Background of the Invention
The present invention relates to a seat belt device for protecting
a vehicle occupant in a vehicle collision, and more particularly to an air belt
device comprising an envelope-like or bag-shaped belt as a part of the seat belt
which is inflated with gas from a gas generator.
One of such air belt devices is described in Japanese Patent Unexamined
Published Application No. H05-85301. Fig 9(a) is a perspective view of an air belt
device of the application and Fig. 9(b) is a sectional view taken along line B-B
of Fig. 9(a).
The air belt device 1 comprises a shoulder belt 2 to be extended at
an angle from the right side to the left side of an occupant, a lap belt 3 to be
extended from the right side to the left side of the occupant, a buckle device 4
disposed at, for example, a vehicle floor, a tongue 5 to be inserted into and engaged
with the buckle device 4 when the occupant wears the belt, and an intermediate guide
6 for guiding the shoulder belt 2.
The shoulder belt 2 comprises a normal belt 2a which is the same as
a typical conventional seat belt, and an envelop-like belt 2b connected to an end
of the normal belt 2b. The normal belt 2a is guided by and freely slides against
the intermediate guide 6. The other end of the normal belt 2a is connected to a
seat belt retractor 7 with an emergency locking mechanism (ELR) which is fixed to
the vehicle body. The normal belt 2a is provided in such a manner as to be wound
into the seat belt retractor 7.
The envelop-like belt 2b is positioned to be in contact with the occupant
and is connected to the tongue 5 at an end opposite to the end connected to the
normal belt 2a.
The lap belt 3 comprises a normal belt which is the same as a typical
seat belt, of which one end is connected to the tongue 5 and the other end is connected
to a seat belt retractor 8 with an emergency locking mechanism (ELR) which is fixed
to the vehicle body. Connected to the buckle device 4 is a gas generator 9 which
acts in case of emergency such as a vehicle collision to generate high-pressure
The tongue 5 and the buckle device 4 are provided with paths for introducing
gas from the gas generator 9 to the envelop-like belt 2b.
The inflatable belt 2b of the shoulder belt 2 has a belt body 2c,
which is formed in an envelope shape, and a cover 2d. As shown by the solid lines
in Figure 11(b), the belt body 2c is folded and covered by the cover 2d. Both ends
of the cover 2d are then connected, by stitching 2e, so that the inflatable belt
2b maintains a band-like shape during normal operation. The stitching 2e of the
cover 2d is easily torn by expansion force of the shoulder belt 2 when the gas generator
9 is actuated so that the inflatable belt 2b is deployed as shown by a two-dot chain
line in Figure 11(b).
Disclosed in Japanese Patent Publication No. S63-39462 is an air belt
device in which an inflatable cushion similar to an air belt is attached to a webbing
of a seat belt device. The inflatable cushion is made of nylon sheets coated with
neoprene rubber. The joint of the nylon sheets is made by suitably stitching in
such a manner as to allow gas leak through the joint. The gas leak can reduce the
impact applied to a vehicle occupant.
In the above structure of reducing the impact by allowing gas leak
through the joint of joint between the sheets as described in S63-39462, there is
a possibilty that the gas leaked through the joint directly hits the vehicle occupant.
The control of the amount of gas leaked through the joint is quite difficult in
practice so that the amount of gas to be leaked can not be controlled to suitably
reduce the impact.
The US-A-3,801,156 discloses a safety belt which comprises at least
one hollow body, at least one member containing expandable gas for blowing up the
hollow body and including closure means as well as a device for releasing the blow-up
in case of an accident. The hollow body has a plurality of exhaust openings for
emergence from the hollow body with in a shortest time period under the effect of
the pressure exerted by the body of the belt user.
