JP2002004964A - Silencer of supercharger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To compact the silencer, to provide a sufficient silencing effect, to reduce pressure loss, and to improve efficiency of the supercharger. SOLUTION: Sound absorbing cylinders 1 having longitudinal central parts which are recessed and bent toward the center of a silencer casing 3 are arranged concentrically in the silencer casing 3, depth corresponding to the axial direction of the sound absorbing cylinders 1 can be short, and high performance silencing can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silencer for a turbocharger, which silences noise at a suction port of the turbocharger and improves fuel efficiency of the engine to contribute to fuel saving. The present invention relates to a silencer suitable for being applied to a supercharger for a vehicle.

[0002]

2. Description of the Related Art Generally, large diesel engines are
Superchargers have been used to enhance their performance.However, in recent years, turbochargers have been required to have a high pressure ratio and high efficiency in order to increase the output of diesel engines. It is to be driven at a rotational speed. And the noise level from the supercharger is also increased by driving the supercharger at a high rotational speed.

[0003] Noise from the supercharger is divided into noise upstream of the compressor and noise radiated from the surface of the air passage on the engine side. , The air flow at the compressor inlet affects the noise level.

[0004] By the way, looking at the noise of the supercharger,
As shown in FIG. 9, the supercharger has a fundamental frequency represented by the number of rotations × the number of blades having a high frequency (for example, 9000 rpm × 1).
1 (22) sheets / 60 (sec) = 1650 (3300) H
z), and the noise in the vicinity of the fundamental frequency and its overtone component is at a higher level than the other frequencies.

The noise generated at the suction port of the turbocharger differs depending on the suction air volume and the discharge pressure.
The level is 0 to 150 dB (A). Since the noise generated by the engine using the turbocharger is about 100 dB (A), the noise after passing through the suction silencer of the turbocharger must also be reduced to about 100 dB (A). Is required.

The discharge pressure of the supercharger is 3.5 / ■ ²
Although around G, if the pressure loss of the suction silencer attached to the suction port of the supercharger is small, the discharge pressure of the supercharger increases, and the efficiency of the supercharger increases. The efficiency of this turbocharger is 60-70%, and turbocharger manufacturers around the world
Aiming for high efficiency in the 0% range, we are cutting down on the rivals. Generally, it is said that reducing the pressure loss on the suction side by 10 ° Aq improves the efficiency of the turbocharger by 1%. Therefore,
For a suction silencer of a supercharger, reducing the pressure loss is as important as increasing the silencing volume.
In other words, by increasing the efficiency of the supercharger, the fuel efficiency of the engine is improved, which greatly contributes to fuel saving.

In general, typical structures of a suction silencer of a large turbocharger include a cylindrical outer circumference suction type and a square front suction type which are classified according to a flow direction of suction air.

A silencer 7 of a cylindrical outer peripheral suction type shown in FIG.
0, the suction surface of the silencer 70 is on the outer peripheral side of the silencer main body 74 having a cylindrical shape as a whole by connecting a plurality of cylinders 74A, 74a,... As a result, high-temperature air warmed by the engine is sucked in from the suction portion facing the side or directly above the engine, and relatively low-temperature air in the engine room is sucked into the suction portion on the opposite side of the engine. Because of the suction, an imbalance occurs in the suction temperature, and the suction air volume is not constant.

As shown in FIG. 7B, the flow of air is reduced by the outer peripheral surface 73a of the cylindrical portion of the cylindrical outer peripheral suction type silencer 70.
, And merges at the central portion of the cylindrical portion 71 to change the direction of the flow at right angles to the compressor 76 of the supercharger.
To flow into. Therefore, when passing through the silencing element 72 mounted on the silencer main body 74, the flow velocity is increased from the outer peripheral surface 73a to the inner peripheral surface 73b, and the pressure loss increases. That is, the silencer 74
At the center of the air flow, the air flows merge while changing the flow at a right angle while increasing the flow velocity, so that a bending loss causes a large pressure loss. As described above, the cylindrical outer peripheral suction type silencer 74 has a structure in which the pressure loss increases.

