Vehicle seat and vibration reduction method thereof

Abstract

To enable weight saving and reduction of discomfort due to vibration transmitted to an occupant.SOLUTION: A vehicle seat installed in a vehicle includes a seat part 20 having: a vibration reduction member that reduces vibration transmitted to an occupant of the vehicle seat during traveling; and a seat frame 32 formed of at least one of CFRP, UD material, and a composite lamination resin material. The vibration reduction member is formed of a resin structure and / or CFRP. The vibration reduction member may include a tabular member 24 formed of CFRP.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a vehicle seat and a method for reducing vibrations thereof. [Background technology]

[0002] In order to improve the fuel efficiency of various vehicles, component development has been carried out to further reduce the weight of vehicle bodies, and various studies have been conducted to reduce the weight of vehicle seats, which account for a large proportion of the vehicle's weight. When reducing the weight of vehicle seats, it is not enough to simply aim for weight reduction; various characteristics must also be taken into consideration, such as the reduction in safety due to a decrease in strength, and among these, the safety of occupants must be given the utmost consideration. From this perspective, various technologies that take occupant safety into consideration have been proposed in the past (see, for example, Patent Documents 1 to 3).

[0003] Furthermore, one of the discomforts that occupants feel when riding in a vehicle is caused by vibration, and the use of dynamic dampers and the like is known as a technology for suppressing vibration in vehicle seats (see, for example, Patent Document 4). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6266320 [Patent Document 2] Patent No. 3507065 [Patent Document 3] Patent No. 6439724 [Patent Document 4] Japanese Patent Application Laid-Open No. 2004-116654 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the dynamic damper disclosed in Patent Document 4 requires a damper mass to absorb vibrations, which increases the weight of the vehicle seat. Furthermore, there have been no vehicle seats previously designed to reduce weight while also mitigating discomfort caused by vibrations transmitted to the occupant.

[0006] Therefore, an object of the present invention is to provide a vehicle seat having a structure that can reduce weight and reduce discomfort caused by vibrations transmitted to occupants, and a method for reducing vibrations therein. [Means for solving the problem]

[0007] One aspect of the present invention is a vehicle seat to be installed in a vehicle, a vibration reducing member that reduces vibrations transmitted to an occupant of the vehicle seat during driving; a seat frame made of at least one of CFRP, UD material, and composite laminated resin material; a seat having The vehicle seat has a vibration-reducing member made of a resin structure and / or CFRP.

[0008] With a vehicle seat having such a structure, vibrations transmitted to an occupant of the vehicle seat during driving can be reduced by the vibration-reducing member, thereby reducing discomfort caused by the vibrations transmitted to the occupant. Also, the seat frame (skeleton) can be made of at least one of CFRP, UD material, and composite laminated resin material, thereby reducing the weight.

[0009] In the vehicle seat as described above, the vibration reducing member may be formed of a resin structure.

[0010] In the vehicle seat described above, the resin structure may be a structure made of a metamaterial.

[0011] In the vehicle seat described above, the structure made of a metamaterial may include a resonator.

[0012] In the vehicle seat described above, the vibration reducing member may be made of CFRP.

[0013] In the vehicle seat as described above, the vibration reducing member may include a plate-shaped member made of CFRP.

[0014] In the vehicle seat as described above, the plate-shaped member may include a long CFRP leaf spring member.

[0015] In the vehicle seat as described above, the vibration reducing member may be a member that reduces vibrations in the range of at least 20 Hz to 50 Hz.

[0016] In the vehicle seat as described above, the seat portion may include a mesh upholstery and not include a urethane-type cushioning material.

