Note: Descriptions are shown in the official language in which they were submitted.
BACKGROUND OF T~E INVENTION
The present invention is concerned with a novel seat belt
assembly for use in vehicles, having rich energy absorbing property
and by which the retracting amount by the retractor is increased,
thereby promoting use of the retractor.
The seat belts have generally been employed to mitigate
mechanical shocks to the passengers of vehicles such as automobiles
and air craft resulting to provide safety performance. The seat
belts of this sort were so far studied from various aspects and
angles, and many proposals were so far presented.
In the early days, the belts were manufactured in two-point
type to hold only the waist, but to attain more reliable safety
~059959
performance, the belts were made in three-point type having an
additional belt to hold the shoulder. In recent days there has
been proposed the belts of the type in which the waist belt and
the shoulder belt are made in a continuous form. The belt system
of the aforesaid continuous type has an advantage that they need
just only less retractor units than retractor units required by the
aforesaid three-point type belt system. The modern trend, however,
has been placing increasing demand for the belts to provide moxe
energy absorption, which has resulted in the use of shoulder belts
having large absorption of energy. However, the belts of the aforesaid
continuous type have to be made by joining together an ordinary belt
and a belt having high energy absorption. Hence the joined place
gives an uncomfortable touch feeling to the human body, and comes
into contact with the guide members of the retractor when the belt is
~ being taken up along smooth retracting movement. It is~ thexefore,
desired to make the belt with a single woven fabric without seams to
improve the aforementioned defects. At present, however, to make such
a belt is technically difficult and no satisfactory solution has
been found.
In recent years, increased concern with regard to the improve-
ment of retractors has resulted in the manufacture of retractors of
various types. Such retractors, however, have all been design based
on a prerequisite that the thickness of the belt is equal along the
lengthwise direction, thereby imposing a limit to the amount of taking
up the belt. To increase the take-up amount, the retractor must have
1059959
increased volume~ losing economy in spac~ particularly when it
is used for the vehicles having narrow room. This is a fatal
defect of the belt of the aforementioned continuous webbing type,
losing the balance of whole parts of the vehicle. From such view-
g point, it is an important assignment to increase the take-up space
just with using a retractor of an ordinary size.
SUMMARY OF THE INVENTION
The inventor of the present invention has conducted extensive
study in an effort to solve the aforementioned defects by giving
attention to the aforesaid various points, and has found an
effective means by which the belts can be formed continuously as
a single unit based on the characters required for the shoulder
belt and the waist belt,
It is known, in general, that the shoulder belt requLres less
tensile strength than the waist belt. For example, the waist belt
requires a tensile strength of more than 2700 kg, whereas the
shoulder belt requires only tensile strength of up to 1800 kg.
Particularly, it was confirmed by experiments conducted by the
U.S.National Highway Transport Safety Agency (NHTSA) that where
a belt having property to absorb energy is used for the shoulder
belt, the tensile strength needs not necessarily be 1800 kg, but
may be sufficient if the belt has a tensile strength of 500 kg. It
is, therefore, recognized that the shoulder belt may have less
thickness than that of the waist belt and may have less strength
to sufficiently attain the desired object.
10S995~
The seat belt of the present invention was designed
under the above said situations and comprises a seamless and
continuous webbing having a belt to hold the waist and a belt to
hold the shoulder, characterized in that ~he belt portion of
holding the shoulder of said webbing is thinner and has less
strength than the waist portion of the belt, and further has an
extension property that does not restore to the initial state under
a certain load condition that substantially causes the belt to
extend by a certain length.
The present invention provides a combined vehicle
safety belt shoulder and waist section structure in which the
shoulder and waist sections are woven of warps and wefts and
possess different strength and elongation properties. The shoulder
section is thinner than the waist section, and the shoulder and
waist sections possess a plurality of common continuous warps
some of these continuous warps having high energy-absorbing pro-
perties and possessing a greater weave crimp in the waist section
than in the shoulder section and the waist section possessing a
greater number of warps than the shoulder section.
There is also provided a method of producing this
combined safety belt comprising weaving a continuous band inclu-
- ding successive alternate shoulder and waist sections in which a
plurality of warps interwoven in the waist section float in the
shoulder section, severing the floating warps and severing the
band at alternate junctions of the waist and shoulder sections.
In a further embodiment, the present invention provides
a seat belt for vehicles comprising a seamless and continuous
webbing, wherein a belt which holds the waist and a belt which
holds the shoulder is formed of a seamless and continuous webbing,
characterized in that the shoulder portion (1) of the webbing is
thinner in thickness than the waist portion (2) of the same webbing
and has an extension property that does not restore to the initial
f` ~ -4-
~059959
state under a certain load condition that substantially causes
the belt to extend a certain length, and the waist portion (2)
of the webbing has a greater number of warps than the shoulder
portion whereby the waist portion has larger strength than the
shoulder portion (1~.
The invention is illustrated below with reference to
a concrete embodiment shown in the accompanying drawingsO But it
should be noted that the present invention is not restricted to
the below mentioned embodiment only but permits various design
modifications without departing from the objects of the present
inventionO
BRIEF DESCRIPTION OF THE DRAWINGS
Figo 1 is a perspective view showing an example of
using the seat belt of the present invention.
