Sound Absorbing Board for Electric Vehicles

Abstract

To provide a sound absorbing board for an electric vehicle that improves sound absorption performance in a low frequency range of 1,000 Hz and a high frequency range of 5,000 Hz and above, which are generated mainly in the electric vehicle.SOLUTION: In a sound-absorbing board, a sound absorption performance with respect to noise in a high frequency band as well as a low frequency band is improved by using multi-layer sound absorption characteristics that change a frequency band capable of absorbing sound while passing through each honeycomb structure, by composing a honeycomb structure 200, a glass fiber mat 300, and polyurethane 400 on both sides with reference to a perforated plate 100 having sound absorption holes 110, respectively, and forming sound absorption holes 410 in at least one of the glass fiber mat and the polyurethane arranged on both sides of the honeycomb structure so as to penetrate one by one corresponding to each cell. In particular, the sound absorption band of a desired frequency can be easily adjusted by fabricating different diameters of the sound absorption holes that are formed to pass through the honeycomb structures arranged on both sides with reference to the perforated plate.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a sound-absorbing board for electric vehicles. More specifically, after arranging honeycomb structures on both sides centering on a perforated plate, glass fiber mats and polyurethanes are respectively coated on the outside and integrally formed. Then, among the glass fiber mats and polyurethanes arranged on both sides based on the perforated plate so as to communicate with cells forming the honeycomb structure, sound absorption holes are formed in at least one of them, so that different frequency bands can be sound-absorbed through each honeycomb structure, and the sound absorption performance in the low-frequency band (1,000 Hz) and high-frequency band (5,000 Hz or more) mainly generated in electric vehicles is improved.

Background Art

[0002] Generally, in automobiles, sound-absorbing panels are used everywhere to reduce the noise generated from components of the automobile such as the engine and transmission during driving and the noise generated from the lower part of the automobile, so as to maintain a comfortable driving environment. At this time, as the sound-absorbing panel, a board-shaped one such as the sound-absorbing panel of the dashboard D or the hood H as shown in FIG. 1 can be directly used, or it can also be manufactured and used in a multilayer structure together with other layers such as the luggage board B and the luggage cover lining C. Such sound-absorbing boards are manufactured by various methods as in Patent Documents 1 to 3.

[0003] It relates to a highly sound-absorbing ceiling panel for vehicles. More specifically, it includes a polyurethane foam layer, reinforcing layers formed on both side surfaces of the polyurethane foam layer, a felt layer formed on the upper surface of the polyurethane foam layer on which the reinforcing layer is formed, a film layer formed on the lower surface of the polyurethane foam layer on which the reinforcing layer is formed, and a non-woven fabric layer formed on the lower surface of the film layer. In addition, it may also include a polyurethane foam layer, reinforcing layers formed on both side surfaces of the polyurethane foam layer, and felt layers formed on both side surfaces of the polyurethane foam layer on which the reinforcing layer is formed.

[0004] In a method for producing a polyurethane foam, 3 to 10% by weight of a low molecular weight polyol having a number average molecular weight of 1,000 or less is mixed with 90 to 97% by weight of a high molecular weight polyol having a number average molecular weight of 6,500 or more to form a polyol, and a resin premix composed of diethanolamine, a foam stabilizer, a urethane catalyst, and a cell opener, and 15 to 30% by weight of monomeric MDI, 2.5 to 10% by weight of modified MDI, and 0.5 to 10% by weight of TDI are mixed and reacted with 50 to 82% by weight of polymeric MDI to obtain a modified polyisocyanate containing 25 to 40% by weight of isocyanate groups, and a urethane reaction is carried out at an isocyanate index of 0.5 to 2.0 to produce a polyurethane foam for an automotive floor mat sound-absorbing material. The polyurethane foam produced by such a method has an effect of maintaining excellent sound absorption and durability while having a low density and being lightweight. 3 It has the effect of being able to maintain excellent sound absorption and durability while having a low density and being lightweight.

