Silencer made of resin

Abstract

To provide a resin silencer connected to a pipe of an air conditioner for an automobile and having excellent silencing performance while securing sufficient pressure resistance in spite of light weight.SOLUTION: A cylindrical barrel portion 2 and smaller-diameter pipe portions 5 and 6 disposed at both end portions of the barrel portion 2 in a cylinder axis direction are connected to each other via cylindrical expanded-diameter portions 3 and 4 in which an outer peripheral surface 3b portion and a 4b portion are expanded toward the barrel portion 2, and at least one expanded-diameter portion 3 includes an inner protruding portion 7 having an inner flow path 8 that is continuous with a flow path 5a portion of the connected pipe portion 5 and protrudes in the cylinder axis direction of the pipe portion 5 toward the barrel portion 2. A position in the cylinder axial direction of a projecting tip 7t of the internal projecting part 7 is set in the vicinity of a boundary in the cylinder axial direction between the diameter-enlarged part 3 and the barrel part 2, a refrigerant R is made to flow into the barrel part 2 through a flow passage 5a of one pipe part 5 and the internal flow passage 8, and the refrigerant R is made to flow out of the barrel part 2 through a flow passage 6a of the other pipe part 6.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a resin silencer that is connected to the piping of an automotive air conditioner. [Background technology]

[0002] A silencer is connected to the piping of an automobile air conditioner to suppress noise caused by the flow of circulating refrigerant (see, for example, Patent Document 1). The silencer is a cylindrical body with a larger diameter than the piping to which it is connected, and is mainly made of metal.

[0003] In order to reduce pulsation, a structure has also been proposed in which a connecting pipe connected to an inlet-side small diameter portion provided on the muffler body is inserted deep inside the muffler body (see Patent Document 2). In the structure proposed in Patent Document 2, the tip of the connecting pipe (inner pipe) is positioned near the longitudinal center of the muffler body (paragraph 0012, etc.), and the muffler is made of metal (paragraph 0027). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-205701 [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-12869 Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, with the trend toward lighter automobiles, there has been a demand for lighter piping. When replacing conventional metal silencers with resin silencers to reduce weight, it is necessary to ensure sufficient pressure resistance against the internal pressure exerted by the refrigerant flowing through the silencer. For example, in a structure in which a thin-diameter pipe is simply connected to a thick-diameter cylindrical portion of a silencer, excessive internal pressure acts at the portion where the diameter changes suddenly, making it difficult to ensure sufficient pressure resistance with a resin silencer. Furthermore, a structure in which the inner pipe is made longer to improve sound deadening performance, as proposed in Patent Document 2, is disadvantageous in terms of reducing weight. Therefore, there is room for improvement in order to realize a resin silencer that is lightweight yet has sufficient pressure resistance against internal pressure and excellent sound deadening performance.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a resin silencer that is connected to the piping of an automotive air conditioner, is lightweight, has sufficient pressure resistance against internal pressure, and has excellent sound-absorbing performance. [Means for solving the problem]

[0007] In order to achieve the above object, the resin silencer of the present invention has a cylindrical body portion, pipe portions having a smaller diameter than the body portion and arranged at both ends of the body portion in the axial direction, and cylindrical expanded diameter portions connected between each of the pipe portions and the body portion and having an outer circumferential surface expanding in diameter toward the body portion, and each of the pipe portions is connected to the piping of an automotive air conditioner, and at least one of the expanded diameter portions has an internal protruding portion having an internal flow path that is continuous with the flow path of the connected pipe portion and protrudes in the axial direction of the pipe portion toward the body portion, and the axial position of the protruding tip of the internal protruding portion is set near the axial boundary between this expanded diameter portion and the body portion, and refrigerant flows into the body portion through the internal flow path. [Effects of the Invention]