From the US-A-3,791,670 (on which the preamble of claim 1 is based)
an air belt device with an inflatable air belt, a gas generator for supplying gas
into said air belt to inflate said air belt and a belt engagement device including
a tongue to which said air belt is connected is known. A buckle, with which said
tongue is engaged, is provided with first and second gas paths and said tongue is
provided with first and second guide paths connecting the inside of said air belt
with said first and second gas paths respectively. Gas is being supplied into said
first gas path from the gas generator.
It is an object of the present invention to provide an air belt device
which, after an air belt is deployed, can discharge gas in a suitable amount toward
a suitable position outside the air belt.
An air belt device of the present invention comprises: an air belt
which is inflatable; a gas generator for supplying gas into the air belt to inflate
the air belt; and a bolt engagement device including a tongue to which the air belt
is connected and a buckle which the tongue is engaged with. The belt engagement
device further includes a gas discharge means which, after the gas generator is
actuated and the air belt is inflated, gradually discharges gas out of the air belt.
The air belt device according to the present invention has the gas
discharging means which, after the gas generator is actuated to inflate the air
belt, gradually discharges gas out of the air belt. Therefore, when an occupant
is pushed strongly by the inflated air belt, the gas within the air belt is gradually
discharged, thereby reducing the impact applied to the occupant.
Since, in the present invention, the belt engagement device composed
of the tongue and the buckle includes the gas discharging means, the discharged
gas is discharged to a lower portion of the cabin of the vehicle so that the gas
never directly hits the occupant.
In the present invention, it is preferable that the buckle is provided
with a first gas path into which gas is upwardly supplied from the gas generator
and through which the gas is jetted out of a spout portion at the top of the buckle,
and a second gas path into which gas from the air belt is downwardly introduced
and through which the gas is discharged out of the buckle downwardly or laterally,
and the tongue is provided with a first guide path connecting the first gas path
and the inside of the air belt, and a second guide path connecting the inside of
the air belt and the second gas path, and that the gas discharging means is composed
of the second guide path and the second gas path. As the gas discharging means is
composed of the second guide path and the second gas path as mentioned above, the
amount of discharge gas can be controlled in a predetermined amount.
In this case, the second gas path is formed to open beneath the buckle
so that the gas discharged from the air belt is discharged beneath the buckle, thereby
securely preventing the gas from directly hitting the occupant.
In the present invention, the tongue and the buckle have seal members
closing. The seal members prevent the ingress of foreign materials (such as dirt
, dust, and sand particles) into the paths.
Fig. 1(a) is a perspective view of a seat on which an air belt device
according to an embodiment is mounted and Fig. 1(b) is a perspective view of the
air belt device.
Figs. 2(a) through 2(e) are structural views of the air belt.
Figs. 3(a) through 3(d) are structural views of the air belt in the
Figs. 4(a) and 4(b) are structural views of a tongue and a buckle
of the air belt device according to the embodiment of the present invention.
Figs. 5(a) through 5(c) are structural views of the buckle.
Figs. 6(a) through 6(d) are structural views of the tongue.
Figs. 7(a) and 7(b) are a front view and a sectional view of the buckle
and the tongue in the engaged state.
Figs. 8(a) through 8(d) are perspective views showing alternatives
of the buckles.
Figs. 9(a) and 9(b) are structural views of a conventional air belt
Figs. 10(a) and 10(b) are structural views of a knit cover.
Figs. 11(a) and 11(b) are structural views of the knit cover.
Hereinafter, embodiments will be described with reference to the drawings.
