Bellows air damper

Abstract

To provide a cornice air damper having all of liquid resistance, gas barrier properties and flex resistance.SOLUTION: A cornice air damper (100) has axially-continuous crest and valley parts. An inner layer (9), a first adhesion layer (10), an intermediate layer (11), a second adhesion layer (12) and an outer layer (13) are provided outward from an inside. The inner layer (9) and the intermediate layer (11) are made of an ethylene-vinyl alcohol copolymer (EVOH). The outer layer (13) is made of a fluororesin.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a bellows air damper for use in a fuel supply system of an automobile, etc. [Background technology]

[0002] Patent Document 1 describes a bellows used in an automobile fuel supply system. This bellows is used to suppress fuel pulsation. According to Patent Document 1, the material for the bellows is, for example, polyamide 12 resin (paragraph 0017 of Patent Document 1). Paragraph 0017 also describes that, in addition to polyamide 12 resin, a material selected from the group consisting of thermoplastic polyamide resin, thermoplastic polyolefin resin, thermoplastic fluororesin, thermoplastic polyester resin, thermoplastic polysulfide resin, thermoplastic elastomer, fluororubber, nitrile rubber, and acrylic rubber can be used as the material for the bellows. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5056838 Summary of the Invention [Problem to be solved by the invention]

[0004] As described above, various resin and rubber materials have been proposed as materials for bellows used in automotive fuel supply systems. However, the applicant's investigations revealed that no material existed that satisfied all of the performance requirements for bellows used in fuel supply systems to suppress fuel pulsation: (1) resistance to fuels such as gasoline, (2) gas barrier properties, and (3) flexural durability. Gas barrier properties refer to the resistance to gases enclosed within the bellows from escaping from within the bellows.

[0005] For example, bellows made of a single layer of polyethylene (PE), polyamide 12 (PA12), and fluororesin are resistant to fuel but have poor gas barrier properties. On the other hand, bellows made of a single layer of ethylene-vinyl alcohol copolymer (EVOH) have excellent gas barrier properties but are hard and brittle, resulting in poor flexural durability. Thus, single-layer bellows, i.e., bellows made of a single material, are not suitable for use in automotive fuel supply systems.

[0006] Therefore, the present applicant investigated a three-layer bellows structure composed of multiple layers of different materials, rather than a single-layer structure. The inner layer, which comes into contact with the gas inside the bellows, was made of ethylene-vinyl alcohol copolymer (EVOH), which has excellent gas barrier properties, and the outer layer, which comes into contact with the fuel, was made of fluororesin, which has excellent liquid resistance. The inner and outer layers were then bonded together with an adhesive layer (a resin material with adhesive properties) to prevent peeling between the layers. However, while this three-layer bellows was satisfactory in terms of liquid resistance and gas barrier properties, it was not satisfactory in terms of flexural durability (as will be described in more detail below).

[0007] An object of the present invention is to provide a bellows air damper that has all of the following properties: liquid resistance to fuel, gas barrier properties, and bending durability. [Means for solving the problem]

[0008] The bellows air damper disclosed in the present application is a bellows air damper having axially continuous peaks and valleys, and comprises, from the inside to the outside, an inner layer, a first adhesive layer, an intermediate layer, a second adhesive layer, and an outer layer, the inner layer and the intermediate layer being made of ethylene-vinyl alcohol copolymer, and the outer layer being made of fluororesin. [Effects of the Invention]

[0009] According to the above configuration, a bellows air damper can be provided that has all of the following properties: liquid resistance to fuel, gas barrier properties, and bending durability. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a side cross-sectional view of a bellows air damper according to an embodiment of the present invention. [Figure 2] FIG. 2 is a detailed view of part A of the bellows air damper shown in FIG. [Figure 3] FIG. 2 is a detailed view of part B of the bellows air damper shown in FIG. [Figure 4] FIG. 2 is a detailed view of part C of the bellows air damper shown in FIG. [Figure 5] 1 is a table showing comparative evaluation data between a three-layer bellows air damper and a five-layer bellows air damper. DETAILED DESCRIPTION OF THE INVENTION

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings.

