The present invention relates to a side airbag apparatus that protects an occupant seated in a vehicle seat from an impact by deploying and inflating an airbag on a side of the occupant when an impact is applied to a vehicle.
A side airbag apparatus having an airbag and an inflator is widely known for protecting an occupant from an impact when the impact is applied to a vehicle from a side to a vehicle seat in which the occupant is seated, for example, due to a side collision. In the side airbag apparatus, an airbag is installed in a seat back of a vehicle seat in a folded state together with an inflator. When an impact is applied from the side on a member forming a side of a vehicle (body side portion), for example, a side door, an inflator of the side airbag apparatus supplies inflation gas to an inflation portion of an airbag main body, which forms the outer shape of the airbag. The inflation gas inflates the inflation portion, so that the airbag main body is deployed and inflated. The airbag is projected forward from the vehicle seat with a part of the airbag remaining in the seat back. The airbag main body is deployed and inflated in a narrow space between the occupant and the body side portion. The deployed and inflated airbag main body is located between the occupant and the body side portion to restrain the occupant and reduces the impact from the side transmitted to the occupant via the body side portion.
In the human body, the lumbar region and the shoulder region are generally known to have a better impact resistance than the thorax. Therefore, in the case of a side airbag apparatus that protects an occupant in a large area ranging from the lumbar region to the shoulder region, it is preferable that an airbag main body protect the thorax by softening the impact to the thorax more than the impact to the lumbar region and the shoulder region.
In this regard, Japanese Laid-Open Patent Publication No. 2010-137615 discloses a side airbag apparatus that has an inflation portion divided into a plurality of inflation chambers. In the side airbag apparatus, an inflation portion 132 of an airbag main body 131 is divided into a first inflation chamber 134, a second inflation chamber 135, and a pair of upper and lower third inflation chambers 136, 137 as illustrated in FIG. 21. The first inflation chamber 134 receives inflation gas from the inflator 133 to be deployed and inflated. The second inflation chamber 135 is located in front of the first inflation chamber 134 with a vertical partition 138 in between. The upper third inflation chamber 136 is located above the first inflation chamber 134 and the second inflation chamber 135 with a lateral partition 139 in between. The lower third inflation chamber 137 is located below the first inflation chamber 134 with a lateral partition 141 in between.
The vertical partition 138 is formed by an inner tube incorporating the inflator 133. The vertical partition 138 has an opening 142, which connects the first inflation chamber 134 and the second inflation chamber 135 with each other. The upper lateral partition 139 has an opening 143, which connects the first inflation chamber 134 and the third inflation chamber 136 with each other, and a check valve 144, which prevents inflation gas in the third inflation chamber 136 from flowing back to the first inflation chamber 134 through the opening 143. The lower lateral partition 141 has an opening 145, which connects the first inflation chamber 134 and the third inflation chamber 137 with each other, and a check valve 146, which prevents inflation gas in the third inflation chamber 137 from flowing back to the first inflation chamber 134 through the opening 145.
According to the above described side airbag apparatus, inflation gas discharged from the inflator 133 is supplied to the first inflation chamber 134. Some of the inflation gas is supplied to the second inflation chamber 135 through the opening 142. Also, some of the inflation gas is supplied to the third inflation chamber 135 through the opening 143 and the check valve 144, and is supplied to the third inflation chamber 137 through the opening 145 and the check valve 146. Also, the check valves 144, 146 cause the internal pressures of the first inflation chamber 134 and the second inflation chamber 135 to be lowered and the internal pressures of the third inflation chambers 136, 137 to be raised. This prevents the internal pressures of the first inflation chamber 134 and the second inflation chamber 135 from being excessively increased at the restraint of the occupant. Also, the internal pressures of the third inflation chambers 136, 137, which have been raised to level appropriate for protecting the shoulder region and the lumbar region, are maintained.
