Method for manufacturing resin silencer

Abstract

The present invention provides a method whereby a resin silencer can be manufactured by a simpler operation by uniting two divided resin bodies by a simpler operation. Provided is a silencer 1 in which a small-diameter pipe part 4 is connected to both axial end parts of a cylindrical body part 2 via a pipe expansion part 3. The silencer is formed through resin molding of divided bodies 6, 8 having a shape divided into two parts across an axial direction. An opposing part 7 of one divided body 6 is formed so as fit into an opposing part 9 of the other divided body 8. Threaded parts 7a, 9a to be threaded together are formed in the opposing parts 7, 9, respectively. The threaded parts 7a, 9a are threaded together with a seal material 10 interposed, thus fastening and uniting the divided bodies 6, 8 with each other.

Description

Manufacturing method for resin silencer

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

[0002] Silencers are attached to the piping of automotive air conditioners to suppress noise caused by the flow of circulating refrigerant. In recent years, with the trend toward lighter automobiles, various studies have been conducted on replacing metal piping with plastic piping to reduce weight.

[0003] In order to manufacture a resin silencer that is lightweight yet has sufficient resistance to internal pressure, a method has been proposed in which a cylindrical insertion part (insertion part) and a cylindrical receiving part (receiving part) are integrated into a cylindrical part by spin welding (see Patent Document 1). In this proposed method, the specifications of the insertion part and the receiving part are devised to enable a stable and strong joining of the two.

[0004] However, this manufacturing method requires a spin welding machine to integrate the inserting part and the receiving part, and also requires work such as setting each part precisely in the welding machine before welding. Therefore, there is room for improvement in order to integrate two resin parts with a simpler process.

[0005] Japanese Patent Application Publication No. 2023-155659

[0006] An object of the present invention is to provide a manufacturing method that can more simply manufacture a resin silencer to be connected to the piping of an automotive air conditioner by integrating two resin split bodies.

[0007] In order to achieve the above object, the manufacturing method of a resin silencer of the present invention is a manufacturing method of a resin silencer to be connected to the piping of an automotive air conditioner, the silencer having a cylindrical body and pipe sections connected to both axial ends of the body via expanded sections and having a smaller diameter than the body, characterized in that the silencer is formed by molding a split body shaped to be divided into two across the axial direction by resin molding, the opposing section of one of the split bodies being fitted into the opposing section of the other split body, and threaded sections that thread together are formed on the opposing sections of each of the split bodies, and the threaded sections are threaded together and sealed with a sealing material between them to fasten the split bodies together.

[0008] According to the present invention, the opposing portions of each of the divided bodies are formed with threaded portions that thread together, and the divided bodies can be integrated by fastening the divided bodies together with the threaded portions threaded together and a sealing material interposed therebetween. Furthermore, because a sealing material is interposed between the opposing portions, this manufacturing method makes it possible to manufacture a lightweight resin silencer that is sufficiently pressure-resistant to internal pressure with a simpler process.

[0009] FIG. 1 is an explanatory diagram illustrating a silencer manufactured according to the present invention, as seen from the front. FIG. 2 is an explanatory diagram illustrating the silencer of FIG. 1, as seen from the longitudinal cross section. FIG. 3 is an explanatory diagram illustrating one divided body and the other divided body of FIG. 2, separated from each other. FIG. 4 is an explanatory diagram illustrating the internal structure of one divided body, as seen from the opposing portion. FIG. 5 is an explanatory diagram illustrating the internal structure of the other divided body, as seen from the opposing portion. FIG. 6 is an explanatory diagram illustrating a state in which band bodies are fitted over the divided bodies so as to cover the opposing portions of FIG. 2. FIG. 7 is an explanatory diagram illustrating a modified reinforcing rib, as seen from the front of the silencer. FIG. 8 is an explanatory diagram illustrating another modified reinforcing rib, as seen from the front of the silencer.

