JP2017144840A - Knee airbag device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a knee air bag device capable of suppressing an operation in which, both knee parts of an occupant are opened outward during inflation and expansion of a knee airbag, with a simple structure.SOLUTION: A knee airbag device 1 comprises: a knee airbag 10 for restricting both knees of an occupant by inflating and expanding by reception of gas supply; and an upper tether 21 for regulating inflation and expansion of the knee airbag 10. The upper tether 21 is formed into a long belt-like shape extending in a longitudinal direction D3, jointed to an inner wall of the knee airbag 10 on both end parts 22, 23 of a width direction D2 orthogonal to the longitudinal direction D3, and has a recessed part 22a which becomes dent in the width direction D2 on the end part 22. The upper tether is provided on a vehicle rear side so that the upper tether extends in a vehicle lateral direction as the longitudinal direction D3 in inflation and expansion of the knee airbag 10, and the recessed part 22a faces both knee parts K, K of the occupant.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a knee airbag device mounted on a vehicle.

  Conventionally, various airbag devices mounted on vehicles for protecting passengers have been proposed. For example, Patent Literature 1 below discloses a knee airbag device including a knee airbag that is inflated and deployed to restrain both knee portions of an occupant. In this knee airbag device, the knee airbag is configured such that the bag thickness at both ends at the time of inflation and deployment is thicker than the center portion. In this case, by restraining the occupant's knees at both ends of the knee airbag, an attempt is made to suppress the so-called “crotch opening” operation in which the occupant's knees open outward.

JP 2008-126974 A

However, in the knee airbag device described above, the central portion of the knee airbag that inflates and deploys in the space between the occupant's knees has a larger volume than both ends, and both knees are exposed to the outside by the central part. It is easy to be pressed. For this reason, even if only the structure of increasing the bag thickness at both ends of the knee airbag is employed, it is difficult to essentially suppress the occupant's crotch opening. As a result of the crotch opening, the amount of lifting of the occupant's waist (waist stroke) increases, and the occupant's head tends to approach the windshield.
Therefore, when designing this type of knee airbag device, there is a demand for a technique that can reliably suppress the occupant's crotch opening in order to protect the occupant. In that case, it is preferable to adopt a simple structure that does not complicate the knee airbag device.

  The present invention has been made in view of such a problem, and an object of the present invention is to provide a knee airbag device capable of suppressing an operation of opening both knee portions of an occupant outward when a knee airbag is inflated and deployed with a simple structure. Is.

One aspect of the present invention is a knee airbag device mounted on a vehicle,
A knee airbag that receives gas supply and inflates and deploys to restrain both occupants'knees;
A tether that regulates inflation and deployment of the knee airbag,
The tether has a long strip shape extending in the longitudinal direction, and is joined to the inner wall of the knee airbag at both ends in the width direction perpendicular to the longitudinal direction, and at least one of the both ends A recessed portion recessed in the width direction, extending in the vehicle lateral direction as the longitudinal direction when the knee airbag is inflated and deployed, and on the vehicle rear side so that the recessed portion faces both knees of the occupant Located in the knee airbag device.

  In this knee airbag device, the joint portion of the knee airbag that is joined to the tether recess is recessed in the front side of the vehicle when inflated and deployed, that is, separated from both knees of the occupant. Opposite the part. And this joint part expand | swells toward the space between a passenger | crew's both knee parts. For this reason, in the knee airbag, the inflated volume at the joint that inflates toward the space between the knee portions of the occupant can be kept small. As a result, the knee airbag of the occupant is hardly pushed left and right by the inflated and deployed knee airbag, and the operation of opening both knees outward is suppressed. In this case, it is possible to cope with a simple structure by devising only the configuration of the tether without changing the configuration of the knee airbag.

  As described above, according to the knee airbag device described above, it is possible to suppress the movement of the knees of the occupant to the outside when the knee airbag is inflated and deployed with a simple structure.

FIG. 3 is a diagram illustrating an outline of a configuration of a knee airbag device according to the first embodiment. The top view which looked at the knee airbag after the expansion | deployment in FIG. 1 from the arrow A direction. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. FIG. 4 is a sectional view taken along line IV-IV in FIG. 3. FIG. 5 is a cross-sectional view taken along line V-V in FIG. 3. The top view of the upper tether in FIG. The figure for demonstrating the dimension setting of an upper tether in FIG. The top view of the lower tether in FIG. The figure which shows the mode of the knee airbag after inflate-deployment about the cross section in FIG. The figure for demonstrating the gas flow formed at the time of inflation expansion | deployment of a knee airbag in FIG. FIG. 6 is a plan view of an upper tether in the second embodiment. FIG. 9 is a plan view of an upper tether in Embodiment 3. FIG. 10 is a plan view of an upper tether in the fourth embodiment.

