JP2005214049A - Noise release reducing method for intake noise eliminator for supercharger and its device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To further suppress the release of the rotating noises of an impeller in a supercharger to the outside. <P>SOLUTION: At a central portion of a casing 16 formed into a cylindrical shape with one end closed and having an air inlet 18 provided in an outer peripheral wall 16b and an air outlet 17 in the center of an other end wall 16a, a cylindrical noise eliminator cavity 22 is provided which extends to the direction of the axial center and is communicated with the air outlet 17. On the outer peripheral side of the noise eliminator cavity 22, an air intake flow path 23 having a side wall face covered with a sound absorbing material 24 is provided for communicating an outer peripheral portion of the noise eliminator cavity 22 with the air inlet 18. A communication part 25 is provided at the central portion of an one end wall 16c of the casing corresponding to the noise eliminator cavity 22 and an additional space forming member 27 is mounted on the outside thereof to form an additional space 26. The rotating noises of the impeller 7 of a compressor 3 entering from the air outlet 17 into the casing 16 is previously reduced before entering into the air intake flow path 23 by the interaction of a sound field via the communication part 25 between the noise eliminator cavity 22 and the additional space 26. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention is attached to the air intake side of a turbocharger such as an exhaust turbine supercharger, and further reduces noise emission in a silencer for a supercharger that suppresses rotational noise of a compressor impeller that is discharged to the outside. The present invention relates to a method and an apparatus for reducing noise emission of a silencer for a supercharger used in the above.

  As one of exhaust turbine superchargers for diesel engines and gasoline engines, radial turbochargers are widely used. Such a radial turbocharger has a turbine casing 2 of the turbine 1 and a blower casing 4 of the compressor 3 integrated with each other via a bearing casing 5 as shown in FIG. An internal turbine impeller 6 and a blower fan (hereinafter referred to as an impeller) 7 in the blower casing 4 are integrally connected by a turbine shaft 8 rotatably supported in the bearing casing 5. Thereby, the turbine impeller 6 is rotated by the exhaust gas 10 of the engine taken in from the gas inflow passage 9 provided in the outer peripheral portion of the turbine casing 2, the impeller 7 is rotated via the turbine shaft 8, In the blower casing 4, the air 12 taken in from the suction port 11 provided on the tip end side in the axial direction of the impeller 7 is compressed by the rotation of the impeller 7, and the compressed air is provided in the outer peripheral portion of the blower casing 4. It can be sent from the passage 13 to required equipment on the downstream side such as the intake side of the engine. The exhaust gas 10 after being used for rotational driving of the turbine impeller 6 in the turbine casing 2 is exhausted from a gas outlet 14 provided on the front end side in the axial direction of the turbine impeller 6 in the turbine casing 2. is there. Further, the suction port 11 of the compressor 3 is in communication with the outside in order to take in the air 12. For this reason, normally, a suction silencer 15 is attached upstream of the suction port 11 so as to suppress the noise emission to the outside due to the rotational noise of the impeller 7 of the compressor 3.

  This type of suction silencer 15 for a supercharger is configured as follows. That is, an air outlet 17 is provided at the center of the other end wall 16a on the other end side in the axial direction of the cylindrical casing 16 composed of the outer peripheral wall 16b, the one end wall 16c, and the other end wall 16a. Is connected to the suction port 11 of the compressor 3. On the other hand, the outer peripheral wall 16b of the casing 16 is formed with, for example, an air inlet 18 through which air can flow in and out by forming the outer peripheral wall 16b with a punching metal or the like. A cylindrical air suction filter 19 is held. Furthermore, the inside of the casing 16 has an outer diameter such that the outer peripheral surface is in contact with the inner surface of the outer peripheral wall 16b of the casing 16, and an opening having an inner diameter corresponding to the air outlet 17 of the casing 16 at the center. The partition member 20 configured to form the portion 21 is disposed in the casing 16 at a required interval in the axial direction, and each outer peripheral surface is attached to the inner surface of the outer peripheral wall 16b of the casing 16. The opening 21 forms a cylindrical silencer cavity 22 whose one end is closed by one end wall 16 c of the casing 16 and whose other end communicates with the air outlet 17. Between the partition members 20, a radial air suction passage 23 is formed in multiple layers to communicate the muffler inner cavity 22 and the air inlet 18 provided in the casing outer peripheral wall 16 b portion. Air entering from each air inlet 18 of the wall 16 b is guided to the silencer cavity 22 through each air suction passage 23, and is further guided to the air outlet 17 from the silencer cavity 22. It is. Furthermore, the sound absorbing material 24 is adhered to both sides of each partition member 20 so as to provide sound absorbing properties on the side wall surface of each air suction channel 23 (see, for example, Patent Document 1). ). Thus, the external air 12 passes through the air suction filter 19, the air inlet 18, each air suction passage 23, the silencer cavity 22, and the air outlet 17 in the supercharger suction silencer 15 in this order, and then the compressor 3, the rotation noise of the impeller 7 discharged from the suction port 11 of the compressor 3 is transmitted to the air outlet 17 of the suction silencer 15 and the silencer cavity 22. Then, when it is transmitted to the air inlet 18 side through each air suction channel 23, it is absorbed by the sound absorbing material 24 provided on the side wall surface of each air suction channel 23, and the suction silencer The rotational noise level of the impeller 7 of the compressor 3 discharged from the 15 air inlets 18 to the outside can be reduced.

