Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02300027 2006-08-17 ~
RESTRAINT SYSTEM FOR A SCHOOL BUS SEAT
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
The present invention is in the field of restraint systems used to provide a
protective passenger environment.
DESCRIPTION OF THE PRIOR ART
Conventional seat belt systems combining a lap belt and an upper torso belt
are well known. These three-point restraint systems are usually used with
seats
offering rigid support for the belts. As typically used in a vehicle, the
three-point
restraint system consists of single belt having its opposite ends mounted to a
pair
of retractors with a seat belt tongue connected to the belt intermediate to
the belt
ends. The tongue may be swung across the person and engaged with a buckle
affixed to the seat thereby positioning one portion of the belt across the lap
and
another portion of the belt across the upper torso. In some systems, only one
end
of the belt is mounted to a retractor while the other end is anchored to the
seat or
vehicle. Seat belts are active restraint devices, requiring a passenger to
actively
engage the restraints for them to be effective.
School bus passenger seats usually do not employ active restraint safety
devices, but instead rely on a passive restraint seat design. School bus
passenger
seats are built to specifications conforming to the safety standards set by
the
National Highway Traffic Safety Administration, DOT. These are codified as 49
C.F.R. Ch.V, 571.222, Standard No. 222, and require that the seat back bend
or
deflect forward when a force is applied to the rear of the seat back. The code
further specifies that 4000W inch-pounds of energy must be absorbed within a
maximum forward deflection of the seat back of 14 inches and 2800W inch-
pounds be absorbed within a maximum rearward deflection of the seat back of 10
inches where W represents the number of seating positions for which the seat
is
CA 02300027 2000-03-06
2
designed. 49 C.F.R.. Ch.V, 571.222, S5.1.3-5.1.4. The code specifies a
passive
restraint system, and does not require any sort of active restraints, such as
a two-
point passenger restraining lap belt or a three-point passenger restraining
lap belt
and torso harness combination. Children riding the school bus are protected in
head-on collisions by the seat back in front of them deflecting forward and
absorbing some of their forward momentum.
Vehicles with deforming or deflecting seats provide special problems
regarding the integration of active restraint seat belt systems. Passive
restraint
systems are designed to protect a passenger who has been thrown forward by
having the impacted seat back deflect upon impact of the thrown passenger and
absorb some of their momentum. In a school bus seat combining active and
passive restraint systems, both of the restraint systems have to be able to
perform
their functions and the seat must still conform to the regulations set forth
in 49
C.F.R.
In U.S. Patent 5,746,476, there is disclosed an automotive seat having a
tower frame associated with the harness to transmit impact loads to the floor.
Despite the prior devices, there is still a need for increased protection for
children
riding the school bus in an emergency or crash situation. The addition of an
active
restraint system, sucti as a three-point lap belt and torso harness
combination,
provides enhanced passenger protection in a head-on crash as well as provides
passenger protection in a broadside collision and/or roll situation. Disclosed
herein
is a three-point lap belt ancl torso harness passenger restraint system that
is
compatible with the pivoting and deflecting seats required by 49 C.F.R.
A further need is to provide a restraint system for a school bus seat that is
operable to remove slack in the belt during rapid vehicle deceleration. The
conventional method is to employ pretensioner devices connected to the belt
which
rapidly withdraw belt once a pyrotechnic charge fires upon sensed vehicle
deceleration. Such pretensiorier devices may be mounted beneath the seat. In
the
case of a school bus seat, the addition of a pretensioner device reduces
storage
space beneath the seat. In lieu of a pretensioner device, we have devised a
device
built into the seat to automatically takes up slack in the belt as the
restrained
CA 02300027 2000-03-06
3
passenger moves fonvard with the tower frame assembly during vehicle
deceleration.
CA 02300027 2000-03-06
4
SUMMARY OF THE INVENTION
One embodiment of the present invention is a restraint apparatus for a
passenger in a vehicle having a seat frame mountable to the vehicle. The frame
includes a seat portian and a back portion. The back portion has a bottom end
portion, and a top end portion with the back portion pivotable forwardly about
the
bottom end portion toward the seat portion upon crash force applied to the
back
portion. A retractor has a web extending therefrom through a web guide. The
web
has a chest portion aiid a lap portion positionable across a passenger located
on the
seat portion. The retractor has an unlocked position and a locked position. A
first
lock is mounted to the web and a second lock is mounted adjacent the seat
portion
and lockingly engageable with the first lock. A tower is mounted to the frame
and
movable with the back portion. A web tensioning arm is mounted to the frame
and
is moved by the tower to engage the web to take up slack in the web as the arm
moves upon crash of the vehicle.
