Sound-absorbing material for air cleaners and air cleaners

Abstract

This allows for a reduction in the number of parts and a reduction in intake noise at specific frequencies. [Solution] The sound-absorbing material 40 is attached to the bottom wall 11, which is the inner wall of the case 10 of the air cleaner of an internal combustion engine, to reduce the intake noise of the internal combustion engine. The sound-absorbing material 40 is a nonwoven fabric made of thermoplastic resin and comprises a main body 41 having breathable sound-absorbing layers 42, 43 and a shape-retaining layer 44 which is a sheet made of thermoplastic resin with a lower melting point than the sound-absorbing layers 42, 43, and is bonded to the fibers constituting the sound-absorbing layers 42, 43 by heat pressing while laminated on the sound-absorbing layers 42, 43, thereby maintaining the shape of the sound-absorbing layers 42, 43, and an attachment part formed by heat pressing a part of the nonwoven fabric and sheet, and attached to the bottom wall 11 such that an air layer 48 is formed between the main body 41 and the bottom wall 11. The shape-retaining layer 44 has through holes 45 that penetrate in the thickness direction of the shape-retaining layer 44.

Description

Technical Field

[0001] The present invention relates to a sound-absorbing material for an air cleaner and an air cleaner.

Background Art

[0002] An air cleaner for filtering foreign matters contained in intake air is provided in an intake passage of an in-vehicle internal combustion engine. Patent Document 1 discloses a sound-absorbing device for an air cleaner (hereinafter referred to as a sound-absorbing device) that reduces intake noise of an in-vehicle internal combustion engine. The sound-absorbing device disclosed in Patent Document 1 includes a sound-absorbing member that is a sheet-shaped non-woven fabric and a guide member that holds the sound-absorbing member. The guide member has a bowl shape with a plurality of ventilation holes and is housed in a case of the air cleaner. The guide member is made of synthetic resin. The sound-absorbing member is attached to the outer surface along the posture along the outer surface of the guide member. A plurality of claw portions for locking the sound-absorbing member are provided on the outer peripheral surface of the guide member.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the sound-absorbing material for an air cleaner, reduction of the number of parts and reduction of sound absorption at a specific frequency are required.

Means for Solving the Problems

[0005] The sound-absorbing material for an air cleaner, which solves the above problems, is attached to the inner wall of the case of an air cleaner of an internal combustion engine to reduce intake noise of the internal combustion engine, and comprises a main body having a nonwoven fabric made of thermoplastic resin, a breathable sound-absorbing layer, and a sheet made of thermoplastic resin having a lower melting point than the sound-absorbing layer, and a shape-retaining layer that maintains the shape of the sound-absorbing layer by being bonded to the fibers constituting the sound-absorbing layer when laminated on the sound-absorbing layer and heat-pressed, and an attachment part formed by heat-pressing a part of the nonwoven fabric and the sheet, and attached to the inner wall such that an air layer is formed between the main body and the inner wall, wherein the shape-retaining layer has through holes that penetrate in the thickness direction of the shape-retaining layer.

[0006] According to this configuration, the main body of the sound-absorbing material is a nonwoven fabric made of thermoplastic resin, and has a breathable sound-absorbing layer and a shape-retaining layer laminated on the sound-absorbing layer. When sound waves of intake noise from an internal combustion engine travel through the sound-absorbing layer, the vibrational energy of the sound waves is converted into vibrational energy of the fibers of the nonwoven fabric, and then converted into thermal energy, thereby reducing the intake noise.

[0007] Furthermore, the sheet that forms the shape-retaining layer is heat-pressed while laminated onto the nonwoven fabric that forms the sound-absorbing layer, thereby bonding it to the fibers that make up the sound-absorbing layer. This maintains the shape of the sound-absorbing layer.

[0008] Here, the sound-absorbing material includes a mounting portion formed by heat-pressing a part of the nonwoven fabric and sheet. When the mounting portion is attached to the inner wall of the air cleaner case, an air layer is formed between the main body and the inner wall. Thus, a Helmholtz resonator is formed by the through-hole in the main body, or the part of the main body including the through-hole, and the air layer. This reduces intake noise of a specific frequency in the intake passage.

