Seat for vehicle floor

Abstract

This seat for a vehicle floor constitutes a floor of a vehicle and is interposed between two floor members (14, 22). The seat for a vehicle floor is composed of a plate-like member that is not permeable to air and is flexible, said seat for a vehicle floor comprising a seat body part (30) and a plurality of recess-containing protrusions (32) that are shaped so as to be recessed from the upper-surface side of the seat body part (30) and to protrude downward and are arranged at intervals from each other. The seat for a vehicle floor is configured to be installed in a state of being in contact with a lower floor member (14) at the lower ends of each of the plurality of recess-containing protrusions (32). Thus, space can be saved while soundproofing and vibration-proofing performance on the floor of the vehicle is ensured.

Description

Vehicle floor seats

[0001] The present invention relates to a vehicle floor sheet that constitutes the floor of a vehicle.

[0002] For example, in vehicles, noise suppression components are provided in the sections that define the vehicle cabin to prevent noise and vibration from the outside of the vehicle or from the vehicle's drive unit from being transmitted into the vehicle cabin. Sound-absorbing and sound-insulating materials are used to suppress noise in the high-frequency range, while vibration-proof and vibration-damping 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 an example of 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., a 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 it 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 on top of the vibration-damping sheet placed on a floor panel, and a surface layer (carpet) is typically placed on top of 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 components, which requires additional work to join each component, 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 sufficient height for the interior space, making it difficult to adopt a floor structure consisting of the vibration-damping sheet, silencer, and carpet described above. On the other hand, removing any of the vibration-damping sheets, silencers, or carpets or reducing their thickness can result in a decrease in the soundproofing and vibration-proofing performance and cushioning properties of the vehicle floor.

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

[0006] In order to solve the above problems, the vehicle floor sheet disclosed in the present application has the following configuration: (1) A vehicle floor sheet that constitutes the floor of a vehicle and is interposed between two layers of floor members, the vehicle floor sheet comprising: a sheet main body portion; and a plurality of recess-containing protrusions that are recessed from the upper surface of the sheet main body portion and protrude downward and are arranged at intervals from each other, the vehicle floor sheet being made of an air-impermeable and flexible plate-like member, and the vehicle floor sheet being placed in a state where the lower ends of each of the recess-containing protrusions are in contact with the floor member below.

[0007] Conventionally, seats with multiple protrusions on the underside of a plate-shaped seat body, such as those described in Patent Document 1, form a space between the seat body and the underlying floor material. Therefore, when the floor structure is represented by a vibration system (spring-mass system) model, the protrusions function as spring elements, thereby suppressing external vibrations. Specifically, they can suppress the transmission of vibrations and sounds in the frequency range of 200 Hz to 630 Hz (hereinafter sometimes referred to as the "mid-frequency range") to the upper floor material. Meanwhile, the vehicle floor seat disclosed in the present application has recesses formed on the upper surface of such protrusions to form recess-containing protrusions, creating a hollow between the recess-containing protrusions of the vehicle floor seat and the upper floor material. The presence of this hollow allows the recess-containing protrusions to undergo elastic deformation, such as crushing. In other words, compared to seats with the above configuration, the recess-containing protrusions are softer (having a smaller spring constant as a spring element), making it possible to suppress vibrations and sounds in the frequency range below 200 Hz. Furthermore, since the vehicle floor sheet disclosed in the present application is made of a non-breathable material, it is capable of suppressing high-frequency sounds, i.e., has sound insulation properties. Note that in the vehicle floor sheet disclosed in the present application, the planar shape of the recess-containing protrusion is not particularly limited. Various shapes such as a rectangular shape, a circular shape, an annular shape, a cross shape, etc. can be adopted.

[0008] The vehicle floor sheet disclosed in the present application can increase cushioning when an occupant steps on it due to the elastic force of the recessed protrusions, and it also makes it possible to remove padding materials (silencers such as felt or urethane) from floor structures using the vehicle floor sheet.

[0009] Although the vehicle floor sheet disclosed in the present application is not limited to being placed directly on a vehicle floor panel (an example of a lower floor member), it is desirable to use the sheet in a form in which it is placed directly on the floor panel, since placing the sheet directly on the floor panel enables vibration damping of the floor panel. Furthermore, the vehicle floor sheet disclosed in the present application can be used alone or can be joined to an upper floor member.

[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] The vehicle floor seat having the above-described configuration can be configured in the following various ways.

[0012] (2) The vehicle floor sheet according to (1), wherein the plurality of recess-containing protrusions include a plurality of first protrusions having a shape tapering toward a tip.

