Knee protection airbag device

Abstract

To provide a knee protection airbag device which easily performs mounting onto a vehicle and easily secures a behavior of unfolding the airbag backward and upward when swelling after appropriately projecting downward from a mounted part.SOLUTION: A knee protection airbag device 10 includes: an airbag 11; an inflator 20; an airbag cover 30; and an attachment base 25 which holds them and is attached to a vehicle body side member 2. The attachment base is provided with: a holding seat 26 which is disposed on a front side of a body part 21 of the inflator and a folding part 18 of the airbag disposed below it and holds the body part and the airbag with a fastening bolt 22; and a fitting seat 27 fitted to the vehicle body side members 2 on both left and right sides of the holding seat. The airbag cover covers the surroundings of the airbag and the body part of the inflator on the rear surface 25c side of the attachment base, and is fitted to the attachment base with a fastening bolt, and an opening 39 for projection of the swollen airbag can be formed on a bottom surface side.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a knee-protecting airbag device that is mounted on the front lower side of a seat in a vehicle. [Background technology]

[0002] A conventional knee-protection airbag device includes a folded and stored knee-protection airbag, an inflator that supplies inflation gas to the airbag, an airbag cover that covers the folded and stored airbag and is pressed by the airbag upon inflation to form an opening for the airbag to protrude, and a mounting base that holds the airbag, inflator, and airbag cover and is attached to a vehicle body member (see, for example, Patent Document 1). This airbag device is a so-called "bottom-type" airbag device that is mounted on the lower front side of the seat and, upon inflation, protrudes downward from the mounting location and then deploys rearward and upward. The inflator of this airbag device includes a main body that is stored within the airbag and a fastening bolt that protrudes from the main body and also protrudes outside the airbag and is fastened to the mounting base. The airbag was configured to include a base portion that houses the inflator body and is attached to a mounting base together with the inflator body by fastening bolts, an inverted portion that extends downward from the base portion and inverts upward when inflation is complete, and an inflatable body portion that inflates so as to extend upward from the inverted portion, and was stored in a substantially rectangular tubular airbag cover by folding the upper edge side of the inflatable body portion close to the base portion.The airbag cover was configured to be formed from a sheet material made of nonwoven fabric, pressed into a substantially rectangular tubular shape, cover the periphery of the folded airbag and the inflator body, and be attached to a mounting base located above the airbag cover by passing fastening bolts through it, and have a projection opening on the bottom side. The mounting base has a retaining seat near the center in the left-right direction, with a fastening hole provided for the inflator's fastening bolt to pass through, and mounting seats are provided on both the left and right sides of the retaining seat for attachment to vehicle body members using mounting bolts, etc.

[0003] Another knee protection airbag device has a mounting base positioned at the front, and the fastening bolts of the inflator, whose main body is housed within the airbag, pass through the mounting base and a vehicle body member, and the airbag and inflator are attached to the mounting base positioned at the front (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2021-155018 [Patent Document 2] Japanese Patent Publication No. 2020-40505 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the conventional knee protection airbag device described in Patent Document 1, the inflator's fastening bolts penetrate from below to above the mounting base, and the mounting seats on both sides of the mounting base's retaining seat, located on the top surface of the airbag device, are attached to a vehicle body member located above using mounting bolts whose axial direction is aligned vertically. In other words, the knee protection airbag device described in Patent Document 1 requires working space above the mounting location to turn nuts and other fasteners when installing the airbag device in a vehicle. Therefore, in vehicles with limited space above the mounting location, it is difficult to secure working space for turning nuts and other fasteners, making installation difficult.

[0006] On the other hand, the conventional knee protection airbag device described in Patent Document 2 is configured to be attached to a vehicle body member using the inflator's fastening bolts, and when installing the airbag device in a vehicle, even if there is no space above the installation location, it can be installed to the vehicle body member as long as there is work space in front, behind, or on the left and right of the installation location. However, in this airbag device, the folded portion of the folded airbag is located behind the main body of the inflator, so the airbag tends to protrude rearward when inflated, making it difficult to adopt as a bottom-type airbag device, in which the airbag precisely protrudes downward from the installation location and then deploys rearward and upward.