  In the present embodiment, “inflation and deployment” refers to an operation in which an airbag that has been folded in a predetermined form in advance is deployed so as to release the folded state while being inflated by receiving supply of gas. “Restraining” includes a mode in which the movement of both knees of the occupant to the front of the vehicle is received by the reaction force due to the internal pressure of the knee airbag, and the movement of both laps of the occupant outward (also referred to as “crotch opening”). The aspect which regulates by a knee airbag is included.

In the knee airbag device according to the aspect described above, the tether has a first imaginary path in which one open end of the recessed portion passes through the center of one knee of the occupant in the width direction when the knee airbag is inflated and deployed. It is preferable that the other open end of the recess is disposed on a second imaginary line passing through the center of the other knee of the occupant in the width direction.
In this configuration, the joint portion of the knee airbag that is joined to the outer region from the open end of the tether recess is disposed at a position close to both knees of the occupant. Therefore, the movement of the occupant's knees in the initial stage of inflating and expanding can be received by the reaction force due to the internal pressure at the joint. For this reason, in addition to the effect of suppressing the movement of both the knees of the occupant to the outside, both the knees of the occupant trying to move forward in the vehicle can be quickly restrained in the initial stage of inflation and deployment of the knee airbag. . As a result, it is possible to improve occupant restraint in the initial stage of inflation and deployment of the knee airbag.

In the knee airbag device of the above aspect, it is preferable that the tether is configured such that the opening width in the longitudinal direction of the recess is gradually narrowed toward the bottom surface.
According to this structure, compared with the case where the opening width of a recessed part is constant, stress becomes difficult to concentrate on the junction part to which the tether is joined among knee airbags. For this reason, durability of a knee airbag can be improved.

In the knee airbag device according to the aspect described above, it is preferable that the tether includes the concave portion at a symmetrical position in the width direction of both the end portions. In this case, the tether has a recess at one end joined to one panel surface in the thickness direction of the knee airbag, and a recess at the other end contacts the other panel surface in the thickness direction of the knee airbag. Be joined.
This makes it possible to inflate and deploy both panel surfaces of the knee airbag in a balanced manner in the thickness direction. Further, the tether has a symmetric shape, and the manufacturing cost can be reduced as compared with a tether having a recess at only one end.

In the knee airbag device of the above aspect, the tether includes a narrow portion having a relatively narrow tether width in the width direction at the both end portions, and the concave portion is configured using the narrow portion. It is preferable.
According to this configuration, the airbag thickness at the joint portion of the knee airbag with the tether recess, that is, the airbag thickness at the portion facing the space between the knee portions of the occupant can be kept small. As a result, the internal pressure at the joint is less likely to decrease, and the reaction force for restraining the occupant's knees can be maintained high.

Moreover, in the knee airbag device of the above aspect, the tether includes a plurality of gas circulation openings, and the gas distribution opening located in the vicinity of the recessed portion among the plurality of gas circulation openings has a different gas distribution area. It is preferable to be configured to be smaller than the opening area of the opening.
According to this structure, gas can be appropriately distribute | circulated through the some gas distribution opening between the chambers divided by the tether. Moreover, it can suppress that the gas distribution opening located in the vicinity of a dent part expands, and a dent part expand | extends to a passenger | crew side.

In the knee airbag device of the above aspect, when the tether is an upper tether, a lower tether joined to the inner wall of the knee airbag and having a gas flow opening is provided separately from the upper tether. The knee airbag is disposed below the upper tether when the knee airbag is inflated and deployed. The knee airbag is formed below the lower tether and is first supplied with the gas; and the lower tether And a second chamber formed between the upper tether and a third chamber formed above the upper tether.
According to this configuration, since the three chambers are sequentially inflated from the lower chamber when the knee airbag is inflated and deployed, the restraining force that restrains both knee portions of the occupant increases stepwise. Accordingly, both knee portions of the occupant can be reliably restrained from the initial stage of the inflation and deployment of the knee airbag, and the occupant restraint property is improved.

  Hereinafter, the airbag apparatus of this embodiment is demonstrated, referring drawings.