Figo 2 is a partially omitted perspective view showing
the appearance of the seat belt of the present invention.
Figo 3 is a diagram showing an example of the texture
of the waist belt of the seat belt of the present inventionO
Figo 4 is a diagram to show an example of the texture
of a selvage of the seat belt of the present invention.
Fig. 5 is a vertical cross-sectional view showing the
texture of Fig, 3 of the waist belt of the seat belt of the pre-
sent inventionO
-4A-
'. J
1059959
Fig. 6 is a diagram showing an example of the texture of
the shoulder belt o~ the seat belt of the present invention.
Fig. 7 is a vertical cross-sectional view showing the
texture of Fig. 6 of the same seat belt.
Fig. 8 is a vertical cross-sectional view showing the texture
at the boundary part of the waist belt and the shoulder belt of the
seat belt of the present invention, and
Fig. 9 is a diagram showing curves of load and extension of
the waist belt and the shoulder belt of the seat belt of the
present invention.
DESCRIPTION OF THE PREFERRED E~ODIMENTS
Fig. 1 shows a diagram to illustrate an example in which a
seat belt of the present invention is employed, in which the
reference numeral 1 stands for a shoulder belt~ and the re~erence
numeral 2 represents a waist belt. These two belts 1 and 2 form
a belt made of a single continuous webbing via a boundary part 3
as shown in Fig. 2. The shoulder belt 1 is thinner than the waist
belt 2. The belt composed of these shoulder belt l and waist belt 2
will usually have a retractor 4 and a fastening fitting 5. The
belt is passed through a slidable tongue piece 6 locating as a
middle suspending matter; the slidable tongue piece 6 will be en-
gaged with a buckle 7 which is suspended to an anchorage hole 8
selected within the vehicle inside. The reference numeral 9
is a member to guide and direct the shoulder belt position 1
that was pulled out from the retractor 4 fixed on some place of the
:1059959
side wall. The member 9 is not necessary if the retractor is
provided here at this position. Also, the reference numer~llO
represents a seat in the vehicle.
Figs. 3 to 5 are diagrams to show an example of weaving
waist belt 2, Fig. 6 and 7 are diagrams to show an example of
a woven texture of the shoulder belt 1, and Fig. 8 shows an
embodiment of a texture at the boundary part 3 between portion
belt 1 and 2. In the drawings~ the reference numerals 11, 12, 13, 14,
15 and 16 are warps in a complete texture. The above warps are
arrayed in many number in parallel, and to both sides thereof are
added warps 21, 22, 23 and 24 having selvage shown in Fig. 4 to
determine the belt width of the present invention. The reference
numerals 31 and 32 are warps having smaller elongation than the
warps 11 to 16. Further, the reference numerals 41, 42, 43, 44,
45 and 46 are wefts in the waist belt 2, and the reference numerals
51, 52, 53, S4, 55, 56, 57 and 5~ are weftsin the shoulder belt 1.
In Figs.3 to 5, the aforesaid warps 11 to 16 and 31, 32 are
crossed and interlinked by the wefts 41 to 46 by way of triple
weaving shown in Fig. 3 to form the waist belt 2. In this case,
the selvage texture shown in Fig. 4 is added to both sides of
fabrics in Fig. 3O In Figs.6 and 7, the warps 11, 12, 14 and 15
among the warps 11 to 16 and 31, 32 in the aforesaid waist belt 2
are crossed and interlin~ed together with the wefts 51 to 58 and
double weaving of wefts diagramatized in Fig. 6 and further the warps
13 and 16 are fioated, without being woven and arrayed in parallel,
--6--
lOS9gS9
outside of the aforesaid crossed and bonded texture. The warps
31, 32 are crossed and interlinked with the wefts in the afore-
said waist belt 2, and are running as core yarns being retained
inside of the texture composed of warps 11, 12, 14, 15 and
S wefts 51 to 58, as seen in Fig, 7; the warps 31, 32 are not
exposed outside of the texture. As mentioned above, the fabric
of the shoulder belt l of the present invention is formed by
the interrelated fu~ tion among the warps 11, 16, 31, 32 and wefts
51 to 58.
The aforesaid selvage texture diagramatized in Fig.4 is also
added to both sides of the shoulder belt 1. Here the aforesaid
waist belt 2 and the shoulder belt 1 are constituted as a single
continuous webbing without seam. In this texture, the boundary
part 3 between the two belts l and 2 is shown in Fig. 8. That is,
the warps 11, 12, 14, 15, 31 and 32 forming the waist belt 2
are taken over by the fabric of the shoulder belt 1. The floating
warps 13 and 16 are cut away at a part A where they appear out of
the fabric. The cut-away part is then removed appropriately, and
the position A at the end is then dyed and transferred to the
position B of Fig. 8, and then buried and retained in the
texture of the waist belt 2. In this wayt a continuous seamless
webbing isformed with the waist belt 2 and the shoulder belt 1
together. In the foregoing description9 the warps are preferably
cut away in an amount within the range of 10 to 40~/O in relation
to the thickness and strength of the belt, so that the thickness
-7-
1059959
is reduced into appropriately favorable value relative to the
thickness of the waist belt 2.