It is an object of the present invention to provide an active restraint system
compatible with existing passive restraint school bus seats and the present
Federal
safety regulations.
A further object of the present invention is to provide an active restraint
system for school bus passengers.
It addition, it is an object of the present invention to provide a device for
removing or taking up slack in the restraint belt during vehicle deceleration.
Related objects and advantages of the present invention will be apparent
from the following description.
CA 02300027 2000-03-06
13RIEF I)ESCRIPTION OF THE DRAWINGS
FIG. 1 a is a perspective view of a bench seat frame incorporating a first
alternate embodiment of the present invention.
FIG. 1 b is the same view as FIG. 1 a with the addition of an attached seat
belt assembly.
FIG. 2a is a partial side elevation view of the embodiment of FIG. 1.
FIG. 2b is a front elevation view of the tower member of the embodiment
of FIG 1.
FIG. 2c is a s:ide elevation view of the embodiment of FIG. 1 coupled to a
bench seat frame.
FIG. 2d is a side elevation view of the embodiment of FIG. 1 mounted
below a bench seat frame.
FIG. 3a is an enlarged fragmentary front elevation view of the slot in the
tower member of the embodirnent of FIG. 1.
FIG. 3b is an enlarged side fragmentary elevation view of the slot in the
tower member of FIG. 3a.
FIG. 3c is an enlarged side fragmentary elevation view of the intersection
of the tower member and the connecting member, showing the rotation of the
tower member.
FIG. 4a is a perspective view of a bench seat frame incorporating a second
alternate embodiment of the present invention.
FIG. 4b is the same view as FIG 4a with the addition of an attached seat
belt assembly.
CA 02300027 2000-03-06
6
FIG. 5a is a side elevation view of the embodiment of FIG. 4a.
FIG. 5b is a side elevation view of the embodiment of FIG. 4b.
FIG. 5c is a partial front elevation view of the embodiment of FIG. 4b.
FIG. 6a is a side elevation view of the connecting member of the
embodiment of FIG. 4a.
FIG. 6b is a front elevation view of one vertical piece of the tower member
of FIG. 4a.
FIG. 6c is a side elevation view of one vertical piece of the tower member
of FIG. 4a.
FIG. 7 an enlarged perspective view of the crossbar member of the second
embodiment of FIG. 4a.
FIG. 8 is a top plan view of the embodiment of FIG 4b.
FIG. 9 is a perspective view of the preferred embodiment of the bench seat
frame with a belt slack take-up device.
FIG. 10 is a fragmentary enlarged perspective view of the left side of the
bench seat frame of FIG. 9.
FIG. 11 is a fragmentary cross sectional view of the seat portion and back
portion of the frame in a pre-crash condition taken along the line 11-11 of
FIG. 9
and viewed in the direction of the arrows.
FIG. 12 is the: same view as FIG. 11 only showing the back portion tilted
forward in a crash condition with belt slack taken up.
FIG. 13 is a fragmentary top view of the bench seat of FIG. 10.
FIG. 14 is a cross sectional view taken along the line 14-14 of FIG. 10 and
viewed in the direction of the arrows.
FIG. 15 is a perspective view of the preferred embodiment of the seat
including the seat cushion
CA 02300027 2000-03-06
7
DESCRIPTION OF THE PREFERRED EMBODIMENTS
For the purposes of promoting an understanding of the principles of the
invention, reference will now be made to the embodiments illustrated in the
drawings and specific language will be used to describe the same. It will
nevertheless be understood that no limitation of the scope of the invention is
thereby intended, such alterations and further modifications in the
illustrated
device, and such further applications of the principles of the invention as
illustrated
therein being contemplated as would normally occur to one skilled in the art
to
which the invention relates.
