Passive safety belt system

A safety belt system has an elongated flexible drive element or tape which pulls a carrier connected with the safety belt along a track. Opposite ends of the tape are connected to a dual channel spool having inner and outer spool portions. A single reversible electric motor is operable to rotate the dual channel spool in one direction to pull the safety belt away from the occupant of a vehicle and in the opposite direction to pull the safety belt toward the occupant of the vehicle. As the spool is rotated in one direction, the tape is wound around one of the spool portions to pull the carrier rearwardly along the track. When the spool is rotated in the opposite direction, the tape is wound around the other spool portion to pull the carrier forwardly along the track.

BACKGROUND OF THE INVENTION 
The present invention relates to a passive safety belt system in which a 
safety belt is moved toward and away from an occupant of a vehicle. 
A known passive safety belt system includes a track which lies above the 
door of a vehicle. A carrier is connected with a safety belt and moves in 
opposite directions along the track. When the carrier is moved in a 
rearward direction along the track, the safety belt is moved toward the 
occupant of the vehicle to position the safety belt to restrain movement 
of the occupant in the event of an accident. When an occupant is to exit 
the vehicle, the carrier is moved forwardly along the track to move the 
safety belt away from the occupant to facilitate exiting from the vehicle. 
Known passive seat belt systems of this type are disclosed in U.S. Pat. 
Nos. 4,061,365, issued Dec. 6, 1977, and entitled "Safety System for 
Protection of Automotive Seat Occupant"; 4,313,622, issued Feb. 2, 1982 
and entitled "Passive Seatbelt System"; and 4,475,745, issued Oct. 9, 1984 
and entitled "Seat Belt Drive Device". 
Since a passive safety belt system is mounted in the passenger compartment 
of a vehicle, it is important that the safety belt system be compact. Even 
more importantly, the apparatus for moving a safety belt toward and away 
from the occupant of the vehicle must be durable and capable of moving a 
carrier back and forth along a track through many cycles of operation. Due 
to commercial considerations, the cost of a passive safety belt system 
which meets these requirements should be as low as possible. 
SUMMARY OF THE INVENTION 
The present invention provides a relatively compact and durable passive 
safety belt system which is operable to pull a safety belt toward and away 
from an occupant of a vehicle. During operation of the safety belt system, 
an elongated flexible drive element or tape pulls a carrier in opposite 
directions along a track. One end of the tape is connected to a first 
spool mechanism. The other end of the tape is connected with a second 
spool mechanism. A motor is operable to rotate the spool mechanisms to 
wind the tape on one spool mechanism and unwind the tape from the other 
spool mechanism. 
In a preferred embodiment, the two spool mechanisms are rotatable together 
about a common axis by a single reversible drive motor. The two spool 
mechanisms are portions of a one-piece, dual channel drum or spool. When 
the seat belt is in one of its extreme positions, a relatively large 
number of turns of tape are on the spool portion from which tape is to be 
unwound in moving the seat belt to its other extreme position, whereas a 
relatively small number of turns of tape are on the spool portion upon 
which the tape is to be wound in moving the seat belt to its other extreme 
position. As the spool portions are rotated, excess tape fed from the 
spool portion having the relatively large number of turns is temporarily 
stored adjacent the spool portion and along the track until it is wound on 
the other spool portion.

DESCRIPTION OF ONE EMBODIMENT OF THE INVENTION 
A passive safety belt system 10 (FIG. 1) is mounted adjacent to the door 12 
of a vehicle and is operable to move a safety belt 14 toward and away from 
a person in a driver's seat 16. The passive safety belt system 10 includes 
a track 18 which overlies the door 12 of the vehicle and is mounted on the 
body of the vehicle. A carrier 22 is connected with the safety belt 14 and 
is movable forwardly and rearwardly along the track 18. The track 18 is 
formed of a light weight, wear resistant metal, such as aluminum. The 
carrier 22 is pulled along the track 18 between a forward position, shown 
in solid lines in FIG. 1, and a rearward position adjacent a person in the 
driver's seat 16 by operation of a drive assembly 24. Because the length 
of the safety belt 14 required to restrain the driver in the seat 16 is 
less than the length required when the safety belt and carrier are in the 
forward position illustrated in FIG. 1, the excess length of safety belt 
14 is withdrawn into a seat belt retractor 40 as the carrier 22 moves 
rearwardly. 
