Supercharger silencer and supercharger

Abstract

This supercharger silencer can be attached to a compressor of a supercharger and comprises a pair of side walls and a plurality of first sound absorption splitters that are provided between the pair of side walls and are arranged with spaces therebetween in the circumferential direction around a predetermined central axis. In a cross section orthogonal to the central axis, the plurality of first sound absorption splitters extend along a plurality of straight lines that are radial with respect to the central axis.

Description

Supercharger silencer and supercharger

[0001] The present disclosure relates to a supercharger silencer and a supercharger. This application claims priority based on Japanese Patent Application No. 2025-016326 filed with the Japan Patent Office on February 3, 2025, and the content thereof is incorporated herein by reference.

[0002] Patent Document 1 discloses a supercharger silencer attachable to a compressor of a supercharger, which includes a pair of side walls and a plurality of sound-absorbing splitters provided between the pair of side walls and arranged at intervals in the circumferential direction around a predetermined central axis intersecting each of the pair of side walls. In the supercharger silencer disclosed in Patent Document 1, the shape of the sound-absorbing splitter in a cross section orthogonal to the central axis is formed along an involute curve.

[0003] Japanese Patent Application Laid-Open No. 2014-118832

[0004] When each of the plurality of sound-absorbing splitters has a shape along an involute curve like the supercharger silencer described in Patent Document 1, due to the complexity of the shape, the manufacturability of the sound-absorbing splitter and the supercharger silencer is likely to deteriorate, and the shape of the air flow path between adjacent sound-absorbing splitters is also complex, which is likely to cause an increase in pressure loss.

[0005] In view of the above circumstances, at least one embodiment of the present disclosure aims to provide a supercharger silencer with good manufacturability and capable of reducing pressure loss, and a supercharger including the same.

[0006] To achieve the above object, a supercharger silencer according to at least one embodiment of the present disclosure is a supercharger silencer attachable to a compressor of a supercharger, including a pair of side walls, and a plurality of first sound-absorbing splitters provided between the pair of side walls and arranged at intervals in the circumferential direction around a predetermined central axis. In a cross section orthogonal to the central axis, the plurality of first sound-absorbing splitters extend along a plurality of radial straight lines with the central axis as a reference.

[0007] According to at least one embodiment of the present disclosure, a silencer for a supercharger that is easy to manufacture and capable of reducing pressure loss, and a supercharger equipped with the same are provided.

[0008] This is a side view showing the schematic configuration of a supercharger 100 according to one embodiment. This is a schematic cross-sectional view showing a cross-section perpendicular to the central axis C in a supercharger silencer 8A according to one embodiment. This is a schematic cross-sectional view showing a cross-section perpendicular to the central axis C in a supercharger silencer 8B according to another embodiment. This is a schematic cross-sectional view showing a cross-section perpendicular to the central axis C in a supercharger silencer 8C according to yet another embodiment. This is a schematic cross-sectional view showing a cross-section perpendicular to the central axis C in a supercharger silencer 8D according to yet another embodiment. This is a schematic cross-sectional view showing a cross-section perpendicular to the central axis C in a supercharger silencer 8E according to yet another embodiment. This is a schematic cross-sectional view showing a cross-section perpendicular to the central axis C in a supercharger silencer 8F according to yet another embodiment. This is a schematic cross-sectional view showing a cross-section perpendicular to the central axis C in a supercharger silencer 8G according to yet another embodiment. This is a schematic cross-sectional view showing a cross-section perpendicular to the central axis C in a supercharger silencer 8H according to yet another embodiment. This is a graph of noise reduction information showing the relationship between d / λ and the noise reduction per unit length d of the air passage 9 for each opening area ratio. This figure compares the predicted results (predicted relationship between frequency and noise reduction) of the noise reduction performance of the turbocharger silencer 8A, calculated using Dolling's method, with the test results of the relationship between frequency and noise reduction. It also shows the relationship between frequency and noise reduction for each of the turbocharger silencers 8A and 8B.

