Ceiling-mounted airbag device and occupant restraint apparatus

Abstract

To provide a ceiling-mounted airbag device capable of effectively restraining an occupant irrespective of a position, in a front-rear direction, of a vehicle seat; and to provide an occupant restraint apparatus including the same.SOLUTION: A ceiling-mounted airbag device 30 includes: an airbag 32 mounted on an upper side of a ceiling of a cabin and including a first chamber 34 which, when gas is supplied from an inflator 28 upon a head-on collision of a vehicle, thereby ruptures the ceiling and is expanded and deployed in front of an occupant P seated in a vehicle seat 12, and a second chamber 36 which, when the gas is supplied from the first chamber 34, is thereby expanded and deployed toward the occupant P; and a tension member 38 which couples the first chamber 34 to a support part 22 provided on the upper side of the ceiling, which ruptures the ceiling and is deployed with expansion and deployment of the first chamber 34, and which relatively pulls the first chamber 34 rearward and upward when the second chamber 36 restrains the occupant P about to move forward due to inertia force. An occupant restraint apparatus 10 includes the ceiling-mounted airbag device 30.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a ceiling-mounted airbag device and an occupant restraint device. [Background technology]

[0002] An occupant protection device having an airbag formed with a single chamber that deploys downward from the ceiling of the vehicle in the event of a frontal collision and is positioned in front of the occupant, and a tether that connects the lower end of the airbag to the ceiling behind the airbag storage section, has been known for some time (see, for example, Patent Document 1).

[0003] Also, a passenger protection device has been known that includes an airbag formed from a single chamber that is stored in the roof side of the vehicle and deploys downward to receive the head of the passenger in the event of a frontal collision of the vehicle, and a connecting member that connects both sides of the lower end of the airbag to the roof behind the airbag storage section (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-161965 A [Patent Document 2] Patent Publication No. 2021-054100 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the relative positional relationship in the front-rear direction between the airbag, which is deployed downward from the ceiling and positioned in front of the occupant, and the occupant (upper body including the head), changes depending on the front-rear position of the vehicle seat. Therefore, depending on the front-rear position of the vehicle seat, the airbag may not be able to provide sufficient occupant restraint performance (may not effectively restrain the occupant).

[0006] SUMMARY OF THE PRESENT DISCLOSURE An object of the present invention is to provide a ceiling-mounted airbag device capable of effectively restraining an occupant regardless of the fore-aft position of a vehicle seat, and an occupant restraint device including the same. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, a ceiling-mounted airbag device of a first aspect of the present invention is an airbag that is mounted on the vehicle upper side of the ceiling of a vehicle compartment, and that, in the event of a frontal collision of the vehicle, has a first chamber that, when gas is supplied from an inflator, tears open the ceiling and inflates and deploys toward the vehicle front of an occupant sitting in a vehicle seat, and a second chamber that, when gas is supplied from the first chamber, inflates and deploys toward the occupant, and a pulling member that connects the first chamber to a support portion provided on the vehicle upper side of the ceiling, and that tears open the ceiling and deploys as the first chamber inflates and deploys, and when the second chamber restrains the occupant who is attempting to move toward the vehicle front due to inertial force, pulls the first chamber relatively toward the rear side of the vehicle and toward the vehicle upper side.

[0008] According to the first aspect of the invention, in the event of a frontal collision of the vehicle, the first chamber of the airbag splits the ceiling of the vehicle compartment and inflates and deploys toward the vehicle front of the occupant sitting in the vehicle seat as gas is supplied from the inflator, and further, the second chamber of the airbag splits and deploys from the first chamber toward the occupant as gas is supplied from the first chamber. As the first chamber inflates and deploys, the tension member connecting the first chamber and the support part provided on the upper side of the ceiling splits the ceiling and deploys, and when the occupant who is moving toward the vehicle front due to inertial force is restrained by the second chamber, the tension member pulls the first chamber relatively toward the rear and upper side of the vehicle.

