EP1117567A4

EP1117567A4 - Inflatable tubular seat restraint system

Info

Publication number: EP1117567A4
Application number: EP98957322A
Authority: EP
Inventors: Gershon Yaniv; David J Romeo; Gregory B Grace; Nathan R Butters; Marvin K Richards
Original assignee: Simula Inc
Current assignee: BAE Systems Simula Inc
Priority date: 1998-10-09
Filing date: 1998-10-09
Publication date: 2003-09-17
Also published as: JP2002527282A; IL141327A0; CA2341509A1; EP1117567A1; WO2000021798A1; AU1360699A; KR20010106490A

Abstract

A seat restraint system (110) whose torso belt (101t) includes an inflatable structure (101) that inflates upon impact to protect the occupants of a vehicle such as an automobile. The inflatable structure is linked to a gas generator (122) and crash sensor. When an impact above a predetermined level of severity is detected, the gas generator is ignited, inflating the inflatable structure which contracts in length as it inflates. In a preferred embodiment, the inflatable structure is a braided tube. As the braided tube inflates, the diameter of the tube increases significantly and its length decreases significantly, due to the orientation of the fibers comprising the braided tube. The contraction in length pretensions the seat belt system by pulling any slack out of the seat belts system.

Description

INFLATABLE TUBULAR SEAT RESTRAINT SYSTEM

This application is a continuation-in-part application of U.S.

Application Serial No. 08/829,750, filed March 31, 1997 (the '750

application), and claims priority from the '750 application, which is

incorporated herein by reference.

BACKGROUND

Field of the Invention.

This invention relates to a system for restraining the body of an

occupant in a vehicle to reduce the extent and severity of injuries during a

crash. More specifically, the invention relates to a seat belt restraint system

which incorporates an inflatable tubular section in the torso section of the

belt. The inflatable tubular section can be made of a woven or braided tube

of continuous high-strength fibers or can alternatively be made from an

extruded net or from a woven net. The restraint system reduces the extent

and severity of both primary and secondary injuries to vehicle occupants.

Background of the Invention.

Conventional seat belts are designed to protect the occupants of

vehicles such as automobiles, trucks, vans, airplanes and helicopters from

primary injuries during an accident. Primary injuries are injuries caused by

the initial impact of the occupants against the interior of the vehicle.

However, the protection provided by conventional seat belts against primary

injuries may sometimes be inadequate. For example, slack in the seat belts may lead to unnecessarily serious primary injuries. In side impacts

conventional belts do not provide occupant head protection on the struck

side of the vehicle. Moreover, the seat belts themselves may often be

responsible for secondary injuries, since the load from the seat belts is

distributed only over small areas of the occupant's body. However, some

prior art belts have tried to lessen primary injuries by incorporating an

inflating mechanism into the seat belt restraint.

For example, U.S. Patent No. 5,282,648, which is incorporated by

reference herein, discloses an inflatable body and head restraint system,

wherein inflatable bladders are attached to the shoulder straps of a harness

restraint. The bladders are stowed partially underneath and partially on

top of harness straps. This configuration provides stability and prevents the

bladders from rolling out of position during inflation. During a crash, the

bladders inflate to protect the upper body, primarily the head and neck of

the occupant.

Additionally, U.S. Patent Nos. 3,948,541 and 3,905,615 to Schulman

disclose another inflatable body and head restraint system, wherein a

bladder is securely affixed to shoulder straps and a lap belt. The bladder

has chin, chest, and pelvic bags. Upon impact, the bladder automatically

inflates to cushion the pelvic areas and to prevent forward rotation of the

head. However, upon inflation the bladder tends to roll out from its position under the shoulder straps. Also, because the bladders are constricted by the

harness, portions of the bladder are subjected to high pressures, which can

lead to splitting of the bladder.

Simple inflatable body restraints are also disclosed in U.S. Patent

Nos. 3,682,498 and 4,348,037 to W. Rutzki and B. Law et al, respectively.

These patents disclose inflatable protective devices that are located in or

under the seat harnesses to which they are attached. These inflatable body

restraints are subject to roll-out and seam or web splitting problems.

In yet another prior art seat belt disclosed in, U.S. Patent Nos.

3,841,654 and 3,970,329 both to Lewis, a vehicle seat system which

comprises a seat belt having an inflatable section is shown. When a collision

is detected, the inflatable section is inflated to protect the person wearing

the seat belt.

The prior art inflatable seat belt structures, such as those identified

above, generally use a unitary inflatable section made from a tightly woven

material, such as 420 denier nylon, which is conventional air bag material.

When deployed, the inflatable section will contract in length somewhat

because the inflation pressure causes it to go from a flat, generally 2-

dimensional shape to a 3-dimensional cylindrical shape. However, only the

ends of the inflatable section contract as they fill and assume a

hemispherical shape. This causes only the ends of the inflatable section to shorten, thus shortening the overall length of the inflatable section. The

fibers of the material do not change their orientation: the two sets of fibers

in the material remain roughly perpendicular to each other throughout the

inflation process.

In the case of the typical inflatable seat belt made of conventional air

bag material as described above, the maximum theoretical amount that the

inflatable structure contracts upon inflation, in an unconstrained condition

prior to being loaded by the occupant, is based only on the width of the flat

material. If inflation results in a relatively small cylindrical diameter then

a relatively small contraction, or shortening, of the length of the seat belt

will occur. The calculation for determining the amount of contraction that

will occur with conventional air bag material upon inflation and in an

unconstrained condition is as follows:

Lf - Li = X (1) where:

X is the amount of contraction

Lf is the length of flat, uninflated, material

Li is the length of unconstrained inflated material, and

Li = Lf - (Df - Di) (2)

Di = 2/π (Df) (3)

Lf - Li = Df(l - 2/π) (4) where:

Df is the width (flat diameter) of flat, uninflated, material Di is the diameter of unconstrained inflated material. As seen in equation (4), the length reduction depends solely on the

uninflated width (flat diameter) of the material.