[0010] Hereinafter, a method for manufacturing a resin silencer according to the present invention will be described based on an embodiment shown in the drawings.

[0011] According to the present invention, a resin silencer 1 as shown in Figures 1 and 2 is manufactured. This silencer 1 has a cylindrical body 2, and pipe sections 4 each having a smaller diameter than the body 2 are connected to both axial ends of the body 2 via expanded sections 3. Each pipe section 4 is connected to the piping of an automotive air conditioner. A refrigerant C used in the air conditioner circulates and flows inside the hollow silencer 1. The refrigerant C flows in from one pipe section 4 and out from the other pipe section 4. The dashed-dotted line CL in the figures indicates the axis of the silencer 1, which passes through the center of the cross section of the body 2, expanded section 3, and pipe section 4. The direction in which the axis center CL extends is the axial direction.

[0012] The silencer 1 is manufactured by joining together two resin divided bodies 6 and 8, as shown in Figures 3 to 5. Each divided body 6 and 8 is basically made of the same resin. This resin may be any of a variety of known moldable resins. Examples include nylon resin (such as 66 nylon), polypropylene, and ABS resin.

[0013] 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.

[0014] Each of the divided bodies 6, 8 has a shape in which the silencer 1 is divided into two parts transverse to the axial direction, and is manufactured by resin molding. In this embodiment, each of the divided bodies 6, 8 has a shape in which the silencer 1 is divided into two parts along a direction perpendicular to the axial direction (at an angle of 90°).

[0015] The inner diameter of the body portion 2 is, for example, about 30 mm to 60 mm. The inner diameter of the pipe portion 4 is, for example, about 10 mm to 20 mm. The thickness of the peripheral walls of the body portion 2, the expanded tube portion 3, and the pipe portion 4 is approximately the same, for example, about 2 mm to 5 mm.

[0016] The opposing portions 7, 9 of the body portion 2 of each of the segments 6, 8 are fitted together, and the two segments 6, 8 are fastened together and integrated. In this embodiment, the inner diameter of each opposing portion 7, 9 is the same as the inner diameter of the surrounding body portion 2 (the inner diameter of the portion where the circumferential rib 5b described later does not exist), but the outer diameter is larger than the outer diameter of the surrounding body portion 2 (the outer diameter of the portion where the circumferential rib 5a described later does not exist), and protrudes outward. Therefore, the fastening portions of the segments 6, 8 (the portions corresponding to the opposing portions 7, 9) function as circumferential ribs.

[0017] One opposing portion 7 is a convex annular body having a threaded portion 7a, while the other opposing portion 9 is a concave annular body having a threaded portion 9a, with the convex opposing portion 7 fitted into the concave opposing portion 9. The threaded portion 7a on the outer circumferential surface of the opposing portion 7 and the threaded portion 9a on the inner circumferential surface of the opposing portion 9 are screwed together, fastening the divided bodies 6, 8 together and integrating them. An annular seal material 10 is fitted into an annular seal groove formed in the opposing surface of the opposing portion 9a that faces the tip surface of the opposing portion 7. Various known types of seal material 10, such as an O-ring made of silicone rubber, can be used as the seal material.

[0018] The sealing material 10 can be attached not only in one place but also in multiple places. For example, as the sealing material 10, a known waterproof sealing material in the form of a tape can be interposed between the threaded portions 7a and 9a.

[0019] The expanded tube portion 3 is a cylindrical body whose diameter expands from the cylindrical pipe portion 4 toward the cylindrical body portion 2. The expanded tube portion 3 is a cylindrical body that changes from the small diameter pipe portion 4 to the shape of the large diameter body portion 2.

