JP2021115874A - Knee airbag and knee airbag device - Google Patents

Abstract

To provide a knee airbag and a knee airbag device that are simply configured to release internal gas to the inside of a vehicle body when inner pressure is increased.SOLUTION: A knee airbag device includes: a knee airbag 2 that can expand and deploy at the front side of the lower legs of an occupant; an inflator 3 configured to supply gas to the knee airbag 2; and a retainer housing the knee airbag 2 and the inflator 3. The knee airbag 2 includes an opening 21 through which a portion of the inflator 3 can be inserted to the inside, and the opening 21 has a diameter D2 larger than an outer diameter D1 of the inflator 3.SELECTED DRAWING: Figure 3

Description

The present invention relates to a knee airbag and a knee airbag device, and more particularly to a knee airbag and a knee airbag device capable of exhausting internal gas to the outside when the internal pressure of the knee airbag rises.

A vehicle such as an automobile may be provided with a knee airbag device for absorbing an impact generated on the lower leg (a part including the knee and the shin) of an occupant at the time of a vehicle collision. Such a knee airbag device is generally arranged on an instrument panel, which is an interior cover in front of the occupant's knee, and is configured to expand and deploy the airbag between the instrument panel and the occupant in the event of a vehicle collision.

In general, such a knee airbag device tends to have a high internal pressure for early deployment, but if the internal pressure becomes too high, the load applied to the occupant becomes high. In the field of airbags, it is common to provide vent holes to avoid excessive internal pressure. However, since the knee airbag is arranged in a narrow space under the feet of the occupant, it is not preferable to release the internal gas into the vehicle interior.

Therefore, in the invention described in Patent Document 1, a vent hole is formed in the knee airbag and a through hole is formed in the storage portion, and when the knee portion of the occupant is in a state of being close to the storage portion, the vent hole is formed. Is aligned with the through hole to exhaust the internal gas into the vehicle body.

Japanese Unexamined Patent Publication No. 2010-58605

However, in the invention described in Patent Document 1, when the vent hole and the through hole do not match, the internal gas cannot be exhausted to the outside. Therefore, there is a problem that the internal gas cannot be exhausted when the internal pressure of the knee airbag becomes high after the expansion and deployment of the knee airbag is completed.

The present invention has been devised in view of the above-mentioned problems, and provides a knee airbag and a knee airbag device capable of exhausting internal gas into a vehicle body when the internal pressure of the knee airbag rises with a simple structure. The purpose is.

According to the present invention, a knee airbag that can be expanded and deployed in front of the lower leg of an occupant and has an opening into which a part of the inflator can be inserted, and the opening is the outer diameter of the inflator. Provided is a knee airbag having a larger diameter and configured to form a gap capable of exhausting internal gas between the inflator and the opening during expansion and deployment. NS.

Further, according to the present invention, in a knee airbag device including a knee airbag that can be expanded and deployed in front of the lower leg of an occupant and an inflator that supplies gas to the knee airbag, the knee airbag is provided. , The opening is provided with an opening into which a part of the inflator can be inserted, and the opening has a diameter larger than the outer diameter of the inflator, and an internal gas is provided between the inflator and the opening during expansion and deployment. A knee airbag device is provided that is configured to form an exhaustable gap.

In the knee airbag and knee airbag device described above, the inflator includes a fixing bolt, and the opening has a diameter smaller than the total value of the outer diameter of the inflator and the length of the fixing bolt. You may be.

Further, the opening may have a size capable of inserting the fixing bolt in a deformed state when the inflator is inserted.

Further, the edge of the opening may be sutured.

Further, the opening may include a slit formed so as to communicate with the slit, and the slit may be sewn so as to break by a predetermined pressure.