[0017] Another aspect of the present invention is a method for reducing vibrations in a vehicle seat installed in a vehicle, the method comprising: The seat portion of the vehicle seat is a vibration reducing member that reduces vibrations transmitted to an occupant of the vehicle seat during driving; a seat frame made of at least one of CFRP, UD material, and composite laminated resin material; and a vibration reduction method in which the vibration reduction member is made of a resin structure and / or CFRP, and the vibration transmitted to the occupant is reduced by the vibration reduction member and the seat frame. [Effects of the Invention]

[0018] According to the present invention, it is possible to provide a vehicle seat having a structure that can reduce weight and reduce discomfort caused by vibrations transmitted to occupants, and a method for reducing vibrations therein. [Brief explanation of the drawings]

[0019] [Figure 1] 1A is a perspective view showing an example of the configuration of a frame of a vehicle seat, and FIG. 1B is a perspective view of a vehicle seat provided with a mesh upholstery. [Figure 2] 2 is a top view showing the configuration of a joint between a backrest portion and a seat frame of a vehicle seat. FIG. [Figure 3] 1A and 1B are an enlarged image and a schematic diagram of a portion of the resonator, showing an example of a resin structure made of a metamaterial and including a resonator; [Figure 4] 1 is a perspective view showing an example of a vehicle seat including a vibration reducing member made of a CFRP plate-shaped member. [Figure 5] FIG. 6 is an enlarged view of the seat portion of FIG. 5. [Figure 6] FIG. [Figure 7] 10A and 10B show simplified models used to verify the vibration suppression effect, where (A) shows the case of a spring and (B) shows the case of urethane. [Figure 8A] 10 is a graph showing an example of a vibration waveform used to verify the vibration suppression effect. [Figure 8B] 8B is a graph showing an example of a road simulation wave when the waveform shown in FIG. 8A is excited. [Figure 9A] 10 is a graph showing an example of an excitation waveform and an acceleration time history used to verify the vibration suppression effect. [Figure 9B] 10 is a graph showing an example of an acceleration frequency analysis obtained in verification of vibration suppression effect. [Figure 10] 10 is a table showing the numerical values obtained in the calculation and verification of the vibration suppression effect. [Figure 11] This is a 3D graph showing the vertical acceleration of each vehicle seat, illustrating the results of verification of the vibration suppression effect of the developed product and the commercially available product. [Figure 12] 10 is a table and graph showing the results of a sensory evaluation carried out as one of the verifications of the vibration suppression effect. [Figure 13] 1 is a table showing the results of a sensory evaluation of discomfort index. [Figure 14] FIG. 10 is a diagram showing a resin structure used in the calculation of the vibration suppression effect. [Figure 15] 10 is a table showing the results of vibration intensity amplitude of a sheet as a verification result when a resin structure is vibrated. [Figure 16] (A) A schematic diagram showing a simulated occupant and seat used in the calculation of vibration suppression effects, and (B) a schematic diagram showing the seat viewed from a different angle. [Figure 17] 10 is a table showing numerical values as verification results when a spherical simulated occupant model is in contact with the center of the seat surface. DETAILED DESCRIPTION OF THE INVENTION

[0020] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a vehicle seat according to the present invention will now be described in detail with reference to the drawings.

[0021] [Vehicle seats] The vehicle seat 1 is a seat for an occupant installed in a vehicle (not shown), and includes a headrest 10, a seat portion 20, and a backrest portion 30. The seat portion 20 includes a seat frame 32 and a vibration-reducing member (see FIG. 1). The vibration-reducing member is a member that reduces vibrations transmitted to an occupant in the vehicle seat 1 when the vehicle is traveling. Specific examples of vibration-reducing members that can perform this function are described below.

[0022] [Example of vibration reduction material (1)] One example of a component that can be used as a vibration-reducing component is a resin structure 22 made of a metamaterial. Metamaterials are artificially designed materials with properties not found in nature. Among these, metamaterials that are effective against sound and vibration are called mechanical metamaterials. The properties that can be achieved by such mechanical metamaterials include negative density, negative compressibility, negative refraction (achieved by simultaneously satisfying negative density and negative compressibility), a large refractive index, and anisotropic density. Furthermore, it is known that mechanical metamaterials have a forbidden frequency range, which is important for achieving high sound insulation and vibration damping. Mechanical metamaterials can be realized by coupling a resonator 22s that resonates at a specific frequency to a base material 22b. A forbidden frequency range is formed near the natural frequency of the resonator 22s, and frequencies within the forbidden frequency range cannot pass through the structure. This results in high sound insulation within a specific frequency range. However, it is known that the forbidden frequency range of mechanical metamaterials is narrow. In this embodiment, by using a resin structure 22 having such properties as a vibration-reducing member, the transmission of vibrations caused by road noise to the occupant's body when riding in a vehicle (particularly the transmission of vibrations in the range of 20 Hz to 50 Hz) is reduced, resulting in a vehicle seat 1 that is comfortable even when riding for a long time.