[0020] The inclination angle of the peripheral wall of the expanded tube section 3 relative to the axis CL is, for example, approximately 30° to 60°. The boundary between the expanded tube section 3 and the body section 2 is convex arc-shaped, and the arc radius (R1 dimension) of the outer surface of this boundary is, for example, approximately 10 mm to 20 mm. The arc radius (R2 dimension) of the inner surface of this boundary is set so that the thickness (thickness between the outer and inner surfaces) is constant. The boundary between the expanded tube section 3 and the pipe section 4 is concave arc-shaped, and the arc radius (R3 dimension) of the outer surface of this boundary is, for example, approximately 10 mm to 20 mm. The arc radius (R4 dimension) of the inner surface of this boundary is set so that the thickness (thickness between the outer and inner surfaces) is constant. Therefore, the cylindrical body section 2 and the cylindrical pipe section 4 are smoothly connected by the expanded tube section 3, whose inner and outer diameters gradually change.

[0021] Circumferential ribs 5a are provided on the outer peripheral surface of the barrel 2 so as to reinforce the barrel 2. In this embodiment, the plurality of circumferential ribs 5a are arranged at intervals in the axial direction. The circumferential ribs 5a may be arranged at equal intervals in the axial direction. The circumferential ribs 5a are arranged at least in the axial center of the barrel 2.

[0022] The protruding height of the circumferential ribs 5 a (the amount of protrusion radially outward from the outer circumferential surface of the body 2) is, for example, about 2 mm to 5 mm, and the rib width is, for example, about 1 mm to 5 mm. The number and dimensions of the circumferential ribs 5 a are determined appropriately based on the pressure resistance required of the silencer 1, etc.

[0023] In this embodiment, a circumferential rib 5b is provided on the inner peripheral surface of the body 2 so as to extend continuously in the circumferential direction. The circumferential rib 5b is primarily intended to improve the sound deadening effect, but also has the effect of reinforcing the body 2. In this embodiment, a plurality of circumferential ribs 5b are arranged at intervals in the axial direction. It is preferable that the circumferential ribs 5b are arranged at equal intervals in the axial direction. The circumferential ribs 5b can be provided as desired.

[0024] The protruding height of the circumferential ribs 5b (the amount of protrusion radially inward from the inner peripheral surface of the body 2) is, for example, about 2 mm to 5 mm, and the rib width is, for example, about 1 mm to 5 mm. The number and dimensions of the circumferential ribs 5b are determined appropriately based on the sound-deadening properties required of the silencer 1, etc.

[0025] The cross-sectional shape of the circumferential ribs 5 a, 5 b is not limited to a semicircular shape or other shape with an arc-shaped top, but may be a triangular shape, a square shape, or other polygonal shape, etc. Having an arc-shaped top is advantageous in improving the durability of the circumferential ribs 5 a, 5 b.

[0026] As in this embodiment, the circumferential ribs 5a and 5b are preferably arranged to be offset in the axial direction. That is, the circumferential ribs 5a and 5b should be arranged so as not to overlap in the axial direction. If the circumferential ribs 5a and 5b were arranged so as to overlap in the axial direction, the amount of resin in the body portion 2 would be excessively unevenly distributed, which would be disadvantageous for successful injection molding of the segments 6 and 8.

[0027] An example of a procedure for manufacturing the silencer 1 will now be described.

[0028] First, the segments 6 and 8 shown in Figures 3 to 5 are manufactured by a known resin molding method. For example, the segments 6 and 8 may be injection molded using a known injection molding machine. When the segments 6 and 8 are injection molded, the circumferential ribs 5a and 5b are also molded integrally at the same time. The threaded portion 7a is also molded integrally with the segment 6, and the threaded portion 9a and the seal groove into which the seal material 10 is attached are also molded integrally with the segment 8.

[0029] Next, a seal material 10 is fitted into the seal groove of the opposing portion 9. Then, as shown in Fig. 3, the opposing portions 7, 9 are opposed to each other. Next, the threaded portions 7a, 9a are screwed together, and the respective divided bodies 6, 8 are fastened together and integrated with the seal material 10 interposed therebetween, thereby manufacturing the silencer 1. When the threaded portions 7a, 9a are screwed together, the tip surface of one of the opposing portions 7 crushes the seal material 10, ensuring watertightness between the respective opposing portions 7, 9 (divided bodies 6, 8).