For example, an inflatable structure having a flat diameter of 20 cm

and a flat length of 100 cm has a maximum achievable contraction of 7.3 cm

or roughly 7% in the absence of any load. In an actual application, with the

belt under tension, the contraction would be much less, e.g., about 3%. This

degree of contraction would provide restraint that is only slightly greater,

and, thus, only slightly more protective than a conventional seat belt.

The construction disclosed in U.S. Patent No. 3,888,503 to Hamilton

comprises an inflatable restraining band having a series of sections, some of which are inflatable to a greater degree than others interconnecting them.

In the Hamilton design, contraction occurs upon inflation only at each end of

each section, and because the sections are of variable inflatable size, the

amount of contraction varies along the structure. By not allowing full

expansion of interconnecting portions or sections of the inflatable band more

hemispherical "ends" occur thus the overall band is foreshortened to a

greater extent than otherwise on expansion, which causes greater

tensioning of the band against the occupant restrained.

Hamilton provides greater protection than the conventional inflatable

seat belt in terms of the provision of greater restraint and hence improves upon a conventional inflatable seat belt. However, the restraint that results from Hamilton's patent is still significantly less than the restraint provided

by the present invention.

None of the patents described above provide the important advantage

of the significant contraction which occurs in the present invention as the

inflatable structure expands upon inflation.

SUMMARY OF THE INVENTION

The present invention is a seat restraint system having an inflatable

structure in the torso section of the system, connected to a gas generator and

crash sensor, that shortens greatly as it inflates. The invention is intended

to replace conventional automotive seat belts. It can also be used in other

types of vehicles and moving structures, such as trucks, vans, airplanes,

railroad trains, elevators and helicopters.

The inflatable structure is a key component of the present invention.

The inflatable structure must have the following characteristics: (1) it must

contract in length substantially as it is inflated — the decrease in length of

the inflated portion of the torso belt (measured when the torso belt is not

under tension) must be at least 15%, and should preferably be 20% to 40%;

(2) the area of the cross-section of the structure should increase

substantially as the tube is inflated — the increase should be at least 50 %,

preferably 50% to 100%; (3) it must remain at a relative pressure sufficient

to maintain a tensile force on the torso belt of 100 lbs (at ~ lg torso mass) for at least five seconds, and preferably at least 7 seconds; (4) the reduction in

the length of the structure is the direct result of the inflation of the

structure, which also results in an increase in the cross-sectional area of the

structure. For example, an inflatable structure which is 91 cm long and has

a diameter of 12 cm prior to inflation, reduces its length by about 28 cm and

increases its diameter to 17 cm when the structure is inflated (not under

tension).

In a first preferred embodiment of the present invention, the

inflatable structure is a tubular structure that comprises a braided tube of

continuous high-strength fibers (instead of the conventional material used

for air bags). The fibers of the braided tube of the present invention form

spirals and change their orientation upon inflation. Prior to inflation, the

spirals are stretched-out longitudinally and the tubular restraint has a

relatively small diameter, as shown in Figure 2a. Subsequent to inflation,

the spirals are closer together longitudinally and form a relatively large

tubular diameter, as shown in Figure 2b. That is, upon inflation, the

braided tube significantly increases its diameter and significantly decreases

its length. This contraction occurs because when the tube is inflated, the

fibers seek an orientation that allows a lower resultant stress and hence a

larger volume within the tube. In order to provide superior gas retention,

braided tube 221 preferably contains an inner bladder 222, as shown in

Figure 2c. In the uninflated state, the braided tube in combination with the

conventional seat belt assumes a flat woven belt configuration and acts as a

conventional seat belt system and holds the occupant in the seat. However,

as the braided tube inflates, the decreasing tube length acts as a

pretensioning device first by drawing any slack out of the seat belt system

and second by pre-loading the occupant. The shortened length of the

braided tube helps greatly to further restrict subsequent occupant motion.

The inflated braided tube additionally provides a much larger

restraint surface area for the occupant's body, which helps to distribute belt

load forces. When the inflated braided tube is loaded by the occupant's

body, it flattens slightly. This flattening increases the contact area between

the body and the braided tube, thus further reducing the stress or load

concentration on the occupant. In a side impact the inflated section provides

occupant head protection.

The inflatable braided tube is connected to a gas generator which is in

turn connected to a crash sensor. When the crash sensor detects an impact

above a predetermined threshold, it sends a signal to the gas generator. The

gas generator is ignited, and generating inflating gas that inflates the

braided tube. The gas generator can be integrated within the seat back or

base, in the buckle assembly of the belt, or in the trunk of the vehicle, for

sound damping purposes and/or other practical considerations. In a second preferred embodiment of the present invention, the

inflatable structure comprises an extruded net. An extruded net is likely to

be less expensive to manufacture than a braided tube. It can also be

manufactured with a more open weave than the braided tube, which could

result in greater contraction. Figures 4a and 4b are schematic diagrams of

an extruded net structure before and after inflation, respectively. The

dimensions of Figures 4a and 4b show how, as the extruded net is inflated, it

contracts in length as it expands in diameter. The extruded net differs from

the braid because the intersecting fibers are joined at the intersections.

When the extruded net is inflated, the joints deform such that the

longitudinal angle of intersection of the fibers increases dramatically, as

shown in Figure 4b. The minimum longitudinal angle prior to inflation is

about 5°. Typically, the longitudinal angle prior to inflation is about 10°-

15°. It typically increases upon inflation to 90°-110°. The maximum

longitudinal angle after inflation can be as high as 150°. This results in the

desired inflatable structure, i.e., a structure which contracts substantially in

length as it is inflated and the cross-section increases.

An alternative second preferred embodiment uses a modified extruded

net, in which the intersections of the fibers are strengthened with nodes, as

shown in Figures 5a and 5b. Typical materials that could be used to

fabricate the modified extruded net include nylon and polyester fibers. The tensile strength of the net at the nodes should be equal to the tensile

strength of the fibers.

A third preferred embodiment uses a woven net, as shown in Figures

6a and 6b. The woven net is similar to the extruded net, but the joints are

woven together instead of being joined together. The joints are reoriented as

the inflatable structure is expanded, as shown in Figure 6b. Typical

materials that could be used to fabricate the woven net include nylon,

polyester and aramid fibers.

