Vehicle carpet

Abstract

A vehicle carpet (10) is configured by comprising a skin layer (24) and a vibration-damping sheet (20), and is placed on a floor panel (14). The vibration-damping sheet (20) has an air-impermeable and flexible sheet body (30), and a plurality of supports (32) that are formed, at intervals from each other, to protrude downward from the sheet body (30) and that, at the respective leading-end surfaces, come into contact with the floor panel (14) so as to support the sheet body (30). The skin layer (24) is configured to be joined to the vibration-damping sheet (20) with or without a sound-absorbing layer (22) therebetween. Thus, space saving can be achieved while ensuring soundproof and vibration-proof performance on the floor of the vehicle.

Description

Vehicle carpet

[0001] The present invention relates to a vehicle carpet.

[0002] For example, in vehicles, noise suppression members are provided in the sections (floor panels) that divide the vehicle compartment to prevent noise and vibration from the outside of the vehicle or the vehicle's drive unit from being transmitted into the vehicle compartment. Sound-absorbing and sound-insulating materials are used to suppress noise in the high-frequency range, while vibration-damping and vibration-reducing materials are used to suppress noise in the lower frequency range than can be addressed by these sound-absorbing and sound-insulating materials, specifically road noise and engine noise (noise in the relatively low frequency range). For example, Patent Document 1 listed below discloses a sheet primarily intended to damp vibrations in structural sheets. The vibration-damping sheet described in Patent Document 1 listed below consists of a flexible heavy sheet and a viscoelastic support layer firmly bonded to the heavy sheet, with the support layer formed from multiple polygonal support structures. The multiple support structures are characterized by forming a maze-like space horizontally connected between the structural sheet (e.g., floor panel) and the heavy sheet. The vibration-damping sheet described in Patent Document 1 exhibits vibration-damping performance by vibrating itself, generating acoustic resonance in space, and generating friction between itself and the structural sheet.

[0003] U.S. Pat. No. 5,186,996

[0004] When a vibration-damping sheet such as that described in Patent Document 1 is used in a vehicle floor, a relatively thick and cushioned silencer (made of felt or urethane) is typically placed above the vibration-damping sheet placed on a floor panel, and a carpet is typically placed above the silencer. It is difficult to join these vibration-damping sheets, silencers, and carpets together as a single unit due to factors such as workability during manufacturing. This results in a large number of parts, which requires additional work to join each part, resulting in a large number of man-hours. Furthermore, the relatively thick silencer reduces the height of the interior space. In other words, when the height of the interior space is limited, specifically when a large-capacity battery is placed on the floor in an electric vehicle or the like, it is difficult to ensure the interior space is tall, making it difficult to adopt a floor structure consisting of the vibration-damping sheet, silencer, and carpet described above. On the other hand, removing or reducing the thickness of any of the vibration-damping sheet, silencer, or carpet can result in a decrease in the soundproofing and vibration-proofing performance and cushioning of the vehicle floor.

[0005] The present invention was made in consideration of such circumstances, and its object is to provide a vehicle carpet that can save space while ensuring soundproofing and vibration-proofing performance on the floor of a vehicle.

[0006] In order to solve the above problems, the vehicle carpet disclosed in this application has the following configuration: (1) A vehicle carpet placed on a floor panel of a vehicle includes: a vibration-damping sheet having an air-impermeable and flexible sheet body portion, and a plurality of support portions formed to protrude downward from the sheet body portion at intervals and each having a tip end surface in contact with the floor panel to support the sheet body portion, and a surface layer joined to the vibration-damping sheet with or without a sound-absorbing layer interposed therebetween.

[0007] The vehicle carpet disclosed in the present application is configured such that a surface layer constituting an upper layer and a vibration-damping sheet constituting a lower layer are bonded together, or such that, from top to bottom, a surface layer, a sound-absorbing layer, and a vibration-damping sheet are bonded together as a single unit. Because the vehicle carpet disclosed in the present application constitutes a floor structure on a floor panel by itself, it is relatively thin and the number of parts is reduced, which simplifies the carpet manufacturing process and the process of assembling it into a vehicle.