  In the drawings of this specification, the front side of the vehicle is indicated by an arrow X, and the upper side of the vehicle is indicated by an arrow Y. In addition, unless otherwise specified, the air bag is in the vertical direction during inflation and deployment and the thickness direction of the tether is indicated by an arrow D1, the thickness direction of the airbag is inflated and deployed and the width direction of the tether is indicated by an arrow D2. The direction orthogonal to both the first direction D1 and the second direction D2 is indicated by an arrow D3. In this case, the direction indicated by the arrow D3 is the left-right direction of the airbag at the time of inflation and deployment and the longitudinal direction of the tether.

(Embodiment 1)
As shown in FIG. 1, the knee airbag device 1 according to the first embodiment is mounted on a vehicle 100, and is particularly configured to be mounted on an interior member 101 of the vehicle 100. The knee airbag device 1 includes a knee airbag (hereinafter also simply referred to as “airbag”) 10, a tether 20, and an inflator 30. The knee airbag device 1 is provided for an occupant C sitting on a driver seat 104.

  The collision detection sensor 102 is configured to detect a collision of the vehicle 100. The control unit (ECU) 103 is configured to output a control signal to the knee airbag device 1 when the collision detection sensor 102 detects a collision of the vehicle 100. Both the collision detection sensor 102 and the control unit 103 are mounted on the vehicle 100, and together with the knee airbag device 1, an occupant protection system for protecting the occupant is constructed.

  The airbag 10 is formed into a bag shape by stitching a plurality of base fabrics, and is accommodated in a container together with the inflator 30 in a state of being folded in a predetermined form in advance. The inflator 30 is a gas supply unit that supplies gas to the airbag 10, and is configured to be operated by a control signal from the control unit 103 to generate gas.

  The gas generated in the inflator 30 is supplied to the internal space of the airbag 10. At this time, the airbag 10 is inflated and deployed in the front region of both knee portions K of the occupant C while receiving the supply of gas from the inflator 30 and protruding from the interior member 101 toward the passenger compartment space. That is, the airbag 10 folded in a predetermined form in advance performs an operation of deploying so as to release the folded state while being inflated. At this time, the tether 20 is joined to the airbag 10 as a tether, and is configured to regulate the inflation and deployment of the airbag 10. The inflated airbag 10 functions to restrain at least both knees K of the occupant C. The restraint here refers to an aspect in which the movement of both knees K of the occupant C moving forward by the reaction force due to the internal pressure of the airbag 10 and the movement of both knees K of the occupant C to open outwards. A mode to regulate is included.

  As shown in FIGS. 2 and 3, in this embodiment, two upper tethers 21 and lower tethers 27 are used as the tethers 20. An upper tether 21 and a lower tether 27 are joined to an inner wall (bag inner wall) 10 a of the airbag 10. Thus, the airbag 10 is tethered from the inside by the tethers 21 and 27 so as not to be inflated and deployed beyond a certain size. Each of the tethers 21 and 27 has a long strip shape (also referred to as “belt shape” or “thin plate shape”) extending in the longitudinal direction D3 with a uniform thickness. The lower tether 27 is configured to be disposed below the upper tether 21 in the vertical direction D1 when the airbag 10 is inflated and deployed.

  The tethers 21 and 27 are typically joined to the inner wall of the airbag 10 by a technique such as stitching or adhesion. The tethers 21 and 27 are typically formed of a base fabric used for the airbag 10 or a webbing material used for a seat belt.

  The airbag 10 is configured such that an internal space at the time of inflation and deployment is partitioned into three chambers 11, 12, and 13 by two tethers 21 and 27. The first chamber 11 is a space formed below the lower tether 27 in the up-down direction D1 of the airbag 10 and to which gas from the inflator 30 is first supplied. The second chamber 12 is a space formed between the upper tether 21 and the lower tether 27 in the up-down direction D1 of the airbag 10. The third chamber 13 is a space formed above the upper tether 21 in the up-down direction D1 of the airbag 10.

  As shown in FIG. 4, the upper tether 21 is joined to the inner wall 10a of the airbag 10 at both end portions 22 and 23 in the width direction D2 orthogonal to the longitudinal direction D3. The upper tether 21 is configured to extend with the vehicle left-right direction (vehicle width direction) as a longitudinal direction D3 when the airbag 10 is inflated and deployed. In this upper tether 21, one end (long side) 22 is provided with a recess 22a, and the other end (long side) 23 is provided with a recess 23a having the same shape as the recess 22a. ing. Each of the recesses 22a and 23a is a part where both end parts 22 and 23 are recessed in the width direction D2 (a notch-like part in which a part of the end part is notched). In addition, the upper tether 21 is configured to include the recessed portions 22a and 23a at the symmetrical positions in the width direction D2 of both the end portions 22 and 23. The “symmetrical position in the width direction D2” here can also be referred to as a position facing each other in the width direction D2 or a position in line symmetry with respect to a symmetry axis extending in the longitudinal direction D3.