[0012] As shown in Figure 1, the bellows air damper 100 comprises a damper main body 1, a neck 2, and a fixed part 3. The damper main body 1 is composed of a substantially cylindrical side part 4 (bellows part) with continuous peaks and valleys in the axial direction, a bottom part 5 located at the axial end of the side part 4, and a ceiling part 6 located at the axial end of the side part 4 on the neck 2 side. The damper main body 1 is filled with a gas such as air and has continuous peaks and valleys in the axial direction, making it elastically deformable (expandable and contractible).

[0013] The bellows air damper 100 having the damper main body 1 is used in an automobile fuel supply system, for example, to suppress pulsation of fuel discharged from a fuel pump. Specifically, the bellows air damper 100 is used in an automobile fuel supply system, for example, by the following installation method. A fuel pump and a fuel injection device called an injector are connected by a fuel supply pipe. Connectors used for connecting the pipes are provided at key points along the fuel supply pipe. The bellows air damper 100 is disposed inside this connector, and the damper main body 1 expands and contracts in response to fluctuations in fuel pressure, thereby suppressing fuel pulsation. A damper called a pulsation damper for suppressing fuel pulsation is also connected to the fuel supply pipe. As an alternative to disposing the bellows air damper inside the connector, the bellows air damper 100 can be disposed externally instead of an external damper such as the pulsation damper. Note that the installation method of the bellows air damper 100 is not limited to these methods.

[0014] The fixing portion 3 formed at the tip of the bellows air damper 100 is intended to fix the bellows air damper 100 to any part of the fuel supply system where the bellows air damper 100 is to be placed, such as inside the connector. If the damper main body 1 can be fixed without the fixing portion 3, the fixing portion 3 may be cut and removed at the neck portion 2. In this case, the damper main body 1 becomes the bellows air damper.

[0015] The bellows air damper 100 is manufactured by a known molding method called blow molding. Blow molding is a process in which resin softened by heat is extruded into a pipe shape (the pipe-shaped resin is called a parison), compressed air is blown into the parison while the resin is soft, and the parison is pressed against a mold to cool and solidify, thereby molding the resin.

[0016] Here, the bellows air damper 100 (damper main body 1), which is a blow-molded product, has a five-layer structure consisting of, from the inside to the outside, an inner layer 9, a first adhesive layer 10, an intermediate layer 11, a second adhesive layer 12, and an outer layer 13, as shown in Fig. 2. The inner layer 9 is the layer that comes into contact with gas inside the damper main body 1, and the outer layer 13 is the layer that comes into contact with fuel such as gasoline. There are no particular limitations on the thickness of each of the inner layer 9, first adhesive layer 10, intermediate layer 11, second adhesive layer 12, and outer layer 13.

[0017] The inner layer 9 and intermediate layer 11 are each made of ethylene-vinyl alcohol copolymer (EVOH) from the viewpoint of imparting gas barrier properties to the bellows air damper 100. The outer layer 13 is made of fluororesin from the viewpoint of imparting liquid resistance to fuel to the bellows air damper 100.

[0018] Examples of the fluororesin include materials selected from ethylene-tetrafluoroethylene copolymer (ETFE), tetrafluoroethylene-ethylene-hexafluoropropylene copolymer (EFEP), tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer (THV), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), chlorotrifluoroethylene (CTFE)-tetrafluoroethylene (TFE) copolymer, and chlorotrifluoroethylene (CTFE)-tetrafluoroethylene (TFE)-perfluoroalkyl vinyl ether copolymer. The outer layer 13 may be formed using a material in which two or more of these fluororesins are blended.

