JP7629328B2 - Airbag device - Google Patents

Description

The present invention relates to an airbag device having an airbag that deploys from the front of a vehicle such as an automobile to the outside of the vehicle.

2. Description of the Related Art In vehicles such as automobiles, it has been proposed to use airbags that deploy to the outside of the vehicle to reduce injury to pedestrians and the like in the event of a collision.
As an example of technology relating to such external airbag devices, Patent Document 1 describes a cylindrical airbag that is deployed in the fore-and-aft direction of the vehicle while being aligned with the outer surface of the vehicle in order to absorb impact even in the event of a collision with a tall pedestrian, and that divides the bag longitudinally into multiple chambers by multiple tethers and connects the chambers together.
Patent document 2 describes that the inflatable body of an airbag device for protecting occupants is constructed by stacking multiple inflatable sections, and that the internal pressure of the inflatable section closest to the occupant is set to be higher than the internal pressure of the other inflatable sections.
Patent Document 3 describes an airbag device that inflates and deploys an airbag on the front side of a vehicle, in which the inside of the airbag is divided by a partition with holes and a vent hole is provided in the area away from the inflator.

JP 2006-159970 A JP 2006-160122 A JP 2007-137252 A

2. Description of the Related Art There is a demand for reducing damage to pedestrians and bicyclists (hereinafter referred to as "pedestrians, etc.") in the event of a collision between a vehicle and such pedestrians and bicyclists.
An object of the present invention is to provide an airbag device which reduces damage to pedestrians and the like.

In order to solve the above-mentioned problems, the airbag device of the present invention is an airbag device comprising an airbag that deploys forward from the front of the vehicle body, a collision determination unit that establishes a pre-crash determination when the possibility of a collision is equal to or greater than a predetermined threshold, and an airbag deployment control unit that gives a command to an inflator in response to the pre-crash determination to introduce deployment gas into the airbag and deploy the airbag, wherein the airbag is configured with a number of air chambers arranged in the fore-and-aft direction of the vehicle, the internal pressures of the air chambers located at the front and rear ends of the airbag being higher than the internal pressure of an air chamber located in the middle.
With this, when an object such as a pedestrian collides with the airbag, the low-pressure air chamber located in the middle part is first contracted, and then the air chambers with relatively high internal pressure are successively contracted, thereby enabling effective energy absorption.
In addition, by making the air chambers located at the front and rear ends higher pressure than the air chamber located in the middle section, the shape stability of these air chambers is improved, and deformation of the airbag that could cause unstable contact with the object of collision or energy absorption can be suppressed.
In addition, it is possible to gradually increase the reaction force applied from the airbag to the collision object from an initial relatively low state, thereby preventing the collision object from receiving a high reaction force in the early stages of the collision.
As a result, the collision energy is effectively absorbed, and the collision object is pushed forward toward the vehicle body, accelerating it, reducing the relative speed between the collision object and the vehicle body, thereby minimizing damage to the collision object.

In the present invention, the multiple air chambers of the airbag can be supplied with the deployment gas from a common inflator, and the internal pressures can be made different by varying the pressure loss in an introduction flow path of the deployment gas from the inflator.
According to this, the pressure in each air chamber can be made different by a simple configuration, and the above-mentioned effect can be obtained.

In the present invention, the expansion gas may be introduced into some of the air chambers arranged in the middle portion of the plurality of air chambers of the airbag via the insides of the other air chambers.
This makes it possible to reduce the internal pressure of some of the air chambers relative to the other air chambers with a simple structure by utilizing the pressure loss that occurs when the deployment gas passes through the other air chambers.

In the present invention, the multiple air chambers of the airbag are configured to allow the deployment gas to communicate with each other, and only some of the air chambers located in the middle portion can be provided with vent holes for releasing the deployment gas to the outside.
This allows excess deployment gas to be released to the outside through the vent hole, preventing the internal pressure of the air chamber, which should be kept low, from becoming high due to compressive deformation of the air chamber or the inflow of gas from other air chambers, which would result in the impairment of the above-mentioned functions.

