Air bag for pedestrian protection

Abstract

To suppress internal pressure increase and improve pedestrian protection performance at a pedestrian input late stage while ensuring impact absorption performance at a pedestrian input initial stage.SOLUTION: An air bag for pedestrian protection is stored in a case, which is located near a rear end of a vehicle hood panel and has an opening, in a folded state, jumps out of the opening by inflow of a fluid for inflation to cover a top face of a front pillar, and is formed into a bag shape. The air bag for pedestrian protection comprises an outer peripheral dewing part in which a plurality of panels are sewn together with an inflow port formed to allow the fluid for inflation to flow therein. The outer peripheral sewing part has a general sewing part, and a fragile sewing part that is more likely to break than the general sewing part.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a pedestrian protection airbag mounted on a vehicle. [Background technology]

[0002] Airbag devices are known that protect pedestrians by deploying an airbag near the rear end of a hood panel during a vehicle collision (see, for example, Patent Documents 1 and 2). These airbag devices include a pedestrian protection airbag that is stored in a folded state in a case with an opening that is positioned below the rear end of the hood panel before a vehicle collision, and a high-pressure generating source such as an inflator that generates inflation fluid such as gas and supplies it to the pedestrian protection airbag during a vehicle collision. When a vehicle collides, such airbag devices generate inflation fluid using the high-pressure generating source, supply the inflation fluid to the pedestrian protection airbag, and cause the pedestrian protection airbag to protrude from the opening in the case and deploy, thereby protecting the pedestrian.

[0003] The pedestrian protection airbag described above is formed in a bag-like shape to contain the fluid supplied for deployment, and is arranged to cover the upper surface of the vehicle's front pillar when deployed. A typical method for forming a bag-like airbag is to use a structure in which multiple panels made of flat woven fabric cut into a predetermined shape are sewn together. This bag-like airbag can quickly assume a desired three-dimensional shape when deployed, thereby improving pedestrian protection performance in the event of a vehicle collision. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-264146 [Patent Document 2] Japanese Patent Application Publication No. 2020-157839 Summary of the Invention [Problem to be solved by the invention]

[0005] In an airbag constructed by sewing together multiple panels as described above, the airbag has a perimeter sewn portion. The perimeter sewn portion is a linear portion where the multiple panels are sewn together, and is formed excluding the inlet portion through which the inflation fluid can flow. For an airbag with such a perimeter sewn portion, it is appropriate to provide a certain level of stitching strength that can withstand the maximum impact expected after deployment and inflation.

[0006] However, if the outer periphery of the airbag is sewn with a uniform stitching strength over its entire length, the internal pressure of the airbag may rise excessively when the airbag is deployed and inflated. Pedestrian protection airbags generally have a relatively small capacity because they are only required to cover the upper surface of a narrow front pillar when deployed and inflated. Therefore, if the outer periphery of the airbag is sewn with a uniform stitching strength over its entire length, the internal pressure of the airbag may rise rapidly when a pedestrian is forced into the airbag, compared to a passenger protection airbag or the like, which has a relatively large capacity. Therefore, such pedestrian protection airbags have limitations in terms of pedestrian protection.

[0007] The present invention has been made in consideration of the above circumstances, and has an object to provide a pedestrian protection airbag that can improve pedestrian protection performance by ensuring impact absorption performance in the early stage of pedestrian input while suppressing internal pressure increase in the later stage of pedestrian input. [Means for solving the problem]

[0008] One aspect of the present invention is a bag-shaped pedestrian protection airbag that is stored in a folded state in a case that is positioned near the rear end of a vehicle hood panel and has an opening, and that pops out of the opening when inflation fluid flows in to cover the upper surface of the front pillar, and that has a peripheral stitched portion where multiple panels are sewn together to form an inlet through which the inflation fluid can flow in, and the peripheral stitched portion has a general stitched portion and a fragile stitched portion that is more likely to break than the general stitched portion.