Referring now more particularly to the drawings, FIGS. 1 through 3 show a
three-point restraint system 120 incorporating a first alternate embodiment of
the
present invention. The restralint system 120 is designed to restrain two
passengers
sitting side by side. The restraint system 120 includes a tower member 121
movably coupled to a connecting member 122, and is adapted to be mounted to a
conventional school bus passenger seat frame 123. Tower member 121 is adapted
to move independently relative to seat frame 123. Preferably, tower member 121
is adapted to pivot relative to seat frame 123. The members comprising
restraint
system 120 are formed from steel or any convenient structural material. Seat
frame 123 includes a seat support portion 124 connected to a seat back portion
125
and also connected to a leg portion 126 adapted to be affixed to a surface,
such as
the floor of a school bus. Seat support portion 124 is typically formed from
one or
more bent metal tubes 127 and includes a front portion 128 and a rear portion
129.
Seat support portion 124 may be wrapped or embedded in a cushion upon which a
passenger may sit. Seat back 125 portion, also formed from bent metal tubes
127,
may likewise be cushioned.
Connecting member 122 is formed having a rectangular cross-sectional
shape 130, although :in other embodiments connecting member 122 may have any
convenient cross-sec tional shape. Tower member 121 has a top end 131 and a
bottom end 132. Bottom end 132 includes a slot 133 shaped to accept connecting
member 122 and a pair of parallel apertures 134 perpendicular to slot 133
through
which rear portion 129 of seat support portion 124 may pass to couple tower
CA 02300027 2000-03-06
8
member 121 to seat frame 123. Tower member 121 lies in the plane defined by
seat back portion 125 with the top end of tower member 121 extending
substantially into seat back portion 125.
Connecting nzember 1.22 has a front end 137 and a rear end 138, and
includes a rear aperture 140 through which rear portion 129 may extend to
mount
connecting member 122 to seat 123. Connecting member 122 is inserted into slot
133 in tower member 121. Iri operation, tower member apertures 134 may be
aligned coincident with connecting member rear aperture 140 enabling rear
metal
tube 129 to be passeci therethrough, coupling tower member 121 and connecting
member 122 to seat support portion 123 and to each other. Connecting member
122 further includes front apesrture 141 through which front portion 128
extends,
mounting connecting member 122 to seat 123. (See FIG. 2c) Alternatively,
connecting member 122 may be affixed to seat support portion 124 by any
convenient fastening means. (See FIG 2d)
In operation, connecting member 122 lies in the plane defined by seat
support portion 124. Both tower member 121 and connecting member 122 may be
embedded in cushioris that sijnultaneously provide passenger comfort and
prevent
restraint system 120 from moving or jiggling. In the embodiment, tower member
121 is pivotally coupled to seat support portion 124. A stop means operable to
limit the movement of tower member 121 is provided by the presence of
connecting member 122 in slot 133, which limits the pivot angle 139 (see FIG.
3c)
through which tower member 121 could be pivoted. While the stop means is
connecting member 122 filling slot 133, any convenient stop means may be used.
It is preferable that ttie pivot angle 139 through which tower member 121 may
pivot is acute. It is niore preferable that the pivot angle 139 be about 17
degrees,
corresponding to the maxirnum allowed deflection of seat back portion 125
caused
by two unbelted passengers striking seat back 125 from behind and two belted
passengers pulling oii tower rnember 121 from the front. Slot 133 preferably
extends through tower member 121 at a slight angle to the normal, such that
when
connecting member 122 engages tower member 121 connecting member 122 may
rest in the horizontal plane of'seat support portion 124 while tower member
121
CA 02300027 2000-03-06
9
remains tilted backwards a few degrees to the vertical. (See FIG. 3c) In this
embodiment, the dirriensions of connecting member 122 and slot 133 are sized
relative to each other such that tower member 121 may rotate forward through a
maximum of 17 degrees. (See FIG. 3c)
Restraint system 120 also includes anchor wing 143 connected to
connecting member 1122. A seat belt anchor 144 is fixedly attached to anchor
wing
143, becoming one point of a three-point restraint. (See FIG. lb) Seat belt
anchor
144 connects lap belt: 145 tenninating in a tongue 146 to seat frame 123.
