U.S. patent application number 09/748489 was filed with the patent office on 2001-05-10 for crush sensing vehicle crash sensor.
Invention is credited to Breed, David S., Downs, Richard M. JR., Sanders, William Thomas.
Application Number | 20010000886 09/748489 |
Document ID | / |
Family ID | 27487275 |
Filed Date | 2001-05-10 |
United States Patent
Application |
20010000886 |
Kind Code |
A1 |
Breed, David S. ; et
al. |
May 10, 2001 |
Crush sensing vehicle crash sensor
Abstract
A vehicle crush detecting device including an electrically
conducting tube with an electrically conducting rod positioned
within the tube along with insulating means positioned at at least
two points between the rod and tube to insulate the rod from the
tube. The electrically conducting tube is deformed during a vehicle
crash causing the tube to contact the rod in response to crush of
the vehicle. A header/connector assembly seals a space between the
rod and tube at one end while a space between the rod and tube at
the opposite end is closed. The header/connector assembly includes
electrical connector pins electrically coupled to the rod and tube
and having an exposed portion for connection to a wire harness. The
device is used to sense crashes for the deployment of automobile
passive restraint systems such as airbags.
Inventors: |
Breed, David S.; (Boonton
Township, NJ) ; Sanders, William Thomas; (Rockaway
Twp., NJ) ; Downs, Richard M. JR.; (Arlington,
VA) |
Correspondence
Address: |
BRIAN ROFFE, ESQ
366 LONGACRE AVENUE
WOODMERE
NY
11598
|
Family ID: |
27487275 |
Appl. No.: |
09/748489 |
Filed: |
December 26, 2000 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09748489 |
Dec 26, 2000 |
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08514986 |
Aug 14, 1995 |
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6206129 |
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08514986 |
Aug 14, 1995 |
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08024076 |
Mar 1, 1993 |
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5441301 |
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08024076 |
Mar 1, 1993 |
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07795035 |
Nov 20, 1991 |
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5326133 |
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08024076 |
Mar 1, 1993 |
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07727756 |
Jul 9, 1991 |
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Current U.S.
Class: |
180/274 |
Current CPC
Class: |
B60R 19/483 20130101;
B60N 2/002 20130101; B60N 2/2863 20130101; H01H 35/146 20130101;
B60J 10/00 20130101; B62D 21/15 20130101; G01F 23/2962 20130101;
G01F 23/2965 20130101; B60R 21/0136 20130101; G01F 23/804 20220101;
G01F 23/20 20130101 |
Class at
Publication: |
180/274 |
International
Class: |
B60R 021/00 |
Claims
What is claimed is:
1. A vehicle crush detecting device in combination with a vehicle,
comprising: a sensor assembly consisting of a first elongated
electrical conductor, a second elongated electrical conductor, and
means for coupling said second electrical conductor to said first
electrical conductor so that said first and second electrical
conductors are parallel and substantially co-extensive to each
other and thereby form the sensor assembly, said coupling means
maintaining a separation between said second electrical conductor
from said first electrical conductor; and attachment means for
attaching said sensor assembly to said vehicle; wherein when a
portion of said vehicle crushes to contact said sensor assembly,
said sensor assembly bends causing said first electrical conductor
to contact said second electrical conductor and complete an
electric circuit indicative of crush of said vehicle.
2. The combination of claim 1, wherein said attachment means
attached said sensor assembly to said vehicle at at least two
spaced apart positions providing thereby at least one free,
unrestrained span between said at least two spaced apart locations
which is spaced away and not in contact with any part of said
vehicle; wherein when a portion of said vehicle crushes to contact
said sensor assembly in said span between said at least two spaced
apart locations, said sensor assembly bends in said span between
said at least two spaced apart locations causing said first
electrical conductor to contact said second electrical conductor
and complete an electric circuit indicative of crush of said
vehicle.
3. The combination in accordance with claim 1, wherein said
coupling means include a header/connector assembly arranged at one
end of said sensor assembly.
4. The combination in accordance with claim 3, wherein said
header/connector assembly hermetically seals a space between said
first and second conductors at first ends of said first and second
conductors, a space between said first and second conductors at
second ends being closed, said header/connector assembly including
electrical connector pins electrically coupled to said first and
second conductors, said connector pins having an exposed
portion.
5. The combination in accordance with claim 4, wherein said
header/connector assembly further includes a housing having an
inlet port, a dam in the space between said first and second
conductors at said first ends of said first and second conductors
and urethane or a silicone rubber compound around said first ends
of said first and second conductors.
6. The combination in accordance with claim 4, wherein said
header/connector assembly further includes header pins connected to
said first and second conductors, said connector pins being
connected to said header pins.
7. The combination in accordance with claim 1, wherein said first
conductor is a tube surrounding said second conductor and is welded
closed at one end to thereby seal a space between said first and
second conductors at said end.
8. The combination in accordance with claim 7, wherein said
coupling means include a resistor arranged between the closed end
of said first conductor and a proximate end of said second
conductor.
9. The combination in accordance with claim 1, wherein said first
conductor is a tube and said second conductor is a rod arranged in
said tube.
10. The combination in accordance with claim 9, wherein said tube
is deformable such that contact of said rod by said tube is caused
by bending of said tube.
11. The combination in accordance with claim 9, wherein said rod
and said tube are unitary and said rod is substantially solid.
12. The combination in accordance with claim 1, farther comprising
insulating means positioned at at least two points between said
first and second conductors for insulating said first conductor
from said second conductor.
13. The combination in accordance with claim 12, wherein said
insulating means comprise spacers extending only at discrete
locations circumferentially between said first and second
conductors only at discrete locations..
14. The combination in accordance with claim 1, wherein said first
conductor surrounds said second conductor and contains grease.
15. The combination in accordance with claim 1, wherein said
attachment means attach said sensor assembly to said vehicle in a
front region of the vehicle so as to detect crush of the front
region of said vehicle.
16. The combination in accordance with claim 1, wherein said
attachment means attach said sensor assembly to said vehicle at a
rear of the vehicle so as to detect crush of the rear of said
vehicle.
17. The combination in accordance with claim 1, wherein said
vehicle has a side and a deployable occupant protection apparatus
for protecting an occupant in a side impact, said attachment means
attaching said sensor assembly to said vehicle on a side of the
vehicle so as to detect crush of the side of said vehicle, the
combination further comprising means for coupling said crush
detecting device and said occupant protection apparatus such that
upon completion of said electronic circuit, said occupant
protection device is deployed.
18. The combination in accordance with claim 17, wherein said
sensor assembly has an elongate portion attached by said attachment
means in a position substantially parallel to a door panel in a
door on said side of said vehicle.
19. The combination in accordance with claim 1, further comprising:
a deployable occupant protection device, an electronic sensor
coupled to said sensor assembly and comprising an accelerometer,
and means coupled to said accelerometer for initiating deployment
of said occupant protection device based on completion of the
electric circuit indicative of crush of said vehicle and an
analysis of output from said accelerometer indicative of a
situation in which deployment of said occupant protection device is
desired.
20. A vehicle crush detecting device, comprising a first electrical
conductor having first and second ends, a second electrical
conductor having first and second ends and arranged relative to
said first conductor to define a space between said first and
second conductors, and a header/connector assembly for hermetically
sealing the space between said first and second conductors at said
first ends of said first and second conductors, the space between
said first and second conductors at said second ends being closed,
said header/connector assembly including electrical connector pins
electrically coupled to said first and second conductors, said
connector pins having an exposed portion; said first conductor
being arranged to bend upon exertion of a force to said first
conductor and thereby contact said second conductor with such
contact being indicative of crush of the vehicle.
21. The device in accordance with claim 20, wherein said
header/connector assembly comprises a housing having an inlet port,
a dam in the space between said first and second conductors at said
first ends of said first and second conductors and urethane or a
silicone rubber compound around said first ends of said first and
second conductors.
22. The device in accordance with claim 20, further comprising
header pins connected to said first and second conductors, said
connector pins being connected to said header pins.
23. The device in accordance with claim 20, wherein said first
conductor is welded closed at said second end to thereby seal the
space between said first and second conductors at said second
ends.
24. The device in accordance with claim 23, wherein said
header/connector assembly further comprises a resistor arranged
between said second end of said second conductor and said second
end of said first conductor.
25. A method for sealing a device for mounting on an automobile,
comprising the steps of: providing the device with a cavity having
at least one inlet port and at least one narrow outflow passage,
injecting a curable compound through the at least one inlet port
such that the at least one narrow passage remains open during the
injection process until the cavity is substantially full permitting
air within the cavity to be displaced by the curable compound, the
at least one passage being sufficiently narrow as to permit only a
small amount of rubber compound to flow out of the cavity during
the injection process, but large enough to permit air to easily
flow out of the assembly; and curing the compound.
26. The method of claim 25, wherein the device is a crush detecting
switch comprising an electrically conductive tube and an
electrically conductive rod arranged within the tube and spaced
therefrom, further comprising the step of forming the cavity at
least partially between the tube and the rod.
27. The method of claim 25, wherein the device is a crash detecting
switch comprising an electrically conductive tube and an
electrically conductive rod arranged within the tube and spaced
therefrom, further comprising the steps of: forming a plurality of
the cavities between discrete regions of the tube and the rod,
separating each of the cavities by means of spacers, and connecting
the cavities through an aperture in the spacers to enable the
injected curable compound to flow into each of the cavities.
28. The method of claim 25, wherein the curable compound is a
rubber compound.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
1. This application is a continuation of U.S. patent application
Ser. No. 08/514,986 filed Aug. 14, 1995, which in turn is a
continuation-in-part of U.S. patent application Ser. No. 08/024,076
filed Mar. 1, 1993, now U.S. Pat. No. 5,441,301, which in turn is a
continuation-in-part of (i) U.S. patent application Ser. No.