  The partition members 20 housed in the casing 16 of the suction silencer 15 are maintained at a required interval. As a means for this, the outer peripheral end is the axial direction on the inner surface of the casing outer peripheral wall 16b. It can be attached to a required interval position, a spacer-like member (not shown) can be interposed, or can be attached to a required interval position of a connecting member extending in the axial direction in the casing 16.

Japanese Utility Model Publication No. 53-46410

  However, according to the conventional suction silencer 15 for the supercharger, the rotational noise of the impeller 7 of the compressor 3 released to the outside can be reduced. However, in recent years, the compressor 3 in the exhaust turbine supercharger tends to have a higher efficiency and a larger flow rate, and accordingly, the rotational noise of the impeller 7 also tends to increase. However, the reality is that it is desired to be able to suppress further.

  In view of this, the present inventor has devised and researched the above-described conventional turbocharger as a result of repeated suppression of noise emission to the outside of the rotation noise of the impeller of the compressor in the supercharger suction silencer. In the suction silencer for compressors, paying attention to the fact that the noise is not reduced until the rotation noise of the compressor impeller enters the suction silencer after entering the suction silencer, the rotation of the impeller If noise reduction measures are taken before the noise enters the air suction flow path in the supercharger suction silencer, as a result, after passing through the air suction flow path, the noise is discharged to the outside from the air inlet. It was found that the noise emission of the impeller rotation noise can be further reduced, and the present invention has been made.

  Accordingly, an object of the present invention is to provide a suction silencer for a supercharger that can further reduce noise emission of impeller rotation noise in the supercharger that is discharged to the outside through the suction silencer for the supercharger. It is an object of the present invention to provide a method and an apparatus for reducing noise emission from a vessel.

  In order to solve the above problems, the present invention forms a large number of air inlets on the outer peripheral wall to close one end side in the axial direction, and an air outlet provided in the central part on the other end side serves as a suction port of the compressor. In the cylindrical casing that can be connected, an air suction passage for guiding the air entering from the air inlet from the outer peripheral portion of the casing toward the axial center portion of the casing is formed in multiple layers, and the shaft of the casing A silencer internal cavity is provided to guide the air guided to the core to the air outlet, and external air passes through the air inlet, the air suction flow path, the silencer internal cavity, and the air outlet to the downstream side. At the same time that the compressor impeller is discharged from the compressor suction port and travels backward through the air flow path, the compressor impeller rotational noise passes through the air suction flow paths and passes through the air suction flow paths. of In the suction silencer for a supercharger that is designed to absorb noise by a sound material and to suppress noise emission, it is partitioned by a partition wall provided with a communication portion at an end on the side opposite to the air outlet of the cavity in the silencer. Characterized in that noise is reduced in advance before entering the air suction flow path from inside the silencer cavity by the interaction of the sound field between the additional space and the cavity inside the silencer. A noise reduction method for a suction silencer for a supercharger, a plurality of air inlets formed on the outer peripheral wall to close one end in the axial direction, and an air outlet provided at the central portion on the other end to the compressor In the cylindrical casing that can be connected to the suction port of the air inlet, the air suction channel that guides the air entering from the air inlet toward the axial center of the casing from the outer periphery of the casing is formed in multiple layers, The air led to the axial center of the casing A silencer internal cavity that guides to the air outlet is provided, and external air is sucked into the compressor on the downstream side through the air inlet, the air suction flow path, the silencer internal cavity, and the air outlet, and at the same time, the compressor When the compressor impeller rotational noise that is discharged from the suction port and travels backward through the air flow path passes through the air suction passages, the noise is absorbed by the sound absorbing material in the air suction passages. In the suction silencer for a supercharger configured to suppress noise emission, an additional space partitioned by a partition wall provided with a communication portion is provided at an end on the side opposite to the air outlet of the cavity in the silencer. It is set as the discharge noise reduction apparatus of the suction silencer for superchargers which has a structure.