[0009] Hereinafter, several embodiments of this disclosure will be described with reference to the attached drawings. However, the dimensions, materials, shapes, relative arrangements, etc., of the components described as embodiments or shown in the drawings are not intended to limit the scope of the invention, but are merely illustrative examples. For example, expressions describing relative or absolute arrangements such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial" should not only strictly represent such arrangements, but also represent states where there is a tolerance, or a relative displacement of an angle or distance sufficient to achieve the same function. For example, expressions describing things as being in an equal state such as "identical," "equal," and "homogeneous" should not only strictly represent states of equality, but also represent states where there is a tolerance, or a difference sufficient to achieve the same function. For example, expressions describing shapes such as a square shape or a cylindrical shape should not only represent geometrically precise shapes such as square shapes or cylindrical shapes, but also represent shapes including concave and concave parts, chamfered parts, etc., to the extent that the same effect can be achieved. On the other hand, expressions such as "to possess," "to be equipped with," "to have," "to include," or "to have" a single component are not exclusive expressions that exclude the existence of other components.

[0010] Figure 1 is a side view showing a schematic configuration of a supercharger 100 according to one embodiment. As shown in Figure 1, the supercharger 100 comprises a turbine 2, a compressor 4, a bearing base 6, and a supercharger silencer 8.

[0011] The turbine 2 comprises a turbine rotor 10 that rotates using exhaust gas emitted from an internal combustion engine (not shown), and a turbine housing 12 that houses the turbine rotor 10. The internal combustion engine may be, for example, a large marine diesel engine.

[0012] The compressor 4 is a centrifugal compressor that is driven by the rotation of the turbine rotor 10 and comprises an impeller 14 that compresses the intake air to the internal combustion engine, and a compressor housing 16 that houses the impeller 14.

[0013] The bearing base 6 is located between the turbine 2 and the compressor 4 and houses a bearing device 20 that rotatably supports a rotating shaft 18 connecting the turbine rotor 10 of the turbine 2 and the impeller 14 of the compressor 4. The bearing base 6 is placed on the ground g and is configured to support at least a portion of the load of the supercharger 100.

[0014] The supercharger silencer 8 is attached to the air intake 5 of the compressor 4 to reduce noise emitted from the air intake 5 of the compressor 4. The supercharger silencer 8 includes a pair of side walls 24, 26 and a plurality of first sound-absorbing splitters 28A provided between the pair of side walls 24, 26. Each of the plurality of first sound-absorbing splitters 28A is formed in the shape of a flat plate or a substantially plate and is made of a sound-absorbing material. Each of the plurality of first sound-absorbing splitters 28A may include, for example, glass wool and glass cloth wrapping the glass wool as the sound-absorbing material. In the exemplary embodiment shown in Figure 1, the supercharger silencer 8 has a substantially cylindrical shape, and each of the pair of side walls 24, 26 has a disc shape. The central axis C of the supercharger silencer 8 may coincide with the rotation axis of the impeller 14 of the compressor 4.

[0015] The portion of the supercharger silencer 8 corresponding to its outer circumferential surface (the gap between the outer edge of the side wall 24 and the outer edge of the side wall 26) forms an opening 30 around its entire circumference. Air flowing from the outer circumferential side of the supercharger silencer 8 through the opening 30 into the space between the pair of side walls 24 and 26 passes between a plurality of first sound-absorbing splitters 28A and is then introduced to the impeller 14 of the compressor 4 through a through-hole 32 formed in the center of the side wall 26 on the compressor 4 side. As shown in Figure 1, the opening 30 may be provided with a filter 31 to prevent foreign matter from entering the inside of the supercharger silencer 8.

[0016] In this specification, unless otherwise specified, "axial direction" means the direction parallel to the central axis C of the turbocharger silencer 8 (i.e., the axial direction of the impeller 14), unless otherwise specified, "circumferential direction" means the circumferential direction around the central axis C of the turbocharger silencer 8 (i.e., the circumferential direction of the impeller 14), and unless otherwise specified, "radial direction" means the radial direction with respect to the central axis C of the turbocharger silencer 8 (i.e., the radial direction of the impeller 14).