[0008] The "vibration-damping sheet" in the vehicle carpet disclosed herein forms a space between the seat body and the floor panel. Therefore, when the floor structure is represented by a vibration system (spring-mass system) model, the support portion functions as a spring element, thereby suppressing external vibrations. Specifically, it can suppress the transmission of vibrations and sounds mainly in the frequency range of 200 Hz to 630 Hz (hereinafter sometimes referred to as the "mid-frequency range") to the surface layer. Furthermore, because the vibration-damping sheet is made of a non-breathable material, it can suppress sounds in the high-frequency range, i.e., it has sound-insulating properties. The vibration-damping sheet can be made primarily of, for example, crude rubber, rubber, EPDM, EVA, polypropylene, polyethylene, polyvinyl chloride, olefin-based resin, or a mixture thereof.

[0009] When a sound-absorbing layer is interposed, it is thought that the thicker the sound-absorbing layer, the better the sound-proofing performance, but from the viewpoint of reducing the thickness of the vehicle carpet, it is desirable to make the sound-absorbing layer thinner. The sound-absorbing layer may be a silencer such as urethane, but it is desirable that it is a compressed fiber layer formed mainly of a compressed fiber aggregate.

[0010] The vehicle floor sheet disclosed herein can be formed primarily from, for example, crude rubber, rubber, EPDM, EVA, polypropylene, polyethylene, polyvinyl chloride, olefin-based resin, or a mixture thereof. The vehicle floor sheet disclosed herein is excellent in recyclability because the sheet body and the recessed protrusions are not made of different materials but are formed from a single plate-like member. Incidentally, the vehicle floor sheet disclosed herein can be formed by vacuum forming or roller forming instead of injection molding, which allows for shorter takt time during manufacturing compared to injection molding.

[0011] Furthermore, the vehicle carpet having the above-described configuration can be configured in the following various ways.

[0012] (2) The vehicle carpet according to (1), wherein the surface layer is joined to the vibration-damping sheet via the sound-absorbing layer, and the sound-absorbing layer has a thickness smaller than that of the surface layer and smaller than that of the vibration-damping sheet.

[0013] In a vehicle carpet having this configuration, although the sound absorbing layer is interposed between the surface layer and the vibration-damping sheet, the thickness of the sound absorbing layer is small, and the thickness of the vehicle carpet can be made relatively small.

[0014] (3) The vehicle carpet according to (2), wherein the sound absorbing layer is a compressed fiber layer formed mainly of a compressed fiber aggregate.

[0015] The "compressed fiber layer" in this vehicle carpet can be made of, for example, natural fibers, synthetic fibers, or a mixture of these fibers felted with binder fibers, i.e., so-called compressed felt. The thicker the compressed fiber layer, the better its soundproofing performance is considered to be. However, from the perspective of reducing the thickness of the vehicle carpet, it is desirable to make the compressed fiber layer as thin as possible. In view of this, it is desirable for the mass per unit area of ​​the compressed fiber layer to be 200 gsm or more and 500 gsm or less.

[0016] (4) A vehicle carpet according to any one of (1) to (3), wherein the vibration-damping sheet is made of a plate-like member that is non-breathable and flexible, and the plurality of support portions are recessed from the upper surface and protrude downward, and a plurality of hollow portions are formed between the vibration-damping sheet and the surface layer or the sound-absorbing layer, corresponding to each of the plurality of support portions.

[0017] A vehicle carpet having this configuration has a hollow space between the vibration-damping sheet (specifically, the support portion) and the surface layer or sound-absorbing layer, and the presence of this hollow space allows the support portion to undergo elastic deformation, such as collapse. In other words, compared to a vibration-damping sheet having a solid (non-hollow) upper side of the support portion, a vehicle carpet having this configuration has a softer support portion (a smaller spring constant as a spring element), making it possible to suppress vibrations and sounds in the frequency range below 200 Hz. Furthermore, the elasticity of the support portion of a vehicle carpet having this configuration enhances cushioning when occupants step on it, making it suitable for the vehicle carpet disclosed in this application, which does not have a padding material (a silencer such as urethane) in the floor structure.

[0018] The vibration-damping sheet in this vehicle carpet has excellent recyclability because the seat body and support part are not made of different materials but are formed from a single plate-like member. Incidentally, the vibration-damping sheet in this configuration can be formed by vacuum forming or roller forming instead of injection molding, which can shorten the takt time during manufacturing compared to injection molding.