A fourth preferred embodiment, shown in Figure 2d, uses a protective

sheath 223 fabricated from woven fabric, e.g. nylon or polyester fabric, in

addition to the braided tube and bladder. The sheath has the appearance

and texture of a conventional seat belt.

The present invention may be implemented in the rear seat of an

automobile by routing the inflatable section of the torso belt through a

constraint at the top of the rear seat and down the back of the rear seat,

essentially similar to the front seat installation shown in Figures la-le.

However, in an alternative embodiment of the present invention, the gas

generator is installed behind the rear seat, as, for example, shown in Figure

7a, and the inflatable section of the torso belt extends across the rear shelf of

the vehicle towards the trunk. In the alternative embodiment shown in

Figures 7a-7b, the inflatable section of the torso belt is shown as connected to a hose which is connected to a rigid pipe. The rigid pipe is connected to a

gas generator, such that the pipe can rotate around the gas generator,

without blocking in any way the fluid connection from the gas generator to

the rigid pipe, or from the rigid pipe to the hose. The rigid pipe is biased

towards the horizontal position.

Figures 8a-8c show an embodiment of the present invention for rear

seat installation that is similar to that of Figures 7a-7b, but uses a hose

retractor instead of a rigid pipe. In this embodiment, hose 800 is flexible,

and tension is kept on the inflatable structure through the use of torsion

springs 801 and rollers 802.

Figure 9 is a schematic diagram of another embodiment of the present

invention, for rear seat installation. This embodiment is similar to the

embodiment shown in Figures la-le, but uses the space between the seat

back and the front trunk wall. The hose is bent into a U shape or J shape,

as shown in Figure 9, and held in place by a channel.

The primary object of the present invention is to prevent or reduce the

severity of primary and secondary injuries suffered by a vehicle occupant in

the event of a crash, by pretensioning the restraint system, further

restricting the motion of the occupant's body, by distributing the restraint

forces over a larger surface area, and to provide side impact head protection. Eight crash tests simulating four equivalent frontal and four

equivalent side impacts were conducted to compare the restraining

capability of the present invention to a conventional three-point seat belt,

and to two prior art air belt systems. The first air belt was inflated to a

relative peak inflation pressure of approximately 1 bar, and the second air

belt was inflated to a relative peak inflation pressure of approximately 3

bars. The results of these tests are listed in Table 1. As shown by Table 1,

the first air belt shows essentially no improvement over the conventional

three-point seat belt. The second air belt shows some improvement

compared to a conventional three-point seat belt, i.e., head displacement was

reduced by six inches in the forward crash simulation and by 2.5 inches in

the side impact simulation. Head rotation, a possible indicator of neck

injuries, was also reduced. However, the restraint system manufactured

according to the present invention, inflated to a peak inflated pressure of

approximately 2 bars, produced the greatest improvements in occupant

kinematics: head displacement was reduced by 15.5 inches (from 20.5

inches to 5.0 inches) in the forward direction) and by 8 inches (from 23

inches to 15 inches) in the lateral direction. The superior performance of

the present invention is due to its ability to reduce its overall length to a

greater extent than prior art restraints. Accordingly, it is an object of the present invention to provide a

protective seat belt system that inflates on impact to protect the occupant of

a vehicle.

It is another object of the present invention to provide a protective

apparatus that restricts occupant motion during a crash.

It is another object of the present invention to provide an inflatable

braided tube member that can greatly shorten (by 20% to 40%) as it inflates

to remove slack and pretension the restraint system.

It is another object of the present invention to provide an inflatable

braided tube that distributes crash loads over larger occupant surface area,

thus minimizing pain and potential injury.

It is another object of the present invention to provide an inflatable

braided tube that is not subject to roping, roll-out or seam splitting

problems.

It is another objective of the present invention to provide an inflatable

braided tube that protects the head in side impacts.

These and other objects of the present invention are described in

greater detail in the detailed description and the appended drawings. BRIEF DESCRIPTION OF THE DRAWINGS

Figure la is a schematic diagram of a side view of the present

invention in the uninflated configuration.

Figure lb is a schematic diagram of a side view of the present

invention in the inflated configuration.

Figure lc is a schematic diagram of a front view of the present

invention in the inflated configuration installed with respect to the driver-

side seat of a typical automobile.

Figure ld is a schematic diagram of cut-away rear view of the present

invention in the uninflated configuration installed with respect to the

driver-side seat of a typical automobile.

Figure le is a schematic diagram of a cut-away rear view of the

present invention in the inflated configuration installed with respect to the

driver side seat of a typical automobile.

Figures lf and lg are schematic diagrams of the latch assembly and

the buckle assembly, respectively, showing how the gas generator can be

mounted in the buckle assembly.

Figure lh is an overall schematic diagram showing how the latch and

buckle assemblies of Figures lf and lg, respectively, are used with the torso

and lap belts. Figure 2a is a schematic diagram of the braided tube of the present

invention in the uninflated state.

Figure 2b is a schematic diagram of the braided tube of the present

invention in the inflated state.

Figure 2c is a schematic diagram of a braided tube having an inner

bladder.

Figure 2d is a schematic diagram of a braided tube having an inner

bladder and a protective sheath.

Figure 3a is a schematic diagram showing the relative distance of the

head displacement and the degree of head rotation during equivalent

simulated forward-impact crash tests in which a conventional seat belt, a

first air belt inflated to a relative pressure of 1 bar, a second air belt inflated

to a relative pressure of 3 bars, and the present invention during the tests

summarized in Table 1.

Figure 3b is a schematic diagram showing the relative distance of the

head displacement and the degree of head rotation during equivalent

simulated side-impact crash tests in which a conventional seat belt, a first

air belt inflated to a relative pressure of 1 bar, a second air belt inflated to a

relative pressure of 3 bars, and the present invention during the tests

summarized in Table 1. Figure 4a is a schematic diagram of an extruded net tubular

structure, prior to inflation.

Figure 4b is a schematic diagram of an extruded net tubular

structure, after inflation.

Figure 5a is a schematic diagram of a modified extruded net tubular

structure, prior to inflation.