[0017] Next, several embodiments of the turbocharger silencer 8, specifically the turbocharger silencers 8A to 8H, will be described using Figures 2 to 9. Figure 2 is a schematic cross-sectional view showing a cross-section perpendicular to the central axis C in the turbocharger silencer 8A according to one embodiment. Figure 3 is a schematic cross-sectional view showing a cross-section perpendicular to the central axis C in the turbocharger silencer 8B according to another embodiment. Figure 4 is a schematic cross-sectional view showing a cross-section perpendicular to the central axis C in the turbocharger silencer 8C according to yet another embodiment. Figure 5 is a schematic cross-sectional view showing a cross-section perpendicular to the central axis C in the turbocharger silencer 8D according to yet another embodiment. Figure 6 is a schematic cross-sectional view showing a cross-section perpendicular to the central axis C in the turbocharger silencer 8E according to yet another embodiment. Figure 7 is a schematic cross-sectional view showing a cross-section perpendicular to the central axis C in the turbocharger silencer 8F according to yet another embodiment. Figure 8 is a schematic cross-sectional view showing a cross-section perpendicular to the central axis C in the turbocharger silencer 8G according to yet another embodiment. Figure 9 is a schematic cross-sectional view showing a cross-section perpendicular to the central axis C in a turbocharger silencer 8H according to yet another embodiment. Note that in Figures 4 to 9, some areas in the circumferential direction of turbocharger silencers 8C to 8H are not shown.

[0018] In some embodiments, as shown in Figures 2 to 9, for example, the multiple first sound-absorbing splitters 28A are arranged circumferentially at intervals around the central axis C. Furthermore, the multiple first sound-absorbing splitters 28A each extend along multiple radial lines Lr (multiple radial lines in the illustrated example) with respect to the central axis C in a cross section perpendicular to the central axis C. An air passage 9 is formed between two adjacent first sound-absorbing splitters 28A, and air passing through the air passage 9 from the outer circumference of the supercharger silencer 8 is guided to the compressor 4.

[0019] In some exemplary embodiments shown in Figures 2 to 9, in a cross-section perpendicular to the central axis C, if we define the position of the outer end 34 of each of the multiple first sound-absorbing splitters 28A in the radial direction as the outer end position P1 and the position of the inner end 36 of each of the multiple first sound-absorbing splitters 28A in the radial direction as the inner end position P2, then each of the multiple first sound-absorbing splitters 28A extends along a straight line in the radial direction from the outer end position P1 to the inner end position P2. Furthermore, each of the multiple first sound-absorbing splitters 28A is configured such that the line segment La connecting the outer end position P1 and the inner end position P2 does not extend beyond the first sound-absorbing splitter 28A.

[0020] In some embodiments, as shown in Figures 2, 3, 8, and 9, for example, a plurality of first sound-absorbing splitters 28A are arranged at equal intervals in the circumferential direction.

[0021] In some embodiments, as shown in Figures 2, 5, 8, and 9, for example, each of the multiple first sound-absorbing splitters 28A is formed in a flat plate shape. In some exemplary embodiments shown in Figures 2, 5, 8, and 9, each of the multiple first sound-absorbing splitters 28A includes a constant thickness portion 33 having a constant thickness w regardless of its radial position, an outer end portion 38 whose thickness w decreases as it extends radially outward from the constant thickness portion 33, and an inner end portion 40 whose thickness w decreases as it extends radially inward from the constant thickness portion 33. In each of the multiple first sound-absorbing splitters 28A, the direction of the thickness w of the first sound-absorbing splitter 28A is perpendicular to the line segment La in the first sound-absorbing splitter 28A (perpendicular to the radial direction at the position of the first sound-absorbing splitter 28A).

[0022] In some embodiments, as shown in Figures 3 and 6, for example, each of the multiple first sound-absorbing splitters 28A includes a thickness-increasing portion 35 whose thickness w increases as it extends radially outward. In each of the multiple first sound-absorbing splitters 28A, the thickness-increasing portion 35 may occupy more than half of the radial area of ​​the first sound-absorbing splitter 28A. In this case as well, in each of the multiple first sound-absorbing splitters 28A, the direction of the thickness w of the first sound-absorbing splitter 28A is perpendicular to the line segment La in the first sound-absorbing splitter 28A (a direction perpendicular to the radial direction at the position of the first sound-absorbing splitter 28A).

[0023] In the exemplary embodiments shown in Figures 3 and 6, in a cross-section perpendicular to the central axis C, the contour of the first sound-absorbing splitter 28A is defined by a pair of straight lines 52 and 53 whose distance from each other increases as they extend radially outward, a convex curve 55 connecting the radially outer ends of each of the pair of line segments, and a convex curve 56 connecting the radially inner ends of each of the pair of line segments 52 and 53. In this case, in a cross-section perpendicular to the central axis C, the radially outer end 38 of the first sound-absorbing splitter 28A is the portion enclosed by the convex curve 55 and a hypothetical line segment connecting both ends of the convex curve 55, and the radially inner end 40 of the first sound-absorbing splitter 28A is the portion enclosed by the convex curve 56 and a hypothetical line segment connecting both ends of the convex curve 56.