[0005] The present invention relates to a sound-absorbing structure for a vehicle dash panel. In particular, in a sound-absorbing structure for a vehicle dash panel in which a wire is fixed to a dash panel that divides an engine room and a vehicle interior, fixing protrusions are formed on the wire so as to protrude in a direction facing the dash panel, and fixing grooves to which the fixing protrusions are coupled are formed on the dash panel. Since no separate fixing device such as a protector is required to fix the wire to the dash panel, the NVH performance is enhanced and the product cost is reduced.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0007] On the other hand, recently, with the popularization of electric vehicles, by applying the sound-absorbing board used in conventional vehicles to electric vehicles, referring to FIGS. 2 and 3, the following problems occur. FIG. 2 shows a graph of measuring the rear seat noise of an electric vehicle, where the vertical axis represents rpm and the horizontal axis represents frequency (Hz). In FIG. 3, the horizontal axis represents rpm and the vertical axis represents noise (dB[A]).

[0008] Comparing the noise results measured at the rear seat of an electric vehicle in this way, as shown in FIGS. 2 and 3, it can be seen that the noise levels are high at the 24th order 3,000 rpm and the 48th order 7,800 rpm. When converting the noise level at this time into frequency (Hz), it is in a state of about 1,200 Hz and 6,200 Hz. In particular, although the noise level at 6,200 Hz is lower, in an electric vehicle, there is no engine noise, and high-frequency noise is a more serious problem in electric vehicles. Furthermore, in most electric vehicles, by using the sound-absorbing board of a conventional vehicle, a certain degree of sound-absorbing effect can be obtained in the low band (about 1,200 Hz), but in the high band (6,200 Hz or more), no sound-absorbing effect can be expected.

[0009] The present invention takes such points into consideration, arranges honeycomb structures on both sides with a perforated plate as a reference, and applies a glass fiber mat and polyurethane to both sides thereof respectively. Then, sound-absorbing holes are formed in at least one of the glass fiber mat and polyurethane arranged on both sides with the perforated plate as a reference, and they are configured to penetrate one by one corresponding to each cell. Therefore, an object of the present invention is to provide a sound-absorbing board for electric vehicles that can improve the sound-absorbing performance for noise in both low-frequency and high-frequency bands by using multi-layer sound-absorbing characteristics that change the frequency band that can be sound-absorbed while passing through each honeycomb structure.

[0010] In particular, the present invention can easily adjust the sound absorption band of a desired frequency by manufacturing the diameters of sound absorption holes formed so as to communicate with honeycomb structures arranged on both sides with reference to a perforated plate, and can improve the sound absorption performance in the low frequency band of 1,000 Hz and the high frequency band of 5,000 Hz or more, which are mainly generated in electric vehicles. Another object is to provide a sound absorption board for electric vehicles.

[0011] Further, the present invention provides a sound absorption board for electric vehicles that can improve the sound absorption performance in the frequency band mainly generated in electric vehicles and create a comfortable indoor environment by using such a sound absorption board for electric vehicles as a sound absorption board for a dash panel, a sound absorption board for a rear seat back panel, a sound absorption board for a luggage board, and a sound absorption board for a luggage cover. Another object is also to provide a sound absorption board for electric vehicles.

Means for Solving the Problems

[0012] A sound absorption board for an electric vehicle according to the present invention for achieving such an object includes a perforated plate 100 having a plurality of sound absorption holes 110 formed on one side, and two honeycomb structures 200 that are respectively disposed in close contact with both side surfaces with reference to the perforated plate 100, and the distance between the opposing surfaces in the cell is 5 to 15 mm. A glass fiber mat 300 having a surface density of 150 to 1,000 g / m provided on the surface of each honeycomb structure 200 exposed to the outside, and a polyurethane 400 applied to the surface of each glass fiber mat 300 exposed to the outside with a surface density of 150 to 1,000 g / m. Among the glass fiber mat 300 and the polyurethane 400 configured on both sides with reference to the perforated plate 100, a plurality of sound absorption holes 410 are formed through at least one of the glass fiber mat 300 and the polyurethane 400 configured therein, and the sound absorption holes 410 are formed by communicating with each cell constituting the honeycomb structure 200 one by one. 2 In particular, the honeycomb structure 200 is characterized by being made of paper, aluminum, or synthetic resin. 2 In particular, the honeycomb structure 200 is characterized by being made of paper, aluminum, or synthetic resin.