When the pressure loss increases as described above, the intake air amount decreases, and the efficiency of the turbocharger decreases, resulting in a decrease in fuel efficiency.

Further, a silencer 70 of a cylindrical outer peripheral suction type.
Is mounted on the engine directly connected to the turbocharger.
Therefore, in order to install the silencer 70, the outer diameter of the cylindrical outer peripheral suction type silencer 70 must be approximately the same as the outer diameter of the supercharger. In addition, the inner diameter is also determined by the inlet diameter (D _T ) of the turbocharger. Therefore, the passage length {(outside diameter D 0 _-inside diameter D _I ) / 2} of the sound passing through the silencing element 72 is limited in shape, and there is a limit in increasing the silencing volume.

On the other hand, a square front suction type silencer 80
As shown in FIG. 8, in particular, as shown in FIG. 8B, the outer shape of the supercharger 81 is circular, while the outer shape of the silencer 80 including the silencing element portion 84 is rectangular, Parts must be secured for placement.
That is, in the narrow engine room, the silencer 80
Must be routed around the four corners, and the arrangement of the silencer 80 is complicated.

In addition, since the suction port of the supercharger 81 is circular, in a square front suction type silencer 80, a flow reducing portion for smoothly changing the shape from a square (square) to a circle is provided downstream of the silencer 80. 85 is provided to reduce the pressure loss. Since the dimension of the contraction portion 85 in the air flow direction is long, the position of the center of gravity of the silencer 83 is far from the surface of the fitting flange 86 of the suction port.

The silencer 80 of the supercharger 81
Is mounted in a cantilever manner on a fitting flange 86 of a suction port of the supercharger 81, and the entire weight of the silencer 80 is supported by the fitting flange 86 of a suction port of the supercharger 81. For this reason, when the position of the center of gravity of the silencer 80 is far from the flange 86, the exciting force at the time of driving becomes large, and the load acting on the fitting flange 86 of the suction port of the turbocharger becomes large. Is required.

Further, a square front suction type silencer 80 is provided.
Has a circular cross section, the flow of air sucked from the front of the silencer 83 contracts to the circular cross section of the coupling flange 86 while accelerating the flow. The depth of the silencer 83 is approximately the same as one side of the outer shape,
Among them, the contraction part occupies 3/4.

Accordingly, the constricted flow of the air flow conically condensed is formed in this constricted portion, and the sound deadening element portion 84 having a depth of 1/4 located upstream is also affected by the condensed air. And the air flow slows down or stagnates at the four corners. When the flow in the central portion of the silencing element 84 increases, the pressure loss increases, which is a major cause of reductions in the intake air volume, the efficiency of the supercharger, and the fuel efficiency.

In view of the foregoing, it is an object of the present invention to provide a silencer for a turbocharger which is compact, can sufficiently exhibit a silencing effect, has a small pressure loss, and can improve the efficiency of the turbocharger. I do.

[0018]

According to a first aspect of the present invention, there is provided a silencer for a turbocharger, wherein a central portion of a silencer casing in an axial direction of a silencer casing is arranged in a central direction. The point is that the sound absorbing cylinders that are curved so as to be annularly concave toward are arranged concentrically. By adopting such a configuration, the depth corresponding to the axial direction of the sound absorbing cylinder can be reduced to a short dimension, and a high-performance silencing volume can be obtained. In other words, sound waves, which are supercharger noises, can be forcibly collided with the sound absorbing surface of the concave portion, so that sound energy can be effectively absorbed by the sound absorbing material, and a large volume reduction can be obtained.

A feature of the silencer of the turbocharger according to the second aspect of the present invention is that the thickness of the sound absorbing cylinder at the axial center is smaller than the thickness near the end. By adopting such a configuration, the flow velocity of the air flowing through the central portion in the axial direction of the sound absorbing cylinder can be made slower than the flow velocity of the air flowing near the end of the sound absorbing cylinder, and the pressure loss due to the curvature of the central portion can be reduced. be able to.

