CN102562381A - Double-frequency air inlet resonant cavity of automotive engine air inlet system - Google Patents

Abstract

The invention relates to a double-frequency air inlet resonant cavity of an automotive engine air inlet system. The air inlet resonant cavity is formed by serially connecting a resonant cavity A and a resonant cavity B; the resonant cavity A consists of a connecting pipe A and a cavity A; the resonant cavity B consists of a connecting pipe B and a cavity B; and the cavity A is connected with an air inlet pipeline through the connecting pipe A and connected with the cavity B through the connecting pipe B. The correlation of the volume of each resonant cavity, the length of each connecting pipe, the section area and the working frequency can be calculated through a formula; and the resonant cavity can eliminate the air inlet noise of two different frequencies, and can be formed by using a set of mold.

Description

Automotive engine air intake system bifrequency air inlet resonant cavity

Technical field

The present invention relates to the NVH technical field, particularly a kind of device that reduces the automotive air intake System noise.

Background technique

Along with national automobile strict day by day through legislations for noise, and user vehicle is to the raising of NVH performance requirement, and automobile NVH control technique seems more and more important.Induction noise is as one of main contribution source of automobile noise, and reducing induction noise is the key factor of can not ignore in the car load development process.

The resonant cavity that exists at present can only reduce the duct noise of a frequency, the effect frequency of resonant cavity only with connecting tube length l, the connecting tube sectional area S of resonant cavity _c, volume V is relevant, forefathers have drawn resonant cavity effect frequency calculating formula through derivation:

(c represents the velocity of sound, is 344m/s under the normal temperature) is widely used in the gas handling system development process at present.

But in the NVH of automotive air intake system development process; The noise that runs into two different frequencies through regular meeting need be subdued; At this moment normally the diverse location on the pipeline of gas handling system increases by two helmholtz resonance chambeies to reduce the noise of these two frequencies; But there is the defective of two aspects in this mode, is the restriction that receives the engine compartment space in the gas handling system design process on the one hand, sometimes has only the arrangement space in a helmholtz resonance chamber; In addition on the one hand, if gas handling system will be produced in batches, two helmholtz resonance chambeies need two cover injection moulds, and cost is too high.

Summary of the invention

The objective of the invention is singlely and to produce cost in batches high and propose a kind of automotive engine air intake system bifrequency air inlet resonant cavity to helmholtz resonance chamber respective frequencies, they can corresponding two different frequencies, and cost is lower.

The technological scheme that the present invention adopts is following:

A kind of automotive engine air intake system bifrequency air inlet resonant cavity; It is characterized in that: constitute by two independent resonant cavity A resonant cavity B series connection; The connecting tube of hereinafter claiming resonant cavity A is connecting tube A; The cavity of resonant cavity A is cavity A, and the connecting tube of resonant cavity B is connecting tube B, and the cavity of resonant cavity B is cavity B.Cavity A links to each other with admission line through connecting tube A, links to each other with cavity B through connecting tube B.If the connecting tube A length of resonant cavity A is l ₁, the sectional area of connecting tube A does

Cavity A volume is V ₁, the connecting tube B length of resonant cavity B is l ₂, connecting tube B sectional area does

Cavity B volume is V ₂, the formula of two effect frequencies of bifrequency air inlet resonant cavity is following:

$f_1=\frac{\sqrt{(\frac{c^2{s}_{c_1}(v_1+v_2)}{l_{c_1}{v}_1{v}_2}+\frac{c^2{s}_{c_2}}{l_{c_2}{v}_2})+{(\frac{c^2{s}_{c_1}(v_1+v_2)}{l_{c_1}{v}_1{v}_2}-\frac{c^2{s}_{c_2}}{l_{c_2}{v}_2})}^2+4\frac{c^4{s}_{c1}{s}_{c_2}}{l_{c_1}{l}_{c_2}{v_2}^2}}}{2\mathrm{\π}\sqrt{2}}$

