Engine room bulkhead for electric vehicles

Abstract

The present invention relates to an engine room bulkhead for an electric vehicle comprising a foamed layer formed by mixing a foaming agent into a polymer resin composition composed of polypropylene, glass fiber, and inorganic additives and foaming it, and a sound-absorbing material formed on one surface of the foamed layer.

Description

Technology Field

[0001] The present invention relates to an engine room bulkhead for an electric vehicle. Background Technology

[0002] A vehicle engine compartment bulkhead serves to effectively disperse the impact force from a vehicle collision to panels connected through bulkhead members, thereby preventing components installed in the engine compartment (e.g., battery, brake booster, engine, transmission, etc.) from intruding into the vehicle's interior, as well as blocking vibrations or noise generated from those components (especially the engine and transmission) from being transmitted into the vehicle's interior through the dashboard.

[0003] Prior art regarding the above-mentioned engine room bulkhead is disclosed in Korean Patent Registration No. 10-0534428, "Structure of a bulkhead in an engine room," wherein the bulkhead member described in the above-mentioned prior art forms a first joint that is joined to a wheel apron panel at the front and lower portions, forms a second joint that is joined to a dash lower panel at the rear portion, and forms a third joint that is joined to a front cowl panel at the upper portion of the rear portion, and is installed in the engine room of a vehicle.

[0004] The bulkhead member described in the prior art above is configured as a double bulkhead structure by connecting the wheel apron panel, the dash lower panel, and the front cowl panel separately, thereby preventing parts such as the battery, brake booster, engine, and transmission installed in the engine room from entering the interior during a vehicle collision, as well as preventing noise from entering the interior.

[0005] However, conventional vehicle engine compartment bulkheads are manufactured by injection molding synthetic resin, which has the problem of reduced sound insulation performance compared to general vehicle interior materials and lowered fuel efficiency due to their excessive weight. Prior art literature

[0006] Republic of Korea Registered Patent No. 10-2094826 (Published on March 31, 2020) The problem to be solved

[0007] The problem that the present invention aims to solve is to provide an engine room bulkhead for an electric vehicle that not only has excellent sound insulation performance but also reduces weight to improve fuel efficiency. means of solving the problem

[0008] The present invention provides, in one embodiment, an engine room bulkhead for an electric vehicle comprising a foamed layer formed by mixing a foaming agent into a polymer resin composition composed of polypropylene, glass fiber, and an inorganic additive and foaming it, and a sound-absorbing material formed on one surface of the foamed layer.

[0009] In addition, the polymer resin composition may include 45 to 65 weight% polypropylene, 20 to 30 weight% glass fiber, and 15 to 25 weight% inorganic additives.

[0010] In addition, the foam layer can be formed by mixing 1 to 5 weight percent based on 100 weight percent of the polymer resin composition and foaming.

[0011] In addition, the inorganic additive may be barium sulfate (BaSO4).

[0012] In addition, the blowing agent may be azodicarbonamide.

[0013] In addition, the sound-absorbing material may be composed of a first nonwoven fabric layer made of a polyester resin, a foam layer formed on one side of the first nonwoven fabric layer, and a second nonwoven fabric layer formed on one side of the foam layer.

[0014] In addition, the foam layer may have an average thickness of 1.5 to 2 mm.

[0015] In addition, the foam layer can have an average weight of 2.2 to 2.3 kg.

[0016] In addition, the engine room bulkhead for electric vehicles may have a power-based noise reduction of 62.4 to 65.2 dB at a frequency in the 1 / 3 Octave band of 0.4 to 6.3 kHz. Effects of the invention

[0017] The bulkhead for an electric vehicle according to the present invention not only exhibits superior sound insulation performance compared to conventional bulkheads, but also has the effect of improving the vehicle's fuel efficiency due to reduced weight. Brief explanation of the drawing

[0018] Figures 1 (a) and 1 (b) are images showing an engine room bulkhead manufactured according to Example 1. Figures 2 (a) and 2 (b) show the results of analyzing the sound insulation performance of engine room bulkheads manufactured according to Example 1, Example 2, and Comparative Example. Specific details for implementing the invention

[0019] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings so that those skilled in the art can easily implement the present invention. However, the present invention may be implemented in various different embodiments and is not limited to the embodiments described herein. Throughout the specification, similar parts are denoted by the same reference numerals.