According to the knee airbag and knee airbag device according to the present invention described above, the inflator and the opening are formed by forming an opening for inserting a part of the inflator into the knee airbag to be larger than the outer diameter of the inflator. A gap capable of exhausting the internal gas can be formed between the and. Therefore, according to the present invention, the internal gas can be exhausted into the vehicle body when the internal pressure of the knee airbag rises with a simple structure.

It is sectional drawing which shows the knee airbag apparatus which concerns on one Embodiment of this invention, (A) shows the state before expansion expansion, (B) shows the state after expansion expansion completion. It is a top view which shows a part of the cut parts of the base cloth which constitutes the knee airbag shown in FIG. 1, (A) shows a main panel, (B) shows a sub-panel. It is a rear view of the knee airbag alone shown in FIG. It is a figure which shows the insertion method of an inflator, (A) shows the state before insertion, (B) shows the state at the time of insertion. It is a schematic diagram which shows the exhaust state of a knee airbag. It is a figure which shows the operation of the knee airbag apparatus shown in FIG. It is a partially enlarged view which shows the modification of the knee airbag.

Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1A to 7. Here, FIG. 1 is a cross-sectional view showing a knee airbag device according to an embodiment of the present invention, in which FIG. 1A shows a state before expansion and expansion, and FIG. 1B shows a state after expansion and expansion is completed. There is. 2A and 2B are plan views showing a part of the cut parts of the base fabric constituting the knee airbag shown in FIG. 1, where FIG. 2A shows a main panel and FIG. 2B shows a subpanel. FIG. 3 is a rear view of the knee airbag alone shown in FIG. 4A and 4B are views showing a method of inserting an inflator, in which FIG. 4A shows a state before insertion and FIG. 4B shows a state at the time of insertion.

As shown in FIGS. 1 (A) to 4 (B), the knee airbag device 1 according to the embodiment of the present invention includes the knee airbag 2 that can be expanded and deployed in front of the lower leg portion M of the occupant. The knee airbag 2 includes an inflator 3 for supplying gas to the knee airbag 2 and a retainer 4 for accommodating the knee airbag 2 and the inflator 3, and the knee airbag 2 has an opening 21 into which a part of the inflator 3 can be inserted. The opening 21 has a diameter D2 larger than the outer diameter D1 of the inflator 3. In addition, in FIG. 1A and FIG. 1B, a state in which a part of the instrument panel P is cut out is shown.

The instrument panel P is a general term for all interior parts arranged in front of the front seats of a vehicle, and may be referred to as a dashboard. For example, an accelerator pedal and a brake pedal are arranged below the instrument panel P on the driver's side. When the occupant is on board, the lower leg portion M is arranged between the floor surface and the instrument panel P. The lower leg M means a portion including the knee and the shin. Although the driver's seat is shown in FIGS. 1 (A) and 1 (B) for convenience of explanation, the knee airbag device 1 can also be applied to the passenger seat.

The inflator 3 has, for example, a substantially cylindrical outer shape, and a gas outlet is formed at an end on the side to be inserted into the knee airbag 2. The inflator 3 is connected to an ECU (electronic control unit) (not shown) and is controlled based on a measured value of an acceleration sensor or the like. When the ECU detects a vehicle collision, the chemical stored inside the inflator 3 is burned to generate gas, and the gas is supplied to the knee airbag 2.

Further, the inflator 3 is provided with a fixing bolt 31 for fixing to the retainer 4, for example, as shown in FIG. 4 (A). The fixing bolt 31 is fixed to the main body of the inflator 3 by welding or the like in a state of being erected perpendicular to the axial direction of the inflator 3. Further, although not shown, a diffuser forming a gas flow path may be connected to the gas outlet of the inflator 3.

The inflator 3 and the knee airbag 2 are housed and fixed in a box-shaped retainer 4, for example, as shown in FIG. 1 (A). For convenience of explanation, the folded state of the knee airbag 2 is painted in gray and displayed. The retainer 4 is fixed to the vehicle interior structure arranged in the instrument panel P via a bracket or the like. Further, although not shown, the instrument panel P located on the front surface of the retainer 4 may be formed with a thin portion (tea line) for opening the instrument panel P when the knee airbag 2 is expanded and deployed.