$f_2=\frac{\sqrt{(\frac{c^2{s}_{c_1}(v_1+v_2)}{l_{c_1}{v}_1{v}_2}+\frac{c^2{s}_{c_2}}{l_{c_2}{v}_2})+{(\frac{c^2{s}_{c_1}(v_1+v_2)}{l_{c_1}{v}_1{v}_2}-\frac{c^2{s}_{c_2}}{l_{c_2}{v}_2})}^2+4\frac{c^4{s}_{c1}{s}_{c_2}}{l_{c_1}{l}_{c_2}{v_2}^2}}}{2\mathrm{\π}\sqrt{2}}$

C represents the velocity of sound, is 344m/s under the normal temperature.

This device is through working on the pipeline that is connected gas handling system, and the correlation of the volume of resonant cavity, connecting tube length, sectional area, frequency of okperation can convert through above formula.

The structure that the present invention adopted can reach the purpose that reduces by two different frequency induction noises.Simultaneously, the structure of this two resonant cavitys series connection can solve the problem that the part vehicle runs on spatial arrangement.In addition, adopt bifrequency air inlet resonant cavity, only need open a secondary mould, number of molds can reduce half the.According to the fixed form of trunk line, can also reduce one sometimes and be connected and fixed the part of usefulness with trunk line, can reduce cost greatly.This resonant cavity can be regarded a binary free oscillating system as, can be applied in above the gas handling system performance development.

Description of drawings

The structural representation of Fig. 1 bifrequency air inlet resonant cavity;

Fig. 2 bifrequency air inlet resonant cavity mechanical model;

Fig. 3 bifrequency air inlet resonant cavity transmission loss test result.

Among the figure: 1-gas handling system pipeline 2-connecting tube A 3-cavity A 4-connecting tube B 5-cavity B 6-gas handling system (air-strainer)

Embodiment

Apparatus of the present invention are made up of two resonant cavity series connection; As shown in Figure 1; Be that 2-connecting tube A, 3-cavity A and 4-connecting tube B, 5-cavity B form a resonant cavity respectively; 4-connecting tube B links to each other with 3-cavity A promptly that two resonant cavitys series connection have constituted this device then, this device through with gas handling system pipeline 1, gas handling system 6 (air-strainer) thus make up and be applied on the automobile.The effect frequency of this device only with length, the sectional area of connecting tube A, B, the volume of cavity A, B is relevant, in practical applications, after relevant parameter changes, can convert according to formula (19), (20), thereby obtain the result that needs.This device is connected and then can reduces by two different frequency induction noises on the gas handling system, and link position can be in the arbitrary position of gas handling system pipeline, and Placement can design voluntarily, but must guarantee the permission of sealing and design space.

The working principle of bifrequency intake silencer is following: when incident acoustic wave is propagated in the gas handling system pipeline; Acoustic wave segment can get into bifrequency air inlet resonant cavity; After running into the border, the sound wave that enters into resonant cavity A through connecting tube A can be reflected back; But because the existence of connecting tube B is arranged, sound wave also can continue to propagate, and arrives resonant cavity B; Getting into behind the resonant cavity B sound wave runs into the border and can reflect back equally; Will produce two reflective sound waves of returning at the jointing of gas handling system pipeline and bifrequency air inlet resonant cavity like this from the resonant cavity internal reflection, when reflective sound wave opposite with the incident acoustic wave phase place, thereby at this moment reflected wave will cause the reduction of incoming wave amplitude with the node that the identical incoming wave of self frequency is offset the formation acoustic pressure.If regard the air in the connecting tube as quality, resonant cavity is regarded spring as, and we can also regard this system as a binary free oscillating system, supposes that the air quality of connecting tube A the inside is m ₁, the rigidity of cavity A is k ₁, connecting tube B the inside air quality be m ₂, the rigidity of cavity B is k ₁, can obtain mechanical model Fig. 2, when this system resonance, just can eliminate the vibration of certain two frequency sound wave in the pipeline.