In the present invention, the inflator can be configured to additionally supply deployment gas so that, after the airbag is deployed, the internal pressure of at least one of the air chambers located at the front end and the rear end of the airbag becomes equal to or higher than a predetermined level.
With this, even if some of the deployment gas leaks out from vent holes or the like after a collision, it is possible to maintain the internal pressure of at least one of the air chambers located at the front and rear ends at a predetermined level or higher, thereby ensuring the shape stability of the airbag before and after the collision.

As described above, the present invention provides an airbag device that reduces damage to pedestrians and other people.

1 is a diagram showing a schematic configuration of an embodiment of an airbag device to which the present invention is applied; 1 is a schematic cross-sectional view showing a structure of an airbag in an airbag device according to an embodiment of the present invention; 1 is a block diagram showing a schematic configuration of a system for controlling an airbag device according to an embodiment of the present invention;

Hereinafter, an embodiment of an airbag device to which the present invention is applied will be described.
The airbag device of the embodiment is provided in the front of a vehicle such as a passenger car, and is intended to provide protection (reduction of damage) in the event of a collision with a human body such as a pedestrian or a cyclist.
FIG. 1 is a diagram showing a schematic configuration of an airbag device according to an embodiment.
FIG. 1 shows a vehicle having an airbag device according to an embodiment as viewed from above.
The vehicle 1 has, for example, a so-called two-box vehicle shape having an engine compartment 20 that protrudes forward from a passenger compartment 10 .

The vehicle interior 10 is a portion having a space in which passengers and the like are accommodated.
The engine compartment 20 is a portion having a space in which power train components such as an engine, a transmission, and in the case of an electric vehicle, a motor generator and its control devices are housed.
The engine compartment 20 is provided with a front side frame 21, a bumper beam 22, a front bumper 23, etc.

The front side frame 21 is a structural member that protrudes forward from a toe board (not shown), which is a partition wall provided at the front end of the passenger compartment 10 .
The front side frame 21 functions as a base to which, for example, a power train, a cross member to which a front suspension is attached, and a strut housing that accommodates a strut of a MacPherson strut type front suspension are attached.
The front side frame 21 is formed by assembling and welding members formed by press-molding steel plates, for example, so that its cross-sectional shape when viewed from the vehicle longitudinal direction is a rectangular closed cross-section.

The bumper beam 22 is a structural member provided at the front of the vehicle body and extending in the vehicle width direction.
The bumper beam 22 is formed into a beam shape with a closed cross section by, for example, assembling and welding members formed by press-molding steel plates, or by using an extruded aluminum alloy material.
The bumper beam 22 has a middle portion connected to the front end portions of the left and right front side frames 21 .
Both ends of the bumper beam 22 in the vehicle width direction protrude outward in the vehicle width direction relative to the front side frames 21 .
The bumper beam 22 is a load transmitting member that transmits the load received by an airbag 30 (described later) from a human body or object in a collision to the rear side of the vehicle body via the front side frames 21 .

The front bumper 23 is an exterior member provided at the front end of the vehicle body, and is configured by attaching a bumper face constituting a skin portion, which is formed from, for example, a PP-based resin, to the vehicle body by brackets or the like (not shown).
The front portion of the front bumper 23 is curved so that the front side of the vehicle 1 is convex when viewed from above.
When the vehicle 1 is viewed from above, the bumper beam 22 is formed in an arc shape that is convex toward the front of the vehicle so as to follow the curvature of the front portion of the front bumper 23 .

The airbag device of the embodiment includes an airbag 30 which will be described below.
The airbag 30 is formed into a bag shape by joining panels made of a base fabric such as nylon 66 fabric.
The airbag 30 is deployed and further inflated by introduction of deployment gas generated by an inflator 111 in response to the establishment of each pre-crash determination, which will be described later.
The airbag 30 deploys toward the front side of the vehicle from a center portion in the vehicle width direction at the front end of the vehicle body.
The airbag 30 is normally attached to the bumper beam 22 in a folded state (before the pre-crash determination is made), and is housed inside the front bumper 23 .
In the event of a collision, the airbag 30 breaks a weakened portion formed in the front bumper 23 and is deployed toward the front side of the vehicle, and deploys forward in front of the front bumper 23.