Figure 5b is a schematic diagram of a modified extruded net tubular

structure, after inflation.

Figure 6a is a schematic diagram of a woven net tubular structure,

prior to inflation.

Figure 6b is a schematic diagram of a woven net tubular structure,

after inflation.

Figures 7a-7b are a schematic diagrams of a rear seat installation of

the present invention (using a rigid pipe), when the passenger is sitting back

in the seat (Figure 7a) and when the passenger is leaning forward (Figure

7b).

Figures 8a-8c are schematic diagrams of a rear seat installation of the

present invention using torsion springs to maintain tension on the inflatable

structure. Figure 9 is a schematic diagram of a rear seat installation of the

present invention, that uses flexible tubing and a channel guide to maintain

tension and to provide for variation in occupant size.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

A preferred embodiment of the invention is shown in the uninflated

and inflated configurations in Figures la through le installed with respect

to a typical driver-side automobile seat 121. A mirror image of the invention

would function equally as well on a passenger-side automobile seat.

As shown in the Figures la-le, the seat belt system 110 of the first

preferred embodiment comprises lap belt 102, shoulder or torso belt 103,

including an inflatable section 101 comprising a torso portion lOlt, buckle

assembly 105, anchor 106, anchored inertial reels 117 and 118, gas

generator 122, and sensor assembly (not shown). As shown in Figure lc, lap

belt 102 and torso belt 103 form one continuous strap which is attached to or

passes through the male portion of buckle assembly 105. Lap belt 102 is

designed to restrict the forward motion of a seated occupant at the pelvis.

The lap belt 102 is connected to anchored inertial reel 117 so that the length

of the lap belt 102 can be adjusted to accommodate a wide range of seated

occupants. Inertial reel 117 pivotally mounts lap belt 102 to the floor or seat

structure on the door-side of seat 121 (as shown in Figure la and lb). The

other end of lap belt 102 ends at the male portion (the tongue) of buckle assembly 105. The male portion (the tongue) may or may not be fixed to the

belt (i.e., the tongue is either a fixed tongue or a sliding tongue, depending

on the particular locating requirements of the inflatable section which is

dependent on the specific application). The female portion of buckle

assembly 105 is attached to buckle strap 107. Buckle strap 107 is pivotally

mounted to an attachment point in the vehicle, such as the base of seat 121,

or a floor structure on the side of seat 121 that is furthest from the door, by

anchor 106. The female and male portions of buckle assembly 105 fasten

together, thus securing seat belt system 110 around the occupant in a

manner similar to that used by conventional three point seat belt systems.

As shown in Figure ld gas generator 122 is preferably mounted inside

the seat back to protect it from impacts and to dampen the noise it produces

when activated. The gas generator could also be located in the seat base

(not shown). Durable tubing 116 provides a fluid path from gas generator

122 to inflatable braided tube 101.

As shown in Figure la, inflatable section 101 extends diagonally from

the occupant's hip to behind and above the occupant's shoulder and is

attached at each end to torso belt 103. The upper end of inflatable section

101 loops through a D-ring 108 that is mounted to the seat 121 as shown or

to the vehicle (e.g., at the roof rail or at the upper B-pillar area (not shown)).

The torso belt 103 then is anchored to the seat 121 or vehicle (not shown) by an inertial retractor 118. As shown in Figure la, torso strap 103 is

preferably routed inside the vehicle seat to inertial retractor 118, which is

mounted in the lower portion of the seat back. As discussed below with

reference to Figure ld, gas generator 122 is preferably mounted inside the

vehicle seat. Thus, in the configuration shown in Figures la and ld, tubing

116 provides direct fluid communication from the gas generator to inflatable

section 101 in the torso of the restraint system. Torso strap 103, buckle

strap 107, and lap belt 102 are formed from conventional webbing material

such as nylon, dacron, or polyester. Alternatively strap 107 could be a steel

cable.

The key component of the safety belt system 110 is the inflatable

structure 101. In the embodiment illustrated in Figures la-le, the

inflatable structure is a braided tube 101 that is integrated in the torso belt

103. The braided tube 101 is similar to the braided tubes disclosed in U.S.

Patents Nos. 5,322,322 and 5,480,181, which are incorporated by reference

herein.

Figures lf and lg are schematic diagrams of the latch assembly and

the buckle assembly used with an alternative placement for the gas

generator. The generator is placed in the buckle assembly of the torso belt.

Figure lf is a schematic diagram of the latch assembly of the seat belt,

showing lap belt 140, torso belt 141 (which contains the inflatable structure), fill hose 142 and female fill tube 143. A frangible seal 144 at the

entrance to the fill tube protects the inflatable structure from

contamination. The entrance to female fill tube 143 on the latch assembly

in Figure lf mates with male fill tube 145 in the buckle assembly shown in

Figure lg. Fill tube 145 is protected from contamination by frangible seal

146. If the gas generator is ignited, the pressure of the inflating gas bursts

frangible seals 144 and 146, allowing gas to flow from gas generator 150

through the buckle and latch assembly to the inflatable structure in torso

belt 141. Engaging the latch assembly with the buckle assembly seals fill

tubes 143 and 145. Lock tang 149 (at the end of the latch assembly) engages

lock dog 148 (in the buck assembly) in the same manner as conventional

seat belt latch and buckle assemblies, so that the latch assembly locks to the

buckle assembly. Figure lh is an overall schematic diagram of this

embodiment showing torso belt 141, lap belt 152, latch assembly 160, buckle

assembly 161 and lap belt retractor 162.

Braided tube 101 is shown in detail in Figures 2a-2d. Braided tube

101 is comprised of a braided tube of continuous high-strength fibers.

Typical fiber materials include aramid, nylon, dacron, polyamide and

polyester fibers. Braided tube 101 is made of continuous fibers that may or

may not be impregnated with elastomeric material, such as silicone rubber

or urethane. Unlike the conventional fibers employed in prior art for

making air bags, the fibers of this invention form spirals and change their orientation (included longitudinal angles) upon inflation. Prior to inflation,

the spirals are stretched-out longitudinally and the tubular restraint has a

relatively small diameter. Subsequent to inflation, the spirals are closer

together longitudinally and form a relatively large tubular diameter. That

is, upon inflation, the entire braided tube increases its diameter and

decreases its length, or contracts. This contraction occurs because as the

tube is inflated, the fibers seek an orientation that allows a larger volume

within the tube.