[0013] In particular, the honeycomb structure 200 is characterized by being made of paper, aluminum, or synthetic resin.

[0014] In addition, the sound absorption holes 110 formed in the perforated plate 100 and the sound absorption holes 410 formed in the polyurethane 400 are each formed with a diameter of 0.2 to 4 mm, and the diameters of the sound absorption holes 110 and 410 are formed to be the same or different.

[0015] And the sound absorption board for the electric vehicle is formed so that sound absorption performance can be obtained at 1,000 Hz in the low frequency band and 5,000 Hz in the high frequency band.

[0016] Finally, the sound absorption board for the electric vehicle is characterized in that it is a sound absorption board for a dash panel, a sound absorption board for a rear seat back panel, a sound absorption board for a luggage board, or a sound absorption board for a luggage cover.

Effects of the Invention

[0017] The sound absorption board for the electric vehicle according to the present invention has the following effects.

[0018] (1) By arranging honeycomb structures on both sides with reference to the perforated plate and integrally configuring them, applying a glass fiber mat and polyurethane to the outside of each honeycomb structure, and then forming sound absorption holes penetrating through the polyurethane and the glass fiber mat on either side of the honeycomb structure so as to communicate with each cell, the sound absorption performance of each honeycomb structure can be obtained, and the sound absorption performance of the sound absorption board can be improved.

[0019] (2) At this time, since the sound absorption performance obtained from each honeycomb structure varies depending on the diameter of the sound absorption holes, the diameters of the sound absorption holes formed in the two honeycomb structures are manufactured to be different so as to obtain sound absorption performance in other frequency bands.

[0020] (3) By manufacturing it so as to obtain sound absorption performance for frequencies in the 1,000 Hz band and high-frequency bands of 5,000 Hz and above, which mainly occur in electric vehicles, the sound absorption performance in electric vehicles can be further improved.

[0021] (4) On the other hand, since such a sound absorption board can replace the sound absorption material, it can be used as a sound absorption board for a dash panel, a sound absorption board for a rear seat back panel, a sound absorption board for a luggage board, or a sound absorption board for a luggage cover, which are required in electric vehicles, and the sound absorption performance can be improved while being used in various ways.

Brief Description of the Drawings

[0022]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Best Mode for Carrying Out the Invention

[0023] Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the accompanying drawings. First, the terms or words used in this specification and the claims should not be construed as being limited to their ordinary or dictionary meanings. The inventor should interpret them as meanings and concepts consistent with the technical idea of the present invention in accordance with the principle that the concept of the terms can be appropriately defined in order to explain the invention in the best way.

[0024] Therefore, it should be understood that the embodiments described in this specification and the configurations shown in the drawings are only the most preferred embodiments of the present invention and do not represent all of the technical ideas of the present invention. There may be various equivalents and modifications that can replace them at the time of this application.

[0025] [Structure of Sound Absorbing Board for Electric Vehicles] The sound absorption board for an electric vehicle according to the present invention includes, as shown in FIGS. 4 to 7, perforated plates 100, two honeycomb structures 200, a glass fiber mat 300 and a polyurethane 400 formed outside each honeycomb structure 200.

[0026] In particular, among the glass fiber mat 300 and the polyurethane 400 respectively formed on both sides with respect to the perforated plate 100, one sound absorption hole 410 is formed to penetrate each cell constituting the honeycomb structure 200 in at least one of the glass fiber mat 300 and the polyurethane 400. By configuring in this way, resonance actions can be respectively caused by the two honeycomb structures 200, and the sound absorption performance can be further enhanced.

[0027] At this time, the sound absorption holes 410 are formed with different diameters so that the two honeycomb structures 200 can absorb sound in different frequency bands, thereby improving the sound absorption performance in the low-frequency range of 1,000 Hz and the high-frequency range of 5,000 Hz or more generated by a normal electric vehicle, and creating a comfortable driving environment.