FIG. 2 is a schematic cross-sectional view showing the structure of an airbag in the airbag device of the embodiment.
The airbag 30 is configured by sequentially arranging a first air chamber (chamber) C1, a second air chamber C2, a third air chamber C3, and a fourth air chamber C4 in that order from the front side of the vehicle.
The airbag 30 is configured to have a gas inlet 31, a partition 32, a partition 33, a partition 34, a duct 35, an opening 36, an opening 37, a vent hole 38, and the like.

The gas inlet 31 is provided at the rear end of the airbag 30 and is a portion into which the deployment gas is blown from the inflator 111 .
The gas inlet 31 releases the introduced deployment gas into the fourth chamber C4.

The partition wall 32 is a member that separates the first air chamber C1 and the second air chamber C2.
The partition wall 33 is a member that separates the second air chamber C2 and the third air chamber C3.
The partition wall 34 is a member that separates the third chamber C3 and the fourth chamber C4.
Each of the partitions 32, 33, and 34 is formed from a flexible base fabric panel.
The partition walls 32, 33, 34 each extend in the vertical direction and in the vehicle width direction, and are arranged successively from the front side of the vehicle at intervals from one another.
The outer peripheral edges of the partitions 32 , 33 , 34 are joined to the inner surface of the skin portion of the airbag 30 over the entire periphery.
An opening in which a duct 35 is provided is formed in the center of each of the partitions 32, 33, and 34.
The partition wall 33 has an opening 37 formed therein, which will be described later.

The duct 35 is a flow path for the deployment gas G that extends in the front-rear direction of the vehicle inside the airbag 30 .
The duct 35 is configured by forming a base fabric panel into a cylindrical shape.
The rear end of the duct 35 is joined to an opening in the center of the partition wall 34 and opens in communication with the fourth air chamber C4.
The front end of the duct 35 is joined to an opening in the center of the partition wall 32 and opens in a state of communicating with the first air chamber C1.
The duct 35 has a function of supplying the development gas G introduced into the fourth chamber C4 to the first chamber C1 and the like.
The middle portion of the duct 35 passes through the second air chamber C2 and the third air chamber C3.
The inner peripheral edge of the central opening of the partition wall 33 is joined to the outer peripheral surface of the middle part of the duct 35 .

The opening 36 introduces a portion of the development gas G flowing inside the duct 35 into the third chamber C3.
The opening 36 is formed by penetrating a part of the peripheral surface of the duct 35 exposed inside the third air chamber C3.

The opening 37 introduces a portion of the development gas G introduced into the third chamber C3 into the second chamber C2.
The opening 37 is formed by penetrating the partition wall 33 that separates the second air chamber C2 and the third air chamber C3.
A plurality of openings 37 are formed in the partition wall 33 .

The vent hole 38 exhausts a portion of the development gas G introduced into the second chamber C2 to the outside (opens to the atmosphere).
A plurality of vent holes 38 are formed penetrating a surface portion of the airbag 30 that constitutes a part of the second chamber C2.
The vent hole 38 has the effect of preventing the internal pressure of the airbag 30 from becoming excessively high by discharging the expansion gas G, and not impeding the absorption of energy caused by the contraction of the airbag 30.

FIG. 3 is a block diagram showing a schematic configuration of a system for controlling the airbag device according to the embodiment.
The system for controlling the airbag device is configured to include an airbag control unit 110, an environment recognition unit 120, and the like.
Each of these units can be configured as a microcomputer having, for example, an information processing unit (processor) such as a CPU, a storage unit such as a RAM or a ROM, an input/output interface, and a bus connecting these.
In addition, each unit is connected directly or via an in-vehicle LAN such as a CAN communication system, so that they can communicate with each other.