[0009] According to this configuration, it is possible to improve pedestrian protection performance by ensuring impact absorption performance in the early stage of pedestrian input and suppressing an increase in internal pressure in the later stage of pedestrian input. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a perspective view showing a vehicle in which a pedestrian protection airbag according to an embodiment of the present invention is deployed and inflated; [Figure 2] 1 is a view showing a state in which a pedestrian protection airbag (for a left front pillar) according to an embodiment is inflated and deployed, as viewed from above the vehicle. [Figure 3] 1 is a view showing a state in which a pedestrian protection airbag according to an embodiment is inflated and deployed, as viewed from the side of a vehicle. [Figure 4] 4 is a cross-sectional view of the pedestrian protection airbag shown in FIG. 2 taken along line IV-IV. [Figure 5] 3 is a plan view of a main part of a periphery stitching portion of the pedestrian protection airbag according to the embodiment. FIG. [Figure 6] 6 is a cross-sectional view of the pedestrian protection airbag (inflated state) according to the embodiment taken along line VI-VI in FIG. 5. [Figure 7] 7 is a cross-sectional view of the pedestrian protection airbag (inflated and deployed) according to the embodiment taken along line VII-VII in FIG. 5. FIG. [Figure 8] 10 is a diagram showing the effect of the pedestrian protection airbag of the embodiment compared with a comparative pedestrian protection airbag having no weak stitching portion. FIG. [Figure 9]FIG. 10 is a plan view of a main portion of a periphery stitching portion of a pedestrian protection airbag according to a modified embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] Specific embodiments of the pedestrian protection airbag according to the present invention will be described below with reference to Figures 1 to 8. In this embodiment, the terms "front," "rear," "right," "left," "upper," and "lower" are based on the direction of the vehicle in which the pedestrian protection airbag is installed, and for example, "front" means the side ahead as the vehicle moves forward.

[0012] The pedestrian protection airbag 20 of this embodiment is a bag-shaped member that is mounted on the vehicle 1 and protects a pedestrian in the event of a collision with the vehicle 1. The term "pedestrian" refers primarily to a person walking or running on the road, and may include vulnerable road users such as wheelchair users and cyclists, as well as animals such as dogs and cats, and even inanimate objects such as robots. The vehicle 1 may be an internal combustion engine vehicle, an electric vehicle, a fuel cell vehicle, or the like, and is a vehicle in which the passenger compartment is separated by pillars. Hereinafter, the pedestrian protection airbag 20 will be simply referred to as the airbag 20.

[0013] The airbags 20 can cover the upper surfaces of the front pillars 2 disposed on the left and right sides of the vehicle 1. One airbag 20 is disposed on each side corresponding to the left and right front pillars 2. Each airbag 20 has a capacity of, for example, 50 to 90 liters, and preferably about 70 liters.

[0014] As long as the airbags 20 inflate to a range that can cover the upper surfaces of the left and right front pillars 2, as described above, they may be disposed one on each side corresponding to the left and right front pillars 2, or one airbag may be mounted on the vehicle 1. Furthermore, when one airbag 20 is mounted on the vehicle 1, the airbag 20 may have a function of lifting up the rear end of the vehicle hood panel 3. The vehicle hood panel 3 is a panel member that covers the battery, engine, and upper portions of the front storage compartment that are disposed at the front of the vehicle interior.

[0015] The airbag 20 is in a folded state before the inflation fluid flows in, and unfolds and inflates when the inflation fluid flows in. The airbag 20 is housed in a case 10. The case 10 is formed in a case shape with an accommodation space. It is disposed near the rear end of the vehicle hood panel 3, for example, below the rear end. The case 10 is attached and fixed to the structure of the vehicle 1 by the bottom wall and side walls.

[0016] The case 10 has an opening 11. The opening 11 is an outlet for deploying and inflating the airbag 20 from within the case 10. The opening 11 is provided in the upper part of the case 10 and is formed in a rectangular or circular shape that allows the airbag 20 to deploy and inflate. The airbag 20 is stored in a folded state within the case 10 before the inflation fluid flows in, and after the inflation fluid flows in, it protrudes upward from the opening 11 and deploys and inflates toward the front pillar 2. The case 10 is able to support the airbag 20 without moving even when it receives a reaction force from the airbag 20 when the airbag 20 deploys and inflates, and is also able to stably receive the airbag 20 even if a pedestrian to be protected comes into contact with the airbag 20.