07/795,035 filed Nov. 20, 1991, now U.S. Pat. No. 5,326,133, (ii)
U.S. patent application Ser. No. 07/727,756, filed Jul. 9, 1991,
now abandoned, all of which are incorporated herein by reference.
This invention is also an improvement on the invention disclosed in
U.S. Pat. No. 4,995,639 and a full discussion of the background of
this general type of sensor is disclosed in that patent and is
incorporated herein by reference.
BACKGROUND OF THE INVENTION
2. In Society of Automotive Engineers (SAE) paper No. 930650
entitled "A Complete Frontal Crash Sensor System - I", by Breed et
al, which is incorporated herein by reference, the authors conclude
that airbag crash sensors mounted in the crush zone are necessary
for the proper sensing of airbag-required frontal crashes. They
also conclude that such sensors should sense crashes to all
portions of the front of the vehicle and that sensors which sense
the crush of the vehicle are preferred. The theory of crush sensing
is presented in the above-referenced U.S. patents and patent
applications and in SAE paper No. 920122 entitled, "Performance of
a Crush Sensor for Use with Automotive Airbag Systems", by Breed et
al, which is incorporated herein by reference.
3. The tape switch and rod-in-tube crush sensors described in the
above-referenced U.S. patents and patent applications, have
performed successfully on various staged vehicle frontal crashes
into barriers and poles. These sensors are generally not sufficient
for sensing side impacts as discussed in Breed, D. S., Sanders, W.
T. and Castelli, V., "Sensing Side Impacts", Society of Automotive
Engineers (SAE) paper No. 940561, 1994, however, they can be
successful when used in conjunction with a passenger compartment
mounted electronic sensor or as a safing sensor. Similarly, they
are also being considered when a deployable device, such as an
airbag, is used for rear impacts.
4. Other technical papers which provide pertinent background
information to this invention include:
5. 1. Breed, D. S., Castelli, V. "Problems in Design and
Engineering of Air Bag Systems", Society of Automotive Engineers
paper No. 880724, 1988.
6. 2. Breed, D. S., Castelli, V. "Trends in Sensing Frontal
Impacts", Society of Automotive Engineers paper No. 890750,
1989.
7. 3. Castelli, V., Breed, D. S. "Trends in Sensing Side Impacts",
Society of Automotive Engineers paper No. 890603, 1989.
8. 4. Breed, D. S., Castelli, V. and Shokoohi, F. "Are Barrier
Crashes Sufficient for Evaluating Air Bag Sensor Performance?",
Society of Automotive Engineers paper No. 900548, 1990.
9. 5. Breed, D. S., Sanders, W. T. and Castelli, V. "A Critique of
Single Point Crash Sensing", Society of Automotive Engineers paper
No. 920124, 1992.
10. 6. Breed, D. S., Sanders, W. T. and Castelli, V. "Performance
of a Crush Sensor for Use with Automobile airbag Systems", Society
of Automotive Engineers paper No. 920122, 1992.
11. 7. Shokoohi, F., Sanders, W. T., Castelli, V., and Breed, D. S.
"Cross Axis Specifications For Crash Sensors", Automotive
Technologies International Report, ATI 12004, 1991. Society of
Automotive Engineers paper No. 930651, 1993.
12. 8. Breed, D. S., Sanders, W. T. and Castelli, V. "A complete
Frontal Crash Sensor System I", Society of Automotive Engineers
paper No. 930650, 1993.
13. 9. Breed, D. S. and Sanders, W. T. "Using Vehicle Deformation
to Sense Crashes", Presented at the International Body and
Engineering Conference, Detroit MI, 1993.
14. 10. Breed, D. S., Sanders, W. T. and Castelli, V., "A complete
Frontal Crash Sensor System II", Proceedings Enhanced Safety of
Vehicles Conference, Munich, 1994, Published by the U.S. Department
of Transportation, National Highway Traffic Safety Administration,
Washington, D.C.
15. 11. Breed, D. S., Sanders, W. T. and Castelli, V., "Sensing
Side Impacts", Society of Automotive Engineers paper No. 940561,
1994.
16. 12. Breed, D. S., "Side Impact Airbag System Technology",
Presented at the International Body and Engineering Conference,
Detroit MI, 1994.
17. Other relevant prior art includes U.S. Pat. No. 3,859,482 to
Matsui which will now be discussed in some detail. Matsui shows
various devices which respond to the force (pressure using Matsui's
terminology) which accompanies a vehicle frontal crash when
material in the extreme front of the vehicle, or the impacting
object itself, impacts the force detecting device. Matsui also
mentions, but does not illustrate, the use of his force detectors
on the rear and the side of the vehicle. The Matsui devices
discriminate crashes based on the magnitude of this force on the
detecting device, which as stated in the patent, are in the order
of tons (metric). Many devices are described in Matsui however the
following generalizations apply:
18. 1. The Matsui sensors are mechanical pressure (force) detecting
devices. This is stated in the title of the patent and throughout,
there is only discussion of pressure being applied directly to the
sensor. Except in those cases where a tape switch or a rope is used
as the forwardmost point on the vehicle, there is always associated
with the device a "Presser Member" whose function is to apply force
directly to the sensor. Most importantly, this is a device which
determines the severity of a crash based on force where the force
is in the order of metric tons.
19. As discussed in greater detail below, the devices disclosed in
the instant invention are displacement sensors not force sensors,
they do not require tons of force to actuated, are never placed at
the forward most point on the vehicle, a "Presser Member" is not
required or used, and they are designed to function by bending and
not by compression.
20. 2. The Matsui sensors are used in combination with a high level
deceleration detector. In all cases, the Matsui sensor is used in
conjunction with an acceleration sensor. This sensor is a low level
discriminating sensor which is different from the safing sensor
used on most current airbag systems. The difference between these
types of sensors is that the Matsui sensor is not used alone to
discriminate the crash, that is to determine whether the crash
requires deployment of an airbag. An additional discriminating
sensor is required. By contrast, in conventional airbag systems, a
safing or arming sensor is used to guard against electrical shorts
in the sensor perhaps caused by vehicle maintenance. The safing
sensor will trigger on pothole impacts for example. It is not
intended to provide information as to the severity of the crash.
This is not the case in the Matsui acceleration sensor which is
used in series with a force sensor. This is clear by the
illustrated embodiment in FIG. 29 which shows that the deceleration
sensor requires a value of acceleration to trigger which is shown
to be a substantial percent of the peak deceleration of curve A
which is on the order of about 40 G's (see for example FIG. 1 of
reference 1 above). In contrast, typical safing or arming sensors
trigger on a deceleration of less than about 2 G's.
21. Again, as will be discussed in detail below, in contrast, the
sensors of the present invention do not require a high level
deceleration sensor or any deceleration sensor for that matter.
When the sensors of this invention are used as discriminating
sensors, a low level safing or arming sensor can optionally be used
to provide electrical isolation of the inflator initiator so that
momentary electrical shorts do not cause deployment of the airbag.
In other cases, they are used as safing sensors, for example in
side impact sensing arrangements. There is no hint in Matsui of
using his sensors as safing sensors.
22. 3. In many illustrations of the Matsui devices a frangible
system is used. In one case, for example, a wire inside a glass
tube, or a glass rod or tube which has been plated with silver, is
used. In some of these cases, a sensor design is illustrated which
is substantially longer that it is thick or wide. In this manner,
the sensor can extend across a significant portion of the vehicle
in much the same way that the rod-in-tube sensors of the instant
invention are implemented. These frangible sensors trigger by being
broken, usually by means of a "Presser Member" and to thereby break
an electric circuit.
23. As discussed below, in contrast, the sensors of this invention
are not frangible and trigger by bending not by breaking.
24. 4. Due to the requirement that tons of force are needed to
trigger the Matsui sensor, rigid mounting thereof is a requirement.
This is particularly important at the place on the sensor where
triggering is intended to occur.
25. As set forth below, in contrast, the sensors of this invention
trigger on bending and therefore should not in general be rigidly
mounted particularly at the point where contract between the rod
and tube is intended.
26. 5. Tape switch implantation uses pressure actuated tape
switches not those designed to by actuated by bending. Matsui
explicitly states that the tape switch implementations disclosed
are actuated by pressure (column 26, lines 20-23).
27. As discussed below, the sensors of the instant invention
trigger on bending generally before sufficient force is available
to crush the sensor.
28. 6. The elongated sensors illustrated by Matsui are flexible
lines systems, i.e., either frangible, pressure sensing tape
switches, or sensors made by stretching a line or rope. All of
these designs differ significantly from the rod-in-tube sensors of
the instant invention. The remaining sensors disclosed are all
point sensors which trigger when tons of force are applied to the
sensor surface. In none of these cases is a sensor designed to be
triggered by bending suggested.
29. 7. In spite of the large potpourri of sensor designs disclosed,
all of which have serious technical deficiencies, nowhere does
Matsui suggest a rod-in-tube geometry of the sensor. The
rod-in-tube geometry permits the sensor to be arbitrarily formed so
that it covers all portions of the vehicle which are likely to be
involved in a crash. In contrast, the elongated sensors of Matsui
are typically shown mounted onto the bumper (erroneously designated
as the fender) or immediately behind the bumper. An observation of
frontal impacts shows that in approximately 30% of frontal airbag
required accidents the bumper is not impacted. Thus, for these
cases the Matsui sensor would not trigger.
30. For the purposes herein, the crush zone is defined as that part
of the vehicle which crushes or deforms during a particular crash.
This is a different definition from that used elsewhere and in
particular in the above referenced technical papers. Also for the
purposes herein, the terminology Crush Sensing Zone, or CSZ, will
be used to designate that portion of the vehicle which is deformed
or crushed during a crash at the sensor required trigger time. The
sensor required trigger time is considered the latest time that a
crash sensor can trigger for there to be sufficient time to deploy
the airbag. This is determined by the airbag system designers and
is a given parameter to the sensor designer for a particular crash.