[0007] The knee-protecting airbag device of the present invention solves the above-mentioned problems, and aims to provide a knee-protecting airbag device that is easy to install in a vehicle and that, when inflated, easily ensures that the airbag accurately protrudes downward from the installation location and then deploys upward and rearward. [Means for solving the problem]

[0008] The knee protection airbag device according to the present invention includes a knee protection airbag that is folded and stored; an inflator that supplies inflation gas to the airbag; an airbag cover that covers the folded and stored airbag and that is pressed by the airbag when inflated to form an opening for the airbag to protrude; a mounting base that holds the airbag, the inflator, and the airbag cover and is attached to a vehicle body member; The present invention is configured to include the following: A knee protection airbag device that is mounted on a front lower side of a seat, and that when inflated, projects downward from the mounting position and then deploys rearward and upward, the inflator comprises a main body portion accommodated in the airbag, and a fastening bolt protruding from the main body portion and protruding outside the airbag and fastened to the mounting base, The airbag, a base portion that houses the inflator body and is attached to the mounting base together with the inflator body by fastening the fastening bolts; an inverted portion that extends downward from the base portion and inverts upward when inflation is complete; an expanding main body portion that expands so as to extend upward from the inverted portion; The present invention is configured to include the following: a folded portion formed by folding the upper edge of the inflation main body portion so as to approach the base portion side is disposed below the main body portion of the inflator and is stored in the mounting portion; The mounting base is a retaining seat that is disposed in front of a main body of the inflator and a folded portion of the airbag when the inflator is mounted on a vehicle, and that attaches and holds the main body and the airbag together by fastening the fastening bolts; mounting seats disposed on both the left and right sides of the retaining seat and attached to the vehicle body member using mounting bolts whose axial directions are aligned in the front-rear direction; With It is configured as a substantially flat plate extending in the left-right direction, The airbag cover is The rear side of the mounting base covers the folded airbag and the main body of the inflator, and the fastening bolt passes through the mounting base to be attached to the mounting base, and the protrusion opening can be arranged on the bottom side.

[0009] In the knee protection airbag device of the present invention, the inflator, airbag, and airbag cover are attached to the retaining seat of the mounting base using the inflator's fastening bolts to assemble the airbag device, and then the mounting seat of the mounting base is positioned on a vehicle body member and the airbag device can be installed in the vehicle using the mounting bolts. This installation work is easy to perform because, unlike above the installation location, there are fewer vehicle-mounted components in the instrument panel in front of the seat to the front, rear, left, and right of the installation location, making it easier to secure work space, and also because the knee protection airbag device is a bottom-type device that allows easy access from the floor side with a hand, etc.

[0010] Furthermore, the folded portion of the airbag is disposed below the main body of the inflator. When activated, the folded portion is smoothly pushed downward by inflation gas discharged from the main body, pushing open the bottom side of the airbag cover and forming a protrusion opening in the airbag cover. Therefore, when activated, the folded airbag precisely protrudes downward from the mounting portion and then unfolds rearward and upward via the inverted portion, thereby inflating the inflation main body and completing inflation. Since the mounting base is disposed so as to cover the front side of the folded portion from the base portion covering the main body of the inflator to the vicinity of the base, upon completion of inflation of the airbag, the rear side of the mounting base supports the airbag from the vicinity of the base to the inverted portion near the base, ensuring a reaction force. This prevents the inflation main body from rotating downward, allowing the airbag to precisely complete inflation while protecting the knees.

[0011] Therefore, the knee protection airbag device of the present invention is easy to install in a vehicle, and when inflated, the airbag protrudes downward accurately from the installation location and then deploys upward and rearward, and further, the inflation main body of the airbag when fully inflated can be positioned at an accurate height position.

[0012] In the knee protection airbag device according to the present invention, it is desirable that the mounting base is configured so that the height positions of the fastening bolts on the retaining seat and the mounting bolts on the mounting seat are aligned in the left-right direction.

[0013] In this configuration, even when inflation gas is discharged from the inflator body, the height positions of the mounting position of the mounting base to the vehicle body member using the mounting bolts and the holding position of the inflator body using the fastening bolts are the same in the left-right direction, making it difficult for the mounting base to rotate back and forth around the mounting position, stabilizing the downward protrusion direction of the airbag and further stabilizing the inflation behavior of the airbag.Incidentally, for example, if the mounting position of the mounting base to the vehicle body member is higher than the holding position of the inflator body, the reaction force of the inflation gas discharged from the inflator body will easily cause the retaining seat below the mounting position near the position of the inflator fastening bolts to rotate forward with the mounting position as a fulcrum.If the retaining seat is deformed in such a way as to rotate forward, the inverted portion of the airbag and the inflation body will shift downward, making it difficult to accurately position the inflation body.

