Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to a safety belt for restraining
of persons sitting in a seat of a motor vehicle, boat, aircraft
or other form of transportation.
Known motor vehicle safety belts are of basically two
types, the static belt and the inertia belt, Usuall~, with both
types of belt, a length of webbing is entrained diagonally across
the chest of the seat occupant and across his lap. With a static
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belt, once it is tightened and tensioned acroSs the body of the
; seat occupant, it is not adjustable so that for example~ the seat
occupant cannot lean ~orward in his seat. This has certain dis~
advantages which are overcome with the inertia belt in which one
end of the belt is wound upon a rotatable reel spring biased in - -
the direction of belt wind up. Under normal conditions~ the ;
reel is free to rotate against the spring bias so that seat
occupant can lean forward in his seat, the belt unwinding from
the reel. Inertia actuated locking mechanism is provided so that
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under emergency conditions the reel islocked against rotation.
The present invention provides a safety belt which has
the advantages of an inertia belt, allowing the seat occupant ; -
:. ~ . . :, : ~ some freedom of movement, but which does not need a comparatively~
expensive inertia locking mechanism.
`~ The present invention provides a safety belt comprising a ~
length of webbing with a first end portion, an intermediate por- "
` tion and a second end portion, said intermediate portion providing
lap and diagonal parts of said safety belt, said lap part being
provided for restraining the major body weight of a seated occu~
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pant and diagonal part being provided for restraining the upper
; torso of said occupant, said first end portion being coupled to
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` said second end portion so that the safety belt can be fastened
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about said occupant to restrain said occupant in a substantially
upright seated posture during deceleration whereby, during `
deceleration, as said first end portion is paid out, said second
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end portion is taken up and vice versa, the rate of take up and
pay out of said first end portion bei~ng different ~rom the rate
of pay out and take up of sald second end portion whereby, during
deceleration, said rates of pay out and take up of said end por-
tions co-operate with the loads appI~ed to said lap and diagonal parts ;~
to restrain said occupant in the substantially upright seated posture,
In use, the webbing can be entrained, from the end portions
which are coupled, in one direction slidably through an upper anch~
orage point and in the other direction slidably through a lower
anchorage point, the webbing at each anchorage point being turned -~
through an angle which is greater than 270, ~ith the anchorage
points located on the same side of the seat, the webbing can be entra ~ d
; diagonally across the chest and across the lap of the seat occupant and
attached to an anchorage point on the other side of the seat. -
In one arrangement, the terminal end of the first end portion
` of the webbing is fixed relative to the vehicle chassis The first ~ -
; end portion of webbing running from that ~ixed end is then entrained
around a pulley and back upon itself, the second end portion of the
webbing being fixed to a yoke in which the pulley is freely rotat~ -
; 20 able. With such an arrangement there is a 2:1 ratio between the
rate of pay out and take up of the webbing around the pulley and ;
of webbing attached to the pulley yoke. A weight may be attached to
the yoke to ensure that a light bias is applied to the portion of
webbing entrained across the occupant's torso and to ensure that excess
webbing is taken up as the occupant leans back in his seat.
In an alternative arrangement, the first end portion of the ;
webbing is attached to and wound up on a first drum an~ the second ``
; end portion of the webbing is attached to and wound up on a seoond drum the
first and second drums being coupled for joint rotation. The d~ms have differ-
- 30 ent diameters and may be coupled to rotate at the same angular speed; for example
the drums may be fast on a common shaft or may be coupled together by
gearing. One or both drums may be biased, for example, by clock springs to
apply a light bias to the webbing and
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to ensure excess webbing take-up. The relationship between the
first and second drums may be such that a considerable length of
webbing must be paid out from the first drum before a point is -
reached where the webbing is correctly tensioned across the torso
oE the seat occupant. In this case, the webbing is ~tored on the
first and second drums in respectl~e and single directions of rota- ;~
tion. The need to pay out a considerable length of webbing may be ;
a cause of annoyance to the user in ~ew of the time required to
adjust the belt. Ihis prDblem may be overo~ by attaching the terminal ends
of the first and second end portion of the webbing to respective
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; first and second drums which are coupled for rotation, the webbing
~ being stored on said drums such that it is initiallypaid out by both
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the first and second drums until the terminal end of the webbing is ~
reached on the second drum, whereupon the webbing may be further -
paid out by the first drum and taken up by the second drum. This
rèduces the time taken to pay out sufficient webbing for location
across the torso of the occupant and hence the time taken to reach
a point where the webbing is correctly tensioned, The first and `
second drums may have different diameters and be coupled by a one:
~ 20 one gear ratio so that they rotate with the same angular veloclty.
