Inflatable seat belt having bag filter

Abstract

An inflatable seat belt apparatus is formed of an inflatable portion which is usually maintained in a band shape and has an envelope part inflated and deployed in a spindle shape by introducing gas generated by a gas generating device, the gas generating device acting in case of exceeding a predetermined threshold, a webbing having the inflatable portion extending over at least a range directly contacting with an occupant, a tongue fixed to an end of the inflatable portion and having a gas path from the gas generating device and a buckle to which the tongue is detachably engaged. The inflatable portion has an elastic inflatable unit inserted into the envelope part and is inflated and deployed by introducing the gas generated by the gas generating device into the elastic inflatable unit via a filter.

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 structural portion formed in an envelope shape which is usually maintained in a band shape and is inflated, in an accident in a predetermined form to withstand high temperature gas spouted from a gas generating means.

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

Such a seat belt apparatus comprises a webbing as a woven belt made of a fabric which has approximately a 50 mm width and is formed according to Japanese Industrial Standard, a retractor (hereinafter referred to ELR: Emergency Locking Retractor), a buckle, a tongue, an anchor and so on. The ELR winds the webbing by a winding force of a spring and locks the webbing from withdrawing only at a crash so as to restrain the occupant. The buckle is mounted on a suitable position near the floor 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 a forward movement.

For improvement in the efficiency of restraining the occupant, each of U.S. Pat. Nos. for clarifying relationships between details of the fitting structure between the inflatable portion 25 and the tongue 3 provided with the gas inlet, A mechanism of releasing the tongue 3 from the buckle 4 will now be described.

As the press button 50 is pressed in the direction of the arrow C as shown in FIG. 10, a protuberance portion 49a of the release operational ring 49 is pressed by an operational arm 50b mounted on the press button 50 in the direction of the arrow C, so that the release operational ring 49 slides against a biasing force of spring 48 in the direction of the arrow C to release the pressure of the metal ball 47 from the release operational ring 49. Therefore, the metal balls 47 are released from the tubular groove 33b of the tongue pipe 33. As a result, the tongue pipe releasing ring 45 in the buckle body 44 is biased by a spring 46 in a direction of the arrow D to push out the tongue pipe 33 from the inside of the buckle body 44 and then the tongue 3 is released from the buckle 4.

FIGS. 12(a), 12(b) are explanatory drawings showing modified filters 26, 26A.

In the embodiment described before, to improve the heat resistance around the tongue 3 where the temperature of the spouted gas is high, the skirt 27 is mounted inside of the bag filter 26 as shown in FIG. 7. However, touch of the belt and feeling when wearing the belt are bad because the belt has a thick portion by the overlapping structure. The modifications as shown in FIGS. 12(a) and 12(b) are the bag filters structured by only one piece.

For the bag filter 26 shown in FIG. 12(a), a textile having different fabric thickness which is formed of aramid fiber is employed to vary the performance of heat resistance along the longitudinal direction. For a portion around the tongue, a thick fabric 26A which has higher heat resistance is employed in order to lower the temperature of the diffuser. For the head, a sheer fabric 26B which has lower heat resistance is employed to mainly obtain a filter effect. It is possible that different kinds of heat-resistance fibers are combined and sewn. That is, a higher heat-resistance fiber may be used around the tongue and a sheer aramid fiber fabric may be used around head.

FIG. 12(b) illustrates an example that a metal film coating such as aluminum is provided to an inner surface of the bag filter 26 for a range corresponding to the skirt part. Though the coated range has non-air permeability, the thermal insulation effect is improved at the tongue portion. Therefore, the temperature in the tube is equalized and the highest temperature around the tongue is lowered.

The range to be coated is preferably set with reference to the gas flow as shown in FIG. 13.

