Resin silencer

Abstract

The present invention provides a resin silencer to be connected to the piping of an automotive air conditioner, the silencer having excellent silencing performance along with sufficient ability to withstand pressure while being lightweight. A cylindrical body part 2 and smaller-diameter pipe parts 5, 6 arranged at both end parts in the cylinder-axial direction of the body part 2 are connected to each other via cylindrical diameter expansion parts 3, 4 having outer peripheral surfaces 3b, 4b that expand in diameter proceeding toward the body part 2. At least the diameter expansion part 3 on one end is provided with an internal projection part 7 having an internal flow passage 8 projecting in the cylinder-axial direction of the pipe part 5 toward the body part 2 in a manner continuous with a flow passage 5a of the connected pipe part 5. The cylinder-axial position of a projection tip 7t of the internal projection part 7 is set in the vicinity of a cylinder-axial direction boundary between the diameter expansion part 3 and the body part 2. A refrigerant R is made to flow into the body part 2 through the flow passage 5a and an internal flow passage 8 of the pipe part 5 on one end, and this refrigerant R is made to flow out from the body part 2 through a flow passage 6a of the pipe part 6 on the other end.

Description

Resin silencer

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

[0002] A silencer is connected to the piping of an automotive 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 in 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).

[0004] Japanese Patent Publication No. 2000-205701 Japanese Patent Publication No. 2011-12869

[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 large-diameter cylindrical portion of the 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.

[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.

[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.

[0009] FIG. 1 is an explanatory diagram illustrating an embodiment of a silencer in a vertical cross-sectional view. FIG. 2 is a partially enlarged view of FIG. 1. FIG. 3 is a cross-sectional view taken along the line A-A in FIG. 2. FIG. 4 is an explanatory diagram illustrating a partially enlarged cross-sectional view of another embodiment of a silencer. FIG. 5 is a cross-sectional view taken along the line B-B in FIG. 4. FIG. 6 is an explanatory diagram illustrating a partially enlarged cross-sectional view of another embodiment of a silencer. FIG. 7 is a cross-sectional view taken along the line C-C in FIG. 6. FIG. 8 is an explanatory diagram illustrating a further embodiment of a silencer in a vertical cross-sectional view. FIG. 9 is an explanatory diagram illustrating a further embodiment of a silencer in which the pipe sections are arranged differently. FIG. 10 is an explanatory diagram illustrating a further embodiment of a silencer in which the pipe sections are arranged differently in a vertical cross-sectional view.

[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 has an internal protrusion 7.

[0012] The pipe sections 5 and 6 have substantially the same specifications, and the enlarged diameter sections 3 and 4 have substantially the same specifications if the enlarged 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 enlarged 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 of the silencer 1 is made of resin, and each part is basically made of the same resin. The resin used is a variety of known thermoplastic resins, such as nylon resin (such as nylon 66), polypropylene, and ABS resin.

[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 pipes 5 and 6 is connected to the piping of an automotive air conditioner. A refrigerant R used in the air conditioner flows inside the silencer 1. The refrigerant R flows into the body 2 through the inlet pipe 5 and the inlet enlarged diameter section 3, and flows out of the body 2 through the outlet enlarged diameter section 4 and the outlet pipe 6.

[0016] The body 2 is a cylindrical body having 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 portions 5, 6 are cylindrical bodies having a smaller diameter than the body portion 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 portions 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 portions 5, 6 is, for example, 10 mm or more and 20 mm or less, and the thickness of the peripheral walls is approximately the same as that of the body portion 2.

