U.S. patent application number 09/817524 was filed with the patent office on 2003-04-17 for parallelogram load sensing apparatus for a seat belt webbing.
This patent application is currently assigned to TRW Inc.. Invention is credited to Fullerton, Michael G., Wolfe, George B..
Application Number | 20030070846 09/817524 |
Document ID | / |
Family ID | 25223265 |
Filed Date | 2003-04-17 |
United States Patent
Application |
20030070846 |
Kind Code |
A1 |
Wolfe, George B. ; et
al. |
April 17, 2003 |
Parallelogram load sensing apparatus for a seat belt webbing
Abstract
An apparatus (210) includes seat belt webbing (12), a
parallelogram linkage (220), a sensor lever (370), and a sensor
(379). The seat belt webbing (12) helps to protect the occupant
(14) of the vehicle (18). The parallelogram linkage (220) includes
a first beam (352) and a second beam (362) parallel to the first
beam (352). The first and second beams (352, 362) each bend in
response to at least part of a load applied by the seat belt
webbing (12). The sensor lever (370) is interposed between the
first and second beams (352). The sensor lever (370) has a
connection with the first and second beams (352). The connection
causes the sensor lever (370) to deflect upon bending of the first
and second beams (352). The sensor (379) senses the deflection of
the sensor lever (370) and provides an output signal indicative of
the amount bending of the first and second beams (352, 362).
Inventors: |
Wolfe, George B.; (Plymouth,
MI) ; Fullerton, Michael G.; (Ypsilanti, MI) |
Correspondence
Address: |
TAROLLI, SUNDHEIM, COVELL, TUMMINO & SZABO L.L.P.
1111 LEADER BLDG.
526 SUPERIOR AVENUE
CLEVELAND
OH
44114-1400
US
|
Assignee: |
TRW Inc.
|
Family ID: |
25223265 |
Appl. No.: |
09/817524 |
Filed: |
March 26, 2001 |
Current U.S.
Class: |
177/144 ;
180/273 |
Current CPC
Class: |
G01G 19/4142 20130101;
B60R 21/0155 20141001; G01G 23/005 20130101; B60R 21/01516
20141001; B60R 21/01556 20141001; B60R 22/18 20130101 |
Class at
Publication: |
177/144 ;
180/273 |
International
Class: |
B60T 007/14; G01G
019/52 |
Claims
Having described the invention, the following is claimed:
1. An apparatus comprising: seat belt webbing for helping to
protect an occupant of a vehicle; a first parallelogram linkage
including a first beam and a second beam parallel to said first
beam, said first and second beams each bending in response to at
least part of a load applied by said seat belt webbing; a first
sensor lever interposed between said first and second beams, said
first sensor lever having a connection with said first and second
beams, said connection causing said first sensor lever to deflect
upon bending of said first and second beams; and a first sensor for
sensing the deflection of said first sensor lever and providing a
first output signal indicative of the amount bending of said first
and second beams.
2. The apparatus as defined in claim 1 wherein said first and
second beams each have adjacent interconnected first ends which
receive at least part of the load from said seat belt webbing, said
first and second beams each further having adjacent interconnected
second ends, said second ends transmitting the part of the load to
the vehicle.
3. The apparatus as defined in claim 2 further including a fastener
assembly for securing said apparatus to the vehicle.
4. The apparatus as defined in claim 1 wherein said first sensor
receives part of the load applied by said seat belt webbing, the
output signal being combined with another output signal indicative
of another part of the load applied by said seat belt webbing to
produce an angle value indicative of the direction in which the
load is applied by said seat belt webbing.
5. The apparatus as defined in claim 1 further including a second
parallelogram linkage for sensing another part of the load applied
by said seat belt webbing.
6. The apparatus as defined in claim 5 wherein said second
parallelogram linkage comprises: a third beam and a fourth beam
parallel to said third beam, said third and fourth beams each
bending in response to the other part of the load applied by said
seat belt webbing; a second sensor lever interposed between said
third and fourth beams, said second sensor lever deflecting upon
bending of said third and fourth beams; and a second sensor for
sensing the deflection of said second sensor lever and providing a
second output signal indicative of the amount of bending of said
third and fourth beams, the second output signal being combined
with the first output signal to produce an angle value indicative
of the direction in which the load is applied to said apparatus by
said seat belt webbing and a tension value indicative of the
magnitude of the vertical component of force applied to said
apparatus by said seat belt webbing.
7. The apparatus as defined in claim 6 wherein said third and
fourth beams each have adjacent interconnected first ends which
receive the other part of the load from said seat belt webbing,
said third and fourth beams each further having adjacent
interconnected second ends, said second ends transmitting the other
part of the load to the vehicle.
8. The apparatus as defined in claim 7 wherein said seconds ends of
said first and second beams are adjacently interconnected with said
second ends of said third and fourth beams.
9. The apparatus as defined in claim 1 wherein said first sensor
lever includes a first curved surface engaging a lower surface of
said first beam and a second curved surface engaging an upper
surface of said second beam.
10. The apparatus as defined in claim 9 wherein said first and
second curved surfaces allow pivoting of one end portion of said
first sensor lever as said first sensor lever is deflected by at
least one of said first and second beams.
11. The apparatus as defined in claim 1 further including a plate
member with a surface defining a travel stop, said surface limiting
movement of said first ends of said first and second beams as said
first and second beams bend.
12. The apparatus as defined in claim 11 further including a
housing for restricting said first ends of said first and second
beams from pivoting relative to said housing.
13. The apparatus as defined in claim 1 wherein said first sensor
lever has a longitudinal axis, said first beam and said second beam
each being disposed equidistantly from said longitudinal axis when
said first and second beams are in an unloaded condition.
