Hood airbag arrangement for a motor vehicle

Abstract

Hood airbag arrangement with a two-shell hood having an airbag (5) integrated between the outer shell (2) and the inner shell (3), wherein the inner shell (3) provides a stiffening structure and the integrated airbag (5) is arranged between the outer shell (2) and the inner shell (3) in such a way that the hood is safely raised when the airbag (5) is triggered, characterized in that the airbag (5) has cutouts (8) without material through which the outer shell (2) is bonded to the inner shell (3), wherein the airbag (5) is applied before the shells (2,3) are painted.

Description

[0001] The invention relates to a hood airbag arrangement for a motor vehicle according to claim 1.

[0002] In a frontal collision involving a motor vehicle, especially a passenger car, with pedestrians, the pedestrians impact the front bumper, the hood, and the windshield.

[0003] The hood is designed as a spring, absorbing the pedestrian's impact energy by deforming towards the drivetrain beneath it. This requires a free deformation space under the hood to prevent serious injuries in the event of a pedestrian's head impact and to allow for energy absorption.

[0004] This results in a restriction or limitation on the powertrain height with regard to the non-deformable points (fuel pumps, cylinder head, etc.) on the upper surface of the powertrain. Non-deformable in this case means that the components have a stiffness above a certain threshold, which, in the event of a pedestrian head impact, could lead to head injuries after deformation of the hood towards the engine.

[0005] The restriction or limitation of the installation space available for the powertrain is defined vertically or horizontally in the z-direction by an offset of the inner hood surface and represents the required free hood deformation space necessary to prevent head injuries in a pedestrian head impact. This limitation of the powertrain installation space must not be violated by the non-deformable powertrain components.

[0006] In current vehicles, this restriction or limitation contradicts the increasing height of powertrains due to high engine displacement and limited installation space in front of or behind the engine, and at the same time the requirements for lower hoods driven by customer viewing angles, improved aerodynamics (fuel efficiency) and styling.

[0007] To mitigate the impact on pedestrians, Volvo is known to use a so-called pedestrian airbag, which is positioned between the hood and the windshield. In the event of a frontal collision, this airbag lifts the hood and covers the lower part of the windshield. This lifting action is intended to allow the hood to spring back and create a gap between it and the engine components below.

[0008] From paragraphs [0018, 0019 & 0031 - 0033] of DE 1030560460A1 it is known to design a two-shell engine hood with constantly inflated compressed air chambers arranged between the shells, wherein additionally actively actuated overpressure chambers can be used to raise the engine hood in an airbag-like manner in the event of an impact and thus create a deformation space.

[0009] In contrast, the object of the present invention is to provide an improved alternative hood airbag arrangement that allows for the simple manufacture of the two-shell hood with integrated airbag and still achieves good triggering and protection results.

[0010] This problem is solved by the hood airbag arrangement described in claim 1. Advantageous embodiments are described in the dependent claims and the description.

[0011] According to the invention, it has been recognized that if a hood airbag arrangement is equipped with a two-shell hood, which has an airbag integrated between the outer shell and the inner shell, and the inner shell provides a stiffening structure, and the integrated airbag is arranged between the outer shell and the inner shell in such a way that the airbag has cutouts without material to allow the connection between the outer shell and the inner shell, it is possible to provide simple assembly and still increase the energy absorption capacity of the hood and thus raise the tolerable lower restriction for the hood deformation space in order to allow larger powertrains in z-height or to improve pedestrian protection.

[0012] According to the invention, the airbag is applied before the shells are painted. Alternatively, the airbag can be inserted after the surface treatment of the hood (chemical cleaning and corrosion protection), but before the start of painting and bonding of the upper and lower shells together with the adhesive areas / bonding points between the shells, and the upper and lower shells are bonded / bonded together before the start of painting.

[0013] It goes without saying that more than one airbag can be provided.

[0014] The cutouts can, in principle, take on any possible shape. Rectangular, oval, or other cutout shapes are all possible.

[0015] In a preferred embodiment, the connection between the outer and inner shells is bonded through the cutouts in such a way that the outer shell is separated from the inner shell when the airbag is deployed. In other words, the pressure exerted by the airbag's expansion breaks the adhesive bond between the outer shell and the structural inner shell, causing the outer shell to detach and provide an enlarged deformation space above the engine components.