[0008] According to the present invention, the silencer is made of resin, which is extremely advantageous in terms of reducing its weight compared to conventional metal silencers. Furthermore, by connecting the body portion and the smaller-diameter pipe portion via the cylindrical enlarged-diameter portion whose outer circumferential surface expands toward the body portion, it is possible to avoid localized excessive stress when internal pressure acts on the silencer, thereby ensuring sufficient pressure resistance. Furthermore, by providing the internal protrusion on at least one of the enlarged-diameter portions, the cross-sectional area through which the refrigerant flows increases sharply at the protruding tip of the internal flow passage, causing the refrigerant to flow radially from the protruding tip of the internal flow passage into the body portion, thereby achieving excellent sound-absorbing performance. Furthermore, because the protruding tip of the internal protrusion is positioned near the axial boundary between the enlarged-diameter portion and the body portion, weight increase due to the internal protrusion is suppressed. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is an explanatory diagram illustrating an embodiment of a silencer in a vertical cross-sectional view. FIG. [Figure 2] FIG. 2 is an enlarged view of a portion of FIG. [Figure 3] 3 is a cross-sectional view taken along the line AA in FIG. 2. [Figure 4] FIG. 10 is an explanatory diagram illustrating another embodiment of the silencer in a partially enlarged cross-sectional view. [Figure 5] 5 is a cross-sectional view of FIG. 4 taken along line B-B. [Figure 6] FIG. 10 is an explanatory diagram illustrating another embodiment of the silencer in a partially enlarged cross-sectional view. [Figure 7] 7 is a cross-sectional view taken along CC in FIG. 6. [Figure 8] FIG. 10 is an explanatory diagram illustrating another embodiment of the silencer in a vertical cross-sectional view. [Figure 9] 10 is an explanatory diagram illustrating another embodiment of a silencer in which the arrangement of the pipe portions is different, as viewed in vertical section. FIG. [Figure 10] 10 is an explanatory diagram illustrating, in vertical cross section, still another embodiment of a silencer in which the arrangement of the pipe portions is different. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A resin silencer according to the present invention will now be described with reference to the embodiments shown in the drawings.

[0011] 1 to 3 has a cylindrical body 2, an inlet-side pipe section 5 and an outlet-side pipe section 6 disposed at both ends of the body 2 in the axial direction, and a cylindrical inlet-side expanded diameter section 3 and an outlet-side expanded diameter section 4 interposed between the body 2 and each of the pipe sections 5, 6. Furthermore, the inlet-side expanded diameter section 3 is provided with an internal protrusion 7.

[0012] The pipe sections 5 and 6 have substantially the same specifications, and the expanded diameter sections 3 and 4 have substantially the same specifications if the expanded diameter section 3 does not have an internal protrusion 7. The dashed-dotted line CL in the drawing indicates the axis passing through the center of the cross section of the body section 2, the expanded diameter sections 3 and 4, and the pipe sections 5 and 6, and the extending direction of the dashed-dotted line CL is the cylindrical axis direction.

[0013] Each part constituting the silencer 1 is made of resin, and each part is basically formed of the same resin. The resin used is a variety of known thermoplastic resins, such as nylon resin (such as nylon 66), polypropylene, ABS resin, etc.

[0014] For reinforcement, short fibers (such as glass fibers or carbon fibers) can be mixed into the resin at a predetermined ratio (for example, 30% to 40% by mass per 100 parts by mass of the resin). The size of the short fibers is, for example, an outer diameter of about 0.001 mm to 1.0 mm and a length of about 0.01 mm to 10 mm.

[0015] Each of the pipe sections 5 and 6 is connected to the piping of an automobile air conditioner. Refrigerant R used in the air conditioner flows inside the silencer 1. The refrigerant R flows into the body section 2 through the inlet-side pipe section 5 and the inlet-side expanded diameter section 3, and flows out of the body section 2 through the outlet-side expanded diameter section 4 and the outlet-side pipe section 6.

[0016] The body 2 is a cylindrical body with a substantially constant peripheral wall thickness and a length L1. The peripheral wall thickness (inner diameter and outer diameter) and length L1 of the body 2 are not particularly limited and are determined appropriately depending on the performance required of the silencer 1. To cite an example of specific dimensions, the inner diameter of the body 2 is, for example, 30 mm to 60 mm, the peripheral wall thickness is 2 mm to 5 mm, and the length L1 is 20 mm to 200 mm.

[0017] The pipe sections 5, 6 are cylindrical bodies having a smaller diameter than the body section 2, and flow paths 5a, 6a are formed by their inner circumferential surfaces. The thickness (inner diameter and outer diameter) and length of the peripheral walls of the pipe sections 5, 6 are not particularly limited and are determined appropriately depending on the performance required of the silencer 1. The inner diameter of each of the pipe sections 5, 6 is, for example, 10 mm to 20 mm, and the thickness of the peripheral walls is approximately the same as that of the body section 2.