Alternatively, two seat belt retractors may be attached to both anchor wings
143,
retractably connecting lap belts 145 thereto. Restraint system 120 further
includes
a buckle 147 fixedly attached to seat support portion 124 and adapted to
lockingly
engage tongue 146. Restraint system 120 further includes a pair of guides 148,
such as, a conventional D-loop, attached near the top of tower member 121. A
pair
of torso belt retractors 149 are connected to tower member 121, each housing a
torso belt 150 and becoming the second point of the three-point restraint. The
torso belt 150 is extended upwardly through guide 148 and downwardly across
the
torso of a seated pass-enger. The extending end of torso belt 150 also
connects to
tongue 146. When tongue 146 is locked in buckle 147, buckle 147 becomes the
third point of the three-point restraint. Alternatively, a single belt (not
shown) may
extend between retractor 149 and anchor 144 with a tongue (not shown)
slideably
mounted intermediate thereto.
In operation, the invention adds active passenger restraint protection to the
passive restraint already provided by the deflecting school bus seats. Tower
member 121 does not interfere with the passive restraint function of the seat
back
125, since tower mernber 121 is adapted to pivot forward along with the seat
back
125 in response to ai-ear impact. Seat back portion 125 deflects forward in
response to a forwarci force applied thereto consisting of a passenger located
rearward of the seat back portion 125 impacting seat back portion 125 and/or a
forward force applieci to support tower 121 via torso belt 150 by a seated
passenger
pulling against the torso belt 150.
CA 02300027 2000-03-06
A second alternate embodiment of the present invention is shown in FIGS.
4 through 8. In this embodiment, the restraint system 220 includes a tower
member 221, a connecting member 222, and a crossbar member 252 and is adapted
to be mounted to a seat frame 223. Seat frame 223 includes a seat support
portion
224 connected to a seat back portion 225. Seat frame 223 is also connected to
a
seat leg portion 226 adapted to be affixed to a surface, such as a school bus
floor.
Seat support portion 224 is made of bent metal tubing and includes a front
portion
228. Rod member 229 extends transversely across seat back portion 225
substantially within the plane defined by seat support portion 224. Seat frame
223
10 may be wrapped or embeddeei in cushioning material to provide passenger
comfort.
Harness support assernbly is made up of tower member 221, connecting
member 222, and crossbar members 252, and is mountable to seat frame 223.
When so mounted, tower niejnber 221 lies substantially in the plane defined by
seat back portion 225, and extends through the plane defined by the seat
support
portion 224. Rear er,id 238 of connecting member 222 connects to tower member
221 below the plane defined by seat support portion 224. Front end 237 of
connecting member 222 connects to front portion 228 of seat support portion
224.
In this embodiment, front encl 237 of connecting member 222 features front
aperture 241 (FIG. 6a) through which front portion 228 of seat support portion
224
extends. Tower member 221 is pivotally mounted to seat support portion 224 at
pivot point 253. In order to accommodate two passengers, a pair of harness
assemblies is provided, each with a tower member 221, connecting member 222
and crossbar members 252 and 254.
Rod member 229 extends through tower member 221 and crossbar
members 252 and 254. In the: embodiment, crossbar members 252 includes two
parallel plates lying substantially within the plane of the seat support
portion 224
and extending from the front portion 228 to the rod member 229. Proximal end
255 (FIG. 7) of crossbar members 252 includes substantially circular apertures
265
through which front portion 228 of' seat frame 223 extends. Distal end 256 of
crossbar members 252 includes circular apertures 266 through which rod member
CA 02300027 2000-03-06
11
229 extends at pivot point 253. In this embodiment a crossbar-coupling member
257 (FIG. 8) connects the plates of member 252. Likewise, a second connecting
member 254 is provided consisting of two plates being connected to the second
tower member in the same manner as described for member 252.
Tower member 221 comprises a pair of substantially vertically disposed
members 258 (FIG. :ic), connected by tower coupling member 260. In other
embodiments, tower member 221 may comprise a different number of vertical
members. Likewise, in this embodiment connecting member 222 comprises two
interconnected portions 259 (see FIG. 5c).
Each connecting member 222 includes a slot 270 (see FIG. 4a) at rear end
238. A pin 272 extends through slots 270 with the opposite pin ends fixed to
vertical members 258. The pin slideably connects members 222 to the tower 221.