[0014] In the knee protection airbag device according to the present invention, it is preferable that the mounting base be made of a substantially flat metal plate having reinforcing ribs projecting from the upper and lower edges.

[0015] In this configuration, even though the mounting base is generally flat, it is resistant to bending deformation and can stably support the airbag when inflated. Furthermore, even though the mounting base is made of sheet metal, its generally flat shape extending in the left-right direction allows for weight reduction. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a schematic vertical cross-sectional view showing a knee protection airbag device according to an embodiment of the present invention mounted on a vehicle. [Figure 2]2 is a schematic enlarged vertical cross-sectional view of the vicinity of a fastening bolt of the airbag device according to the embodiment when the device is mounted on a vehicle. FIG. [Figure 3] 2 is a schematic enlarged vertical cross-sectional view of the vicinity of a mounting bolt of the airbag device according to the embodiment when the device is mounted on a vehicle. FIG. [Figure 4] 1 is a schematic perspective view of an airbag device according to an embodiment; [Figure 5] FIG. 2 is a development view illustrating the airbag cover according to the embodiment. [Figure 6] 10A to 10C are diagrams illustrating a folding process of the airbag according to the embodiment. [Figure 7] 3A to 3C are schematic vertical cross-sectional views sequentially illustrating states of the knee protection airbag device of the embodiment during activation. [Figure 8] 8A to 8C are schematic vertical cross-sectional views showing sequential states of the knee protection airbag device of the embodiment during activation, showing the state after FIG. 7. [Figure 9] FIG. 2 is a schematic vertical cross-sectional view showing a state when the knee protection airbag device of the embodiment has been activated. [Figure 10] 10A to 10C are diagrams illustrating a folding process of a modified airbag. [Figure 11] FIG. 11 is a schematic vertical cross-sectional view of the airbag shown in FIG. 10 in a state where it is mounted on a vehicle. [Figure 12] 10 is a schematic vertical cross-sectional view showing a modified example in which the orientation of the mounting bolts for mounting the mounting base to the vehicle body side member is changed. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0017] A knee protection airbag device according to one embodiment of the present invention will now be described with reference to the drawings. As shown in FIGS. 1 and 8, the knee protection airbag device 10 according to the embodiment is mounted on the front lower side of the driver's seat, more specifically, on the lower side of a front instrument panel (abbreviated as "instrument panel" as appropriate) 8, and even more specifically, on an opening 9 on the side of a lower edge 8a of the instrument panel 8 below a column cover 6 of a steering column 5, as a mounting location LP.

[0018] In this specification, the front-to-rear, up-down, and left-to-right directions correspond to the directions when the device is mounted on a vehicle. As shown in Figures 1 to 4, the longitudinal direction of the approximately rectangular shape of the mounting base 25 (described later) is defined as the left-to-right direction, the short side of the width is defined as the up-down direction, and the thickness direction is defined as the front-to-rear direction.

[0019] The airbag device 10 is a so-called "bottom-type" knee-protection airbag device 10 configured such that, when inflated, an airbag 11 (described later) protrudes downward from a mounting portion LP and then deploys rearward and upward (see FIGS. 1, 7 to 9). As shown in FIGS. 1 to 4, the airbag device 10 includes: a knee-protection airbag 11 that is folded and stored; an inflator 20 that supplies inflation gas G (see FIGS. 7 and 8) to the airbag 11; an airbag cover 30 that covers the folded and stored airbag 11 and that is pressed by the airbag 11 when inflated to form an opening 39 for the airbag 11 to protrude; and a mounting base 25 that holds the airbag 11, the inflator 20, and the airbag cover 30 and mounts them to a bracket 2 on the body 1 as a vehicle body member.