[0021] The present invention provides, in one embodiment, an engine room bulkhead for an electric vehicle comprising a foam layer and a sound-absorbing material formed on one surface of the foam layer.

[0022] Specifically, the foam layer is formed by mixing a foaming agent into a polymer resin composition consisting of polypropylene, glass fibers, and inorganic additives, and then foaming it.

[0023] The polymer resin composition may contain 45 to 65 weight% of polypropylene, specifically 50 to 60 weight%, and specifically 55 weight%.

[0024] If the polypropylene content is less than 45 weight%, there is a problem with reduced moldability and processability, and if it exceeds 65 weight%, the desired foaming rate cannot be reached, so the sound absorption performance of the final product is reduced and the weight may increase relatively.

[0025] Polypropylene may have a melt index of 1 to 100 g / l / l / min measured at 230°C and a load of 216 kg, and specifically, the MI may be 10 to 50 g / l / l / min.

[0026] Polypropylene can have an appropriate range of melt index selected by considering both the foaming rate and mechanical properties, and is not limited thereto.

[0027] The polymer resin composition may contain 20 to 30 weight% of glass fiber, specifically 22 to 28 weight%, and more specifically 25 weight%.

[0028] If the glass fiber content is less than 20 weight%, impact resistance and heat resistance cannot be improved, and if it exceeds 30 weight%, workability is reduced and weight may increase.

[0029] Glass fibers can have a length of 5 to 20 mm. If the length of the glass fiber is less than 5 mm, it can degrade the mechanical properties of the final product, and if the length of the glass fiber exceeds 20 mm, there is a problem of reduced productivity and reduced workability of the final product.

[0030] Glass fiber is a non-combustible material that improves durability, strength, etc., as well as provides fire resistance. The types of glass fiber include E-GLASS and G-GLASS, but the type is not limited, and considering mechanical properties and fire resistance, it may be a glass fiber in the form of a roving cross.

[0031] The polymer resin composition may contain 15 to 25 weight% of an inorganic additive, specifically 18 to 22 weight%, and more specifically 20 weight%.

[0032] If the content of inorganic additives is less than 15 weight%, the effect of improving impact resistance and stiffness upon addition is not achieved, and if the content of inorganic additives exceeds 25 weight%, the weight of the final product may increase and workability may decrease.

[0033] The inorganic additive may be one or more selected from the group consisting of talc, calcium carbonate, barium sulfate, glass bubbles, and glass beads, specifically, it may be barium sulfate which has an excellent effect of improving impact resistance and stiffness, and more specifically, it may be barium sulfate having a specific gravity of 1.34 to 1.35.

[0034] In addition, barium sulfate can have a particle size of 0.1 to 100 μm, specifically a particle size of 10 to 50 μm, and more specifically a particle size of 30 μm.

[0035] In summary, the polymer resin composition, which is the main raw material for forming the foam layer, comprises 45 to 65 weight% polypropylene, 20 to 30 weight% glass fiber, and 15 to 25 weight% inorganic additives. For example, the polymer resin may comprise 65 weight% polypropylene, 25 weight% glass fiber, and 20 weight% barium sulfate. The polymer resin composition can be prepared by mixing the components within the aforementioned ranges, or it can be purchased and used from the market.

[0036] A foamed layer can be formed by mixing a foaming agent into the aforementioned polymer resin composition and foaming. Specifically, the foamed layer can be formed by mixing 1 to 5 weight percent of a foaming agent based on 100 weight percent of the polymer resin composition and foaming, and specifically, by mixing 2 to 3 weight percent, and more specifically 3 weight percent and foaming.

[0037] If the content of the foaming agent is less than 1 weight%, the foaming performance is reduced due to the low content of the foaming agent, and the lightweighting effect cannot be achieved. If the content of the foaming agent exceeds 5 weight%, the amount of foaming agent with low specific gravity is high, which can reduce the mechanical properties of the final product.

[0038] The blowing agent may be azodicarbonamide, for example, commercially available brand name Celegoene ® , Tracel ® , Hydrocerol ® Or it may be a mixture thereof, and more specifically, it may be the commercially available Tracel MS211-70 TYPE D of the company Tramaco (same).

[0039] The foam layer may also contain conventional additives. For example, additives such as antioxidants and antistatic agents may be included within an appropriate content range.

[0040] Here, phenolic antioxidants, phosphite-based antioxidants, thiodipropionate sygergists, etc., may be used as antioxidants.