;1 Preferably, the ~ebbing is stored on the first the second drums in~
opposite rotary directions, the length of the webbing being selec-~
ted with regard to the size o the occupant such that the terminal
end of the webbing is reached on the second drum, as it is paid out
therefrom, before the webbing is correctly tensioned. The webbing
is then taken up by the second drum in the same direction of rota-
tion as the webbing is stored on the first drum. ;
In another arrangement, the webbing end portions are wound
'~ on drums of the same diameter which are coupled so as to rotate
; 30 together but at different angular speeds.
In a further arrangement, the first end portion o~ the webbing is
secured to an anchorage m~er and is then entra~d about loop forming m~ns, ~`
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the second end portion of the webbing being ~ound on a first drum.
An additional length of webbing is secured between said loop form~ ;
ing means and a second drum coupled for rotation with the first drum.
Preferably, the loop forming means comprises a pulley which
is suspended by the loop formed in the first end portion of the
webbing. The intermediate portion o~ the webbing is intended to
extend across the chest and lap of the seat occupant, a second loop
formed thereby being secured to a second anchorage member. The
second anchorage member may be part of a releasable fastener such
as a tongue and buckle. The lap part of the intermediate portion
of the webbing may be entrained abaut a third anchorage member
which, in use, is positioned adjacent the first drum
In this case, it is an advantage for the webbing to be
initially paid out from the first and second drums respectively
until the terminal end of the length of webbing is reached on the
first drum, the additional length of webbing thén being further
paid out by the second drum as the respective length Oe webbing is
taken up by the first drum.
The first and second drums may be coupled for rotation by
means of gearing which provides a 2:1 drive ratio with regard to
the loop formed in the first end portion of the webbing,
In use, the first and second drums may be commonly mounted at
an anchorage point on the vehicle. Alternatively, they ~ay be left free.
One or other of the drums may include biasing means for -~
causing the webbing to be rewound on the respective drums.
Different embodiments of the invention will now be described
` with reference to the accompanying schematic drawings, in which:
Fig. 1 shows a first embodiment illustrating the basic
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principal of a safety belt in accordance with the invention, -; -
Fig 2 shows an alternative embodiment,
Fig. 3 shows how the belt of Fig 1 may be entrained
across the chest and lap of a seat occupant,~ ;
Fig. 4 shows the safety belt layout of Fig. 1 in its
storage position,
Fig. 5 shows a further embodiment,
Fig. 6 and 7 show the-embodiment of Fi~. 5 at different
stages Or operation, ; `
Fig. 8 illustrates another embodiment,
Fig. 9 and 10 illustrate different stages of operation
of the belt shown in Fig. 8, and
~; Fig. 11 is a perspective view~of a detail of a modifi-
cation to the arrangement sho~n in Fig. 8. -
Re~erring to Fig. 1, a continuous lengkh o~ webbing
1 is fixed at an upper end 2 to the vehicle chassis 3, for
example the door pillar. From its fixed end, the webbing ;
...
extends downwardly and is entrained a~ound Q rotatable roller
4 freely rotatable in a yoke 5. ~he webbing then extends
upwardly and passes slideably over a ~ixed upper anchorage
' I . .` ~ member 6. This upper anchorage member 6 i3 fast with the -
vehicle chassis, for example the door pillar, and may be
; o~ con~entional form.
The loop of webbing indicated at 7 in use, as shown ~`
in Fig. 3, passes diagonally aoross the chest of the seat
occupant, as indicated at 8 and, as indicated at 9, across
;the lap of the seat occupant, the loop at 10 being releasably
attached to an anohorage point at the side of the seat.