[0009] Therefore, the load from the occupant who moves to the front side of the vehicle due to the inertial force is effectively received by the second chamber, which is pulled relatively to the rear side of the vehicle and to the upper side of the vehicle via the first chamber by the tension member. In other words, even if the second chamber is pressed to the front side of the vehicle by the occupant when restraining the occupant, a reaction force is obtained in the first chamber pulled by the tension member, so that the occupant is effectively restrained by the compressive deformation of the second chamber. Therefore, compared with a ceiling-mounted airbag formed with a single chamber, it is easier to absorb changes in the front-to-rear position of the vehicle seat, and the area in which occupant restraint performance (occupant protection performance) can be obtained is expanded. Thus, according to the present invention, the occupant is effectively restrained regardless of the front-to-rear position of the vehicle seat. Note that "at the time of a frontal collision" as used herein also includes a time when the inevitability of a frontal collision is predicted (foreseen).

[0010] In addition, a ceiling-mounted airbag device of a second aspect of the present invention is a ceiling-mounted airbag device of the first aspect, wherein the tensile member is composed of a surface tether that covers at least the upper half of the inflated and deployed second chamber when viewed from the side.

[0011] According to the second aspect of the invention, the tension member is configured with a surface tether that covers at least the upper half of the inflated and deployed second chamber in a side view, which prevents, for example, the neck of the occupant from getting caught in the belt tether, compared to when the tension member is configured with a pair of left and right belt tethers that cover only the lower end of the inflated and deployed second chamber in a side view.

[0012] A ceiling-mounted airbag device of a third aspect of the present invention is a ceiling-mounted airbag device of the first or second aspect, wherein the second chamber is provided below the vehicle vertical center of the first chamber and is configured to be able to restrain at least the head and chest of the occupant.

[0013] According to the third aspect of the invention, the second chamber is provided below the vehicle vertical center of the first chamber, and is configured to be able to restrain at least the head and chest of the occupant. Therefore, compared to a ceiling-mounted airbag formed of a single chamber that covers at least from the ceiling to the chest of the occupant, an increase in the volume of the airbag (first and second chambers) is suppressed. In other words, an increase in the output of the inflator is suppressed, and manufacturing costs are reduced accordingly. In addition, since at least the head and chest of the occupant are restrained by the compressive deformation of the second chamber, there is no risk of the occupant's neck bending backward significantly.

[0014] A ceiling-mounted airbag device of a fourth aspect of the present invention is a ceiling-mounted airbag device of any one of the first to third aspects, wherein a restricting tether is provided inside the second chamber for restricting the length of the second chamber along the fore-and-aft direction of the vehicle, and the restricting tether is configured such that the restriction is released when the vehicle seat is positioned further rearward of the vehicle than a predetermined position.

[0015] According to the invention of the fourth aspect, the restriction tether provided inside the second chamber for restricting the length (thickness) of the second chamber along the vehicle front-rear direction is configured to release the restriction when the vehicle seat is positioned at a position at least on the vehicle rear side. Therefore, when the vehicle seat is positioned at a position at the vehicle front side of the predetermined position, the occupant is restrained by the second chamber whose thickness is restricted by the restriction tether. When the vehicle seat is positioned at a position at least on the vehicle rear side, the occupant is restrained by the second chamber whose restriction is released and which is expanded toward the vehicle rear side. In other words, even when the vehicle seat is positioned at a position at least on the vehicle rear side, the occupant is restrained more effectively and appropriately than a ceiling-mounted airbag formed of a single chamber.

[0016] A ceiling-mounted airbag device according to a fifth aspect of the present invention is the ceiling-mounted airbag device according to the fourth aspect, wherein the restriction tether is configured to be released from the restriction by being cut.

[0017] According to the fifth aspect of the invention, the restriction tether is configured to be released by being cut, which allows the structure of the restriction tether to be simpler than a configuration in which the restriction is released by, for example, releasing one end of the restriction tether.

[0018] A ceiling-mounted airbag device of a sixth aspect of the present invention is a ceiling-mounted airbag device of the fifth aspect, wherein the inflator is configured to be able to change its output based on the detection results of the front-to-rear position of the vehicle seat, and the regulating tether is configured to be cut by an increase in the output of the inflator.

[0019] According to the sixth aspect of the invention, the restriction tether is cut by increasing the output of the inflator, the output of which is variable, based on the detection result of the front-rear position of the vehicle seat. Therefore, the configuration is simpler than when a separate mechanism for cutting the restriction tether is provided, for example.