As shown in Fig. 2a, angle 201 is a longitudinal angle and angle 202

is a circumferential angle. In the uninflated state, shown in Figure 2a,

braided tube 101 is elongated with its woven fibers forming obtuse and

acute angles at the fiber crossing points 111. For the sake of convenience

and clarity, the angles which are acute in Figure 2a (which would be

bisected by a line parallel to the longitudinal axis of the braided tube) will

be termed the longitudinal angles. The angles which are obtuse in Figure

2a (which would be bisected by a line parallel to the circumference of the

braided tube) will be termed the circumferential angles.

When the braided tube is in the uninflated state, its fibers are at a

longitudinal angle in the range of about 30° to about 70°. In every case,

upon inflation, the fibers will seek a preferred maximum longitudinal angle

of about 110° when the tube is in an unconstrained state. Typically, the angle after inflation is approximately 100° in an unloaded, or unconstrained,

braided tube. Given the range of angles from about 30° to about 70° in an uninflated tube and an angle of about 100° in an unloaded inflated tube, the

range of typical length decrease, or contraction, of the inflatable tube is

about 21.5% (for the 70° to 100° change) to about 33.5% (for the 30° to 100°

change). The percentage of contraction is not a function of the initial

diameter or length of the inflatable tube.

The calculation for determining the amount of contraction that will

occur with the present invention upon inflation and in an unconstrained

condition is as follows:

Lf - Li = X (5) where:

X is the amount of contraction

Lf is the length of flat, uninflated, material, and

Li is the length of unconstrained inflated material and

Li/Lf = cos (θi/2)/cos (θf/2) (6)

Lf - Li = Lf(l - cos (θi 2)/cos (θf/2)) (7) where: θf is the longitudinal angle prior to inflation θi is the longitudinal angle after inflation.

Merely by way of example, an embodiment of the present invention

having an uninflatable flat length of 100 cm and a flat diameter of 20 cm

and constructed with fibers that cross each other at a 36° angle would decrease in length, or contract, to 67 cm or by approximately 33% upon

inflation in an unconstrained condition. (The calculation assumes that the

angle of the fibers in an unconstrained inflated braided tube will be 100°.)

As stated above, the invention contracts as a result of both inflation

and construction. Therefore, it will typically contract about 21.5% to about

33.5% as a result of the change in orientation of the fibers (construction) plus an additional percent (Lf - Li = Df(l - 2/π)) as a result of the geometrical

change from a flat belt to a cylindrical belt with hemispherical ends. Thus

the braid contraction is in addition to — not instead of — the retraction in a

conventional seat belt.

The fibers in the braided tube form clockwise and counterclockwise

spirals both prior to inflation and subsequent to inflation. Prior to inflation,

the spirals are stretched-out longitudinally, and have a relatively small

diameter. Subsequent to inflation, the spirals are closer together

longitudinally, and have a relatively large diameter. This occurs because, as

the tube is inflated, the tube fibers seek an orientation that allows a larger

volume within the tube, and results in lower resultant stress, with fibers

aligned to roughly parallel to the orientation of the resultant stress.

Figure 2b shows that as it inflates, braided tube 101 shortens in

length, while its diameter increases. The braid fibers ultimately seek an

orientation in which the longitudinal angles increase substantially as the tube diameter increases. As the tube diameter increases, the tube length

decreases. If the tube were unconstrained and the longitudinal angles of the

tube were in the range of about 30° to about 70°, the typical range for

unconstrained decrease of the tube length is about 20% to about 39%,

preferably about 21.5% to about 33.5%, and most preferably about 33.5%.

The fibers in the uninflated braided tube typically have a longitudinal

angle in the range of about 30° to about 70°. Upon inflation the longitudinal

angle between the fibers will reach approximately 100°. The preferred

maximum longitudinal inflation angle of the fibers is approximately 110°.

Figure la shows seat belt system 110 of the present invention in the

uninflated state in which braided tube 101 assumes a flat woven belt

configuration and the system acts as part of a conventional 3-point restraint.

The uninflated braided tube in combination with the conventional webbing

forms a high-strength belt that has the same width (approximately 2 inches)

as the conventional webbing material of lap belt 102 and torso belt 103.

As best shown in Figure ld, when a collision occurs, the crash sensor

sends a signal to the initiator in gas generator 122. The initiator then

ignites the gas generator 122, thus producing a gas that passes through

durable tubing 116 and inflates braided tube 101. As gas flows into the

chamber of braided tube 101, the internal pressure causes the tube diameter

to increase and the tube length to decrease. However, the seat belt system 110 is constrained on the outboard side by the first inertial reel 117 and on

the inboard side by anchor 106, and behind the shoulder by the second

(shoulder or torso belt) inertial reel 118. Inertial reels 117 and 118 lock up

during impact, preventing payout of the belt. Thus as braided tube 101

contracts, it pulls any slack out of seat belt system 110. The occupant is

thus provided with a pretensioned seat belt, which restricts the forward

motion of the occupant and reduces primary injuries.

Further, the male portion of the buckle assembly 105 can be located

on the lap belt 102 using rip-stitching or a locating snap or button. When a

collision occurs and upon inflation, the locating attachment between lap belt

102 and buckle 105 releases, allowing the lap portion to pull tight, thereby

further restricting the motion of the occupant and preventing the occupant

from sliding under the lap belt (i.e., submarining).

Braided tube 101 is not stowed under any belt member, but is instead

stowed on the outside of the torso belt. This positioning allows the tube to

inflate evenly without experiencing roll-out problems. Seam splitting

problems common to inflating bladders are also avoided because braided

tube 101 is a seamless structure.

When fully inflated, braided tube 101 has a diameter of

approximately 12 to 18 cm and a relative internal pressure of approximately

1 to 4 bars (2 to 5 bars absolute pressure). Due to increased friction, as the area of contact of inflated braided tube 101 with the occupant increases,

inflated braided tube 101 helps to further restrict occupant motion. Unlike

conventional 3-point seat belt systems, the present invention additionally

helps lessen or prevent secondary belt-inflicted injuries by providing a

substantially larger restraint surface area for the occupant's body, which

helps to distribute belt load forces.