[0018] Each of the expanded diameter sections 3, 4 is formed in a cylindrical shape with an outer circumferential surface 3b, 4b expanding in diameter toward the body section 2, and has a length L2. Since there is a dimensional difference (outer diameter difference) between the outer circumferential surface of each of the pipe sections 5, 6 and the outer circumferential surface of the body section 2, the outer circumferential surfaces 3b, 4b of each of the expanded diameter sections 3, 4 are inclined cylindrical surfaces that smoothly connect the outer circumferential surfaces of each of the pipe sections 5, 6 and the outer circumferential surface of the body section 2 so as to smoothly change this dimensional difference.

[0019] In Figure 2, the boundary in the axial direction between the expanded diameter portion 3 and the pipe portion 5 and the boundary in the axial direction between the expanded diameter portion 3 and the body portion 2 are indicated by dashed lines, and these boundaries are smooth and continuous, with the portions on either side of the boundary being integrated. The bent portion of the outer peripheral surface 3b is formed in a moderate arc shape. This shape is also true for the boundary in the axial direction between the expanded diameter portion 4 and the pipe portion 6 and the boundary in the axial direction between the expanded diameter portion 4 and the body portion 2. The area X surrounded by the two-dot chain line in Figure 2 indicates the peripheral wall of the silencer 1 at the base of the internal protrusion 7.

[0020] The inclination angle a1 of each outer peripheral surface 3b, 4b with respect to the cylindrical axis direction of the pipe portions 5, 6 is preferably, for example, 30° to 60°. If the inclination angle a1 is less than 30°, the length L2 becomes too large, requiring a larger space to install the silencer 1 and is disadvantageous for weight reduction. If the inclination angle a1 exceeds 60°, when the internal pressure of the refrigerant R acts on the silencer 1, excessive stress is likely to occur locally near the boundaries between each pipe portion 5, 6 and each enlarged diameter portion 3, 4, and near the boundaries between each enlarged diameter portion 3, 4 and the body portion 2. Accordingly, to ensure sufficient pressure resistance, it becomes necessary to increase the thickness of the peripheral wall at each location, which is disadvantageous for weight reduction.

[0021] In this embodiment, the thickness of the peripheral walls 3a, 4a of the respective enlarged diameter portions 3, 4 is substantially constant. Therefore, the inner peripheral surfaces of the respective enlarged diameter portions 3, 4 expand in diameter along the respective outer peripheral surfaces 3b, 4b toward the body portion 2. The thickness of the peripheral walls 3a, 4a of the respective enlarged diameter portions 3, 4 is substantially the same (approximately equivalent) as the thickness of the peripheral walls of the body portion 2 and the respective pipe portions 5, 6.

[0022] The length L2 of each of the expanded diameter portions 3 and 4 is sufficiently small relative to the length L1 of the body portion 2, for example, the length L2 is 20% or less, or 10% or less of the length L1. This length L2 is set based on the outer diameter of the body portion 2, the outer diameters of the pipe portions 5 and 6, an appropriate inclination angle a1, etc.

[0023] The internal protrusion 7 provided in the expanded diameter section 3 has an internal flow path 8. This internal flow path 8 is continuous with the flow path 5a of the pipe section 5 connected to the expanded diameter section 3 and protrudes in the cylindrical axis direction of the pipe section 5 toward the trunk section 2. The cylindrical axis direction position of the protruding tip 7t of the internal protrusion 7 (i.e., the protruding tip of the internal flow path 8) is set near the cylindrical axis direction boundary M (hereinafter referred to as boundary M) between the expanded diameter section 3 and the trunk section 2. In this embodiment, the cylindrical axis direction position of the protruding tip 7t is set at the same position as boundary M, but it may be any position as long as it is near boundary M. The vicinity of boundary M means, for example, a range from a position protruding 20 mm in the cylindrical axis direction of the pipe section 5 toward the trunk section 2 to a position 10 mm back from boundary M (a range of +20 mm to -10 mm from boundary M). It is more preferable to set the cylindrical axis direction position of the protruding tip 7t at a position protruding toward the trunk section 2 beyond boundary M.