[0019] The first adhesive layer 10 and the second adhesive layer 12 are each made of, for example, an adhesive polyamide resin. The adhesive polyamide resin is a polyamide resin containing an adhesive component. The first adhesive layer 10 is provided between the inner layer 9 and the intermediate layer 11 to prevent peeling between them. Similarly, the second adhesive layer 12 is provided between the intermediate layer 11 and the outer layer 13 to prevent peeling between them. Examples of adhesive polyamide resins include adhesive polyamide 6 resins (PA6), adhesive polyamide 11 resins (PA11), adhesive polyamide 12 resins (PA12), adhesive polyamide 610 resins (PA610), and adhesive polyamide 612 resins (PA612). In addition to adhesive polyamide resins, adhesive polyethylene resins and adhesive polypropylene resins may also be selected as materials for forming the adhesive layers 10 and 12.

[0020] Fig. 3 is a detailed view of part B of the bellows air damper 100. Fig. 4 is a detailed view of part C of the bellows air damper 100.

[0021] As described above, the bellows air damper 100 is manufactured by blow molding. Figure 4 shows a detailed cross section of the bellows air damper 100, where part C was the air blowing section. In the blow molding process, a pipe-shaped parison is formed. While the parison is not shown in the figure, an inner layer 9, a first adhesive layer 10, a middle layer 11, a second adhesive layer 12, and an outer layer 13 are formed on the parison from the inside to the outside of the parison. In other words, the parison has a five-layer structure.

[0022] The parison, which has a five-layer structure, is clamped (sandwiched) between a pair of molds from both sides in the radial direction, and compressed air is blown into the parison, causing it to expand and press against the molds.

[0023] By clamping the mold and blowing in compressed air as described above, the cross section of the center of the bottom 5 of the damper body 1 has a layered shape as shown in Figure 3. The innermost layer of the center of the bottom 5 of the damper body 1 is also EVOH, ensuring the gas barrier properties of the bottom 5. Furthermore, since the center of the bottom 5 does not undergo any particular bending movement, there is no need to worry about cracks.

[0024] In the final process, while the resin is still soft, the air blowing section is sealed by clamping it on both sides with a jig or similar inside a mold. The area that was the air blowing section is sealed as shown in the detailed cross section in Figure 4. As a result, the innermost layer in the center of the ceiling section 6 of the damper body 1 is also EVOH, ensuring gas barrier properties in the ceiling section 6 as well. Furthermore, since the neck section 2 does not undergo any particular bending movement, there is no need to worry about cracking.

[0025] FIG. 5 is a table showing comparative evaluation data between a three-layer bellows air damper (comparison example) and the five-layer bellows air damper 100.

[0026] The applicant of the present invention manufactured a three-layer bellows air damper (comparison example) and a five-layer bellows air damper 100 as shown below, and evaluated the manufactured bellows air dampers for (1) liquid resistance to gasoline, (2) gas barrier properties, and (3) bending durability.

[0027] (Specifications of the three-layer bellows air damper (comparison example)) 1.Materials for each layer Inner layer: Ethylene-vinyl alcohol copolymer (EVOH) Adhesive layer: adhesive polyamide resin (PA12) Outer layer: Fluorine resin (ethylene-tetrafluoroethylene copolymer (ETFE)) 2. Thickness Total thickness of the valleys of the peaks and valleys on the side: 0.10 mm or more and 0.20 mm or less Thickness of the inner layer in the valley: 0.03 mm or more and 0.06 mm or less Total thickness of the peaks and valleys on the side: 0.05 mm or more and 0.15 mm or less Thickness of the inner layer at the peak: 0.01 mm or more and 0.05 mm or less

[0028] (Specifications of the 5-layer bellows air damper 100) 1.Materials for each layer Inner layer 9: ethylene-vinyl alcohol copolymer (EVOH) First adhesive layer 10: adhesive polyamide resin (PA12) Intermediate layer 11: ethylene-vinyl alcohol copolymer (EVOH) Second adhesive layer 12: adhesive polyamide resin (PA12) Outer layer 13: Fluorine resin (ethylene-tetrafluoroethylene copolymer (ETFE)) 2. Thickness Total thickness of the valley portions 8 of the peak and valley portions of the side surface portion 4: 0.20 mm or more and 0.30 mm or less The thickness of the inner layer 9 in the valley portion 8: 0.03 mm or more and 0.06 mm or less The thickness of the intermediate layer 11 in the valley portion 8 is 0.02 mm or more and 0.05 mm or less. Total thickness of the peaks 7 of the peaks and valleys of the side surface 4: 0.15 mm or more and 0.25 mm or less Thickness of the inner layer 9 in the ridge portion 7: 0.01 mm or more and 0.05 mm or less Thickness of the intermediate layer 11 at the ridge portion 7: 0.01 mm or more and 0.05 mm or less