[0019] (5) The vehicle carpet according to (4), wherein the support portion is tapered toward the tip.

[0020] In a vehicle carpet with this configuration, the outer dimensions of the support portion at the tip end are smaller than those at the base end (the seat body side of the vibration-damping sheet). If the support portion had a vertically erected wall portion, passengers might feel a stiffness or low-frequency vibrations when they step on it. However, because the vehicle carpet with this configuration does not have a vertically erected portion at the support portion, it is possible to improve cushioning and vibration-damping performance.

[0021] (6) The vehicle carpet according to (5), wherein the support portion has a downwardly convex curved shape.

[0022] In a vehicle carpet having this configuration, the support portion is more easily crushed, and cushioning and vibration-damping performance can be effectively improved.

[0023] (7) A vehicle carpet as described in any one of items (1) to (6), wherein, when the vibration-damping sheet is represented by a spring-mass system model, the seat main body corresponds to a mass element and the plurality of support portions correspond to spring elements, and the plurality of support portions have first support portions and second support portions having different spring constants as spring elements, and the vibration-damping sheet has a first region in which the first support portions having a relatively small spring constant are formed, and a second region in which the second support portions having a relatively large spring constant are formed.

[0024] In a vehicle carpet having this configuration, the first region of the vibration-damping sheet has superior vibration-damping performance in the low frequency range compared to the second region. Meanwhile, the second region can ensure vibration-damping performance and vibration-damping performance in the mid-frequency range compared to the first region. The configuration for making the spring constants of the first support portion and the second support portion different from each other is not particularly limited, and various methods can be used, such as making the planar view shapes of the support portions different, making the sizes different, or making the thickness different.

[0025] (8) The vibration-damping sheet is made of a plate-like member that is non-breathable and flexible, and the first support portion and the second support portion are formed in a shape that is recessed from the upper surface and protrudes downward, and a plurality of hollow portions are formed between the vibration-damping sheet and the surface layer or the sound-absorbing layer, corresponding to each of the plurality of support portions, and the first support portion is formed in a shape that tapers toward the tip, a vehicle carpet as described in (7).

[0026] This vehicle carpet has a structure in which the spring constant of the first support portion is different from the spring constant of the second support portion. In this vehicle carpet, the first support portion is tapered toward its tip, so that the first region using the first support portion has excellent cushioning properties as described above, and is also capable of suppressing vibrations and noise in the low-frequency range. This vehicle carpet is suitable for vehicle floors that have areas where occupants step on and areas where they do not.

[0027] (9) A vehicle carpet as described in (7) or (8), wherein the first area is a footwell area for a seated occupant, and the second area is the area excluding the footwell area.

[0028] In a vehicle carpet having this configuration, the area where occupants step is designated as the first area, and priority is given to cushioning and vibration-damping performance in the low frequency range, while the other areas ensure vibration-damping performance and vibration-damping performance in the mid frequency range. In other words, a vehicle carpet having this configuration can improve the vibration-damping performance of the entire vehicle compartment compared to a carpet using a vibration-damping sheet configured with the entire area designated as the first area.

[0029] According to the present invention, it is possible to provide a vehicle carpet that can ensure soundproofing and vibration-proofing performance on the floor of a vehicle while also achieving space saving.

[0030] Graph showing the relationship between vertical load and displacement in a vibration-damping sheet. Side cross-sectional view of the floor structure of Comparative Example 1. Graph showing transmission loss (sound insulation performance) in a vibration-damping sheet. Side cross-sectional view of the floor structure of Comparative Example 2. Side cross-sectional view of the floor structure of Comparative Example 3. Graph showing vibration transmissibility of a floor panel (vibration-damping performance of a vehicle carpet). Graph showing vibration transmissibility to a surface layer (vibration-damping performance of a vehicle carpet). Graph for comparing the vibration-damping performance of a first region and a second region of a vehicle carpet.