[0024] In this embodiment, the internal protrusion 7 is a cylindrical body protruding in the axial direction of the pipe section 5 at a position spaced inward from the maximum inner diameter position of the peripheral wall 3a of the expanded diameter section 3 connected to the body section 2. The inclination angle a2 of the outer peripheral surface of the internal protrusion 7 of the cylindrical body forming the internal flow path 8 relative to the inner peripheral surface (in the axial direction) is set to, for example, 30° or less, preferably 15° or less. This inclination angle a2 can also be set to zero, making the thickness of the peripheral wall of the internal protrusion 7 of the cylindrical body substantially constant in the axial direction. As in this embodiment, it is more preferable for the internal protrusion 7 to have a tapered shape in which the wall thickness (wall thickness) gradually decreases from the base to the tip. Adopting such a specification is advantageous for reducing the weight of the internal protrusion 7 while mitigating stress concentration at the base, compared to a specification in which the wall thickness (wall thickness) of the internal protrusion 7 is constant.

[0025] This inclination angle a2 can be set larger, but the larger the inclination angle a2, the greater the volume of the resin forming the internal protrusion 7, which is disadvantageous for weight reduction. Therefore, from the perspective of weight reduction, the inclination angle a2 is preferably between 0° and 15°, and more preferably 10° or less. The boundary portion between the outer peripheral surface of the internal protrusion 7 of the cylindrical body and the peripheral wall 3a of the expanded diameter portion 3 (i.e., the base portion of the internal protrusion 7 of the cylindrical body) is preferably made arc-shaped as in this embodiment in order to improve pressure resistance.

[0026] Furthermore, the thickness of the peripheral wall of the silencer 1 at the base of the internal protrusion 7 illustrated in FIG. 2 (thickness at the X portion) is preferably thicker than the thickness of the peripheral wall at other portions of the silencer 1. This configuration improves the strength of the base of the internal protrusion 7, which is advantageous for preventing cracks from occurring at this base. The thickness of the peripheral wall of the silencer 1 at the base of the internal protrusion 7 (thickness at the X portion) is defined as the length of a line segment drawn from a position corresponding to the base end of the internal flow path 8 of the internal protrusion 7 in the vertical cross-sectional view illustrated in FIG. 2, to the curved outer surface connecting the pipe portion 5 and the expanded diameter portion 3. At the end point, this line segment intersects perpendicularly with a tangent to the curved outer surface.

[0027] The embodiment of the silencer 1 illustrated in FIGS. 4 and 5 differs from the embodiment illustrated in FIGS. 1 to 3 in the specifications of the internal protrusion 7, but the other specifications are the same. This internal protrusion 7 has a protrusion tip 7t that forms a circular ring shape extending from the tip of the internal flow passage 8 to the inner circumferential surface 2a of the body 2. That is, the inclination angle a2 of the outer circumferential surface of the internal protrusion 7, which forms the internal flow passage 8, relative to the inner circumferential surface (in the cylindrical axis direction) is 90°, and the outer circumferential surface of the internal protrusion 7 is joined to the maximum inner diameter position of the peripheral wall 3a of the expanded diameter portion 3. Therefore, in this embodiment, the inclination angle a2 is much larger than in the previous embodiment. A larger inclination angle a2 is advantageous for improving the pressure resistance of the expanded diameter portion 3. While the inclination angle a2 can be set to exceed 90°, an excessively large angle is disadvantageous for weight reduction and reduces sound deadening performance, so it is set to be 100° or less.

[0028] The embodiment of the silencer 1 illustrated in Figs. 6 and 7 differs from the embodiment illustrated in Figs. 1 to 3 in the specifications of the internal protrusion 7, but the other specifications are the same. This internal protrusion 7 has a plurality of protrusions 7A that protrude in the axial direction of the pipe portion 5, spaced inward from the peripheral wall 3a of the expanded diameter portion 3 that is connected to the body portion 2. These plurality of protrusions 7A are arranged at intervals in the circumferential direction on the outer edge of the internal flow path 8. It is preferable that the protrusions 7A are arranged at equal intervals in the circumferential direction on the outer edge of the internal flow path 8, and the number of protrusions 7A is, for example, 3 to 8. As illustrated in Fig. 7, the protrusions 7A are arranged over a length range of 50% or more of the circular outer edge of the internal flow path 8 in a cross-sectional view.