  The upper tether 21 is provided with a plurality of gas distribution openings 21a, 21b, 21c arranged in the longitudinal direction D3, and gas can be distributed through the plurality of gas distribution openings 21a, 21b, 21c. Thereby, gas can be appropriately circulated through the plurality of gas circulation openings 21a, 21b, and 21c between the second chamber 12 and the third chamber 13 partitioned by the upper tether 21.

  The gas flow opening 21 a is a through hole provided in the central portion of the upper tether 21 in the longitudinal direction D3. This gas circulation opening 21a is disposed so as to be positioned closest to the recess 22a as compared with the other gas circulation openings 21b and 21c. The gas flow opening 21a has an elliptical shape in which the width direction D2 of the upper tether 21 is short and the long direction D3 is long. The gas circulation opening 21b is a through hole provided on both sides of the gas circulation opening 21a, and has an elliptical shape like the gas circulation opening 21a. Moreover, it is comprised so that the opening area (flow-path area) of the gas distribution opening 21a may be less than the opening area (flow-path area) of the gas distribution opening 21b which is another gas distribution opening. The gas flow openings 21c are semi-elliptical grooves provided outside the gas flow openings 21b. The gas circulation opening 21c and the inner wall of the airbag 10 define a space through which gas can flow.

  As shown in FIG. 5, the lower tether 27 is joined to the inner wall 10 a of the airbag 10 at both end portions 28 and 29 in the width direction D2 similarly to the upper tether 21. The lower tether 27 is configured to extend with the vehicle left-right direction (vehicle width direction) as a longitudinal direction D3 when the airbag 10 is inflated and deployed.

  The lower tether 27 is provided with a plurality of gas circulation openings 27a, 27b, 27c arranged in the longitudinal direction D3 in the same shape as the gas circulation openings 21a, 21b, 21c provided in the upper tether 21. Yes. Gas can be distributed through the plurality of gas distribution openings 27a, 27b, and 27c. Thereby, gas can be appropriately distributed between the first chamber 11 and the second chamber 12 partitioned by the lower tether 27 through the plurality of gas distribution openings 27a, 27b, and 27c.

  The gas supplied from the inflator 30 is first filled in the first chamber 11 in the internal space of the airbag 10. Thereby, the airbag 10 starts inflating and deploying. This gas flows into the second chamber 12 through the plurality of gas flow openings 27a, 27b, and 27c of the lower tether 27 while filling the first chamber 11. This gas further flows into the third chamber 13 through the plurality of gas flow openings 21 a, 21 b, 21 c of the upper tether 21 while being filled in the second chamber 12. The third chamber 13 is filled with gas until the airbag 10 is inflated and deployed in a predetermined state.

  As shown in FIG. 6, the upper tether 21 has a line-symmetric shape in both the width direction D2 and the longitudinal direction D3. That is, the upper tether 21 is line symmetric with respect to the center line (symmetric axis) extending in the width direction D2, and is line symmetric with respect to the center line (symmetric axis) extending in the longitudinal direction D3. The upper tether 21 includes a narrow portion 24 at the center in the longitudinal direction D3, and includes wide portions 25 at both ends in the longitudinal direction D3. The narrow portion 24 is a portion where the tether width in the width direction D2 of the both end portions 22 and 23 is relatively narrow. The narrow portion 24 has a tether width d1 (<d2) that is less than the tether width d2 of the wide portion 25. A gas flow opening 21 a is provided in the narrow portion 24, and a gas flow opening 21 c is provided in the wide portion 25.

  In the upper tether 21, a gradual change portion 26 is provided between the narrow portion 24 and the wide portion 25. The gradual change portion 26 is provided with a gas flow opening 21b. The width dimension of the upper tether 21 in the width direction D2 gradually changes between the tether width d1 and the tether width d2 in the gradually changing portion 26. In this case, the narrow portion 24 of the upper tether 21 is used, and in particular, the concave portion 22a is configured by both the narrow portion 24 and the gradually changing portion 26. Therefore, the recess 22a of the upper tether 21 has an opening width in the longitudinal direction D3 (an opening width d3 between one opening end 22b and the other opening end 22c) from the gradually changing portion 26 toward the narrow portion 24. It is configured so as to become gradually narrower as it becomes narrower at the bottom surface 22d of the narrow portion 24.