[0020] In addition, in a passenger restraint device according to a seventh aspect of the present invention, a ceiling-mounted airbag device according to any one of the first to sixth aspects is provided for each vehicle seat.

[0021] According to the seventh aspect of the invention, a ceiling-mounted airbag device of any one of the first to sixth aspects is provided for each vehicle seat, so that occupants are effectively and appropriately restrained depending on the fore-and-aft position of each vehicle seat.

[0022] Moreover, in an occupant restraint device according to an eighth aspect of the present invention, the ceiling-mounted airbag device according to any one of the first to sixth aspects is provided for each of adjacent vehicle seats on the left and right.

[0023] According to the eighth aspect of the invention, a ceiling-mounted airbag device of any one of the first to sixth aspects is provided for each adjacent vehicle seat on the left and right, thereby reducing the number of parts and reducing manufacturing costs.

[0024] Furthermore, a ninth aspect of the present invention is an occupant restraint device according to the eighth aspect, wherein a single first chamber is provided for vehicle seats adjacent to each other on the left and right, and a second chamber is provided for each of the vehicle seats adjacent to each other on the left and right.

[0025] According to the ninth aspect of the invention, a single first chamber is provided for the left and right adjacent vehicle seats, and a second chamber is provided for each of the left and right adjacent vehicle seats. This reduces the number of parts (reducing manufacturing costs), and effectively and appropriately restrains the occupant according to the front-rear position of each vehicle seat. Effect of the Invention

[0026] As described above, according to the present invention, it is possible to effectively restrain an occupant regardless of the fore-aft position of the vehicle seat. [Brief description of the drawings]

[0027] [Figure 1] 1 is a schematic side view showing a state in which a ceiling-mounted airbag device according to a first embodiment is mounted on the upper side of a ceiling of a vehicle compartment. [Diagram 2] 1 is a schematic side view showing an initial state of inflation and deployment of an airbag of a ceiling-mounted airbag device according to a first embodiment. FIG. [Diagram 3] FIG. 2 is a schematic side view showing a later stage of inflation and deployment of the airbag of the ceiling-mounted airbag device according to the first embodiment. [Figure 4] 1A to 1C are schematic plan views showing the process of inflation and deployment of an airbag in a ceiling-mounted airbag device according to the first embodiment. [Diagram 5] 13 is a schematic side view showing an initial state of inflation and deployment of an airbag of a ceiling-mounted airbag device according to a second embodiment. FIG. [Figure 6] 13 is a schematic side view showing a later stage of inflation and deployment of the airbag of the ceiling-mounted airbag device according to the second embodiment when the vehicle seat is positioned forward of a predetermined position. FIG. [Figure 7] 13 is a schematic side view showing a later stage of inflation and deployment of the airbag of the ceiling-mounted airbag device according to the second embodiment when the vehicle seat is positioned rearward at a predetermined position or further. FIG. [Figure 8] 13(A) to 13(C) are schematic plan views showing the inflation and deployment process of airbags in ceiling-mounted airbag devices according to a third embodiment provided for left and right adjacent vehicle seats. [Figure 9] 11A to 11C are schematic plan views showing the inflation and deployment process of an airbag of a ceiling-mounted airbag device according to a third embodiment, which is provided for each adjacent vehicle seat on the left and right, when a second chamber is provided for each vehicle seat. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. For convenience of explanation, the arrow UP shown in each drawing indicates the upward direction of the vehicle and the vehicle seat, the arrow FR indicates the forward direction of the vehicle and the vehicle seat, and the arrow RH indicates the rightward direction of the vehicle and the vehicle seat. Therefore, in the following description, when the directions of up / down, front / rear, and left / right are described without special mention, they refer to up / down, front / rear, and left / right of the vehicle and the vehicle seat. In addition, the left / right direction is synonymous with the vehicle width direction and the seat width direction.

[0029] First Embodiment First, a first embodiment will be described. As shown in Fig. 1 to Fig. 4, an occupant restraint device 10 includes a vehicle seat 12 and a ceiling-mounted airbag device 30 (hereinafter, sometimes simply referred to as "airbag device 30") provided for each vehicle seat 12.