[0020] The inflator 20 is configured to include a substantially cylindrical main body 21 that is housed within the airbag 11, and fastening bolts 22 that protrude from the main body 21 and protrude outside the airbag 11 and are fastened to a mounting base 25. The main body 21 is configured with a plurality of gas discharge ports 21a (see FIG. 4) that discharge inflation gas G arranged at its tip (left end), and two fastening bolts 22 that protrude from it. Since the inflator 20 is mounted in the mounting portion LP with the axial direction of the substantially cylindrical main body 21 aligned in the left-right direction, the two fastening bolts 22 protrude forward and are arranged side by side in the left-right direction with their heights aligned.

[0021] The airbag 11 is configured to include a base portion 12 that houses the main body portion 21 of the inflator 20, an inverted portion 13 that extends downward from the base portion 12 and inverts upward when the airbag 11 is fully inflated, and an inflatable main body portion 14 that extends upward from the inverted portion 13 and inflates to protect the knees K of the driver D, and has a generally trapezoidal shape when deployed flat (see FIG. 6). The base portion 12 has through holes 12a through which each fastening bolt 22 passes, and is attached to the mounting base 25 together with the main body portion 21 of the inflator 20 by fastening the fastening bolts 22 that pass through the through holes 12a to the mounting base 25.

[0022] 6, the airbag 11 is stored in the base portion 12 with the main body 21 of the inflator 20 protruding from the through-hole 12a, and then, in a flat deployed state, is folded in a roll shape so that the tip (upper edge) 14a of the inflatable main body 14 approaches the base portion 12. In the embodiment, the airbag 11 is rolled up on the side of the vehicle body side wall 11a. The airbag 11 is stored in the mounting position LP with the rolled folded portion 18 positioned below the main body 21 of the inflator 20.

[0023] The airbag 11 is made of a woven fabric such as polyester, and when fully inflated, as shown in Fig. 9, has a vehicle body side wall portion 11a disposed on the instrument panel 8 side and an occupant side wall portion 11b disposed on the driver D side, and has a generally trapezoidal shape with a wider tip (upper edge) 14a. The airbag 11 also has multiple tethers 15 disposed inside it that connect the vehicle body side wall portion 11a and the occupant side wall portion 11b. The tethers 15 are composed of two thickness-limiting tethers 15a, 15a disposed on the side of the inflatable main body portion 14, radial tethers 15b, 15b disposed radially when viewed from the side so as to form the inverted portion 13, and a traction tether 15c that prevents the inverted portion 13 from sagging downward. The radial tethers 15b, 15b are spaced apart from each other by a shorter distance on the vehicle body side wall 11a side than on the occupant side wall 11b side, and the inverted portion 13 extends downward from the base portion 12 side and then inverts upward. The traction tether 15c is disposed so as to connect the vehicle body side wall 11a near the upper portion of the main body 21 of the inflator 20 to the occupant side wall 11b near the lower portion of the main body 21. These tethers 15 (15a, 15b, 15c) are disposed so as to connect the vehicle body side wall 11a to the occupant side wall 11b by providing gas flow passages as appropriate so as not to obstruct the flow of inflation gas G discharged from the gas discharge port 21a in the main body 21 of the inflator 20.

[0024] The mounting base 25 is made of sheet metal such as iron and has a generally flat plate shape extending in the left-right direction. When mounted on a vehicle, the mounting base 25 is disposed in front of the main body 21 of the inflator 20 and the folded portion 18 of the airbag 11, and attaches and holds the main body 21 and the airbag 11 by fastening the fastening bolts 22, and also attaches the inflator 20 and the airbag 11 to the bracket 2, which serves as a vehicle body member.

[0025] The mounting base 25 is formed by pressing a steel plate and includes a retaining seat 26 located in the center in the left-right direction, and mounting seats 27 (L, R) located on both the left and right sides of the retaining seat 26. The retaining seat 26 has fastening holes 26a arranged in the left-right direction, through which fastening bolts 22 pass, and by passing the fastening bolts 22 through the fastening holes 26a and fastening nuts 23 to the fastening bolts 22, the main body 21 of the inflator 20 and the airbag 11 are attached and held in place. The left and right mounting seats 27 (L, R) are attached to connecting seats 2a (L, R) of a bracket 2, which serves as a vehicle body member, using mounting bolts 3 whose axial direction is aligned in the front-rear direction, and include mounting holes 27a through which the mounting bolts 3 pass.