[0029] The thickness of each part and layer, such as the total thickness of the valley portion 8, is the result of measuring the central cross section of the bellows air damper (Figure 1) using (or by) the measurement function of a digital microscope. In other words, the thickness of each part and layer, such as the total thickness of the valley portion 8, can be determined by the measurement function of the digital microscope.

[0030] As can be seen from Figure 5, the three-layer bellows air damper was satisfactory in terms of liquid resistance and gas barrier properties, but lacked flexural durability. On the other hand, the five-layer bellows air damper 100 was satisfactory in all of these properties. In the five-layer bellows air damper 100, cracks occurred in the EVOH constituting the inner layer 9 (the innermost layer), just as in the three-layer bellows air damper. However, no cracks occurred in the EVOH constituting the middle layer 11. Therefore, in the three-layer bellows air damper, cracks occur in the inner layer with repeated expansion and contraction, causing gas to escape from the damper, resulting in deflation due to fuel pressure during actual use. On the other hand, in the five-layer bellows air damper 100, cracks may occur in the inner layer 9 with repeated expansion and contraction, but no cracks occur in the middle layer 11, preventing gas from escaping from the damper, preventing deflation due to fuel pressure during actual use. As described above, the bellows air damper 100 has all of the following properties: liquid resistance to gasoline, gas barrier properties, and bending durability.

[0031] The reason why cracks do not occur in the intermediate layer 11 is as follows: The adhesive layers (first adhesive layer 10, second adhesive layer 12) are provided inside and outside the intermediate layer 11, which can reduce stress concentration on the intermediate layer 11. This can prevent cracks from occurring in the intermediate layer 11.

[0032] Here, it is preferable that the fluororesin constituting the outer layer 13 is a material selected from ethylene-tetrafluoroethylene copolymer (ETFE), tetrafluoroethylene-ethylene-hexafluoropropylene copolymer (EFEP), and tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer (THV), and that the second adhesive layer 12 is composed of an adhesive polyamide resin.

[0033] The melting points of ethylene-tetrafluoroethylene copolymer (ETFE), tetrafluoroethylene-ethylene-hexafluoropropylene copolymer (EFEP), and tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer (THV), the melting point of the adhesive polyamide resin constituting the second adhesive layer 12, and the melting point of the ethylene-vinyl alcohol copolymer (EVOH) constituting the intermediate layer 11 are approximately the same. Therefore, when the resin constituting intermediate layer 11 is ethylene-vinyl alcohol copolymer (EVOH), if the fluororesin constituting outer layer 13 is a material selected from ethylene-tetrafluoroethylene copolymer (ETFE), tetrafluoroethylene-ethylene-hexafluoropropylene copolymer (EFEP), and tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer (THV), and if second adhesive layer 12 is composed of adhesive polyamide resin, a laminate can be formed by simultaneously extruding materials with similar melting points, increasing the affinity between intermediate layer 11, second adhesive layer 12, and outer layer 13 and improving adhesion and moldability. As a result, peeling between the layers can be more effectively prevented.

[0034] Furthermore, when the second adhesive layer 12 is made of an adhesive polyamide resin, it is preferable that the first adhesive layer 10 is also made of an adhesive polyamide resin. By making the adhesive layers 10, 12 out of the same type of resin material, it becomes easier to prepare the resin material when manufacturing the bellows air damper 100.

[0035] Furthermore, with regard to the side portion 4 (bellows portion) of the damper main body 1, it is preferable that the total thickness (thickness) of the valley portion 8 of the peak-valley portion is 0.20 mm or more and 0.30 mm or less, and the total thickness (thickness) of the peak portion 7 of the peak-valley portion is 0.15 mm or more and 0.25 mm or less.