14. An apparatus comprising: seat belt webbing for helping to
protect an occupant of a vehicle; and a dual parallelogram linkage,
said dual parallelogram linkage comprising: a first beam and a
second beam parallel to said first beam, said first and second
beams each having adjacent interconnected first ends which receive
a first component of a load from said seat belt webbing, said first
and second beams each having adjacent interconnected second ends
which receive a second component of the load from said seat belt
webbing, said first and second beams each further having adjacent
interconnected middle portions, said middle portions transmitting
the first and second components of the load to the vehicle, said
first and second beams each bending in response to the load from
said seat belt webbing; a sensor lever interposed between said
first and second beams, said sensor lever having a first connection
with said first and second beams, said sensor lever further having
a second connection with said first and second beams, said first
connection causing a first part of said sensor lever to deflect
upon bending of said first and second beams, said second connection
causing a second part of said sensor lever to deflect upon bending
of said first and second beams; a first sensor for sensing the
deflection of said first part of said sensor lever and providing a
first output signal indicative of the amount bending of said first
and second beams by the first component of the load; and a second
sensor for sensing the deflection of said second part of said
sensor lever and providing a second output signal indicative of the
amount bending of said first and second beams by the second
component of the load.
Description
TECHNICAL FIELD
[0001] The present invention relates to an apparatus for sensing a
load, and more particularly, to an apparatus for sensing a load
applied by vehicle seat belt webbing.
BACKGROUND OF THE INVENTION
[0002] A conventional vehicle seat belt system restrains an
occupant of a vehicle seat. The system includes seat belt webbing
anchored to the floor pan of the vehicle, a tongue on the webbing,
a seat belt buckle for receiving the tongue, and an apparatus for
sensing the tension placed on the seat belt webbing by the
occupant. An occupant weight sensor may be associated with the
vehicle seat. The weight sensor provides an output signal that
indicates a sensed weight of the occupant of the seat. An
inflatable vehicle occupant protection device, such as an air bag,
is inflated under the control of the weight sensor.
[0003] When the vehicle experiences a collision, a source of
inflation fluid is actuated by a controller and directs inflation
fluid into the inflatable vehicle occupant protection device. The
controller receives an output signal from the weight sensor and
controls the amount of inflation fluid directed into the inflatable
vehicle occupant protection device in response to the output signal
from the weight sensor. If the weight sensed by the weight sensor
is below a predetermined amount (i.e., a low weight in the seat or
no occupant in the seat), then the controller disables the source
of inflation fluid to prevent inflation of the inflatable vehicle
occupant protection device. The controller thus controls the fluid
pressure in the inflatable vehicle occupant protection device and
the restraining force provided by the inflatable vehicle occupant
protection device based on the sensed weight of the occupant. The
controller may also disable the inflatable vehicle occupant
protection device.
[0004] The seat belt webbing, when buckled about an occupant, may
be placed under tension. In this case, the weight sensor may not
sense an accurate weight of the occupant. The seat belt tension
sensing apparatus can produce an output signal that can be combined
with the output signal from the weight sensor by the controller so
that a more accurate weight value for the vehicle occupant is
produced.
[0005] An apparatus that can determine the vertical component of
the tension on the seat belt webbing and the angle at which that
tension is applied can be utilized by the controller to more
accurately determine the weight of the vehicle occupant. Also, such
apparatus may determine the type of object in the vehicle seat,
such as a child seat.
SUMMARY OF THE INVENTION
[0006] The present invention relates to an apparatus that includes
seat belt webbing, a parallelogram linkage, a sensor lever, and a
sensor. The seat belt webbing helps to protect the occupant of the
vehicle. The parallelogram linkage includes a first beam and a
second beam parallel to the first beam. The first and second beams
each bend in response to a load applied by the seat belt webbing.
The sensor lever is interposed between the first and second beams.
The sensor lever has a connection with the first and second beams
that causes the sensor lever to deflect upon bending of the first
and second beams. The sensor senses the deflection of the sensor
lever and provides an output signal indicative of the amount
bending of the first and second beams and, therefore, the amount of
load applied by the seat belt webbing.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] The foregoing and other features of the invention will
become more apparent to one skilled in the art upon consideration
of the following description of the invention and the accompanying
drawings, in which:
[0008] FIG. 1 is a schematic view of a seat belt system including
an apparatus embodying the present invention;
[0009] FIG. 2 is a schematic isometric view of the apparatus of
FIG. 1 that is part of the seat belt system;
[0010] FIG. 3 is a schematic view of the apparatus of FIG. 2 under
an unloaded condition;
[0011] FIG. 4 is a schematic view of the apparatus of FIG. 2 under
a loaded condition;
[0012] FIG. 5 is a schematic view of the apparatus of FIG. 2 under
a different loaded condition; and
[0013] FIG. 6 is a schematic view of the apparatus of FIG. 2 under
a still different loaded condition.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0014] The present invention relates to a seat belt system for a
vehicle. As illustrative of the present invention, a seat belt
system 10 (FIG. 1) includes seat belt webbing 12 for restraining a
vehicle occupant 14, in a driver's seat 16 in a vehicle 18. It is
to be understood that the present invention could also be used with
a seat belt system for restraining an object, such as a child
safety seat or booster seat, in a front or rear passenger seat of
the vehicle 18. The seat belt webbing 12 is extensible about the
vehicle occupant 14. One end of the seat belt webbing 12 is
anchored to the vehicle 18 at an anchor 20 located on one side of
the vehicle seat 16. The opposite end of the seat belt webbing 12
is attached to a seat belt retractor 22 that is typically secured
to the vehicle 18 on the same side of the vehicle seat 16 as the
anchor 20.
