Inflatable seat belt with leak detection device

Abstract

An inflatable seat belt apparatus is formed of an inflatable portion which is usually maintained in a band shape and has an envelope shaped elastic inflatable member inflated and deployed in a rough spindle shape by introducing gas generated by a first gas generating device. The gas generating device operates in case of exceeding a predetermined threshold. A webbing includes the inflatable portion and extends over at least a range directly contacting with an occupant. A tongue is fixed to an end of the inflatable portion and includes a gas path extending from the gas generating device. A buckle is detachably engaged with the tongue. The envelope shaped inflatable member is inflated in a predetermined shape by introducing gas for a leak testing from a second gas generating device when the tongue is engaged with the buckle, and is inspected whether or not the gas leaks by a gas leak detecting device disposed in the gas path. A state of the damage is inspected.

Description

BACKGROUND OF THE INVENTION

The present invention relates to an inflatable seat belt apparatus, more particularly to an inflatable seat belt, wherein a webbing of a seat belt apparatus to restrain an occupant has an inflatable portion formed in an envelope shape which is usually maintained in a band shape and is inflated in a predetermined shape by high temperature gas spouted from gas generating means at a crash. In the invention, the inflatable seat belt can be inspected automatically whenever the occupant wears the seat belt as to whether or not the inflatable portion is damaged.

Presently, a seat belt apparatus is necessary for a vehicle or the like as an apparatus for securing an occupant's body, which restrains the occupant from sudden movement by an deceleration and an impact occurred at a crash.

Such a seat belt apparatus comprises a normal webbing ("a webbing" is used hereinafter as a woven belt made of a normal fabric which has approximately a 50 mm width and is provided by Japanese Industrial Standard in this specification), a retractor (hereinafter, ELR: Emergency Locking Retractor is denoted instead of the retractor), a buckle, a tongue, an anchor and so on. The ELR winds the webbing by a spring force and locks the webbing from withdrawing only at a crash so as to restrain the occupant. The buckle is mounted to a suitable position so that the webbing fits the occupant's body well.

Conventionally, the seat belt apparatus locks the webbing from withdrawing by the function of ELR at a crash to restrain the occupant from forward movement.

For improvement in the efficiency of restraining the occupant, each of U.S. Pat. Nos. a for clarifying Components simplythe description will now be made as regard to details of the fitting structure between the inflatable portion 25 and the tongue 3 provided with the gas inlet, and to a structure of a bag filter will now be described.

FIG. 13 (a) is a longitudinal sectional view showing an arrangement of the inflatable portion fixed to the tongue 3. An end 25a of the inflatable portion 25 is fixed to cover an end fitting 31 made of metal which has a flat square section. Furthermore, the end 25a of the inflatable portion is fixed firmly by a caulking fitting 32 so as to cover the periphery thereof so that the inflatable portion 25 is not easily broken away from the end fitting 31.

The end fitting 31 has a tongue pipe 33 secured to the distal end thereof. The tongue pipe 33 enters and engages to the buckle body of the buckle 4(not shown). The tongue pipe 33 has the gas path 34 formed inside thereof. The gas from an inflator (not shown) is introduced into the inflatable portion 25 through the gas path 34 and the inside of the end fitting 31.

The tongue 3 of this embodiment is integrally structured by a combination of the end fitting 31, the caulking fitting 32, and the tongue pipe 33.

The tongue pipe 33 has a lap belt anchor plate 8 fixed to the bottom part thereof to secure an end 7a of a lap belt 7 constituted of a normal webbing.

As shown in this figure, each member (the inner belt 21, the bag filter 26, the tube 22, the knitted textile member 23, the cover 20) of the inflatable portion 25 is overlapped to the peripheral portion of the end fitting 31 coated by a rubber coating 31a to tightly touch with each other. The caulking fitting 32 having an inside coated by a rubber coating 32a is fixed to the peripheral portion of the inflatable portion.

Since the inflatable portion 25 is structured as described above, the inflatable portion 25 is maintained sealingly to form a seal at the end 25a thereof and a break off or a breakage of the end fitting 31 is not possible even if the reaction gas having high pressure is rapidly introduced into the inflatable portion 25.

The structure of the bag filter 26 will be described now in detail.

The bag filter 26 is a filter formed of a fabric having high air permeability which is sewn in an envelope form, and which has substantially the same width as the width of the inner belt 21 and is choked at a distal end side thereof. The bag filter 26 is inserted into the tube 22 and has an end fixed to the tongue 3. Furthermore, a skirt 27 is inserted into the bag filter and has a length which is one third of the length of the bag filter 26. The skirt 27 is cylindrical to have an opening at a distal end thereof and is formed of the same fabric as the bag filter in this embodiment.