The airbag control unit 110 issues a command to the inflator 111 to control it, thereby inflating the airbag 30 and controlling the state of the inflation.
The airbag control unit 110 functions as an airbag deployment control unit of the present invention.
The inflator 111 is a chemical (pyrotechnic) gas generating device that generates a deployment gas G for deploying the airbag 30 in response to a command from the airbag control unit 110 .
The inflator 111 is a multi-stage inflator capable of generating the deployment gas G a plurality of times at time intervals.

The airbag control unit 110 is provided with a pressure sensor 112 .
The pressure sensor 112 has a function of detecting the internal pressure of the fourth chamber C4 of the airbag 30.
The airbag control unit 110 can detect the input state of the load to the airbag 30 based on the output of the pressure sensor 112 .
The output of the pressure sensor 112 is also used to control the additional supply of deployment gas G by the inflator 111, which will be described later.

The environment recognition unit 120 recognizes the environment around the vehicle based on the outputs of various sensors.
The environment recognition unit 120 has the function of recognizing, for example, human bodies such as pedestrians and cyclists around the vehicle 1 (host vehicle), various objects such as other vehicles, buildings, trees, and terrain, road shapes (lane shapes), etc.
The environmental recognition unit 120 functions as a collision judgment section that establishes a pre-crash judgment when a collision with a human body, such as a pedestrian, a cyclist, or a motorcycle rider, or an object other than a human body, such as another vehicle, is unavoidable (when the possibility of collision is greater than a predetermined level).
The environment recognition unit 120 is connected to a stereo camera device 121, a millimeter wave radar device 122, a laser scanner device 123, etc.

The stereo camera device 121 has a pair of cameras arranged at a predetermined distance (baseline length) apart, and has the function of recognizing, for example, human bodies such as pedestrians and cyclists, and objects such as other vehicles and buildings, and also detects the relative positions of human bodies, objects, etc. in relation to the vehicle 1 using well-known stereo image processing.
The stereo camera device 121 has a function of recognizing the attributes of a subject by, for example, pattern recognition of a captured image.
For example, in the case of a human body such as a pedestrian, the system has a function for recognizing the physique, estimated weight, posture, and the like.
In addition, for example, if the object is another vehicle, it has a function of recognizing the type and size of the other vehicle (whether it is a large vehicle that is significantly heavier than vehicle 1, such as a truck, bus, or large SUV).

The millimeter wave radar device 122 is a radar device that uses radio waves in a frequency band of, for example, 30 to 300 GHz, and has the function of detecting the presence or absence of human bodies, objects, etc., and the relative positions of human bodies, objects, etc. in relation to the vehicle 1.
The laser scanner device (LIDAR) 123 has the function of scanning the area around the vehicle 1, for example by emitting pulsed near-infrared laser light, and detecting the presence or absence of human bodies, objects, etc., and the relative position and shape of human bodies, objects, etc. in relation to the vehicle 1 based on the presence or absence of reflected light and the time difference until the reflected light returns.
The environmental recognition unit 120 is capable of recognizing the type of collision with a human body, object, etc. (e.g., the velocity vector relative to the vehicle 1 of the collision object, the collision position relative to the vehicle 1, etc.) and the attributes of the collision object (the physique of the human body, the model of the other vehicle, etc.) when a collision with a human body, such as a pedestrian, or an object, such as another vehicle, is unavoidable (when a pre-crash judgment is established).

The functions, actions, and effects of the airbag device of the embodiment will be described below.
When the environment recognition unit 120 recognizes a human body such as a pedestrian or a cyclist approaching from the front of the vehicle 1, or an object other than a human body, it estimates the possibility of a collision occurring using known pre-crash judgment logic, and if the estimated possibility is equal to or greater than a preset threshold, it establishes a pre-crash judgment that a collision is unavoidable.

In response to the establishment of the pre-crash determination by the environment recognition unit 120, the airbag control unit 110 issues a command to the inflator 111 to generate gas G for expansion.
When the deployment gas G is introduced into the airbag 30 , the airbag 30 breaks a weak portion of the front bumper 23 and deploys forward of the vehicle 1 .

