Airbag and airbag device

An airbag includes a bag portion to be inflated at a location close to an occupant and a pressure sensor mounted on an inner surface of the bag portion. A harness is connected to the pressure sensor to extend along the inner surface of the bag portion. An airbag device includes the airbag and a gas generator for inflating the airbag. Accordingly, high-speed air flow from the gas generator does not affect the pressure sensor, and it is possible to detect the pressure precisely.

BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT

The present invention relates to an airbag and an airbag device installed in, for example, a vehicle. More specifically, the present invention relates to an airbag and an airbag device having a sensor for detecting an internal pressure of the airbag.

An airbag device installed in an automobile comprises an airbag and a gas generator for inflating the airbag. In case of automobile collision, the gas generator ejects gas and the airbag is inflated to receive and protect an occupant.

Japanese Patent Publication (KOKAI) No. 09-30367 has disclosed an airbag in which a pressure sensor detects an internal pressure of the airbag in order to monitor a state of inflation of the airbag. The pressure sensor is installed at a filter for filtering gas from a gas generator. When the airbag is inflated, the gas from the gas generator passes the filter at a high speed toward an inside of the airbag. Therefore, when the pressure sensor is installed at the filter, it is difficult to accurately detect the pressure due to Karman's vortex and Venturi action caused by the gas flow.

Accordingly, it is an object of the present invention to provide an airbag having a pressure sensor for detecting the internal pressure of the airbag with high precision, and an airbag device comprising the airbag.

SUMMARY OF THE INVENTION

According to the present invention, an airbag comprises a bag portion to be inflated at a location close to an occupant and a pressure sensor mounted on an inner surface of the bag portion. An airbag device comprises the airbag and a gas generator for inflating the airbag.

In the airbag and airbag device of the invention, the pressure sensor is disposed on the inner surface of the bag portion. Accordingly, high-speed air flow from the gas generator does not affect the pressure sensor, and it is possible to detect the pressure with high precision.

According to the present invention, it is desirable to provide a harness connected to the pressure sensor and routed along the inner surface of the bag portion. With this arrangement, the harness does not interfere when the airbag is folded, thereby making it easy to fold the airbag. Further, when the airbag is inflated, the harness moves with the airbag, thereby preventing excessive stress from exerting upon a localized portion of the harness.

According to the present invention, at least a portion of the harness is routed along the folding portion of the airbag. In general, a slight gap is formed along a folding line of the airbag. At least a part of the harness is disposed in the gap, so that the airbag does not become bulky when the airbag is folded.

According to the present invention, it is desirable to dispose the pressure sensor at a portion of the airbag other than that where the airbag contacts the occupant or a vehicle body. With this arrangement, when the airbag contacts the occupant or the vehicle body, it is possible to eliminate shock, vibration, pressure, or the like applied to the pressure sensor, thereby preventing damage on the pressure sensor and a variation in detecting the pressure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereunder, embodiments of the present invention will be explained with reference to the accompanying drawings.FIG. 1is a perspective view of an airbag device when an airbag is inflated according to an embodiment of the present invention.FIG. 2is a perspective view of the airbag in a folded state.FIGS. 3(a) and3(b) are views showing an operation of the airbag device, whereinFIG. 3(a) shows an inside of a vehicle before the airbag is inflated, andFIG. 3(b) shows the inside of the vehicle when the airbag is inflated.

As shown inFIG. 3(a), a passenger airbag device10is disposed in an airbag device installation opening (not shown) formed in a top surface of an instrument panel1. The airbag device10comprises an airbag12, a container14for accommodating the airbag12in a folded state, a gas generator16for inflating the airbag12, and pressure sensors18for detecting an internal pressure of the airbag12when the airbag12is inflated. An airbag-inflation opening (not shown) is disposed in a top surface of the container14, and a lid (not shown) covers the opening. When the airbag12is inflated, the lid starts opening, thereby opening the airbag-inflation opening. A top surface of the lid is flush with the top surface of the instrument panel1.

As shown inFIG. 3(b), the airbag12is inflated in a space defined by the instrument panel1, the windshield2, and a passenger, so that a passenger-facing surface12creceives the passenger. Reference numerals12dand12edenote left and right side portions of the airbag12in an inflated state.

A gas inlet (not shown) is formed near a rear end of the airbag12in a direction of the inflation. A peripheral edge of the gas inlet is connected to the airbag-inflation opening of the container14. The gas generator16is disposed in the container14. As shown inFIG. 1, the gas generator16has a rod shape, and is disposed in the container14so that a longitudinal direction thereof is aligned in the width direction of the vehicle.

The pressure sensors18are mounted to an inner surface of a side portion12dof the airbag12at an inside center of the vehicle. In the embodiment, two pressure sensors18are mounted at different locations in the vertical direction.