[0017] The inflation fluid flowing into the airbag 20 is gas. This inflation fluid is generated by a high-pressure source 12. The gas generated by the high-pressure source 12 is introduced into the airbag 20, causing the airbag 20 to expand and inflate. The high-pressure source 12 may be an inflator that generates gas by ignition using a gas generating agent, or may be one that generates gas by rupturing the wall of a high-pressure container. The inflation fluid may be, for example, a liquid or gel instead of gas.

[0018] The high-pressure source 12 may be located entirely outside the airbag 20, or partly or entirely inside the airbag 20. The high-pressure source 12 may be located inside the case 10, or may be located below the bottom wall of the case 10 and connected to the inlet of the airbag 20 through a hole in the bottom wall.

[0019] The material of the airbag 20 is preferably a foldable and deployable material, and is preferably a flexible and high-strength material. The material of the airbag 20 may be, for example, a woven fabric made of high-strength resin fibers such as polyester or polyamide.

[0020] The airbag 20 may be formed in an arm shape or a hollow pillar shape that, when deployed and inflated, can cover the upper surface of each front pillar 2 from the end on the vehicle hood panel 3 side to the end on the vehicle roof 4 side, as shown in Figure 1, or may be formed in a wide shape that includes at least the area between the left and right ends of each front pillar 2 and includes a part of the windshield glass 5 adjacent to the front pillar 2 on the vehicle center side, or may be formed in a shape that includes particularly the left and right ends of the rear end of the vehicle hood panel 3.

[0021] The airbag 20 is made up of a plurality of panels 21 sewn together. The airbag 20 is made up of a plurality of panels 21 sewn together to form a single bag. The number of panels 21 constituting the airbag 20 is, for example, two. Hereinafter, the two panels 21 will be referred to as panels 21a and 21b as appropriate. The panels 21a and 21b are each formed in the shape of a flat panel.

[0022] The two panels 21a, 21b are each flatly configured so that the cross-sectional shape of the airbag 20 will be a desired shape when inflated and deployed. The panels 21a, 21b are each formed by cutting a flat woven fabric into a predetermined shape. The shapes of the panels 21a and 21b may be the same as or different from each other. Furthermore, the airbag 20 corresponding to the right front pillar 2 of the vehicle 1 and the airbag 20 corresponding to the left front pillar 2 of the vehicle 1 may be configured so that their cross-sectional shapes are bilaterally symmetrical to each other when inflated and deployed.

[0023] The airbag 20 has a perimeter sewn portion 22. The perimeter sewn portion 22 is a portion where two panels 21a, 21b are sewn together. Specifically, the perimeter sewn portion 22 is a portion where the two panels 21a, 21b are sewn together in a state where an inlet 23 through which inflation fluid can flow into the airbag 20 is formed. The airbag 20 is formed into a bag shape with the inlet 23 through which inflation fluid can flow by sewing the outer peripheries of the two overlapping panels 21a, 21b together with the perimeter sewn portion 22.

[0024] The perimeter sewn portion 22 extends linearly using thread. The perimeter sewn portion 22 is formed mainly along the edges of the panels 21a and 21b at locations located inward from the edges. One end and the other end of the perimeter sewn portion 22 face the inlet 23. The perimeter sewn portion 22 is continuous between one end and the other end.

[0025] The perimeter sewn portion 22 may be limited to thread, but may also include a portion where the two panels 21a, 21b are sewn together with thread. The perimeter sewn portion 22 may be sewn with a single thread in the extension direction (the thread itself may be a bundle of multiple fibers), or may be sewn with multiple threads arranged at predetermined intervals in the width direction perpendicular to the extension direction.

[0026] 4, the airbag 20 is configured so that, when deployed and inflated, the panel 21a is positioned at the top and the panel 21b is positioned at the bottom, contacting the front pillar 2. In other words, when deployed and inflated, the airbag 20 is configured so that the outer periphery sewn portions 22 are positioned on the right and left sides of the circumferential position of the airbag 20 without contacting the front pillar 2. Hereinafter, the panel 21a will be referred to as the front panel 21a, and the panel 21b will be referred to as the back panel 21b, as appropriate.