[0030] The vehicle seat 12 is a front seat or a rear seat of a vehicle such as an autonomous vehicle that has a wide front-rear seat front side. The vehicle seat 12 has a seat cushion 14 on which an occupant sits (supporting the occupant's buttocks and thighs), a seat back 16 that is provided on the rear side of the seat cushion 14 so as to be rotatable about the seat width direction as an axial direction and supports the occupant's back, and a headrest 18 that is provided on the upper end of the seat back 16 so as to be movable up and down and supports the occupant's head.

[0031] In each figure, a crash test dummy (human dummy) is shown seated on the seat cushion 14 of the vehicle seat 12 as a model of the occupant (seater) to be protected. The dummy is, for example, a frontal crash test dummy (Hybrid III) AM50 (50th percentile of American adult males). The dummy is seated in a standard seating position defined by the crash test method, and the vehicle seat 12 is located at a reference setting position corresponding to the seating position. Hereinafter, the dummy will be referred to as "occupant P."

[0032] An occupant P seated on the seat cushion 14 of the vehicle seat 12 is restrained to the vehicle seat 12 by a seat belt provided in a seat belt device (not shown). The seat belt device is a three-point seat belt device.

[0033] An airbag device 30 is mounted above the ceiling (roof head lining) 20 of the vehicle compartment on the front side of the vehicle seat 12. The airbag device 30 includes an airbag 32, an inflator 28, and a module case 26. The airbag 32 is normally stored in a folded state together with the inflator 28 in the module case 26. The module case 26 is formed in a hollow, generally rectangular parallelepiped shape, and is installed above the ceiling 20 of the vehicle compartment. The module case 26 may be installed below a roof panel (not shown) (between the roof head lining and the roof panel).

[0034] The vehicle is equipped with a control device (ECU) that controls the operation of the inflator 28. The control device is electrically connected to the inflator 28 and a collision sensor (including a camera, etc.) not shown, and is configured to be able to detect a frontal collision of the vehicle or predict (foresee) the inevitability of a frontal collision. The control device is configured to activate the inflator 28 when it detects or predicts a frontal collision of the vehicle (hereinafter referred to as "at the time of a frontal collision") based on information from the collision sensor.

[0035] The inflator 28 is, for example, a combustion-type or cold gas-type, substantially cylindrical inflator, and is disposed with its axis aligned along the front-rear direction. The inflator 28 is activated by a control device at the time of a frontal collision of the vehicle to generate gas. Note that the type of frontal collision of the vehicle in which the control device activates the inflator 28 includes, in addition to a full-wrap frontal collision, an offset frontal collision such as an oblique collision or a minute-wrap collision.

[0036] The airbag 32 is configured to split the ceiling 20 and inflate (deploy and inflate) forward of the occupant P seated in the vehicle seat 12 by inflation pressure caused by gas supplied from the inflator 28. The ceiling 20 is formed with a tear line (not shown) as a breaking portion for splitting, and the airbag 32 is configured to rupture and deploy by breaking the tear line. The portion that breaks from the tear line and turns up forms an airbag door (not shown).

[0037] The airbag 32 has a first chamber 34 and a second chamber 36. When gas is first supplied from the inflator 28 to the first chamber 34, the first chamber 34 ruptures a tear line formed in the ceiling 20 and inflates downward, and is positioned forward at a distance of a predetermined length or more from the occupant P seated in the vehicle seat 12. The first chamber 34 after inflation and deployment is configured to be shorter in length (thinner) in the front-rear direction than the second chamber 36 after inflation and deployment.

[0038] The second chamber 36 is provided below the vertical center of the rear wall 34B of the first chamber 34 via a communication hole 35, and gas is supplied from the first chamber 34 through the communication hole 35. In other words, the second chamber 36 is configured to inflate and deploy toward the occupant P (rearward) with a predetermined timing delay relative to the first chamber 34. After inflating and deploying, the second chamber 36 is arranged to be located at least in front of the head and chest of the occupant P.