[0026] The connecting seats 2a (L, R) of the bracket 2 serving as a vehicle body member are provided with through holes 2b through which mounting bolts 3 pass and nuts 4 (weld nuts) welded to the front sides of the mounting seats 2a for screwing the mounting bolts 3, and are disposed on both the left and right sides of the mounting location LP of the airbag device 10 (see FIGS. 3 and 4). The mounting seats 27 (L, R) are attached to the connecting seats 2a by arranging the mounting seats 27L, 27R on the rear surfaces of the left and right connecting seats 2aL, 2aR, and passing the mounting bolts 3 through the mounting holes 27a and through holes 2b and fastening the mounting bolts 3 with the nuts 4, thereby attaching the mounting base 25 to the bracket 2 and enabling the airbag device 10 to be mounted in the mounting location LP.

[0027] Furthermore, when the mounting base 25 is mounted on the vehicle, the height position h of the fastening holes 26a, 26a, which are the positions of the fastening bolts 22 in the retaining seat 26, and the mounting hole 27a, which is the position of the mounting bolt 3 in the mounting seat 27 (L, R), from the bottom surface 10a of the airbag device 10 is aligned in the left-right direction.

[0028] Furthermore, although the mounting base 25 has a generally rectangular, flat plate shape extending in the left-right direction, the upper and lower edges 25a, 25b are provided with reinforcing ribs 28(U, B) each having a short protruding length. In this embodiment, the reinforcing rib 28U on the upper edge 25a protrudes toward the rear of the vehicle, and the reinforcing rib 28D on the lower edge 25b protrudes toward the front of the vehicle.

[0029] As shown in Fig. 5, the airbag cover 30 is formed from a sheet material 40 cut out from a nonwoven fabric sheet material 45. The nonwoven fabric of the embodiment is formed by bonding or entangling short fibers of polyethylene, polypropylene, polyamide, polyester, or the like with an adhesive or low-melting-point fibers.

[0030] The airbag cover 30 shares a flat bottom wall portion 31 and is provided with a central cylindrical portion 30a having a high central height and a generally rectangular cylindrical shape, and edge side cylindrical portions 30b (L, R) having a low height and a generally rectangular cylindrical shape, and is configured to cover the front, back, top and bottom of the folded airbag 11 and the main body portion 21 of the inflator 20.

[0031] The airbag cover 30 is configured to include a bottom wall portion 31 having a substantially rectangular plate shape that covers the underside of the folded portion 18 of the airbag 11, a front wall portion 32 that extends upward from a front edge 31a of the bottom wall portion 31 and abuts against a rear surface 25c of the mounting base 25, a rear wall portion 34 that extends upward from a rear edge 31b of the bottom wall portion 31 and is disposed so as to face the front wall portion 32 in the front-to-rear direction, and a ceiling wall portion 35 that covers the upper part of the main body portion 21 and the folded portion 18 of the inflator 20. The front wall portion 32 is configured to include a central portion 32a that is high in the center in the left-right direction, and edge portions 32b (L, R) that are located on both left and right sides of the central portion 32a and are lower in height than the central portion 32a. The rear wall portion 34 is similarly configured with a central portion 34a that is tall in the center in the left-right direction, and edge portions 34b (L, R) that are shorter than the central portion 34a and are arranged on both the left and right sides of the central portion 34a.

[0032] The ceiling wall portion 35 is configured to include a central portion 35a that connects the central portions 32a, 34a of the front wall portion 32 and the rear wall portion 34, and edge portions 35b (L, R) that descend from the central portion 35a with a step and connect the left and right edge portions 32b (L, R), 34b (L, R) of the front wall portion 32 and the rear wall portion 34.

[0033] In this airbag cover 30, the central tubular portion 30a is a portion that covers the main body 21 of the inflator 20 together with the folded portion 18 of the airbag 11, and the edge side tubular portions 30b (L, R) are portions that are outside the area of the main body 21 and cover only the folded portion 18 of the airbag 11. A through hole 33, through which the fastening bolt 22 passes, is formed in the front wall portion 32 of the central tubular portion 30a.

[0034] The airbag cover 30 has a bottom wall portion 31 that constitutes a door portion 36 that forms a projection opening 39 when the airbag 11 is inflated. The door portion 36 has a front edge 31a side of the bottom wall portion 31 that serves as a hinge portion when the door is opened, and a rear edge 31b side that serves as a thin-walled breakable portion 37 that breaks when the airbag 11 is inflated.