Naturally, there will be a different required sensor triggering
time for each crash, however, it has been found, as reported in the
above references, that the CSZ is remarkably constant for all
crashes of the same type.
31. For example, the CSZ is nearly the same for all frontal barrier
crashes regardless of the velocity of the crash. The same is true
for 30 degree angle barrier crashes although the CSZ is different
here than for frontal barrier crashes. Remarkably, and
unexpectedly, it has also been found that when all frontal crashes
at all different velocities are taken into account, the CSZ
rearmost boundary becomes an approximate three dimensional surface
lying mostly within the engine compartment of the vehicle,
typically about ten to twelve inches behind the bumper at the
center, and extending backward when crashes outside of the rails
are considered. Finally, if a sensor is placed on this CSZ surface
so that it is higher than the bumper level on the sides of the
vehicle and lower in the vehicle center, as shown in FIG. 1 herein,
it will do a remarkable job at discriminating between airbag
required and non-deployment crashes and still trigger by the sensor
required triggering time and before other sensors of comparable
sensitivity. Naturally, this system is not perfect, however, it has
been shown to do a better job than any other sensor system now in
use.
32. It was this discovery which provided a basis for the subject
matter described in U.S. Pat. No. 4,995,639 and then to the
rod-in-tube sensor described in U.S Pat. No. 5,441,301. During the
process of implementing the rod-in-tube sensor, it was found that
the same theory applies to rear impacts and that rod-in-tube
sensors also have applicability to side impact sensing, although
the theory is different.
33. In U.S. Pat. No. 5,694,320 (Breed), incorporated by reference
herein,, the theory of sensing rear impacts is presented and it is
concluded that an anticipatory sensing system is preferred. This is
because many people suffer whiplash injuries at rather low velocity
impacts and if an inflatable restraint is used, the repair cost may
be significant. To protect most people from whiplash injuries in
rear impacts, therefore, a resetable system is preferred. The
argument on the other side is that if the headrest is properly
positioned, it will take care of all of the low velocity impacts
and, therefore, an airbag can be used and reserved for the high
velocity impacts where a crush sensing crash sensor would be used.
The rod-in-tube sensor disclosed herein is, therefore, ideal for
use with a deployable headrest mounted airbag for the same reasons
that it is the best sensor for sensing frontal impacts. Since the
rear of a vehicle typically has about one third of the stiffness of
the vehicle front, electronic sensors will have even a tougher time
discriminating between trigger and non-trigger cases for rear
impacts. As disclosed in references 5 and 9 above, it is the soft
crashes which are the most difficult for electronic sensors to
sense in time.
34. Crush sensing crash sensors are not ideal for sensing side
impacts alone, although the Volvo side impact system uses such a
sensing system. This is because the sensing time is so short that
there is virtually no crush (about two inches) at the time that the
airbag must be deployed. Since there is very little signal out of
the crush zone where electronic sensors are mounted, electronic
sensors alone are not able to discriminate airbag required crashes
from other crashes not requiring airbag deployment. The combination
of the two sensors, on the other hand, can be used to provide a
reliable determination. The crush sensor determines that there has
been two inches of crush and the electronic sensor determines that
the acceleration signal at that time is consistent with there being
an airbag required crash. Thus, although they cannot be reliably
used alone as a discriminating sensor for side impacts, the
combined system does function properly.
35. An alternate use of the crush sensor such as the rod-in-tube
sensor in side impacts is as a safing sensor. In this role, it
merely determines that a crash is in progress and the main
discriminating function is handled by the velocity sensing sensors
such as disclosed in U.S. Pat. No. 5,231,253 (assigned to the
current assignee).
36. Applications for the rod-in-tube crush sensing crash sensor
thus include frontal, side and rear impacts, where in each case
they enjoy significant advantages over all other crash sensing
technologies. Examples of the preferred implementations are
described in the paragraphs below.
37. With respect to other prior art related to the invention,
Peachey (U.S. Pat. No. 4,060,705) describes a pressure actuated
continuous switch which designed to actuate about its entire
circumference, i.e., in all directions. The switch of the
embodiment in FIG. 1 of Peachey includes a central, inner conductor
1, an insulating thread 2 helically wound around the conductor 1
and an outer conductor 3, all housed within a sheath of insulating
material 4. The switch in the embodiment of FIG. 2 includes a
central, inner conductor 1, an insulating thread 2 helically wound
around the conductor 1, a sheath of graphite-loaded plastic 5
surrounding the thread 2, an outer conductor 3 surrounding the
sheath 5 and a sheath of insulating material 4 surrounding the
outer conductor 3. The switch in these embodiments is actuated when
pressure is applied to the switch so that the outer conductor (FIG.
1) or sheath 5 (FIG. 2) is deflected to cause it to make contact
with the inner conductor 1 and thereby establish electrical contact
between the inner and outer conductors 1,3, in the embodiment of
FIG. 2 through the sheath 5. In view of the helical winding of the
insulating thread 2 around the inner conductor 1, these switches
can be actuated by bending at almost all locations (except for an
impact into a location where the insulating material 2 is
interposed between the conductors 1,3.
38. U.S. Pat. No. 2,437,969 to Paul describes a deformable switch
10 in the form of a tube that is actuatable at all circumferential
points along its length. The tube includes a central coil of
electrically conducting wire 12, a braided electrically conducting,
metal tube 11 and insulating separators 13 spaced at discrete
locations along the length of the switch 10 to support the tube 11
around the wire 12. The switch is actuatable at all circumferential
locations along the length of the tube, except for the locations at
which the insulating separators 13 are located. In use, when
pressure is applied to the tube 11, it deforms at the location at
which pressure is applied thereby coming into contact with the wire
11 and causing a circuit to close.
39. U.S. Pat. No. 5,322,323 to Ohno et al. describes to a collision
sensing system for an airbag including collision sensors and
acceleration sensors wherein deployment of the airbag is based on a
signal from the collision sensors and an analysis of the output
from the acceleration sensors.
OBJECTS AND SUMMARY OF THE INVENTION
40. Principle objects and advantages of this invention are:
41. 1) To provide a single sensor which will sense all airbag
desired crashes involving the either the front, rear or a side of
the vehicle.
42. 2) To provide a sensor which is much longer than it is wide or
thick thus permitting it to sense crashes over a large area while
occupying a relatively small space.
43. 3) To provide a sensor which can be easily shaped so to be
properly placed at the CSZ boundary across the entire front or rear
of the vehicle.
44. 4) To provide a crush sensor where the deformation required to
trigger the sensor can be varied along the length of the
sensor.
45. 5) To provide a sensor to be used in conjunction with an
electronic passenger compartment mounted sensor which will trigger
on all of the airbag desired crashes which are missed by the
electronic passenger compartment mounted sensor alone for either
frontal, side or rear impacts.
46. 6) To provide a simple and convenient sensor system consisting
of a single discriminating sensor mounted at the CSZ boundary and a
single arming sensor mounted in the passenger compartment for
frontal and/or rear impacts.
47. 7) To provide a sensor which remains closed after it triggers
during a crash.
48. 8) To provide a hermetically sealed crush sensing crash
sensor.
49. 9) To provide a crash sensor which has a hermetically sealed
integral connector thereby eliminating the need for wires to be
connected inside the sensor housing.
50. 10) To provide a crush switch type crash sensor which does not
require a strong mounting structure.
51. 11) To provide a sensor which operates on bending.
52. Preferred embodiments of the invention are described below and
unless specifically noted, it is the applicants' intention that the
words and phrases in the specification and claims be given the
ordinary and accustomed meaning to those of ordinary skill in the
applicable art(s). If applicants intend any other meaning, they
will specifically state they are applying a special meaning to a
word or phrase.
53. Likewise, applicants' use of the word "function" here is not
intended to indicate that the applicants seek to invoke the special
provisions of 35 U.S.C. .sctn.112, sixth paragraph, to define their
invention. To the contrary, if applicants wish to invoke the
provisions of 35 U.S.C..sctn. 112, sixth paragraph, to define their
invention, they will specifically set forth in the claims the
phrases "means for" or "step for" and a function, without also
reciting in that phrase any structure, material or act in support
of the function. Moreover, even if applicants invoke the provisions
of 35 U.S.C. .sctn.112, sixth paragraph, to define their invention,
it is the applicants' intention that their inventions not be
limited to the specific structure, material or acts that are
described in the preferred embodiments herein. Rather, if
applicants claim their inventions by specifically invoking the
provisions of 35 U.S.C. .sctn.112, sixth paragraph, it is
nonetheless their intention to cover and include any and all
structure, materials or acts that perform the claimed function,
along with any and all known or later developed equivalent
structures, materials or acts for performing the claimed
function.
54. In order to achieve one or more of the above objects, a vehicle
crush detecting device in combination with a vehicle in accordance
with the invention comprises a sensor assembly consisting of a
first elongated electrical conductor, a second elongated electrical
conductor, and means for coupling said second electrical conductor
to said first electrical conductor so that said first and second
electrical conductors are parallel and substantially co-extensive
to each other and thereby form the sensor assembly. The coupling
means insulate said second electrical conductor from said first
electrical conductor. Attachment means attach said sensor assembly
to said vehicle at at least two spaced apart positions providing
thereby at least one free, unrestrained span between said at least
two spaced apart locations which is spaced away and not in contact
with any part of said vehicle. In use, when a portion of said
vehicle crushes to contact said sensor assembly in said span
between said at least two spaced apart locations, said sensor
assembly bends in said span between said at least two spaced apart
locations causing said first electrical conductor to contact said
second electrical conductor and complete an electric circuit
indicative of crush of said vehicle. The coupling means may
comprise a header/connector assembly at one end of said sensor
assembly.
55. The first conductor may be a tube which is preferably
deformable and the second conductor may be a rod arranged in said
tube. Insulating means, e.g., round spacers, are positioned at at
least two points between said first and second conductors for
insulating said first conductor from said second conductor. The
spacers extend only at discrete locations circumferentially between
said first and second conductors.