[0016] The hood incorporates a structural support frame that provides rigidity to the assembly under normal driving conditions, thanks to the inner underside shell. The upper or outer shell of the hood (hood trim) is made of thin / soft metal or plastic. The two shells are bonded together using localized adhesives. The integrated airbag is located between these two shells and may also be secured with adhesive. The airbag system can consist of one or more airbags distributed across the entire hood surface.

[0017] According to the invention, the airbag has cutouts or areas without airbag material to enable an adhesive bond between the upper and lower hood trim or outer and inner shell.

[0018] Furthermore, the airbag is primarily designed as interconnected channels arranged along the stiffening inner shell structure, with the stiffening inner shell structure having free areas to save weight.

[0019] In another preferred variant, the airbag is arranged in such a way that, upon deployment, it expands through the cutouts in the stiffening hood substructure of the inner shell. In other words, the inner shell does not detach from the outer shell, but rather the airbag expands through the open areas to allow the hood to lift or be cushioned.

[0020] Preferably, the airbag is attached to the outer shell, in particular by gluing.

[0021] The outer and / or inner shell of the engine hood can be made of steel, plastic, or fiber-reinforced plastic. The material used for the outer and inner shells of the engine hood is therefore variable. It can be steel, plastic, or fiber-reinforced plastic (e.g., CFRP), and the shells and their structure can be selected and designed differently.

[0022] According to current technology, there are usually five stages of painting / surface treatment (source e.g. https: / / www.porscheleipzig.com / produktion / lackiererei): 1. Pretreatment of the welded sheet metal structure (cleaning with strong chemical agents); 2. Cathodic dip coating “KTL” (e.g. including drying at 175°C for e.g. 50 min); 3. PVC application (adhesive, seals, etc.); 4. Filler application and drying; 5. Base coat and clear coat application at, for example, 175°C for 50 minutes

[0023] The airbag can be sensibly applied to the corrosion protection layer created by cathodic dip painting (step 3) if the outer shell is made of steel. Alternatively, the airbag can be applied before the shells are painted (step 4).

[0024] For a classic sheet metal hood, the sheet metal parts are typically pre-treated and coated with corrosion protection before assembly or installation of the airbag (one or more are possible). The two structural halves are then bonded together to meet specific minimum surface requirements, but not welded to avoid damaging the airbag with heat. The hood's upper surface can then be folded over the supporting structure. Finally, the upper surface is painted, taking care to maintain a low temperature (e.g., 60°C) and allowing for a longer drying time.

[0025] It is also conceivable that the outer sheet metal and substructure could be bonded together, already painted, with the airbag sandwiched between them. For this, the paint would be left out in the areas where the adhesive would be applied, for example, using stickers that can be removed later. The structural adhesive would then be applied subsequently at the designated locations.

[0026] To protect the airbag from damage caused by the paint, the airbag fabric could be coated accordingly, or a material could be selected that is chemically resistant to paints.

[0027] If a paint that dries at lower temperatures, preferably not exceeding approximately 175 °C, is used for coating, the airbag fabric can be protected. Alternatively, the airbag can be made of a material that can tolerate the common paint drying temperature of approximately 175 °C without damage.

[0028] Ultimately, the requirement for an airbag is to maintain an airtight seal and a specific volume after inflation, or to prevent pressure loss after inflation, in order to transfer the pressure to the surrounding components in the form of deformation and, if necessary, to rupture the adhesive bonds between the outer and inner shells. The airbag's inflation pressure should therefore be chosen to meet the first scenario of the adhesive forces in order to achieve the ideal result after deployment: an increase in the distance between the two shells.

[0029] Further details of the invention will become apparent from the following description of exemplary embodiments with reference to the drawings, in which Fig. 1 a schematic top view of the three essential components (outer shell, airbag, inner shell) of a first variant of a hood arrangement according to the invention; Fig. 2 a schematic top view of the assembled hood assembly made of Fig. 1 where invisible lines are shown; Fig. 3 a sectional view along line AA from Fig. 3; Fig. 4 an enlarged detail view from Fig. 3; Fig. 5 a section view along line AA from Fig. 3 after the airbag has been deployed; Fig. 6 a schematic top view of the three essential components (outer shell, airbag, inner shell) of a second variant of a hood arrangement according to the invention; Fig. 7 a schematic top view of the assembled hood assembly made of Fig. 6 where invisible lines are shown; Fig. 8 a sectional view along line AA from Fig. 7 and Fig. 9 a sectional view along line AA from Fig. 7 after the airbag has been deployed.