The bag filter 26 and skirt 27 are made from heat-resistant fiber in this embodiment. For example, the heat-resistant fiber may be aramid fiber. The aramid fiber is well known as a trade mark Kevlar® fiber and has high stiffness and high elasticity. Further, the aramid fiber has good heat resistance and good flametightness and starts carbonizing at approximately 500°C, so that the aramid fiber does not self-melt and self burn even at a high temperature.

Though the Kevlar® fiber employed in this embodiment is para-bond aramid fiber, meter-bond aramid fiber may, of course, be employed in view of its heat resistance. Furthermore, the filter may be formed of not only textile fabric but also non-woven fabric.

The bag filter 26 is inflated with the gas spouted from the inflator and is capable of collecting the cinder having predetermined or bigger sizes to the inside thereof because of its air permeability. The tube is then inflated with the gas passed through the bag filter 26. At this stage, as the gas temperature is lowered, the bag filter effectively acts as a filter and a diffuser.

The skirt 27 is overlapped around the tongue to effectively display its heat resistance with reference to the temperature distribution as shown in FIG. 2.

The bag filter 26 may be a single by the fabric having different thicknesses at the tongue side and at the end thereof, respectively, or providing may have a metal coating applied to the inside of the bag filter 26 at the tongue side.

Though the aramid fiber is employed in this embodiment as described above, the fiber may be carbon fiber, silicon-carbide fiber or glass fiber each of which has high heat resistance.

The carbon fiber has an extremely high heat resistance because it is made by burning and carbonizing organic fiber. Therefore, the heat resistance of the carbon fiber is expected to withstand approximately 2000°C if the carbon fiber is employed as a diffuser which receives no load as described in the present invention.

The alumina fiber as an oxide inorganic material has also very high heat resistance and is convenient as a textile.

FIG. 13 (b) is a sectional view showing a treatment structure of an end between the inflatable portion 25 and the webbing 10, i.e. the inner belt 21, near a slip guide side.

As the structure is now be described again, the end of the knitted textile member 23 of tubular knitting is integrally glued to the end 20d of the cover 20 by the adhesive and is firmly sewn to the webbing 10. The end 22a of the tube 22 made of silicone rubber is heat-sealed or glued to the inner belt 21 within the knitted textile member 23 inside of the sewing part. The end of bag filter 26 described above extends inside the tube 22.

In FIG. 13 (b), the inner belt in the tube 22 may be cut at the end 22a. Only the cylindrical bag filter 26 having the same functions as described above is accommodated in the tube 22.

In this embodiment, the inflatable portion 25 works as a "webbing" to a light crash or the like, by which the gas generating means does not work. The inflatable portion 25 elongates little in the longitudinal direction because of the elongating characteristic of the knitted textile member 23. Therefore, the inflatable portion 25 can receive a tensile force of the belt as the webbing 10 so as to restrain the occupant properly.

The inflatable portion 25 is inflated in a proper shape as in the embodiment shown in FIG. 13 (a) and FIG. 13 (b) at a crash so as to restrain and ensure the occupant with the wider area of the inflatable portion 25.

Claims

1. An inflatable seat belt apparatus for restraining movement of an occupant in a vehicle, comprising:

a webbing attached to the vehicle and extending for restraining movement of the occupant;

an inflatable portion having an elongated shape and being formed over at least a part of the webbing, said inflatable portion contacting the occupant when the webbing is worn and having an elastic inflatable tube;

a tongue fixed to the elastic inflatable tube and having a gas flow path therein;

a buckle attached to the vehicle and engagable to the tongue, said buckle including a gas path having one end engagable to the gas flow path of the tongue;

first gas generating means connected to the gas path of the buckle, said first gas generating means providing a gas to the elastic inflatable tube to fully inflate the elastic inflatable tube when the vehicle receives a predetermined deceleration;

second gas generating means attached to the gas path of the buckle, said second gas generating means providing a gas for a leak test to the elastic inflatable tube at a pressure less than that supplied by the first gas generating means when the tongue is engaged with the buckle; and

gas leak detecting means disposed adjacent to the gas path of the buckle, said gas leak detecting means checking leakage of the gas in the elastic inflatable tube when the gas from the second gas generating means is supplied to the elastic inflatable tube so that the leakage of the elastic inflatable tube is inspected.

2. An inflatable seat belt apparatus according to claim 1, wherein said gas leak detecting means is a pressure sensor to detect change of the pressure in the elastic inflatable tube.