Relation between the natural frequency of coupled system and each parameter of bifrequency air inlet resonant cavity can draw through the derivation of equation:

Because the gaseous mass in the connecting tube: $M_A=\frac{l_c}{S_c}\left[1\right]---\left(1\right)$

In the formula, S _cAnd l _cBe respectively connecting tube sectional area and length;

The acoustic capacitance resistance: $C_c=\frac{V}{C^2}\left[1\right]---\left(2\right)$

V represents the resonant cavity volume in the formula, and C is a constant, represents the velocity of sound;

The natural frequency of single degree of freedom system: $f=\frac{1}{2\mathrm{\π}}\sqrt{\frac{k}{m}}---\left(3\right)$

The frequency of noise elimination of conspicuous nurse hertz resonant cavity: $f=\frac{1}{2\mathrm{\π}}\sqrt{\frac{1}{M_A{C}_c}}---\left(4\right)$

Single conspicuous nurse hertz resonant cavity can be regarded a single-degree-of-freedom undamped-free vibration system as, and analogy is with the air quality M in the connecting tube _ARegard mass block m as, can draw cavity (spring) rigidity:

$k=\frac{1}{C_c}=\frac{C^2}{V}---\left(5\right)$

For expressing conveniently, adopt following symbol

$a=\frac{k_1+k_2}{m_1}---\left(6\right)$

$b=\frac{k_2}{m_1}---\left(7\right)$

$d=\frac{k_2}{m_2}---\left(8\right)$

So by quality m ₁, m ₂Spring k ₁, k ₂Form in the two degrees of freedom free oscillating system angular frequency formula:

${{\mathrm{\ω}}^2}_{\mathrm{1,2}}=\frac{1}{2}(a+d)\mathrm{\μ}\frac{1}{2}\sqrt{{(a-d)}^2+4\mathrm{bd}}\left[2\right]---\left(9\right)$

Regard bifrequency air inlet resonant cavity as a binary free oscillating system, then

The gaseous mass of connecting tube A $M_{A_1}=m_1=\frac{l_{c_1}}{S_{c_1}}---\left(10\right)$

The spring rate of cavity A $k_1=\frac{C^2}{V_1}---\left(11\right)$

The gaseous mass of connecting tube B $M_{A_2}=m_2=\frac{l_{c_2}}{S_{c_2}}---\left(12\right)$

The spring rate of cavity B $k_2=\frac{C^2}{V_2}---\left(13\right)$

With formula 10,12,13 substitution formula 6, can obtain

$a=\frac{k_1+k_2}{M_{A_1}}=\frac{c^2{s}_{c_1}(v_1+v_2)}{l_{c_1}{v}_1{v}_2}---\left(14\right)$

With formula 10,13 substitution formula 7, can obtain

$b=\frac{k_2}{M_{A_1}}=\frac{c^2{s}_{c_1}}{l_{c_1}{v}_2}---\left(15\right)$

With formula 12,13 substitution formula 8, can obtain

$d=\frac{k_2}{M_{A_2}}=\frac{c^2{s}_{c_2}}{l_{c_2}{v}_2}---\left(16\right)$

At last with formula 14,15,16 substitution formula 9, can obtain angular frequency square:

${{\mathrm{\ω}}^2}_{\mathrm{1,2}}=\frac{1}{2}(\frac{c^2{s}_{c_1}(v_1+v_2)}{l_{c_1}{v}_1{v}_2}+\frac{c^2{s}_{c_2}}{l_{c_2}{v}_2})\mathrm{\μ}\frac{1}{2}\sqrt{{(\frac{c^2{s}_{c_1}(v_1+v_2)}{l_{c_1}{v}_1{v}_2}-\frac{c^2{s}_{c_2}}{l_{c_2}{v}_2})}^2+\frac{4c^4{s}_{c1}{s}_{c_2}}{l_{c_1}{l}_{c_2}{v_2}^2}}---\left(17\right)$

Because $f_{\mathrm{1,2}}=\frac{{\mathrm{\ω}}_{\mathrm{1,2}}}{2\mathrm{\π}}---\left(18\right)$