[0028] In addition, the sound absorption board for an electric vehicle according to the present invention can replace sound absorption materials such as a sound absorption board for a dash panel, a sound absorption board for a rear seat back panel, a sound absorption board for a luggage board, and a sound absorption board for a luggage cover, and can enhance the sound absorption performance throughout the electric vehicle.

[0029] Hereinafter, such a configuration will be described in more detail with reference to the accompanying drawings as follows.

[0030] 1. Perforated Plate As shown in FIG. 4, the perforated plate 100 has sound absorption holes 110 penetrating through one side. At this time, the sound absorption holes 110 are formed so as to be located one by one for each hexagonal columnar cell that constitutes the honeycomb structure 200 described later and is provided in close contact with each of the two side surfaces of the perforated plate 100.

[0031] In a preferred embodiment of the present invention, when the sound absorption holes 110 are integrally formed with the perforated plate 100 and the honeycomb structure 200 facing each other in this way, it is preferable to form them so as to be located at the center of the cell. This is because the sound absorption effect is performed in the cell while noise enters and exits the cells located on both sides of the sound absorption holes 110, so that the sound absorption performance can be doubled. Such sound absorption holes 110 will have a diameter d formed to be 0.2 to 4 mm, but can also be manufactured to be the same as or different from the diameters of other sound absorption holes 410 described later.

[0032] On the one hand, in a preferred embodiment of the present invention, the perforated plate 100 can be made of any material as long as it can perform a sound insulation function between the two honeycomb structures 200 and an absorption function through the absorption holes 110. Such materials include, by way of example, paper, aluminum, or synthetic resin.

[0033] As shown in FIG. 4, the honeycomb structures 200 are integrally formed on both side surfaces of the perforated plate 100 thus formed. At this time, the perforated plate 100 may be inserted between the two honeycomb structures 200 described below in a state where an adhesive or the like is laminated and integrally coated on the surface, and heat and pressure are applied to integrally mold them.

[0034] 2. Honeycomb Structure As shown in FIGS. 4 and 5, the honeycomb structure 200 is made by a normal technique so as to be in a form in which hollow cells formed in a regular hexagonal columnar shape are connected without gaps. At this time, the honeycomb structure 200 is preferably manufactured so as to be lightweight and have sufficient structural rigidity while reducing the weight of the sound absorption board. Therefore, it is most preferable to use the honeycomb structure 200 in which the distance L between the opposing surfaces is 5 to 15 mm.

[0035] Also, in a preferred embodiment of the present invention, the honeycomb structure 200 can be made of any material as long as it is lightweight and can reinforce the structural rigidity. Such materials include, by way of example, paper, aluminum, and synthetic resin.

[0036] As shown in FIG. 4, such a honeycomb structure 200 is preferably formed by attaching one each to both sides with reference to the perforated plate 100 described above and integrally attaching them using a laminate technique.

[0037] 3. Glass Fiber Mat As shown in Fig. 4, the glass fiber mat 300 is provided in close contact with the surface of each of the honeycomb structures 200 exposed to the outside. These glass fiber mats 300 not only reinforce the rigidity of the sound-absorbing board according to the present invention, but also improve the sound-absorbing performance of the sound-absorbing board by using the sound-absorbing performance of the glass fiber itself.

[0038] These glass fiber mats 300 do not become too heavy in their own weight, and it is preferable to use those having a surface density of 150 to 1,000 g / m 2 to obtain rigidity reinforcement and sound-absorbing performance.

[0039] The glass fiber mat 300 configured in this way allows the polyurethane 400 described later applied thereon to penetrate and adhere integrally to the honeycomb structure 200. And, sound-absorbing holes 410 are formed in the glass fiber mat 300 in a state of overlapping with the polyurethane 400 described later, and these sound-absorbing holes 410 are formed so as to communicate one by one for each cell constituting the honeycomb structure 200 described above.

[0040] 4. Polyurethane As shown in Fig. 4, the polyurethane 400 is formed by applying it to the surface of each of the glass fiber mats 300 exposed to the outside. At this time, while the polyurethane 400 penetrates into the glass fiber mat 300 and adheres to the cell edges of the honeycomb structure 200 to function as an adhesive, it finishes the entrance portion of the cells forming the honeycomb structure 200 so that each cell forms an independent air layer.