[0024] In some embodiments, as shown in Figure 3, for example, an air passage 9 having a constant flow path width d independent of the radial position is formed between two adjacent first sound-absorbing splitters 28A in a plurality of first sound-absorbing splitters 28A, and the air passage 9 extends along a radial straight line in a cross section perpendicular to the central axis C.

[0025] In some embodiments, as shown in Figure 4, for example, the turbocharger silencer 8C includes a plurality of second sound-absorbing splitters 28B, each having only one bend 41. The plurality of second sound-absorbing splitters 28B are arranged circumferentially together with the plurality of first sound-absorbing splitters 28A. In the exemplary embodiment shown in Figure 4, in each of the plurality of second sound-absorbing splitters 28B, the portion 42 inside the bend 41 in the radial direction of the second sound-absorbing splitter 28B extends along a radial line in a cross section perpendicular to the central axis C, and the portion 44 outside the bend 41 in the radial direction extends along a linear inclined with respect to the radial direction in a cross section perpendicular to the central axis C. In the exemplary embodiment shown in Figure 4, the number of first sound-absorbing splitters 28A provided by the turbocharger silencer 8 is greater than the number of second sound-absorbing splitters 28B provided by the turbocharger silencer 8. Furthermore, in the exemplary configuration shown in Figure 4, multiple first sound-absorbing splitters 28A are arranged between any two second sound-absorbing splitters 28B in the multiple second sound-absorbing splitters 28.

[0026] In some embodiments, as shown in Figures 5 to 7, for example, the plurality of first sound-absorbing splitters 28A are arranged at unequal pitches in the circumferential direction. In this case, as shown in Figures 5 and 6, for example, if the thickness of the inner end 40 of each of the plurality of first sound-absorbing splitters 28A in the radial direction is w1, and the maximum value of the distance d between two adjacent first sound-absorbing splitters 28A in the circumferential direction is dmax, and the minimum value of the distance d between two adjacent first sound-absorbing splitters 28A in the circumferential direction is dmin, then the plurality of first sound-absorbing splitters 28A may be arranged such that w1 / 2 ≤ dmin and dmax ≤ 4w1. In the exemplary embodiment shown in Figure 5, the thickness w1 of the inner end 40 is equal to the thickness of the constant-thickness portion 33, and in the exemplary embodiment shown in Figure 6, the thickness w1 of the inner end 40 represents the minimum distance between the pair of straight lines 52, 53.

[0027] In some embodiments, as shown in Figure 7, for example, at least one of the plurality of first sound-absorbing splitters 28A may include a flat plate portion 60 and a thickness-increasing portion 62 connected to the outer end of the flat plate portion 60 in the radial direction, the thickness w of which increases as it extends outward in the radial direction. In this case as well, in each of the plurality of first sound-absorbing splitters 28A, the direction of the thickness w of the first sound-absorbing splitter 28A is perpendicular to the line segment La in the first sound-absorbing splitter 28A (perpendicular to the radial direction at the position of the first sound-absorbing splitter 28A).

[0028] In some embodiments, as shown in Figures 8 and 9, for example, the plurality of first sound-absorbing splitters 28A include a plurality of first sound-absorbing splitters 28A of different radial lengths.

[0029] In the exemplary configuration shown in Figure 8, the plurality of first sound-absorbing splitters 28A include two types of first sound-absorbing splitters 28A having different radial lengths, and the first sound-absorbing splitter 28A with the longer radial length and the first sound-absorbing splitter 28A with the shorter radial length are alternately arranged in the circumferential direction.

[0030] In the exemplary configuration shown in Figure 9, the plurality of first sound-absorbing splitters 28A include three types of first sound-absorbing splitters 28A having different radial lengths. Furthermore, if we define a first sound-absorbing splitter set 58 as four first sound-absorbing splitters 28A arranged in circumferential order, each consisting of the first sound-absorbing splitter 28A with the longest radial length among the three types of first sound-absorbing splitters 28A, the first sound-absorbing splitter 28A with the shortest radial length among the three types of first sound-absorbing splitters 28A, the first sound-absorbing splitter 28A with an intermediate radial length among the three types of first sound-absorbing splitters 28A, and the first sound-absorbing splitter 28A with the shortest radial length among the three types of first sound-absorbing splitters 28A, then a plurality of first sound-absorbing splitter sets 58 are arranged in the circumferential direction.