[0029] In this embodiment, too, the inclination angle a2 of the outer peripheral surface of the internal protrusion 7 (protrusion 7A) forming the internal flow path 8 relative to the inner peripheral surface (cylinder axis direction) is set to 0° or more and 100° or less. From the viewpoint of weight reduction, as mentioned above, the inclination angle a2 is preferably 0° or more and 15° or less, and more preferably 10° or less. To significantly improve the pressure resistance of the expanded diameter portion 3, the inclination angle a2 is set to approximately 90°.

[0030] As in the embodiment of the silencer 1 illustrated in Fig. 8, the internal protrusion 7 may be provided not only in the inlet-side expanded diameter portion 3 but also in the outlet-side expanded diameter portion 4. In other words, it is sufficient that the internal protrusion 7 is provided at least in the inlet-side expanded diameter portion 3.

[0031] This silencer 1 may be manufactured using a known resin molding method (such as injection molding), and therefore a resin having specifications suited to the molding method to be used is selected and used.

[0032] This silencer 1 is installed in the engine compartment of an automobile, with the pipe sections 5 and 6 connected to the piping of an air conditioner. When the air conditioner is activated, refrigerant R flows into the body section 2 through the flow path 5a of the inlet pipe section 5 and the inlet-side expanded diameter section 3 (internal flow path 8), and flows out of the body section 2 through the outlet-side expanded diameter section 4 and the flow path 6a of the outlet-side pipe section 6. In this way, the refrigerant R circulates inside the silencer 1. Various known types of refrigerant R can be used, including hydrofluorocarbons (HFCs), hydrofluoroolefins (HFOs), hydrocarbons, carbon dioxide, and ammonia.

[0033] This silencer 1 is made entirely of resin, which is extremely advantageous in terms of weight reduction compared to metal silencers. However, simply using resin makes it difficult to improve pressure resistance. More specifically, when internal pressure acts on the silencer 1 due to the circulating refrigerant R, excessive stress occurs locally in the areas where the outer diameter changes suddenly between the body 2 and each of the pipe sections 5 and 6. As a result, the areas where excessive stress occurs locally become more susceptible to breakage.

[0034] Therefore, in this silencer 1, the body 2 and the respective smaller-diameter pipe sections 5, 6 are connected via cylindrical expanded-diameter sections 3, 4 whose outer circumferential surfaces 3b, 4b expand in diameter toward the body 2. Even when internal pressure acts on the silencer 1 due to the circulating refrigerant R, the respective expanded-diameter sections 3, 4 smoothly change the difference in outer diameter between the body 2 and the respective pipe sections 5, 6, thereby avoiding the occurrence of excessive stress locally, which is advantageous for ensuring sufficient pressure resistance. To ensure sufficient pressure resistance more reliably, it is advisable to set the inclination angle a1 of the outer circumferential surfaces 3b, 4b of the respective expanded-diameter sections 3, 4 with respect to the cylindrical axis direction of the pipe sections 5, 6 to be 60° or less.

[0035] The provision of the internal protrusion 7 on the inlet-side expanded diameter section 3 causes a sudden change (increase) in the cross-sectional area through which the refrigerant R flows at the protruding tip 7t of the internal flow path 8. As illustrated in FIG. 1 , the refrigerant R flows from the protruding tip 7t of the internal flow path 8 into the body 2, radially diffusing around the axial center CL of the body 2 and perpendicular to the axial center CL. The sudden change in the cross-sectional area of ​​the flowing refrigerant R is a major factor in improving noise reduction performance. It has been confirmed that the sudden change in the cross-sectional area of ​​the flowing refrigerant R, along with the generation of a radial flow perpendicular to the axial center CL of the body 2, improves noise reduction performance. Therefore, the use of the internal protrusion 7 provides excellent noise reduction performance. The silencer 1 effectively reduces noise and pulsation caused by the flowing refrigerant R.

[0036] Moreover, since the axial position of the protruding tip 7t of the internal protruding portion 7 is set near the boundary M between the expanded diameter portion 3 and the barrel portion 2, the length of the internal protruding portion 7 is limited. Therefore, an increase in weight due to the provision of the internal protruding portion 7 is suppressed. It has been found that a significant improvement in silencing performance can be obtained if the axial position of the protruding tip 7t is near the boundary M between the expanded diameter portion 3 and the barrel portion 2. Therefore, it is not necessary to extend the axial position of the protruding tip 7t to the center of the barrel portion 2. The axial position of the protruding tip 7t may be set to an appropriate position based on the results of prior silencing performance tests, simulations, etc.