[0023] [Example of vibration reduction material (2)] Another example of a member that can be used as a vibration-reducing member is CFRP. By providing a plate-shaped member 24 made of such CFRP in the seat portion 20, it can function as a vibration-reducing member (see FIGS. 4 to 6). In this embodiment, the plate-shaped member 24 is provided with slits 24s extending in the width direction (left-right direction of the vehicle) to provide appropriate elasticity (in other words, springiness or flexibility) (see FIGS. 5 and 6). Instead of using a plate-shaped member 24 with slits 24s, multiple narrow and long (relatively long in length compared to width) CFRP leaf spring members may be combined to provide appropriate elasticity. In short, if the slits 24s are shallow grooves, the portions act as folds in the plate-shaped member 24, and if the slits 24s are complete slits, the portions act as boundaries between multiple plate-shaped members 24.

[0024] [Seat and backrest] The seat portion 20 includes the resin structure 22 or the plate-like member 24 as a vibration-reducing member, and may also include upholstery on its surface. In this embodiment, mesh upholstery 26, 34 is provided on the seat portion 20 and the backrest 30, respectively (see FIG. 1(B)). The mesh upholstery 34 is made of a mesh material, and its periphery is supported by the seat frame 32, forming a hammock-like structure in the central portion 30C of the backrest 30. In this embodiment, the backrest 30 does not include an elastomer material such as polyurethane that functions as a cushioning material in at least the central portion 30C or in any other portion. In other words, the backrest 30 of the vehicle seat 1 of this embodiment does not substantially contain a foam-like material that absorbs shock, and the mesh upholstery 34 is solely responsible for deforming the backrest 30 to absorb shock during a vehicle collision. The mesh upholstery 34 that performs this function may be a three-dimensional knitted fabric. Similarly, the seat portion 20 is not provided with an elastomer material such as polyurethane that functions as a cushioning material.

[0025] [Seat frame] The seat frame 32 is made of at least one of CFRP, UD material, and composite laminated resin material (see FIG. 1(A)). By making the seat frame 32 out of these materials instead of metal materials (i.e., by using resin), it is possible to reduce the weight of the seat frame 32 and, in turn, the vehicle seat 1 while maintaining the necessary rigidity. Specifically, for example, by using CFRP as the skeleton and arranging UD material as the outer layer, it is possible to use it as a frame instead of metal (see FIG. 2). Alternatively, for example, a combination of UD material and continuous fiber composite material is also suitable.

[0026] According to the vehicle seat 1 described above, vibrations transmitted to an occupant of the vehicle seat 1 during travel can be reduced by the vibration-reducing members (specifically, the resin structure 22 and the plate-like members 24), thereby reducing discomfort caused by the vibrations transmitted to the occupant. Furthermore, the seat frame 32 can be made of at least one of CFRP, UD material, and composite laminated resin material, thereby reducing the weight.

[0027] The above-described embodiment is one example of a preferred embodiment of the present invention, but the present invention is not limited to this embodiment and can be modified in various ways without departing from the spirit of the present invention. [Example]

[0028] In the vehicle seat 1 described above, the vibration suppression effect was verified by calculation in order to quantify the extent to which the vibration transmitted to the occupant of the vehicle seat 1 during travel is reduced by the vibration-reducing members (the resin structure 22 and the plate-like members 24). The results are described below as examples.