56. The sensor assembly may be attached to said vehicle in a front
region of the vehicle so as to detect crush of the front region of
said vehicle or at a rear of the vehicle so as to detect crush of
the rear of said vehicle. Also, the sensor assembly may be attached
to said vehicle on a side of the vehicle so as to detect crush of
the side of said vehicle. In this case, the sensor assembly can
have an elongate portion attached in a position substantially
parallel to a door panel in a door on said side of said
vehicle.
57. The header/connector assembly hermetically seals a space
between said first and second conductors at one end thereof while
the space between said conductors at the opposite end is closed.
The header/connector assembly includes electrical connector pins
electrically coupled to said first and second conductors and which
have an exposed portion. The header/connector assembly also has a
housing having an inlet port, a dam in the space between said first
and second conductors and urethane or a silicone rubber compound
around the ends of said first and second conductors. Header pins
are connected to said first and second conductors and to the
connector pins.
58. In order to achieve one or more of the above objects, a method
for sealing a device for mounting on an automobile comprises the
steps of providing the device with a cavity having at least one
inlet port and at least one narrow outflow passage, injecting a
curable compound through the at least one inlet port such that the
at least one narrow passage remains open during the injection
process until the cavity is substantially full permitting air
within the cavity to be displaced by the curable compound, the at
least one passage being sufficiently narrow as to permit only a
small amount of rubber compound to flow out of the cavity during
the injection process, but large enough to permit air to easily
flow out of the assembly, and curing the compound.
59. When the device is a crush detecting switch in accordance with
the invention comprising an electrically conductive tube and an
electrically conductive rod arranged within the tube and spaced
therefrom, the cavity is formed at least partially between the tube
and the rod. Also, a plurality of cavities can be formed between
discrete regions of the tube and the rod, separated by means of
spacers, and connected through an aperture in the spacers to enable
the injected curable compound to flow into each of the
cavities.
60. The crush sensing crash sensor of this invention is ideally
adapted for installation at the edge of the CSZ for frontal and
rear impacts of automobiles equipped with one or more inflatable
passenger protective airbags. (Hereinafter, the term "airbag" will
be used to mean all deployable passive passenger protective devices
including airbags, seatbelts with tensioners and deployable nets.)
When the vehicle is subjected to a crash of sufficient magnitude as
to require the deployment of the passive protective device, a
portion of the vehicle is crushed until it contacts the sensor. At
least a portion of the sensor deforms by bending due to the forces
exerted on it by the material contacting it. In a preferred
embodiment, the sensor is constructed from a long rod and a tube
with the rod positioned in the center of the tube by means of
insulating spacers. When the tube bends, it contacts the rod
between the spacers completing a circuit and causing deployment of
the airbag. The rod and tube assembly can be formed in any
convenient geometry, as discussed below, during manufacture so as
to conform to the CSZ boundary of the vehicle. In this manner, the
sensor is placed in the proper position to catch all crashes to the
vehicle for which it was designed regardless of where on the
vehicle the impact takes place.
61. Other embodiments of the vehicle crush detecting device in
accordance with the invention include an electrically conducting,
deformable tube, an electrically conducting rod positioned within
the electrically conducting tube; and insulating means positioned
at at least two points between the rod and the tube to insulate the
rod from the tube. When the tube is deformed or bent by a force
greater than a predetermined magnitude, e.g., by the crush of the
vehicle proximate to or at the location at which the device is
placed, it is forced into contact with the rod.
62. In use as a side impact crush detecting system in order to
deploy an occupant protection apparatus for protecting an occupant
in a side impact, the device is mounted in a position at the side
of the vehicle so as to detect crush of the side of the vehicle and
includes means for coupling the crush detecting device and the
occupant protection apparatus such that upon completion of the
electronic circuit, the occupant protection device is deployed. To
this end, the crush detecting device has an elongate portion
mounted in a position substantially parallel to a door panel in a
door on the side of the vehicle. In another embodiment, the vehicle
crash sensor system comprises a crush detecting switch changeable
from an open position indicative of a non-crush situation and a
closed position indicative of crush of a portion of the vehicle
proximate to the switch; and an electronic sensor coupled to the
crush detecting switch and comprising an accelerometer, and means
coupled to the accelerometer, e.g., a microprocessor having an
algorithm, for initiating deployment of the occupant protection
device based on closure of the crush detecting switch and an
analysis of output from the accelerometer indicative of a situation
in which deployment of the occupant protection device is desired.
The crush detecting switch may comprise an electrically conducting,
deformable tube; an electrically conducting rod positioned within
the electrically conducting tube and insulating means positioned at
at least two points between the rod and the tube to insulate the
rod from the tube. The system may also include means for retaining
the crush detecting switch in the closed position upon change of
the crush detecting switch from the open position to the closed
position.
63. Furthermore, the invention also relates to a method for sealing
a device for mounting on an automobile, e.g., the crush detecting
device, comprising the steps of: assembling the device creating an
enclosed cavity therein, injecting an uncured rubber compound
through at least one inlet port of the cavity in such a manner that
at least one narrow passage leading from the cavity to an exterior
thereof remains open during the injection process until the cavity
is substantially full permitting air within the cavity to be
displaced by the rubber compound; the passage being sufficiently
narrow as to permit only a small amount of rubber compound to flow
out of the assembly during the filling process, but large enough to
permit air to easily flow out of the assembly; and curing the
rubber compound.
64. When the device is a crush detecting switch, it may comprise an
electrically conductive tube and an electrically conductive rod
arranged within the tube and spaced therefrom in which case, the
cavity is formed between the tube and the rod. Also, it is possible
to form a plurality of cavities between discrete regions of the
tube and the rod, separating the cavities by means of spacers, and
connecting the cavities through an aperture in the spacers to
enable the injected uncured rubber compound to flow into each
cavity.
65. Other objects and advantages of the present invention will
become apparent from the following description of the preferred
embodiments taken in conjunction with the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
66. The following drawings are illustrative of embodiments of the
invention and are not meant to limit the scope of the invention as
encompassed by the claims.
67. FIG. 1 is a perspective view of a preferred embodiment of the
sensor of this invention for use in frontal impacts shown removed
from the vehicle.
68. FIG. 2 is a perspective view taken along lines 2--2 of the
sensor shown in FIG. I with the interior parts pulled apart to
illustrate the interior structure.
69. FIG. 3 is a frontal view of another preferred embodiment of the
sensor of shown mounted on a vehicle to sense frontal impacts with
portions of the vehicle removed to permit viewing of the
sensor.
70. FIG. 4A is a view of a vertical segment of the sensor shown in
FIG. 3 taken along line 4--4 in a condition before being impacted
by the vehicle bumper during a crash.
71. FIG. 4B is the same view of the sensor shown in FIG. 4A after
being impacted by the vehicle bumper during a crash.
72. FIG. 5 is a partial view of an alternate configuration of a
vertical portion of the sensor of FIG. 4A showing it displaced
rearward to reduce its sensitivity to impacts above the bumper.
73. FIG. 6 is a view of a vehicle taken from the side, with certain
portions removed, which is about to impact a low pole which misses
the bumper, illustrating the ability of the sensor to respond to
this type of crash.
74. FIG. 7 is a side view of another preferred embodiment of the
sensor in accordance with the invention shown mounted on a vehicle
in a position to sense side impacts, with portions of the vehicle
removed to permit viewing of the sensor.
75. FIG. 8 is a rear view of another preferred embodiment of the
sensor in accordance with the invention shown mounted on a vehicle
in a position to sense rear impacts with portions of the vehicle
removed to permit viewing of the sensor.
76. FIG. 9 is a cutaway view of the header/connector assembly of
FIG. 1, taken along line 9--9, illustrating the construction
details and in particular the method of sealing the sensor.
77. FIG. 10 is a partial cutaway view of a portion of the sensor
illustrating a bend in the sensor.
78. FIG. 11 is a cutaway of the sensor end showing the welded
seal.
79. FIG. 12 is a view of the sensor of FIG. 1 with part of the tube
and rod cut away illustrating the positioning of spacers within the
sensor and their use to change the sensitivity of the sensor to
deformation.
80. FIG. 13 is a circuit schematic showing a side mounted sensor
used as an input to an electronic sensor.
81. FIG. 14 is a view of the sensor of FIG. 1 with portions of the
tube and rod cut away illustrating the use of a grease to fill the
cavity between the rod and tube to minimize the effects of
vibration and to protect the surfaces of the conductors from
corrosion.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
82. Referring to the accompanying drawings wherein like reference
numerals refer to the same or similar elements, the crush switch
sensor constructed in accordance with the teachings of this
invention for use in sensing frontal impacts is shown generally at
101 in FIG. 1. The sensor 101 comprises a unitary, tubular member
having two vertical portions 130 and 131, a lower horizontal
portion 132, two upper horizontal portions 133 and 134 and a
rearward projecting portion 135. The sensor 101 is closed at an end
102 of horizontal portion 134, e.g., by welding, as described below
and a header/connector 103 is attached to the sensor 101 at the end
of portion 135. The sensor 101 is mounted to the front of the
vehicle as shown in FIG. 3 and is constructed of a tube 105 and a
centrally located rod 104 as shown in FIG. 2, which is
substantially coextensive with the tube 105 but normally not in
contact therewith. The sensor 101 functions when it is bent at any
position along the tube 105 with the exception of bent sections or
bends 139 which join the vertical portions 130,131 to the upper
horizontal portions 133,134, respectively, described above and
where plastic spacers 106 prevent the rod 104 from contacting the
tube 105. When the sensor 101 is bent during a crash, the rod 104,
which is made of an electrically conductive material and thus
electrically conducting, contacts the tube 105, which is also made
of an electrically conductive material and thus electrically
conducting, completing an electrical circuit which results in a
deployment of the airbag, i.e., the passive restraint system.