Fig. 1(a) is a perspective view of a cabin of a vehicle in which an air belt device
according to one embodiment of the invention is mounted and Fig. 1(b) is a perspective
view showing the air belt device. Fig. 2(a) is a plan view showing a portion around
a joint between a shoulder belt and a lap belt, Fig. 2(b) is a plan view of an envelop-like
belt, and Figs. 2(c), (d), (e) are sectional views taken along lines C-C, D-D, and
E-E, respectively. Fig. 3(a) is a plan view of the shoulder belt when the air belt
is in the deployed state, Fig. 3(b) is a plan view of the envelop-like belt in the
deployed state, and Figs. 3(c) and 3(d) are sectional views taken along lines C-C
and D-D, respectively. Fig. 4 through Fig. 7 are explanatory views of a belt engagement
As shown in Fig. 2 and Fig. 3, an air belt 2B comprises an envelop-like
belt 10 and a knit cover 12 made of woven fabric and surrounding the envelop-like
belt 10. The envelop-like belt 10 is formed in such a configuration that a portion
confronting the chest and abdomen of an occupant in a seat has a larger area. The
portion with the larger area is folded to be in a band-like configuration as shown
in Fig. 2(b), 2(c) and 2(d).
The knit cover 12 can be stretched in the width direction, but is
hardly stretched in the longitudinal direction because it is processed by hot-drawing.
The knit cover 12 is subjected to tensile load applied to the air belt 2B. In Fig.
10 and Fig. 11, illustrations at the left hand side show examples of ways of knitting
the knit cover. Fig. 10 shows a normal warp knitting and Fig. 11 shows a warp knitting
in which insert yarns are added to improve the strength and to allow the thickness
to be more thin.
The air belt 2B and the normal shoulder belt 2a are connected by sewing.
The envelop-like belt 10 and the knit cover 12 are both sewn to the normal belt
Once a gas generator is actuated in the state that the tongue is engaged
with the buckle, the air belt 2B is inflated. At this point, the length of the knit
cover 12 in the longitudinal direction of the air belt 2B is reduced so that the
air belt 2B comes in close contact with the occupant, thereby securely protecting
the occupant. In Fig. 10 and Fig. 11, illustrations at the right hand side show
the state that the length of the knit cover 12 is reduced in the longitudinal direction
when the air belt 2B (the envelop-like belt 10) is inflated. As mentioned above,
the knit cover is hardly stretched in the longitudinal direction because it is processed
by hot drawing. The knitted loops of the knit cover 12 are extended in the lateral
direction when the envelop-like belt 10 is inflated. As a result of this, the knit
cover 12 shrinks its length in the longitudinal direction to reduce the length of
the air belt 2B in the longitudinal direction.
Hereinafter, the structure of a tongue and a buckle which can be suitably
employed in the present invention will be described with reference to Figs. 4 through
Figs. 4 through 7 show a first embodiment of a tongue and a buckle.
Fig. 4(a) is a perspective view showing the tongue 14 and the buckle 16, Fig. 4(b)
is an enlarged view of the buckle of Fig. 4(a). Figs. 5(a) through 5(c) show the
structure of the buckle of this embodiment, Figs. 6(a) through 6(d) show the structure
of the tongue, and Figs. 7(a) and 7(b) are a front view and a sectional view showing
the state that the tongue and the buckle are engaged with each other.
As clearly shown in Fig. 6, the tongue 14 comprises a tongue base
18 provided with a first guide path 21 and a second guide path 22 inside thereof,
a tongue plate 24 and an anchor 26 which are connected to the tongue base 18, a
ring 28 for fixing the air belt 2B to the tongue base 18, and a synthetic resin
cover 32 for surrounding the tongue base 18.
The tongue base 18 has a cavity inside thereof. The cavity is divided
into two branches extending toward the ends of the tongue (the side that is inserted
into the buckle) whereby the first guide path 21 and the second guide path 22 are
Each guide path 21, 22 has an opening at the ends of the tongue. The
opening is closed by a seal member 41, 42. The seal member 41, 42 can be opened
when gas pressure is applied, as mentioned later.
The anchor 26 is provided with an opening formed therein. The end
of the lap belt 3 is inserted through the opening and then connected to the anchor
The tongue plate 24 is inserted into a tongue-plate inlet 34 (Figs.
4 and 5) of the buckle 16 such that a latch hole 36 is latched with a latch pawl
of a latch mechanism 38 in the buckle 16. Pressing a press button 40 provided in
the buckle 16 releases the latching. At the same time, the tongue plate 24 is pushed
out of the buckle 16 by a spring.