[0020]

1 and 2 show an embodiment of a silencer for a supercharger according to the present invention. Figure 1
A and B show the entire silencer according to the present invention, and a supercharger (not shown) is attached to a portion adjacent to the silencer 10 via a fitting flange 11.

As shown in FIG. 1B, the silencer 10 includes a silencing element section 9 and a contraction section 5. The silencer element 9 is covered with a cylindrical silencer casing 3 at its outer periphery. Inside the silencer casing 3, a plurality of sound absorbing cylinders 1 described later are arranged concentrically. Have been.

The contraction portion 5 connected to the muffling element portion 9 is connected to an end of a circular cross section of the silencer casing 3 from an engagement flange 1 serving as an air suction port of a supercharger.
It is formed by a substantially frustoconical casing that extends converging into one circular opening. 1B is a suction port (not shown) for sucking air, and a suction filter 7 covering the suction port is attached to the silencer casing 3 and stretched. .

Each of the sound absorbing cylinders 1 disposed in the silencer casing 3 has a substantially cylindrical shape, and the sound absorbing cylinders 1 are arranged concentrically around a central axis 3 a of the silencer casing 3. Stored. Specifically, an annular concave portion 1a is formed so that the center of each sound absorbing cylinder 1 in the axial direction of the silencer casing 3 is directed toward the center on the outer peripheral surface of the sound absorbing cylinder 1 and the inner peripheral surface of the sound absorbing cylinder 1 is formed. Forming an annular projection 1b,
Is configured to be curved in the center direction by the annular concave portion 1a and the annular projection 1b.

As shown in FIG. 2, the detailed structure of each of the sound absorbing cylinders 1 is composed of an outer cylinder 12 and an inner cylinder 13 which are connected to each other. The outer cylinder 12 and the outer cylinder 13 are each formed of a perforated plate made of aluminum, and the outer cylinder 12 and the inner cylinder 13 each have a central portion in the axial direction with the annular concave portion 1a and the annular projection. In order to form 1b, the silencer casing 3 has a shape recessed toward the center.

Further, a partition plate 11 is provided between the outer cylinder 12 and the inner cylinder 13, and a sound absorbing material 14 such as class wool is attached to both surfaces of the partition plate 11. The material 14 has a size that matches the shape of the perforated plates forming the outer cylinder 12 and the inner cylinder 13. Further, both ends of the sound absorbing cylinder 1 are closed by a mold member 15, respectively. In the present embodiment, a mountain-shaped extruded aluminum member is used as the mold member 15.

On the inner peripheral surface of the silencer casing 3, the annular concave portion 1 of the sound absorbing cylinder 1 disposed at the outermost periphery is provided.
An annular projection 3b is provided to protrude so as to oppose a. At the center of the silencer casing 3, a column 16 for forming a gap is disposed so as to extend in the axial direction of the silencer casing 3, and the outer peripheral surface of the column 16 is An annular concave portion 16a is provided so as to face the annular projecting portion 1b of the sound absorbing cylinder 1 disposed on the inner periphery. The annular projections 3 of these silencer casings 3
b and the annular concave portion 16a of the cylindrical body 16, a passage similar to the passage 1c between the pair of adjacent sound absorbing tubes 1 and 1 shown in FIG. 2 is formed outside the outermost sound absorbing tube 1 and the innermost sound absorbing tube 1. Will be formed inside.

The flow of sound waves supplied to the supercharger in the silencer of the present embodiment having the above-described configuration will be described.

The sound wave from the direction of the supercharger (not shown in FIG. 1) travels through the contraction section 5 in the direction opposite to the air and enters the silencer casing 3. The sound waves introduced into the silencer casing 3 are formed between a pair of adjacent sound absorbing cylinders 1 and 1, between the outermost sound absorbing cylinder 1 and the silencer casing 3, and between the innermost sound absorbing cylinder 1 and the cylindrical body 16. When the vehicle passes through the parallel passage 1c, it is prevented from going straight by the annular recesses 1a, 16a and the annular protrusions 1b, 3b. And
The sound absorbing surface 1d of each silencer 1 having a curved shape
For this reason, the energy of the sound wave is favorably absorbed by the sound absorbing material 14 in each sound absorbing cylinder 1.