[0037] 4 and 5 and the embodiment illustrated in FIGS. 6 and 7 also have the internal protrusion 7 on the inlet-side expanded diameter section 3, so the cross-sectional area through which the refrigerant R flows changes (increases) suddenly at the protrusion tip 7t of the internal flow path 8. This causes the refrigerant R to flow radially and diffuse perpendicular to the axial center CL of the body portion 2. Therefore, superior sound deadening performance can be obtained compared to when the internal protrusion 7 is not provided.

[0038] 1 to 3, the cross-sectional area through which the refrigerant R flows at the protruding tip 7t of the internal flow path 8 changes more rapidly than the internal protruding part 7 shown in Figures 6 and 7, making it easier to diffuse the refrigerant R radially in a direction perpendicular to the axial center CL of the body part 2, which is advantageous for improving sound deadening performance. Furthermore, the internal protruding part 7 of the cylindrical body shown in Figures 1 to 3 is advantageous for weight reduction compared to the internal protruding part 7 shown in Figures 4 and 5. The internal protruding part 7 of the cylindrical body shown in Figures 6 and 7 is advantageous for weight reduction compared to the internal protruding part 7 of the cylindrical body shown in Figures 1 to 3.

[0039] 8, when the internal protrusion 7 is provided not only in the inlet-side expanded diameter section 3 but also in the outlet-side expanded diameter section 4, the cross-sectional area through which the refrigerant R flows changes (decreases) abruptly at the protruding tip 7t of the internal protrusion 7. As a result, the refrigerant R flows perpendicular to the axial center CL of the body section 2, thereby improving the silencing performance compared to when the outlet-side expanded diameter section 4 does not have the internal protrusion 7.

[0040] In each of the above-described embodiments of the silencer 1, the axial center CL of the pipe portion 5 and the axial center CL of the pipe portion 6 extend coaxially, but the arrangement of the pipe portions 5, 6 is not limited to this. As in the embodiment of the silencer 1 illustrated in Fig. 9, the axial centers CL of the pipe portions 5, 6 may also intersect. In this embodiment, the axial center CL of the body portion 2 and the axial center CL of the pipe portion 6 extend coaxially, and the axial centers CL of the pipe portions 5, 6 intersect at an angle of 90°. The intersecting angle between the axial centers CL of the pipe portions 5, 6 is not limited to 90°, and may be an acute or obtuse angle.

[0041] 10, the silencer 1 may be designed so that the axial centers CL of the pipe portions 5, 6 are offset from each other in a direction perpendicular to the axial center CL of the body portion 2. The offset amount of the axial centers CL of the pipe portions 5, 6 is set appropriately depending on the requirements for the silencer 1, etc.

[0042] Since there are various restrictions on the installation space of the silencer 1, it is possible to install the silencer 1 under those restrictions by adopting specifications such as those of the embodiment illustrated in Figures 9 and 10. In other words, the intersecting angle and offset amount between the axial centers CL of the pipe sections 5, 6 can be appropriately set according to the restrictions on the installation space of the silencer 1, as illustrated in Figures 9 and 10.

[0043] The effects described in each of the above-mentioned embodiments can also be obtained with the embodiment shown in Figures 9 and 10. In the embodiment shown in Figure 9, the cross-sectional area through which the refrigerant R flows suddenly changes (increases) at the protruding tip 7t of the internal flow path 8. This causes the refrigerant R to flow radially and diffuse parallel to the axial center CL of the body portion 2, thereby achieving superior sound deadening performance compared to when the internal protruding portion 7 is not provided. The various specifications described in each of the above-mentioned embodiments can also be applied to the embodiment shown in Figures 9 and 10.