The substitution following formula, two that can draw bifrequency air inlet resonant cavity act on frequencies:

$f_1=\frac{\sqrt{(\frac{c^2{s}_{c_1}(v_1+v_2)}{l_{c_1}{v}_1{v}_2}+\frac{c^2{s}_{c_2}}{l_{c_2}{v}_2})+{(\frac{c^2{s}_{c_1}(v_1+v_2)}{l_{c_1}{v}_1{v}_2}-\frac{c^2{s}_{c_2}}{l_{c_2}{v}_2})}^2+4\frac{c^4{s}_{c1}{s}_{c_2}}{l_{c_1}{l}_{c_2}{v_2}^2}}}{2\mathrm{\π}\sqrt{2}}---\left(19\right)$

$f_2=\frac{\sqrt{(\frac{c^2{s}_{c_1}(v_1+v_2)}{l_{c_1}{v}_1{v}_2}+\frac{c^2{s}_{c_2}}{l_{c_2}{v}_2})+{(\frac{c^2{s}_{c_1}(v_1+v_2)}{l_{c_1}{v}_1{v}_2}-\frac{c^2{s}_{c_2}}{l_{c_2}{v}_2})}^2+4\frac{c^4{s}_{c1}{s}_{c_2}}{l_{c_1}{l}_{c_2}{v_2}^2}}}{2\mathrm{\π}\sqrt{2}}---\left(20\right)$

In order to verify the effect of this device; The claimant makes exemplar and has adopted the acoustic equipment of B&K company and software to carry out pipeline transmission loss test; On behalf of single air inlet resonant cavity and bifrequency air inlet resonant cavity, Fig. 3 red curve and blue curve be connected air inlet noise transfer loss situation of change on the admission line respectively; Can find out; Red curve only peak value occurs at 67Hz, and obvious peak value has all appearred in blue curve about 41Hz and 108Hz, explains that this installs the induction noise that can eliminate two different frequencies really effectively.

This device can be realized producing in batches through molding and forming.

Claims (1)

1. automotive engine air intake system bifrequency air inlet resonant cavity; It is characterized in that: it is made up of resonant cavity A resonant cavity B series connection; Resonant cavity A is made up of connecting tube A and cavity A, and resonant cavity B is made up of connecting tube B and cavity B, and cavity A links to each other with admission line through connecting tube A; Link to each other with cavity B through connecting tube B, the connecting tube A length of establishing resonant cavity A is l ₁, the sectional area of connecting tube A does The volume of cavity A is V ₁, the connecting tube B length of resonant cavity B is l ₂, connecting tube B sectional area does The volume of cavity B is V ₂, the formula of two effect frequencies of bifrequency air inlet resonant cavity is following:

$f_1=\frac{\sqrt{(\frac{c^2{s}_{c_1}(v_1+v_2)}{l_{c_1}{v}_1{v}_2}+\frac{c^2{s}_{c_2}}{l_{c_2}{v}_2})+{(\frac{c^2{s}_{c_1}(v_1+v_2)}{l_{c_1}{v}_1{v}_2}-\frac{c^2{s}_{c_2}}{l_{c_2}{v}_2})}^2+4\frac{c^4{s}_{c1}{s}_{c_2}}{l_{c_1}{l}_{c_2}{v_2}^2}}}{2\mathrm{\π}\sqrt{2}}$

$f_2=\frac{\sqrt{(\frac{c^2{s}_{c_1}(v_1+v_2)}{l_{c_1}{v}_1{v}_2}+\frac{c^2{s}_{c_2}}{l_{c_2}{v}_2})+{(\frac{c^2{s}_{c_1}(v_1+v_2)}{l_{c_1}{v}_1{v}_2}-\frac{c^2{s}_{c_2}}{l_{c_2}{v}_2})}^2+4\frac{c^4{s}_{c1}{s}_{c_2}}{l_{c_1}{l}_{c_2}{v_2}^2}}}{2\mathrm{\π}\sqrt{2}}$

C represents the velocity of sound, is 344m/s under the normal temperature.

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