The pressure sensors18are disposed at locations sufficiently away from a gas inlet and a front portion12cof the airbag12, respectively. Accordingly, it is possible to reduce influences from gas flow introduced into the airbag12from the gas generator16and an impact of the passenger plunging into the front portion12cof the airbag12. In addition, the locations of the pressure sensors18are away from a bottom portion12aand a top portion12bof the airbag as well. Accordingly, it is possible to reduce influences from an impact of the bottom portion12acontacting the instrument panel1and an impact of the top portion12bcontacting the windshield2.

In the embodiment, each of the pressure sensors18is disposed at an intermediate location between the gas inlet and the passenger-facing surface12cof the airbag12or closer to the passenger than the intermediate location.

An end of a harness18ais connected to each of the pressure sensors18. The harness18ais routed or led along the inner surface of the side portion12dof the airbag12, and extends from the pressure sensors18towards the rear end of the airbag12. Reference numeral18bdenotes a fastener for fastening the harness18ato the inner surface of the side portion12dof the airbag. The other end of the harness18ais drawn into the container14through the gas inlet. A middle portion of the harness18ais routed along a folding portion of the airbag12(afolding line L described later). A process of folding the airbag12will be described later.

A vent hole (not shown) is disposed in a wall surface of the container14for discharging gas in the inflated airbag12to outside. A closing member is provided for closing the vent hole until an internal pressure of the airbag12reaches a predetermined value. The closing member is provided with an automatic opening-and-closing mechanism. The automatic opening-and-closing mechanism is provided with a controller for automatically opening and closing the closing mechanism based on detected values from the pressure sensors18. The other end of the harness18ais connected to the controller.

The airbag12is folded and accommodated in the container14, and the lid is mounted to the airbag-bulging opening of the container14, thereby constituting the airbag device10.

A process of folding the airbag12will be described next. In the process of folding the airbag12, first, as shown inFIG. 2, the left and right side portions12dand12eof the airbag12are folded in zigzag forms along the folding lines L arranged with an interval in the forward-and-backward direction of the airbag12, so that a vertically elongated primary-stage folded member is formed. At this time, the airbag12is folded so that one folding line L passes on the pressure sensors18or near the pressure sensors18.

As mentioned above, the harness18aconnected to the pressure sensors18is routed along the folding lines L. More specifically, the harness18aextends between the pressure sensors18along the folding line L passing on the pressure sensors18. The harness18aextends towards the rear end of the airbag12, and changes a direction perpendicularly to extend along another folding line L adjacent to the previous folding line L. Then, the harness18asuccessively changes a direction in a zigzag form and extends toward the rear end of the airbag12along another adjacent folding line L, thereby drawing out into the container14from the gas inlet. Then, the primary-stage folded member is folded from top and bottom ends towards the airbag-inflation opening of the container14, thereby forming a final-stage folded member. The final-stage folded member is accommodated in the container14from the airbag-inflation opening.

In the airbag device10having such a structure, when the vehicle collides, the gas generator16ejects gas. The gas from the gas generator16inflates the airbag12in front of the passenger for receiving the passenger as shown inFIG. 3(b).

When the pressure sensors18detect the internal pressure of the airbag12above a predetermined value, the automatic opening-and-closing mechanism of the closing member is operated to open the vent hole. The gas in the airbag12is discharged from the vent hole in order to absorb an impact. On the other hand, when the internal pressure of the airbag12is below the predetermined value, the automatic opening-and-closing mechanism closes the vent hole, thereby preventing an excessive reduction in the internal pressure of the airbag12. Incidentally, the automatic opening-and-closing mechanism may have a desired mechanism, such as Japanese Patent Publication No. 2003-34222 (EP 1279574A1). The structure of the automatic opening-and-closing mechanism disclosed in Japanese Patent Publication No. 2003-34222 is incorporated herein.

In the airbag device10, the pressure sensors18are disposed on the inner surface of the airbag12. Accordingly, high-speed air flow from the gas generator16does not affect the pressure sensors18, and the pressure is detected with high precision.

In the airbag device10, the pressure sensors18are disposed on the side portion12dof the airbag12at the locations where the airbag12does not contact the passenger and the vehicle body including the instrument panel1, the windshield2, and side surfaces in the vehicle. Therefore, when the airbag12contacts the passenger or the vehicle body, the pressure sensors18are not subjected to, for example, shock, vibration, or pressure, thereby eliminating damage of the pressure sensors18and a variation in the detected pressure.

In the embodiment, the harness18aconnected to the pressure sensors18is routed or led along the inner surface of the side portion12dof the airbag12. Accordingly, the harness18adoes not interfere when the airbag12is folded, so that the airbag12is properly folded. In addition, the harness18amoves in accordance with the airbag12, so that excessive stress is not exerted upon a localized portion of the harness18a.