[0039] The communication hole 35 is provided at approximately the center in the vertical direction and the horizontal direction of the second chamber 36. After being inflated and deployed, the second chamber 36 is formed to have a size (height, width, thickness) capable of restraining at least the head and chest of the occupant P (not only the head but also the chest of the occupant P) that tends to move forward due to inertial force in the event of a frontal collision of the vehicle, and is compressively deformable by being pressed against at least the head and chest of the occupant P (see FIG. 3).

[0040] The first chamber 34 and the second chamber 36 are each formed into a bag shape by overlapping two pieces of base fabric and sewing their peripheral parts. The base fabric is made of, for example, a polyamide or polyester fabric material. The front wall 36F of the second chamber 36 is attached to the rear wall 34B of the first chamber 34 by sewing the periphery of the communication hole 35, which is formed in a circular shape, to each other.

[0041] In addition, on the upper side of the ceiling 20, a surface tether 38 is provided as a tensile member that ruptures a tear line (not shown) formed on the ceiling 20 and deploys downward as the first chamber 34 expands and deploys, connecting the first chamber 34 after expansion and deployment to a pair of support portions 22 provided on the left and right sides above the ceiling 20, at a position rearward of the module case 26 by a predetermined length or more.

[0042] The surface tether 38 is configured to relatively pull the first chamber 34 obliquely upward and rearward (rearward and upward) when at least the head and chest of the occupant P, who is attempting to move forward due to inertial force, are restrained by the second chamber 36. In other words, the first chamber 34, pulled by the surface tether 38, causes the second chamber 36 to receive a reaction force from the front side.

[0043] The deployed surface tether 38 is formed to be large enough to cover at least the left and right sides of the head and neck of the occupant P in a side view seen in the vehicle width direction when at least the head and chest of the occupant P are restrained by the inflated and deployed second chamber 36. In other words, the surface tether 38 is formed to be large enough to cover at least the upper half of the inflated and deployed second chamber 36 in a side view, and its upper edge portion 38U is positioned above the upper end surface 36U of the inflated and deployed second chamber 36 (see FIG. 3).

[0044] In addition, the surface tether 38 is formed to a size that covers almost the entire front wall 34F of the first chamber 34, and the periphery of the area that overlaps to cover the front wall 34F of the first chamber 34 is sewn to the first chamber 34, thereby attaching it to the first chamber 34 (airbag 32).

[0045] In order to facilitate efficient pulling of the first chamber 34 diagonally upward and rearward, the surface tether 38 is formed in a generally right-angled triangle shape with a right angle at its upper front end in side view. In other words, the surface tether 38 is made of a single piece of cloth material, such as polyamide or polyester, and is formed in a generally obtuse-angled isosceles triangle shape in front view.

[0046] Next, the operation of the ceiling-mounted airbag device 30 and the occupant restraint device 10 according to the first embodiment configured as above will be described.

[0047] When the vehicle experiences a frontal collision, the inflator 28 is activated by the control of the control device, and gas is ejected from the inflator 28. The gas ejected from the inflator 28 is supplied to the first chamber 34 of the airbag 32. Then, the tear line formed on the ceiling 20 of the passenger compartment is ruptured by the inflation pressure of the first chamber 34, and the first chamber 34 of the airbag 32 is inflated and deployed downward.

[0048] That is, the first chamber 34 inflates and deploys forward at a distance of at least a predetermined length from the occupant P seated in the vehicle seat 12. Then, as gas is supplied from the first chamber 34 through the communication hole 35, the second chamber 36 inflates and deploys toward the occupant P (rearward) with a predetermined delay from the first chamber 34.

[0049] As the first chamber 34 inflates and deploys, the surface tether 38 that connects the inflated and deployed first chamber 34 to the pair of left and right support parts 22 provided on the upper side of the ceiling 20 ruptures the tear line formed on the ceiling 20 and deploys. When the second chamber 36 restrains at least the head and chest of the occupant P who is attempting to move forward due to inertial force, the surface tether 38 relatively pulls the first chamber 34 diagonally upward and rearward (rearward and upward). In other words, the surface tether 38, together with the first chamber 34, forms a reaction surface against the second chamber 36.