[0015] As shown in FIG. 1 intermediate its ends, the seat belt
webbing 12 passes through a tongue assembly 24 and a turning loop,
or D-ring 26, which is located above the retractor 22 and the
anchor point 20. When the seat belt webbing 12 is not in use, the
seat belt webbing is wound on a spool of the retractor 22. The
spool is biased in a direction to wind the webbing on the spool by
a biasing spring, as is known. To use the seat belt webbing 12, the
tongue assembly 24 is extended across the lap and torso of the
vehicle occupant 14 and connected with a buckle 30. The buckle 30
is connected to the vehicle 18 by an anchor 32 on the opposite side
of the vehicle seat 16 from the anchor 20 and the retractor 22.
[0016] An inflatable vehicle occupant protection device, such as an
air bag 43, is stored in an uninflated condition in a portion of
the vehicle 18, such as a steering wheel 40 or a dashboard 41 of
the vehicle. When the vehicle 18 experiences a collision in which
it is desirable to inflate the air bag 43, an inflator 42 is
actuated and provides inflation fluid for inflating the air bag.
The inflation fluid may be generated by combustion of pyrotechnic
material, simply released from a pressurized container, or provided
by a hybrid inflator, all as known in the art. The inflation fluid
directed into the air bag 43 inflates the air bag from the
uninflated condition to an inflated condition (not shown) in which
the air bag extends into an occupant compartment 44 of the vehicle
18. The air bag 43 then helps to protect the vehicle occupant 14
from a forceful impact with a part of the vehicle 18 (i.e., the
steering wheel 40, the dashboard 41, etc.).
[0017] An electronic controller 44, such as a microcomputer, is
operatively connected to a known vehicle collision sensor 45. Once
the controller 44 determines that a collision is occurring and that
inflation of the air bag 43 is necessary to help protect the
vehicle occupant 14 in the vehicle seat 16, the controller actuates
the inflator 42, which is operatively connected to the controller.
The amount of inflation fluid directed into the air bag 43 is
controlled so that the air bag provides a cushioning and
restraining force that is related to the weight of the vehicle
occupant 14 in the vehicle seat 16.
[0018] A weight sensor 50 is mounted on or in the vehicle seat 16.
The weight sensor 50 is operatively connected to the controller 44.
The weight sensor 50 senses a weight of the vehicle occupant 14 or
the object in the vehicle seat 16. The sensed weight may differ
from the actual weight of the vehicle occupant 14 under differing
conditions.
[0019] During normal operation of the vehicle 18, the vehicle
occupant 14 usually has the tongue assembly 24 connected with the
buckle 30. A tension on a lap belt portion of the seat belt webbing
12, including tension applied by the retractor 22, acts on the
vehicle occupant 14. The tension in the lap belt portion of the
seat belt webbing 12 pulls down at an angle on the vehicle occupant
14 (FIG. 1) causing the weight sensor 50 to be subjected to the
weight of the vehicle occupant 14 along with a vertical component
of downward force resulting from the tension in the lap belt
portion of the seat belt webbing 12. The output signal from the
weight sensor 50 thus indicates a sensed weight of the vehicle
occupant 14 which may be greater than the actual weight of the
vehicle occupant.
[0020] Additionally, during a vehicle collision, the vehicle
occupant 14 may tend to move forward in the vehicle and produce a
tension on the seat belt webbing 12. This tension in the seat belt
webbing 12 may pull upward at an angle on the vehicle occupant 14
causing the weight sensor 50 to be subjected to less weight than
the weight sensed during normal operation. The output signal from
the weight sensor 50 thus indicates a sensed weight of the vehicle
occupant 14 which may be less than the actual weight of the vehicle
occupant.
[0021] An apparatus 210 for sensing a seat belt tension load senses
the magnitude of the tension in the seat belt webbing 12 and the
direction that the tension acts on the apparatus 210. The apparatus
210 provides two output signals: the first signal indicating the
vertical component of the tension in the seat belt webbing 12 and
the second signal indicating the direction of the tension. The
output signals from the weight sensor 50 and the apparatus 210 are
received by the controller 44.
[0022] During normal operation, the controller 44 determines a
computed weight of the vehicle occupant 14 as a function of both
the sensed weight and the vertical component of tension in the seat
belt webbing 12. The sensed weight from the weight sensor 50
differs from the actual weight of the vehicle occupant 14 by a
first amount. The computed weight differs from the actual weight of
the vehicle occupant 14 by a second amount that is less than the
first amount and may be zero.
[0023] The controller 44 controls the amount of inflation fluid
directed to the air bag 43 by the inflator 42 based on the computed
weight of the vehicle occupant 14 in the vehicle seat 16. If the
computed weight is below a predetermined value or zero (indicating
the presence of a child seat in the seat or indicating the seat is
not occupied), the controller 44 disables the inflator 42 to
prevent inflation fluid from being directed to the air bag 43.
Alternatively, if the computed weight is below the predetermined
value, the controller 44 may cause the inflator 42 to direct a
minimal amount of inflation fluid to the air bag 43.
[0024] The controller 44 may have in memory a look-up table of a
plurality of empirical sensed weight values, a plurality of
empirical vertical component of seat belt tension values, and a
plurality of computed weight values corresponding to combining of
the sensed weight values and the vertical component of tension
values. The computed weight values stored in the look-up table
could be predetermined empirically and/or through computations
based on a predetermined functional relationship between the values
of the sensed weight and the vertical component of tension.
[0025] The controller 44 can then identify a predetermined computed
weight value corresponding to empirical values of the sensed weight
and the vertical component of tension. Alternatively, the
controller 44 could determine the computed weight by performing a
computation based on a predetermined functional relationship
between the sensed weight and the vertical component of tension
that is derived from empirical data. One such functional
relationship could be subtracting the vertical component of tension
from the sensed weight (during normal vehicle operation). In either
case, the computed weight determined by the controller 44 more
closely approximates the actual weight of the vehicle occupant 14,
as compared with the sensed weight indicated by the weight sensor
50, since the effect of the vertical component of tension in the
seat belt webbing 12 is considered in determining the computed
weight.