Additionally, the present invention provides side impact crash

protection from head injury by restricting head movement, preventing the

occupant's head from striking the window, the side of the vehicle, or any

intruding objects.

Figures 3a and 3b illustrate the results of simulated crash tests.

These figures demonstrate that the present invention is more effective in

limiting forward and side head displacement in frontal and side impacts,

respectively, than are conventional prior art three-point seat belts and air

belts fabricated from conventional materials.

The crash tests also demonstrated an important feature of the present

invention: the belt continues to contract and further restrains the occupant

after the initial loading. The sequence is as follows:

(1) An impact occurs, causing the vehicle to decelerate suddenly;

(2) The crash sensor detects the impact, and initiates inflation of

the inflatable portion of the torso belt; (3) The occupant continues to move forward (relative to the

vehicle) against the torso belt;

(4) The inflatable portion of the torso belt inflates, pretensioning

the torso belt, distributing the stresses over a wider area, and preventing

the occupant from hitting the windshield;

(5) The occupant reaches his/her maximum forward position — at

this point, the occupant is exerting considerable force on the torso belt,

which puts the torso belt under an additional tensile force, which in turn

prevents the inflatable portion of the torso belt from reaching its maximum

contraction;

(6) The occupant then rebounds back towards the seat back,

relieving the additional tensile force from the torso belt, allowing the

inflatable portion to contract further in length while its diameter expands,

effectively performing a second pretensioning function;

(7) The additional contraction in length keeps the occupant firmly

in the seat during secondary collisions or rollovers, and prevents the

occupant from sustaining further injuries.

Thus the present invention functions quite differently from other

restraint systems, because (unlike a conventional belt pretensioner) the

torso belt continually tries to contract after the initial loading (of the

occupant on the restraint system). In the second preferred embodiment of the present invention, an

extruded net formed in a tubular shape is used as the inflatable structure

(instead of the braided tube). Figures 4a and 4b show the extruded net,

prior to inflation (Figure 4a) and subsequent to inflation (Figure 4b).

Figures 4a and 4b show how the extruded net contracts in length as it is

inflated and expands in diameter. Figures 4a and 4b also show that the

intersecting members 401 form flexible joints 402 at the intersections of the

members, which deform as the tube is inflated and expands. The

longitudinal angle of intersection 403 of the fibers increases dramatically, as

shown in Figure 4b which, just as in the braided tube, causes the tube to

contract substantially in length as its diameter increases. Materials that

could be used to fabricate the extruded net include nylon and polyester.

An alternative second preferred embodiment of the present invention

uses a modified extruded net, in which the intersections of the fibers are

strengthened with nodes, as shown in Figures 5a and 5b. Like the extruded

net shown in Figures 4a and 4b, this embodiment uses members 501 which

are joined at intersections 502. When the tube is inflated, the longitudinal

angle 503 of the intersecting members increases dramatically. Unlike the

extruded net of Figures 4a and 4b, the intersections 502 include nodes 504

which serve to strengthen the net. Typical materials that could be used to

fabricate the modified extruded net include nylon and polyester fibers.

Extruded Net can be obtained from Paeon, Inc., City of Baldwin Park, California 91706, or from Polynet, Inc., P.O. Box 27, Three Rivers,

Massachussetts 01080.

A third preferred embodiment used a woven net, as shown in Figures

6a and 6b. Figures 6a and 6b show fibers 601 woven in a net comprising

intersections 602. The woven net is similar to the extruded net, but the

joints are woven together instead of being joined together. As the tube is

expanded, the joints are reoriented and the longitudinal angle 603 increases,

as shown in Figure 6b. Typical materials that could be used to fabricate the

woven net include nylon, polyester and aramid fibers.

The gas generator 122 used in the invention is preferably similar to

those currently used in automotive side-impact as opposed to frontal air

bags. This is due to the relatively smaller volume and faster filling

requirements of side-impact air bags as opposed to frontal air bags. Gas

generators preferred for this invention must inflate braided tube 101 to a

relative pressure of approximately 1.5 bars (2.5 bars absolute) within 10 to

15 milliseconds.

The present invention could be installed for the protection of

passengers sitting in the rear seat of an automobile using the same

installation as for front seat occupants (e.g., a driver and a passenger), i.e.,

by routing the inflatable portion of the torso section over the top of the back

of the seat. However, the inflatable portion could also be routed through a constraint at the top of the back of the rear seat, over the rear shelf of the

vehicle, and into the trunk, as shown in Figures 7a-7b, 8a-8c and 9. The

retractor winds up the belt when no one is using the restraint system, and

pays out the torso belt to accommodate an occupant. The retractor uses an

inertial reel, i.e., a reel that locks up in the event of a frontal impact. In the

embodiment shown in Figures 7a-7b, the inflatable section of the torso belt

is connected to a hose, which in turn is attached to a rigid pipe. The rigid

pipe is rotatably attached to the gas generator, such that when the gas

generator is ignited and generates inflating gas, the inflating gas goes into

the rigid pipe, through the hose and into the inflatable section of the torso

belt, inflating the inflatable section of the torso belt.

Figures 8a-8c illustrate an alternative to the embodiment shown in

Figures 7a-7b. The embodiment of Figures 8a-8c uses a flexible hose, and a

flexible retractor to maintain tension of the inflatable structure. The

flexible retractor includes torsion springs 801 and rollers 802 to hold flexible

hose 800 under tension.

Figure 9 is a schematic diagram of another embodiment of the present

invention for rear seat installation similar to that of Figures la-le. In this

embodiment, fill hose 901 is held in a low-friction channel 902. Fill hose 901

is connected at one end to gas generator 907 and at its opposite end to

inflatable structure 904 via connector 905. Fill hose 901 is bent into a U shape or J shape, as shown in Figure 9, and held in place by channel 902.