83. The shape of the sensor 101 shown in FIG. 1 is not limiting and
is shown for illustration purposes only. For the same vehicle shown
in FIG. 3, other shapes of sensors may be used and for a vehicle
with a difference front end, the sensor may take any form
sufficient to enable it to perform the desired functions, as
described herein.
84. The rod 104 is maintained in a central location within the tube
105 as illustrated in FIG. 2 by means of the substantially
cylindrical spacers 106 which are placed at each of the bends 139
in the tube 105 and, in one preferred embodiment, in the center of
the lower horizontal portion 132 as shown in FIG. 2. The spacers
106 are made from an electrically non-conductive material, such as
plastic or other suitable flexible material such as rubber, thus
preventing the completion of the electric circuit through the
spacers 106. Although in the preferred embodiment shown in FIG. 1,
spacers 106 are only placed in the bends 139 and at the center of
the horizontal portion 132, in other embodiments, spacers 106 can
be placed arbitrarily along the length of the sensor 101 in order
to adjust the sensitivity of the sensor 101 to particular crash
events. The effect of the spacers 106 is dramatic. The deflection
required to trigger the sensor at the center of the lower
horizontal portion 132 is approximately 0.1 inches if the spacer
106 is not present, and greater than 1 inch if the spacer 106 is
present.
85. Also, the tubular form of the sensor 101 is only a preferred
embodiment, it may have other cross-sectional forms, e.g., oval or
polygonal, depending on the particular need while the spacers 106
similarly are constructed to substantially conform to the interior
shape of the sensor 101. The variable positioning of the spacers
106 provides the advantage of the selective sensitivity of the
sensor 101 to crashes in specific areas along the length of the
sensor 101. As shown, the spacers 106 extend circumferentially
about the rod 104 only at discrete locations in the tube 105 so
that entire circumferential portions of the rod 104 are spaced from
the tube 105.
86. Although spacers 106 are shown to prevent electrical engagement
of the rod 104 and the tube 105, other spacing means may also be
provided to achieve the same function.
87. The crush switch sensor of this invention is shown mounted on a
vehicle in FIG. 3 where a substantial portion of the vehicle has
been removed to better illustrate how the sensor 101 is mounted. In
the configuration in FIG. 3, the rearward portion 135 of the sensor
101 has been eliminated and the sensor 101 extends only toward the
outside of the vehicle. The vehicle structure shown consists of an
upper radiator support 120, two vertical radiator supports 122 and
123 and a lower radiator support 132. The two vertical radiator
supports 122,123 and the lower radiator support 132 are attached to
rails 140 which are the structures of the vehicle which support the
front end. A bumper structure 112 (of a particular vehicle) but not
the bumper plastic cover is also illustrated in FIG. 3. The crush
switch sensor 101 in accordance with the invention is attached to
the upper radiator support 120 by attachment means, e.g.,
conventional hardware 108 and 109, and to the lower radiator
support 132 by attachment means, e.g., conventional hardware 110
and 111. Hardware elements 108,109,110,111 are clamps having two
holes for enabling a screw or nail to connect the clamps to the
radiator supports. Obviously, any attachment means are suitable for
these purposes.
88. During a frontal impact with either a barrier or another
vehicle, for example, bumper structure 112 is displaced toward the
rear of the vehicle relative to the radiator supports of the
vehicle to a position where it impacts the vertical portions 130
and 131, of the crush switch sensor 101, which are mounted so as to
be spaced away by attachments 108-111 and thereby not in contact
with the vehicle. This sequence is illustrated in FIGS. 4A and 4B
which are views taken along lines 4--4 of FIG. 3. Upon impact with
sensor vertical portion 131, bumper structure 112 causes the rod
and tube assembly of sensor 101, and at least vertical portions
130,131, to bend which in turn causes the rod 104 to contact the
inside of the tube 105, at locations 161, 162, 163, and 164,
completing the electrical circuit and causing deployment of the
airbag. Although in this case four contacts are made between the
rod and the tube, only one is necessary to cause completion of an
electric circuit and thus, e.g., deployment of the airbag. In this
manner, any crash which causes the bumper structure 112 to be
displaced toward the rear of the vehicle will cause the sensor 101
to trigger by means of the completion of an electric circuit
between the rod 104 and the inside surface of the tube 105.
89. A key advantage of the sensor in accordance with this invention
is that it operates on bending. During a crash, the impact to a
particular point in or on the vehicle cannot be guaranteed but the
fact that a line across the front, side or rear of the vehicle will
not remain straight can almost assuredly be guaranteed. Therefore a
sensor which is long and narrow and responds to bending will be
highly reliable in triggering on even the most unusual crashes. The
inventive sensor can be designed to cover a significant distance
across the vehicle which increases the probability that it will be
struck by crushed material and bent as the crush zone propagates in
the vehicle during a crash. At the same time, the sensor 101 is
small so that it can be located in a position to sense the fact
that one part of the vehicle has moved relative to some other part
or that the structure on which the sensor 101 is mounted has
deformed. In this regard, sensor 101 may be positioned at the rear
of the CSZ of the vehicle.
90. Not all crashes involve the bumper and in a survey of crashed
vehicles (see SAE paper No. 930650), as many as 30% of the surveyed
vehicles were involved in crashes where the bumper was not
primarily involved. A typical crash of this type involves a vehicle
which is braking and therefore pitching forward which lowers the
front bumper and raises the rear bumper. If this first vehicle is
struck in the rear by another second vehicle which is similarly
pitching, the second striking vehicle will impact the first struck
vehicle with the front bumper of the second striking vehicle riding
underneath the rear bumper of the first struck vehicle. In this
case, the bumper of the first struck vehicle will impact the grill
and radiator of the second striking vehicle and displace the
vertical portions 130 and 131 of the crush switch sensor in
accordance with this invention. As such, the electric circuit is
completed and airbag deployment is initiated.
91. When the bumper structure 112 is involved in an accident, it
generally maintains its structural shape until it begins impacting
the radiator and other structures behind the radiator. This is
after it has impacted the sensor 101. Since the bumper structure
112 has not yet deformed when it strikes the sensor 101, the sensor
101 triggers on a crush of the vehicle equivalent to the distance
between the rear of the bumper structure 112 and the sensor 101,
plus the amount of sensor deflection required to trigger. If the
bumper structure 112 is not primarily involved in the accident, the
amount of penetration into the vehicle required to trigger the
sensor 101, measured from the front of the bumper structure 112,
will be greater by the amount of the thickness of the bumper
structure 112. In this manner, the sensor system requires greater
penetration into the vehicle in bumper underride crashes. This
results in a longer time to trigger which is desired since such
crashes are softer than those crashes which involve the bumper and
therefore there is more time available before deployment of the
airbag is required.
92. In some cases, it is necessary to further desensitize the
sensor to bumper underride type crashes to make the sensor less
sensitive to deer impacts, for example. Every year in the United
States there are approximately 300,000 impacts with deer and in
most cases airbag deployment is not needed. Currently used sensor
systems, however, can cause the airbag to deploy on deer impacts.
When impacted at high speeds, the crash pulse in the non-crush zone
can be similar to the crash pulse from a barrier crash up to the
time that the decision must be made to deploy the airbag. In such
cases, electronic sensors operating on the non-crush zone crash
pulse will determine that the airbag deployment is required.
Currently used crush zone sensors are typically mounted above the
bumper and project outward from brackets attached to the upper
radiator support. These sensors are impacted by a deer even at
lower speeds and experience a velocity change sufficient to cause
deployment of the airbag.
93. The crush switch sensor in accordance with the invention,
however, can be desensitized in a manner such as shown in FIG. 5 so
as to render it insensitive to deer impacts (or impacts with other
large animals). In this case, a section designated at 138, of at
least the vertical portion 130, of the sensor 101 has been
displaced rearward to render it less sensitive to deer impacts.
Section 138 is substantially U-shaped. Vertical portion 130 and
horizontal portion 132 can also be constructed with a rearwardly
displaced portion to thereby enable adjustment in the degree of
sensitivity of the sensor 101.
94. Approximately 2% of frontal crashes involve impacts to the
vehicle below the bumper. In a typical case, a vehicle impacts with
a large stone, tree stump or short or low pole which miss the
bumper. This type of accident is expected to become more common
since in order to make vehicles more aerodynamic, vehicle hoods
have been made lower and the radiators have also been lowered until
as much as one-third of the radiator now projects below the lower
edge of the bumper. An impact with a short pole or curb 202 such as
shown in FIG. 6 where the pole interacts with the lower portion of
the radiator, can result in an airbag required crash which will not
be properly sensed by current sensor technology, e.g., ball-in-tube
crush zone sensors. The ball-in-tube crush zone sensors are
typically mounted above the bumper and therefore would not be in
the crush zone for this kind of a crash causing them to trigger on
the non-crush zone crash pulse resulting in a late deployment of
the airbag. The preferred embodiment of the crush switch sensor of
this invention shown in FIG. 6, on the other hand, stretches across
the front of the vehicle and will trigger thereby causing the
airbag to deploy in time for these crashes.
95. About the most common of all real-world airbag crashes involve
impacts with poles. Pole impacts are some of the most difficult
crashes to sense properly with current airbag sensor technology.
Poles that can require airbag deployment vary in diameter from as
little as about 4 inches to greater than about 24 inches. They
involve such objects as fence posts, light poles, trees and
telephone poles which are the most common obstacles found along the
sides of roads. An impact into a pole at any position along the
front of the vehicle can result in a serious accident requiring
deployment of the airbag. The stiffness of the vehicle, however,
varies significantly from one part of the front to the other. For
most vehicles, the center front is the softest part of the vehicle,
and the rails are the stiffest. In a typical accident, the bumper
will buckle around a pole resulting in a soft crash pulse until the
pole penetrates sufficiently into the vehicle that it begins to
engage major structural members or the engine at which time, the
pulse becomes very stiff. This type of crash pulse is particularly
difficult for non-crush zone sensors to sense properly.