  Moreover, it is set as the structure provided with the some communication part in the partition wall which partitions off the cavity in a silencer and additional space in the said structure.

According to the present invention, the following excellent effects are exhibited.
(1) A cylindrical casing in which a large number of air inlets are formed in the outer peripheral wall to close one end in the axial direction, and an air outlet provided at the center of the other end can be connected to the compressor inlet The air suction flow path for guiding the air entering from the air inlet from the outer peripheral portion of the casing toward the axial center portion of the casing is formed in multiple layers, and the air guided to the axial center portion of the casing is A silencer internal cavity is provided to guide the air to the air outlet, and external air is sucked into the compressor on the downstream side through the air inlet, the air suction passage, the silencer internal cavity, and the air outlet, and at the same time, When the compressor impeller rotational noise that is released from the suction port and travels backward in the air flow path passes through the air suction passages, the noise is absorbed by the sound absorbing material in the air suction passages. Release In the suction silencer for a supercharger that can be controlled, an additional space partitioned by a partition wall having a communication portion is provided at an end on the side opposite to the air outlet of the cavity in the silencer. And the noise of the supercharger suction silencer, wherein the noise is reduced in advance before entering the air suction flow path from the inside of the silencer cavity by the interaction of the sound field with the cavity in the silencer Release reduction method, and a cylinder in which a large number of air inlets are formed on the outer peripheral wall to close one end in the axial direction, and an air outlet provided in the central portion on the other end can be connected to the suction port of the compressor In the casing of the mold, an air suction passage for guiding the air entering from the air inlet from the outer peripheral portion of the casing toward the axial center portion of the casing is formed in multiple layers and led to the axial center portion of the casing. Turn off the air to guide the air to the air outlet. An external cavity is provided, and external air is sucked into the compressor on the downstream side through the air inlet, the air suction flow path, the silencer internal cavity, and the air outlet, and at the same time, the air is discharged from the suction port of the compressor. When the rotation noise of the impeller of the compressor traveling in the reverse flow path passes through each of the air suction passages, the noise is absorbed by the sound absorbing material in each of the air suction passages so that noise emission can be suppressed. In the supercharger suction silencer, the supercharger suction silencer has a configuration in which an additional space partitioned by a partition wall provided with a communication portion is provided at an end on the side opposite to the air outlet of the cavity in the silencer. Therefore, it is possible to cause an interaction between the sound field of the silencer cavity communicated via the communication part and the additional space, and this interaction results in the above silencer. Advance from the air outlet to the inner cavity Rotational noise of the compressor impeller that enters can be reduced before entering the air suction passage. Therefore, since the noise entering the air suction passage can be reduced in advance from the outer peripheral portion of the silencer inner cavity, the rotation of the impeller in the supercharger released to the outside through the air suction passage and the air inlet The noise emission of noise can be further reduced.
(2) By adopting a configuration in which a plurality of communicating portions are provided in the partition wall that partitions the cavity in the silencer and the additional space, the interaction of the sound fields of both the cavity in the silencer and the additional space can be promoted. This makes it possible to reduce noise in many acoustic mode bands.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 shows an embodiment of a noise emission reduction method and apparatus for a supercharger suction silencer according to the present invention. In the same configuration as the supercharger suction silencer 15 shown in FIG. An additional space 26 is provided on one end side of the internal cavity 22 with a partition wall having a plurality of communication portions (communication ports) 25 interposed therebetween, and is added to the silencer internal cavity 22 partitioned by the partition wall. Both sound fields in the space 26 are caused to interact, thereby reducing the noise in the silencer cavity 22 where the rotational noise of the impeller 7 of the compressor 3 enters directly through the air outlet 17, and the air suction flow path The noise entering 23 is reduced in advance.