[0026] The controller 44 uses the output signal indicative of the
direction of the tension in the seat belt webbing 12 to determine
the size and shape of the object in the vehicle seat 16. The
direction of tension indicates whether a child safety seat or
booster seat is positioned in a front or rear passenger seat in the
vehicle 18. A supplemental sensor of known type may also be used to
sense the size and shape of the object in the seat to determine if
a child safety seat or booster seat is positioned in the passenger
seat.
[0027] If a child safety seat or booster seat is positioned in the
seat, the tongue assembly 24 is connected with the buckle 30 to
secure the child safety seat or booster seat to the seat.
Typically, the seat belt webbing 12 is pulled as tight as possible
to secure the child safety seat or booster seat to the seat. The
tension in the seat belt webbing 12 pulls down on the child safety
seat or booster seat causing the weight sensor 50 to be subjected
to the weight of the child safety seat or booster seat with the
child therein and the downward force resulting from the vertical
component of tension in the seat belt webbing. The output signal
from the weight sensor 50 thus indicates a sensed weight of the
child safety seat or booster seat and the child therein which is
greater than the actual weight of the child safety seat or booster
seat and the child.
[0028] The apparatus 210 provides output signals indicative of the
vertical component of tension in the seat belt webbing 12 and the
direction of the tension. The controller 44 determines the computed
weight of the child safety seat or booster seat and the child
therein. If the weight sensor 50 senses that a child safety seat or
booster seat is positioned in the seat, the controller 44 disables
the source of inflation fluid to prevent inflation of the air bag
43. Alternatively, if the weight sensor 50 senses that a child
safety seat or booster seat is positioned in the passenger seat,
the controller 44 may cause the source of inflation fluid to direct
a minimal amount of inflation fluid to the air bag 43.
[0029] The direction signal also is used to determine the presence
of a child safety seat or booster seat in the seat. If the
direction signal indicates that the seat belt webbing 12 is under
tension at an angle relative to vertical less than a predetermined
amount, the controller 44 will then determine that a child safety
seat or booster seat is present. Typically such an angle is
45.degree..
[0030] The apparatus 210 includes a dual parallelogram linkage 220;
a housing 280 for connection to the seat belt webbing 12; and a
fixture block 510, for attaching the apparatus to the floor pan of
the vehicle 18 at the anchor 20. The apparatus 210 further includes
a restriction plate 520 for preventing over-travel of the dual
parallelogram linkage 220; and a fastener assembly 610 for
interconnecting the dual parallelogram linkage, the fixture block
510, and the restriction plate. The dual parallelogram linkage 220
includes a first parallelogram linkage 320 and a second
parallelogram linkage 420 adjacent the first parallelogram
linkage.
[0031] The first parallelogram linkage 320 defines a parallelogram
in a vertical plane perpendicular to the floor pan of the vehicle
18 and parallel to the forward/rearward movement of the vehicle 18.
The first parallelogram linkage 320 includes a first beam 352 and a
second beam 362 extending parallel to the first beam. The first and
second beams 352, 362 have adjacent, fixedly interconnected first
ends 354, 364 that receive at least part of the load from the seat
belt webbing 12. The first and second beams 352, 362 further have
adjacent, fixedly interconnected second ends 356, 366 opposite the
respective first ends 354, 364. Intermediate portions 355, 365 of
the respective first and second beams 352, 362 interconnect the
first ends 354, 364 and second ends 356, 366 of the first and
second beams 352, 362, respectively. The second ends 356, 366
transmit at least part of the load from the seat belt webbing 12 to
the floor pan of the vehicle 18.
[0032] The first and second beams 352, 362 are identical in
construction and bend in response to a load applied to the beams.
The first parallelogram linkage 320 further includes a first sensor
lever 370 interposed between the intermediate portions 355, 365 and
the second ends 356, 366 of the first and second beams 352,
362.
[0033] The intermediate portions 355, 365 of the first and second
beams 352, 362 have smaller vertical dimensions than the ends 354,
356, 364, 366 of each beam 352, 362 (as viewed in FIGS. 2-6). The
intermediate portions 355, 365 are vertically thinner than the ends
354, 356, 364, 366. The vertically larger ends 354, 356, 364, 366
and the intermediate portions 355, 365 of the beams 352, 362 create
a closed parallelogram configuration (as viewed in FIGS. 2-6).
[0034] The first sensor lever 370 has a longitudinal axis 100 in an
unloaded, or unstressed, condition (as viewed in FIG. 3). The first
and second beams 352, 362 are disposed above and below,
respectively, the axis 100 of the first sensor lever 370 with the
intermediate portions 355, 365 of the beams located at equal
distances from the axis (as viewed in FIG. 3). The first sensor
lever 370 further has a first end portion 372 and a second end
portion 374 opposite the first end portion. The second end portion
374 of the first sensor lever 370 is interposed between, and has a
fixed connection with, the second ends 356, 366 of the first and
second beams 352, 362. The second end portion 374 of the first
sensor lever 370 has an opening (not shown) for fixing the first
sensor lever 370 in an interposed position between the second ends
356, 366 of the first and second beams 352, 362.
[0035] The first end portion 372 of the first sensor lever 370 is
operatively associated with the intermediate portions 355, 365 of
the first and second beams 352, 362. This arrangement causes the
first sensor lever 370 to bend upon vertical movement of the first
ends 354, 364 of the first and second beams 352, 362 (as viewed in
FIGS. 4-6).