[0041] In a preferred embodiment of the present invention, the polyurethane 400 is applied with a surface density of 150 to 1,000 g / m 2 so that while finishing the cell entrance portion of the honeycomb structure 200, it is preferably configured to firmly adhere the glass fiber mat 300.

[0042] On the one hand, in a preferred embodiment of the present invention, it is preferable that the polyurethane 400 is configured such that sound absorption holes 410 are formed therethrough as shown in FIGS. 4 and 5. This sound absorption hole 410 is for allowing noise to enter the cells constituting the honeycomb structure 200 from the outside of the sound absorption board according to the present invention so that the sound absorption effect can be achieved.

[0043] Also, in a preferred embodiment of the present invention, it is preferable that one sound absorption hole 410 is formed through each cell constituting the honeycomb structure 200 described above. Most preferably, the sound absorption hole 410 is formed so as to be located at the center of the cell. At this time, the sound absorption hole 410 is preferably formed by penetrating the glass fiber mat 300 together with the polyurethane 400.

[0044] And the diameter d of the sound absorption hole 410 is formed to be 0.2 to 4 mm, but it can also be manufactured to be the same as or different from the diameter of the sound absorption hole 110 described above. Further, the sound absorption holes 410 formed in each honeycomb structure 200 can be configured to have the same diameter so as to absorb frequencies in the same band. However, by configuring them to have different diameters so as to absorb frequencies in other bands, it is most preferable to configure them to be able to absorb frequencies in both the low-frequency and high-frequency bands simultaneously.

[0045] Finally, the sound absorption hole 410 is shown by way of example as being formed in both the glass fiber mat 300 and the polyurethane 400 respectively formed on both sides with reference to the perforated plate 100 as shown in FIG. 4(a). However, the sound absorption hole 410 can penetrate and be formed only in the glass fiber mat 300 and the polyurethane 400 on either one side with reference to the perforated plate 100 as shown in FIG. 4(c). When formed in this way, it is preferable to provide the sound absorption board such that the sound absorption hole 410 is located on the noise source side so that the noise can be effectively absorbed within the cell.

[0046] (Sound Absorbing Characteristics of Sound Absorbing Board) Regarding the sound absorption characteristics according to the present invention, referring to FIGS. 6 and 7, it is as follows. The sound absorption board according to the present invention, as shown in FIG. 4(a), is a multilayer structure in which a honeycomb structure 200 that forms other sound absorption holes 410 based on a perforated plate 100 with sound absorption holes 110 formed therein and constitutes a space is integrated, and sound absorption is performed. FIG. 6 is a cross-sectional view of the multilayer structure for explaining the sound absorption characteristics of the multilayer structure of FIG. 4. When calculating the sound absorption characteristics of the multilayer structure using this, it can be expressed by the following Equations 1 to 3.

[0047] Here, in the multilayer structure arranged in a panel shape, the panel layer can be expressed by a P matrix represented by the following Equation 1. Here, the symbol "ζ" indicates the specific acoustic impedance.

[0048]

Equation

[0049] And the cavity between the panels in the multilayer structure, that is, the honeycomb cell, is represented by an S matrix represented by the following Equation 2. At this time, the symbol "k" represents the wave number (rad / m), "l" represents the thickness of the honeycomb, "j" represents the imaginary part of the impedance, and "ρ0" represents the air density (kg / m 3 ), and "c0" represents the speed of sound, respectively.

[0050]

Equation

[0051] On the other hand, the T matrix representing the total sound absorption rate of the multilayer structure using such a P matrix and S matrix can be expressed as follows in Equation 3.

[0052]

Equation

[0053] The graph showing the sound absorption rates obtained for a comparative example consisting of a single perforated layer (Fig. 7 (upper)) and an example consisting of multiple perforated layers (Fig. 7 (lower)) with respect to the change in frequency (Hz) for the sound absorption rate expressed in this way is as shown in Fig. 7 below. In Fig. 7, the horizontal axis represents the frequency and the vertical axis represents the sound absorption rate.