[0009] The specific frequency mentioned above is determined by the volume of the air layer, the cross-sectional area of ​​the through-hole, and the thickness of the main body. Therefore, it is possible to reduce the number of parts and reduce intake noise at specific frequencies.

[0010] Furthermore, a sound-absorbing material for an air cleaner to solve the above problems is a sound-absorbing material for an air cleaner that is attached to the inner wall of the case of an air cleaner of an internal combustion engine to reduce the intake noise of the internal combustion engine, and is a nonwoven fabric comprising thermoplastic first resin fibers and thermoplastic second resin fibers having a lower melting point than the first resin fibers, wherein the first resin fibers are bonded to each other via the second resin fibers by heat pressing, and comprises a main body having a breathable sound-absorbing layer, and an attachment part formed by heat pressing a part of the nonwoven fabric and attached to the inner wall such that an air layer is formed between the main body and the inner wall, wherein the main body has through holes penetrating in the thickness direction of the sound-absorbing layer.

[0011] According to this configuration, the main body of the sound-absorbing material is a nonwoven fabric containing first and second resin fibers, and has a breathable sound-absorbing layer. When sound waves of intake noise from an internal combustion engine travel through the sound-absorbing layer, the vibrational energy of the sound waves is converted into vibrational energy of the fibers of the nonwoven fabric, and then converted into thermal energy, thereby reducing the intake noise.

[0012] Furthermore, the sound-absorbing layer is heat-pressed, causing the first resin fibers constituting the layer to bond to each other via second resin fibers. This maintains the shape of the sound-absorbing layer. Here, the sound-absorbing material includes a mounting portion formed by heat-pressing a part of the nonwoven fabric. When the mounting portion is attached to the inner wall of the air cleaner case, an air layer is formed between the main body and the inner wall. Thus, the through-hole in the main body and the air layer constitute a Helmholtz resonator. This reduces intake noise of a specific frequency in the intake passage. The specific frequency is defined by the volume of the air layer, the cross-sectional area of ​​the through-hole, and the length of the through-hole.

[0013] Therefore, it is possible to reduce the number of parts and reduce intake noise at specific frequencies. Furthermore, an air cleaner for solving the above problems is an air cleaner provided in the intake passage of an internal combustion engine, comprising a case having an inlet, a cap having an outlet, a filter element provided between the case and the cap, and a sound-absorbing material for the air cleaner, wherein an air layer is formed between the main body and the inner wall.

[0014] This configuration allows for similar effects to those of the two aforementioned sound-absorbing materials for air cleaners. [Brief explanation of the drawing]

[0015] [Figure 1] Figure 1 is a cross-sectional view of the air cleaner according to the first embodiment. [Figure 2] Figure 2 is a plan view of the sound-absorbing material shown in Figure 1. [Figure 3] Figure 3 is a cross-sectional view of the main body of the sound-absorbing material and the bottom wall of the case along the line 3-3 in Figure 2. [Figure 4] Figure 4 is a graph showing the relationship between the 1 / 3 octave band center frequency of intake noise inside the air cleaner and the reduction in volume. [Figure 5] Figure 5 is a cross-sectional view of the main body and bottom wall of the case of the sound-absorbing material according to the second embodiment. [Figure 6] Figure 6 is a cross-sectional view of the main body of the sound-absorbing material and the bottom wall of the case in the modified example. [Modes for carrying out the invention]

[0016] <First Embodiment> The sound-absorbing material for the air cleaner and the air cleaner according to the first embodiment will be described below with reference to Figures 1 to 4.

[0017] As shown in Figure 1, the air cleaner is installed in the intake passage of the vehicle's internal combustion engine. The air cleaner comprises a case 10 having an inlet 15, a cap 20 having an outlet 25, a filter element 30 provided between the case 10 and the cap 20, and a sound-absorbing material 40.

[0018] <Case 10> Case 10 has a bottom wall 11, a peripheral wall 12 continuous with the periphery of the bottom wall 11, an opening 13 surrounded by the upper edge of the peripheral wall 12, a flange 14 continuous with the upper edge of the peripheral wall 12, and an inlet 15. The inlet 15 is connected to the peripheral wall 12.