When a driver gets into the vehicle, the carrier 22 is in the forward 
position illustrated in FIG. 1 and the safety belt 14 is located away from 
the seat 16 to facilitate entry of the driver. After the driver has shut 
the door 12 and turned a key in the ignition, a signal is transmitted over 
a lead 32 to a control unit 34. Upon receiving this signal, the control 
unit 34 energizes the drive assembly 24 with current conducted over a lead 
36. Operation of the drive assembly 24 moves the carrier 22 rearwardly 
along the track 18 from the forward position toward the rearward position. 
When the carrier 22 reaches the rearward position, the carrier actuates a 
limit switch 42. Actuation of the limit switch 42 signals the control unit 
34 that the safety belt 14 has been properly positioned relative to the 
driver. Upon receiving this signal, the control unit 34 terminates 
operation of the drive assembly 24. 
When the vehicle has stopped and the ignition is turned off, a signal is 
conducted over the lead 32 to the control unit 34. Upon receiving this 
signal, the control unit 34 energizes the drive assembly 24 to move the 
carrier 22 along the track 18 from the rearward position to the forward 
position. As the carrier 22 moves forwardly along the track 18, the safety 
belt is pulled away from the driver of the vehicle. When the carrier 22 
reaches the forward position, indicated in solid lines in FIG. 1, a limit 
switch 44 is actuated to signal the control unit 34 to interrupt operation 
of the drive assembly 24. At this time, the safety belt 14 is pulled 
forwardly of the driver to facilitate exiting from the vehicle. 
In accordance with the present invention, the drive assembly 24 (FIG. 2) is 
relatively compact, light weight and easily mounted in a vehicle. The 
drive assembly 24 includes a spool assembly 50, a reversible electric 
motor 52 and an elongated flexible drive element or tape 54. The flexible 
drive element extends from the spool assembly 50 through a first track 
section 56 formed of a polymeric material, around a pulley 57 at the 
forward end of the track 18, through the track 18, and through a second 
track section 58 formed of a polymeric material, to the spool assembly 50. 
The flexible drive element is suitably fixed to the carrier 22. The track 
section 56 lies adjacent the track section 58 and the carrier track 18. 
The spool assembly 50 is driven by the reversible electric motor 52 to 
pull the tape 54 around the pulley 57 and move the carrier 22 (FIG. 1) 
either forwardly or rearwardly along the track 18. 
The tape 54 is a single piece of woven polymeric webbing material and has a 
width of approximately 5/16 of an inch and a thickness of approximately 
1/16 of an inch. It should be understood that the foregoing dimensions of 
the tape 54 have merely been set forth for purposes of clarity of 
description and that tapes having different dimensions could be used if 
desired. The length of tape which is extended and retracted by the spool 
assembly 50 to move the carrier 22 is determined by the distance between 
the forward and rearward positions of the carrier 22. Elongated flexible 
drive elements other than a tape could be connected with the spool 
assembly 50 and carrier 22 if desired. However, the compact construction 
of the spool assembly 50 is facilitated by having the elongated flexible 
drive element 54 formed of a thin tape so that a relatively long length of 
the tape can be wound in a small space. 
The spool assembly 50 includes a housing 60 (FIG. 3) which encloses a dual 
channel spool 62. The housing 60 includes a one-piece metal base or 
mounting plate 64 upon which the dual channel spool 62 is mounted for 
rotation about an axis 66 (FIG. 3). A one-piece cover 68 of polymeric 
material cooperates with the mounting plate 64 to enclose the dual channel 
spool 62. The one-piece cover 68 has a neck portion 72 (FIGS. 2 and 4) 
which is connected to the polymeric track sections 56 and 58. The neck 
portion 72 of the cover 68 (FIG. 4) forms channels which receive the track 
sections 56 and 58. A one-piece metal cover plate 80 overlies the cover 68 
and is connected to the base 64 by fasteners 82. The metal cover plate 80 
holds the cover 68 in place on the base 64. In addition, the cover plate 
80 protects and reinforces the cover 68. 