[0027] The periphery sewn portion 22 is not sewn with a uniform strength throughout, but is configured so that some portions are easily torn. That is, as shown in Figures 5, 6, and 7, the periphery sewn portion 22 has regular sewn portions 25 and weak sewn portions 26. The weak sewn portions 26 are portions of the periphery sewn portion 22 that are more easily torn than the regular sewn portions 25. Note that "sewn strength" refers to the degree of resistance to tearing of the seam between the front panel 21a and the back panel 21b, and "breakage" refers to the tearing of the stitching.

[0028] When the internal pressure of the airbag 20 increases due to the inflow of inflation fluid, the seams of the frangible sewn portions 26 tear before the seams of the regular sewn portions 25. As shown in Figure 8, the timing at which the seams of the frangible sewn portions 26 tear is when the internal pressure of the airbag 20 rises once due to the inflow of inflation fluid, then begins to decrease as the inflow of inflation fluid stops, and then the internal pressure of the airbag 20 rises again due to the pedestrian's impact with the airbag 20 and reaches a predetermined pressure P. This timing may be, for example, when a predetermined time Ts has elapsed since the inflator, which is the high-pressure generating source 12, was ignited.

[0029] The fragile sewn portions 26 are configured so as to be discontinuous with the general sewn portions 25. Compared to the general sewn portions 25, the fragile sewn portions 26 are formed, for example, with thinner thread, a narrower total thread width, coarser stitch spacing, and / or a shape that makes the stitches more likely to tear. Examples of a shape that makes the seams more likely to tear include the general sewn portions 25 being formed in a linear shape, such as a substantially straight or curved shape, and the fragile sewn portions 26 being formed so as to deviate from the straight line of the substantially straight general sewn portions 25 or to have a greater curvature than the curved general sewn portions 25. The fragile sewn portions 26 may be made of a material that is weaker in strength than the material of the general sewn portions 25.

[0030] The sewing strength of the weak sewn portion 26 is set to be lower than the tear strength of the fabric of the panel 21 and lower than the sewing strength of the general sewn portion 25. The sewing strength of the weak sewn portion 26 is set to be in the range of 25 kPa to 35 kPa, for example, and specifically, it is preferably set to 30 kPa.

[0031] The weak stitching 26 is provided at a position in the outer periphery stitching 22 away from the position facing the inlet 23 in the extension direction of the pillar when the airbag 20 is deployed and inflated. The weak stitching 26 is provided in one place in the outer periphery stitching 22. Specifically, the weak stitching 26 may be provided on the outer left or right side of the vehicle 1 in the outer periphery stitching 22, but is preferably provided near the center of the vehicle 1. The reason for locating the weak stitching 26 at the center is that it is effective to place the weak stitching 26 at a position inside the airbag 20 that is likely to be pinched between the pedestrian and the front pillar 2 or the boundary between the front pillar 2 and the windshield glass 5 when a pedestrian enters the bag and is subjected to a reaction force.

[0032] Furthermore, it is preferable that the weak stitching 26 be located in the middle of the periphery stitching 22 in the extension direction. The reason for locating the weak stitching 26 in the middle is that it is effective to locate the weak stitching 26 in a location within the airbag 20 where impact is easily transmitted and response is good regardless of the location of pedestrian input. Note that the weak stitching 26 may be located in multiple separate locations on the periphery stitching 22.

[0033] As shown in Figure 5, the airbag 20 has a vent hole portion 27. The vent hole portion 27 is a ventilation portion that connects the inside of the airbag 20 to the outside of the bag. The vent hole portion 27 has the function of releasing the inflation fluid inside the airbag 20 to the outside of the bag, thereby reducing the internal pressure of the airbag 20. The vent hole portion 27 is provided at the boundary between the front panel 21a and the back panel 21b. The vent hole portion 27 connects the inside of the airbag 20 to the outside of the bag when the weak stitching portion 26 is ruptured.