[0013] In a vehicle floor seat having this configuration, the recess-containing protrusion is, for example, curved or cone-shaped, and the outer dimensions of the tip end side are smaller than the outer dimensions of the base end side (the flat portion side of the seat that is the flat portion of the seat). If the recess-containing protrusion has a wall portion that stands up vertically, there is a risk that the occupant will feel hardness or low-frequency vibrations when stepping on it. In a vehicle floor seat having this configuration, since the recess-containing protrusion does not have a portion that stands up vertically, it is possible to improve cushioning and vibration-damping performance.

[0014] (3) The vehicle floor sheet according to (2), wherein the plurality of first protrusions have a downwardly convex curved shape.

[0015] In a vehicle floor sheet having this configuration, the recess-containing protrusions are more easily crushed, and cushioning and vibration-damping performance can be effectively improved.

[0016] (4) A vehicle floor sheet as described in (3), wherein the plurality of first protrusions have an outer diameter on the main body side of 10 mm or more and 30 mm or less, and a hemispherical shape with a protruding dimension from the flat plate portion of 1 mm or more and 10 mm or less.

[0017] It has been confirmed that a vehicle floor sheet having this configuration can suppress vibrations and sounds in the low frequency range of 80 Hz to 200 Hz, although its performance in suppressing mid-frequency vibrations and sounds and its vibration-damping performance are reduced compared to when a recess-containing protrusion with a large installation area on the lower floor member is used. In other words, a vehicle floor sheet having this configuration can suppress vibrations and sounds over a wide frequency range. From the perspective of achieving both cushioning and vibration-damping performance, the outer diameter of the recess-containing protrusion on the flat plate portion side is preferably 15 mm to 20 mm. Furthermore, from the perspective of reducing the thickness of the floor structure, the protrusion dimension from the flat plate portion is preferably 1.0 mm to 5.0 mm, and more preferably 1.0 mm to 2.5 mm.

[0018] (5) The vehicle floor sheet according to (4), wherein the plurality of first protrusions are formed with a distance between their centers of 10 mm or more and 60 mm or less.

[0019] A vehicle floor sheet having this configuration can suppress vibrations and noise over a wide frequency range while providing cushioning equivalent to that of urethane when stepped on by an occupant. From the perspective of achieving both cushioning and vibration-damping performance, a thickness of 20 mm to 40 mm is preferable.

[0020] (6) A vehicle floor sheet according to any one of (1) to (5), having a mass per unit area of ​​1000 gsm or more and 5100 gsm or less.

[0021] The vehicle floor seat having this configuration can ensure the performance of suppressing high-frequency vibrations and noise while also ensuring cushioning when an occupant steps on it. It is more preferable that the mass per unit area is 1800 gsm or more and 2500 gsm or less.

[0022] (7) A vehicle floor sheet as described in any one of (1) to (5) above, which is arranged in a state in which a space is formed between the plurality of recess-containing protrusions and the upper floor member.

[0023] In a vehicle floor sheet of this configuration, the space formed between the floor member and the recess-containing protrusion allows the recess-containing protrusion to undergo elastic deformation such that it is crushed, and the elastic force of such recess-containing protrusion can effectively improve cushioning and vibration-damping performance.

[0024] (8) A vehicle floor sheet as described in any one of (2) to (5), which is arranged such that a space is formed between the plurality of first protrusions and the upper floor member.

[0025] In a vehicle floor seat of this configuration, the space formed between the first protrusion and the floor member allows the first protrusion to undergo elastic deformation such as crushing, and the elastic force of this first protrusion can effectively improve cushioning and vibration-damping performance.

[0026] (9) A vehicle floor sheet according to (2), wherein the plurality of recess-containing protrusions include a second protrusion having a cylindrical shape with a bottom.

[0027] A vehicle floor seat having this configuration can improve the vibration isolation performance as a whole.

[0028] (10) A vehicle floor seat as described in (9), wherein the plurality of first protrusions and the plurality of second protrusions are each arranged so that a space is formed between them and the upper floor member.

[0029] In the vehicle floor seat having this configuration, the first protrusion and the second protrusion are allowed to undergo elastic deformation such that they are crushed due to the space formed between them and the floor member, and this elastic force allows the entire seat to have cushioning properties and vibration-damping performance.

[0030] According to the present invention, it is possible to provide a vehicle floor seat that can ensure soundproofing and vibration-proofing performance on the floor of a vehicle while also saving space.

[0031] 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.

[0032] <Configuration of Vehicle Carpet> The vehicle floor sheet of this embodiment is included in 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 floor structure (see FIG. 7) that does not have a battery. 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] The vibration-damping sheet 20 is the layer disposed on the outermost side (lower side) of the vehicle, and is made of a non-breathable material. Its main purpose is to stop water and to insulate sound from the outside. However, this vibration-damping sheet 20 (vehicle floor sheet) has various functions in addition to sound insulation. The backing layer 20 will be described in detail below.