[0031] <Configuration of Vehicle Carpet> The vehicle carpet of this embodiment is a vehicle carpet 10 used in the floor of a vehicle (automobile). The vehicle carpet 10 will be described with reference to FIGS. 1 to 5. The floor of a vehicle 12 shown in FIG. 1 is primarily composed of a floor panel 14 made of metal, such as a thin steel plate. The vehicle carpet 10 of this embodiment is placed on the floor panel 14. Specifically, the vehicle carpet 10 is disposed in front of a rear seat 16 of the vehicle 12 shown in FIG. 1 and covers an area extending to the front of a driver's seat 17 and a passenger seat 18. The vehicle 12 is an electric vehicle, and a large-capacity drive battery is mounted on the floor. The floor panel 14 covers the upper surface of the battery. Therefore, the upper surface of the floor panel 14 is located higher than the floor panel of a vehicle without a battery (see FIG. 7). This may result in a reduction in the vertical size of the interior space. However, as shown in FIG. 2, the vehicle carpet 10 of this embodiment constitutes the floor structure on the floor panel 14 by itself, so the thickness of the components arranged on the floor panel 14 is smaller than in conventional configurations, and a wider interior space can be secured in the vertical direction.

[0032] As shown in Figure 2, the vehicle carpet 10 of this embodiment is formed by laminating and integrating a vibration-damping sheet 20 (backing layer), a sound-absorbing layer 22, and a surface layer 24 in this order from the floor panel 14 side (lower side). The vibration-damping sheet 20 and the sound-absorbing layer 22, and the sound-absorbing layer 22 and the surface layer 24 are bonded together with an adhesive, forming adhesive layers 26 and 28, respectively. The vibration-damping sheet 20, the sound-absorbing layer 22, and the surface layer 24 are bonded together with the adhesive layers 26 and 28, respectively, to form the integrated vehicle carpet 10.

[0033] The surface layer 24 is the layer disposed on the innermost side (upper side) of the vehicle and is intended to enhance the design and absorb sound. The surface layer 24 is not particularly limited, and various types of surface layers can be used, such as knee-pants surface layer, Deloitte surface layer, velour surface layer, plain surface layer, and tufted carpet surface layer. In this embodiment, knee-pants surface layer is used, and the mass per unit area is 350 gsm.

[0034] The sound-absorbing layer 22 is laminated below the surface layer 24 for sound absorption purposes. The sound-absorbing layer 22 is a so-called compressed fiber layer, and can be, for example, a compressed felt made by felting natural fibers, synthetic fibers, or a mixture of these fibers with a binder fiber. The compressed felt is preferably made from recycled fiber materials such as recycled cotton or other recycled fibers such as polyester, polyethylene, or polyethylene terephthalate (PET), a so-called synthetic fiber-recycled material. Specifically, the compressed fiber layer, the sound-absorbing layer 22, can be, for example, a synthetic fiber-recycled material mixed with a low-melting-point polyester as a binder, which is then heat-treated and pressed into a desired mat shape. Furthermore, the thicker the sound-absorbing layer 22, the better its sound-proofing performance is believed to be. However, due to limited vehicle interior space, it is desirable to reduce the thickness of the sound-absorbing layer 22, or in other words, its mass per unit area. In consideration of this, the sound absorbing layer 22 is made thinner than the skin layer 24 and thinner than the vibration-damping sheet 20 described below. Specifically, the sound absorbing layer 22 can have a mass per unit area of ​​200 gsm or more and 600 gsm or less, and preferably 200 gsm or more and 400 gsm or less. In this embodiment, the sound absorbing layer 22 is made of compressed PET felt and has a mass per unit area of ​​250 gsm.

[0035] The vibration-damping sheet 20 is the layer placed on the outermost side (lower side) of the room and is made of a non-breathable material. Its main purpose is to stop water from entering and to insulate sound from the outside. However, the vibration-damping sheet 20 has various functions in addition to sound insulation. The vibration-damping sheet 20 will be described in detail below.

[0036] As shown in Figures 2 to 5, the vibration-damping sheet 20 is formed from a non-breathable, flexible plate-like (flat) member, and is formed by vacuum forming or roller forming into a sheet member with multiple recesses from the upper surface and downward protrusions. That is, the vibration-damping sheet 20 has a sheet main body 30 that extends in a planar shape and multiple protrusions (first protrusions 32, second protrusions 33) that protrude downward from the sheet main body 30. Each of the first protrusions 32 and the second protrusions 33 is a recess-containing protrusion having a recess 32a, 33a on its upper surface. When the vibration-damping sheet 20 is bonded to the sound-absorbing layer 22, the recesses 32a, 33a form hollows 32S, 33S between the vibration-damping sheet 20 and the sound-absorbing layer 22. Furthermore, each of the multiple protrusions (first protrusion 32, second protrusion 33) contacts the floor panel 14 at its protruding tip (lower end) when the vehicle carpet 10 is placed on the floor panel 14. When the vehicle carpet 10 is placed on the floor panel 14, the first protrusion 32 and the second protrusion 33 contact the floor panel 14 at their protruding tips, and the seat main body 30 is spaced apart from the floor panel 14. In other words, the first protrusion 32 and the second protrusion 33 function as support parts that support the seat main body 30.