The bag body constituting the knee airbag 2 includes a main panel 22 forming an outer shell shown in FIG. 2 (A), a sub panel 23 arranged inside the main panel 22 shown in FIG. 2 (B), and the like. Consists of. The main panel 22 is composed of, for example, a single base cloth including a front main panel 22f arranged on the occupant side and a rear main panel 22r arranged on the instrument panel P side. The main panel 22 is folded back along the fold line L, and is formed in a bag shape by suturing the edges of the folded portions.

A hole 22a forming an opening 21 into which the inflator 3 is inserted is formed in the lower portion of the rear main panel 22r. The hole 22a has, for example, a circular shape, but may have an elliptical shape or a rectangular shape as long as it has a predetermined opening area. Further, a through hole 22h through which a fixing bolt 31 fixed to the inflator 3 is inserted is formed at a position adjacent to the hole 22a.

Further, as shown in FIG. 1B, a tether 24 connecting the front main panel 22f and the rear main panel 22r is sewn to the central portion of the front main panel 22f and the rear main panel 22r. The tether 24 is formed with an opening 24a forming a flow path through which the gas supplied from the inflator 3 flows. The arrangement and number of tethers 24 are arbitrary and are not limited to the shapes shown.

Further, the shapes of the front main panel 22f and the rear main panel 22r are not limited to the shapes shown in the drawings. The shapes of the front main panel 22f and the rear main panel 22r can be arbitrarily set. For example, the illustrated main panel 22 is asymmetrical, but may be formed symmetrically. Further, the front main panel 22f and the rear main panel 22r may be composed of two separate base fabrics.

The sub-panel 23 is composed of, for example, a single base cloth including a front sub-panel 23f arranged on the occupant side and a rear sub-panel 23r arranged on the instrument panel P side. The front sub-panel 23f is arranged inside the front main panel 22f of the main panel 22, and the rear sub-panel 23r is arranged inside the rear main panel 22r of the main panel 22.

The sub-panel 23 is a base cloth that reinforces the main panel 22, and has a shape that approximates the outer shape of the main panel 22. Further, the sub-panel 23 may be formed with a notch 23k for reducing the weight and folding volume of the knee airbag 2. The sub-panel 23 is folded back along the fold line L while being placed on the main panel 22, and the edge portion is sewn together with the main panel 22. The tether 24 is also sewn to the sub panel 23 together with the main panel 22.

Similar to the rear main panel 22r, a hole 23a for forming the opening 21 and a through hole 23h for inserting the fixing bolt 31 are formed in the lower portion of the rear sub panel 23r. The holes 23a and the through holes 23h are formed so as to coincide with the holes 22a and the through holes 22h, respectively, when the main panel 22 and the sub panel 23 are sewn together.

Further, although not shown, the main panel 22 or the sub panel 23 may include a protective sheet arranged around the inflator 3. The protective sheet is a sheet for protecting each panel from high heat during use of the inflator 3. The protective sheet includes a hole for forming the opening 21 and a through hole for inserting the fixing bolt 31. When the protective sheet is used, since there are a plurality of holes forming the opening 21, the edges of the holes forming the opening 21 may be sewn as needed. With such a configuration, the inflator 3 can be easily inserted.

Here, in the rear view shown in FIG. 3, the main panel 22 and the sub panel 23 are sewn together to prepare a knee airbag 2 which is a bag body, and the rear main panel 22r is turned upside down and developed in a plane. For convenience of explanation, the inflator 3 is shown by a dotted line. The inflator 3 includes a first end portion 3a having a gas outlet and a second end portion 3b to which a harness is connected.

As shown, the first end portion 3a of the inflator 3 is inserted into the opening 21 of the knee airbag 2, and the second end portion 3b is exposed to the outside from the opening 21. At this time, the diameter D2 of the opening 21 is formed to be larger than the outer diameter D1 of the inflator 3.