[0031] Here, the effects of the above-described turbocharger silencers 8A to 8H will be explained. In the above-described turbocharger silencers 8A to 8H, in a cross section perpendicular to the central axis C, a plurality of first sound-absorbing splitters 28A extend along a plurality of radial straight lines La with respect to the central axis C. Compared to the case where each of the plurality of first sound-absorbing splitters has a shape along an involute curve (for example, the turbocharger silencer shown in Patent Document 1), the shape of each of the first sound-absorbing splitters 28A can be made simple (for example, a flat plate shape or a shape close to a flat plate shape), and the shape of the air passage 9 formed between two adjacent first sound-absorbing splitters 28A can also be made simple. As a result, a turbocharger silencer 8 with good manufacturability and reduced pressure loss can be realized, and the decrease in efficiency of the turbocharger 100 caused by pressure loss can be suppressed. Furthermore, as described above, the shape of each of the multiple first sound-absorbing splitters 28A can be made simple. For example, if the first sound-absorbing splitter 28A is manufactured by filling the inside with sound-absorbing material (for example, glass wool wrapped in glass cloth), filling with sound-absorbing material becomes easier, thus improving manufacturability.

[0032] Furthermore, as described above, the shape of each of the first sound-absorbing splitters 28A can be made simple, making it possible to accurately predict the noise reduction performance of the supercharger silencers 8A to 8H. Therefore, there is no need to take excessive noise countermeasures, and the thickness and material of the first sound-absorbing splitters 28A can be optimized to obtain the necessary noise reduction performance, thereby reducing the cost required to obtain the necessary noise reduction performance.

[0033] For example, when using Doelling's noise reduction calculation method for the supercharger silencer 8A, the ratio of the opening area at the inlet position of the air passage 9 in the radial direction (the ratio of the opening to the cylindrical surface with respect to the central axis C) can be calculated using the air passage width d of the air passage 9 and the thickness w of the first sound-absorbing splitter. Based on the calculated opening area ratio, the air passage width d, the length of the first sound-absorbing splitter 28A (the radial length in the example shown in Figure 2), the wavelength λ to be predicted for noise reduction, and known noise reduction information (see Figure 10), the relationship between the frequency of the supercharger silencer 8A and the noise reduction can be calculated. The graph shown in Figure 10 is an example of noise reduction information showing the relationship between d / λ and the noise reduction per unit length d of the air passage 9 for each opening area ratio.

[0034] However, in the general calculation method for noise reduction by Dolling, a duct with a constant flow path cross-sectional area is assumed. Therefore, in cases where the flow path cross-sectional area of ​​the air passage 9 decreases towards the inside in the radial direction, such as in the turbocharger silencer 8A, the length of the first sound-absorbing splitter 28A may be calculated by multiplying the actual length of the first sound-absorbing splitter 28A by a predetermined correction coefficient. In contrast, in the turbocharger silencer 8B shown in Figure 3, the flow path width d of the air passage 9 is constant regardless of the radial position (i.e., the flow path cross-sectional area of ​​the air passage 9 is constant regardless of the radial position), so the noise reduction performance of the turbocharger silencer 8 can be accurately predicted without using such a correction coefficient.

[0035] Figure 11 shows a comparison between the predicted results (predicted relationship between frequency and noise reduction) of the noise reduction performance of the turbocharger silencer 8A, which were predicted using Doelling's calculation method, and the test results of the relationship between frequency and noise reduction. As illustrated in Figure 11, since the shape of each of the first sound-absorbing splitters 28A in the turbocharger silencers 8A to 8H is simple, it is possible to accurately predict the noise reduction performance of the turbocharger silencers 8A to 8H.