  More specifically, an additional space forming member having a cylindrical shape of a required length having an inner diameter corresponding to the silencer cavity 22 outside the central portion of the one end wall 16c of the casing 16 and having one end side closed. 27, and the other end of the additional space forming member 27 is airtightly attached to the outer surface of the one end wall 16c of the casing 16, and the additional space 26 having a required volume is formed inside the additional space forming member 27. Let it form. Further, a plurality of communication portions 25 are provided at a required position of the central portion of the one end wall 16 c of the casing 16 so as to communicate with the additional space 26. Thereby, the central part of the casing one end wall 16c provided with the plurality of communication portions 25 is caused to function as a partition wall between the muffler inner cavity 22 and the additional space 26.

  Other configurations are the same as those shown in FIG. 7, and the same components are denoted by the same reference numerals.

  Next, calculation results predicted using the finite element analysis method for the noise reduction effect of the noise reduction method and apparatus of the supercharger suction silencer of the present invention having the above-described configuration will be described.

Here, previously, the boundary surface S ₁ to the normal direction component u _n of the medium displacement is designated, the sound field is surrounded by a boundary surface S ₂ that the impedance Z is specified for a finite element analysis described Then, the correction method when the additional space is installed by dividing the sound field finite element analysis method by a wall having a communication portion will be described.

ここで、ρ：媒質（空気）の密度（１．２ｋｇ／ｍ^３） That is, first, when the energy principle that is the basis of the finite element analysis is derived, the kinetic energy T and the potential energy U are expressed as follows using the sound pressure p and the medium displacement u, respectively.

Here, ρ: density of medium (air) (1.2 kg / m ³ )

ここで、ｊ：虚数単位（√（−１））、ω：角振動数
を上記（１）式に代入することにより、以下のように音圧ｐで表される。

The kinetic energy T is the equation of motion

Here, by substituting j: imaginary unit (√ (−1)) and ω: angular frequency into the above equation (1), it is expressed as sound pressure p as follows.

と

を上記（１）式に代入することにより、以下のように音圧ｐのみで表される。

On the other hand, the potential energy U is a relationship in which the divergence (volume change) of the displacement of the medium is expressed by the bulk modulus K.

When

By substituting into the above equation (1), it is expressed only by the sound pressure p as follows.

Further, the work W to be done at the boundary surface, the boundary surface is divided into a surface S ₂ of the surface S ₁ and the impedance Z normal component u _n of the medium displacement is designated is designated can be expressed as follows .

となる。 From the above, Lagrange Juan L

It becomes.

ここで、

によって表し、要素内音圧が４節点で節点音圧ベクトルに等しい条件より未定係数ベクトルａを節点音圧ベクトルで

と表す。上記式（１１）を式（９）に代入すると、

となる。上記式（１２）を式（８）に代入してラグランジュアンＬを節点音圧で表す。たとえば、第１項は、

のように節点音圧で表すことができる。なお、上記におけるＺ_１ｅは、

としてある。 Next, a method of discretizing the above equation (8) with cylindrical coordinates and converting it into a matrix equation will be outlined. For one element as shown in FIG.

here,

The undetermined coefficient vector a is expressed as a nodal sound pressure vector under the condition that the sound pressure within the element is equal to the nodal sound pressure vector at 4 nodes

It expresses. Substituting the above equation (11) into equation (9),

It becomes. The above formula (12) is substituted into the formula (8), and the Lagrangian L is expressed by the nodal sound pressure. For example, the first term is

It can be expressed by the nodal sound pressure. In addition, Z _1e in the above is

It is as.

  As a result, an algebraic equation related to the nodal sound pressure is derived from the stationary condition related to the variation of the nodal sound pressure in Lagrangian.

