change in the volume of air in chamber 6 in the absence of elements 5 (Wel 0 or a 0); the second term is an additional volume change due to the presence of compliant elements 5.

The change in volume L V is compensated by air flowing into the volume of chamber 6 through the perforations. When the pressure decreases (D p 0), the volume of the elements 5 and the air in the chamber 6 increases and the air is pushed out of the chamber 6. Thus, the air is exchanged between the chamber

6 and a branch pipe 1. The more intense this exchange (the greater the fluctuations of D V with the same changes in pressure D p). the less oscillation is transmitted to the nozzle 4 and to the atmosphere, the more effective the process of sound attenuation.

If the effective volume compressibility of the elements 5 () is more air compliance () and the elements occupy a sufficiently large volume in chamber 6, then the volume in the latter filled with elements 5, with the same pressure fluctuations, increases compared to the similar design without ductile elements 5. Therefore, for increasing the efficiency of sound attenuation by periodically exchanging air between the noisy area and compliant elements 5, their effective volumetric compressibility choose greater air compressibility.

Sealed malleable element 5 (figure 2) to reduce the transmission of airborne noise works as follows.

In the absence of pressure fluctuations in the environment surrounding the element 5 on the shell

7, the external pressure forces Rn (Fig. 4), the elastic forces from the deformed porous element 8 (Upr) and the elastic forces from expansion of the sheath 7 act. These forces are still in equilibrium.

When a pressure oscillation (D p) occurs at the walls of the element 5, the equilibrium is disturbed and the element 5, for example, at D r 0, is compressed. For well compliant shells 7, the amount of deformation of element 5 is determined mainly by the elasticity of the inner contents of the shell 7. No matter how soft the porous element 8 is.

if no air is removed from the hermetic shell 7, the deformation of the element 8 will not be greater than the deformation of the equivalent hermetic volume filled with air, 5 i.e. element flexibility 5

(ten)

there will be no more pliability of an equivalent element filled with air

(/% cu.)

In order to increase the compliance of element 5, from it partially or completely

air is removed. In this case, the compliance of the element 5 is determined mainly by the elasticity of the porous material 8 (or another deformed elastic structure placed inside the shell 7).

By selecting the elasticity of the porous material 8 in the deformed state, the lower the elasticity of the air, is that the effective compliance of the element 5 becomes greater than the elasticity of the equivalent closed volume of air.

Accordingly, the volumetric strain of the element 5 increases with pressure fluctuations and the method of reducing airborne noise is effectively implemented.

The deformable elastic structure placed in the hermetic casing 7 can be made either of porous material with open pores 8 (so that air can be removed from them), or

a kind of matted metal or synthetic elastic threads interwoven in the form of a sponge, or in the form of a soft deformed spring 9, or a mesh of such springs. The dimensions of the undeformed elastic porous element 10 (Fig. 6) are chosen such that after compression to the required size, the elastic force of the deformable elastic structure is equal to the external air pressure forces.

For example, if necessary, get

effective compressibility of the hermetic compliant element 5 10 / Draft (ten times higher compressibility of air) for a porous isotropic material it is necessary to select a porous material with a bulk modulus of elasticity

K Kovd Oh 105N / m2 REL

 104N / m2.

(eleven)

The undeformed dimensions (volume V) of the porous material 10 must be chosen.

V

Kvaz K

where Wel is the required size of the hermetic compliant element 5.

After compressing to Van, the elastic force of the porous material 10 will balance the elastic forces of the air.

The method of manufacturing the sealed, water-resistant element 5 is carried out as follows.

The elastic structure (porous element 10) is compressed with a rigid punch 13 on the table 12 to a size smaller than the required volume of the hermetic compliant element 5 (FIG. 7), placing the compressed element 10 in an unsealed enclosure in the form of an air-permeable material bag 11 (Fig.8). The dimensions of the bag 11 are larger than the dimensions of the porous element 10. This ensures minimum elastic forces from the shell when the element 10 is expanded after the air has been removed. In addition, allowances for subsequent welding or gluing are provided for sealing. Next, the element is crimped by the punch 14c with a flexible bottom 15. to remove air from the porous element 10, and the element 5 is sealed in a crimped state, for example by welding the walls of the shell 7 with a welding head 16. The final view of the element is shown in Fig. 10.

Thus, the required degree of air removal without special fittings for air pumping, low weight and inertia of the shell 7 and, ultimately, high noise suppression properties of the sealed compliant element 5.

at

FIG. 2

five

10 15 20 25 30 35

40

Claims (6)

1. A malleable element for reducing the noise of a pulsating gas stream, containing a sealed closed volume, having an elastic filler and limited by a flexible shell, characterized in that, in order to ensure effective volumetric compressibility above air compliance, the sealed closed volume is evacuated, and the filler is in the form deformed elastic construction. 2. The element according to claim 1, wherein that, as a deformed elastic structure, a porous material with open pores was used. An element according to claim 1, characterized in that a sponge of interlaced elastic threads is used as the deformed elastic structure. 4. An element according to Clause 3, characterized in that the elastic threads are made of metal. 5.Item of item 3, characterized in that the elastic threads are made of synthetic An element according to claim 1, characterized in that a soft, pre-compressed spring is used as a deformed elastic structure. T. A method of manufacturing a compliant element to reduce the noise of a pulsating gas stream by sealing a flexible shell and filling it with an elastic filler, characterized in that, in order to increase the efficiency of sound-attenuating properties, the elastic filler, made in the form of a deformed elastic structure, is placed in an unsealed flexible the shell is compressed with the latter before the air is removed and the shell is sealed in a compressed state. Rig.Z L /////////////////// 7 / Ј eight Ј Matt Sh 1GV  LR -d + Hd t ZC8C9l 9 Mf U /////// // //////////, Ouf FIG. ten AND 15 /