[0041] In addition to antioxidants and antistatic agents, other additives may also be included, and the use of additives can be easily carried out by a person with ordinary knowledge in this field.

[0042] The thickness of the foam layer is not limited, but specifically, the foam layer may have an average thickness of 1.5 to 2 mm, and more specifically, may have an average thickness of 2 mm.

[0043] If the thickness of the foam layer is less than 1.5 mm, the lightweighting effect cannot be expected, and if the thickness of the foam layer exceeds 2 mm, mechanical properties may deteriorate.

[0044] The expansion ratio of the foam layer can be 1 to 10 times, and when the expansion ratio is within the aforementioned range, the foam layer can have the aforementioned average thickness.

[0045] The foam layer has an average weight of 2.2 to 2.3 kg, and due to the lower weight compared to conventional general injection molded products, the fuel efficiency of the vehicle can be improved.

[0046] The engine room bulkhead for an electric vehicle is constructed to include a sound-absorbing material. Specifically, the sound-absorbing material is formed on one side of the aforementioned foam layer, and specifically, is formed on the inside of the engine room where the engine is located. The sound-absorbing material may consist of a first non-woven fabric layer made of a polyester resin, a foam layer formed on one side of the first non-woven fabric layer, and a second non-woven fabric layer formed on one side of the foam layer.

[0047] The first nonwoven fabric layer and the second nonwoven fabric layer are formed from polyester nonwoven fabric and can be formed to have an areal density of 30 to 200 g / m², specifically to have an areal density of 50 to 150 g / m², and more specifically to have an areal density of 100 g / m².

[0048] If the surface density of the first nonwoven fabric layer and the second nonwoven fabric layer is less than 30 g / m², the product rigidity decreases below a predetermined range and the protective effect of the foam layer cannot be achieved, and if it exceeds 200 g / m², the product weight increases above a predetermined range and cannot achieve lightweighting.

[0049] The foam layer may be a polyurethane foam, a melamine foam, or a foam using a material having a foamed form, and specifically, it may be formed as a polyurethane foam.

[0050] The foam layer can have a density of 7 to 150 kg / m³, and specifically, a density of 20 to 100 kg / m³.

[0051] If the density of the foam layer is less than 7 kg / m³, the product rigidity decreases below a predetermined range, and if it exceeds 150 kg / m³, lightweighting cannot be achieved due to the increase in product weight.

[0052] The foam layer can have an average thickness of 2 to 50 mm, specifically an average thickness of 5 to 30 mm, and more specifically an average thickness of 10 to 20 mm.

[0053] If the average thickness of the foam layer is less than 2 mm, the product rigidity decreases and the sound absorption rate decreases, and if it exceeds 50 mm, the product weight increases, making it impossible to achieve lightweighting.

[0054] The engine room bulkhead for electric vehicles can have a power-based noise reduction of 62.4 to 65.2 dB at a frequency in the 1 / 3 Octave band of 0.4 to 6.3 kHz.

[0055] In particular, it can have excellent power-based sound attenuation at high kHz, and specifically, it can exhibit a sound insulation effect of 65 dB or more at 3.0 kHz or higher.

[0056] An engine room bulkhead for an electric vehicle according to one embodiment of the present invention is composed of a foam layer formed through foam injection and a sound-absorbing material, and not only exhibits superior lightness compared to conventional engine room bulkheads, but also provides a sound insulation effect equivalent to that of the conventional at low frequencies and a superior sound insulation effect at high frequencies.

[0057] In addition, the fuel efficiency of electric vehicles can be improved by reducing the weight of the engine compartment bulkhead.

[0059] The present invention will be described in more detail below using examples. These examples are solely for the purpose of more specifically explaining the present invention, and it is obvious to those skilled in the art that the scope of the present invention is not limited by them.

[0061] <Example>

[0062] Example 1: Engine room bulkhead for an electric vehicle

[0063] Pellet was prepared by mixing 55% by weight of polypropylene with a melt index of 10 g / lOmin measured at 230℃ and a load of 216 kg, 25% by weight of glass fiber with a fiber length of 10 mm, and 20 parts by weight of barium sulfate having a particle size of 30 μm.

[0064] Next, 3% by weight of a foaming agent (Tracel MS211-70 TYPE D) was added to 100% by weight of the manufactured pellets and foam injection was performed to produce a foamed layer with a thickness of 2 mm.