[0044] The present disclosure encompasses the following inventions: Invention 1: A resin silencer having a cylindrical body portion, pipe portions each having a diameter smaller than that of the body portion and disposed at both ends of the body portion in a cylindrical axis direction, and cylindrical expanded diameter portions connected between each of the pipe portions and the body portion and having an outer circumferential surface that expands in diameter toward the body portion, wherein each of the pipe portions is connected to a piping of an automotive air conditioner, At least one of the enlarged diameter sections is provided with an internal protruding section having an internal flow path that is continuous with the flow path of the connected pipe section and protrudes in the axial direction of the pipe section toward the body section, and the axial position of the protruding tip of the internal protruding section is set near the axial boundary between the enlarged diameter section and the body section, and a resin silencer is formed in which refrigerant flows into the body section through the internal flow path. Invention 2: A resin silencer as described in Invention 1, wherein the internal protrusion is a cylindrical body protruding in the axial direction of the cylinder at a position spaced inward from the maximum inner diameter position of the peripheral wall of the expanded diameter portion connected to the body portion. Invention 3: The resin silencer described in Invention 1, wherein the internal protrusion has a plurality of protrusions that protrude in the axial direction of the cylinder at a distance from the peripheral wall of the expanded diameter section that is connected to the body section, and the plurality of protrusions are arranged at intervals in the circumferential direction on the outer edge of the internal flow path. Invention 4: 4. A resin silencer according to any one of inventions 1 to 3, wherein the internal protrusion has a tapered shape in which the thickness thereof gradually decreases from the base portion to the tip portion. Invention 5: The resin silencer according to invention 1, wherein the protruding tip of the internal protruding portion is an annular surface that extends from the tip of the internal flow path toward the outer periphery to the inner circumferential surface of the body portion. Invention 6: 6. The resin silencer according to any one of inventions 1 to 5, wherein each of the enlarged diameter portions has the internal protrusion. Invention 7: A resin silencer according to any one of inventions 1 to 6, wherein the thickness of the peripheral wall of the silencer at the base of the internal protrusion is thicker than the thickness of the peripheral wall in other parts of the silencer. [Explanation of symbols]

[0045] 1 silencer 2. Torso 2a Inner surface 3 Enlarged diameter part on inlet side 3a Peripheral wall 3b Outer surface 4 Expanded diameter part on exit side 4a Peripheral wall 4b Outer surface 5 Inlet pipe section 5a Flow path 6 Outlet pipe section 6a Flow path 7 Internal protrusion 7A protrusion 7t protruding tip 8 Internal flow path R refrigerant

Claims

1. A resin silencer having a cylindrical body portion, pipe portions each having a diameter smaller than that of the body portion and disposed at both ends of the body portion in a cylindrical axis direction, and cylindrical expanded diameter portions connected between each of the pipe portions and the body portion and having an outer circumferential surface that expands in diameter toward the body portion, wherein each of the pipe portions is connected to a piping of an automotive air conditioner, At least one of the enlarged diameter sections is provided with an internal protruding section having an internal flow path that is continuous with the flow path of the connected pipe section and protrudes in the axial direction of the pipe section toward the body section, and the axial position of the protruding tip of the internal protruding section is set near the axial boundary between the enlarged diameter section and the body section, and a resin silencer is formed in which refrigerant flows into the body section through the internal flow path.

2. 2. A resin silencer as described in claim 1, wherein the internal protrusion is a cylindrical body protruding in the axial direction of the cylinder at a position spaced inward from the maximum inner diameter position of the peripheral wall of the expanded diameter portion connected to the body portion.

3. A resin silencer as described in claim 1, wherein the internal protrusion has a plurality of protrusions that protrude in the axial direction of the cylinder, spaced apart from the inner peripheral wall of the expanded diameter portion that is connected to the body portion, and the plurality of protrusions are arranged at intervals in the circumferential direction on the outer edge of the internal flow path.

4. 4. The resin silencer according to claim 1, wherein the internal protrusion has a tapered shape in which the thickness thereof gradually decreases from the base to the tip.

5. 2. The resin silencer according to claim 1, wherein the protruding tip of the internal protruding portion is an annular surface that extends from the tip of the internal flow passage toward the outer periphery to the inner circumferential surface of the body portion.

6. 2. The resin silencer according to claim 1, wherein each of said enlarged diameter portions has said internal protrusion.

7. 2. The resin silencer according to claim 1, wherein the thickness of the peripheral wall of the silencer at the base of the internal protrusion is greater than the thickness of the peripheral wall at other portions of the silencer.

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