The dual channel spool or drum 62 (FIGS. 3 and 5-7) is formed as one piece 
and includes an axially outer spool portion 86 and a coaxial inner spool 
portion 88. The outer spool portion 86 includes an annular tape receiving 
outer channel 92. The inner spool portion 88 includes an annular tape 
receiving inner channel 94. The coaxial inner and outer channels 92 and 94 
are separated from each other by an annular intermediate flange 98. An 
annular base flange 100 is disposed in a coaxial relationship with the 
intermediate flange 98 and cooperates with the intermediate flange to form 
the inner channel 94. Although the outer channel 92 is formed between the 
intermediate flange 98 and the cover 68, an outer flange could be provided 
on the dual channel spool 62 to cooperate with the intermediate flange 98 
and form the channel 92. The flanges 98 and 100 project radially outwardly 
from and are formed as one piece with a generally cylindrical base 104. 
The dual channel spool 62 is supported for rotation about the axis 66 (FIG. 
3) by a metal sleeve 132. The sleeve 132 is fixed to the polymeric 
material of the dual channel spool 62 and is rotatable relative to a 
stationary axle 134. The axle 134 is fixed to the mounting plate 64 and 
has a central axis which is coincident with the axis 66 and which extends 
perpendicular to the central axis of the worm 120. Although the coaxial 
relationship of the spool portions 86 and 88 is preferred because it 
contributes to the compactness of the drive assembly 24, the spool 
portions could be mounted for rotation about separate axes if desired. 
The dual channel spool 62 has a generally cylindrical drive section 116 
which is disposed in a coaxial relationship with spool portions 86 and 88. 
The drive section 116 has external gear teeth 118 which engage a worm 120 
(FIG. 3). The worm 120 is rotatably mounted on the mounting plate 64 and 
is driven by the reversible electric motor 52. 
When the worm 120 is rotated by the motor 52, the dual channel spool 62 is 
rotated in either one of two directions about the axis 66 to wind the tape 
54 onto one of the spool portions 86 or 88 and to unwind the tape from the 
other spool portion. Although it is preferred to form the dual channel 
spool 62 as one piece, the spool could be formed as a plurality of 
separate pieces. For example, the spool portion 86 could be separate from 
the spool portion 88. If this was done, a separate motor could be provided 
to drive each spool portion. 
Retainer slots 122 and 124 (FIGS. 5 and 6) are formed in diametrically 
opposite sides of the dual channel spool 62. The retainer slot 122 is 
formed in the outer spool portion 86 and opens to the channel 92 to engage 
the end of the tape section 54b (FIG. 7). The retainer slot 124 is formed 
in the inner spool portion 88 and opens to the channel 94 to engage the 
end of the tape section 54a. Thus, opposite ends of the one-piece tape 54 
are connected to the dual channel spool 62. 
The tape 54 is wound in opposite directions on the inner and outer spool 
portions 86 and 88 (FIGS. 3 and 7). The tape section 54b is wound in 
layers which extend in a counterclockwise direction (as viewed in FIG. 7) 
from the retainer slot 122. The tape section 54a is wound in the opposite 
direction from the retainer slot 124. Therefore, when the dual channel 
spool 62 is rotated about its central axis 66, the tape 54 is unwound from 
one of the spool portions 86 or 88 and is wound onto the other spool 
portion. 
When the motor 52 is operated in one direction, the spool assembly 50 
extends an upper (as viewed in FIG. 2) section 54a of the one-piece tape 
54 and retracts a lower (as viewed in FIG. 2) section 54b of the tape. 