That is, the shoulder belt, i.e. the tube 22, the inner belt 21 and the bag filter 26, is curved gently around the tongue to fit to the body of the occupant D. In this state, an elbow part 26a of the bag filter 26 is hit directly and intensively by the heat flow when the gas is spouted from the inflator (not shown). Therefore, the temperature of the elbow part 26a is raised partially to quite a high temperature. Since the bag filter is employed not to directly provide radiant heat in this embodiment, it is necessary to deal with such partial and continuous heating. Therefore, preferably, the elbow part 26a is provided with the above described coating or 2 two sheets of textile fabrics are overlapped at this part.

Claims

1. An inflatable seat belt 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 formed over a part of the webbing and contacting the occupant when the webbing is worn, said inflatable portion including a cylindrical skirt disposed on one side of the webbing and formed of a heat resisting material; a filter directly attached to and completely surrounding the skirt; an elastic inflatable tube having an elongated shape and completely surrounding the webbing and the filter containing the skirt, said elastic inflatable tube having heat resistance and being fixed to the webbing; 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;

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

a buckle attached to the vehicle and engagable to the tongue, said buckle having a port body to supply hot gas to the inflatable portion through the gas flow path of the tongue, said hot gas flowing through the skirt and passing through the filter to lower temperature of the hot gas so that the inflatable tube is inflated by the gas while the knitted member is expanded by enlargement of the tube.

2. An inflatable seat belt according to claim 1, wherein said inflatable portion formed of the skirt, the filter, the inflatable tube and the knitted member is a laminated and not folded.

3. An inflatable seat belt according to claim 2, wherein said inflatable portion further includes a non-expandable cover for covering the knitted member, said cover being sewn by a thread along the longitudinal direction of the webbing so that when the inflatable tube is inflated, the thread is torn to allow the inflatable tube to inflate easily.

4. An inflatable seat belt according to claim 3, wherein said skirt has a length of about one third of the length of the filter.

5. An inflatable seat belt according to claim 4, wherein said inflatable portion further includes an end fitting situated inside the skirt and a caulking fitting situated over the cover to sandwich the skirt, the filter, the inflatable tube and the knitted member therebetween, said tongue passing through the end fitting and the caulking fitting.

6. An inflatable seat belt according to claim 5, wherein said elastic inflatable tube is made of silicone rubber.

7. An inflatable occupant protection device comprising:

an elongated webbing;

an inflatable member;

a bag filter disposed within the inflatable member which filters gas flowing into the inflatable member upon inflation thereof; and

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

wherein the fabric member expands in a direction transverse to a longitudinal direction of the elongated webbing upon inflation of the inflatable member, thereby pre-tensioning the elongated webbing.8. An inflatable occupant protection device according to claim 7, wherein the inflatable member includes a skirt disposed within the bag filter.9. An inflatable occupant protection device according to claim 8, wherein the skirt is formed of a heat resisting material.10. An inflatable occupant protection device according to claim 8, 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.11. An inflatable occupant protection device according to claim 7, further comprising a tongue having a gas flow path therein, the tongue being connected to the inflatable member.12. An inflatable occupant protection device according to claim 11, further comprising a buckle for engaging the tongue, the buckle having a body to supply gas to the inflatable member

through the gas flow path of the tongue.13. 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; and

disposing a bag filter within the inflatable member, the bag filter filtering gas flowing into the inflatable member upon inflation of the inflatable member.14. A method for providing occupant protection according to claim 13, further comprising the step of disposing a skirt within the inflatable member.15. A method for providing occupant protection according to claim 14, wherein the step of disposing a skirt within the inflatable member comprises disposing a skirt formed of a heat resisting material within the inflatable member.16. A method for providing occupant protection according to claim 13, further comprising the step of connecting a tongue to the inflatable member, the tongue having a gas flow path therein.17. A method for providing occupant protection according to claim 16, further comprising the step of providing a buckle for engaging the tongue, the buckle having a body to supply gas to the inflatable member through the gas flow path of the

tongue. . A method for providing occupant protection according to claim 13, 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.