Conventionally, in the knee airbag 2 in which the second end portion 3b of the inflator 3 is exposed to the outside, it is necessary to instantly increase the internal pressure in order to deploy the knee airbag 2 at an early stage. There was a stereotype that certain openings 21 had to be sealed.

On the other hand, if the internal pressure of the knee airbag 2 is too high, there is a problem that the load applied to the occupant becomes high. Therefore, as with other airbags, it is conceivable to arrange a vent hole to exhaust the internal gas. However, since the knee airbag 2 is arranged in a narrow space under the feet of the occupant, it is not preferable to release the internal gas into the vehicle interior.

Therefore, as a result of diligent studies, the present inventors have broken down the conventional stereotype and made the opening 21 which is the insertion port of the inflator 3 not sealed, but conversely, the internal gas leaks. , I came up with the idea that it is possible to achieve both the early deployment of the knee airbag 2 and the suppression of the increase in internal pressure.

As shown in FIG. 4A, where the length of the fixing bolt 31 is H, the diameter D2 of the opening 21 is larger than the outer diameter D1 of the inflator 3, and is fixed to the outer diameter D1 of the inflator 3. It is set within a range smaller than the total value (D1 + H) with the length H of the bolt 31. The specific numerical value of the opening 21 can be arbitrarily set according to conditions such as the capacity of the knee airbag 2 and the amount of the inflator 3.

When inserting the fixing bolt 31 fixed to the inflator 3 into the opening 21, for example, as shown in FIG. 4B, the base cloth constituting the knee airbag 2 is pulled to open the opening 21. Change the shape. That is, the opening 21 has a size that allows the fixing bolt 31 to be inserted in a deformed state when the inflator 3 is inserted.

Here, FIG. 5 is a schematic view showing an exhaust state of the knee airbag. For convenience of explanation, the state in which the retainer 4 is transparent is shown. As shown, the second end portion 3b of the inflator 3 is in a state of protruding from the knee airbag 2. The retainer 4 includes an opening 4a that allows the second end 3b of the inflator 3 to be exposed. By exposing the second end 3b of the inflator 3 from the opening 4a, the harness can be easily connected to the second end 3b.

Further, the retainer 4 includes, for example, a bottom surface portion 41 provided with elongated holes 4b for fixing the fixing bolts 31 of the inflator 3, a pair of side surface portions 42 arranged in the thickness direction of the knee airbag 2. It includes a pair of end face portions 43 arranged in the lateral width direction of the knee airbag 2. The opening 4a is formed in the end face portion 43 located on the second end portion 3b side of the inflator 3. The opening 4a has a shape that is long in the depth direction of the retainer 4, and has a shape that can secure a certain space at a position adjacent to the inflator 3 in a state where the inflator 3 is fixed to the retainer 4. There is.

Since the diameter D2 of the opening 21 formed in the knee airbag 2 is formed to be larger than the outer diameter D1 of the inflator 3, as shown in FIG. 5, the inflator 3 is formed when the knee airbag 2 is expanded and deployed. A gap G capable of exhausting the internal gas is formed between the opening 21 and the opening 21. Further, since the retainer 4 is formed with an opening 4a having a sufficient size, as shown by an arrow in the figure, the internal gas exhausted from the knee airbag 2 is not hindered by the retainer. It is exhausted to the outside of 4, that is, the inside of the instrument panel P.

Therefore, according to the knee airbag device 1 and the knee airbag 2 according to the present embodiment, the opening 21 for inserting a part of the inflator 3 into the knee airbag 2 is formed larger than the outer diameter D1 of the inflator 3. By doing so, a gap G capable of exhausting the internal gas can be formed between the inflator 3 and the opening 21, and the internal gas can be exhausted into the vehicle body when the internal pressure of the knee airbag 2 rises with a simple structure. Can be done.