Next, the supercharger noise when the sound absorbing cylinder 1 of this embodiment shown in FIG. 3A and the simple cylindrical sound absorbing cylinder 21 shown in FIG. 3B are arranged concentrically with the same arrangement pitch. Compare the mute state. In FIG. 4, the sound deadening volume of the sound absorbing cylinder 1 of the present embodiment indicated by (（) is about twice the sound deadening volume of the cylindrical sound absorbing tube 21 indicated by (２１) at each frequency. It is evident that the silencing volume of the sound absorbing tube 10 far exceeds the silencing volume of the sound absorbing tube 21.

According to the simple cylindrical sound absorbing cylinder 21 described above, frequencies having wavelengths matching the arrangement pitch can be silenced to some extent, but silencing at other frequencies outside the pitch becomes extremely poor. I have. This is because in the simple cylindrical sound-absorbing cylinder 21, there occurs a phenomenon that frequencies other than the wavelength matching the pitch pass through without being absorbed. Here, assuming that the arrangement pitch of the sound-absorbing cylinder 1 is 100 °, the frequency of the wavelength that matches the arrangement pitch is 340 (m) from frequency = sound speed / wavelength (pitch). / S) /
0.1 (m) = 3400 Hz. This frequency 340
The turbocharger noise at 0 Hz is well absorbed, but as it goes away from this frequency, the sound absorption decreases sharply.

On the other hand, according to the concentric arrangement of the sound absorbing cylinders 1 of the present embodiment, the parallel passages 1c formed between the pair of adjacent sound absorbing cylinders 1 and 1 are connected to the respective sound absorbing cylinders 1 and 2. The sound wave forcibly collides with the sound absorbing surface 1d of each sound absorbing cylinder 1 because it is curved at the central part in the axial direction of the sound absorbing cylinder 1. Thereby, the energy of the sound wave is effectively absorbed by the sound absorbing material 14 in each sound absorbing cylinder 1, so that a large silencing volume can be obtained.

This means that the present invention can be adapted to other frequencies, centering on the frequency (sound speed / wavelength (pitch)) of the wavelength that matches the arrangement pitch (the interval between adjacent sound absorbing cylinders 1 and 1). is there. In particular, a great effect can be exerted on high-frequency waves having strong linearity.

In this embodiment, as shown in FIG. 5A, the central portion of the sound absorbing tube 1 in the axial direction is recessed toward the center of the silencer casing 3, but the silencer is reversed. A comparison is made with the sound-absorbing cylinder 51 having a configuration that is recessed toward the outer periphery of the casing 53.
As shown in FIG. 5B, in the sound absorbing tube 51, an annular concave portion 51a is formed on the inner peripheral surface of each muffler tube 51, and an annular protrusion 51b is formed on the outer peripheral surface. An annular recess 53a is formed on the inner peripheral surface of the silencer casing 53, and an annular protrusion 53b is formed on the outer peripheral surface of the silencer casing 53 to prevent an opening from being formed by the annular recess 53a. ing. Further, an annular projection 56b is formed on the outer peripheral surface of the cylindrical body 56 located at the center of the silencer casing 53.

In FIGS. 5A and 5B, the supercharger noise (sound wave) having a high frequency component introduced from the suction port of the supercharger into the contraction section 5 of the silencer travels straight while spreading radially, and goes straight. Is introduced into a passage 1c formed between the sound absorbing cylinders 1 and 1 in the inside.

In the sound-absorbing cylinder 1 of the present embodiment, the central portion of the silencer casing 3 in the axial direction is recessed toward the center of the silencer casing 3, so that the supercharger noise ( Sound wave)
When passing through, the turbocharger noise (sound wave) surely collides with the sound absorbing surface 1d of the annular concave portion 1a several times, and the energy of the sound is reduced. The sound absorbing material 14 is favorably absorbed to obtain a large silencing volume.