ここで、ｕ_ｃ：連通部内の空気の変位（連通部２５は短いため、その中の空気は一体として運動すると考えてよい。）、Ｓ_ｃ：連通部２５の断面積、ｈ_ｃ：連通部２５の長さ（仕切壁となるケーシング一端壁１６ｃの厚さ）、Ｃ：減衰定数、Δｐ_ｃ：連通部２５における騒音抑制対象空間となる消音器内空洞２２側の出口での音圧から、付加空間２６側の出口での音圧を引いた音圧差 Next, a correction method when the sound field finite element analysis method is applied to a case where an additional space is installed by partitioning with a wall having a communication portion will be described. As shown in FIG. 3, a required additional space 26 is provided on one end side of the silencer cavity 22 as a noise suppression target space with a casing end wall 16 c as a partition wall provided with a plurality of communication portions 25 interposed. First, assuming that there is no communication portion 25, the above-described sound field finite element analysis is separately performed on the silencer cavity 22 and the additional space 26, and an algebraic equation regarding the nodal sound pressure is obtained. Lead. Next, assuming that the communication part 25 exists, the displacement of the air in each communication part 25 is added as a new degree of freedom, and the equation of motion of the air in the communication part 25 is derived as follows.

Here, u _c : displacement of air in the communication part (the communication part 25 is short, so the air in it may be considered to move as a unit), S _c : cross-sectional area of the communication part 25, h _c : communication part the length of 25 (the thickness of the casing end wall 16c of the partition wall), C: from the sound pressure at the outlet of the muffler cavity 22 side to be noise suppression target space in the communicating portion _25,: attenuation constant, Delta] p c Sound pressure difference minus the sound pressure at the exit on the additional space 26 side

Further, it is necessary to add a portion corresponding to the S ₁ integral term of the equation (8) to the equation system related to the silencer cavity 22 and the additional space 26 derived by the displacement of the air in each communication portion 25.
At this time, pay attention to the following points. That is, the displacement u _c of the air in each communication unit 25, since the direction towards the additional space 25 from the muffler cavity 22 are a positive direction, u _n of S ₁ the integral term in equation (8), mute Note that u _c must be taken into account for the internal cavity 22 and −u _c for the additional space 26. The entire system including the silencer cavity 22 and the additional space 26 derived as described above is solved, and the sound field in the case where the communication portion 25 and the additional space 26 are provided is obtained. .

  An evaluation model of the supercharger suction silencer 15 provided with the noise emission reducing device of the present invention is set as shown in FIG. A square shown by a solid line in FIG. 4 is a cylindrical silencer inner cavity 22 formed at the center of the supercharger suction silencer 15 and one end of the silencer inner cavity 22 on the side opposite to the air outlet 17. The cross section corresponding to the radius portion of the additional space 26 formed by attaching the additional space forming member 27 to the outer side of the casing one end wall 16c as a partition wall provided with a plurality of communication portions 25 on the side (right side in the figure) Is shown with the central axis of the silencer inner cavity 22 and the additional space 26 as the lower side. The silencer inner cavity 22 has a radial dimension (r direction) of 0.5 m, and the noise inlet side. The connection side end portion with the compressor 3, that is, the air outlet 17 side end portion is set as the sound source side end portion (z = 0), and the length is 0.8 m in the axial direction (z direction). It is. Therefore, the upper side of the square indicated by the solid line in FIG. 4 indicates the outer peripheral portion of the silencer cavity 22 that becomes the connection portion with the air suction flow path 23 (indicated by a one-dot chain line in FIG. 4).

  In addition, each of the communication portions 25 is 0.01 m in the r direction at equal intervals in the r direction (radial direction) where r = 0.05, 0.10, 0.15,. It is set to be formed in a slit shape having a width (in FIG. 4, for convenience, the width of each communication portion 25 is wide and the number is omitted). In addition, when trying to actually form each communication part 25 as the above arrangement, each communication part 25 is arranged axially symmetric with respect to the z-axis, that is, concentrically. In this case, For example, each communication portion 25 may be divided at a required interval in the circumferential direction so that a wall portion continuous in the radial direction is left on the casing one end wall 16c.

  Under the above settings, the above-described finite element analysis method is used to analyze the cylindrical region in the silencer cavity 22 and the additional space 26. As the noise source, the air outlet 17 side end portion (z = 0, that is, the left side of the square shown by the solid line in FIG. 4) in the silencer inner cavity 22 is vibrated with a sound pressure of 1. As a noise index, the sum of the sound pressure gains at the nodes in the outer peripheral portion of the silencer cavity 22 that becomes the connection portion with the air suction flow path 23 is obtained as a function of the excitation frequency. The number of element divisions was 10 in the r direction, 16 in the silencer cavity 22 in the z direction, and 1 in the additional space 26. The reason why the number of divisions in the z direction with respect to the additional space 26 is small is that the additional space 26 is set to be small so that space can be saved, and the noise reduction effect can be obtained even with such a small additional space 26. This is apparent from the results of finite element analysis shown in FIGS. 5 and 6 to be described later.