[0037] The vibration-damping sheet 20 is formed from a sheet member that is made of a base material such as crude rubber, rubber, EPDM, EVA, polypropylene, polyethylene, polyvinyl chloride, olefin-based resin, or a mixture thereof, to which fillers such as calcium carbonate and additives such as process oil are added, and that is kneaded and rolled into a plate-like shape. The mass per unit area of ​​the vibration-damping sheet 20 is set to be 1000 gsm or more and 5100 gsm or less, and preferably 1800 gsm or more and 2500 gsm or less.

[0038] In this embodiment, the vibration-damping sheet 20 has first protrusions (first support portions) 32 and second protrusions (second support portions) 33 formed within a predetermined range and having different shapes. Specifically, as shown in FIG. 1 , the vehicle carpet 10 of this embodiment has an area A1 in front of the driver's seat 17 and passenger's seat 18, an area A2 between the driver's seat 17 and passenger's seat 18 and the rear seat 16, and an area A3 below the driver's seat 17 and passenger's seat 18. The vibration-damping sheet 20 has first protrusions 32 formed in areas corresponding to areas A1 and A2, and a second protrusion 33 formed in an area corresponding to area A3. Note that areas A1 and A2 are footwells for occupants seated on the respective seats 16, 17, and 18, and are areas that may be stepped on by occupants' feet.

[0039] As shown in Figures 2 and 3, the first protrusions 32 formed in regions A1 and A2 have a circular, downwardly convex curved shape in plan view, or more simply, a hemispherical shape. In other words, the first protrusions 32 are tapered toward their tips, and contact the floor panel 14 at approximately a point. Meanwhile, the second protrusions 33 formed in region A3 have a cross shape in plan view and a bottomed, cylindrical (box-like) shape, as shown in Figures 4 and 5. Unlike the first protrusions 32, the second protrusions 33 do not have a tapered shape, and contact the floor panel 14 at a surface at their bottom surfaces (tip surfaces) 33b.

[0040] The first protrusion 32 will now be described in more detail. The outer diameter R of the first protrusion 32 is 10 mm or more and 30 mm or less. The outer diameter R is the outer diameter of the base end on the seat main body 30 side. The outer diameter R is also the diameter of the opening of the first protrusion 32. The protrusion dimension H1 of the first protrusion 32 from the seat main body 30 is 1 mm or more and 10 mm or less. The outer diameter R is preferably 15 mm or more and 20 mm or less. The protrusion dimension H1 is preferably 1.0 mm or more and 5.0 mm or less, and more preferably 1.0 mm or more and 2.5 mm or less. The outer dimension B of the second protrusion 33 is preferably the same as the outer diameter R of the first protrusion 32, and the protrusion dimension H2 is preferably the same as the protrusion dimension H1 of the first protrusion 32.

[0041] Furthermore, the distance L between adjacent first protrusions 32 and second protrusions 33 (more specifically, the distance between their centers) is set to 10 mm or more and 60 mm or less, and preferably 20 mm or more and 40 mm or less.

[0042] In the vehicle carpet 10 of this embodiment configured as described above, hollow portions 32S, 33S are formed between the vibration-damping sheet 20 and the sound-absorbing layer 22 (upper floor member) by the recesses 32a, 33a of the first protrusions 32 and the second protrusions 33. The hollow portions 32S, 33S allow the first protrusions 32 and the second protrusions 33 to undergo elastic deformation, such as crushing. In other words, the vehicle carpet 10 of this embodiment achieves a floor configuration that does not require a padding material (such as a silencer made of urethane) because the elastic force of the first protrusions 32 and the second protrusions 33 enhances cushioning when an occupant steps on the carpet. Furthermore, the first protrusions 32 are hemispherical and do not have a vertically extending wall portion like the second protrusions 33, so they provide greater cushioning than the second protrusions 33.