[0029] [Example 1] First, a model was created with a seat frame 32 and a seat surface (indicated by reference symbol 20a), with a simulated human body MP representing an occupant placed on the seat surface 20a. The analysis analyzed vibration transmission in the seat surface 20a, simulating the seated position of an occupant, for both cases where the seat surface 20a was a leaf spring (plate-shaped member 24) and where the seat surface 20a was made of urethane foam 300 (see FIG. 7). Because including a human body would require enormous calculation time, a simplified model of the vehicle seat 1 was adopted, focusing only on the seat portion 20. The leaf spring was tensioned between the seat frames 32 on both sides (see FIG. 7(A)), and the urethane foam 300, 24 mm thick, was placed in a virtual box bounded by the sides and bottom (see FIG. 7(B)). The simulated human body MP was an elliptical cylinder with a minor axis of 150 mm, a major axis of 300 mm, and a length of 305 mm, representing a human weighing 80 kg. In this model, with an occupant seated, vibrations equivalent to those from the ground were applied to the seat frame 32 to simulate driving. Two types of vibrations were applied to the seat frame 32: a 35 Hz sine wave (see Fig. 8A) and a road-simulated wave measured by an accelerometer attached to the floor of the vehicle (see Fig. 8B).

[0030] The results of analyzing the state when vibrations simulating road vibrations were applied were as follows (see FIGS. 9A and 9B). First, as shown in the time history of acceleration at the measurement point (the point where the simulated human body MP was placed at the center of the spring and urethane, as shown in FIG. 7), it was confirmed that the structure including the leaf spring (plate-shaped member 24) reduced vibrations to about one-quarter compared to the structure including urethane foam 300 (see FIG. 9A). Furthermore, analysis of the acceleration frequency during vibration confirmed that the structure including the leaf spring (plate-shaped member 24) was more effective at reducing vibrations than the structure including urethane foam 300, particularly in the frequency range that affects comfort (specifically, the 20 Hz to 50 Hz range) (see FIG. 9B).

[0031] Figure 10 shows the results of summarizing the specific materials, excitation conditions, predominant frequency of response acceleration, maximum excitation amplitude A [G], maximum response amplitude B [G], and reduction ratio for the structure including urethane foam 300 and the structure including leaf springs (plate-shaped members 24). The reduction ratio is the ratio (B / A) of the maximum response amplitude B to the maximum excitation amplitude A. These results confirmed that the structure including leaf springs (plate-shaped members 24) had a response amplitude of one-third or less of the excitation amplitude when excited with a sine wave and when excited with a road-simulated wave. On the other hand, it was confirmed that the structure including urethane foam 300 sometimes had an increased response amplitude in response to the road-simulated wave, and that the thickness was insufficient to sufficiently reduce vibration.

[0032] Next, a driving test was conducted using a variable drive simulator with three types of vehicle seats 1. The three types of vehicle seats 1 were (1) development model A, (2) commercial model SA (in which the existing upholstery material was replaced with a 3D knitted fabric upholstery material), and (3) commercial model SH (see Figure 11). The driving test was conducted with the participation of 12 monitors on a course incorporating five vibration levels within an acceleration range of 0.2 to 1.0 m / s2, each of which was repeated five times. The evaluation items were vibration intensity, sensory feedback, and heart rate. The sensory evaluation was conducted by having the monitors rate their discomfort level on a five-point scale for each vibration. Acceleration measurements were conducted using accelerometers installed on the seat surface 20a and floor. The acceleration data (see Figure 11) confirmed that vertical acceleration (vibration) was suppressed.

[0033] The sensory evaluation was carried out by assessing the perceived vibration sensation when the vibration level was changed from 1 to 5 (see Figures 12 and 13). If the perceived vibration level was lower than the actual level (in other words, if the vibration level reported by the subject was lower than the actual vibration level), it was determined that the vibration had been reduced. The results of the sensory evaluation confirmed that developed product A tended to be slightly less uncomfortable (comfortable). The average of all vibration ratings from each monitor also showed that developed product A tended to be slightly less uncomfortable.

[0034] [Example 2] Resin structure 22 equipped with resonators 22s was used as a vibration-reducing member to verify its vibration suppression effect. Resin structure 22, the unit structure shown in Fig. 3, was placed in a resin sheet of 300 mm x 375 mm, and vibrations were applied to both ends of the sheet with an excitation amplitude of 1 G, and the response acceleration amplitude was measured at six positions on the sheet (positions indicated by symbols (1) to (6) in Fig. 14).