[0030] To fasten the threaded portions 7a, 9a together, the segments 6, 8 are rotated in opposite directions relative to each other about the axis CL. This fastening operation can be performed manually or by machine. Because the threaded portions 7a, 9a that thread together are formed on the opposing portions 7, 9, this fastening operation can be performed simply by threading the threaded portions 7a, 9a together. Furthermore, because the sealing material 10 is interposed between the opposing portions 7, 9, this manufacturing method allows for the manufacture of a lightweight resin silencer 1 that is sufficiently pressure-resistant to internal pressure with simpler operations.

[0031] In this silencer 1, the body portion 2 and the pipe portion 4 are connected via the expanded portion 3, so that when internal pressure acts during use of the silencer 1, it is possible to prevent excessive stress from occurring locally in the region between the body portion 2 and the pipe portion 4. The circumferential rib 5a resists the internal pressure acting on the silencer 1, so it is possible to prevent excessive stress from occurring locally. Therefore, with this silencer 1, it is possible to ensure sufficient pressure resistance against internal pressure even though it is made of lightweight resin.

[0032] 2, in the piping system of an automotive air conditioner, refrigerant C flows in through one pipe section 4, passes through the expanded pipe section 3, the body section 2, and the expanded pipe section 3, and flows out of the other pipe section 4, repeatedly circulating. In the expanded pipe section 3, the refrigerant C flows along the inner circumferential surface. In this embodiment, the circumferential rib 5b protruding from the inner circumferential surface of the body section 2 interferes with the flowing refrigerant C, thereby canceling out the noise and pulsation caused by the flowing refrigerant C, thereby further reducing the noise and pulsation.

[0033] The circumferential ribs 5b may be arranged in the axial direction with different protruding heights. The circumferential ribs 5b are not limited to the protruding direction perpendicular to the axial direction as in the above-described embodiment, but may be protruding at an angle toward the other axial side (the other pipe portion 4 side from which the refrigerant C flows out).

[0034] As shown in FIG. 6, a band body 11 can also be attached to the silencer 1 shown in FIG. 2. Specifically, the band body 11 is fitted onto each of the segments 6 and 8 so as to cover the opposing portions 7 and 9. This causes the band body 11 to apply a tightening force to the opposing portions 7 and 9. The tightening force applied by the band body 11 causes the opposing portion 9, located on the outer periphery of the opposing portion 7, to press the outer circumferential surface of the opposing portion 7 toward the axis CL. This causes the threaded portions 7a and 9a to adhere more tightly to each other, more firmly fastening the opposing portions 7 and 9 (segments 6 and 8) together and preventing loosening of the threads. This is even more advantageous in ensuring the pressure resistance of the silencer 1.

[0035] The band body 11 may be simply attached to the outer peripheral surface of the opposing part 9 of the silencer 1 in Fig. 2, but it is preferable to form an annular recess in which the band body 11 fits on the outer peripheral surface of the opposing part 9, as shown in Fig. 6. This prevents the band body 11 from shifting in the axial direction, which is advantageous for applying a stable tightening force with the band body 11.

[0036] The band body 11 may be of various known specifications that have a resin or metal belt and fastener and can be fixed to any desired loop length. For example, a band body 11 having a fastener with a ratchet mechanism may be used.

[0037] Ordinary resin silencers are not designed to be disassembled, but this silencer 1 can be disassembled by separating the segments 6 and 8 by unscrewing the threaded portions 7a and 9a. This allows for internal inspection of the silencer 1. Furthermore, rather than simply replacing a defective silencer 1 with a new one, it is also possible to continue using the silencer by replacing one of the segments 6 and 8.