[0050] Therefore, the load from the occupant P who moves forward due to inertial force can be effectively received by the second chamber 36 which is pulled relatively diagonally upward and rearward via the first chamber 34 by the surface tether 38. In other words, even if the second chamber 36 is pressed forward by the occupant P when the occupant is restrained, a reaction force is obtained from the first chamber 34 which is pulled by the surface tether 38, so that the second chamber 36 is compressed and deformed, and at least the head and chest of the occupant P can be restrained.

[0051] Therefore, compared to a ceiling-mounted airbag (not shown) formed with a single chamber, it is easier to absorb changes in the fore-aft position of the vehicle seat 12, and the area in which occupant restraint performance (occupant protection performance) can be obtained can be expanded. Thus, according to the first embodiment, regardless of the fore-aft position of the vehicle seat 12, at least the head and chest of the occupant P who moves forward due to inertia caused by the impact of a frontal collision of the vehicle can be effectively and appropriately restrained.

[0052] In addition, the tension member that pulls the first chamber 34 diagonally rearward and upward is composed of a surface tether 38 that covers at least the upper half of the inflated and deployed second chamber 36 in a side view. Therefore, compared to a case in which the tension member is composed of a pair of left and right belt tethers (not shown) that connect the lower end of the inflated and deployed second chamber 36 to the support part 22, it is possible to prevent the occurrence of a problem such as injury to the neck of the occupant P being caught in the belt tether.

[0053] Also, the second chamber 36 is provided below the vertical center of the first chamber 34 and is configured to be able to restrain at least the head and chest of the occupant P. Therefore, an increase in the volume of the airbag 32 (the first chamber 34 and the second chamber 36) can be suppressed compared to a ceiling-mounted airbag (not shown) formed of a single chamber that covers at least from the ceiling to the chest of the occupant P. In other words, an increase in the output of the inflator 28 can be suppressed, and the manufacturing cost can be reduced accordingly.

[0054] In addition, the second chamber 36 comes into contact with a wide area of ​​the upper body (at least the head and chest) of the occupant P, and the second chamber 36 restrains not only the head but also the chest of the occupant P by compressive deformation of the second chamber 36, so that it is possible to improve the energy absorption performance of the second chamber 36 and reduce the load applied to the occupant P from the second chamber 36. Therefore, there is no risk of the occupant P bending backwards in the neck, and even if the neck does bend backwards, there is no risk of the bending backwards in the neck becoming large.

[0055] In addition, since the second chamber 36 inflates and deploys after the first chamber 34, the occurrence of improper deployment of the airbag 32 can be suppressed or prevented compared to a case in which the second chamber 36 inflates and deploys by rupturing the tear line of the ceiling 20 at the same time as the first chamber 34. In addition, since the airbag device 30 is provided for each vehicle seat 12, the occupant P can be effectively and appropriately restrained according to the fore-aft position of each vehicle seat 12.

[0056] <Second embodiment> Next, a second embodiment will be described. Note that the same reference numerals are used to designate the same parts as those in the first embodiment, and detailed descriptions thereof will be omitted as appropriate.

[0057] 5 to 7, the second embodiment differs from the first embodiment only in that a single regulating tether 40 is provided inside the second chamber 36 to regulate the length (thickness) of the second chamber 36 in the front-rear direction. The regulating tether 40 is formed in a band shape having a predetermined thickness and width (length in the left-right direction), and its front end 40F is attached by sewing to the inner surface of the front wall 36F of the second chamber 36 at approximately the center in the up-down direction and approximately the center in the left-right direction, and its rear end 40B is attached by sewing to the inner surface of the rear wall 36B of the second chamber 36 at approximately the center in the up-down direction and approximately the center in the left-right direction.

[0058] The illustrated communication hole 35 is provided below the regulating tether 40 in side view, and the gas supplied from the communication hole 35 to the second chamber 36 flows upward through gaps on both the left and right sides of the regulating tether 40, but is not limited to this. The communication hole 35 may be provided above the regulating tether 40, and the gas supplied from the communication hole 35 to the second chamber 36 may flow downward through gaps on both the left and right sides of the regulating tether 40.