[0035] As shown in FIG. 5 , when the sheet material 40 forming the airbag cover 30 is laid out flat, the portion forming the bottom wall 31 is connected to the portion forming the central portion 34a and the edge portions 34b (L, R) of the rear wall 34, the portion forming the rear wall 34 is connected to the portion forming the central portion 35a and the edge portions 35b (L, R) of the ceiling wall 35, and the portion forming the ceiling wall 35 is connected to the portion forming the central portion 32a and the edge portions 32b (L, R) of the front wall 32. At the boundary between the portions, bending grooves 41 are formed by pressing to facilitate creases, and at the portion forming the breakable portion 37, breaking grooves 42 are formed by pressing to facilitate breaking. Each bending groove 41 is pre-formed to facilitate bending during assembly of the airbag device 10.

[0036] In addition, joining portions 31c, 32c are arranged on the front edge 31a side of the bottom wall portion 31 and the lower edge side of the front wall portion 32, and are joined to each other by heat sealing or the like.When assembling the airbag cover 30, the airbag cover 30 can be assembled by bending each bending groove 41 of the sheet material 40 to join the joining portions 31c, 32c to each other and forming the central tubular portion 30a and the edge side tubular portion 30b.

[0037] 6, the airbag 11 is folded by rolling the upper edge 14a toward the base portion 12 to form the folded portion 18. Next, the fastening bolts 22 are passed through the through-holes 33 in the front wall 32 of the airbag cover 30, and the main body 21 of the inflator 20 and the folded airbag 11 are positioned on the rear side of the front wall 32. The bending grooves 41 are bent to position the top wall 35, the front wall 32, and the bottom wall 31 around the folded airbag 11 with the main body 21 housed therein. Finally, the bottom wall 31 and the front wall 32 are joined together by overlapping their joining margins 31c, 32c, to form the airbag cover 30. Thereafter, each fastening bolt 22, 22 is passed through the fastening hole 26a of the retaining seat 26 of the mounting base 25, and the nut 23 is tightened onto each fastening bolt 22, whereby the main body 21 of the inflator 20 and the airbag 11 can be attached to the mounting base 25, and the airbag device 10 can be assembled.

[0038] After assembling the airbag device 10, the activation signal wire (not shown) extending from the inflator 20 is connected to a predetermined connector, and the mounting seats 27 (L, R) of the mounting base 25 are positioned on the rear surfaces of the left and right connecting seats 2a of the bracket 2 serving as the vehicle body side member, and the mounting bolts 3 are passed through the mounting holes 27a and the through holes 2b and tightened to the nuts 4, whereby the mounting base 25 is attached to the bracket 2 on the body 1 side, and the airbag device 10 can be mounted in the mounting location LP of the vehicle.

[0039] After the airbag device 10 is installed, when the inflator 20 is activated, inflation gas G is discharged from the gas discharge port 21a, and the airbag 11 expands and inflates, as shown in A and B of Figures 7 and A and B of Figures 8, rupturing the intended rupture portion 37 of the airbag cover 30 and pushing open the door portion 36 to form a projection opening 39, and then passes through the projection opening 39 and is positioned in front of the knees K of the driver D (see Figure 9).

[0040] In the airbag device 10 of this embodiment, the inflator 20, airbag 11, and airbag cover 30 are attached to the retaining seat 26 of the mounting base 25 using the fastening bolts 22 of the inflator 20 to assemble the airbag device 10. Then, the mounting seats 27 (L, R) of the mounting base 25 are placed on the connecting seat 2a of the bracket 2, which serves as a vehicle body member, and the airbag device 10 can be mounted on the vehicle by using the mounting bolts 3 that pass through the mounting seats 27 and the connecting seat 2a and are fastened to the nuts 4. This mounting operation is facilitated by the fact that, unlike above the mounting location LP, there are fewer vehicle-mounted components (such as a steering device and an air conditioning device) in the instrument panel 8 in front of the seats at the front, rear, left, and right of the mounting location LP, making it easier to secure work space. This is also due to the fact that the knee-protection airbag device 10 is a bottom type that allows easy access from the floor F side.