Note that the greater the admittance is the reciprocal of the impedance (complex number), the higher the sound absorption, and the smaller the admittance, the closer to a rigid body surface without sound absorption. Therefore, in the above evaluation model, the admittance of the connection portion with the air suction flow path 23 in the outer peripheral portion of the silencer inner cavity 22 is in contact with the air on the air suction flow path 23 side, and therefore 0.004 + j0.002 [m ³ / Ns] (j is an imaginary unit, the same applies hereinafter) and is set to a relatively large value as close to sound absorption. On the other hand, both surfaces of the one end wall 16c of the casing 16 and the inner surface of the additional space forming member 27 are both close to a rigid surface, and the admittance is set as 0.0001 + j0.0001 [m ³ / Ns]. is there.

  The solid line shown in FIG. 5 is a case where the length dimension in the z direction of the additional space 26 is 0.04 m, and the thickness dimension of the casing one end wall 16c as a partition wall corresponding to the length dimension of the communication portion 25 is 0.008 m. 2 shows the frequency characteristics of the sum of the sound pressure gains at the nodes in the outer peripheral portion of the silencer cavity 22 obtained.

  The solid line shown in FIG. 6 indicates that the additional space 26 has a length in the z direction of 0.05 m, and the thickness of the casing one end wall 16c as a partition wall corresponding to the length of the communication portion 25 is 0.010 m. The frequency characteristic of the sum of the sound pressure gains at the nodes in the outer peripheral portion of the silencer cavity 22 obtained in this case is shown.

  Note that the broken lines shown in FIGS. 5 and 6 show the results when the additional space 23 is eliminated and the communication portion 25 is closed as a comparison.

  From these results, by comparing the solid line and the broken line in FIG. 5 and comparing the solid line and the broken line in FIG. 6, a partition wall having a plurality of communication portions 25 on one end side of the cavity 22 in the silencer is obtained. When the additional space 26 partitioned is provided, the silencer 22 enters the silencer cavity 22 from the air outlet 17 as compared with a case where one end of the silencer cavity 22 is a rigid closed surface. It can be seen that noise is reduced at the outer periphery of the internal cavity 22.

  In any of the cases described above, it can be seen that the resonance peaks that occur in many acoustic mode bands when the additional space 26 is not provided are reduced.

  Therefore, according to the suction silencer for a supercharger of the present invention, the noise reduction is compared with the case where one end of the silencer internal cavity 22 is closed by the one end wall 16c of the casing 16 as shown in FIG. Noise in the outer peripheral portion of the internal cavity 22 can be reduced, and a noise reduction effect can be produced before entering the air suction passage 23. As a result, by applying the noise emission reduction method and apparatus of the present invention to the supercharger suction silencer 15 attached to the upstream side of the suction port 11 in the compressor 3 of the exhaust turbine supercharger, the silencer of the suction silencer 15 is applied. It is possible to further reduce the rotational noise of the impeller 7 of the compressor 3 that is discharged to the outside through the air suction passage 23 and the air inlet 18 after passing through the internal cavity 22. In addition, since a plurality of communication portions 25 are provided and the interaction between the sound fields of the silencer cavity 22 and the additional space 26 can be promoted, the noise in the silencer cavity 22 can be reduced. Resonance peaks occurring in the acoustic mode band can be reduced. For this reason, it becomes possible to reduce annoying noise efficiently.