[0030] In the Fig. 1 - Fig. Figure 5 shows a hood assembly, designated as a whole by Figure 1. This assembly essentially comprises three parts, namely an outer shell. 2 , an inner shell 3 with suggested structural reinforcements 4 and an airbag 5 .

[0031] The airbag 5 As usual, it includes a compressor or a compressed air source. 6 The airbag 5 itself is mainly a body / system of interconnected channels 7 designed along the stiffening inner shell structure 4 are arranged, with the stiffening inner shell structure having free areas 9 features to save weight, which the airbag also reflects in its geometry (see below). Fig. 2).

[0032] The airbag 5 according to the invention, it has cutouts 8without airbag material, to create an adhesive bond between the outer shell 2 and inner shell 3 to enable.

[0033] If the airbag deploys in a frontal collision 5 triggered and inflated (cf. Fig. 4) the adhesive bond between the outer shell 2 and inner shell 3 due to the increase in volume and the resulting pressure on the two inner surfaces of the hood made of outer shell 2 and inner shell 3 blasted open and the outer shell 2 rises from the inner shell 3 off, so that an enlarged deformation space D (cf. Fig. 5) for the head of pedestrian P, which effectively dampens the impact of the head of pedestrian P and also creates a distance to the engine parts 10 provides.

[0034] The in the Fig. 6 - Fig. 9 shown second variant of the whole with 11The designated hood arrangement largely corresponds to the one described above, so that corresponding parts are marked with reference symbols increased by 10 and only differences are discussed below.

[0035] In the second variant, the airbag 15 in contrast to the previous full-surface nature and the adhesive bond between the outer shell 12 and inner shell 13 through the cutouts 18 Without airbag material, it is so strong that the outer shell cannot detach. 12 from the inner shell 13 when the airbag is deployed 15 This has been done.

[0036] The airbag 15 rather it extends through the free areas 19 towards the engine parts 20 out, so that the hood arrangement 11 as a whole it stands out and thus provides a deformation space D. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 1030560460 A1

[0008]

Claims

[1] Hood airbag arrangement comprising a double-shell hood having an airbag integrated between the outer shell and the inner shell, wherein the inner shell provides a stiffening structure and the integrated airbag is arranged between the outer shell and the inner shell in such a way that the hood is safely lifted when the airbag is deployed, characterized by , that the airbag has cutouts without material to allow the connection between the outer shell and the inner shell, with the airbag being applied before the shells are painted. [2] Hood airbag arrangement comprising a double-shell hood having an airbag integrated between the outer shell and the inner shell, wherein the inner shell provides a stiffening structure and the integrated airbag is arranged between the outer shell and the inner shell in such a way that the hood is safely lifted when the airbag is deployed, characterized by, that the airbag has cutouts without material to allow the connection between the outer shell and inner shell, wherein the airbag is inserted after the surface treatment of the hood (chemical cleaning and corrosion protection), but before the start of painting and bonding of the upper and lower shells together with the adhesive areas / bonding points between the shells, and the upper and lower shells are connected / bonded together before the start of painting. [3] Hood airbag arrangement according to claim 1 or 2, characterized by , that the airbag is applied to the corrosion protection layer applied by cathodic dip painting if the outer shell is made of steel. [4] Hood airbag arrangement according to any one of the preceding claims, characterized by that the airbag fabric is coated accordingly or is made of a material that is chemically resistant to paints. [5] Hood airbag arrangement according to any one of the preceding claims, characterized by , that the connection between the outer shell and the inner shell is glued through the cutouts in such a way that the outer shell is separated from the inner shell when the airbag is triggered. [6] Hood airbag arrangement according to any one of the preceding claims, characterized by , that the airbag is arranged in such a way that it expands upon deployment due to the stiffening construction of the inner shell. [7] Hood airbag arrangement according to any one of the preceding claims, characterized by that the airbag is attached to the outer shell, in particular glued on. [8] Hood airbag arrangement according to any one of the preceding claims, characterized by that the outer shell and / or inner shell are made of steel, plastic or fiber-reinforced plastic. [9] Hood airbag arrangement according to any one of the preceding claims, characterized bythat a paint is used which dries at lower temperatures, preferably around 175 °C. [10] Hood airbag arrangement according to any one of the preceding claims 1 to 8, characterized by that the airbag is made of a material that can tolerate the common paint drying temperature of approximately 175 °C without damage.

Images