[0036] The first sensor lever 370 typically has a vertical
thickness substantially less than that of each intermediate portion
355, 365 such that the stiffness of the first sensor lever is about
one-tenth that of the combined stiffness of each intermediate
portion. For example, if a ten-pound vertical load would deflect
the first sensor lever 370 a predetermined amount, a one hundred
pound vertical load would be required to deflect the two
intermediate portions 355, 365 that same predetermined amount.
[0037] The first sensor lever 370 and the first and second beams
352, 362 are typically constructed of a suitable spring-like
material such as steel or an engineered laminate. Aluminum may also
be used entirely or in combination with steel or other suitable
metal.
[0038] The first parallelogram linkage 320 further includes a first
sensor 379 for sensing the bending of the first sensor lever 370
and for providing an output signal indicative of the amount of
bending of the first sensor lever. The amount of bending of the
first sensor lever 370 is directly related to the amount of bending
of the first and second beams 352, 362. The first sensor 379
provides an output signal dependent upon the amount of bending of
the first sensor lever 370. The first sensor 379 is typically a
strain gauge sensor that is applied to the first end portion 372 of
the first sensor lever 370, preferably by a silk-screening
process.
[0039] The first end portion 372 of the first sensor lever 370 may
be over-molded with a polymer (not shown) for environmentally
sealing the first sensor 379 mounted thereon. The first end portion
372 of the first sensor lever 370 may then have a greater vertical
thickness than the unsealed second end portion 374 of the first
sensor lever 370.
[0040] The first end portion 372 of the first sensor lever 370
further includes an upper curved surface 375 and a lower curved
surface 377. The upper curved surface 375 engages, or abuts, a
lower surface 358 of the intermediate portion 355 of the first beam
352. The lower curved surface 377 engages, or abuts, an upper
surface 368 of the intermediate portion 365 of the second beam 362.
These curved surfaces 375, 377 may be portions of a sphere or some
other suitably curved shape. The curved surfaces 375, 377 may also
be curved end portions of fasteners, such as rivets, mounted on the
first sensor lever 370 or on the upper and lower surfaces 358, 368
of the intermediate portions 355, 365 of the first and second beams
352, 362.
[0041] The first sensor lever 370 essentially bends only in a
vertical plane about a horizontal axis (as viewed in FIGS. 4-6)
when the load is applied to the apparatus 210. The lower and upper
surfaces 358, 368 of the beams 352, 362 define spherical actuation
points that will "roll" with the upper and lower curved surfaces
375, 377, respectively, if a torsional load, which tends to twist
the first parallelogram linkage 320 about the axis 100, for
example, is placed on the first parallelogram linkage. A lateral
load on the first parallelogram linkage 320, transverse to the axis
100, is transferred through both beams 352, 362 from the seat belt
webbing 12 to the floor pan of the vehicle 18. The first sensor
lever 370, and the first sensor 379, thereby incur minimal
torsional or lateral loading due to the spherical actuation points
that allow minimal torsional deflection of the first sensor lever
370 as the first parallelogram linkage 320 is twisted about the
axis 100.
[0042] The second parallelogram linkage 420 defines a parallelogram
in a vertical plane perpendicular to the floor pan of the vehicle
18 and parallel to the forward/rearward movement of the vehicle 18.
The second parallelogram linkage 420 includes a third beam 452 and
a fourth beam 462 extending parallel to the third beam. The third
and fourth beams 452, 462 have adjacent, fixedly interconnected
first ends 454, 464 that receive part of the load from the seat
belt webbing 12. The third and fourth beams 452, 462 further have
adjacent, fixedly interconnected second ends 456, 466 opposite the
respective first ends 454, 464. Intermediate portions 455, 465 of
the respective third and fourth beams 452, 462 interconnect the
first ends 454, 464 and second ends 456, 466 of the third and
fourth beams 452, 462, respectively. The second ends 456, 466
transmit part of the load from the seat belt webbing 12 to the
floor pan of the vehicle 18.
[0043] The third and fourth beams 452, 462 are identical in
construction and bend in response to a load applied to the beams.
The second parallelogram linkage 420 further includes a second
sensor lever 470 interposed between the intermediate portions 455,
465 and the second ends 456, 466 of the third and fourth beams 452,
462.
[0044] The intermediate portions 455, 465 of the third and fourth
beams 452, 462 have smaller vertical dimensions than the ends 454,
456, 464, 466 of each beam 452, 462 (as viewed in FIGS. 3-6). The
intermediate portions 455, 465 are vertically thinner than the ends
454, 456, 464, 466. The vertically larger ends 454, 456, 464, 466
and the intermediate portions 455, 465 of the beams 452, 462 create
a closed parallelogram configuration (as viewed in FIGS. 3-6).
[0045] The second sensor lever 470 has the same longitudinal axis
100 as the first sensor lever 370 in an unloaded, or unstressed,
condition (as viewed in FIG. 3). The third and fourth beams 452,
462 are disposed above and below, respectively, the axis 100 of the
second sensor lever 370 with the intermediate portions 455, 465 of
the beams located at equal distances from the axis (as viewed in
FIG. 3). The second sensor lever 470 further has a first end
portion 472 and a second end portion 474 opposite the first end
portion. The second end portion 474 of the second sensor lever 470
is interposed between, and has a fixed connection with, the second
ends 456, 466 of the third and fourth beams 452, 462. The second
end portion 474 of the second sensor lever 470 has an opening (not
shown) for fixing the second sensor lever 470 in an interposed
position between the second ends 456, 466 of the third and fourth
beams 452, 462.
[0046] The first end portion 472 of the second sensor lever 470 is
operatively associated with the intermediate portions 455, 465 of
the third and fourth beams 452, 462. This arrangement causes the
second sensor lever 470 to bend upon vertical movement of the first
ends 454, 464 of the third and fourth beams 452, 462 (as viewed in
FIGS. 4-6).