  As shown in FIG. 7, the upper tether 21 is configured to be disposed on the vehicle rear side so that the recessed portion 22a faces both knees K, K of the occupant C when the airbag 10 is inflated and deployed. Has been. Further, when the airbag 10 is inflated and deployed, the upper tether 21 has a recess 22a on the first imaginary line L1 that is a straight line that passes through the center of one knee K of the occupant C and extends in the width direction D2. One open end 22b is disposed, and the other open end 22c of the recessed portion 22a is disposed on the second imaginary line L2, which is a straight line passing through the center of the other knee K of the occupant C and extending in the width direction D2. It is configured to be. In this case, both the first virtual line L1 and the second virtual line L2 are boundary lines between the wide portion 25 and the gradually changing portion 26. Here, the center of the knee portion K refers to an intermediate portion in the knee width direction of the knee portion K (intermediate portion between the inner side and the outer side of the knee portion K).

  Further, when the airbag 10 is inflated and deployed, the upper tether 21 has a recess 22a on the third imaginary line L3 that is a straight line that passes through the inside of one knee K of the occupant C and extends in the width direction D2. One end 22e of the bottom surface 22d is disposed, and the other end 22f of the bottom surface 22d of the recess 22a is on a fourth imaginary line L4 that is a straight line passing through the inside of the other knee K of the occupant C and extending in the width direction D2. It is configured to be arranged.

  When the airbag 10 is inflated and deployed, the narrow portion 24 of the upper tether 21 is disposed in a region between the third virtual line L3 and the fourth virtual line L4. Further, the wide portion 25 of the upper tether 21 is arranged in a region outside the first virtual line L1 and a region outside the second virtual line L2. Further, the gradual change portion 26 of the upper tether 21 is disposed in a region between the first virtual line L1 and the third virtual line L3 and a region between the second virtual line L2 and the fourth virtual line L4. .

  As shown in FIG. 8, unlike the upper tether 21, the lower tether 27 is configured such that the tether width in the width direction D2 is constant. The lower tether 27 has a tether width d 4 that is wider than the narrow portion 24 of the upper tether 21 and narrower than the wide portion 25.

  As shown in FIG. 9, the airbag 10 includes a first joint portion 14, a second joint portion 15, and a third joint portion 16 in a back panel 10 b disposed on the vehicle rear side after deployment. It is configured as follows.

  The first joint portion 14 is a joint portion in which the rear panel 10 b of the airbag 10 is joined to a region corresponding to the narrow portion 24 in the end portion 22 of the upper tether 21. This first joint portion 14 is a central portion in the longitudinal direction D3 of the back panel 10b, and when the airbag 10 is inflated and deployed, the inside of one knee portion K of the occupant C and the inside of the other knee portion K. (The region between the third virtual line L3 and the fourth virtual line L4 in FIG. 7).

  The second joint 15 is a joint where the rear panel 10 b of the airbag 10 is joined to a region corresponding to the wide portion 25 in the end 22 of the upper tether 21. The second joint portions 15 are both end portions in the longitudinal direction D3 of the back panel 10b, and are regions outside the center of each knee portion K of the occupant C when the airbag 10 is inflated and deployed (in FIG. 7). In the region outside the first virtual line L1 and the region outside the second virtual line L2.

  The third joint portion 16 is a joint portion in which the rear panel 10 b of the airbag 10 is joined to a region corresponding to the gradually changing portion 26 in the end portion 22 of the upper tether 21. This 3rd junction part 16 is a site | part between the 1st junction part 14 and the 2nd junction part 15, and the area | region (in FIG. 7) between the inner side and center of each knee part K of the passenger | crew C In the region between the first virtual line L1 and the third virtual line L3 and the region between the second virtual line L2 and the fourth virtual line L4).

  Next, the effect of the knee airbag device 1 of Embodiment 1 will be described with reference to FIGS. 9 and 10.

  When the gas generated when the inflator 30 is operated is supplied to the internal space of the airbag 10, the airbag 10 is inflated and deployed in the front region of the knee K of the occupant C. At this time, as shown in FIG. 9, the joining portions 14 and 16 joined to the recessed portion 22 a of the upper tether 21 in the rear panel 10 b of the airbag 10 are recessed in the front side of the vehicle when inflated and deployed. It faces the knees K, K of the occupant C. In this case, the joint portions 14 and 16 are disposed at a position farther from the knee portion K than the joint portion 15. And the back panel 10b expand | swells toward the space S between both knee parts K and K of the passenger | crew C in the junction parts 14 and 16. FIG. For this reason, the airbag 10 has a small inflated volume that expands toward the space S between the knee portions K, K of the occupant C.