In normal operation, tower member 221 rests within the plane of the seat back
225,
tilted slightly rearwards with the pin 272 positioned at the forward end 273
(see
FIG. 6a) of the slot 270. As tower member pivots about pivot point 253, pin
272
moves towards the rear of slot 270. Pivoting of tower member 221 is halted
when
pin 272 reaches rear end 274 of slot 270. The length of slot 270 determines
the
maximum angle through which tower member 221 may pivot. In this embodiment,
the length of the slot 270 is such that the maximum angle through which the
tower
member 221 may pivot is 17 degrees.
As in the previous embodiment, restraint system 220 also includes guides
248 connected near the top erid 231 of tower member 221. Seat belt retractors
249
(FIG. 5b) are fixedly attached to the two vertical members of tower 221. Each
seat
belt retractor 249 house a torso belt 250, which connect to a tongue 246 in
turn
connected to lap belt 245. Restraint system 220 also includes a buckle 247
fixedly
attached to seat support portion 224 and adapted to lockingly engage tongue
246.
Torso belt 250 is extended upwardly from torso belt retractor 249 through
guide
248 and downwardly across the torso of a seated passenger while lap belt 245
extends horizontally across the passenger's lap. Alternately, a single belt
(not
shown) may extend between retractor 249 to anchor 244 with a belt tongue
slideably mounted intermediate thereto.
CA 02300027 2000-03-06
12
Many variations are contemplated and included in the present invention. In
addition to those described. in relation to the above embodiments, the present
system contemplates includir-g means for preventing premature forward
deployment of the tower mernber 221 relative to the seatback. For example, the
top end of tower 221 may be connected to seat back portion 225 limiting
relative
motion therebetweer.i until sufficient force breaks the top end of the tower
apart
from the seat back portion.
The preferrecl embodiment of the restraint system is shown in Figs. 9-15.
School bus seat 300 includes a main frame 304 with a pair of front legs 301
and
302 and a pair of rear legs 303. The legs extend upwardly being joined to main
frame 304 having a front niernber 305 integrally joined to a pair of
rearwardly
extending horizontal members 306, 307, and 309. A tubular member 308 has
opposite ends integrally joined to side members 306 and 307 with center member
309 extending between anci integrally joined to front member 305 and
cylindrical
member 308. A pair of flanges 310 and 311 are integrally joined to the
cylindrical
member 308 and the opposite: sides of member 309.
Frame 304 forms the frame for the seat portion of the seat whereas a second
frame 312 forms the frame for the back portion of the seat. Frame 312 includes
a
horizontally extendirig tubular portion 313 integrally joined to a pair of
downwardly extending tubular portions 314 and 315 forming a single frame, in
turn, having bottom ends ititegrally joined to frame 304. Frames 304 and 312
are
located within the cushion respectively of the seat portion and back portion
of the
seat. Tubular portions 314 and 315 are rigid; however, will bend forward as
forward impact pressure is applied to the back portion of the seat forcing the
back
portion of the seat about its bottom end toward the seat portion of the seat.
Upwardly extending towers 316 and 317 are located immediately inward of
frame portions 314 and 315. Tower 316 is mounted to and between plates 355 and
356 (Fig.10) which have holes 380 (Fig. 9) through which tube 308 freely
extends
allowing the tower to pivot on tube 308 in the direction of arrow 322 to and
from
the seat portion of frame 304. Tower 317 is mounted in a similar manner. The
top
ends of towers 316 and 317 are joined together by horizontally extending
member
CA 02300027 2000-03-06
13
323. Flanges 324 and 325 are integrally attached to the top ends of towers 316
and
317 and provide guides through which the webs extend. Wall 339 is fixedly
mounted to frame 312 and member 323 preventing member 323 from moving
behind frame 312. Wall 339 breaks when forward force is applied to either
frame
312 or towers 316/317 allowing independent movement of towers 316/317 relative
to frame 312.
Box constructions 381. and 382 extend between and are fixedly attached to
rear member 308 and front member 305. Each box construction supports a
plurality of stationary bearings and a web retractor. Box construction 381 and
382
include respectively inner plates 328 and 329 having rear ends integrally
secured to
member 308 and frorit ends fixedly secured to member 305. Likewise, box
constructions 381 anci 382 have outwardly located members, respectively 330
and
331 integrally secured and extending between members 308 and 305. Retractor
plates 326 and 327 are secured respectively to members 328 and 330 and members
329 and 331. Two conventional inertia locking retractors are respectively
mounted
to and beneath plates 326 and 327 with the web of each retractor extending
rearwardly toward tubular member 308.