[0047] The second sensor lever 470 typically has a vertical
thickness substantially less than that of each intermediate portion
455, 465 such that the stiffness of the second sensor lever is
about one-tenth that of the combined stiffness of each intermediate
portion. For example, if a ten-pound vertical load would deflect
the second sensor lever 470 a predetermined amount, a one hundred
pound vertical load would be required to deflect the two
intermediate portions 455, 465 that same predetermined amount.
[0048] The second sensor lever 470 and the third and fourth beams
452, 462 are typically constructed of a suitable spring-like
material such as steel or an engineered laminate. Aluminum may also
be used entirely or in combination with steel or other suitable
metal.
[0049] The second parallelogram linkage 420 further includes a
second sensor 479 for sensing the bending of the second sensor
lever 470 and for providing an output signal indicative of the
amount of bending of the second sensor lever. The amount of bending
of the second sensor lever 470 is directly related to the amount of
bending of the third and fourth beams 452, 462. The second sensor
479 provides an output signal dependent upon the amount of bending
of the second sensor lever 470. The second sensor 479 is typically
a strain gauge sensor that is applied to the first end portion 472
of the second sensor lever 470, preferably by a silk-screening
process.
[0050] The first end portion 472 of the second sensor lever 470 may
be over-molded with a polymer (not shown) for environmentally
sealing the second sensor 479 mounted thereon. The first end
portion 472 of the second sensor lever 470 may then have a greater
vertical thickness than the unsealed second end portion 474 of the
second sensor lever 470.
[0051] The first end portion 472 of the second sensor lever 470
further includes an upper curved surface 475 and a lower curved
surface 477. The upper curved surface 475 engages, or abuts, a
lower surface 458 of the intermediate portion 455 of the third beam
452. The lower curved surface 477 engages, or abuts, an upper
surface 468 of the intermediate portion 465 of the fourth beam 462.
These curved surfaces 475, 477 may be portions of a sphere or some
other suitably curved shape. The curved surfaces 475, 477 may also
be curved end portions of fasteners, such as rivets, mounted on the
second sensor lever 470 or on the upper and lower surfaces 458, 468
of the intermediate portions 455, 465 of the third and fourth beams
452, 462.
[0052] The second sensor lever 470 essentially bends only in a
vertical plane about a horizontal axis (as viewed in FIGS. 4-6)
when the load is applied to the apparatus 210. The lower and upper
surfaces 458, 468 of the beams 452, 462 define spherical actuation
points that will "roll" with the upper and lower curved surfaces
475, 477, respectively, if a torsional load, which tends to twist
the second parallelogram linkage 420 about the axis 100, for
example, is placed on the second parallelogram linkage. A lateral
load on the second parallelogram linkage 420, transverse to the
axis 100, is transferred through both beams 452, 462 from the seat
belt webbing 12 to the vehicle floor pan 19. The second sensor
lever 470, and the second sensor 479, thereby incur minimal
torsional or lateral loading due to the spherical actuation points
that allow minimal torsional deflection of the second sensor lever
470 as the second parallelogram linkage 420 is twisted about the
axis 100.
[0053] The housing 280 is typically constructed of a suitable metal
such as steel. The housing 280 has a first end portion 281 for
fixed attachment to the first ends 354, 364 of the first and second
beams 352, 362 and a second end portion 282 for fixed attachment to
the first ends 454, 464 of the third and fourth beams 452, 462. The
housing 280 is attached to the dual parallelogram linkage 220 such
that no rotation can occur about any horizontal axis unless the
entire housing rotates (i.e., no relative rotation).
[0054] The first end portion 281 of the housing 280 includes an
upper horizontal portion 283, a lower horizontal portion 285, and a
vertical intermediate portion 284 interconnecting the upper and
lower portions. The second end portion 282 of the housing 280
includes an upper horizontal portion 293, a lower horizontal
portion 295, and a vertical intermediate portion 294
interconnecting the upper and lower portions (as viewed in FIG.
3).
[0055] The housing further includes a vertical connection member
285 interconnecting the first end portion 281 and the second end
portion 282. An upper part 286 of the connection member 285 has an
opening 287 for attaching the seat belt webbing 12 to the housing
280. The upper part 286 directly receives the load from the seat
belt webbing 12.
[0056] The fastener assembly 610 includes a fastener 620 and a
washer, or fastener member 630. The fastener 620 may be a bolt with
a head that clamps the fastener member 630 against an upper surface
523 of the restriction plate 520. As viewed in FIGS. 3-6, the shaft
of the fastener 620 extends downward from the head through the
fastener member 630, an opening in the restriction plate 520, an
opening in the second ends 356, 456 of the first and third beams
352, 452, an opening in the second end portions 374, 474 of the
first and second sensor levers 370, 470, an opening in the second
ends 366, 466 of the second and fourth beams 362, 462, and into a
threaded opening 511 in the fixture block 510. The fixture block
510 is fixed to the floor pan of the vehicle 18 by fastener, weld,
or other suitable method (not shown).
[0057] The fastener 620, housing 280, and restriction plate 520 may
be constructed of a suitable metal such as stainless steel. Other
corrosion-resistant materials of sufficient strength may also be
used.
[0058] The first beam 352 of the first parallelogram linkage 320
and the third beam 452 of the second parallelogram linkage 420 may
be constructed as a single piece with the second ends 356, 456
comprising a middle portion with an opening for receiving the
fastener 610 (as viewed in FIGS. 2-6). Similarly, the second beam
362 of the first parallelogram linkage 320 and the fourth beam 462
of the second parallelogram linkage 420 may be constructed as a
single piece with the second ends 366, 466 comprising a middle
portion with an opening for receiving the fastener 610 (as viewed
in FIGS. 2-6). The first sensor lever 370 of the first
parallelogram linkage 320 and the second sensor lever 470 of the
second parallelogram linkage 420 also may be constructed as a
single piece with the second end portions 374, 474 comprising a
middle portion for receiving the fastener 610 (as viewed in FIGS.