Retractor 906 reels in or pays out the belt as the occupant sits back or moves

forward in her seat. Figure 9 shows the position of the hose and inflatable

structure when the occupant is sitting back in her seat. When the occupant

is in a forward position, the "J" shape shown in Figure 9 becomes much

greater (and looks more like a "U") as the end of inflatable structure 904 and

connector 905 move up the channel to accommodate the forward position of

the occupant. The hose material itself (e.g., nylon) is resilient such that the

"J" or "U" shape is maintained as the belt is payed out or reeled in. Figure 9

also shows D-ring 903 that positions the inflatable structure over the

shoulder of the occupant. Graphite powder or other lubricants may be used,

if necessary to minimize friction between the hose and the channel.

The foregoing disclosure of embodiments of the present invention has

been presented for purposes of illustration and description. It is not

intended to be exhaustive or to limit the invention to the precise forms

disclosed. Many variations and modifications of the embodiments described

herein will be obvious to one of ordinary skill in the art in light of the above

disclosure. The scope of the invention is to be defined only by the claims

appended hereto, and by their equivalents. TABLE I - OCCUPANT RESTRAINT TEST RESULTS

Claims

WHAT WE CLAIM IS:

1. A seat restraint system for a vehicle seat in a vehicle comprising:

(a) a torso belt comprising an inflatable structure that contracts

substantially in length and increases substantially in cross-sectional area

when it is fully inflated, wherein the inflatable structure assumes a flat

configuration prior to inflation;

(b) a gas generator fluidly connected to the inflatable structure;

(c) a crash sensor electrically connected to the gas generator, said

crash sensor initiating generation of gas by the gas generator when an

impact is detected such that the inflatable structure is fully inflated; and

(d) a constraint mounted at the top of the vehicle seat, wherein the

inflatable structure is routed through the constraint such that portions of

the inflatable structure on both sides of the constraint are inflatable, and

such that the inflated portion of the torso belt lying over the top of the

vehicle seat would push an occupant of the seat down into the seat, thus

controlling the position of the occupant during a collision.

2. The seat restraint system of claim 1, wherein the seat is the rear seat

of a passenger vehicle, and wherein the inflatable structure extends across a

rear shelf of the vehicle towards the vehicle's trunk.

3. The seat restraint system of claim 2, wherein the gas generator is installed in the vehicle's trunk.

4. The seat restraint system of claim 3, wherein the inflatable structure

is fluidly connected to a rigid pipe which in turn is fluidly connected to the

gas generator, and wherein the system is configured such that the rigid pipe

would rotate up when an occupant leans forward and would rotate back

when the occupant sits back in the rear seat.

5. The seat restraint system of claim 3, wherein the inflatable structure

is fluidly connected to a hose in a hose retractor, and wherein the hose is in

turn fluidly connected to the gas generator.

6. The seat restraint system of claim 3, further comprising a hose

between the inflatable structure and the gas generator, wherein said hose is

fluidly connected to the gas generator on one end and fluidly connected to

the inflatable structure at its other end, further comprising a low-friction

channel constraining the hose within the channel.

7. The seat restraint system of claim 6, wherein the hose has a gas

generator end, and wherein the gas generator end of the hose is attached to

a belt, further comprising a retractor configured to pay out the belt when an

occupant leans forward and to reel in the belt when the occupant sits back.

8. The seat restraint system of claim 1, wherein the inflatable structure

is a braided tube.

9. The seat restraint system of claim 1, wherein the inflatable structure

is an extruded net.

10. The seat restraint system of claim 9, wherein the extruded net

comprises intersecting fibers joined at intersections forming longitudinal

angles which increase from 5°-15° prior to inflation, to 90° -150° after

inflation, when the inflatable structure is fully inflated without tension.

11. The seat restraint system of claim 10, wherein the longitudinal angles

increase to 90°-110° after inflation.

12. The seat restraint system of claim 1, wherein the inflatable structure

is a woven net.

13. The seat restraint system of claim 1, wherein the inflatable structure

further comprises a protective sheath.

14. The seat restraint system of claim 1, further comprising a lap belt,

wherein the lap belt and the torso belt form one continuous strap.

15. The seat restraint system of claim 14, wherein the continuous strap

passes through a first component of a buckle assembly, further comprising a

buckle strap attached to a second component of the buckle assembly, said

buckle strap being pivotally mounted to the vehicle.

16. The seat restraint system of claim 15, wherein the gas generator is

mounted in the buckle assembly.

17. The seat restraint system of claim 1, wherein the gas generator is

mounted inside the seat back.

18. A seat restraint system for a rear seat in a vehicle comprising:

(a) a belt comprising a torso belt portion and a lap belt portion,

said torso belt portion comprising an inflatable structure that contracts

substantially in length and increases substantially in cross-sectional area

when it is fully inflated, wherein the inflatable structure assumes a flat

configuration prior to inflation;

(b) a gas generator fluidly connected to the inflatable structure;

(c) a crash sensor electrically connected to the gas generator, said

crash sensor initiating generation of gas by the gas generator when an

impact is detected such that the inflatable structure is fully inflated;

(d) a constraint mounted at the top of the vehicle seat, wherein the

inflatable structure is routed through the constraint such that portions of the inflatable structure on both sides of the constraint are inflatable, and

such that the inflated portion of the torso belt lying over the top of the

vehicle seat would push an occupant of the seat down into the seat, thus

controlling the position of the occupant during a collision, and wherein the

inflatable structure extends across the rear shelf of the vehicle into the

trunk of the vehicle;

(e) a buckle assembly, said belt passing through a first component

of the buckle assembly; and

(f) a buckle strap connected to a second component of the buckle

assembly, said buckle strap being pivotally attached to the vehicle,

wherein the lap belt portion of the lap belt is connected to an inertial

reel anchored to the vehicle.

19. The seat restraint system of claim 18, wherein the inflatable

structure is fluidly connected to a rigid pipe which in turn is fluidly

connected to the gas generator, and wherein the system is configured such

that the rigid pipe would rotate up when an occupant leans forward and

would rotate back when the occupant sits back in the rear seat.

20. The seat restraint system of claim 18, wherein the inflatable

structure is fluidly connected to a hose in a hose retractor, and wherein the

hose is in turn fluidly connected to the gas generator.