[0059] Moreover, the restriction tether 40 is configured to be released when the vehicle seat 12 is positioned rearward beyond a predetermined position. Specifically, the inflator 28 is configured to be able to change its output based on the detection result of the front-rear position of the vehicle seat 12, and the restriction by the restriction tether 40 is released by increasing the output of the inflator 28 and breaking the restriction tether 40.

[0060] The front-rear position of the vehicle seat 12 is detected by a seat slide sensor (not shown) provided in the vehicle, and this seat slide sensor is also electrically connected to a control device that controls the operation of the inflator 28. The inflator 28 is a dual inflator, and is configured so that the output can be controlled in two stages.

[0061] Although not shown, the regulating tether 40 is configured such that the width of a predetermined portion is smaller than the width of other portions, or the predetermined portion has a perforation or other cut along the width direction, so that the predetermined portion is cut when a predetermined tension is exceeded. This allows the regulating tether 40 to be automatically cut from the predetermined portion when the tension of the regulating tether 40 acting due to the expansion of the second chamber 36 exceeds a predetermined value.

[0062] Next, the operation of the ceiling-mounted airbag device 30 and the occupant restraint device 10 according to the second embodiment configured as described above will be described. Note that the explanation of the operation common to the first embodiment will be omitted as appropriate.

[0063] As described above, the thickness (length along the front-rear direction) of the second chamber 36 is restricted by the restricting tether 40 provided inside the second chamber 36. Therefore, when the vehicle seat 12 is positioned forward of a predetermined position, at least the head and chest of the occupant P can be restrained by the second chamber 36 whose thickness is restricted by the restricting tether 40. In other words, the occupant P who has moved forward due to inertia caused by the impact of a frontal collision of the vehicle can be effectively and appropriately restrained.

[0064] On the other hand, when the vehicle seat 12 is positioned rearward of the vehicle by a predetermined position or more, the restricting tether 40 is cut by the increased output of the inflator 28, and the restriction is released. Therefore, when the vehicle seat 12 is positioned rearward of the predetermined position or more, the restriction is released and at least the head and chest of the occupant P can be restrained by the second chamber 36 expanded rearward. In other words, even when the vehicle seat 12 is positioned rearward of the predetermined position or more, the occupant P who has moved forward due to inertia caused by the impact of a frontal collision of the vehicle can be restrained more effectively and appropriately than with a ceiling-mounted airbag formed with a single chamber.

[0065] Furthermore, since the regulating tether 40 is configured so that the restriction is released when it is cut, the structure of the regulating tether 40 is simpler than a configuration in which the restriction is released, for example, by detaching one end (the front end 40F or the rear end 40B) of the regulating tether 40 from the front wall 36F of the second chamber 36 by a mechanical structure.

[0066] In addition, the restricting tether 40 is cut by increasing the output of the inflator 28, the output of which is variable based on the detection results of the front-rear position of the vehicle seat 12. Therefore, the configuration is simpler than, for example, a case in which a separate mechanism for cutting the restricting tether 40 is provided.

[0067] Note that the inflator 28 may not be a dual inflator, but may be provided with two inflators 28 to increase output. That is, when the vehicle seat 12 is located forward of a predetermined position, only one inflator 28 may be activated, and when the vehicle seat 12 is located rearward of the predetermined position or further, the second inflator 28 may be activated following the activation of the first inflator 28.

[0068] <Third embodiment> Next, a third embodiment will be described. Note that the same reference numerals are used for the same parts as those in the first and second embodiments, and detailed descriptions (including common functions) will be omitted as appropriate.

[0069] 8, the third embodiment differs from the first and second embodiments only in that an airbag device 30 is provided for each of the vehicle seats 12 adjacent to each other on the left and right. Specifically, a single first chamber 34 and a single second chamber 36 of the airbag 32 are provided for each of the vehicle seats 12 adjacent to each other on the left and right.

[0070] With this configuration, an airbag device 30 is provided for each vehicle seat 12 adjacent to the left and right, which allows for a reduction in the number of parts and manufacturing costs compared to a case in which an airbag device 30 is provided for each vehicle seat 12.