The pressure (internal pressure) of the expansion gas G inside the airbag 30 during expansion is the highest in the fourth chamber C4, in which the gas inlet 31 is provided, among the four air chambers.
The first chamber C1, to which the deployment gas G is introduced from the fourth chamber C4 via the duct 35 and which is not provided with a vent hole or the like, becomes pressurized next to the fourth chamber C4.
The third chamber C3, into which the development gas G is introduced from the opening 36 on the side of the duct 35, has a lower pressure than the first chamber C1, into which the development gas G is introduced straight by the duct 35, because the pressure loss (pressure drop) in the introduction flow path of the development gas G is large and development gas G also flows out from the opening 37 into the second chamber C2.
The second air chamber C2 has the lowest pressure of the four air chambers because the deployment gas G is introduced through the fourth air chamber C4, duct 35, opening 36, third air chamber C3, and opening 37 in that order, resulting in a large pressure loss in the introduction flow path. Furthermore, the deployment gas G is also exhausted from the vent hole 38.
That is, the internal pressure of each air chamber of the airbag 30 becomes higher in the order of the fourth air chamber C4, the first air chamber C1, the third air chamber C3, and the second air chamber C2.

When an impact object (a pedestrian, for example) collides with the front part of the airbag 30 that has completed deployment and a compressive load acts on the airbag 30 in the fore-and-aft direction, the second air chamber C2, which has the lowest pressure among the four air chambers and has the lowest compressive rigidity in the fore-and-aft direction, first contracts in the fore-and-aft direction while venting the deployment gas G from the vent hole 38.
Following or simultaneously with the contraction of the second chamber C2, the third chamber C3 contracts in the front-rear direction while transferring the deployment gas G from the opening 37 to the second chamber C2.

On the other hand, while the second air chamber C2 and the third air chamber C3 are contracting, the first air chamber C1, which comes into direct contact with pedestrians, etc., and the fourth air chamber C4, which forms the base on the vehicle body side, are maintained at a higher internal pressure than the second air chamber C2 and the third air chamber C3.
This makes it possible to improve the shape stability when the airbag 30 is compressed in the vehicle front-rear direction due to contraction of the second air chamber C2 and the third air chamber C3.

The airbag control unit 110 monitors the internal pressure of the fourth chamber C4 using a pressure sensor 112, and issues a command to the inflator 111 to supply additional deployment gas G so that the internal pressure of the fourth chamber C4 becomes equal to or higher than a predetermined level.
This reduces the internal pressure of the fourth chamber C4, which reduces the rigidity of the airbag 30, and prevents the airbag 30 from being undesirably deformed, such as folded or collapsed.

As described above, according to this embodiment, the following effects can be obtained.
(1) When an object such as a pedestrian collides with the airbag 30, the second air chamber C2, which is located in the middle and has a low pressure, is first deflated, and then the third air chamber C3 and the first air chamber C1, which have relatively high internal pressure, are successively deflated, thereby making it possible to effectively absorb energy.
Furthermore, by making the first air chamber C1 and the fourth air chamber C4 located at the front end and the rear end higher pressure than the second air chamber C2 and the third air chamber C3 located in the middle portion, the shape stability of these air chambers is improved, and deformation of the airbag 30 (e.g., folding or collapsing of the airbag 30) that would cause the contact condition with the object of collision or energy absorption to become unstable can be suppressed.
In addition, it is possible to gradually increase the reaction force applied from the airbag 30 to the collision object from an initial relatively low state, thereby preventing the collision object from receiving a high reaction force in the early stages of the collision.
As a result, the collision energy is effectively absorbed, and the collision object is pushed forward of the vehicle 1, accelerating it, reducing the relative speed between the collision object and the vehicle body, thereby minimizing damage to the collision object.
(2) By varying the pressure loss in the supply flow path of the expansion gas G from the inflator 111 to the first air chamber C1 to the fourth air chamber C4 and varying the internal pressure of each air chamber C1 to C4, the above-mentioned effects can be obtained with a simple device configuration using a single inflator 111.
(3) By introducing the deployment gas G into the second air chamber C2, which has the lowest pressure, via the third air chamber C3, the pressure loss in the supply flow path of the deployment gas G to the second air chamber C2 can be increased with a simple configuration, and the internal pressure of the second air chamber C2 can be made low.
(4) By making each of the air chambers C1 to C4 communicable and providing a vent hole 38 only in the second air chamber C2 located in the middle portion, excess deployment gas G can be released to the outside through the vent hole 38, thereby preventing the internal pressure of the second air chamber C2, which should be kept low, from becoming high pressure due to compressive deformation of the air chamber or the inflow of gas from the third air chamber C3, etc., which would result in the impairment of the above-mentioned functions.
(5) Since the inflator 111 additionally supplies the expansion gas G so that the internal pressure of the fourth chamber C4 becomes a predetermined level or higher, it becomes possible to maintain the internal pressure of the fourth chamber C4 at a predetermined level or higher regardless of the outflow of the expansion gas G from the vent hole 38 after a collision, thereby ensuring the shape stability of the airbag 30 before and after the collision.