[0036] Figure 12 shows the relationship between frequency and noise reduction for each of the turbocharger silencers 8A and 8B. As illustrated in Figure 12, in the turbocharger silencers 8B, 8E, and 8F, the thickness w of each of the multiple first sound-absorbing splitters 28A changes according to their radial position, which changes the peak frequency of the sound absorption coefficient, making it possible to obtain a higher noise reduction effect over a wider frequency band compared to the turbocharger silencer 8A. In addition, since the thickness increases towards the outside in the radial direction, it is possible to suppress the abrupt decrease in the cross-sectional area of ​​the airflow path between two adjacent first sound-absorbing splitters according to their radial position.

[0037] This disclosure is not limited to the embodiments described above, but also includes modified forms of the embodiments described above, as well as forms that combine these forms as appropriate.

[0038] For example, in some embodiments, the supercharger silencer 8 may include, along with the plurality of first sound-absorbing splitters 28A described above, at least one sound-absorbing splitter having a different shape. In this case, the at least one sound-absorbing splitter having a different shape may include a sound-absorbing splitter that extends along an involute curve in a cross section perpendicular to the central axis C, or a Z-shaped sound-absorbing splitter having two bends, or both.

[0039] Furthermore, in the exemplary embodiment shown in Figure 4, the turbocharger silencer 8C included a plurality of second sound-absorbing splitters 28B, but the number of second sound-absorbing splitters 28B provided in the turbocharger silencer 8C may be just one.

[0040] Furthermore, the sound-absorbing material used in the first sound-absorbing splitter 28A and the second sound-absorbing splitter 28B is not limited to the aforementioned glass wool, but may also be, for example, a polyester board made by heat-welding polyester fibers together to form a soft plate, and is not particularly limited.

[0041] The contents described in each of the above embodiments can be understood, for example, as follows:

[0042] [1] A supercharger silencer according to at least one embodiment of the present disclosure (for example, the supercharger silencers 8, 8A to 8H described above) is a supercharger silencer that can be attached to a compressor (for example, the compressor 4 described above) of a supercharger (for example, the supercharger 100 described above), comprising: a pair of side walls (for example, the pair of side walls 24, 26 described above); and a plurality of first sound-absorbing splitters (for example, the plurality of first sound-absorbing splitters 28A described above) provided between the pair of side walls and arranged at circumferential intervals around a predetermined central axis (for example, the central axis C described above), wherein in a cross section perpendicular to the central axis, the plurality of first sound-absorbing splitters extend along a plurality of radial straight lines (for example, the plurality of straight lines Lr described above) with respect to the central axis.

[0043] According to the turbocharger silencer described in [1] above, in a cross-section perpendicular to the central axis, the multiple first sound-absorbing splitters extend along multiple radial lines with respect to the central axis. Therefore, compared to the case where each of the multiple first sound-absorbing splitters has a shape along an involute curve, the shape of each first sound-absorbing splitter can be made simpler, and the shape of the flow path formed between two adjacent first sound-absorbing splitters can also be made simpler. As a result, a turbocharger silencer with good manufacturability and reduced pressure loss can be realized.

[0044] [2] In some embodiments, in the supercharger silencer described in [1] above, in a cross-section orthogonal to the central axis, for each of the plurality of first sound-absorbing splitters, the position of the outer end of the first sound-absorbing splitter in the radial direction with respect to the central axis is defined as the outer end position (for example, the outer end position P1 described above), and the position of the inner end of the first sound-absorbing splitter in the radial direction is defined as the inner end position (for example, the inner end position P2 described above). Then, each of the plurality of first sound-absorbing splitters extends along a straight line from the outer end position to the inner end position.

[0045] According to the supercharger silencer described in [2] above, the shape of each of the first sound-absorbing splitters can be made into a simple shape, and the shape of the flow path formed between two adjacent first sound-absorbing splitters can also be made into a simple shape. Therefore, it is possible to realize a supercharger silencer with good manufacturability and capable of reducing pressure loss.

[0046] [3] In some embodiments, in the supercharger silencer described in [1] or [2] above, in a cross-section orthogonal to the central axis, for each of the plurality of first sound-absorbing splitters, the position of the outer end of the first sound-absorbing splitter in the radial direction with respect to the central axis is defined as the outer end position (for example, the outer end position P1 described above), and the position of the inner end of the first sound-absorbing splitter in the radial direction is defined as the inner end position (for example, the inner end position P2 described above). Then, each of the plurality of first sound-absorbing splitters is configured such that a line segment connecting the outer end position and the inner end position (for example, the line segment La described above) does not protrude from the first sound-absorbing splitter.