  The present invention is not limited only to the above-described embodiment, and the size, shape, number, and arrangement of the communication portion 25 can be adjusted as long as the silencer cavity 22 and the additional space 26 can communicate with each other. You may change suitably according to the size etc. of the cavity 22 inside a container. The size of the additional space 26 may be appropriately increased or decreased depending on the size of the supercharger suction silencer 15 to be applied or the size of the cavity 22 in the silencer. There is a silencer inner cavity 22 that extends in the axial direction at the center of the casing 16 and communicates with the air outlet 17, and the air provided on the outer circumference of the silencer inner cavity 22 and the casing outer peripheral wall 16 b on the outer periphery thereof. In the case of the supercharger suction silencer 15 having an air suction passage 23 communicating with the inlet 18, the supercharger suction silencer 15 having a different diameter of the casing 16 and the diameter of the silencer cavity 22 is used. It can also be applied to a supercharger suction silencer 15 in which the shape (path) of the air suction passage 23 is bent. Of course, various changes can be made without departing from the scope of the present invention.

It is a schematic sectional drawing which shows one Embodiment of the noise emission reduction method and apparatus of the suction silencer for superchargers of this invention. It is a figure which shows the element for the finite element analysis used in order to verify the noise reduction effect in the apparatus of FIG. It is a schematic diagram for demonstrating the method of the finite element analysis used in order to verify the noise reduction effect in the apparatus of FIG. It is a figure which shows the evaluation model used in order to verify the noise reduction effect in the apparatus of FIG. In the evaluation model of FIG. 4, the sound at the node in the outer peripheral portion of the cavity in the silencer obtained when the length dimension of the additional space in the z direction is 0.04 m and the thickness dimension of the casing one end wall is 0.008 m. It is a figure which shows the frequency characteristic of the sum of a pressure gain. In the evaluation model of FIG. 4, the sound at the node in the outer peripheral portion of the cavity in the silencer obtained when the length dimension of the additional space in the z direction is 0.05 m and the thickness dimension of the casing one end wall is 0.010 m. It shows the frequency characteristics of the sum of pressure gains. It is sectional drawing which shows the outline of an example of an exhaust turbine supercharger.

Explanation of symbols

3 Compressor 7 Impeller 11 Suction Port 12 Air 15 Supercharger Suction Silencer 16 Casing 16a Other End Wall 16b Outer Wall 16c One End Wall (Partition Wall)
17 Air outlet 18 Air inlet 22 Silencer cavity 23 Air suction flow path 24 Sound absorbing material 25 Communication portion 26 Additional space

Claims (3)

  In a cylindrical casing in which a large number of air inlets are formed in the outer peripheral wall to close one end side in the axial center direction, and an air outlet provided in the central part on the other end side can be connected to the suction port of the compressor. An air suction passage is formed in multiple layers to guide the air entering from the air inlet toward the axial center of the casing from the outer periphery of the casing, and the air guided to the axial center of the casing is supplied to the air outlet. A silencer internal cavity is provided to guide the outside air through the air inlet, the air suction flow path, the silencer internal cavity, and the air outlet to the compressor on the downstream side. When compressor impeller rotation noise that is released and travels backward through the air flow path passes through each air suction flow path, it is absorbed by the sound absorbing material in each air suction flow path to suppress noise emission. so In the supercharger suction silencer configured as described above, an additional space partitioned by a partition wall provided with a communication portion is provided at an end on the side opposite to the air outlet of the cavity in the silencer. Noise emission of a suction silencer for a supercharger characterized in that noise is reduced in advance before entering the air suction flow path from the inside of the silencer cavity by the interaction of the sound field with the cavity in the silencer Reduction method.   In a cylindrical casing in which a large number of air inlets are formed in the outer peripheral wall to close one end side in the axial center direction, and an air outlet provided in the central part on the other end side can be connected to the suction port of the compressor. An air suction passage is formed in multiple layers to guide the air entering from the air inlet toward the axial center of the casing from the outer periphery of the casing, and the air guided to the axial center of the casing is supplied to the air outlet. A silencer internal cavity is provided to guide the outside air through the air inlet, the air suction flow path, the silencer internal cavity, and the air outlet to the compressor on the downstream side. When compressor impeller rotation noise that is released and travels backward through the air flow path passes through each air suction flow path, it is absorbed by the sound absorbing material in each air suction flow path to suppress noise emission. so The supercharger suction silencer configured as described above has a configuration in which an additional space partitioned by a partition wall provided with a communication portion is provided at the end on the side opposite to the air outlet of the cavity in the silencer. A noise reduction device for a suction silencer for a supercharger.   3. The noise reduction device for a supercharger suction silencer according to claim 2, wherein a plurality of communicating portions are provided in a partition wall that divides the cavity inside the silencer from the additional space.

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