Each box construction, 381 and 382 have three stationary bearings with
their opposite ends fixedly attached to the inner member and outer member of
each
box construction. For example, bearings 332, 333 and 334 (Fig. 10) have first
ends
fixedly attached to inner men.iber 328 and second ends fixedly attached to
outer
member 330. Retractor 335 (Fig. 11) is fixedly attached to and beneath plate
326
and has web 336 extending rearwardly over stationary bearings 332-334 but
beneath movable bearings 337 and 338. Web 336 continues around tubular
member 308 extending upwardly behind tower 316 to the top of the tower. The
web then extends over a bearing surface at the top of the tower and freely
through
a loop, such as flange 324 (Fig. 9) with the distal end 340 of web 336 being
fixedly
attached to the rear corner 341 of frame 304.
A conventional seat belt buckle tongue 342 is slidably mounted to web 336
and is lockingly engagable with a conventional seat belt buckle 343, in turn,
attached by web 344 to flange 310. Thus, with web 344 extending upward through
CA 02300027 2000-03-06
14
the seat cushion, tongue 342 may lockingly engage buckle 343 forcing the web
across the shoulder and chest of the occupant residing on the seat and then
across
the lap of the occupant. Web 336 therefore includes a chest portion 384 and a
lap
portion 385 when thE: tongue is secured to the buckle. Web 336 extends outward
of the cushion formi ng the back portion of the seat. An identical retractor
web
combination is provided on the right side of the seat as viewed in Fig. 9
relative to
tower 317 and box construction 382.
When force is applied in a forward direction to the rear of the seat by a
passenger located behind seat 300, frame portions 314 and 315 are pushed
forward
bending and pivoting about their bottom ends. Frame portions 314 and 315 are
sufficiently rigid to hold the seat back portion in an upright position but
sufficiently weak to bend when rearward force is applied thereto thereby being
in
compliance with the safety standards set by the National Highway Traffic
Safety
Administration as discussed i.n the Description of the Prior Art herein. If a
seat
300 is occupied then the forward motion of the passenger on seat 300 will
apply
forward force via web 336 to tower 316 rupturing breakable wall 339 allowing
the
tower to pivot independent of frame 312. Towers 316 and 317 are pivotally
mounted to tube 308 thereby allowing the towers to pivot forward towards the
seat
portion or frame 304 of the seat. A pair of stop flanges 350 and 351 are
fixedly
attached respectively to towers 316 and 317 and project forwardly of the
towers.
The stop flanges are designeci to allow only a limited amount of forward
pivotal
motion of the towers. Once the stop flanges contact members 330 and 331,
additional forward p ivotal motion of the towers and frame 312 is prevented.
Stop flange 350 will riow be described it being understood that a similar
description applies to stop flange 351. Stop flange 350 includes a pair of
spaced
apart walls 355 and 356 (Fig. 10) fixedly secured to the opposite sides of the
bottom of tower 316. A wall 357 has opposite ends fixedly attached to walls
355
and 356 and extends therebetween. Wall 357 is elevated and spaced apart from
the
top surface of member 330 when the tower is in the erect or normal position.
Wall
357 is spaced apart from the top surface of member 330 to only allow a
predetermined amount of forward pivotal motion of the tower until the wall
CA 02300027 2000-03-06
contacts the top surface of member 330 thereby preventing further pivotal
motion
of the tower and frarne 312. The amount of forward pivotal motion of the tower
is
designed to be in accordance with the deflection requirements of the National
Highway Traffic Safety Administration specifications as previously discussed.
A web slack take-up device is mounted within each box constructions 381
and 382. The web slack take-up device 360 (Fig. 13) positioned within box
construction 381 will now be described it being understood that a similar
description applies to the web slack take-up device positioned within box
construction 382. Device 360 includes a bottom wal1361 secured to a pair of
10 upwardly extending side walls 362 and 363 between which are fixedly mounted
a
pair of bearings 337 and 338. Web 336 extends between bearings 337 and 338 and
the three stationary bearings :332-334 (Fig. 11). The proximal ends of walls
362
and 363 are fixedly attached to sleeve 318 and are designed to pivot around
tube
308. Tube 308 exterids freely through sleeve 318 (Fig. 9) and sleeve 319 of
the
slack take up device mounted within box construction 382. Walls 362 and 363
have cut out portions 386 anct 387 (Fig. 11) preventing interference of walls
362
and 363 with stationary bearings 333 and 332 when the tower is in the erect
position.