96. Pole crashes are typically staged by automobile manufacturers
during their airbag development .programs, but they are limited in
scope. They typically involve large poles that are one foot or more
in diameter and are usually run at high speeds. It has been found,
however, that thin poles at low speeds are much more difficult to
enable proper sensing for airbag deployment than thick poles at
high speeds. Non-crush zone sensors have a particularly difficult
time in sensing pole crashes especially those involving thin poles
at low velocities, since the crash pulse is very soft until it is
too late to initiate airbag deployment. Conventional crush zone
sensors, such as the ball-in-tube sensor, function properly as long
as the sensor is located in-line with the impact point of the pole.
When this is not the case, and especially when the impact speed is
low, ball-in-tube sensors can fail. A particular case, for example,
involved a vehicle which has three ball-in-tube sensors mounted in
the crush zone, one center mounted and one on each side
approximately in line with the rails. This vehicle impacted a pole
at approximately 15 miles per hour at a point midway between the
front and side sensors. An examination of the vehicle showed that
there was no crush at either of the sensor locations. In this case,
the sensor triggered the airbag late based on the non-crush zone
crash pulse as described in U.S. Pat. No. 4,900,880 (Breed)
referenced above. Before the airbag deployed, the occupant had
already impacted with the steering wheel and although conscious
after the accident, later died from internal injuries. The crush
switch disclosed here, in the embodiment illustrated in FIG. 3,
would have triggered in time for this and all other pole impacts
since it stretches substantially across the entire front of the
vehicle, i.e., from one side to the opposite side. Of course, the
sensor 101 can stretch across only a portion of the front of the
vehicle in which case, it would be beneficial but not required to
use multiple sensors.
97. In a small but significant percentage of automobile crashes
(less than 2%), the point of impact is outside of the main vehicle
supporting structure which is typically the rails. In a common
accident, a vehicle impacts a pole at approximately the location of
the headlights at a slight angle and the pole penetrates into the
vehicle with little resistance until it encounters the front wheel
structure at which point the vehicle rapidly stops. This crash
cannot be properly sensed by most, if not all, conventional airbag
sensor system in use today. Electronic sensors will either trigger
late or not at all due to the very soft nature of this crash up to
the point where the pole impacts the wheel structure which is too
late. Some conventional crush zone sensors are usually mounted
inside of the rail structure and thus are not in the crush zone for
this crash, which is usually exterior of the rail structure. They
also, therefore, would either not trigger or trigger late. The
crush switch sensor of this invention as shown in FIG. 3 projects
only slightly beyond the rail structure and therefore could also
miss this type of crash. The extension of the upper horizontal
portions 133 and 134, however, will permit the crush sensor to
trigger on this type of crash. These extensions would trigger the
deployment of the airbag in this pole crash and other airbag
desired crashes outside of the rail structure. This crash is, as
mentioned, a soft crash and therefore there will be substantial
penetration before the sensor must trigger. The upper horizontal
portions 133 and 134 therefore could be angled toward the rear in
the vehicle to adjust the penetration required for the sensor to
trigger.
98. In order for current technology crush zone sensors to sense
crashes outside of the rails in time, additional sensors would have
to be placed outboard of the rails. As mentioned above, even three
sensors are insufficient to catch all pole crashes to the front of
the vehicle and when bumper override crashes are considered, such
as the low pole crash described above, additional sensors are
required. A primary advantage of the crush switch sensor of this
invention is that a single sensor can be used to sense crashes to
all portions of the front of the vehicle. To achieve the equivalent
coverage using conventional sensors would require at least five and
probably more sensors. The manufacturing cost of a sensor described
in this invention is about equivalent to the manufacturing cost of
a single ball-in-tube crush zone sensor. Therefore, in addition to
the substantial performance advantage, there is also a substantial
cost advantage in using the sensor described herein.
99. In addition, a significant cost in a sensor system is the cost
of the wires to connect each sensor to the remainder of the airbag
system. It is typical for a wire and connector assembly plus the
cost of insulation to be as much as half of the cost of the sensor
itself. In the sensor described herein, a single wire assembly is
all that is required to connect the sensor to the airbag system. It
would also be possible to wirelessly connect the sensor assembly to
the airbag system. With conventional crush zone sensors, a separate
wire assembly is needed for each sensor. Finally, in order to
minimize the possibility of the conventional crush zone sensor from
rotating during angle crashes, for example, the mounting structure,
typically the upper radiator support, is frequently strengthened to
provide a more rigid mounting structure for the sensor. This
modification to the vehicle structure is not required for the
sensor described herein and therefore additional cost savings
result.
100. As discussed above, and in several of the cited references on
sensing side impacts, crush sensing alone is not the best technical
solution for sensing side impacts. In spite of this fact, Volvo is
now marketing a side impact airbag protection system where the
sensor is a crush sensing sensor, although it is a point sensor and
not a rod-in-tube geometry. In the event that other automobile
manufacturers choose this approach, the rod-in-tube crush sensor
described herein can be used as shown in FIG. 7 which is a side
view of the sensor of this invention shown mounted on a vehicle to
sense side impacts. One advantage of the rod-in-tube sensor is that
it can cover a large area of potential crash sites at little
additional cost. Thus, a single sensor can stretch along the entire
door in whatever shape desired, e.g., linearly as shown at 300 in a
position substantially parallel to the door panel. Thus, the sensor
300 would trigger upon impact at any location along the door. This
solves a potential problem with the Volvo system which requires
that the crash take place at a particular location for the airbag
to be deployed.
101. In addition, sensors could extend across the side panels of
the vehicle and not only across the doors.
102. The use of a rod-in-tube sensor for side impacts as well as
one for frontal impacts is particularly attractive since it can be
easily attached to the same diagnostic module. Thus, the same
Diagnostic and Energy Reserve Module (DERM) can be used for
frontal, side and even rear impacts. A particularly economic system
results if these sensors are used for the entire vehicle providing
a simple electronic diagnostic system is used in contrast to the
complicated microprocessor based systems now in use. Thus, superior
protection for the entire vehicle for crashes from any direction
can be obtained at a substantial cost reduction over the currently
used electronic systems.
103. Some of the objections for its use for side impact are
partially overcome by placing the sensor sufficiently inboard from
the outer portion of the vehicle as to require substantial crush of
the door before the sensor is initiated. This, of course, delays
firing of the airbag system and requires that the inflator inflate
the airbag in a shorter period in order to make up for the loss of
sensing time.
104. The sensor of this invention can also be used as a safing
sensor for side impacts. In this case, it is used in combination
with a velocity change sensor such as the electromechanical sensor
having a moving mass described in U.S. Pat. No. 5,231,253
referenced above and incorporated herein by reference. This imposes
the dual requirement that velocity change plus vehicle crush both
occur before the airbag deploys. It is referred here as a safing
sensor since if it is mounted near the outer door skin, it will
trigger on a very low velocity change such as one or two miles per
hour as is the case for conventional safing sensors used in frontal
impacts.
105. Finally, the use of the sensor of this invention in
conjunction with an electronic sensor for side impacts will be
discussed in more detail below.
106. The application of the sensor of this invention for rear
impacts is in theory similar to that for frontal impacts. In
contrast to frontal impact, there is not yet universal agreement as
to the velocity change at which the deployment of a
headrest-mounted airbag is needed. Many whiplash injuries occur at
very low velocity changes, as low as about 5 mph. The replacement
cost for such an airbag will be substantially less than for frontal
impact airbags consequently again the deployment velocity could be
made lower. On the other hand, if the headrest is properly
positioned, only high velocity impacts would require airbag
deployment. It is important to keep in mind that whiplash injuries
are the most expensive group of automobile injuries even though
they are usually not life threatening.
107. The choice of the marginal deployment velocity significantly
impacts the location of the rod-in-tube sensor of this invention.
Also, the rear end sections of automobiles differ substantially in
their structure, stiffness, and suitable sensor mounting locations.
In some vehicles the optimal sensor mounting location will be in
the trunk lid. In others, especially if low velocity impacts are to
the sensed, a location behind the bumper is appropriate. In many
vehicles, the proper location is in the middle of the trunk volume,
an impractical place to mount any sensor. For these vehicles, the
sensor is designed to extend around on three sides of the trunk and
desensitized through the use of spacers so that substantial
deformation is required to trigger the sensor.
108. Due to this wide variability in sensor strategies and
resulting sensor locations and geometries, FIG. 8 illustrates a
general sensor 310 arbitrarily mounted to the rear of the vehicle
to sense rear impacts, and as shown, in a position extending across
substantially the entire width of the rear of the vehicle. Portions
of the vehicle are removed to permit viewing of the sensor. The
determination of the proper mounting position and sensor design
follows the same strategy illustrated above and in the cited
references.
109. The environment experienced by a sensor mounted in the front
of the radiator on a vehicle is one of the most severe in the
automobile. In addition to the extremes of temperature encountered
between winter in Alaska and summer in the Arizona desert, this
location is impacted by hail, stones, dust, dirt, salt water,
radiator coolant, steam cleaner and occasionally even battery acid.
This sensor must be capable of surviving any combination of these
environments for the useful life of the car which is typically
considered to be in excess of ten years. It is important,
therefore, that this sensor be hermetically sealed. A great deal of
effort has been put into the current ball-in-tube crush zone sensor
to seal it from these environmental influences. Nevertheless,
sensors that have been on vehicles have been dissembled and found
to contain moisture. Although moisture would not have as
detrimental effect to the rod-in-tube sensor described here as it
does to ball-in-tube sensors, the sensor has nevertheless been
designed to be truly hermetically sealed as described below.
110. FIG. 9 is a cross section view of the header/connector
assembly 103 shown mounted on the tube 105 and rod 104. One of the
spacers 106 is used to position the rod 104 inside the tube 105 as
described above. The primary seal for this sensor 101 is injected
and cured in place and is urethane or a silicone rubber compound
301.