[0019] The bottom wall 11 has an attachment surface 112 to which a sound-absorbing material 40 described later is attached, and a recess 111 recessed with respect to the attachment surface 112. An attachment hole 113 penetrating the bottom wall 11 is opened in the attachment surface 112.

[0020] Case 10 is formed of a hard resin material. <Cap 20> Cap 20 has a top wall 21, a peripheral wall 22 continuous with the periphery of the top wall 21, an opening 23 surrounded by the lower edge of the peripheral wall 22, a flange 24 continuous with the lower edge of the peripheral wall 22, and an outlet 25. The outlet 25 is connected to the peripheral wall 22.

[0021] Cap 20 is formed of a hard resin material. <Filter element 30> The filter element 30 has a filtering portion 31 and a sealing portion 32. The filtering portion 31 has a shape in which a filter medium such as filter paper or non-woven fabric is folded into pleats. The sealing portion 32 is provided over the entire outer peripheral edge of the filtering portion 31. The sealing portion 32 is formed of a foamed resin material with independent bubbles.

[0022] <Sound-absorbing material 40> As shown in FIGS. 1 and 2, the sound-absorbing material 40 has a main body portion 41 and an attachment portion 46. As shown in FIG. 2, the sound-absorbing material 40 of the present embodiment is substantially rectangular in plan view. Note that the plan view shape of the sound-absorbing material 40 is not limited to a substantially rectangular shape in plan view, and may be other shapes such as a substantially triangular shape in plan view. Further, the shape of the sound-absorbing material 40 may be a three-dimensional shape having a portion facing the peripheral wall 12 in addition to the bottom wall 11.

[0023] As shown in Figure 3, the main body 41 has sound-absorbing layers 42, 43 and a shape-retaining layer 44. The sound-absorbing layers 42 and 43 are nonwoven fabrics made of thermoplastic resin and are breathable. The shape-retaining layer 44 is a thermoplastic resin sheet with a lower melting point than the sound-absorbing layers 42 and 43. By heat-pressing it while laminated on the sound-absorbing layers 42 and 43, it bonds to the fibers constituting the sound-absorbing layers 42 and 43, thereby maintaining the shape of the sound-absorbing layers 42 and 43.

[0024] In this embodiment, the shape-retaining layer 44 is sandwiched between the first sound-absorbing layer 42 and the second sound-absorbing layer 43. The sound-absorbing layers 42 and 43 are made of, for example, polyethylene terephthalate (PET). The shape-retaining layer 44 is made of, for example, polyethylene (PE).

[0025] The shape-retaining layer 44 has through holes 45 that penetrate in the thickness direction of the shape-retaining layer 44. The through-holes 45 penetrate both the shape-retaining layer 44 and the sound-absorbing layers 42 and 43 in the thickness direction and have the same cross-sectional shape in the thickness direction. The inner diameter of the through-holes 45 in this embodiment is 8 mm. The spacing between the through-holes 45 is 30 mm.

[0026] The mounting portion 46 is formed by heat-pressing a part of the nonwoven fabric and sheet. The mounting portion 46 is attached to the bottom wall 11 such that an air layer 48 is formed between the main body portion 41 and the bottom wall 11.

[0027] The bottom wall 11 of this embodiment corresponds to the "inner wall of the case" in the section on means for solving the above problem. In this embodiment, the mounting portion 46 is provided on the outer periphery of the main body portion 41. The mounting portion 46 is provided with a hole 47 that penetrates the mounting portion 46 in the thickness direction. With the main body portion 41 covering the recess 111 of the bottom wall 11, the mounting member 50 is inserted from the inside of the case 10 into the hole 47 of the mounting portion 46 and the mounting hole 113 of the bottom wall 11, thereby attaching the mounting portion 46 to the mounting surface 112 of the bottom wall 11. An air layer 48 is formed between the main body portion 41 and the recess 111 of the bottom wall 11.

[0028] The sound-absorbing material 40 is formed by heat-pressing a laminate of a sheet that will serve as a shape-retaining layer 44 onto a nonwoven fabric that will serve as a sound-absorbing layer 42, 43, and then forming through holes 45 and 47 by machining.