[0038] In the silencer 1 described above, the threaded portions 7a, 9a of each of the segments 6, 8 are formed at the same time as the segments 6, 8 are molded, but this is not limiting. The threaded portions 7a, 9a may be formed in a subsequent process after the segments 6, 8 are molded. That is, the segments 6, 8 are molded without the threaded portions 7a, 9a of FIG. 3 being formed. Thereafter, the threaded portions 7a, 9a are formed on the opposing portions 7, 9 at an appropriate timing before the process of fastening the segments 6, 8 together is performed. The threaded portions 7a, 9a can be easily formed by known machining.

[0039] 7, in addition to the circumferential ribs 5a, axial ribs 5c extending in the axial direction may be provided on the outer peripheral surface of the body portion 2. The axial ribs 5c are molded integrally with the divided bodies 6 and 8 at the same time when the divided bodies 6 and 8 are injection molded.

[0040] The axial ribs 5c are preferably arranged at least in the axial center of the body portion 2, in the range where the circumferential ribs 5a are arranged. The protruding height and rib width of the axial ribs 5c are the same as those of the circumferential ribs 5a. Three or more axial ribs 5c are arranged at equal intervals around the circumferential direction of the body portion 2, and preferably, for example, three to twelve axial ribs. The specification including the axial ribs 5c in addition to the circumferential ribs 5a is advantageous in further improving the durability of the body portion 2 (silencer 1).

[0041] Instead of the axial ribs 5c shown in Fig. 7, as shown in Fig. 8, diagonal ribs 5d may be provided on the outer peripheral surface of the body 2, extending at an angle of, for example, 30° to 60° relative to the axial direction. The diagonal ribs 5d are molded integrally with the segments 6 and 8 simultaneously when they are injection molded. The protruding height and width of the diagonal ribs 5d are set to be the same as those of the circumferential ribs 5a.

[0042] In the above-described embodiment, the segments 6, 8 are fastened together by threading the threaded portions 7a, 9a. However, instead of or in addition to the threaded portions 7a, 9a, bolts can be used to fasten the segments 6, 8 together and integrate them. Specifically, bolts are inserted into the opposing portions 7, 9 that protrude from the outer periphery of the trunk portion 2. That is, bolt holes are formed in the opposing portions 7, 9. These bolt holes are provided at multiple locations circumferentially spaced apart (e.g., two to four equally spaced locations). Then, bolts are inserted into the opposing bolt holes of the opposing portions 7, 9 and threaded into the bolt holes, or nuts are threaded onto bolts inserted through the bolt holes to connect the opposing portions 7, 9 together. In this manner, the segments 6, 8 can be fastened together and integrated using bolts.

[0043] REFERENCE SIGNS LIST 1 silencer 2 body portion 3 expanded tube portion 4 pipe portion 5a, 5b circumferential rib 5c axial rib 5d diagonal rib 6 one divided body 7 opposing portion 7a threaded portion 8 other divided body 9 opposing portion 9a threaded portion 10 sealing material 11 band body C refrigerant

Claims

1. A method for manufacturing a resin silencer to be connected to the piping of an automotive air conditioner, the silencer having a cylindrical body and pipe sections connected to both axial ends of the body via expanded sections and having a smaller diameter than the body, wherein the silencer is formed by molding a split body shaped to be divided into two across the axial direction using resin, with the opposing section of one split body fitted inside the opposing section of the other split body, and threaded sections that screw together are formed on the opposing sections of each split body, and the threaded sections are screwed together and a sealant is placed between them to fasten the split bodies together.

2. A method for manufacturing a resin silencer as set forth in claim 1, wherein a band body is fitted onto each of the divided bodies so as to cover each of the opposing portions, and a clamping force is applied to each of the opposing portions by the band body.

3. A method for manufacturing a resin silencer according to claim 1 or 2, wherein the threaded portions of each of the divided bodies are formed at the same time as the divided bodies are molded.

4. A method for manufacturing a resin silencer according to claim 1 or 2, wherein the threaded portions of each of the divided bodies are formed in a subsequent process after each of the divided bodies has been molded.

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