[0047] According to the supercharger silencer described in [3] above, the shape of each of the first sound-absorbing splitters can be made into a simple shape, and the shape of the flow path formed between two adjacent first sound-absorbing splitters can also be made into a simple shape. Therefore, it is possible to realize a supercharger silencer with good manufacturability and capable of reducing pressure loss.

[0048] [4] In some embodiments, in the supercharger silencer according to any one of [1] to [3] above, each of the plurality of first sound-absorbing splitters is formed in a flat plate shape.

[0049] According to the supercharger silencer described in [4] above, the shape of each of the first sound-absorbing splitters is a simple shape, and the shape of the flow path formed between two adjacent first sound-absorbing splitters is also a simple shape. For this reason, it is possible to realize a supercharger silencer with good manufacturability and reduced pressure loss.

[0050] [5] In some embodiments, in the supercharger silencer according to any one of [1] to [4] above, each of the plurality of first sound-absorbing splitters includes a thickness increasing portion formed so that the thickness (for example, the above-described thickness w) increases as it goes outward in the radial direction with respect to the central axis.

[0051] According to the supercharger silencer described in [5] above, by changing the thickness of each of the plurality of first sound-absorbing splitters according to the position in the radial direction, the peak frequency of the sound absorption rate changes, and high sound reduction in a wide frequency band can be obtained. Further, since the thickness increases as it goes outward in the radial direction, it is possible to suppress a rapid decrease in the flow path cross-sectional area of the air flow path between two adjacent first sound-absorbing splitters according to the position in the radial direction.

[0052] [6] In some embodiments, in the supercharger silencer according to [5] above, between two adjacent first sound-absorbing splitters among the plurality of first sound-absorbing splitters, an air flow path (for example, the above-described air flow path 9) having a constant flow path width (for example, the above-described flow path width d) that does not depend on the position in the radial direction is formed, and the air flow path extends along a straight line in a cross section orthogonal to the central axis.

[0053] According to the supercharger silencer described in [6] above, since the flow path width of the air flow path between two adjacent first sound-absorbing splitters is constant in the radial direction, it is easy to accurately predict the sound reduction performance of the supercharger silencer using a known calculation formula such as Doelling's formula.

[0054] [7] In some embodiments, the supercharger silencer described in any of [1] to [6] further comprises at least one second sound-absorbing splitter (for example, the plurality of second sound-absorbing splitters 28B described above) arranged in the circumferential direction together with the plurality of first sound-absorbing splitters and having only one bent portion (for example, the bent portion 41 described above).

[0055] According to the supercharger silencer described in [7] above, the noise reduction effect can be improved by the diffraction effect of the bent portion. In addition, since the second sound-absorbing splitter has only one bent portion, the decrease in the accuracy of predicting the noise reduction performance can be suppressed compared to the case where there are two or more bent portions.

[0056] [8] In some embodiments, in the supercharger silencer described in any of [1] to [7] above, the plurality of first sound-absorbing splitters are arranged at unequal pitches in the circumferential direction.

[0057] The supercharger silencer described in [8] above can widen the frequency range over which a noise reduction effect can be obtained, compared to the case where multiple first sound-absorbing splitters are arranged at equal pitches in the circumferential direction.

[0058] [9] In some embodiments, in the supercharger silencer described in [8] above, if the thickness of the inner end of each of the plurality of first sound-absorbing splitters in the radial direction with respect to the central axis is w1, and the maximum value of the distance between two adjacent first sound-absorbing splitters in the circumferential direction is dmax, and the minimum value of the distance between two adjacent first sound-absorbing splitters in the circumferential direction is dmin, then the plurality of first sound-absorbing splitters are arranged such that w1 / 2 ≤ dmin and dmax ≤ 4w1.

[0059] The supercharger silencer described in [9] above suppresses interference between two adjacent first sound-absorbing splitters while suppressing a decrease in noise reduction performance.

[0060]

[10] In some embodiments, the supercharger silencer described in any of [1] to [9] above, the plurality of first sound-absorbing splitters include a plurality of first sound-absorbing splitters of different radial lengths with respect to the central axis.