(Modification)
The present invention is not limited to the above-described embodiment, and various modifications and variations are possible, which are also within the technical scope of the present invention.
(1) The configurations of the airbag device and the vehicle are not limited to those of the above-described embodiments and may be modified as appropriate.
For example, the structure, shape, material, manufacturing method, arrangement, and number of each member and part that constitutes these, as well as the specific content of various controls, are not limited to those in the respective embodiments and can be changed as appropriate.
(2) The method of performing the pre-crash determination and the method of determining the type of collision are not limited to the methods described in the respective embodiments and may be modified as appropriate.
(3) The number of air chambers inside the airbag in the embodiment, the configuration of the introduction flow path of the deployment gas to each air chamber, the arrangement of the vent holes, etc. are merely examples and can be changed as appropriate. The pressure distribution of each air chamber can also be changed as appropriate. For example, in the embodiment, among the air chambers provided in the middle portion, the front air chamber is at a lower pressure than the rear air chamber, but the rear air chamber may be at a lower pressure.

REFERENCE SIGNS LIST 1 vehicle 10 vehicle interior 20 engine compartment 21 front side frame 22 bumper beam 23 front bumper 30 airbag C1 first air chamber C2 second air chamber C3 third air chamber C4 fourth air chamber 31 gas inlet 32 bulkhead 33 bulkhead 34 bulkhead 35 duct 36 opening 37 opening 38 vent hole 110 airbag control unit 111 inflator 112 pressure sensor 120 environment recognition unit 121 stereo camera device 122 millimeter wave radar device 123 laser scanner device G deployment gas

Claims (5)

An airbag that deploys forward from the front of the vehicle body;
a collision determination unit that establishes a pre-crash determination when the possibility of a collision is equal to or greater than a predetermined threshold;
an airbag deployment control unit that issues a command to an inflator in response to the pre-crash determination to introduce deployment gas into the airbag and deploy the airbag,
The airbag is configured by arranging a plurality of air chambers having different internal pressures when deployed in the front-rear direction of the vehicle,
an airbag device, wherein among the plurality of air chambers of the airbag, the internal pressure of the air chambers located at the front end and the rear end is made higher than the internal pressure of the air chamber located in a middle portion. 2. The airbag device according to claim 1, wherein the plurality of air chambers of the airbag are supplied with the deployment gas from a common inflator, and the internal pressures of the plurality of air chambers are made different by making different pressure losses in an introduction flow path of the deployment gas from the inflator. 3. The airbag device according to claim 1, wherein the expansion gas is introduced into some of the air chambers arranged in the middle portion of the plurality of air chambers of the airbag via the insides of the other air chambers. 4. The airbag device according to claim 1, wherein the plurality of air chambers of the airbag are configured to allow the deployment gas to communicate with each other, and a vent hole for releasing the deployment gas to the outside is provided only in a portion of the air chambers located in the middle portion. 5. The airbag device according to claim 1, wherein the inflator additionally supplies deployment gas so that an internal pressure of at least one of the air chambers located at a front end portion and a rear end portion of the plurality of air chambers of the airbag becomes equal to or higher than a predetermined internal pressure after the airbag is deployed.

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