2-6).
[0059] When a directly upward load (as viewed in FIG. 4) is placed
on the seat belt webbing 12 and the housing 280, the load is
transmitted through the first ends 354, 364 of the first and second
beams 352, 362 and the first ends 454, 464 of the third and fourth
beams 452, 462. Since the second ends 356, 366, 456, 466 of the
first, second, third, and fourth beams 352, 362, 452, 462 are fixed
to the floor pan of the vehicle 18 through the fixture block 510,
the first ends 354, 364, 454, 464 of the first, second, third, and
fourth beams 352, 362, 452, 462 will move upward with the housing
280. As the first ends 354, 364, 454, 464 move upward, the
intermediate portions 355, 365, 455, 465 resiliently deflect upward
(as viewed in FIG. 5).
[0060] The first, second, third, and fourth beams 352, 362, 452,
462 act as spring elements transferring the directly upward load
from the seat belt webbing 12 to the floor pan of the vehicle 18.
The thinner vertical dimensions of the intermediate portions 355,
365, 455, 465 of the first, second, third, and fourth beams 352,
362, 452, 462 facilitate upward deflection of the first ends 354,
364, 454, 464 of the beams while the second ends 356, 366, 456, 466
remain vertically fixed relative to the floor pan of the vehicle
18.
[0061] Because of the fixed attachment of the housing 280 to the
first ends 354, 364, 454, 464 of the first, second, third, and
fourth beams 352, 362, 452, 462, the housing is constrained to move
mainly vertically (linearly upward) when directly upward force is
applied to the housing. The housing 280 is constrained
horizontally. The vertically deflected intermediate portions 355,
365, 455, 465 of the beams 352, 362, 452, 462 thereby assume "S"
shapes (as viewed in FIG. 4).
[0062] When the controller 44 receives the signals from the first
sensor 379 and the second sensor 479, the controller compares the
signals and determines the direction (or angle) of the load by
analyzing the difference (if any) between the magnitude of the
signals. The controller 44 also determines the magnitude of the
vertical component of the load by analyzing the signals. Adding the
output from the two signals is one possible method for determining
this magnitude.
[0063] When an upward and to the right load (as viewed in FIG. 5)
is placed on the seat belt webbing 12 and the housing 280, the load
is transmitted through the first ends 354, 364 of the first and
second beams 352, 362 and the first ends 454, 464 of the third and
fourth beams 452, 462. Since the second ends 356, 366, 456, 466 of
the first, second, third, and fourth beams 352, 362, 452, 462 are
fixed to the floor pan of the vehicle 18 through the fixture block
510, the first ends 354, 364, 454, 464 of the first, second, third,
and fourth beams 352, 362, 452, 462 will move upward with the
housing 280. As the first ends 354, 364, 454, 464 move upward, the
intermediate portions 355, 365, 455, 465 resiliently deflect upward
(as viewed in FIG. 5).
[0064] The first, second, third, and fourth beams 352, 362, 452,
462 act as spring elements transferring the upward, angled load
from the seat belt webbing 12 to the floor pan of the vehicle 18.
The thinner vertical dimensions of the intermediate portions 355,
365, 455, 465 of the first, second, third, and fourth beams 352,
362, 452, 462 facilitate upward deflection of the first ends 354,
364, 454, 464 of the beams while the second ends 356, 366, 456, 466
remain vertically fixed relative to the floor pan of the vehicle
18.
[0065] Because of the fixed attachment of the housing 280 to the
first ends 354, 364, 454, 464 of the first, second, third, and
fourth beams 352, 362, 452, 462, the housing is constrained to move
mainly vertically (linearly upward) with a slight rotation when
upward angled force is applied to the housing. The housing 280 is
constrained horizontally. The vertically deflected intermediate
portions 355, 365, 455, 465 of the beams 352, 362, 452, 462 thereby
assume "S" shapes (as viewed in FIG. 5) with the first sensor lever
370 deflecting upward more than the second sensor lever 470.
[0066] When the controller 44 receives the signals from the first
sensor 379 and the second sensor 479, the controller compares the
signals and determines the direction (or angle) to the right of the
load from a directly vertical load (FIG. 4) by analyzing the
difference between the magnitude of the signals. The controller 44
also determines the magnitude of the vertical component of the load
by analyzing the signals. Adding the output from the two signals is
one possible method for determining this magnitude.
[0067] When an upward and to the left load (as viewed in FIG. 6) is
placed on the seat belt webbing 12 and the housing 280, the load is
transmitted through the first ends 354, 364 of the first and second
beams 352, 362 and the first ends 454, 464 of the third and fourth
beams 452, 462. Since the second ends 356, 366, 456, 466 of the
first, second, third, and fourth beams 352, 362, 452, 462 are fixed
to the floor pan of the vehicle 18 through the fixture block 510,
the first ends 354, 364, 454, 464 of the first, second, third, and
fourth beams 352, 362, 452, 462 will move upward with the housing
280. As the first ends 354, 364, 454, 464 move upward, the
intermediate portions 355, 365, 455, 465 resiliently deflect upward
(as viewed in FIG. 6).
[0068] The first, second, third, and fourth beams 352, 362, 452,
462 act as spring elements transferring the upward, angled load
from the seat belt webbing 12 to the floor pan of the vehicle 18.
The thinner vertical dimensions of the intermediate portions 355,
365, 455, 465 of the first, second, third, and fourth beams 352,
362, 452, 462 facilitate upward deflection of the first ends 354,
364, 454, 464 of the beams while the second ends 356, 366, 456, 466
remain vertically fixed relative to the floor pan of the vehicle
18.