[0041] Furthermore, the folded portion 18 of the airbag 11 is disposed below the main body 21 of the inflator 20, and upon activation, the folded portion 18 is smoothly pushed downward by the inflation gas G discharged from the main body 21 (see A and B in Fig. 7), which pushes open the bottom side (bottom wall 31 side) of the airbag cover 30 and forms a protrusion opening 39 in the airbag cover 30. Therefore, upon activation, the folded airbag 11 accurately protrudes downward from the mounting portion LP, and then unfolds rearward and upward by the inverting portion 13, and then, as shown in A and B in Fig. 8 and Fig. 9, inflates the inflation main body 14, completing inflation. In this case, since the mounting base 25 is arranged to cover the front side of the folded portion 18 near the base 12, from the base 12 that covers the main body 21 of the inflator 20, when the airbag 11 is fully inflated, the airbag 11 is supported on the rear surface 25c of the mounting base 25 from near the base 12 to the inverted portion 13 near the base 12, ensuring a reaction force, thereby preventing a downward rotational behavior of the inflated main body 14, and allowing the airbag 11 to fully inflate while properly protecting the knees K.

[0042] Therefore, the knee protection airbag device 10 of the embodiment can be easily mounted on a vehicle, and the airbag 11 can be ensured to accurately protrude downward from the mounting location LP when inflated and then deploy upward and rearward, and further, the inflation main body portion 14 of the airbag 11 can be positioned at an accurate height position when inflation is complete.

[0043] In the knee protection airbag device 10 of the embodiment, the mounting base 25 is configured so that the position of the fastening bolt 22 on the retaining seat 26 and the position of the mounting bolt 3 on the mounting seat 27 (L, R) are aligned in the left-right direction. In the embodiment, the height position h from the bottom surface 10a of the airbag device 10 is aligned between the position P2 of the fastening bolt 22 and the position P1 of the mounting bolt 3. In other words, in the case of the embodiment, the position (retaining position) P2 of the fastening hole 26a in the mounting base 25, through which the fastening bolt 22 passes, and the position P1 of the mounting hole 27a in the mounting base 25, through which the mounting bolt 3 passes, are aligned in height h from the bottom surface 10a of the airbag device 10.

[0044] Therefore, in the embodiment, even when inflation gas G is discharged from the main body 21 of the inflator 20, the height position h of the mounting position (position of mounting hole 27a) P1 with the bracket 2 as a vehicle body side member using the mounting bolt 3 on the mounting base 25 and the holding position (position of fastening hole 26a) P2 of the main body 21 of the inflator 20 using the fastening bolt 22 are the same in the left-right direction, making it difficult for the mounting base 25 to rotate back and forth around the mounting position P1, stabilizing the downward protrusion direction of the airbag 11, etc., and further stabilizing the inflation behavior of the airbag 11. Incidentally, for example, if the mounting position P3 (see the two-dot chain line in Figure 2) of the mounting base 25 on the vehicle body side member is higher than the holding position P2 of the main body 21 of the inflator 20, the reaction force of the inflation gas G discharged from the main body 21 of the inflator 20 will tend to rotate forward around the mounting position P3, near the position P2 of the fastening bolt 22 of the inflator 20 on the retaining seat 26 below the mounting position P3, and if the retaining seat 26 is deformed so as to rotate forward, the inverted portion 13 and the inflation main body 14 of the airbag 11 will shift downward, making it difficult to position the inflation main body 14 accurately.

[0045] In the knee protection airbag device 10 of the embodiment, the mounting base 25 is made of a substantially flat metal plate having reinforcing ribs 28 (U, D) protruding from the upper and lower edges 25a, 25b, respectively.

[0046] Therefore, in the embodiment, even though the mounting base 25 has a substantially flat plate shape, it is resistant to bending deformation and can stably support the inflated airbag 11. Furthermore, even though the mounting base 25 is made of sheet metal, it has a substantially flat plate shape extending in the left-right direction, which allows for weight reduction.

[0047] In the embodiment, the folded portion 18 of the airbag 11, which is disposed below the main body 21 of the inflator 20, is formed by roll-folding so that the upper edge 14a in the flat deployed state is closer to the base portion 12. However, as shown in Figures 10 and 11, the folded portion 18A may be formed by folding both left and right edge portions 18b of the folded portion 18, which is roll-folded as in the embodiment, downward toward the center portion 18a in the left-right direction of the folded portion 18. Even in this case, the folded portion 18A, i.e., the center portion 18a and the edge portions 18b, are disposed below the main body 21 of the inflator 20 and are mounted covered by the airbag cover 30A. Therefore, when the inflator 20 is activated, the airbag 11 provided with the folded portion 18A smoothly protrudes downward from the mounting position LP, then turns over, and deploys rearward and upward to complete inflation.