[0018] Each of the expanded diameter sections 3, 4 is formed in a cylindrical shape with a length L2, with outer peripheral surfaces 3b, 4b expanding in diameter toward the body section 2. Since there is a dimensional difference (outer diameter difference) between the outer peripheral surfaces of the respective pipe sections 5, 6 and the outer peripheral surface of the body section 2, the outer peripheral surfaces 3b, 4b of each of the expanded diameter sections 3, 4 are inclined cylindrical surfaces that smoothly connect the outer peripheral surfaces of the respective pipe sections 5, 6 and the outer peripheral 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 3 a, 4 a 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 3 b, 4 b toward the body portion 2. The thickness of the peripheral walls 3 a, 4 a 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 compared 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 axial direction of the pipe section 5 toward the barrel section 2. The axial 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 axial boundary M (hereinafter referred to as boundary M) between the expanded diameter section 3 and the barrel section 2. In this embodiment, the axial position of the protruding tip 7t is set at the same position as boundary M, but it may be set near boundary M. The vicinity of boundary M refers to, for example, a range from a position protruding 20 mm in the axial direction of the pipe section 5 toward the barrel 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 axial position of the protruding tip 7t at a position protruding toward the barrel 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 barrel section 2. The inclination angle a2 of the outer peripheral surface of the internal protrusion 7 of the cylindrical body forming the internal flow passage 8 relative to the inner peripheral surface (in the axial direction) is set to, for example, 30° or less, preferably 15° or less. The 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 (peripheral wall thickness) gradually decreases from its base to its tip. Adopting such a design is advantageous for reducing stress concentration at the base while suppressing weight increase of the internal protrusion 7 compared to a design in which the wall thickness (peripheral 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 0° or more and 15° or less, and more preferably 10° or less. The boundary portion between the outer circumferential 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 a 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. The internal protrusion 7 has a protrusion tip 7t that forms a circular ring-shaped surface 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 100° or less.

[0028] The embodiment of the silencer 1 illustrated in Figures 6 and 7 is the same as the embodiment illustrated in Figures 1 to 3 except for the specifications of the internal protrusion 7. 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 Figure 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 (projection 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 described 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. That is, it is sufficient that the internal protrusion 7 is provided at least in the inlet-side expanded diameter portion 3.

[0031] The silencer 1 may be manufactured using a known resin molding method (such as injection molding), and 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, 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-side 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] Because the silencer 1 is entirely made of resin, it 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 is generated locally in the portions where the outer diameter changes suddenly between the body portion 2 and each of the pipe portions 5 and 6. As a result, the portions where excessive stress is generated locally become prone 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, which is advantageous for preventing excessive stress from occurring locally and ensuring sufficient pressure resistance. To more reliably ensure sufficient pressure resistance, 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 about 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 sound deadening performance. It has been confirmed that the sudden change in the cross-sectional area of ​​the flowing refrigerant R, accompanied by the generation of a radial flow perpendicular to the axial center CL of the body 2, improves sound deadening performance. Therefore, the use of the internal protrusion 7 provides excellent sound deadening performance. The silencer 1 effectively reduces noise and pulsation caused by the flowing refrigerant R.

[0036] Moreover, since the position in the cylinder axis direction 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 considerable improvement in silencing performance can be obtained if the position in the cylinder axis direction 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 position in the cylinder axis direction of the protruding tip 7t to the center of the barrel portion 2 in the cylinder axis direction. The position in the cylinder axis direction 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 embodiments illustrated in FIGS. 6 and 7 also include the internal protrusion 7 in 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 radially diffuse the refrigerant R perpendicular to the axial center CL of the body portion 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 reducing weight 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 reducing weight 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 crossing 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 embodiments illustrated in Figures 9 and 10 can also achieve the effects described in the above-mentioned embodiments. In the embodiment illustrated 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 creates a flow in which the refrigerant R diffuses radially parallel to the axial center CL of the body portion 2, thereby achieving superior sound deadening performance compared to a case in which the internal protruding portion 7 is not provided. The various specifications described in the above-mentioned embodiments can also be applied to the embodiments illustrated in Figures 9 and 10.

[0044] 1 Silencer 2 Body 2a Inner circumferential surface 3 Enlarged diameter part on the inlet side 3a Peripheral wall 3b Outer circumferential surface 4 Enlarged diameter part on the outlet side 4a Peripheral wall 4b Outer circumferential surface 5 Inlet side pipe section 5a Flow path 6 Outlet side pipe section 6a Flow path 7 Internal protrusion 7a Projection 7t Projection tip 8 Internal flow path R Refrigerant

Claims

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

2. A resin silencer as described in claim 1, wherein the internal protrusion is a cylindrical body that protrudes 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 section connected to the body section.

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 at a distance inward 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.

4. A resin silencer according to any one of claims 1 to 3, wherein the internal protrusion has a tapered shape in which the thickness gradually decreases from the base to the tip.

5. A resin silencer as set forth in claim 1, wherein the protruding tip of the internal protrusion is an annular surface extending from the tip of the internal flow passage to the outer periphery of the body.

6. A resin silencer according to any one of claims 1 to 5, wherein each of said enlarged diameter portions has said internal protrusion.

7. A resin silencer as set forth in any one of claims 1 to 6, 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 in other parts of the silencer.

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