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- The webbing slideably passes over a lower anchorage `'-
member 11, fixed to the vehicle chaæsis 9 for example to the '~' ,'
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~loor o~ the vehicle. The webbing then extends upwardly ;~ ,
and its other end 12 is attached to the yoke 5. A weight
13 is carried by the webbing just below the end 12 which
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is attached to the yoke 50 '
With arrangement shown in Fig. 1, i~'the webbing passing
over the upper anohorage member 6 is pulled down in the direc- ' ,
tion indicated by the arrow A, the pulley 4 and yoke 5 will ~'
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move upwardly so that the end 12 of the webbing also moYes ~'
upwardly, but the rate Or withdrawal of the webbing around '',~
the pulley 4 and over the anchorage member 6 will be twice
the rate at which the end 12 of the webbing moves upwardly. -
Thus, the size of the loop 7 of webbing will be increased. ~-
Conversely3 if the ~ebbing is pulled in the direction of
the arrow B around the lower anchorage member 11, then the
yoke 5 and webbing end 12 will move down but at half the
rate at which webbing moves over the upper anchorage member
6, so that the size o~ the loop 7 will be reducedO
From'the foregoing description it will be appreciated ~,
' that~since the size of the loop 7 can be adjus,tedg so'the
safety belt can be adjusted to fit around a small or large '~
pe~son. Furthermore~ ~hen a person sitting in the vehicle '~ ,
,' ' seat wishes to lean forward, this movement may be ~acilitated '~,
by pulling down on the length 8 of webbing ~see Fig. 3~ and
, when the occupant sits back the webbing will be tensioned '~
- again under the in~luence o~ the weight 13. ;-
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' On collision or impact o~ the vehicle~ the seat occupant's
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body will be thrown forward in the direction of the arrow indicabed
at C and the webbing tensioned but there is no tendency, under -
these conditions, for the size of the loop 7 to increase, During
an accident, the whole body moves forward under deceleration
applying loads simultaneously to the lap and diagonal portions ;
8, 9 of webbing 1 As the weight of the body restrained by the
lap portion 9 is considerably greater than the body load restrained
by the diagonal portion 8, the forces in the belt system balance
out and the body moves forward with vertical vertebrae. Thus the
occupant is instantaneously and positively restrained in his seat.
When the safety belt is not in use, the weight 13, under
gravity, falls and the webbing is neatly tensioned between the two
anchorage members 6 and 11, as seen in Fig. 4.
An alternative arrangement of safety belt is shown in Fig. 2,
in which like numerals indicate like parts as shown in Fig. 1.
In the arrangement of Fig. 2, one end of the webbing is
attached to and wound around a comparatively large diameter drum
20. The other end of the webbing is attached to and wound around
a comparatively small diameter drum 21. The two drums are essent~
ially mounted for common rotation. For example, they are fast on
a common shaft which is rotatably mounted on an anchor plate not
shown, which is secured to the vehicle and the webbing is wound
clockwise on the drum 20 and anti-clockwise on the drum 21, or
vice versa. It will be appreciated that with this arrangement,
when the two drums are rotated in one direction, for example -~
clockwise as shown in Fig. 2, webbing will be paid out from the
drum 20 and taken up on the drum 21 but because of the difference -
in diameters of the two drums, the rate of pay~out from the
drum 20 will be greater than the rate of take~up on the drum
21, thus the effective size of the loop 7 is
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increased. When the drums are rotated in the anti-clockwise
direotion, the size of the loop 7 will be reduced because ;~
the rate of take-up on the drum 20 is greater than the rate
of pay-out from the drum 21,
Instead of having the two drums 20 and 21 fast on a
common sha~t, they may be mounted in a suitable housing
one above the other and coupled together with gearing so
that they rotate together.
In another arrangementJ not illustrated, the ends o~
the webbing may be fast with and wound upon two drums of
the~same diameter which are coupled by gearing so as to
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rotate together but at di~ferent angular speeds so that
the rate of take-up and pay-out from one drum is different
from the rate of pay out and take~up on the other drum.