[0029] <Operation of this embodiment> The main body 41 of the sound-absorbing material 40 is a nonwoven fabric made of thermoplastic resin and has breathable sound-absorbing layers 42 and 43 and a shape-retaining layer 44 laminated on the sound-absorbing layers 42 and 43. When sound waves of intake noise from an internal combustion engine travel through the sound-absorbing layers 42 and 43, the vibrational energy of the sound waves is converted into vibrational energy of the fibers of the nonwoven fabric, and then converted into thermal energy, thereby reducing the intake noise (sound absorption effect).

[0030] Furthermore, the sheet that forms the shape-retaining layer 44 is heat-pressed while laminated onto the nonwoven fabric that forms the sound-absorbing layers 42 and 43, thereby bonding to the fibers that make up the sound-absorbing layers 42 and 43. This maintains the shape of the sound-absorbing layers 42 and 43.

[0031] Here, the sound-absorbing material 40 includes a mounting portion 46 formed by heat-pressing a part of the nonwoven fabric and sheet. When the mounting portion 46 is attached to the bottom wall 11 of the air cleaner case 10, an air layer 48 is formed between the main body 41 and the bottom wall 11. Thus, a Helmholtz resonator is formed by the through-hole 45 of the main body 41 and the air layer 48. As a result, intake noise of a specific frequency in the intake passage is reduced (sound-dampening effect).

[0032] The specific frequency mentioned above is determined by the volume of the air layer 48, the cross-sectional area of ​​the through-hole 45, and the length of the through-hole 45, i.e., the thickness of the main body 41. Figure 4 shows the relationship between the 1 / 3 octave band center frequency (Hz) and the reduction in volume (dB) of the intake sound inside the air cleaner.

[0033] The solid line in Figure 4 represents the measurement results for the air cleaner equipped with the sound-absorbing material 40 of this embodiment. The dashed line in Figure 4 represents the measurement results for the air cleaner of the first comparative example, which is equipped with sound-absorbing material that does not have through holes 45. The dashed line in Figure 4 represents the measurement results for the air cleaner of the second comparative example, which is not equipped with sound-absorbing material.

[0034] As shown by the solid lines in Figure 4, it was confirmed that the air cleaner of this embodiment reduces noise more significantly at 1250Hz, 2000Hz, and 2500Hz than the air cleaner of the first comparative example which has sound-absorbing material without through holes 45.

[0035] <Effects of this embodiment> (1-1) The sound-absorbing material 40 comprises a main body portion 41 having sound-absorbing layers 42, 43 and a shape-retaining layer 44, and a mounting portion 46. The shape-retaining layer 44 has through holes 45 that penetrate in the thickness direction of the shape-retaining layer 44.

[0036] With this configuration, the effects of the above embodiment are achieved, making it possible to reduce the number of parts and reduce intake noise at specific frequencies. (1-2) The through-hole 45 penetrates both the shape-retaining layer 44 and the sound-absorbing layers 42 and 43 in the thickness direction and has the same cross-sectional shape in the thickness direction.

[0037] With this configuration, the main body 41 is formed by heat-pressing a laminate of a sheet that will form a shape-retaining layer 44 onto a nonwoven fabric that will form sound-absorbing layers 42 and 43, and then forming through holes 45 by machining. Therefore, a sound-absorbing material 40 having through holes 45 with the same cross-sectional shape in the thickness direction can be easily formed.

[0038] (1-3) The sound-absorbing layers 42 and 43 are made of polyethylene terephthalate. The shape-retaining layer 44 is made of polyethylene. With this configuration, the polyethylene shape-retaining layer 44 is heat-pressed while laminated on the polyethylene terephthalate sound-absorbing layers 42 and 43, thereby bonding to the fibers constituting the sound-absorbing layers 42 and 43. This allows for easy realization of the sound-absorbing material 40.

[0039] (1-4) The air cleaner comprises a case 10, a cap 20, a filter element 30, and a sound-absorbing material 40. An air layer 48 is formed between the main body 41 and the bottom wall 11.

[0040] With this configuration, the same effects and advantages as those described in (1-1) to (1-3) can be achieved. <Second Embodiment> The air cleaner and sound-absorbing material for the air cleaner according to the second embodiment will be described below with reference to Figure 5.