This pulls the carrier 22 rearwardly along the track 18 from the forward 
position illustrated in solid lines in FIG. 1 to the rearward position 
illustrated in dashed lines in FIG. 1. Similarly, when the motor 52 is 
operated in the opposite direction, the spool assembly 50 extends the 
lower section 54b of the tape and retracts the upper section 54a of the 
tape. This pulls the carrier 22 forwardly along the track 18 from the 
rearward position to the forward position. 
When the carrier 22 is in the forward position shown in solid lines in FIG. 
1, the tape 54 is wound on the inner spool portion 88 (FIG. 3) and there 
is only a single turn of the tape around the outer spool portion 86. When 
the motor 52 (FIG. 2) is energized to drive the worm 120 (FIG. 3) to 
rotate the dual channel spool 62 in a clockwise direction, as indicated by 
the arrow 126 in FIG. 7, the upper section 54a of tape is unwound from the 
spool portion 88 in the manner indicated by the arrow 128. At the same 
time, the lower tape section 54b is wound onto the outer spool section 86, 
in the manner indicated by the arrow 130 in FIG. 7. Rotation of the dual 
channel spool 62 is continued until the carrier 22 has been pulled to the 
rearward position shown in dashed lines in FIG. 1. The tape 54 will then 
be almost completely unwound from the inner spool portion 88. 
When the carrier 22 is to be pulled from the rearward position back to the 
forward position, the motor 52 is energized to drive the worm 120 and 
rotate the dual channel spool 62 in a counterclockwise direction, that is, 
in a direction opposite to the arrow 126 in FIG. 7. As this occurs, the 
tape section 54a is wound onto the spool portion 88. Simultaneously, the 
lower tape section 54b is unwound from the spool portion 86. 
When a driver enters a vehicle through the door 12, the carrier 22 will be 
in the forward position shown in FIG. 1. At this time, the upper section 
54a of the tape 54 will be wound on the spool portion 88 in the manner 
shown in FIG. 3. The tape will be almost completely unwound from the spool 
portion 86. 
After the driver has closed the door 12 and actuated the ignition, the 
control unit 34 will energize the motor 52 to drive the worm 120. The worm 
120 will rotate the dual channel spool 62 about its central axis 66 to 
unwind the tape 54a from the spool portion 88 and to begin winding the 
tape on the spool portion 86. As this happens, the carrier 22 is pulled 
along the track 18 by the section 54b of the tape. 
Upon initiation of rotation of the dual channel spool 62, there are a 
relatively large number of turns of the tape 54 wrapped around the spool 
portion 88. Therefore, an outer layer of tape wrapped around the spool 
portion 88 has a substantially greater diameter and circumferential length 
than the layer of tape wrapped around the spool portion 86. As the worm 
120 turns the dual channel spool 62 through one revolution in the 
direction indicated by the arrow 126 in FIG. 7, a longer length of tape 
will be unwound from the spool portion 88 than will be wound onto the 
spool portion 86. This is because the outer layer or turn of tape around 
the spool portion 88 has a larger diameter than the layer of tape which is 
wound around the spool portion 86 during the first revolution of the dual 
channel spool 62. 
In order to eliminate the need for a spring loaded take-up pulley, there is 
sufficient clearance between the inner side surfaces 56a, 56b (see FIG. 4) 
of the track section 56 and the tape 54 to allow the tape to deflect 
relative to the track section 56. This enables excess tape unwound from 
the inner spool portion 88 to be stored along the track section 56. Also, 
a certain amount of excessive tape can be stored in the cover 68. Further, 
clearance is also provided between the track 18 and the tape 54 for this 
purpose. Specifically, upon initiation of unwinding of the tape 54 from 
the spool portion 88 of the dual channel spool 62, the portion of the tape 
in track section 56 will have a longitudinal central axis with a 
configuration which corresponds to the configuration of the longitudinal 
axis of the track section 56. As the dual channel spool 62 is rotated and 
the rate at which the tape is unwound from the spool portion 88 exceeds 
the rate at which tape is wound onto the spool portion 86, the section 54a 
of tape disposed between the spool portion 88 and the carrier 22 deflects 
relative to the track section 56 and track 18. As the section 54a of the 
tape deflects, the length of tape between the carrier 22 and spool portion 
88 increases. The respective clearances between the tape 54 and track 
section 56 and track 18 are such to accommodate this deflection of the 
tape 54. 