[0061] According to the supercharger silencer described in

[10] above, by appropriately setting the lengths of multiple types of first sound-absorbing splitters (for example, by making the difference between the length of one of two circumferentially adjacent first sound-absorbing splitters equal to 1 / 4 of a specific wavelength for which the sound reduction effect is to be enhanced), the reflected waves from two circumferentially adjacent first sound-absorbing splitters interfere with and cancel each other out, thereby improving the sound reduction effect at that specific wavelength (i.e., the sound reduction effect at a specific frequency).

[0062]

[11] A supercharger according to at least one embodiment of the present disclosure comprises a turbine (e.g., the turbine 2 described above), a compressor (e.g., the compressor 4 described above), and a supercharger silencer as described in any of [1] to

[10] above.

[0063] According to the supercharger described in

[11] above, it is possible to realize a supercharger equipped with a supercharger silencer that is easy to manufacture and can reduce pressure loss.

[0064] 2: Turbine 4: Compressor 5: Air intake 6: Bearing base 8 (8A-8H): Silencer for supercharger 10: Turbine rotor 12: Turbine housing 14: Impeller 16: Compressor housing 18: Rotating shaft 20: Bearing device 24: Side wall 26: Side wall 28: Sound-absorbing splitter 28A: First sound-absorbing splitter 28B: Second sound-absorbing splitter 30: Opening 31: Filter 32: Through hole 34: Outer end 36: Inner end 38: Outer end 40: Inner end 41: Bent section 55: Convex curve 56: Convex curve 58: First sound-absorbing splitter set 60: Flat section 62: Thickness increase section 100: Supercharger

Claims

1. A supercharger silencer that can be attached to the compressor of a supercharger, comprising: a pair of side walls; and a plurality of first sound-absorbing splitters provided between the pair of side walls and arranged at circumferential intervals around a predetermined central axis, wherein in a cross section perpendicular to the central axis, the plurality of first sound-absorbing splitters extend along a plurality of radial straight lines with respect to the central axis.

2. In a cross section perpendicular to the central axis, for each of the plurality of first sound-absorbing splitters, the position of the outer end of the first sound-absorbing splitter in the radial direction with respect to the central axis is defined as the outer end position, and the position of the inner end of the first sound-absorbing splitter in the radial direction is defined as the inner end position, and each of the plurality of first sound-absorbing splitters extends in a straight line from the outer end position to the inner end position, as described in claim 1.

3. In a cross section perpendicular to the central axis, for each of the plurality of first sound-absorbing splitters, the position of the outer end of the first sound-absorbing splitter in the radial direction with respect to the central axis is defined as the outer end position, and the position of the inner end of the first sound-absorbing splitter in the radial direction is defined as the inner end position, and each of the plurality of first sound-absorbing splitters is configured such that the line segment connecting the outer end position and the inner end position does not extend beyond the first sound-absorbing splitter, as described in claim 1.

4. The supercharger silencer according to claim 1, wherein each of the plurality of first sound-absorbing splitters is formed in the shape of a flat plate.

5. The supercharger silencer according to claim 1, wherein each of the plurality of first sound-absorbing splitters includes a thickness-increasing portion formed such that its thickness increases outward in the radial direction with respect to the central axis.

6. The supercharger silencer according to claim 5, wherein an air passage having a constant flow width independent of the radial position is formed between two adjacent first sound-absorbing splitters in the plurality of first sound-absorbing splitters, and the air passage extends along a straight line in a cross section perpendicular to the central axis.

7. The supercharger silencer according to claim 1, further comprising at least one second sound-absorbing splitter arranged circumferentially together with the plurality of first sound-absorbing splitters and having only one bend.

8. The supercharger silencer according to claim 1, wherein the plurality of first sound-absorbing splitters are arranged at unequal pitches in the circumferential direction.

9. The silencer for a supercharger according to claim 8, wherein the thickness of the inner end of each of the plurality of first sound-absorbing splitters in the radial direction with respect to the central axis is w1, the maximum distance between two adjacent first sound-absorbing splitters in the circumferential direction is dmax, and the minimum distance between two adjacent first sound-absorbing splitters in the circumferential direction is dmin, and the plurality of first sound-absorbing splitters are arranged such that w1 / 2 ≤ dmin and dmax ≤ 4w1.

10. The supercharger silencer according to claim 1, wherein the plurality of first sound-absorbing splitters include a plurality of types of first sound-absorbing splitters having different radial lengths with respect to the central axis.

11. A supercharger comprising a turbine, a compressor, and a supercharger silencer according to any one of claims 1 to 10.

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