On the other hand, in the sound absorbing cylinder 51 shown in FIG. 5B, since the annular concave portion 51a of the sound absorbing cylinder 51 and the like is directed outward, the supercharger noise (sound wave) radially expanded at the contraction portion 55. Further expands in the passage 51c and enters the annular recess 51a and the like, so that the supercharger noise (sound wave) collides with the sound absorbing surface 51d of the annular recess 51a only once or twice. As a result, the absorption of sound energy by the sound absorbing material is reduced, and the silencing volume is also smaller than in the present embodiment of FIG. 5A.

5A and 5B, the sound absorbing cylinder 1 of this embodiment has a central portion in the axial direction recessed toward the center of the silencer casing 3. Accordingly, the external shape of the silencer can be reduced, and the size can be reduced. On the other hand, if the recess is directed outward as shown in FIG. 5B, the outer diameter of the silencer is increased by the amount of the annular projection 53b of the silencer casing 53, which restricts the arrangement and increases the cost. Tend.

FIG. 6 shows details of the interval between a pair of adjacent sound absorbing cylinders 1 and 1 in the embodiment of the silencer of the supercharger according to the present invention.

That is, in this embodiment, the passage width W between the annular concave portion 1a of the sound absorbing cylinder 1 and the annular protrusion 1b of the adjacent sound absorbing cylinder 1 is equal to the end of the pair of adjacent sound absorbing cylinders 1,1. The width is larger than the width W 'of the parallel passage near the portion. For this reason,.
The configuration of each sound absorbing cylinder 1 is such that the thickness dimension a at the center in the axial direction is smaller than the thickness dimension a ′ near the end.

According to such a structure, the flow velocity of the air flowing through the passage 1c 'at the central portion in the axial direction of the sound absorbing cylinder 1 is made slower than the flow velocity of the air flowing through the parallel passage 1c near the end in the axial direction. Pressure loss due to the bending of the air flow can be reduced.

Note that the present invention is not limited to the above-described embodiment, and various modifications can be made as necessary.

[0042]

As described above, according to the present invention, since the silencer has a circular cross section and the sound absorbing cylinders are arranged concentrically, there is no dead space for air flow, and the air flow is not biased. Air is sucked in efficiently. Also,
Since the curved portion is formed at the central portion in the axial direction of the sound absorbing cylinder, the entire sound absorbing area is also increased, and sound waves traveling straight through the passage formed between the sound absorbing cylinders collide on the sound absorbing surface, effectively reducing the energy of sound. And a large silencing volume can be obtained.

Further, by bending the central portion of the sound absorbing cylinder in the axial direction in this manner, the sound absorbing element portion can be made to have a short length, that is, a short depth, and a high-performance sound damping volume can be obtained. And, when the contraction part is provided, since the contraction is smoothly performed in a conical shape from the circular cross-section of the silencing element part to the circular cross-section of the coupling flange of the supercharger, it is shorter than the contraction part of the square front suction silencer. I can do it.

From the above, the depth of the silencer is reduced, the weight of the entire silencer is reduced, and the distance from the fitting flange of the supercharger supporting the entire weight of the silencer to the center of gravity of the silencer is reduced. Also, the vibration force acting on the coupling flange of the turbocharger is reduced, which is advantageous in strength.

Further, by making the width near the end portion larger than the width at the center portion of the sound absorbing cylinder, the flow rate of the air flowing through the recess at the center can be made slower than the flow rate of the air flowing near the end portion. Pressure loss due to bending of the dent can be reduced.

Further, since the sound absorbing cylinder has a configuration in which the central portion is depressed toward the center of the silencer casing, the silencing volume can be increased and the silencer can be made more compact.

[Brief description of the drawings]

1A is a partial sectional front view showing an embodiment of a silencer of a supercharger according to the present invention, and FIG. 1B is a sectional side view of FIG. 1A.

FIG. 2 is a sectional side view of the sound absorbing cylinder of FIG.