[0034] The general sewn portion 25 is divided into two portions on the airbag 20, with a vent hole portion 27 sandwiched between them. That is, as shown in FIG. 2, the general sewn portion 25 has a first general sewn portion 25a and a second general sewn portion 25b. The first general sewn portion 25a and the second general sewn portion 25b each have linear stitching that is spaced apart from each other. The vent hole portion 27 is located between the first general sewn portion 25a and the second general sewn portion 25b.

[0035] The first sewn portion 25a extends linearly from one end facing the outer lateral edge of the air inlet 23 to the other end facing the lateral center of the airbag 20. The second sewn portion 25b extends linearly from one end facing the lateral center of the airbag 20 to the other end facing the lateral center of the airbag 20. The other end of the first sewn portion 25a and the other end of the second sewn portion 25b face the lateral center of the airbag 20. A vent hole portion 27 is formed between the other end of the first sewn portion 25a and the other end of the second sewn portion 25b.

[0036] The first sewn portions 25a extend linearly from the edges of the panels 21a, 21b near the other end facing the left-right center of the airbag 20 (excluding a very small line leading to that end). The second sewn portions 25b extend linearly from the edges of the panels 21a, 21b near the other end facing the left-right center of the airbag 20 (excluding a very small line leading to that end). The linear portions near the other ends of the first sewn portions 25a and the second sewn portions 25b are positioned on a substantially straight line.

[0037] The frangible sewn portion 26 is formed to connect the first general sewn portion 25a and the second general sewn portion 25b before the inflation fluid flows into the airbag 20. The frangible sewn portion 26 intersects both the first general sewn portion 25a and the second general sewn portion 25b. The ends of the frangible sewn portion 26 do not have to be in contact with the general sewn portion 25a, and do not have to be exposed to the outside at the ends of the panel 21.

[0038] The weakened sewn portion 26 is formed so as to connect the first general sewn portion 25a and the second general sewn portion 25b in a non-linear manner. Specifically, the weakened sewn portion 26 protrudes from an imaginary straight line (line segment) obtained by connecting a linear portion near the other end of the first general sewn portion 25a with a linear portion near the other end of the second general sewn portion 25b. Note that "non-linear" refers to a curved, bent, bent, wavy, etc.

[0039] The weakened stitching 26 is formed so as to close the vent hole 27. The weakened stitching 26 is formed in the panel 21 at a position from the outer edge of the vent hole 27 to the inside of the bag.

[0040] As shown in Fig. 5, the frangible sewn portion 26 has a protrusion 26a. The protrusion 26a is formed to protrude toward the inside of the airbag 20. The protrusion 26a is formed so as to interrupt the continuity of the stitching at the general sewn portion 25. The protrusion 26a protrudes toward the inside of the airbag 20 between the first general sewn portion 25a and the second general sewn portion 25b, beyond the outer edge of the airbag 20 formed by these general sewn portions 25a, 25b.

[0041] The protrusions 26a may be formed in a curved shape as a whole, or may have bent corners 26b in the middle of the protrusions 26a (see FIG. 9) to facilitate the concentration of stress when the internal pressure of the airbag 20 increases. The angle of the corners 26b should be, for example, in the range of 90° to 150°, which is effective in promoting the concentration of stress at the weakened sewn portions 26.

[0042] In this way, the airbag 20 has a peripheral sewn portion 22 where the front panel 21a and the back panel 21b are sewn together with the inlet 23 formed therein. With this configuration, the bag-shaped airbag 20 can be manufactured by sewing together a plurality of panels 21, so that the airbag 20 can be manufactured using simple materials at low cost.

[0043] When inflation fluid generated by the high-pressure source 12 flows into the airbag 20 through the inlet 23 during a vehicle collision, the airbag 20 deploys from its folded state within the case 10, protruding from the opening 11 of the case 10 and covering the upper surface of the front pillar 2. With this configuration, the airbag 20 can be interposed between the front pillar 2 and the pedestrian in the event of a vehicle collision with a pedestrian, thereby protecting the pedestrian. Furthermore, the bag-shaped airbag 20 can quickly assume a desired three-dimensional shape when deployed and inflated, thereby improving pedestrian protection performance in the event of a vehicle collision.