[0041] In this embodiment, the configuration of the sound-absorbing material 140 differs from that of the first embodiment. Therefore, the following explanation will focus on the differences from the first embodiment. Furthermore, in this embodiment, the same reference numerals are used for components identical to those in the first embodiment, and for components corresponding to those in the first embodiment, the reference numeral "1**" is used, which is obtained by adding "100" to the reference numeral "**" of the components in the first embodiment, thereby omitting redundant explanations.

[0042] The sound-absorbing material 140 comprises a main body portion 141 and a mounting portion 46. The main body 141 has a breathable sound-absorbing layer 142. The sound-absorbing layer 142 is a nonwoven fabric containing thermoplastic first resin fibers and thermoplastic second resin fibers having a lower melting point than the first resin fibers, and the first resin fibers are bonded to each other via the second resin fibers by heat pressing.

[0043] The mounting portion 46 is formed by heat-pressing a part of the nonwoven fabric. The mounting portion 46 is attached to the bottom wall 11 such that an air layer 48 is formed between the main body portion 141 and the bottom wall 11.

[0044] The main body portion 141 has through holes 145 that penetrate the sound-absorbing layer 142 in the thickness direction. The first resin fiber is polyethylene terephthalate (PET). The second resin fiber is low-melting-point polyethylene terephthalate (PET), which has a lower melting point than polyethylene terephthalate.

[0045] <Operation of this embodiment> The main body 141 of the sound-absorbing material 140 is a nonwoven fabric containing first resin fibers and second resin fibers, and has a breathable sound-absorbing layer 142. When sound waves of intake noise from an internal combustion engine travel through the sound-absorbing layer 142, the vibrational energy of the sound waves is converted into vibrational energy of the fibers of the nonwoven fabric, and then converted into thermal energy, thereby reducing the intake noise (sound absorption effect).

[0046] Furthermore, the sound-absorbing layer 142 is heat-pressed, causing the first resin fibers constituting the sound-absorbing layer 142 to be bonded together via second resin fibers. This maintains the shape of the sound-absorbing layer 142.

[0047] Here, the sound-absorbing material 140 includes a mounting portion 46 formed by heat-pressing a part of the nonwoven fabric. When the mounting portion 46 is attached to the bottom wall 11 of the air cleaner case 10, an air layer 48 is formed between the main body 141 and the bottom wall 11. Thus, the through-hole 145 of the main body 141 and the air layer 48 constitute a Helmholtz resonator. This reduces intake noise of specific frequencies in the intake passage.

[0048] The specific frequency mentioned above is determined by the volume of the air layer, the cross-sectional area of ​​the through-hole, and the length of the through-hole. <Effects of this embodiment> (2-1) The sound-absorbing material 140 comprises a main body portion 141 having a sound-absorbing layer 142 and a mounting portion 46. The main body portion 141 has through holes 145 that penetrate in the thickness direction of the sound-absorbing layer 142.

[0049] With this configuration, the effects of the above embodiment are achieved, making it possible to reduce the number of parts and reduce intake noise at specific frequencies. (2-2) The first resin fiber is polyethylene terephthalate. The second resin fiber is low-melting-point polyethylene terephthalate, which has a lower melting point than polyethylene terephthalate.

[0050] With this configuration, the first resin fibers made of polyethylene terephthalate are suitably bonded to each other via the second fiber resin made of low-melting-point polyethylene terephthalate. Therefore, the sound-absorbing material 140 can be easily realized.

[0051] <Variation> This embodiment can be implemented with the following modifications. This embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0052] In the second embodiment, the first and second resin fibers are not limited to polyethylene terephthalate (PET), but may be other materials such as polypropylene (PP). In the first embodiment, either the first sound-absorbing layer 42 or the second sound-absorbing layer 43 can be omitted.

[0053] In the first embodiment, the sound-absorbing layer is not limited to polyethylene terephthalate (PET), but may be made of other thermoplastic resins such as polypropylene (PP) or acrylic. Furthermore, the nonwoven fabric constituting the sound-absorbing layer may be made of a mixture of multiple types of thermoplastic resin fibers. In addition, the thermoplastic resin nonwoven fabric constituting the sound-absorbing layer may be mixed with natural fibers such as hemp or rayon. Furthermore, the shape-retaining layer is not limited to polyethylene (PE), but may be made of a thermoplastic resin with a lower melting point than the thermoplastic resin constituting the sound-absorbing layer.