21. The seat restraint system of claim 18, further comprising a hose

fluidly connected at one end to the inflatable structure and its other end to

the gas generator, further comprising a low-friction channel constraining the

hose within the channel.

22. The seat restraint system of claim 21, wherein the hose has a gas

generator end, and wherein the gas generator end of the hose is attached to

a belt, further comprising a retractor configured to pay out the belt when an

occupant leans forward and to reel in the belt when the occupant sits back.

23. The seat restraint system of claim 18, wherein the inflatable

structure is a braided tube.

24. The seat restraint system of claim 18, wherein the inflatable

structure is an extruded net.

25. The seat restraint system of claim 24, wherein the extruded net

comprises intersecting fibers joined at intersections forming longitudinal

angles which increase from 5°-15° prior to inflation, to 90° -150° after

inflation, when the inflatable structure is fully inflated without tension.

26. The seat restraint system of claim 25, wherein the longitudinal angles

increase to 90°-110° after inflation.

27. The seat restraint system of claim 18, wherein the inflatable

structure is a woven net.

28. The seat restraint system of claim 18, wherein the inflatable

structure is a braided tube within a protective sheath.

29. A seat restraint system for a rear seat in a vehicle comprising:

(a) belt having a lap belt portion, and a torso belt portion, wherein

the lap belt portion is attached to a first inertial reel pivotally attached to

the vehicle, and wherein the belt is attached to a first portion of a buckle

assembly at the end of the lap portion of the belt and at the beginning of the

torso belt portion of the belt;

(b) an inflatable tubular structure comprising part of the torso

belt, said inflatable tubular structure being routed through a constraint over

the top of the vehicle seat towards the trunk of the vehicle;

(c) a gas generator fluidly connected to the inflatable tubular

structure;

(d) a strap attached at one end to a second portion of the buckle

assembly, and anchored to the vehicle at the other end, wherein the inflatable tubular structure increases its cross-sectional

area by at least 50% and reduces its length by at least about 20%, when it is

fully inflated in an unconstrained state, and

wherein the inflatable structure is routed through the constraint such

that portions of the inflatable structure on both sides of the constraint are

inflatable, and such that the inflated portion of the torso belt lying over the

top of the vehicle seat would push an occupant of the seat down into the

seat, thus controlling the position of the occupant during a collision, and

wherein the inflatable tubular structure is not vented after inflation,

such that it reduces the extent and severity of secondary injuries as well as

reducing the extent and severity of primary injuries.

30. The seat restraint system of claim 29, wherein the inflatable

structure is fluidly connected to a rigid pipe which in turn is fluidly

connected to the gas generator, and wherein the system is configured such

that the rigid pipe would rotate up when an occupant leans forward and

would rotate back when the occupant sits back in the rear seat.

31. The seat restraint system of claim 29, wherein the inflatable

structure is fluidly connected to a hose in a hose retractor, and wherein the

hose is in turn fluidly connected to the gas generator.

32. The seat restraint system of claim 29, further comprising a hose

fluidly connected at one end to the inflatable structure and its other end to

the gas generator, further comprising a low-friction channel constraining the

hose within the channel.

33. The seat restraint system of claim 32, wherein the hose has a gas

generator end, and wherein the gas generator end of the hose is attached to

a belt, further comprising a retractor configured to pay out the belt when an

occupant leans forward and to reel in the belt when the occupant sits back.

34. The seat restraint system of claim 29, wherein the inflatable

structure is a braided tube.

35. The seat restraint system of claim 29, wherein the inflatable

structure is an extruded net.

36. The seat restraint system of claim 35, wherein the extruded net

comprises intersecting fibers joined at intersections forming longitudinal

angles which increase from 5°-15° prior to inflation, to 90°-150° after

inflation, when the inflatable structure is fully inflated without tension.

37. The seat restraint system of claim 36, wherein the longitudinal angles

increase to 90°-110° after inflation.

38. The seat restraint system of claim 29, wherein the inflatable

structure is a woven net.

39. The seat restraint system of claim 18, further comprising a protective

sheath enclosing the inflatable structure.

40. A seat restraint system for a rear seat in a vehicle comprising:

(a) belt having a lap belt portion, and a torso belt portion, wherein

the lap belt portion is attached to a first inertial reel having means for

pivotally attaching the first inertial reel to the vehicle, and wherein the belt

is attached to a first portion of a buckle assembly at the end of the lap

portion of the belt and at the beginning of the torso belt portion of the belt;

(b) an inflatable tubular structure comprising part of the torso

belt, said inflatable tubular structure routed through a constraint;

(c) a gas generator fluidly connected to the inflatable tubular

structure;

(d) a strap attached at one end to a second portion of the buckle

assembly;

wherein the inflatable tubular structure increases its cross-sectional

area by at least 50% and reduces its length by at least about 20%, when it is

fully inflated in an unconstrained state, and wherein the inflatable structure is routed through the constraint such

that portions of the inflatable structure on both sides of the constraint are

inflatable, and such that the inflated portion of the torso belt would push an

occupant of a vehicle seat down into the seat, thus controlling the position of

the occupant during a collision, and

wherein the inflatable tubular structure is not vented after inflation,

such that it reduces the extent and severity of secondary injuries as well as

reducing the extent and severity of primary injuries.

41. The system of claim 40, wherein the inflatable structure is a braided

tube.

42. The system of claim 40, wherein the inflatable structure is an

extruded net.

43. The system of claim 40, wherein the inflatable structure is a woven

net.

44. The system of claim 40, further comprising a hose fluidly connected at

one end to the inflatable structure and at its other end to the gas generator.

45. The system of claim 44, wherein the hose is held within a hose

retractor.

46. The system of claim 44, wherein the hose is fluidly connected to the

gas generator through a rigid pipe.

47. The system of claim 44, further comprising means for rotating the

rigid pipe as an occupant of the vehicle move forward and back.

48. The system of claim 44, further comprising a low-friction channel,

wherein the hose is constrained within the channel.

49. The system of claim 40, wherein the buckle assembly comprises a gas

generator.