3 is a cross-sectional side view showing a concentric arrangement of the sound absorbing cylinders of the embodiment of FIG. 1, and FIG. 3B is a cross-sectional side view showing an arrangement of cylindrical sound absorbing cylinders.

FIG. 4 is a graph showing a relationship between a silencing volume and a band center frequency in both sound absorbing cylinders of FIG. 3;

5A is a schematic cross-sectional view of the silencer of FIG. 1, and FIG. 5B is a schematic cross-sectional view of a silencer having an annular projection formed outside the sound absorbing cylinder.

FIG. 6 is a sectional side view showing respective dimensions of the silencer of FIG. 1;

7A is a cross-sectional side view showing an example of a conventional cylindrical outer peripheral suction type silencer, and FIG. 7B is a schematic cross-sectional view of a cylindrical outer peripheral suction type silencer showing a flow of air in the silencer.

8A is a cross-sectional side view showing an example of a conventional square front suction type silencer, FIG. 8B is a front view showing the external shape of a supercharger and a silencer, and FIG. 8C is a side view schematically showing a square front suction type silencer.

FIG. 9 is a graph showing noise generated inside the turbocharger.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 sound-absorbing tube 1 a annular concave portion 1 b annular protrusion 1 c passage 1 d sound-absorbing surface 3 silencer casing 5 contraction section 9 sound-absorbing element section 10 silencer 11 partition plate 12 outer cylinder 13 inner cylinder 14 sound-absorbing material

[Procedure amendment]

[Submission date] June 21, 2000 (2006.2.
1)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction contents]

The discharge pressure of the supercharger is 3.5 kg / c.
Although it is about m ² G , if the pressure loss of the suction silencer attached to the suction port of the supercharger is small, the discharge pressure of the supercharger increases, and the efficiency of the supercharger increases. The efficiency of this turbocharger is 60-70%, and turbocharger manufacturers around the world are trying to achieve higher efficiencies in the 70% range.
It is generally said that reducing the pressure loss on the suction side by 10 mmAq improves the efficiency of the turbocharger by 1%. Therefore, for the suction silencer of the turbocharger, reducing the pressure loss is as important as increasing the silencing volume. In other words, by increasing the efficiency of the turbocharger,
The fuel efficiency of the engine is improved, which greatly contributes to fuel saving.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0030

[Correction method] Change

[Correction contents]

According to the simple cylindrical sound absorbing cylinder 21 described above, frequencies having wavelengths matching the arrangement pitch can be silenced to some extent, but silencing at other frequencies outside the pitch becomes extremely poor. I have. This is because in the simple cylindrical sound-absorbing cylinder 21, there occurs a phenomenon that frequencies other than the wavelength matching the pitch pass through without being absorbed. Here, the frequency of the wavelength that matches the arrangement pitch is the frequency of the wavelength that matches the arrangement pitch, assuming that the arrangement pitch of the sound absorbing cylinder 1 is 100 mm .
340 (m / s) from frequency = sound speed / wavelength (pitch)
/0.1 (m) = 3400 Hz. This frequency 34
The supercharger noise of 00 Hz is well absorbed, but as it goes away from this frequency, the absorption volume will decrease sharply.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Masahiro Kanazaki 960 Tokukura, Shimizu-cho, Sunto-gun, Shizuoka Prefecture 72) Inventor Yoshitsugu Aono 1-1-1, Akunoura-cho, Nagasaki City, Nagasaki Prefecture Inside Mitsubishi Heavy Industries, Ltd.Nagasaki Shipyards Terms (reference) 3G005 DA02 EA04 FA11 GB15

Claims (2)

[Claims] 1. A silencer of a supercharger which is attached to an air inlet of a supercharger and silences air sucked from outside a silencer casing. A silencer for a turbocharger, wherein sound absorbing cylinders, which are curved so that a central portion thereof is annularly concave toward the center, are arranged concentrically. 2. The silencer for a turbocharger according to claim 1, wherein a thickness dimension at a central portion in the axial direction of the sound absorbing cylinder is smaller than a thickness dimension near an end portion.