[0044] The outer periphery sewn portion 22 has ordinary sewn portions 25 and frangible sewn portions 26 that are more likely to rupture than the ordinary sewn portions 25. With this configuration, after the internal pressure of the airbag 20 begins to increase due to the inflow of inflation fluid, the airbag 20 continues to absorb the impact of the pedestrian without rupturing until the internal pressure of the airbag 20 reaches a predetermined pressure P due to the pedestrian's entry into the airbag 20. When the internal pressure of the airbag 20 reaches the predetermined pressure P, the seams of the frangible sewn portions 26 tear and the frangible sewn portions 26 rupture, allowing the inflation fluid inside the airbag 20 to be released to the outside of the airbag 20 through the vent holes 27.

[0045] Therefore, when the airbag 20 deploys and inflates due to a vehicle collision and a pedestrian enters the airbag, the airbag 20 can absorb the impact of the pedestrian in the early stage of the pedestrian input. Furthermore, in the later stage of the pedestrian input after the internal pressure of the airbag 20 increases as the pedestrian input continues, the frangible sewn portions 26 rupture, thereby reducing the internal pressure of the airbag 20. Therefore, in the later stage of the pedestrian input, the rebound of the airbag 20 associated with the pedestrian input can be suppressed and the impact of the pedestrian can be alleviated, thereby improving pedestrian protection performance.

[0046] Furthermore, in the airbag 20, the frangible sewn portions 26 of the outer periphery sewn portions 22 have protrusions 26a formed to protrude toward the inside of the bag. With this configuration, when the internal pressure of the airbag 20 increases due to the inflow of inflation fluid and the airbag 20 deploys and inflates, stress is more likely to concentrate on the protrusions 26a of the frangible sewn portions 26 than on the regular sewn portions 25. In particular, the protrusions 26a have bent corners 26b midway along the protrusions 26a, which further increases the likelihood of stress concentration.

[0047] Therefore, according to the airbag 20, it is possible to improve the fragility of the weak stitched portion 26, and it is possible to promote rupture of the weak stitched portion 26 when a pedestrian strikes the airbag 20 after it has been deployed and inflated.

[0048] The present invention is not limited to the above-described embodiments and modifications, and various modifications can be made without departing from the spirit of the present invention. Furthermore, this specification not only discloses the technical ideas indicated by the citation relationships set forth in the claims at the time of filing, but also discloses technical ideas obtained by appropriately combining the matters set forth in the claims. [Explanation of symbols]

[0049] 1: vehicle, 2: front pillar, 3: vehicle hood panel, 10: case, 11: opening, 12: high pressure source, 20: pedestrian protection airbag (airbag), 21, 21a, 21b: panel, 22: peripheral stitching, 23: inlet, 25: general stitching, 25a: first general stitching, 25b: second general stitching, 26: weak stitching, 26a: convex portion, 26b: corner.

Claims

1. A bag-shaped pedestrian protection airbag is stored in a folded state in a case that is disposed near a rear end of a vehicle hood panel and has an opening, and that pops out of the opening when inflation fluid flows in to cover an upper surface of a front pillar, a periphery stitched portion formed by sewing together a plurality of panels in a state in which an inlet through which the inflation fluid can flow is formed, The outer periphery stitched portion is General sewing department and a fragile sewn portion that is more easily broken than the general sewn portion; A pedestrian protection airbag having:

2. The general sewn portion has first and second general sewn portions in which stitches extend linearly and are spaced apart from each other, a vent hole portion disposed between the first general sewn portion and the second general sewn portion, the vent hole portion allowing communication between the inside and outside of the bag; The pedestrian protection airbag according to claim 1 , wherein the weakened stitching is formed so as to close the vent hole.

3. 3. The pedestrian protection airbag according to claim 2, wherein the weakened sewn portion is formed so as to connect the first general sewn portion and the second general sewn portion in a non-linear manner.

4. The pedestrian protection airbag according to claim 1 , wherein the weakened stitched portion has a protrusion formed to protrude toward the inside of the bag.

5. 5. The pedestrian protection airbag according to claim 4, wherein the protrusion has a bent corner midway through the protrusion.

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