  As a result, the inflated airbag 10 makes it difficult for the knees K, K of the occupant C to be pushed to the left and right, and the movement of the knees K, K to open outward (crotch opening) can be suppressed. In this case, it is possible to cope with a simple structure by devising only the configuration of the upper tether 21 without changing the configuration of the airbag 10. Accordingly, it is possible to suppress the movement of the knees K, K of the occupant C to open outward when the airbag 10 is inflated and deployed with a simple structure. At this time, while allowing the occupant C to open the crotch, the amount of movement of the knees K, K to the outside can be reduced. Further, by suppressing the occupant C from opening the crotch, it is possible to suppress the occupant C's hip lifting amount (waist stroke), and to reduce the possibility that the head of the occupant C is close to the windshield.

  In the present embodiment, since the wide portion 25 is provided in the upper tether 21, the airbag thickness at both ends corresponding to the joint 15 in the airbag 10 (portions outside the center of each knee K). That is, the expansion volume can be increased. Thereby, the effect which suppresses the passenger | crew's C crotch opening can be made more reliable.

  Further, in the airbag 10, the joint portion 15 joined to the outer region than the opening ends 22 b and 22 c of the recess portion 22 a of the upper tether 21 has both knee portions K of the occupant C more than the other joint portions 14 and 16. , K. As a result, the movement of the knees K, K of the occupant C moving forward in the initial stage of inflation and deployment can be received by the reaction force due to the internal pressure at the joint 15. For this reason, in addition to the effect of suppressing the movement of the knees K, K of the occupant C outward, the knees K, K of the occupant C trying to move forward in the initial stage of inflation and deployment of the airbag 10 Can be restrained promptly. As a result, the occupant restraint performance at the initial stage of the inflation and deployment of the airbag 10 can be improved.

  Further, the upper tether 21 is configured such that the opening width in the longitudinal direction D3 of the recessed portion 22a gradually becomes narrower toward the bottom surface 22d, compared to a case where the opening width of the recessed portion 22a is constant. In the airbag 10, stress is less likely to concentrate on the joint portion 16 to which the upper tether 21 is joined. For this reason, the durability of the airbag 10 can be improved.

  In the present embodiment, the upper tether 21 has a recess 22a at one end 22 joined to one panel surface in the thickness direction of the airbag 10, and a recess 23a at the other end 23 is an airbag. It is comprised so that it may join to the other panel surface of 10 thickness directions. Thereby, both panel surfaces of the airbag 10 can be inflated and deployed with good balance in the thickness direction. Further, the upper tether 21 has a symmetrical shape, and the manufacturing cost can be reduced as compared with a tether provided with a recess 22a only on one end 22 thereof.

  Moreover, in this embodiment, the recessed part 22a of the upper tether 21 is comprised using the narrow part 24, and the air in the junction parts 14 and 16 with the recessed part 22a of the upper tether 21 among the airbags 10 is comprised. The bag thickness, that is, the airbag thickness at the portion facing the space S between the knee portions K, K of the occupant C can be kept small. Thereby, the internal pressure at the joint portions 14 and 16 is unlikely to decrease, and the reaction force for restraining the knee portions K and K of the occupant C can be maintained high.

  Further, in the present embodiment, since the opening area of the gas circulation opening 21a located in the vicinity of the recess 22a of the upper tether 21 is smaller than the opening area of the other gas circulation openings 21b and 21c, the gas circulation opening 21a is expanded. It can suppress that the recessed part 22a extends to the passenger | crew C side.

  In the present embodiment, the gas flow opening 21a has an elliptical shape in which the width direction D2 of the upper tether 21 is the short side and the long direction D3 is the long side, and is difficult to expand in the width direction D2. As the shape of the gas flow opening 21a, for example, a shape such as a circle or a polygon may be adopted.

  As shown in FIG. 10, when the airbag 10 is inflated and deployed, the three chambers 11, 12, and 13 are inflated sequentially from the lower chamber. That is, the first chamber 11 is first expanded by the gas flow F <b> 1 from the inflator 30. Next, the second chamber 12 is expanded by the gas flow F <b> 2 from the first chamber 11. Finally, the third chamber 13 is expanded by the gas flow F3 from the second chamber 11. In this case, the restraining force that restrains both knees K, K of the occupant C increases stepwise. Thereby, both knee parts K and K of the passenger | crew C can be restrained reliably from the initial stage of the expansion | deployment of the airbag 10, and passenger | crew restraint property improves.