[0065] Next, a sound-absorbing material was manufactured by producing a nonwoven fabric with an area density of 30 g / m² and then forming a foam layer using polyurethane between the nonwoven fabrics with a density of 30 kg / m³ and an average thickness of 10 mm.

[0066] Finally, an engine room bulkhead for an electric vehicle was manufactured by combining a sound-absorbing material on one side of the foam layer.

[0067] At this time, the sound-absorbing material was combined so as to be placed inside the engine room.

[0069] Example 2: Engine room bulkhead for an electric vehicle

[0070] It was manufactured in the same manner as Example 1, but with an aluminum layer added to the sound-absorbing material so that it could also be used in internal combustion engines.

[0072] <Comparative Example>

[0073] Comparative example: Engine room bulkhead

[0074] An engine room bulkhead was manufactured in the same manner as in Example 1, but by general injection molding excluding the foaming agent.

[0076] <Test Example>

[0077] Test Example 1: Weight Analysis of Engine Room Bulkhead

[0078] The weight of the engine room bulkheads manufactured according to Examples 1, 2 and Comparative Example was measured and is shown in Table 1 below.

[0079] division foam layer or general injection layer sound-absorbing material Total weight Comparative example 3,404 429 3,833 Example 1 2,277 251 2,528 Example 2 2,277 429 2,528

[0080] As can be seen in Table 1 above, it can be confirmed that the engine room bulkhead for an electric vehicle manufactured according to the present invention is significantly lighter in weight than the comparative example manufactured by general injection molding.

[0081] Test Example 2: Sound Insulation Performance Analysis

[0082] The sound insulation performance of the engine room bulkheads manufactured according to Examples 1 and 2 and Comparative Examples was analyzed.

[0083] The sound insulation performance analysis was performed by measuring Power-based noise reduction (PBNR) and is shown in Figure 2.

[0084] The PBNR measurement technique utilizes ATF regarding the relationship between the volume acceleration of a point source and the sound pressure of an engine room microphone. Based on the principle of acoustic reciprocity, this technique can quantitatively measure the amount of noise reduction attributed to air transmission.

[0085] Through Test Example 1, it can be confirmed that the weight of the engine room bulkhead for electric vehicles in Examples 1 and 2 is lighter than that of the comparative example made by general injection molding.

[0086] Referring to FIGS. 2 (a) and FIGS. 2 (b), the engine room bulkhead for an electric vehicle manufactured according to Examples 1 and 2 can achieve sound insulation performance equivalent to that of the comparative example at low frequencies. However, it is worth noting that the engine room bulkhead for an electric vehicle manufactured according to Example 1 exhibits improved sound insulation performance at noise levels of 3.0 kHz or higher.

[0087] While general sound-absorbing components are characterized by superior PBNR performance as their weight increases, it can be confirmed that the engine room bulkhead manufactured according to the present invention is lighter in weight than conventional engine room bulkheads while providing equivalent or superior sound insulation performance.

[0088] Therefore, when an engine room bulkhead for an electric vehicle manufactured according to the present invention is applied to a vehicle, it can exhibit excellent sound insulation performance and improve fuel efficiency due to reduced weight.

Claims

Claim 1 An engine room bulkhead for an electric vehicle, comprising a foamed layer formed by mixing and foaming azodicarbonamide into a polymer resin composition comprising 45-65 wt% polypropylene, 20-30 wt% glass fiber, and 15-25 wt% barium sulfate (BaSO4), and a sound-absorbing material formed on one surface of the foamed layer, wherein the foamed layer is formed by mixing and foaming 1-5 wt% of the azodicarbonamide based on 100 wt% of the polymer resin composition, and the sound-absorbing material comprises a first nonwoven fabric layer made of a polyester resin, a foam layer formed on one surface of the first nonwoven fabric layer, and a second nonwoven fabric layer formed on one surface of the foam layer. Claim 2 delete Claim 3 delete Claim 4 delete Claim 5 delete Claim 6 An engine room bulkhead for an electric vehicle, wherein the foam layer has an average thickness of 1.5 to 2 mm in claim 1. Claim 7 An engine room bulkhead for an electric vehicle having an average weight of 2.2 to 2.3 kg of the foam layer in claim 1. Claim 8 delete Claim 9 An engine room bulkhead for an electric vehicle according to claim 1, having a power-based noise reduction of 62.4 to 65.2 dB at a frequency in the 1 / 3 Octave band of 0.4 to 6.3 kHz.

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