As clearly shown in Figs. 5(a) through 5(c), the buckle 16 is provided
with a first gas path 51 and a second gas path 52 inside thereof. The first gas
path 51 is connected to an inflator 58 (the gas generator) through a hose 54.
The top (the surface confronting the tongue) of the buckle 16 is provided
with a seal member 61 for closing the first gas path 51 and a seal member 62 for
closing the second gas path 52.
In this embodiment, the outer surface of the buckle 16 is covered
by the synthetic resin cover 64 so that the seal members 61, 62 are formed integrally
with the synthetic resin cover 64. The synthetic resin cover 64 is provided with
tear lines formed in portions thereof above the gas paths 51, 52 so that areas surrounded
by the tear lines become the seal members 61, 62. As the gas pressure is applied,
the synthetic resin cover 64 is torn along the tear lines. As a result of this,
the seal members 61, 62 open just like flaps as shown in Fig. 4(b).
The lower end of the second gas path 52 opens downwardly at the bottom
of the buckle 16 whereby the gas from the second gas path 52 is discharged downwardly.
The buckle 16 and the inflator 58 have brackets 66, 68 for fixing
them to the vehicle body member.
Hereinafter, the operation of the air belt as structured above will
be described. The occupant sits in the seat and engages the tongue 14 with the buckle
16 as shown in Fig. 4(a).
In this state, once the inflator 58 is actuated at a vehicle collision,
the seal member 61 is first opened by gas pressure as shown in Fig. 7(b) and the
seal member 41 is then opened. The gas is supplied through the first guide path
21 in the tougue base 18 to the air belt 2B to inflate the air belt 2B. In this
case, since the gas from the inflator 58 flows upwardly through the first gas path
51 and the first guide path 21, little gas pressure is applied to the seal member
42 so that the seal members 42, 62 are still closed.
When the air belt 2B is inflated, the length of the air belt 2B is
reduced so that the air belt closely fits to the body of the occupant, as mentioned
When the air belt 2B is sufficiently inflated or the occupant is pushed
by the inflated air belt 2B, the pressurized gas filled in the air belt 2B is applied
to the seal member 42 through the second guide path 22 so that the seal member 42
opens downwardly and the seal member 62 then opens downwardly. The gas in the air
belt 2B is gradually discharged outside through the second gas path 52. This reduces
the impact applied to the body of the occupant which is pushed against the air belt
The gas discharged through the second gas path 52 is discharged downwardly
from the buckle 16 so as not to directly hit the occupant.
In this embodiment, even when it is turned upside down, the tongue
14 can be engaged with the buckle 16 to allow the gas to flow in the buckle 16 and
the tongue 14 in the same manner as the above.
In this embodiment, as shown in Fig. 7(b), the opened seal member
61, 42 cross the space between the tongue 14 and the buckle 16, thereby making it
difficult for the gas to leak from the confronting surfaces in the lateral direction.
Figs. 8(a) through 8(c) show structures of the seal members for actively
preventing gas leakage from the confronting surfaces.
In Fig. 8(a), each seal member 61A of the buckle 16A is divided into
two pieces to open. In Fig. 8(b), each seal member 61B of the buckle 16B is divided
into four pieces to open.
It should be understood that the tear line is formed in a U-like shape
for forming the seal member 61 in Figs. 1 through 7, in an H-like shape in Fig.
8(a), and in an X-like shape in Fig. 8(b).
In the buckle 16C shown in Figs. 8(c), 8(d), a seal member 61C has
hood portions 71, 72 to surround three sides of gas spouting out of the first gas
path 51. Fig. 8(d) is a sectional view taken along a line D-D of Fig. 8(c).
As mentioned above, in the air belt device of the present invention,
after the air belt is inflated with gas, the gas is discharged by a discharging
means, thereby significantly reducing the impact applied to the occupant.