The shape of the upper tether 21 can be changed as necessary. For example, the following Embodiments 2 to 4 can be adopted.
The second to fourth embodiments are different from the first embodiment only in the configuration of the upper tether. Other configurations are the same as those of the first embodiment. Here, only the configuration of the upper tether according to the modified example will be described with reference to FIGS. 11 to 13, and description of other elements will be omitted. 11 to 13, the same elements as those shown in FIG. 6 are denoted by the same reference numerals.

(Embodiment 2)
The upper tether 121 in the second embodiment has the same configuration as the configuration in which the recessed portion 23a of the end 23 is omitted from the upper tether 21. That is, the upper tether 121 is provided with a recess 22 a only at one end 22 of the both ends 22 and 23.

(Embodiment 3)
The upper tether 221 in the third embodiment has the same configuration as that of the upper tether 21 in which the shapes of the recess 22a of the end 22 and the recess 23a of the end 23 are both changed. That is, the upper tether 221 includes a step-shaped recess 122 a at the end 22 and a step-shaped recess 123 a at the end 23. The upper tether 221 includes a narrow portion 24 and a wide portion 25, but does not include a portion corresponding to the gradually changing portion 26 of the upper tether 21. And the recessed parts 122a and 123a are comprised using the narrow part 24 of the top tether 221. FIG.

(Embodiment 4)
The upper tether 321 in the fourth embodiment has the same configuration as that of the upper tether 221 in which the recessed portion 123a of the end 23 is omitted. That is, the upper tether 321 includes a recess 122 a only at one end 22 of the both ends 22 and 23.

In any of the above-described second to fourth embodiments, as in the case of the first embodiment, the occupant C is provided by the airbag 10 inflated and deployed by providing the recessed portion 22a or the recessed portion 122a at at least one end portion 22. The knees K and K are not easily pushed to the left and right, and the movement of the knees K and K to the outside can be suppressed.
In addition, the same effects as those of the first embodiment are obtained.

  The present invention is not limited to the above-described exemplary embodiments, and various applications and modifications can be considered without departing from the object of the present invention. For example, the following embodiments applying the above-described embodiment can be implemented.

  In the above embodiment, when the airbag 10 is inflated and deployed, the opening end 22b of the recessed portion 22a of the upper tether 21 is disposed on the first imaginary line L1, and the opening end 22c of the recessed portion 22a is the second imaginary line L2. Although the case where it arrange | positions above was illustrated, the opening ends 22b and 22c of the recessed part 22a may be arrange | positioned in the position which remove | deviated from virtual line L1, L2. For example, a configuration is adopted in which the opening ends 22b and 22c of the recessed portion 22a are arranged in a region defined by a virtual line passing outside the one knee K and a virtual line passing outside the other knee K. be able to.

  In the above embodiment, the configuration in which the recessed portion is provided in at least one of the both end portions of the upper tether has been illustrated, but the present configuration can also be applied to the lower tether. When this configuration is applied to both the upper tether and the lower tether, even if the knee position is shifted in the vertical direction of the airbag (vehicle vertical direction) due to the difference in the occupant's physique, the dent of the lower tether It becomes possible to suppress the crotch opening.

  In the above embodiment, the case where two tethers of the upper tether and the lower tether are joined to the inner wall of the knee airbag has been illustrated. However, a form using only the upper tether or a further separate in addition to the upper tether and the lower tether. It is also possible to adopt a form using the tether.

  In the above-described embodiment, the case where a plurality of gas circulation openings are provided in both the upper tether and the lower tether is illustrated, but the number of gas circulation openings may be one in each tether.

  In the above embodiment, the case where the recessed portion is formed using the narrow portion in the width direction of the upper tether has been illustrated, but the recessed portion can be formed without providing the narrow portion in the upper tether. For example, a recess may be provided at one end in the width direction of the upper tether, and a protrusion having the same shape as the recess may be provided on the same axis in the width direction as the recess. In this case, the tether width in the width direction is made uniform in the longitudinal direction by matching the tether width between the concave portion and the convex portion with the tether width of the other portion.

  In the above embodiment, the case where the opening area of the gas circulation opening 21a provided in the central portion of the upper tether is less than the opening area of the gas circulation opening 21b is illustrated, but the opening area of the gas circulation opening 21a is as necessary. Can be set equal to or larger than the opening area of the gas flow opening 21b.

  In the above embodiment, the knee airbag device used for the passenger seated on the driver's seat is illustrated, but the same device as the knee airbag device corresponds to the passenger seat among the interior members of the vehicle. It can also be installed at the position.