As the carrier 22 is pulled along the track 18 from the forward position 
toward the rearward position, the number of turns on the spool portion 88 
decreases and the number of turns on the spool portion 86 increases. As 
this occurs, the rate of winding of the tape on the spool portion 86 
increases and the rate of unwinding of the tape from the spool portion 88 
decreases. When the number of turns of tape on the spool portion 86 is 
equal to the number of turns of tape on the spool portion 88, the rate of 
unwinding of tape from the spool portion 88 will be the same as the rate 
at which tape is wound onto the outer spool portion 86. The length of 
excess tape stored in the track between the spool portion 88 and the 
carrier 22 will then be at a maximum. Therefore, when there are equal 
numbers of turns of tape 54 on the spool portions 86 and 88, there is a 
maximum amount of deflection of the tape relative to the track section 56 
and track 18. 
Continued rotation of the dual channel spool 62 results in the rate of 
winding of tape on the spool portion 86 exceeding the rate of unwinding of 
tape from the spool portion 88. As this occurs, the amount of excess tape 
stored along the track section 56 and track 18 is diminished. When the 
carrier 22 reaches the rearward position shown in dashed lines in FIG. 1, 
all of the excess tape will have been removed and wound onto the outer 
spool portion 86. The configuration of the longitudinal central axis of 
the tape 54 will then correspond to the configuration of the longitudinal 
central axis of the track sections 56, 58 and track 18. 
When the driver of the vehicle turns off the ignition and removes the key, 
the control unit 34 will cause the motor 52 to reverse the direction of 
rotation of the dual channel spool 62. As this occurs, the tape 54 will be 
unwound from the spool portion 86 and wound onto the spool portion 88. 
Since the diameter of the outer layer of tape 54 on the spool portion 86 
is greater than the diameter of the outer layer of tape on the spool 
portion 88, the rate at which tape is unwound from the spool portion 86 
will be greater than the rate at which tape is wound onto the spool 
portion 88. The excess length of tape 54 will be stored in the track 
section 58, track 18 between the carrier 22 and the spool portion 86, and 
in the cover 68. Thus, the lower section 54b of the tape will be deflected 
relative to the track section 58 and track 18. 
When the diameter of the layers of tape wound around the spool portion 88 
is equal to the diameter of the layer of tape wound around the spool 
portion 86, the rate at which tape is fed from the spool portion 86 to 
spool portion 88 will be equal. Continued rotation of the dual channel 
spool will result in the tape 54 being wound onto the spool portion 88 at 
a greater rate than it is unwound from the spool portion 86. As this is 
occurring, the excess tape stored along the rack section 58 and track 18 
is diminished. When the carrier 22 reaches the forward position shown in 
solid lines in FIG. 1, the configuration of the longitudinal central axis 
of the tape 54 will correspond to the configuration of the longitudinal 
central axis of the track sections 56, 58 and track 18. 
In view of the foregoing description, it is apparent that the present 
invention provides a relatively compact and durable passive safety belt 
system 10 which is operable to move a safety belt 14 toward and away from 
an occupant of a vehicle. During operation of the safety belt system 10, 
an elongated flexible drive element or tape 54 pulls the carrier 22 either 
rearwardly or forwardly along the track 18 to move the safety belt 14 
either toward or away from the occupant of the vehicle 
Although the foregoing description of the passive safety belt system 10 has 
been in conjunction with the driver of a vehicle, it should be understood 
that the passive safety belt system could be used in conjunction with a 
passenger of the vehicle. Further, from the above description of a 
preferred embodiment of the present invention, those skilled in the art 
will perceive improvements, changes and modifications therein. Such 
improvements, changes and modifications are intended to be covered by the 
appended claims.