111. Current ball-in-tube crush zone sensors are attached to the
vehicle wire harness and, thus to the remainder of the airbag
system, by means of a pigtail which is a wire assembly emanating
from the sensor at one end and having a connector at the other end.
It is believed that the environment in front of the radiator is too
severe for connectors, therefore connectors integral with the
sensor have not been considered. This pigtail is one of the most
expensive parts of the standard ball-in-tube crush zone sensor.
Substantial cost savings result if the connector could be made
integral with the sensor. This has been accomplished in the crush
switch sensor of the current design as shown in FIGS. 1, 3 and
9.
112. The sealing technique used for the header/connector is to form
a rubber mold within the housing and to pump a rubbery material
such as urethane or silicone rubber, or similar compound, 301 into
the cavity. This is accomplished in such a manner that the air is
displaced and forced to flow through various clearances between the
parts in much the same manner as air is forced out of a plastic
injection mold when the liquid plastic is forced in under pressure.
The rubber compound 301 is injected through hole 302 in the bottom
of the connector portion of the assembly and flows upward as the
air flows out through holes or slots 315 in tube 105 and finally
out of the assembly through the clearance between the tube 105 and
a plastic dam 313. The plastic dam 313 is a part which fits snugly
to the tube and also against a plastic header body 310 of the
header/connector assembly 103. These snug fits permit the air to
flow while offering a substantial resistance to the flow of the
rubber 301. In this manner and through the proper geometric shaping
of the various parts, all but a few minute air bubbles are
effectively removed and the rubber thereby attaches and seals to
all of the relevant surfaces.
113. A second dam 312 is also used to limit the passage of the
rubber into the main body of the sensor 101. The spacers 106
typically contain a groove to permit the passage of grease, as will
be explained below, and the dam 312 effectively seals this area and
prevents passage of the rubber. Since the grease is typically
pumped into the sensor 101 after the header/connector assembly 103
is assembled, this last spacer 106 adjacent to the header/connector
assembly 103 need not have the groove and thus the dam 312 and
spacer 106 can be made as one part if desired.
114. The seal is thus made by the steps of:
115. a) assembling the header/connector assembly 103 to the
rod-in-tube assembly 104/105 creating at least one enclosed cavity
therein having at least one inlet port 302 for injecting a rubber
compound and at least one narrow passage for air to escape (the
clearance between tube 105 and dam 313), this passage being
sufficiently narrow as to permit only a small amount of rubber
compound to flow out of the assembly during the filling process,
but large enough to permit air to easily flow out of the
assembly;
116. b) injecting an uncured rubber compound through the inlet
port(s) in such a manner that the at least one narrow passage
remains open during the injection process until the cavity is
substantially filled permitting air within the cavity to be
displaced by the rubber compound; and
117. c) curing the rubber compound.
118. Usually a room temperature curing rubber compound is used and
thus the curing process comprises storing the assembly until the
curing is complete. In many cases, the temperature of the assembly
is elevated to accelerate the curing process and in others, the
rubber is exposed of ultra violet light to effect the cure.
119. Tests were run on this system whereby the assembly was held at
about -40 degrees Celsius for at least twelve hours and then
immersed into boiling water and then into near freezing water
containing a penetrating die. After tens of cycles, the test units
were cut open to search for the penetration of the die which would
indicate a failure of the seal. None was found. In contrast, a
commercially available ball-in-tube sensor failed on the first
cycle. This test is more severe than any sensor is likely to
experience in the field and therefore proves the viability of the
sealing system.
120. A preferred plastic material used for the header/connector is
30% glass filled polyester although other plastic materials would
work as well. Standard crush zone sensor connectors are frequently
made from unfilled Nylon and this would also be suitable for the
header/connector design used in the sensor of this invention.
Although unfilled Nylon has a high coefficient of thermal
expansion, the urethane or silicone rubber has even a higher one
and therefore the seals between the nylon and metal parts will
remain intact.
121. The lower portion 326 of the header/connector assembly 103
shown in FIG. 9, is in the form of a mating connector which
attaches to the wire harness connector provided by the automobile
manufacturer. Connector pins 305 and 306 are extensions of the
header pins 303 and 304, which are connected to the rod 104 and
tube 105, respectively, and are designed to mate with the
appropriate connector, although not shown in detail here. Connector
pins 305 and 306 are made of an electrically conductive material.
Upon completion of the circuit via contact between the rod 104 and
the tube 105 upon a crash, current flows through the connectors
305,306, header pins 303,304 and rod 104 and tube 105. The header
pins 303,304 are formed from, e.g., sheet brass, in such a manner
that they surround the rod 104 and tube 105 and are electrically
connected thereto. This is accomplished in the case of the tube,
for example, by solder coating the end 322 of the tube 105. A
mating portion 308 of the header pin 304 fits snugly inside the
tube and, through induction heating, is soldered to the tube.
Similarly, mating portion 307 of header pin 303 surrounds the rod
104 which has been soldered coated at its end 311.
122. The header pins 303 and 304 are first formed from, e.g.,
tin-plated brass material, to the proper shape and then placed in a
mold in an insert molding operation to form the header/connector
assembly 103.
123. Spacers 106, in addition to their use in a straight portion of
the rod and tube assembly as shown in FIG. 2, are also placed in
each of the bends 139. A partial cutaway view of a typical bend 139
is shown in FIG. 10. During assembly the spacers are placed on the
rod and the rod is inserted into a straight tube with the spacers
106 located at each position where the tube will be bent. The tube
is then bent at spacer locations using conventional tubing benders
and the rod is also forced to bend by virtue of the spacer. The
spacers are formed from extruded plastic tubing and are slightly
smaller in diameter than the tube. The internal diameter of the
spacer, however, is such as to require a press fit onto the rod.
Thus, the spacers 106 are held firmly on the rod 104 as the rod 104
is inserted into the tube 105. Spacers used in the bends are
typically about 3 inches long when used with a 0.5 inch tube and a
one inch bend radius.
124. In a typical large tube assembly, the tube outside diameter is
approximately 0.5 inch and the wall thickness approximately 0.035
inches and in a small tube assembly the outside diameter is
approximately 0.25 inches and the wall thickness is about 0.02
inches. The large tube design is used when there is no convenient
structure to mount the sensor against and it is vulnerable to
abuse, while the thin or small tube design is used when it can be
mounted nearly flush against the radiator support, for example, or
in a protected location such as inside of the vehicle door.
125. The end 102 of the sensor 101 which does not have the
header/connector 103 is welded closed as shown in FIG. 11. Some
vehicle manufacturers require a diagnostic resistor to be placed
across the contacts in the sensor 101. This is accomplished as
shown in FIG. 11 by attaching a resistor 180 to an end 141 of rod
104 and to an end 142 of tube 105. The end 142 is formed by
squeezing the tube in the appropriate set of dies which gradually
taper and flatten the tube, squeezing the end of resistor 180 and
closing off the tube with a straight line seal. The end of this
seal, 143, is then TIG welded using conventional equipment to
assure a hermetic seal.
126. FIG. 12 is a view of the sensor of FIG. 1, with half of the
tube 105 and rod 104 removed but showing complete spacers 106,
taken along lines 12--12 and showing the location of all of the
spacers 106 and the rod 104 and tube 105.
127. If the passenger compartment discriminating sensor is of the
electronic type, the triggering threshold can be changed based on
the condition of the crush switch sensor in the crush zone.
Passenger compartment sensors sometimes trigger late on soft long
duration frontal crashes even though the velocity change is
significantly higher than the desired deployment threshold(see, for
example, reference 4 above). In such a case, the fact that the
crush switch sensor has triggered can be used to modify the
velocity change required for the electronic sensor to trigger.
Thus, in one case, the passenger compartment sensor can prevent the
deployment of the air bag when the velocity change is too low as in
the animal impact situation discussed above and in the second case,
the crush zone sensor can cause the discriminating sensor to
trigger faster in a soft crash and minimize the chance of a late
triggering condition where the occupant is out of position and in
danger of being injured by the deploying air bag.
128. FIG. 13 shows schematically such a circuit applied to side
impacts where an electronic sensor 411 triggers deployment of the
side airbag resident in a side airbag module and crush sensor 410
is used as input to the electronic sensor 411. In this case, the
current carrying capacity of the crush sensor 410 can be much less
and thinner wires can be used to connect it to the electronic
sensor 411. In one scenario, the electronic sensor may be
monitoring an event in progress when suddenly the crush sensor
signals that the vehicle has crushed to where the sensor is
mounted. The electronic sensor 411 now uses this information along
with the acceleration signal which it has been monitoring to
determine the magnitude of the crash. The crush sensor 410 informs
the electronic sensor 411 that a crash is in progress and the
electronic sensor 411, which comprises an accelerometer and a
microprocessor with a crash analysis algorithm, determines the
severity of the crash based on the acceleration signal. If the
acceleration signal is present but the crush sensor 410 fails to
record that a crash is in progress then the electronic sensor 411
knows that the acceleration signal is from either a non-crash event
or from a crash to some part of the vehicle, such as in front of
the A-pillar or behind the C-pillar where deployment of the airbag
is not warranted. The A-pillar is the foremost roof support member
on which the front doors are hinged and the C-pillar is the
rearmost roof support pillar usually at or behind the rear
seat.
129. An example of an electronic crash sensor algorithm can be
found in patent application to D. S. Breed titled "Method and
Apparatus for Sensing a Vehicle Crash," Ser. No. 08/476,076, filed
Jun. 7, 1995.