[0054] As shown in the modified example of the sound-absorbing material 40 in Figure 6, the through-hole 45 may penetrate only the shape-retaining layer 44 of the shape-retaining layer 44 that constitutes the main body 41, along with the sound-absorbing layers 42 and 43. Even in this case, since the sound-absorbing layers 42 and 43 are breathable, a Helmholtz resonator is formed by the portion of the main body 41 including the through-hole 45 and the air layer 48. This reduces intake noise of a specific frequency in the intake passage. As for the method of forming the through-hole 45, it is also possible to use a method in which the through-hole 45 is formed by the stress acting on the sheet when a laminate of nonwoven fabric constituting the sound-absorbing layers 42 and 43 and a thermoplastic resin sheet with a lower melting point than the sound-absorbing layers 42 and 43 is heat-pressed. Alternatively, it is also possible to use a method in which the through-hole 45 is formed in advance on the sheet by machining or other means.

[0055] In the above examples of modifications, redundant explanations are omitted by using the same reference numerals for components that are identical to or corresponding to the configuration of the first embodiment. [Explanation of Symbols]

[0056] 10... Cases 11...Bottom wall 12...Peripheral wall 13...Aperture 14…Flange 15...Inlet 20... Cap 21... Top wall 22...Peripheral wall 23…Aperture 24…Flange 25…Outlet 30…Filter element 31...filtration section 32...Seal part 40,140...sound-absorbing material 41,141…Main body 42…First sound-absorbing layer 43…Second sound-absorbing layer 44…Shape retention layer 45,145… through holes 46…Mounting part 47…hole 48...Air layer 50…Mounting parts 111…recess 112…Mounting surface 113…Mounting holes 142...Sound-absorbing layer

Claims

1. An air cleaner sound-absorbing material that is attached to the inner wall of the air cleaner case of an internal combustion engine to reduce the intake noise of the internal combustion engine, A main body having a nonwoven fabric made of thermoplastic resin, a breathable sound-absorbing layer, and a sheet made of thermoplastic resin with a lower melting point than the sound-absorbing layer, which maintains the shape of the sound-absorbing layer by being heat-pressed while laminated on the sound-absorbing layer and bonding to the fibers constituting the sound-absorbing layer, The nonwoven fabric and a portion of the sheet are formed by heat pressing, and the mounting portion is attached to the inner wall such that an air layer is formed between the main body and the inner wall, The shape-retaining layer has through holes that penetrate in the thickness direction of the shape-retaining layer. Sound-absorbing material for air cleaners.

2. The through-hole penetrates both the shape-retaining layer and the sound-absorbing layer in the thickness direction and has the same cross-sectional shape in the thickness direction. Sound-absorbing material for air cleaner according to claim 1.

3. The sound-absorbing layer is made of polyethylene terephthalate. The shape-retaining layer is made of polyethylene. The sound-absorbing material for an air cleaner according to claim 2.

4. An air cleaner sound-absorbing material that is attached to the inner wall of the air cleaner case of an internal combustion engine to reduce the intake noise of the internal combustion engine, A nonwoven fabric comprising thermoplastic first resin fibers and thermoplastic second resin fibers having a lower melting point than the first resin fibers, wherein the first resin fibers are bonded to each other via the second resin fibers by heat pressing, and having a main body with a breathable sound-absorbing layer, The system includes a mounting portion formed by heat-pressing a portion of the nonwoven fabric, which is attached to the inner wall such that an air layer is formed between the main body and the inner wall, The main body portion has through holes that penetrate in the thickness direction of the sound-absorbing layer. Sound-absorbing material for air cleaners.

5. The first resin fiber is polyethylene terephthalate, The second resin fiber is a low-melting-point polyethylene terephthalate, which has a lower melting point than the polyethylene terephthalate. The sound-absorbing material for an air cleaner according to claim 4.

6. An air cleaner installed in the intake passage of an internal combustion engine, A case with an inlet, A cap with an outlet, A filter element provided between the case and the cap, The air cleaner sound-absorbing material is provided according to any one of claims 1 to 5, An air layer is formed between the main body and the inner wall. Air cleaner.

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