[0071] 9, a single first chamber 34 may be provided for the left and right adjacent vehicle seats 12, and a second chamber 36 may be provided for each of the left and right adjacent vehicle seats 12. That is, the second chamber 36 may be composed of a right second chamber 36R for the right vehicle seat 12R and a left second chamber 36L for the left vehicle seat 12L.

[0072] With this configuration, an airbag device 30 is provided for each adjacent vehicle seat 12 on the left and right, which reduces the number of parts (reducing manufacturing costs) and enables the occupant P to be effectively and appropriately restrained depending on the fore-and-aft position of each adjacent vehicle seat 12 on the left and right.

[0073] The ceiling-mounted airbag device 30 and the occupant restraint device 10 according to this embodiment have been described above with reference to the drawings. However, the ceiling-mounted airbag device 30 and the occupant restraint device 10 according to this embodiment are not limited to those shown in the drawings, and can be appropriately modified in design within the scope that does not deviate from the gist of the present invention.

[0074] For example, the tension member need only be such that the neck of the occupant P does not get caught on it, and is not limited to the surface tether 38. In the second embodiment, the communication hole 35 may be provided at approximately the center in the vertical direction and the center in the horizontal direction of the second chamber 36, and the restriction tethers 40 may be narrower than those described above and provided in a pair on the left and right sides of the communication hole 35.

[0075] In addition, the restriction tether 40 is not limited to a configuration in which the restriction is released by being cut, and may be configured to release the restriction by releasing one end (the front end 40F or the rear end 40B) of the restriction tether 40, although this would result in a complex structure. In addition, the restriction tether 40 is not limited to a configuration in which the restriction is released by an increase in the output of the inflator 28, and may be configured to be cut by other methods. [Explanation of symbols]

[0076] 10 Occupant restraint system 12 Vehicle seats 20 Ceiling 22 Support part 28 Inflator 30 Ceiling-mounted airbag device 32 Airbag 34 First Chamber 36 Second Chamber 38 Surface tether (tensile member) 40 Regulatory Tether P Crew

Claims

1. an airbag having: a first chamber mounted on the upper side of a ceiling of a vehicle compartment, and inflated and deployed in front of a vehicle occupant seated in a vehicle seat by being supplied with gas from an inflator in the event of a frontal collision of the vehicle; and a second chamber inflated and deployed toward the occupant by being supplied with the gas from the first chamber; a tension member that connects the first chamber and a support portion provided on the upper side of the ceiling of the vehicle, and that tears and deploys the ceiling as the first chamber is inflated and deployed, and that pulls the first chamber relatively toward the rear side of the vehicle and toward the upper side of the vehicle when the occupant who is moving toward the front side of the vehicle due to inertial force is restrained by the second chamber; A ceiling-mounted airbag device.

2. 2. The ceiling-mounted airbag device according to claim 1, wherein the tension member is configured as a surface tether that covers at least an upper half of the inflated and deployed second chamber in a side view.

3. 2. The ceiling-mounted airbag device according to claim 1, wherein the second chamber is disposed below the center of the first chamber in the vertical direction of the vehicle and is configured to restrain at least the head and chest of the occupant.

4. A restricting tether is provided inside the second chamber to restrict the length of the second chamber along the vehicle front-rear direction, 2. The ceiling-mounted airbag device according to claim 1, wherein the restraining tether is configured such that the restraint is released when the vehicle seat is positioned rearward of the vehicle by a predetermined position or more.

5. 5. The ceiling-mounted airbag device according to claim 4, wherein the restriction tether is configured to be released from the restriction by being cut.

6. The inflator is configured to change its output based on a detection result of a front-rear position of the vehicle seat, 6. The ceiling-mounted airbag device according to claim 5, wherein the restriction tether is configured to be cut by an increase in output of the inflator.

7. An occupant restraint device, comprising: a ceiling-mounted airbag device according to any one of claims 1 to 6, which is provided for each vehicle seat.

8. An occupant restraint device, comprising: a ceiling-mounted airbag device according to any one of claims 1 to 6, which is provided for each of adjacent vehicle seats on the left and right.

9. The first chamber is provided singly for each of the vehicle seats adjacent to each other on the left and right sides, 9. The passenger restraint device according to claim 8, wherein the second chamber is provided for each of adjacent vehicle seats on the left and right.

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