130. A typical length of the span between spacers for the vertical
portions 130 and 131 of FIG. 1 is approximately 10-15 inches. In
this configuration, the rod 104 will actually deflect and contact
the tube during minor accidents and therefore in the preferred
embodiment of the design, the tube is filled with a damping
material which is typically a viscous liquid or grease which has
been formulated to operate over the required temperature range of
from about -40.degree. C. to 125.degree. C. For the purposes of
this disclosure, the term grease will be used to include all
flowable materials having a viscosity between 100 and 100 million
centipoise. This would include, therefore, all silicone and
petroleum and other natural and synthetic oils and greases in this
viscosity range. This grease 600 is shown in FIG. 14 where half of
the tube 105 has been removed to show the grease 600 filling
substantially the entire tube. Small voids 601 are intentionally
placed in the grease to allow for differential expansion between
the grease and the tube due to variations in temperature. When
grease is used, small channels, not shown, are provided in the
spacers 106 to permit the grease to flow past the spacers as the
sensor is pumped fall of the grease.
131. The sensor described and illustrated above is designed to
catch all impacts to the vehicle regardless of where they occur
providing the sensors are properly located. For frontal and rear
impacts the severity of the crash required to cause sensor
triggering is determined by the amount of crush of the vehicle at
each location which is necessary to cause the sensor to close. The
amount of crush necessary to trigger the sensor at any location can
be varied arbitrarily by the distance the sensor is located from
the front or rear of the vehicle, by the location and
characteristics of spacers in the sensor and by the location and
characteristics of the supports that are used as discussed
above.
132. Steel has been used for the materials for the rod and tube for
the preferred embodiment described herein. The tube is in an
annealed state to promote easy forming to the required shape and to
promote deformation during the crash. The rod, on the other hand,
is typically hardened so as to maintain its spring temper and
promote good contact forces with the tube when the combination is
bent. The outside of the sensor is coated with a protective coating
to prevent it from rusting during the estimated 10 year life of the
vehicle. The interior surfaces are coated with grease to prevent
corrosion in those cases where the entire sensor in not filled with
grease. Naturally, other materials such as aluminum, brass or even
plastic with an electrically conductive surface coating could be
used for the rod and tube.
133. The rod and tube described above, for the large tube design,
have been designed to require approximately fifty to one hundred
pounds of force in order to cause the sensor to trigger. This is to
minimize the chance of inadvertent deployment during routine
vehicle maintenance. For cases where the sensor is in a protected
location, the small tube design typically uses about a 0.25 inch
diameter tube with about a 0.0625 inch diameter rod.
134. Once the crush switch of the present design triggers it
remains latched in the conductive state for the duration of the
crash. This important feature as discussed in detail in the above
referenced patent applications, guarantees overlap between the
triggering of the crush zone sensor and the passenger compartment
mounted arming sensor when used for frontal and rear impacts.
135. The sensor described and illustrated herein utilizes a
diagnostic resistor. Other systems require a complete monitoring of
the sensor without the use of a diagnostic resistor. This can be
accommodated in the present design by using header/connectors on
both ends of the sensor. In this case, diagnostic currents could
pass through both the rod and the tube independently permitting
small changes in the total resistance of the entire circuit to be
diagnosed.
136. The tube of the sensor described herein is usually
electrically grounded to the vehicle. In some applications, it may
be desirable not to ground the outside of the tube in which case
the tube would be surrounded by an insulating plastic tube. The use
of a grounded outer tube has the advantage of providing shielding
from electromagnetic radiation for the rod and thus minimizing the
chance of an inadvertent signal reaching the electronic sensor, for
example, as the vehicle passes through strong electromagnetic
fields.
137. A primary advantage of the sensor described herein is its
coaxial design which permits arbitrarily shaping of the sensor to
adapt the sensor to a particular vehicle and to a particular place
on that vehicle. There are, of course, other designs which could
also be arbitrarily shaped including, but not limited to, tubes
having a square, elliptical or triangular cross section. All of
these and similar geometries are considered tubes for the purpose
of this invention. Similarly, the rod can take on a variety of
shapes without departing from the teachings of this invention. In
particular, the rod can also be a tube which has advantages in
minimizing the effects of vibration. The rod need not be round and
can be triangular, elliptical, square or even ribbon shaped. All of
these geometries are considered rods for the purposes of this
invention.
138. Another key feature of this invention is that, when the sensor
is properly mounted on the vehicle, plastic deformation of the tube
generally occurs prior to triggering of the sensor and always
occurs in a crash where the deployment of the airbag is required.
As discussed above, this results in the sensor latching closed
during the crash but is also prevents it from being reused on the
same or another vehicle. In an alternate configuration, the
dimensions of the rod and tube and the material properties are
chosen so that the sensor can be caused to trigger with sufficient
force without causing plastic deformation. This permits manual
testing of the sensor after it is mounted on the vehicle as desired
by some vehicle manufacturers. In most embodiments, the sensor can
be made to trigger prior to mounting onto the vehicle by manual
bending without plastic deformation. This permits the sensor to be
tested after it has been manufactured but before mounting onto the
vehicle.
139. The use of grease to dampen the motion of one or more of the
parts of a crash sensor has been disclosed herein. Other crash
sensor designs, and particularly crush switch sensor designs, could
also make use of a grease to surround and dampen the motion of one
or more of the internal parts of the sensor.
140. The hermetic sealing system disclosed herein has permitted the
first use of an integral header/connector thus eliminating the need
for the pigtail and substantially reducing the cost of airbag
sensors for frontal mounting in the "splash zone". Naturally, now
that this system has been disclosed other applications of this
system to other types of crash sensors will become obvious to those
skilled in the art.
141. If two sensors of the type disclosed in this invention are
mounted on a vehicle with one closer to the front than the other,
then, during a crash, the forwardmost sensor will trigger first
followed by the second more rearward sensor. If the spacing between
the sensors is known, an estimate of the crash velocity can be
obtained by measuring the time between switch closures. In this
manner, the use of two switches can be used to determine the crash
velocity.
142. There has thus been shown and described an improved
rod-in-tube crush switch crash sensor which fulfills all the
objects and advantages sought after.
143. More particularly, disclosed above is a vehicle crush
detecting device in combination with a vehicle comprising an
electrically conducting, deformable tube, an electrically
conducting rod positioned within the tube, insulating means
positioned at at least two points between the rod and the tube for
insulating the rod from the tube and attachment means for attaching
the tube to the vehicle at at least two spaced apart locations to
provide at least one free, unrestrained span of the tube between
the at least two spaced apart locations which is spaced away and
not in contact with any portion of the vehicle. When the tube is
deformed by a force greater than a predetermined magnitude during
crush of the vehicle, the tube contacts the rod in response to the
crush of the vehicle thereby completing an electric circuit
indicative of crushing of the vehicle. Contact of the rod by the
tube may be caused by bending of the tube. The rod and tube in the
sensor may be unitary and the rod may substantially solid. The
insulating means may comprise spacers extending circumferentially
about the rod only at discrete locations in the tube.
144. Mounting means may be provided for mounting the crush
detecting device in a front region of the vehicle so as to detect
crush of the front region of the vehicle or in a rear of the
vehicle so as to detect crush of the rear of the vehicle. If the
vehicle includes a deployable occupant protection apparatus for
protecting an occupant in a side impact, mounting means may be
provided for mounting the crush detecting device in a side of the
vehicle so as to detect crush of the side of the vehicle. Also, the
crush detecting device is coupled to the occupant protection
apparatus such that upon completion of the electronic circuit, the
occupant protection device is deployed. An electromechanical sensor
having a moving mass or an electronic sensor coupled to the crush
detecting switch. The crush detecting device may have an elongate
portion mounted by the mounting means in a position substantially
parallel to a door panel in a door on the side of the vehicle.
145. In another embodiment of the invention disclosed above, the
vehicle crush detecting device in combination with a vehicle
comprising an electrically conducting, deformable tube containing
grease, an electrically conducting rod positioned within the tube
and insulating means positioned at at least two points between the
rod and the tube for insulating the rod from the tube. When the
tube is deformed by a force greater than a predetermined magnitude
during crush of the vehicle, it contacts the rod thereby completing
an electric circuit indicative of crushing of the vehicle. The tube
is not completely filled with grease such that voids are present in
the tube to allow for differential expansion between the grease and
the tube.
146. In another embodiment of the invention disclosed above, a
vehicle crash sensor system comprises a crush detecting switch
changeable from an open position indicative of a non-crush
situation and a closed position indicative of crush of a portion of
the vehicle proximate to the switch, an electronic sensor coupled
to the crush detecting switch and comprising an accelerometer, and
means coupled to the accelerometer for initiating deployment of the
occupant protection device based on closure of the crush detecting
switch and an analysis of output from the accelerometer indicative
of a situation in which deployment of the occupant protection
device is desired. Means are provided for retaining the crush
detecting switch in the closed position upon change of the crush
detecting switch from the open position to the closed position. The
crush detecting switch may be mounted on a side of the vehicle so
as to detect crush of the side of the vehicle.
147. In another embodiment of the invention disclosed above, a
vehicle crush detecting device in combination with a vehicle
comprises an elongate, electrically conducting, deformable tube,
the tube having an inner circumferential surface and an outer
circumferential surface, an elongate, electrically conducting rod
positioned within the tube and having an outer circumferential
surface, attachment means for attaching the tube to the vehicle at
at least two spaced apart locations to provide at least one free,
unrestrained span of the tube between the at least two spaced apart
locations which is spaced away and not in contact with any portion
of the vehicle and insulating means positioned at at least two
longitudinal points between the rod and the tube for insulating the
rod from the tube, the insulating means being arranged to separate
the entire outer circumferential surface of the rod from the entire
inner circumferential surface of the tube around the entire outer
circumference of the rod. As such, the tube is deformable by the
crush of the vehicle about its entire circumference into contact
with the rod. When the tube is deformed by a force greater than a
predetermined magnitude during crush of the vehicle, it contacts
the rod thereby completing an electric circuit indicative of
crushing of the vehicle.
148. Many changes, modifications, variations and other uses and
applications of the subject invention will, however, become
apparent to those skilled in the art after considering this
specification and the accompanying drawings which disclose the
preferred embodiments thereof. All such changes, modifications,
variations and other uses and applications which do not depart from
the spirit and scope of the invention are deemed to be covered by
the invention which is limited only by the following claims.
* * * * *