3. An inflatable seat belt apparatus according to claim 2, wherein said buckle further includes a valve attached to the gas path for switching connection of the gas path, said valve allowing the gas path to communicate the second gas generating means at the leak test and to communicate the first gas generating means after the leak test so that the elastic inflatable tube can be fully inflated by the first gas generating means when the vehicle receives the predetermined deceleration.

4. An inflatable seat belt apparatus according to claim 3, wherein said buckle further includes a gas exhaust pipe connected to the valve so that the gas in the elastic inflatable tube supplied from the second gas generating means is exhausted, after the leak test, from the gas exhaust pipe through the valve.

5. An inflatable seat belt apparatus according to claim 4, wherein said buckle further includes a tongue connection detecting sensor to detect connection between the tongue and the buckle.

6. An inflatable seat belt apparatus according to claim 3, further comprising controlling means connected to the gas leak detecting means, said controlling means preventing the first gas generating means from operating when the gas leak detecting means detects leakage of the elastic inflatable tube.

7. An inflatable seat belt apparatus according to claim 6, further comprising indicating means connected to the gas leak detecting means for indicating a detection result of the gas leak detecting means.

8. An inflatable seat belt apparatus according to claim 1, wherein said inflatable portion further includes a filter attached to the tongue and situated inside the elastic inflatable tube, and a knitted member in a flat form and connected to the webbing to cover the entire inflatable tube, said knitted member having an elasticity in a direction perpendicular to a longitudinal direction of the webbing.

9. An inflatable seat belt apparatus according to claim 8, wherein said inflatable portion further includes a non-expandable cover for covering the knitted member, said cover being sewn by first and second threads along the longitudinal direction of the webbing, said first threads being stronger than the second threads so that when the elastic inflatable tube is inflated, the second threads are torn to allow the elastic inflatable tube to inflate at a portion covered by the second threads.

10. An inflatable occupant protection device comprising:

an elongated webbing;

an inflatable member;

a fabric member connected to the elongated webbing to cover the inflatable member;

a tongue fixed to the inflatable member and having a gas flow path therein;

a buckle engageable with the tongue and having a gas flow path engageable with the gas flow path of the tongue;

a gas source connected to the gas flow path of the buckle to supply gas for inflation of the inflatable member; and

a leak detection control unit connected to the gas flow path of the buckle, the leak detection control unit detecting gas leakage upon engagement of the buckle and tongue;

wherein the fabric member is expandable in a direction transverse to a longitudinal direction of the elongated webbing upon inflation of the inflatable member, thereby pretensioning the elongated webbing.

11. An inflatable occupant protection device according to claim 10, further comprising a filter attached to the tongue. 12. An inflatable occupant protection device according to claim 10, wherein the inflatable member is formed of a heat resisting material. 13. An inflatable occupant protection device according to claim 10, wherein the fabric member is a knitted fabric member that is easily expandable in the direction transverse to the longitudinal

direction of the elongated webbing. 14. An inflatable occupant protection device according to claim 10, wherein the leak detection control unit detects gas leakage with a sensor that detects a change in pressure of the inflatable member while the tongue and the

buckle are engaged. 15. A method for providing occupant protection comprising the steps of:

attaching an elongated webbing to a vehicle;

fixing to the elongated webbing an inflatable member, the inflatable member being covered by a fabric member which is connected to the elongated webbing, the fabric member pre-tensioning the elongated webbing upon inflation of the inflatable member by expanding in a direction transverse to a longitudinal direction of the elongated webbing;

fixing a tongue to the inflatable member, the tongue having a gas flow path therein;

providing a buckle engageable with the tongue and having a gas flow path engageable with the gas flow path of the tongue;

connecting a gas source to the gas flow path of the buckle to supply gas for inflation of the inflatable member; and

connecting a leak detection control unit to the gas flow path of the buckle, the leak detection control unit detecting gas leakage upon

engagement of the buckle and tongue. 16. A method for providing occupant protection according to claim 15, further comprising

the step of attaching a filter to the tongue. 17. A method for providing occupant protection according to claim 15, wherein the step of fixing to the elongated webbing an inflatable member comprises fixing to the elongated webbing an inflatable member formed of a heat resisting material. 18. A method for providing occupant protection according to claim 15, wherein the step of fixing to the elongated webbing an inflatable member comprises fixing to the elongated webbing an inflatable member that is covered by a knitted fabric member that is easily expandable in the direction transverse to the longitudinal direction of the elongated webbing. 19. A method for providing occupant protection according to claim 15, wherein the leak detection control unit includes a sensor, and the method further comprises the step of detecting gas with the sensor, thereby detecting a change in pressure of the inflatable member while the tongue and the buckle are engaged.