Although the foregoing description has dealt with the transfer
from the waist belt 2 toward the shoulder belt 1, it should be
noted that the webbing of the present invention is made for
manufacturing a long ~xture in which the waist belt 2 and the
shoulder belt 1 are repeated alternately; the same structure is
rep eated from the shoulder belt 1 toward the waist belt 2.
However, here, as for the order of wefts, the weft 41 in place
of we ft 46 in the waist belt 2 is woven next of the weft 58 of
the shoulder belt 1. Materials of wefts and warps for use in the
webbing texture of the present invention may be thermoplastic
synthetic fibers such as nylon, vinylon, polyester, polyprene
esters, and various fibers such as viscose rayon, cott on,-hemp,etc.
Among the above thermoplastic synthetic fibers, particularly
preferred examples are nylon and polyester fibers. These fibers
may often be employed by being mixed t ogether. The warps 31 and
32 that serve as core yarns may be made of a polyester fiber,
vinylon, metallic fiber and glass fiber. Particularly preferred
example may be a reformed fiber that is known as fiber B having
less elongation. The core yarns, however, are selected best by
comparison with the warps constituting the fabric.
The webbing by which the waist belt 2 and the shoulder belt 1
are connecte~ for a single unit, is terminated to the aforesaid
retractor 4 and to the fastening fitting 5, and is used for a seat
1~59959
belt as shown in Fig. l. Also, in this case, the mounting
positions of the retractor 4, fastening fitting 5, buckle 7 and
indoor member 9 cannot be limited to the positions shown in
Fig. l but may be mounted at any appropriate positions. In
the present invention, in particular, the shoulder belt l is
thin and is allowable to be mounted directly on the seat lO,
- which possibility is an advantage of the belt of the present
invention.
When mechanical impact is applied to the aforementioned
seat belt, the waist belt 2 havir.g large strength and thickness
securely holds the human body, and the shoulder belt l which is
made thin and has smaller strength undergoes stretch easily
when the impact is applied, whereby the core yarns are broken
step by step in order, and then the determined load is reached and
further acting point exten~ to a set point P shown in Fig. 9 to
absorb the energy exerted on the human body. Fig. 9 shows this
state, wherein the load and extending elongation degree exerted on
the waist belt 2 as measured under the Standard, isdiagramatized in
. .
diagram (a). The diagram (a) shows less degree of elongation and
less work done. However, if the elongation of the shoulder l
is set at 30%, for example, under a determined load of 300 kg, -
the core yarns will be broken down step by step at around 300 kg
loadèd, so that the flat portion such as in the diagram (b) may
continue from an extension degree about 4 to 8% started to a set point
P of about 30% indicated there. Furtherl if the loading is increased
lOS9959
up to 1130 kg speci~ied value under the Spec. MVSS, the extension
reaches about 45%, at which the belt does not restore to the
initial state (length) even after the load o~ 1130 kg is removed;
the amount of work done is very large as compared to that of the
waist belt 2. From the abovementioned fact, even a single
continuous seamless webbing has the performance being comparable
to a conventional three-point type seat belt employing energy-
absorbing belt ~or a shoulder belt. The fact proves that the
seat belt by the present invention has excellent performance.
Here the aforementioned predetermined load and set point
will be selected depending upon the waist belt 2 and the shoulder
belt 1 of the belt over the range of 150 to 1000 kg and from 20~/. to
40% of the point P.
As mentioned above, the seat belt of the present invention is
made of a continuous and seamless webbing including the waist
portion 2 and the shoulder portion 1, contributing to reduce the
number of retractorsthat will have to be installed in the vehicle room.
Moreover, since the webbing of shoulder portion 1 can be made thin
and can be taken up by the retractor, it is allowed to make the
retractor in small size or to have both the shoulder portion 1 and
the waist portion 2 contained in a conventional retractor case.
Therefore, in addition to reducing the number of retractors to be
used, reasonable use of the retractor can be promoted and the seat
belts can be attached to the vehicle room properly. In addition,
the seat belt by the present invention, which is made of a single
-10-
1059959
seamless and continuous belt, exhibits excellent performance to
absorb energy which is comparabl to conventional three-point
type energy-absorbing belts. Besides, the belt by the present
~ in~vention without seams permits the slidable tongue piece to
slide smoothly, so that said slidable tongue piece can be
retained at any proper and balanced positions to fasten the belts.
In case of collision, the impact due to the collision is dispersed
between the waist belt and the shoulder belt owing to free sliding of
the slidable tongue piece to secure the safety of the human body.
The slidable tongue piece also gives improved contact feelin~ to
the human body. As mentioned in the foregoing, the seat belt by
the present Lnvention possesses various e~cellent effects exhibiting
rich energy-absorbing performance and meets the demand required by
modern vehicles.
While there have been described and illustrated preferred
embodiments of the present invention it is apparent that numerous
alterations, insertions and additions may be made without departing
from the spirit thereof.