In all the arrangements where the webbing ends are ~
attached to and wound upon drums, spring biassing may be `
provided to rotate the drums in the appropriate direction
to reduce the effecti~e size of the loop 7 of webbing. The
~provision of such a spring bias firstly ensures that the
loop 7 of webbing entrained acros~s the torso of the seat
`~ occupant is~always lightly tensioned and, secondly, ensure~
; that when the safety belt is not in use the webbing is wound
up and the loop 7 tensiQned between the upper and bwer anchor-
age members 6 and 11.
Furthermore~ with the arrangement shown in Fig. 1, a
` spring bias may be used in combination with or to replace
the weight 13, to ensure that the loop 7 is always maintained ~,~
under slight tension
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; Referring to Fig. 5, a length of webbing 21, including
~; a chest portion 22 and a lap portion 23, is entrained over
pulleys or guides 24, 25 respectively mounted in the roof
and on the floor of a veh-icle. Webbing 21 is threaded through
a running loop 30 forming part of a buckle 33. One end of
the webbing 21 is stored on a first reel 26 and the~other
end on a second reel 27. The diameter of reel 26 is greater
than the diameter of reel 27, for example, in the ratio 2~
The reels are~connected to respective toothed wheels 28, 2g
of the same diameter, which are meshed so that reels 26, 27
rotate with the same angular velocity. However, due to the
di~ference in the diameters of reels 26,-27, the respective `
rates of take up and pay out are different. ~-
The length of webbing 21 may be adjusted by suitable
means, such as a sliding buckle (not shown), with regard to
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the torso of the seated occupant, so that the end 32 o~ the
webbing 21 is reached on reel 27 at a predetermined point ,~
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when the webbing is paid out ~rom both reels 26~ 27. This
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`; stage is illustrated in Fig. 5 and it may be reached as the J ,:, 20 ~ occupant drws together a tongue;31, which is ~ixed to the
floor o~ the vehicle, and~the buckle ~. Before this point
is reached, as illustrated in Fig. 6, the webbing 21 is paid
out rrom both reels 26, 27 due to the opposite direction of
rotation o~ the webbing stored on the respective reels. After
the predetermined point has been reached, the webbing is wound -
-~- up on reel 27 as it is paid out from reel 26, the direction ~
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of belt wind-up being the same on both reels as illustrated
in Fig. 7. The webbing 1 is then~tightened across the torso
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of the occupant with some o~ the webbing rewound on reel 27.
It is essential that some of the webbing 21 has been rewound
on reel 27 before the safety belt is in a safety restraining
condition and this may be observed by the occupant if a length
of the webbing, which extends ~rom reel 27 to a predetermined
point beyond pulley 25 (with the webbing in the state shown
in Fig. 1), includes a marker. For example, the latter length
o~ the webbing 21 may be coloured or it may include a coloured
stripe. Alternatively, a coloured marker band may be ~ixed
to, or ~orm part of the belt and be located at the predeter~
mined point. The occupant then knows that the webbing~has
been rewound on drum 27 when the marker has disappeared from
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view, or lies between pulley 25 and reel 27. When the webbing
is in this state, the occupant may normally lean ~orward,
the webbing being paid out ~rom reel 26 and taken up by reel
27. However, in an accident, when the occupant is accelerated
with respect to his seat, the reels 26~ 27 do not revolve
and the webbing 1 acts as a restraint.
Essentially, the end o~ the lap portion 23 o~ webbing
21 is reached on the driven reel 27-before ~he buckle 33 ~-~
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is attached to the tongue 31. This ensur~es that some o~ ~
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- the webbing 21 has been rewound on reel 27 when the belt
is secured for safety restraint.
Reel 26 may be coupled to a rewinding mechanism, such
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as a clock spring, automatically to retract the webbing 21
when the buckle 33 ls released ~rom the tongue 33. ;~-
To reduce ~riction between the lap portion 23 and the
clothing of t~)e user, a sleeve made of~ or lined with low
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~riction material may be attached to the buckle 33
through which the lap portion 23 is threadedO The sleeve . : .
then res~s on the users lap allowing the lap portion 23
to slide through it~ ~ .