Here, FIG. 6 is a diagram showing the operation of the knee airbag device shown in FIG. The horizontal axis represents time (ms), and the vertical axis represents the load (N) applied to the occupant by the knee airbag 2. Further, in the figure, the solid line shows the data of this embodiment, and the alternate long and short dash line shows the data of the comparative example (the one in which the insertion port of the inflator is sealed).

As shown in FIG. 6, in the data of the comparative example, gas is supplied from the inflator 3 to the inside of the knee airbag 2 at time t1, the load shows the maximum value Fp at time t2, and then the load is reduced. On the other hand, in the data of the present embodiment, gas is supplied from the inflator 3 to the inside of the knee airbag 2 at time t1, the load shows the maximum value Fi at time t3, and then the load is reduced.

As shown in the figure, in the data of the present embodiment, the load is reduced to about 70% at the time t2 when the load of the comparative example shows the maximum value Fp. Further, the maximum load value Fi in the present embodiment is also reduced to about 70% with respect to the maximum value Fp in the comparative example. Therefore, the knee airbag 2 according to the present embodiment can reduce the load applied to the occupant while exhibiting substantially the same deployment behavior as the knee airbag of the comparative example.

Next, a modified example of the knee airbag 2 according to the present embodiment will be described with reference to FIG. 7. Here, FIG. 7 is a partially enlarged view showing a modified example of the knee airbag. The same components as those in the above-described embodiment are designated by the same reference numerals, and duplicate description will be omitted.

In the modified example shown in FIG. 7, the opening 21 is provided with a slit 25 formed so as to be able to communicate with the slit 25, and the slit 25 is sewn so as to be broken by a predetermined pressure. The slit 25 is sutured after inserting the inflator 3 into the opening 21.

According to this configuration, the gap G between the inflator 3 and the opening 21 can be kept small until the knee airbag 2 reaches a predetermined internal pressure, and gas leakage at the initial stage of expansion and deployment can be minimized. Can be suppressed. Then, when the knee airbag 2 reaches a predetermined internal pressure, the suture thread that sews the slit 25 is broken, the gap G between the inflator 3 and the opening 21 can be increased, and the internal gas is exhausted from the opening 21. be able to.

It goes without saying that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

1 Knee airbag device 2 Knee airbag 3 Inflator 3a First end 3b Second end 4 Retainer 4a Opening 4b Long hole 21 Opening 22 Main panel 22a Hole 22f Front main panel 22h Through hole 22r Rear main panel 23 Sub panel 23a Hole 23f Front subpanel 23h Through hole 23k Notch 23r Rear subpanel 24 Tether 24a Opening 25 Slit 31 Fixing bolt 41 Bottom part 42 Side part 43 End face part

Claims (6)

A knee airbag that can be expanded and deployed in front of the occupant's lower leg.
It has an opening into which a part of the inflator can be inserted, and the opening has a diameter larger than the outer diameter of the inflator, and exhausts internal gas between the inflator and the opening during expansion and deployment. It is configured to form a possible gap,
A knee airbag that features that. The knee airbag according to claim 1, wherein the inflator includes a fixing bolt, and the opening has a diameter smaller than the total value of the outer diameter of the inflator and the length of the fixing bolt. The knee airbag according to claim 2, wherein the opening has a size capable of inserting the fixing bolt in a deformed state when the inflator is inserted. The knee airbag according to claim 1, wherein the opening has a sewn edge. The knee airbag according to claim 1, wherein the opening includes a slit formed so as to communicate with the slit, and the slit is sewn so as to break by a predetermined pressure. In a knee airbag device equipped with a knee airbag that can be expanded and deployed in front of the lower leg of an occupant, an inflator that supplies gas to the knee airbag, and a knee airbag device.
The knee airbag device, wherein the knee airbag is the knee airbag according to any one of claims 1 to 5.

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