[0043] FIG. 6 shows the relationship between load and displacement when a load is applied to the vibration-damping sheet 20 from above. Note that FIG. 6 was calculated using a configuration in which the outer dimensions of the first protrusions 32 and the second protrusions 33 are 20 mm, the protrusion dimension is 2.0 mm, and the spacing between adjacent protrusions is 40 mm. As can be seen from FIG. 6 , both the portion where the first protrusions 32 are formed (first regions A1 and A2) and the portion where the second protrusions 33 are formed (second region A3) were confirmed to have lower rigidity and higher cushioning properties than the urethane shown by the dashed line. As described above, it was confirmed that the first protrusions 32 have higher cushioning properties than the second protrusions 33.

[0044] <Evaluation of Vehicle Carpet> As described above, the floor structure using the vehicle carpet 10 of this embodiment does not have a silencer, and there is a possibility that dealing with external vibrations and noise may be an issue. Below are shown the results of various evaluations conducted during the process of developing the vehicle carpet 10 of this embodiment.

[0045] (A) Sound Insulation Performance First, to predict sound insulation performance, the sound transmission loss was calculated for a floor structure as shown in FIGS. 2 and 4, in which the protrusion dimensions of the first protrusion 32 and the second protrusion 33 were 2 mm. The sound transmission loss was calculated by varying the mass per unit area of ​​the vibration-damping sheet 20. The results were also compared with the sound transmission loss for a conventional floor structure 40 shown in FIG. 7. The floor structure 40 of Comparative Example 1 is configured with a vibration-damping material 44, a silencer 45, and a carpet 46 stacked in this order on a floor panel 42. The carpet 46 has the same surface layer 24 and sound-absorbing layer 22 as the vehicle carpet 10 of this embodiment, but differs in its backing layer 47. The backing layer 47 is a non-breathable film with a mass per unit area of ​​400 gsm. The silencer 45 is a felt with a thickness of 10 mm and a mass per unit area of ​​1,000 gsm.

[0046] FIG. 8 shows the transmission loss of a first floor structure including a vehicle carpet 10 and a floor panel 14 in which the vibration-damping sheet 20 has a mass per unit area of ​​1800 gsm, and a second floor structure including a vehicle carpet 10 and a floor panel 14 in which the vibration-damping sheet 20 has a mass per unit area of ​​3000 gsm, for the vehicle carpet 10 of this embodiment. FIG. 8 also shows the transmission loss of the floor structure 40 of Comparative Example 1 with a dotted line. As can be seen from FIG. 8, the second floor structure (mass 3000 gsm) exhibited higher sound insulation performance than the floor structure 40 of Comparative Example 1. Furthermore, the first floor structure (mass 1800 gsm) exhibited slightly lower sound insulation performance than the floor structure 40 of Comparative Example 1, but still exhibited sufficient sound insulation performance. As mentioned above, the vibration-damping sheet 20 may have a mass per unit area of ​​1000 gsm or more and 5100 gsm or less. However, from the viewpoint of achieving both cushioning properties and sound insulation properties, it is considered preferable to set the thickness to 1800 gsm or more and 2500 gsm or less, based on the results of FIG.

[0047] (B) Vibration Suppression Performance (Vibration Damping Performance and Vibration Absorbing Performance) Next, the vibration suppression performance of the vehicle carpet 10 of this embodiment was evaluated. The vibration suppression performance was evaluated by placing a test piece of the vehicle carpet 10 of this embodiment on a panel, applying vibrations using a vibration excitation device, detecting the vibration transmissibility to the panel and the vibration transmissibility to the test piece P with respect to the input vibration, and checking the degree of attenuation of the resonance peak.