Re~erring to the Fig 8D one end o~ a firæt length o~
webbing 41 is secured to an upper anchorage point by means
I Or a pivotally mounted anchor bracket 42. Bracket 42 may
be secured3 ~or example, to the upper portion Or the door
pillar of a vehicle. Webbing 41 i8 entrained about loop ..
forming means comprising the bracket 42 and a freely suspended
pulley 39 fitted in a yoke 43~ The belt 41 passe~ downwardly
~rom bracket 42~ under the pulley 39 and back to a running : ~
loop in bracket 42 be~ore it is entrained across the chest ~.
of the seat occupant. The running loop and anchora~e loop
of bracket 42 may be separate components w~ich are mounted
on the same mountin~ bolt;. . .~ .
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After passing diagonally aoross the ohest of the.seat .~
occupant, the webbin~ 41 paæses throu~h a.r~nning loop.in .:.
a tongue 38 which releasably~engages a buckle ~4. -~uckle
44 is mounted on a stalk which i8 ~ecured to the transmission
tunnel:~5 oP the uehicle by means of a bol~.46. Webbing . -:
. 41 then passes over the lap of the seat~occupant~ through.
a further running loop, which is provided by a bracket 47 ::
anchored to the side Or a vehicle~ and is then wound on a :.
- 25 first drum 48. The word "drum~ i8 used gener;cally herein ~`
to couer, for example, a rotatable member on which the webb~ng
may be wound including a spindle,-sha~t or rolls~0
. Drum 4B is mounted ~or rotation with a second drum 49
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by means of meshed gears 50, 51. Drums 48, 49 are mounted
on a frame 53 which is also anchored to the side of the
vehicle. At least one of the drums 48, 49 is biased in a
direction to retract the webbing 41, for example, by means
of a coil spring ~not shown). Both drums are o~ similar
diameter and are geared together so that as one drum rotates,
the other rotates at substantially the same velocity.
; A second length of webbing 52 has one end wound on and
fastened to drum 49, the other end being secured to yoke
43. An adjuster 56 is provided to allow people of different
sizes to use~the safety belt arrangement and to cater for
extremes of seat adjustment.
Referring to Figs. 9 and 10, the manner in which the
lengths of webbing 41, 52 are wound on the respective drums
48,~ 49 wilI be explained in greater detail. Fig. 9 shows
the operating state of the drums when3 for example, the
webbing is stowed and is not worn by the user. In this
case, the-length of webbing 52 is retracted on~ and wound
about drum 49, the length of webbing 41 also being retracted `~
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on and wound about drum 48 but having a relatively smaller
number of turns ~hen the seat occupant puts the belt on,
he grasps the webbing 41 or the tongue 38 at the bracket
42 and pulls it across his torso. This initially causes
both drums 48, 49 to rotate in a sense to pay out the len~ths
of webbing 41 and 52. However, when all of the webbing 41
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has been paid off from reel 48, the sense o~ winding changes
and thereafter the webbing 41 is wound on drum 48. The latter
operational state is shown by Fig. 10. The belt i8 worn
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when the drums are in the operating state shown by Fig. 10.
The optimum ratio between the pay out and take up of
the ends of the length of webbing 41 is about 2:1 having regard
to the loop formed by bracket 42 and pulley 39.
Referring to Figo ll, the pulley frame 53 acts as a
lower anchor point which is provided with a pivotally mounted
running loop 54. Loop 54 is shown pivoted at a point midway
between the walls of the frame 53 but other arrangements
are possible, ror example9 a loop pivoted close to one end ~ ~
of the slot. Gears 509 51 are~normally provided with a cover ~ -
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(not shown).
A spring (not~shown) o~ the type normally used in inertia
~eels acts to bias the upper drum 49, a housing 55 being pro-
vided to prevent damage to the sprine. In practice, less
turns are required from the sprine~than from an equivalent
inertia reel spring (typically ten turns on the former compared ~
with sixteen on the latter~. This enables either a lighter --
- and cheaper spring, or a spring with a flatter rate to be
used to provide greater comfort.
The ~rame 53 need not be attached to the vehicle but
left free. In this case9 the weight of the drum assembly ~ ;
- and the~level of bias exerted~by the~rewind spring needs to
~ be taken into consideration. For example, when the length
` ~ of webbing 41 is worn by~the user, the lower drum 48 will ~ -~
pay off webbing until the change over point is reached ~between
-the state shown in Figs. g and 10) but it will not then rotate
any ~urther.
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