[0037] 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.

[0038] 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.

[0039] 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 the areas A1 and A2, and a second protrusion 33 formed in an area corresponding to the area A3. The 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 the occupants' feet.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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 can enhance cushioning when an occupant steps on it by the elastic force of the first protrusions 32 and the second protrusions 33, thereby realizing a floor configuration that does not require a padding material (a silencer such as urethane). 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.

[0044] 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.

[0045] <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.

[0046] (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.

[0047] 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.

[0048] (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.

[0049] The vehicle carpet 10 of this embodiment (which has the second protruding portion 33 as the protruding portion) 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 stacked 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, uses a vibration-damping sheet 82 with a structure similar to that of the vibration-damping sheet 20 of the vehicle carpet 10 of this embodiment, and can be considered the second embodiment. This floor structure 80 has a configuration in which a vibration-damping sheet 82, a silencer 83, and a carpet 84 are stacked in this order on a 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.

[0050] Figure 11 shows the vibration transmission rate to the panel, i.e., the vibration-damping performance for damping the vibration of the floor panel. The vehicle carpet 10 of this embodiment and the floor structure 80 of Comparative Example 3, which uses a vibration-damping sheet 82 having the same structure as the vibration-damping sheet 20 of this embodiment, were confirmed to be able to effectively attenuate resonance peaks and have excellent vibration-damping performance compared to the conventional floor structures 40 and 70 of Comparative Examples 1 and 2. Furthermore, Figure 12 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 was able to effectively attenuate resonance peaks in the frequency band of 200 Hz or higher.

[0051] 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.

[0052] <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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] In the above embodiment, the first protrusion 32 and the second protrusion 33, which are the recess-containing protrusions, 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 recess-containing protrusion tapering toward the tip is not limited to a hemispherical shape, and may be a cone shape.

[0057] In the above embodiment, the vibration-damping sheet 20, which is a vehicle floor sheet, is used in a state where it is joined to the vehicle carpet 10, but it can also be used as a vehicle floor sheet alone, as in the floor structure 80 shown in Figure 10.

[0058] In the above embodiment, an automobile is used as an example of a vehicle, but the vehicle floor sheet 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 marine vehicles.

[0059] 10...vehicle carpet, 12...vehicle (vehicle), 14...floor panel, 20...vibration-damping sheet (vehicle floor sheet), 30...seat main body, 32...first protrusion (recess-containing protrusion), 32a...recess (hollow portion), 33...second protrusion (recess-containing protrusion), 33a...recess (hollow portion)

Claims

1. A vehicle floor sheet that forms the floor of a vehicle and is interposed between two layers of floor members, comprising: a sheet main body portion; and a plurality of recessed protrusions that are recessed from the upper surface of the sheet main body portion and protrude downward, and are arranged at intervals from each other; the vehicle floor sheet is made of a non-breathable and flexible plate-like member, and is placed so that the lower ends of each of the plurality of recessed protrusions are in contact with the floor member below.

2. A vehicle floor sheet according to claim 1, wherein the plurality of recess-containing protrusions include a plurality of first protrusions having a shape tapering toward a tip.

3. A vehicle floor sheet according to claim 2, wherein the plurality of first protrusions are formed in a downwardly convex curved shape.

4. A vehicle floor sheet as described in claim 3, wherein the plurality of first protrusions have an outer diameter on the main body side of 10 mm or more and 30 mm or less, and are hemispherical in shape with a protruding dimension from the flat plate portion of 1 mm or more and 10 mm or less.

5. A vehicle floor sheet according to claim 4, wherein the plurality of first protrusions are formed with a distance between their centers of 10 mm to 60 mm.

6. A vehicle floor sheet according to any one of claims 1 to 5, having a mass per unit area of ​​1000 gsm or more and 5100 gsm or less.

7. A vehicle floor sheet as claimed in any one of claims 1 to 5, arranged such that a space is formed between the plurality of recess-containing protrusions and the upper floor member.

8. A vehicle floor seat as claimed in any one of claims 2 to 5, which is arranged such that a space is formed between the plurality of first protrusions and the floor member above.

9. A vehicle floor sheet according to claim 2, wherein the plurality of recess-containing protrusions include a plurality of second protrusions each having a cylindrical shape with a bottom.

10. A vehicle floor seat according to claim 9, wherein the plurality of first protrusions and the plurality of second protrusions are arranged such that a space is formed between each of the first protrusions and the floor member above.

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