Land vehicles – Wheeled – Attachment
Reexamination Certificate
1999-05-26
2001-06-05
Dickson, Paul N. (Department: 3618)
Land vehicles
Wheeled
Attachment
C280S739000, C280S742000
Reexamination Certificate
active
06241279
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an air bag device in which an inflator is housed in a retainer to which a periphery of an opening of a folded air bag is fixed, and the air bag is inflated to develop by a gas which is generated by the inflator when a vehicle collides or the like (in other words, a vehicle is subject to a predetermined rapid acceleration/deceleration or more), thereby restraining an occupant.
2. Description of the Prior Art
In an air bag device of the prior art, a vent hole is formed in an air bag which is to be inflated by a gas generated by an inflator, so that the gas is partly discharged through the vent hole to control the internal pressure of the air bag. A structure of such an air bag device is proposed in which a vent hole is closed by a membrane so that an air bag is rapidly inflated in an initial development stage, and, when the development is completed and the internal pressure of the air bag is raised, the membrane is broken to discharge a gas through the vent hole, thereby gently restraining an occupant. Such as conventional air bag device can be seen in a Japanese tility Model Unexamined Publication (Kokoku) No. HEI. 5-6206.
In addition, a Japanese Patent Unexamined publication No. EI. 9-301115 suggests another air bag device in which two inflators are disposed, both the two inflators are ignited when no passenger exists in the vicinity of the air bag device, and only one of the inflators is ignited when a passenger exists in the vicinity of the air bag device, whereby the development speed and internal pressure of an air bag are controlled in accordance with the position of a passenger (see Japanese Patent Publication (Kokai) HEI 9-301115).
The conventional air bag device disclosed in the Japanese Utility Model Unexamined Publication No. HEI. 5-6206 has problems. One of the problems is that the pressure at which the membrane is broken is easily dispersed, and hence it is difficult to correctly open the vent hole when the internal pressure reaches the predetermined value. The other problem is that it is difficult to accurately control the internal pressure, because the vent hole which has been once opened cannot be again closed.
Further, the conventional air bag device disclosed in the Japanese Patent Publication (Kokai) HEI. 9-301115 also has problems. One of the problem is that the two inflators are required and hence the number of parts is increased, thereby increasing the production cost. The other problem is that the control cannot be finely conducted, because the development of the air bag is controlled in only two stages (that is, one stage in which a single inflator is ignited, or the other stage in which both inflators are ignited).
SUMMARY OF THE INVENTION
The present invention has been conducted in view of the above-discussed circumstances.
Therefore, it is an object of the present invention to provide an air bag device having a simple structure which enables a vent hole of an air bag device to be correctly opened and closed.
In addition, it is another object of the present invention to provide an air bag device capable of correctly controlling the internal pressure of an air bag by changing the amount of a gas which is discharged through a vent hole when the air bag develops.
The above-mentioned object can be attained by an air bag device according to a first aspect of the present invention in which an inflator is housed in a retainer to which a periphery of an opening of a folded air bag is fixed, and the air bag is inflated to develop by a gas which is generated by the inflator when a vehicle collides, thereby restraining an occupant, wherein a vent hole formed in the retainer is opened and closed by an actuator configured by a piezoelectric element.
According to this configuration, the amount of the gas which, when a vehicle collides, is generated by the inflator and discharged through the vent hole can be arbitrarily controlled by changing the opening degree of the vent hole by the actuator. Therefore, the development speed of the air bag, the degree of the restraining force of the air bag, the contraction speed of the air bag, and the like can be arbitrarily set in accordance with the condition of the collision and the state of an occupant. Particularly, an actuator configured by a piezoelectric element is simpler in structure and less troublesome than a motor or a solenoid. Therefore, a sure operation can be guaranteed while enabling the number of parts of the actuator to be reduced and the production cost to be lowered.
In the above configuration, preferably, the actuator may be a plate-like piezoelectric element which is placed so as to cover the vent hole, and in which one end is fixed to the retainer.
According to this configuration, the plate-like piezoelectric element having a very simple structure can be provided with both a function as a valve element which opens and closes the vent hole, and that as an actuator which drives the valve element. Consequently, the actuator can be miniaturized and reduced in production cost.
In the above configuration, preferably, a protector configured by a metal plate may be stacked on the piezoelectric element.
According to this configuration, the durability of the piezoelectric element which itself is fragile can be enhanced by stacking thereon the protector configured by a metal plate.
In the above configuration, preferably, plural vent holes may be formed in the retainer, a valve plate having plural openings respectively corresponding to the vent holes may be slidably supported on the retainer, and the valve plate may be slid by the actuator which is configured by stacking piezoelectric elements, thereby opening or closing the vent hole.
According to this configuration, the combination of the plural vent holes formed in the retainer and the plural openings formed in the valve plate enables the opening degree of the vent holes to be changed from a fully closed state to a fully opened state or vice versa, only by moving the valve plate with a small stroke. Therefore, miniaturization of the actuator and improvement of the responsibility can be simultaneously attained.
The objects can be attained by an air bag device according to a second aspect of the present invention in which an inflator is housed in a retainer to which a periphery of an opening of a folded air bag is fixed, and the air bag is inflated to develop by a gas which is generated by the inflator when a vehicle collides, thereby restraining an occupant, wherein the device comprises: plural vent holes formed in the retainer; a valve plate in which plural openings respectively corresponding to the plural vent holes are formed; and an actuator which slides the valve plate along the retainer to cause the plural openings to oppose the plural vent holes.
According to this configuration, since the valve plate is slid by the actuator, so as to change the opening degree of the vent holes, the amount of the gas which, when a vehicle collides, is generated by the inflator and discharged through the vent holes can be arbitrarily controlled. Therefore, the development speed of the air bag, the degree of the restraining force of the air bag, the contraction speed of the air bag, and the like can be arbitrarily set in accordance with the condition of the collision and the state of an occupant. Particularly, the combination of the plural vent holes formed in the retainer and the plural openings formed in the valve plate enables the opening degree of the vent holes to be changed from a fully closed state to a fully opened state or vice versa, only by moving the valve plate with a small stroke. Therefore, miniaturization of the actuator and improvement of the responsibility can be simultaneously attained.
In the above configuration, preferably, the plural vent holes may be arranged in a circumferential direction, and the valve plate may be reciprocally rotated by the actuator.
According to this configuration, the plural vent holes which are arranged in a circumferential direction are opened
Dickson Paul N.
Honda Giken Kogyo Kabushiki Kaisha
Sughrue Mion Zinn Macpeak & Seas, PLLC
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