[0036] The side surface portion 4 (bellows portion) is a particularly problematic portion in terms of the flexural durability of the bellows air damper 100. Furthermore, the valley portions 8 of the peak-valley portions that form the side surface portion 4 are located more inward than the peak portions 7, and therefore are typically thicker than the peak portions 7 during blow molding. If the peak-valley portions are too thick, flexural durability deteriorates and cracks are more likely to occur in the peak-valley portions. Therefore, it is preferable that the total thickness (thickness) of the valley portions 8 of the peak-valley portions be 0.20 mm or more and 0.30 mm or less, and that the total thickness (thickness) of the peak portions 7 of the peak-valley portions be 0.15 mm or more and 0.25 mm or less. This further reduces the occurrence of cracks in the side surface portion 4 (bellows portion).

[0037] Preferably, the thickness of the intermediate layer 11 in the valley portions 8 is 0.02 mm or more and 0.05 mm or less, and the thickness of the intermediate layer 11 in the peak portions 7 is 0.01 mm or more and 0.05 mm or less. The ethylene-vinyl alcohol copolymer (EVOH) constituting the intermediate layer 11 is a hard and brittle resin, and if the thickness of the peaks and valleys is too large, the flexural durability deteriorates and cracks are more likely to occur in the peaks and valleys. Therefore, by specifying the thickness of the intermediate layer 11 in the peaks and valleys as described above, it is possible to further prevent cracks from occurring in the intermediate layer 11.

[0038] The present invention is not limited to the above-described embodiments, and elements of the above-described embodiments can be appropriately combined or various modifications can be made to the above-described embodiments without departing from the spirit of the present invention.

[0039] For example, the above embodiment can be modified as follows.

[0040] The bellows air damper 100 (damper main body 1) has a generally cylindrical shape with axially continuous peaks and valleys (bellows portion). Alternatively, the bellows air damper may have a generally polygonal cylindrical shape, such as a generally rectangular cylindrical bellows air damper with axially continuous peaks and valleys (bellows portion). Alternatively, the bellows air damper may have a generally elongated cylindrical shape with axially continuous peaks and valleys (bellows portion).

[0041] The bellows air damper 100 (damper body 1) has a five-layer structure. It is also possible to add more layers to make the bellows air damper have six or more layers.

[0042] The fixed portion 3 constituting the bellows air damper 100 has a shape that includes an annular flange portion 3a, but the shape of the fixed portion 3 is not particularly limited. [Explanation of symbols]

[0043] 7: Yamabe 8: Valley 9: Inner layer 10: First adhesive layer 11: Middle class 12:Second adhesive layer 13: Outer layer 100: Bellows air damper

Claims

1. A bellows air damper having axially continuous peaks and valleys, a damper body having the peaks and valleys and having a gas sealed therein; The damper main body is The gas supply device includes, from the inside to the outside, an inner layer in contact with the gas, a first adhesive layer, an intermediate layer, a second adhesive layer, and an outer layer; The damper main body is The gas is sealed inside only the damper body, the inner layer and the intermediate layer are made of an ethylene-vinyl alcohol copolymer; the outer layer is made of a fluororesin, a thickness of the valley portion of the peak-valley portion is 0.20 mm or more and 0.30 mm or less; the thickness of the peaks of the valleys is 0.15 mm or more and 0.25 mm or less; the thickness of the intermediate layer at the valley portions is 0.02 mm or more and 0.05 mm or less, and the thickness of the intermediate layer at the peak portions is 0.01 mm or more and 0.05 mm or less; Bellows air damper.

2. 2. The bellows air damper according to claim 1, the fluororesin is a material selected from the group consisting of ethylene-tetrafluoroethylene copolymer, tetrafluoroethylene-ethylene-hexafluoropropylene copolymer, and tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer; The second adhesive layer is made of an adhesive polyamide resin. Bellows air damper.

3. 3. The bellows air damper according to claim 1, The first adhesive layer is made of an adhesive polyamide resin. Bellows air damper.

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