[0069] Because of the fixed attachment of the housing 280 to the
first ends 354, 364, 454, 464 of the first, second, third, and
fourth beams 352, 362, 452, 462, the housing is constrained to move
mainly vertically (linearly upward) with a slight rotation when
upward angled force is applied to the housing. The housing 280 is
constrained horizontally. The vertically deflected intermediate
portions 355, 365, 455, 465 of the beams 352, 362, 452, 462 thereby
assume "S" shapes (as viewed in FIG. 6) with the first sensor lever
deflecting upward less than the second sensor lever 470.
[0070] When the controller 44 receives the signals from the first
sensor 379 and the second sensor 479, the controller compares the
signals and determines the direction (or angle) to the left of the
load from a directly vertical load (FIG. 4) by analyzing the
difference between the magnitude of the signals. The controller 44
also determines the magnitude of the vertical component of the load
by analyzing the signals. Adding the output from the two signals is
one possible method for determining this magnitude.
[0071] The dual parallelogram linkage 220 may receive cross-car
forces that act transverse to the axis 100 of the first and second
sensor levers 370, 470. Such forces may impart torsional forces
about the axis 100 to the first, second, third, and fourth beams
352, 362, 452, 462, as discussed above. However, any rotation that
is incurred by the dual parallelogram linkage 220 about the axis
100 will not significantly affect the spring rate, or stiffness, of
the beams 352, 362, 452, 462 to vertical loading at the first ends
354, 364, 454, 464. The dual, identical beam configuration of the
first and second parallelogram linkages 320, 420, with each beam
352, 362, 452, 462 identically associated with the axis 100,
balances any rotation about the axis created by this torsional
loading such that the effective moment of inertia of the beams
about the axis remains unchanged even when the beams are under a
deflected condition. For example, if torsional loading of the beams
352, 362, 452, 462 has occurred, tension or compression stresses
induced in the first and third beams 352, 452 would be offset by
equal and opposite tension and compression stresses induced in the
second and fourth beams 362, 462.
[0072] Further, the first and third beams 352, 462, acting in
tandem with the second and fourth beams 362, 462, balance any
cross-sectional deformations of the beams that would alter the
vertical spring rate (i.e., if only beams on one side of the axis
100 would be utilized, etc.). The torsional reaction of the dual
beam configuration is thus equal about the axis 100, but opposite,
and the vertical spring rate remains constant even after some
deflection (and some cross-sectional deformation) has occurred.
[0073] The relationship, or spring rate, of the vertical load
placed on the first ends 354, 364, 454, 464 of the beams 352, 362,
452, 462 by the seat belt webbing 12 and the housing 280 to the
vertical displacement of the first ends of the beams is linear,
constantly proportional, predictable, and consistent for differing
amounts of upward travel of the first ends. Thus the output of the
first and second sensors 379, 479 on the first and second sensor
levers 370, 470 is also linear, constantly proportional,
predictable, and consistent for both parallelogram linkages 320,
420.
[0074] The restriction plate 520 provides travel stops for the dual
parallelogram linkage 220. The restriction plate 520 has a first
end portion 521 and a second end portion 522 opposite the first end
portion. A lower surface 531 of the first end portion 521 prevents
the first end portion 281 of the housing 280 from moving upward
more than a predetermined amount as an upper surface 283a of the
first end portion 281 of the housing 280 engages the lower surface
531. A lower surface 532 of the second end portion 522 prevents the
second end portion 282 of the housing 280 from moving upward more
than a predetermined amount as an upper surface 293a of the second
end portion 282 of the housing 280 engages the upper surface 532.
The typical upward amount of travel permitted by these stops is 1.0
mm.
[0075] Any initial stresses incurred by the first and second
sensors 379, 479 due to initial bending of the first and/or second
sensor levers 370, 470 caused by manufacturing tolerances or
assembly tolerances (i.e., tightening of the fastener, etc.) may be
factored out during an initial calibration of the first and second
sensors. The first and second sensor levers 370, 470 essentially
bend only in a vertical plane about a horizontal axis (FIGS. 4-6).
As stated earlier, torsional and lateral stresses are decoupled
from the bending stresses by the upper and lower curved surfaces
375, 377, 475, 477 of the first end portions 372, 472 of the first
and second sensor levers 370, 470. Because the seat belt webbing 12
generally imparts upward loads to the dual parallelogram linkage
220, the upper curved surfaces 375, 475 mainly provide stability to
the first and second sensor levers 370, 470 and ensure that the
first and second sensor levers 370, 470 return to their neutral
positions (FIG. 3). The intermediate portions 355, 365, 455, 465 of
the first, second, third, and fourth beams 352, 362, 452, 362, much
thicker than the first and second sensor levers 370, 470, support
loads created by the seat belt webbing 12 and transmit these loads
to the vehicle floor pan 19.
[0076] The first end portions 372, 472 of the first and second
sensor levers 370, 470 may thereby pivot, or rotate, slightly as
the first end portions 372, 472 are forced upward by the
intermediate portions 365, 465 of the second and fourth beams 362,
462. As viewed in FIGS. 4-6, the first, second, third, and fourth
beams 352, 362, 452, 462 are forced into the "S" shapes while the
first and second sensor levers 370, 470 are bent upward as simple
cantilevers.
[0077] The first and second sensors 379, 479 produce output signals
directly proportional to the vertical force applied to the seat
belt webbing 12. Overloading of the first and second sensors 379,
479 is prevented by the lower surfaces 531, 532 of the first and
second end portions 521, 522 of the restriction plate 520, as
discussed above. The first and second sensors 379, 479, while
preferably strain gauge sensors, may be any suitable sensors.
[0078] From the above description of the invention, those skilled
in the art will perceive improvements, changes and modifications.
Such improvements, changes and modifications are intended to be
included within the scope of the appended claims.
* * * * *