  In view of the above-described embodiment and other modified examples, the following modes are conceivable.

As one aspect,
"A knee airbag that is mounted on a vehicle and receives the supply of gas to inflate and deploy to restrain both occupants' knees,
With a tether that regulates the inflation and deployment of the knee airbag,
The tether has a long strip shape extending in the longitudinal direction, both ends in the width direction orthogonal to the longitudinal direction are joined to the bag inner wall, and at least one of the both ends is recessed in the width direction. A knee that includes a recess, extends in the vehicle lateral direction as the longitudinal direction when the knee airbag is inflated and deployed, and is disposed on the vehicle rear side so that the recess faces the knees of the occupant. Airbag. "
It can take the form.
According to this aspect, it is possible to provide a knee airbag that can suppress, with a simple structure, an operation in which both knee portions of an occupant open outward during inflation and deployment.

As another aspect,
“A passenger including a knee airbag device, a collision detection sensor that detects a vehicle collision, and a control unit that outputs a control signal to the knee airbag device when the collision detection sensor detects a vehicle collision. A protection system,
The knee airbag device is
An inflator that operates in response to a control signal from the control unit to generate gas;
A knee airbag that receives the gas supply from the inflator and inflates and restrains both occupant knees;
A tether that regulates inflation and deployment of the knee airbag,
The tether has a long strip shape extending in the longitudinal direction, and is joined to the inner wall of the knee airbag at both ends in the width direction perpendicular to the longitudinal direction, and at least one of the both ends A recessed portion recessed in the width direction, extending in the vehicle lateral direction as the longitudinal direction when the knee airbag is inflated and deployed, and on the vehicle rear side so that the recessed portion faces both knees of the occupant An occupant protection system that is deployed. "
It can take the form.
According to this aspect, it is possible to provide an occupant protection system including a knee airbag device that can suppress an operation of opening both knee portions of the occupant outward when the knee airbag is inflated and deployed with a simple structure.

1 knee airbag device 10 knee airbag (airbag)
11 First chamber 12 Second chamber 13 Third chamber 20 Tether 21, 121, 221, 321 Upper tether 21a, 21b, 21c Gas flow opening 22, 23 End 22a, 23a, 122a, 123a Recess 22b, 22c Open end 22d bottom 24 narrow part 27 lower tether (tether)
27a, 27b, 27c Gas distribution openings 28, 29 End 100 Vehicle L1 First imaginary line L2 Second imaginary line

Claims (7)

A knee airbag device mounted on a vehicle,
A knee airbag that receives gas supply and inflates and deploys to restrain both occupants'knees;
A tether that regulates inflation and deployment of the knee airbag,
The tether has a long strip shape extending in the longitudinal direction, and is joined to the inner wall of the knee airbag at both ends in the width direction perpendicular to the longitudinal direction, and at least one of the both ends A recessed portion recessed in the width direction, extending in the vehicle lateral direction as the longitudinal direction when the knee airbag is inflated and deployed, and on the vehicle rear side so that the recessed portion faces both knees of the occupant Arranged knee airbag device.   The tether is disposed on a first imaginary line passing through the center of one knee of the occupant in the width direction when the knee airbag is inflated and deployed. 2. The knee airbag device according to claim 1, wherein the other opening end is disposed on a second imaginary line passing through the center of the other knee portion of the occupant in the width direction.   3. The knee airbag device according to claim 1, wherein the tether is configured such that the opening width in the longitudinal direction of the recess is gradually narrowed toward the bottom surface. 4.   The knee airbag device according to any one of claims 1 to 3, wherein the tether includes the recessed portion at a symmetrical position in the width direction of both the end portions.   The said tether is provided with the narrow part with a relatively narrow tether width | variety of the said width direction of the said both ends, The said recessed part is comprised using the said narrow part, The any one of Claims 1-4 The knee airbag device according to one item.   The tether includes a plurality of gas circulation openings, and is configured such that an opening area of a gas circulation opening located in the vicinity of the recessed portion of the plurality of gas circulation openings is smaller than an opening area of another gas circulation opening. The knee airbag device according to any one of claims 1 to 5. When the tether is an upper tether, a lower tether that is joined to the inner wall of the knee airbag and has a gas flow opening is provided separately from the upper tether. Placed below the tether,
The knee airbag includes a first chamber formed below the lower tether and first supplied with the gas; a second chamber formed between the lower tether and the upper tether; The knee airbag device according to any one of claims 1 to 6, further comprising a third chamber formed above the tether.

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