Towers 316 and 317 cause the slack take-up devices to pivot downwardly
as the towers pivot toward the seat portion of the seat; however, pivotal
movement
of the towers in an opposite clirection away from the seat portion does not
cause the
slack take-up devices to pivot to their original positions. Each tower
includes a
projection contactable with a projection extending outwardly from sleeves 318
and
319. For example, tower 316 includes projection 370 (Fig. 14) extending
inwardly
whereas sleeve 318 includes projection 371 extending outwardly toward tower
316. Thus, when tower 316 pivots in a counter clockwise direction, as viewed
in
Fig. 14, projection 370 contacts projection 371 causing sleeve 318 and
bearings
337 and 338 to pivot therewith in a counter clockwise direction removing slack
from the web. Movement of tower 316 in a clockwise direction simply moves
projection 370 apart from projection 371 without moving sleeve 318.
CA 02300027 2000-03-06
16
In operation, apon the occurrence of a crash, forward force may or may not
be applied to the rear of the seat by the passenger located behind the seat.
Forward
force is applied however to web 336 by the occupant resting upon seat 300.
With
retractor 335 locked as the result of sensed deacceleration, forward force is
applied
via the web to towers 316 and 317 causing the towers to pivot forwardly toward
the seat portion of the seat. Stops 350 and 351 of towers 316 and 317 limit
the
forward pivotal motion of the towers. Simultaneously, the web slack take-up
devices within each box construction 381 and 382 pivot downward resulting in
bearings 337 and 338 of each web slack take-up device contacting the
respective
web of each retractor forcing the webs into a serpentine path as depicted in
Fig. 12
thereby removing any slack fi-om the webs. Even if an occupant is not resting
upon seat 300, impact of a passenger behind seat 300 upon the back portion of
seat
300 will cause frame 312 to bend and pivot toward the seat portion of the seat
to
the maximum angle permitted by stops 350 and 351.
Fig. 15 illustrates seat 300 which has a seat cushion or other enclosure 386
enclosing frame 304, a cushion or other enclosure 383 enclosing frame 312 and
a
center cushion or other enclosure 384 enclosing towers 316 and 317 along with
member 323. Slots 385 are provided in cushion 384 for the webs to extend
through. Cushion 383 is indented to receive cushion 384 to allow the center
cushion 384 to pivot forward independent of outer cushion 383 when force is
applied to towers 316 and 317 by occupant force being applied to the webs.
Many advantages flow from use of the preferred embodiment of the
invention. For example, webbing from a restrained occupant on seat 300
simultaneously applies load to towers 316 and 317 causing the towers to pivot
forward while applyi;ng tension load to the entire webbing length. That is,
slack is
removed from the webbing surrounding the occupant by the downwardly pivoting
slack take up devices. Tension of the restraint is therefore increased around
the
occupant. A large mechanical advantage is provided by the lengths of the
towers
which exceed the length of the slack take up devices. As the towers pivot
downwardly along with bearings 337 and 338, the tension increases
proportionately thereby decreasing the occupant forward acceleration rate
CA 02300027 2000-03-06
17
proportionally. The increasing tension in the lap portion of the web centers
the
occupant in proper seating position during forward impact movement. Likewise,
additional tension in the web controls kinematic motion of the restrained
occupant
so that the motion is straight during forward motion and straight during
rebound
motion. The added tension iri the web will further cause the occupant to be in
proper seating position after the occupant motion is complete.
The system of Fig. 9 will not cause additional stiffness to the seat back
when the occupant is unrestrained or the seat is unoccupied and thus,
maintains the
energy management capability for any unrestrained occupant located behind seat
300. The system preserves the under seat clearance for other vehicle features.
Likewise, the system will not require additional structure to the seat back
when the
restrained or unrestrained occupant is forced rearward into the seat back
during
impact.
While the invention has been illustrated and described in detail in the
drawings and foregoing description, the same is to be considered as
illustrative and
not restrictive in character, it being understood that only the embodiments
have
been shown and described and that all changes and modifications that come
within
the spirit of the inverition are desired to be protected.