In this manner, the third inflation chambers 136, 137 are deployed and inflated with high internal pressures beside the shoulder region and the lumbar region, which have a relatively high impact resistance in the side of the occupant, and the first inflation chamber 134 and the second inflation chamber 135 are deployed and inflated with low internal pressures beside the thorax, which has a relatively low impact resistance. Thus, the inflation portion 132 is deployed and inflated with a pressure distribution appropriate for the impact resistance of the side of the occupant, so that body parts of the occupant (the shoulder region, the lumbar region, and the thorax) are effectively protected from an impact.
In the above described airbag apparatus, when the airbag main body 131 is pressed against the occupant by the body side portion, which bulges inward due to an impact from the side, the occupant receives the load of the impact via the airbag main body 131. The load is expressed by the product of the area by which the occupant receives the pressure from the airbag main body 131 (the pressure receiving area of the occupant on the side facing the airbag main body 131) and the internal pressure of the airbag main body 131. From a viewpoint of protection of the occupant from impact, the load preferably reaches a predetermined value in a short time after the body side portion starts bulging inward, and is maintained at the value irrespective of the amount of bulging of the body side portion.
However, in the side airbag apparatus disclosed in Japanese Laid-Open Patent Publication No. 2010-137615, inflation gas starts flowing to the second inflation chamber 135 through the opening 142 in an initial state of inflation of the first inflation chamber 134, and the second inflation chamber 135 is deployed and inflated together with the first inflation chamber 134. Thus, as the amount of an inward bulging of the body side portion, the internal pressure and the pressure receiving rear are increased. The load that the occupant receives from the airbag main body 131 is gradually increased as the inward bulging of the body side portion progresses. The load reaches the predetermined value only after the body side portion bulges inward by a certain extent. Further, the load continues to increase after reaching the predetermined value and eventually exceeds the predetermined value. As a result, until the load reaches the predetermined value, the sufficient protection of the occupant from the impact is not started. After the load reaches the predetermined value, the occupant receives a load greater than the predetermined value via the airbag main body 131. Thus, there is still room for improvement regarding the restraint and protection of the occupant.
The matters described above are common to a side airbag apparatus that only has one of the third inflation chambers 136, 137.
Accordingly, it is an objective of the present invention to provide a side airbag apparatus capable of improving the occupant restraint and protection performance compared to an airbag apparatus in which an opening is provided between a first inflation chamber and a second inflation chamber, and an opening and a check valve are provided between the first inflation chamber and a third inflation chamber.
To achieve the foregoing objective, and in accordance with one aspect of the present invention, a side airbag apparatus including an airbag main body, a pressure regulator valve, and a check valve is provided. The airbag main body includes an inflation portion. The inflation portion is inflated by inflation gas supplied thereto in response to an impact applied to a side of a vehicle seat. The airbag main body is deployed forward on the side of the vehicle seat. The inflation portion includes a first inflation chamber, a second inflation chamber, a vertical partition, a third inflation chamber, and a lateral partition. The first inflation chamber is deployed and inflated by being supplied with the inflation gas. The second inflation chamber is located in front of and adjacent to the first inflation chamber. The vertical partition separates the first inflation chamber and the second inflation chamber from each other. The third inflation chamber is adjacent to and located above or below the first inflation chamber. The third inflation chamber is deployed and inflated by the inflation gas with an internal pressure that is higher than the inflation pressure of the first inflation chamber. The lateral partition separates the first inflation chamber and the third inflation chamber from each other. The vertical partition and the lateral partition each have an opening. The pressure regulator valve is provided in the vertical partition. When the first inflation chamber is inflated before starting restraining an occupant, the pressure regulator valve is closed to restrict the inflation gas from flowing from the first inflation chamber to the second inflation chamber through the opening. When the first inflation chamber restrains the occupant, the pressure regulator valve opens in response to a change in the tensed state of the vertical partition due to an applied external force generated by the restraint, thereby cancelling the restraint. The check valve is provided in the lateral partition to restrict flow of the inflation gas from the third inflation chamber to the first inflation chamber.
Other aspects and advantages of the present invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.