[0048] In addition, in the embodiment, when attaching the mounting seats 27(L, R) of the mounting base 25 to the bracket 2 serving as a vehicle body member, the mounting bolts 3 are used, which pass through the mounting holes 27a from rear to front, but as shown in Fig. 12, nuts (weld nuts) 4B may be provided on the front peripheral edge of the mounting holes 27a on the mounting base 25 on the mounting seat 27(L, R) side, and the mounting bolts 3B may be passed through the mounting holes 27a from the front and fastened to the nuts 4B to attach the mounting seat 27 to the bracket 2. Of course, although weld nuts are used as the nuts 4 in the embodiment and the nuts 4B in Fig. 12, the nuts 4, 4B may be fastened to the mounting bolts 3, 3B that pass through the mounting holes 27a or the through holes 2b separately.

[0049] Furthermore, in the embodiment, the knee protection airbag device 10 mounted on the front lower side of the driver's seat has been described, but the present invention can be applied to knee protection airbag devices mounted on the front lower side of seats other than the driver's seat, including the passenger seat. [Explanation of symbols]

[0050] 2...(Vehicle body side member) bracket, 2a(L,R)...connecting seat, 3...mounting bolt, 10...knee protection airbag device, 11...airbag, 12...base portion, 13...inverting portion, 14...inflatable main body portion, 14a...upper edge, 18, 18A...folding portion, 20...inflator, 21...main body portion, 22...fastening bolt, 25...mounting base, 25c...rear surface, 26...retaining seat, 27(L,R)...mounting seat, 28(U,D)...reinforcing rib, 30, 30A...airbag cover, 36...door portion, 37...proposed breaking portion, 38...hinge portion, 39...projection opening, LP...mounting location, h...height position, P1...(position of mounting bolt) mounting position, P2...(position of fastening bolt) holding position, G...inflation gas.

Claims

1. A folded and stored knee protection airbag, an inflator that supplies inflation gas to the airbag; an airbag cover that covers the folded and stored airbag and that is pressed by the airbag when inflated to form an opening for the airbag to protrude; a mounting base that holds the airbag, the inflator, and the airbag cover and is attached to a vehicle body member; The present invention is configured to include the following: A knee protection airbag device that is mounted on a front lower side of a seat, and that when inflated, projects downward from the mounting position and then deploys rearward and upward, the inflator comprises a main body portion accommodated in the airbag, and a fastening bolt protruding from the main body portion and protruding outside the airbag and fastened to the mounting base, The airbag, a base portion that houses the inflator body and is attached to the mounting base together with the inflator body by fastening the fastening bolts; an inverted portion that extends downward from the base portion and inverts upward when inflation is complete; an expanding main body portion that expands so as to extend upward from the inverted portion; The present invention is configured to include the following: a folded portion formed by folding the upper edge of the inflation main body portion so as to approach the base portion side is disposed below the main body portion of the inflator and is stored in the mounting portion; The mounting base is a retaining seat that is disposed in front of a main body of the inflator and a folded portion of the airbag when the inflator is mounted on a vehicle, and that attaches and holds the main body and the airbag together by fastening the fastening bolts; mounting seats disposed on both the left and right sides of the retaining seat and attached to the vehicle body member using mounting bolts whose axial directions are aligned in the front-rear direction; With It is configured as a substantially flat plate extending in the left-right direction, The airbag cover a rear surface of the mounting base that covers the folded airbag and the main body of the inflator, the fastening bolt passes through the mounting base to be attached to the mounting base, and the protrusion opening can be disposed on the bottom surface of the mounting base.

2. 2. The knee protection airbag device according to claim 1, wherein the mounting base is configured so that the height positions of the fastening bolts on the retaining seat and the mounting bolts on the mounting seat are aligned in the left-right direction.

3. 3. The knee protection airbag device according to claim 1, wherein the mounting base is made of a substantially flat metal plate having reinforcing ribs projecting from the upper and lower edges.

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