[0048] The vehicle carpet 10 of this embodiment (which has the second protruding portion 33) was compared with the floor structure 40 shown in FIG. 7 and two other floor structures 70 and 80. The floor structure 70 of Comparative Example 2, as shown in FIG. 9, has a configuration in which a silencer 74 and a carpet 75 are placed in this order on a floor panel 72. The carpet 75 has a configuration similar to that of the carpet 46 shown in FIG. 7. The silencer 74 is made of urethane with a thickness of 10 mm and a mass per unit area of ​​1000 gsm. The floor structure 80 of Comparative Example 3, as shown in FIG. 10, is a floor structure using a vibration-damping sheet 82 with a configuration similar to that of the vibration-damping sheet 20 of the vehicle carpet 10 of this embodiment. The vibration-damping sheet 82, a silencer 83, and a carpet 84 are placed in this order on the floor panel 14. The carpet 84 has a configuration similar to that of the carpet 46 shown in FIG. 7. The silencer 83 is made of felt having a thickness of 5 mm and a mass per unit area of ​​300 gsm.

[0049] Figure 11 shows the vibration transmission rate to the panel, i.e., the vibration-damping performance of the floor panel. The vehicle carpet 10 of this embodiment and the floor structure 80 of Comparative Example 3, which uses the same vibration-damping sheet 82 as this embodiment, were confirmed to have excellent vibration-damping performance, effectively attenuating resonance peaks compared to the conventional floor structures 40 and 70 of Comparative Examples 1 and 2. Figure 12 also shows the vibration transmission rate to the test piece, i.e., the vibration-damping performance, which is the vibration-suppressing effect on the surface layer 24. It was confirmed that the vehicle carpet 10 of this embodiment effectively attenuated resonance peaks in the frequency band of 200 Hz or higher.

[0050] 13 is a graph comparing the vibration transmissibility (thick solid line) of the first regions A1 and A2 where the first protrusions 32 are formed with the vibration transmissibility (thin solid line) of the second region A3 where the second protrusions 33 are formed in the vehicle carpet 10 of this embodiment. The vibration transmissibility of the second region A3 is 0 dB or less in the frequency band of 200 Hz or higher. In contrast, the vibration transmissibility of the first regions A1 and A2 is 0 dB or less in the frequency band of 80 Hz or higher. In other words, it was confirmed that the first regions A1 and A2 where the hemispherical first protrusions 32 are formed can also suppress vibrations in the low frequency range.

[0051] <Effects of the Vehicle Carpet> The vehicle carpet 10 of this embodiment, due to the presence of the vibration-damping sheet 20, can reduce thickness and achieve space savings while ensuring sound insulation performance, vibration-damping performance, and vibration-proofing performance, even when it is a single component of the floor structure on the floor panel 14 without being equipped with a silencer. In other words, a large interior space (height) can be ensured in an electric vehicle such as the vehicle 12, where space is difficult to secure.

[0052] Furthermore, in the vehicle carpet 10 of this embodiment, the vibration-damping sheet 20 has a first protrusion 32 in the first regions A1 and A2, and a second protrusion 33 in the second region A3. When the vibration-damping sheet 20 is represented by a spring-mass model, the seat main body 30 corresponds to the mass element, and the multiple protrusions 32 and 33 correspond to the spring elements. In the vehicle carpet 10 of this embodiment, the spring constant of the first protrusion 32 and the spring constant of the second protrusion 33 are different from each other. The spring constant of the first protrusion 32, which is tapered toward its tip, is smaller than the spring constant of the second protrusion 33, which is tubular and has a bottom. As a result, the vehicle carpet 10 of this embodiment has superior vibration-damping performance in the low frequency range in the first regions A1 and A2 compared to the second region A3. On the other hand, the second region A3 can ensure vibration-damping performance and vibration-damping performance in the mid-frequency range compared to the first regions A1 and A2. Therefore, the vehicle carpet 10 of this embodiment can improve the vibration-damping performance of the entire vehicle compared to when only one of the protrusions is formed. Furthermore, the first regions A1 and A2 have excellent cushioning properties, which can prevent a decrease in passenger comfort due to a reduced thickness of the floor structure.

[0053] Furthermore, in the vehicle carpet 10 of this embodiment, the vibration-damping sheet 20 is excellent in recyclability because the sheet main body 30 and the recess-containing protrusions 32, 33 are formed from a single sheet member rather than using different materials. Incidentally, this vibration-damping sheet 20 can be formed by vacuum forming or roller forming rather than injection molding, which allows for a shorter takt time during manufacturing compared to injection molding.

[0054] Other Embodiments The present invention is not limited to the above-described embodiment, and can be embodied in various forms with various modifications and improvements made based on the knowledge of those skilled in the art.