[0035] Figure 15 shows the response acceleration amplitude results for the seat in the above model. It was confirmed that by using resin structure 22 with resonators 22s as unit structures, it is possible to achieve the target reduction ratio (1 / 3 damping) for amplitudes between 20 Hz and 50 Hz (the dominant frequency of the brain). It is expected that similar results will be obtained when this structure is used as a seat.

[0036] [Example 3] The vibration suppression effect was also verified by calculation for a vehicle seat 1 in which a resin structure 22 equipped with resonators 22s was used as a vibration-reducing member and overlapped with a leaf spring to form the seat surface. Here, a simplified model of the vehicle seat 1 was used, with only the seat surface 20 included, and a resin structure 22 made of metamaterial was placed on top of the leaf spring between CFRP seat frames 32 (height 60 mm) on both sides (see Figures 16(A) and 16(B)). A spherical human body weighing 80 kg was used as the simulated human body MP. Here, the center of the seat surface 20a was set to be the contact point with the spherical simulated human body MP.

[0037] Excitation conditions, dominant frequency of response acceleration, excitation amplitude C [mm / s 2 ], maximum response amplitude D [mm / s 2 ], reduction ratio, target reduction ratio, and judgment results are summarized in Figure 17. The reduction ratio is the ratio (D / C) of the maximum response amplitude D to the excitation amplitude C. From these results, it was confirmed that, although a human body simulation model was not used, it was possible to achieve the target reduction ratio (1 / 3 attenuation) for amplitudes of 20 Hz to 50 Hz (the dominant frequency of the brain) with the same weight. [Industrial Applicability]

[0038] The present invention is suitable for use in a vehicle seat installed in a vehicle. [Explanation of symbols]

[0039] 1...Vehicle seat 10...Headrest 20... Seat area 20a…seat 22...Resin structure (vibration reduction member) 22b…Base material 22s…Resonator 24...Plate-shaped member (vibration reduction member) 24s...Slit 26...Mesh upholstery (mesh material upholstery) 30...Backrest 30C…Central part 32...Seat frame 34...Mesh upholstery (mesh material upholstery) 300...Urethane foam A: Maximum excitation amplitude B…Maximum response amplitude C…Excitation amplitude D…pp amplitude MP…Simulated human body

Claims

1. A vehicle seat to be installed in a vehicle, a vibration reducing member that reduces vibrations transmitted to an occupant of the vehicle seat during driving; a seat frame made of at least one of CFRP, UD material, and composite laminated resin material; a seat having The vehicle seat, wherein the vibration-reducing member is made of a resin structure and / or CFRP.

2. The vehicle seat according to claim 1 , wherein the vibration-reducing member is made of a resin structure.

3. The vehicle seat according to claim 2 , wherein the resin structure is a structure made of a metamaterial.

4. The vehicle seat according to claim 3 , wherein the structure made of the metamaterial includes a resonator.

5. 2. The vehicle seat according to claim 1, wherein the vibration reducing member is made of CFRP.

6. The vehicle seat according to claim 5 , wherein the vibration reducing member includes a plate-shaped member made of CFRP.

7. The vehicle seat according to claim 6, wherein the plate-shaped member includes a long CFRP leaf spring member.

8. 8. The vehicle seat according to claim 1, wherein the vibration reducing member is a member that reduces vibrations in a range of at least 20 Hz to 50 Hz.

9. The vehicle seat according to claim 1 , wherein the seat portion includes an upholstery made of a mesh material and does not include a urethane-type cushioning material.

10. A method for reducing vibrations of a vehicle seat installed in a vehicle, comprising: The seat portion of the vehicle seat is a vibration reducing member that reduces vibrations transmitted to an occupant of the vehicle seat during driving; a seat frame made of at least one of CFRP, UD material, and composite laminated resin material; a vibration reducing method for reducing vibration transmitted to an occupant by the vibration reducing member and the seat frame by providing the vibration reducing member, A vibration reduction method, wherein the vibration reduction member is made of a resin structure and / or CFRP.

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