In the embodiment, the middle portion of the harness18ais routed along the folding portion (folding line L) of the airbag12. In general, a slight gap is formed along the folding portion of the airbag12. Accordingly, the harness18ais disposed in such a gap, and the airbag12does not become bulky.

In the embodiment, two pressure sensors18are disposed on the inner surface of the side portion12dof the airbag12at different locations in the vertical direction. The number of the pressure sensors, an arrangement and the like are not limited to the embodiment. The process of folding the airbag12and the method of routing the harness18aconnected to the pressure sensors18are not limited to those in the embodiment.

Alternatively, as shown inFIG. 4, when the airbag12is folded, first, the left and right side portions12dand12eof the airbag12are folded in a zigzag form along a plurality of folding lines (not shown) arranged with an interval in the vertical direction of the airbag12, so that the primary-stage folded member extending in the forward-and-backward direction is formed.

In this embodiment, the pressure sensors18are disposed at locations where one of the folding lines passes or close thereto. The harness18aconnected to the pressure sensors18is routed along the folding line toward the rear end of the airbag12.

The other structural features of the embodiment are the same as those of the embodiment shown inFIGS. 1 to 3(b). Accordingly, reference numerals same as those inFIGS. 1 to 3(b) denote corresponding parts shown inFIG. 4.

InFIG. 5, in folding the airbag12, first, the airbag12is spread in a flat form toward a left end and a right end thereof. The left end and the right end are rolled leftwards and rightwards, respectively, toward the center, so that the primary-stage folded member extending in the forward-and-backward direction is formed.

In this embodiment, the pressure sensors18are not disposed at the folding line of the airbag12. The pressure sensors18are disposed on the inner surface of a substantially flat portion, i.e. an outermost portion, of the primary-stage folded member. The harness18aconnected to the pressure sensors18is routed along the inner surface of the substantially flat portion, i.e. an outermost portion, of the primary-stage folded member.

The other structural features of this embodiment are the same as those of the embodiment shown inFIGS. 1 to 3(b).

FIG. 6is a side view of an airbag device of another embodiment of the present invention. In this embodiment, an airbag device10A is mounted to a steering wheel30. Reference numeral32denotes a steering column to which the steering wheel30is mounted. The airbag device10A comprises a circular airbag12A to be inflated for covering a front surface of the steering wheel30. A hub30aof the steering wheel30has a box-shape with a front opening. The inflated airbag12A is attached to the hub30athrough a retainer (not shown) at a center of a rear portion thereof. The retainer is provided with a gas generator (not shown) for inflating the airbag12A. When the airbag12A is inflated with the gas from the gas generator, a peripheral edge of the airbag12A extends outwardly over a rim30bof the steering wheel30.

The pressure sensor18is mounted to the peripheral edge of the airbag12A on an inner surface of the rear portion of the airbag12A where the driver does not face. The harness18aconnected to the pressure sensor18is disposed along the inner surface of the airbag12A.

In the airbag device10A, the airbag12A is folded and accommodated in the hub30a, and a module cover (not shown) is mounted to the front side of the hub30aso as to cover the airbag12A. When the vehicle collides, the gas generator ejects gas to inflate the airbag12A for covering the front surface of the steering wheel30, so that the airbag12A receives and protects the driver.

In the airbag device10A, the pressure sensor18is disposed on the inner surface of the side peripheral edge of the airbag12A. Accordingly, high-speed air flow from the gas generator does not affect the pressure sensor18, and the pressure is detected with high precision.

In the airbag device10A, the pressure sensor18is disposed on the peripheral edge of the airbag12A, so that the pressure sensor18does not contact the driver and the vehicle body including the steering wheel30. Therefore, when the airbag12A contacts the driver or the vehicle body, the pressure sensor18is not subjected to shock, vibration, pressure, and the like, thereby eliminating damage on the pressure sensor and a variation in the detected pressure.

In this embodiment, the harness18aconnected to the pressure sensor18is routed or led along the inner surface of the airbag12A. Accordingly, the harness18adoes not interfere when the airbag12A is folded, so that the airbag is properly folded. In addition, the harness18amoves in accordance with the airbag12A, thereby eliminating excessive stress applied upon a localized portion of the harness18a.

The embodiments represent preferred forms of the present invention, so that the present invention is not limited to these embodiments. For example, in the embodiments, the present invention is applied to the airbag and the airbag device for a passenger and a driver in a vehicle. Alternatively, the present invention may be applied to an airbag and airbag device for various other purposes.

As described in detail above, according to the present invention, it is possible to provide the airbag and the airbag device in which the internal pressure is detected with high precision.