[0055] In the vehicle carpet 10 of the above embodiment, the first protrusions 32 and the second protrusions 33, which are the support parts of the vibration-damping sheet 20, are formed by recessing the upper surface and protruding downward, but this is not limiting. A configuration in which multiple support parts are provided on the underside of a flat sheet main body without any recesses is also possible.

[0056] In the above embodiment, the first protrusion 32 and the second protrusion 33, which are the support portions, are circular and cross-shaped in plan view, but are not limited thereto. For example, rectangular, polygonal, annular, etc. shapes may also be employed. Furthermore, the shape of the support portions tapering toward the tip is not limited to a hemispherical shape, and may be a cone shape.

[0057] In the vehicle carpet 10 of the above embodiment, a sound-absorbing layer 22 is provided between the vibration-damping sheet 20 and the surface layer 24, but this is not essential, and the vibration-damping sheet 20 may be bonded to the surface layer 24.

[0058] In the above embodiment, there is no particular limitation on the configuration for differentiating the spring constants of the first protruding portion 32 and the second protruding portion 33 of the vibration-damping sheet 20. For example, the spring constants may be different by making the sizes, plate thicknesses, etc. different.

[0059] In the above embodiment, an automobile is used as an example of a vehicle, but the vehicle carpet of the present invention can also be used for vehicles such as trains and recreational vehicles as ground vehicles, airplanes and helicopters as flying vehicles, and ships as sea vehicles.

[0060] 10...vehicle carpet (vehicle carpet), 12...vehicle (vehicle), 14...floor panel, 20...vibration-damping sheet, 22...sound-absorbing layer, 24...surface layer, 30...seat main body portion, 32...first protruding portion (first support portion), 32a...recess (hollow portion), 33...second protruding portion (second support portion), 33a...recess (hollow portion), A1, A2...first region (footwell portion), A3...second region

Claims

1. A vehicle carpet placed on a floor panel of a vehicle comprises: a non-breathable and flexible sheet body; a vibration-damping sheet having a plurality of support parts formed at intervals so as to protrude downward from the sheet body and whose tip surfaces contact the floor panel to support the sheet body; and a surface layer joined to the vibration-damping sheet with or without a sound-absorbing layer.

2. The vehicle carpet according to claim 1, wherein the surface layer is bonded to the vibration-damping sheet via the sound-absorbing layer, and the sound-absorbing layer has a thickness smaller than that of the surface layer and smaller than that of the vibration-damping sheet.

3. The vehicle carpet according to claim 2, wherein the sound absorbing layer is a compressed fiber layer formed mainly from a compressed fiber aggregate.

4. A vehicle carpet as claimed in any one of claims 1 to 3, wherein the vibration-damping sheet is made of a plate-like member that is non-breathable and flexible, the plurality of support parts are recessed from the upper surface and protrude downward, and a plurality of hollow parts are formed between the vibration-damping sheet and the surface layer or the sound-absorbing layer, corresponding to each of the plurality of support parts.

5. The vehicle carpet according to claim 4, wherein the support portion is tapered toward its tip.

6. The vehicle carpet according to claim 5, wherein the support portion has a downwardly convex curved shape.

7. A vehicle carpet as described in any one of claims 1 to 3, wherein, when the vibration-damping sheet is represented by a spring-mass system model, the seat main body corresponds to a mass element and the multiple support parts correspond to spring elements, and the multiple support parts have first support parts and second support parts which have different spring constants as spring elements, and the vibration-damping sheet has a first region in which the first support parts with a relatively small spring constant are formed, and a second region in which the second support parts with a relatively large spring constant are formed.

8. A vehicle carpet as described in claim 7, wherein the vibration-damping sheet is made of a plate-like member that is non-breathable and flexible, the first support portion and the second support portion are formed to have a shape that is recessed from the upper surface and protrudes downward, a plurality of hollow portions are formed between the vibration-damping sheet and the surface layer or the sound-absorbing layer, corresponding to each of the plurality of support portions, the first support portion is formed to have a shape that tapers towards the tip, and the second support portion is formed to have a cylindrical shape with a base.

9. A vehicle carpet as described in claim 7, wherein the first area is a foot well area for a seated occupant, and the second area is the area excluding the foot well area.

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