[0054] As a result, in the case of the comparative example with a single-layer structure as shown in Fig. 7 (upper), there is a sound absorption effect only at one peak (low-frequency band), and even if the position of the sound absorption holes is adjusted, only a slight sound absorption adjustment is performed in the low-frequency band, and no sound absorption performance is obtained in the high-frequency band. However, in the example, as shown in Fig. 7 (lower), it can be seen that peaks occur in both the low-frequency band and the high-frequency band, and it can be understood that the sound absorption performance in both the low-frequency band and the high-frequency band can be improved by adjusting the sound absorption holes.

[0055] In particular, by adjusting the position and number of the sound absorption holes, the interval between the sound absorption holes, etc., the sound absorption performance can be adjusted so that the sound absorption rate changes from the black line to the red line in Fig. 7.

[0056] As shown in Fig. 7 (lower), when configured in a multi-layer structure, sound absorption performance can be obtained in the low-frequency band and the high-frequency band respectively using the diameter of the sound absorption holes, etc. However, the sound absorption board according to the preferred embodiment of the present invention, as shown in Figs. 2 and 3, in the frequency band generated when an electric vehicle is running, it is most preferable to manufacture and use it so that sound absorption performance can be obtained in the low-frequency band of 1,000 Hz, which is the low-frequency band that the driver and passengers can mainly feel as noise, and in the high-frequency region of 5,000 Hz or more.

[0057] Finally, the sound absorption board for an electric vehicle according to the present invention can be applied to the sound absorption board for a dash panel, the sound absorption board for a rear seat back panel, the sound absorption board for a luggage board, and the sound absorption board for a luggage cover, and can be used only with the sound absorption board itself according to the present invention, or can be used as a sound absorption material in a multi-layer structure, so that the sound absorption performance can be further improved throughout the electric vehicle.

Explanation of Reference Numerals

[0058] 100: Perforated plate 110: Sound-absorbing hole 200: Honeycomb structure 300: Glass fiber mat 400: Polyurethane

Claims

1. A perforated plate (100) having a plurality of sound absorption holes (110) formed on one side, Two honeycomb structures (200) that are arranged in close contact with both side surfaces with reference to the perforated plate (100), and the distance between the opposing surfaces in the cell is 5 to 15 mm, A glass fiber mat (300) having a surface density of 150 to 1,000 g / m provided on a surface of each of the honeycomb structures (200) exposed to the outside ２ and The polyurethane (400) is applied to the surface exposed to the outside with each of the glass fiber mats (300) at a surface density of 150 to 1,000 g / m ２ , and includes, The glass fiber mat (300) and the polyurethane (400) configured on both sides with reference to the perforated plate (100) have a plurality of sound absorption holes (410) penetratingly formed on each of the two sides. Among the two sides, the diameters of the sound absorption holes (410) are different between one side and the other side, The sound absorption holes (410) are each formed to communicate with one cell constituting the honeycomb structure (200). A sound absorption board for an electric vehicle, characterized in that.

2. The honeycomb structure (200) is made of paper, aluminum, or synthetic resin. The sound absorption board for an electric vehicle according to claim 1, characterized in that.

3. The sound absorption holes (110) formed in the perforated plate (100) and the sound absorption holes (410) formed in the polyurethane (400) are each formed with a diameter of 0.2 to 4 mm, Each of the sound absorption holes (110, 410) is formed with the same or different diameters. The sound absorption board for an electric vehicle according to claim 1, characterized in that.

4. The sound absorption board for an electric vehicle is formed so as to obtain sound absorption performance at 1,000 Hz in the low frequency band and 5,000 Hz in the high frequency band. The sound absorption board for an electric vehicle according to any one of claims 1 to 3, characterized in that.

5. The sound absorption board for an electric vehicle is a sound absorption board for a dash panel, a sound absorption board for a rear seat back panel, a sound absorption board for a luggage board, or a sound absorption board for a luggage cover. The sound absorption board for an electric vehicle according to claim 4, characterized in that.

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