Electrical transmission or interconnection systems – Vehicle mounted systems – Automobile
Reexamination Certificate
2000-12-20
2003-05-06
Sircus, Brian (Department: 2836)
Electrical transmission or interconnection systems
Vehicle mounted systems
Automobile
C701S045000, C180S282000, C280S728100
Reexamination Certificate
active
06559557
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to circuitry for controlling automotive airbag or Supplemental Inflatable Restraint Systems, and more particularly, to circuitry for detecting non-deployment conditions in seemingly deployable circumstances and inhibiting deployment of the airbag based on detection of such conditions.
BACKGROUND OF THE INVENTION
Airbags are commonplace in automotive vehicles as a result of the need to improve occupant safety in collisions. In fact, airbags are standard equipment in many, if not most, late model automotive vehicles. These airbags are typically located in strategic places, such as the steering wheel of a vehicle, and are intended to help reduce occupant injury in the event of a crash. In general, airbag management requires specialized systems for detecting collisions, deploying airbags when appropriate, and also inhibiting airbag deployment when the crash is not sufficiently severe to warrant airbag deployment.
Airbag management systems typically include at least one acceleration sensor, commonly referred to as an accelerometer, to sense acceleration/deceleration along a specific axis. Deployment of the airbag generally occurs only when the accelerometer senses at least a minimum acceleration along an appropriate axis. Typically, an airbag management system includes a number of accelerometers for sensing acceleration along a corresponding number of axes.
In the operation of typical airbag management systems, an accelerometer senses acceleration and produces an acceleration signal, wherein the acceleration signal is processed via a decision circuit to determine whether airbag deployment is warranted. Generally, however, great care must be exercised in designing such systems to avoid inadvertent airbag deployment. Inadvertent airbag deployment is not only costly, as the result of having to repair and replace the deployed airbag, but it can also create a potentially dangerous situation for the occupants. For example, inadvertent deployment may force the driver out of position or otherwise impair the driver's ability to safely operate the vehicle. To reduce the possibility of inadvertent airbag deployment, some airbag management systems include a redundant “arming” sensor (e.g., accelerometer) operable to alert the system of a potential deployment condition only if the crash is above a crash severity threshold.
Referring to
FIG. 1
, one known airbag management system
100
is shown including such a redundant arming sensor
110
. System
100
also includes at least one accelerometer
120
suitably positioned for controlling a corresponding airbag. The accelerometer
120
senses and transduces an acceleration
130
into an analog acceleration signal proportional to the amount of acceleration sensed, typically measured in multiples of gravitation force units denoted by the symbol G.
The accelerometer
120
provides the analog acceleration signal to an analog to digital (A/D) converter
140
via signal path
122
which converts the signal to a digital acceleration signal and provides this digital signal to a microprocessor
150
via signal path
142
. The microprocessor
150
is electrically connected to a deployment circuit
160
via signal path
154
which is itself electrically connected to an inhibit deployment circuit
170
electrically connected to arming sensor
110
via signal path
112
. An output of the inhibit deployment circuit
170
is connected to an actuator (not shown) of an airbag
174
via signal path
172
.
The microprocessor
150
typically includes a deployment control algorithm
152
for determining whether the digital acceleration signal on signal path
142
is of sufficient magnitude to deploy airbag
174
, and provides a signal corresponding thereto to the deployment circuit
160
. The arming sensor
110
is also operable to sense acceleration and provide a corresponding acceleration signal to the inhibit deployment circuit
170
. Typically, the arming sensor
110
is configured to provide greater resolution in the lower G ranges, and the inhibit deployment circuit
170
is operable to process this signal to determine whether the crash event is sufficiently severe to allow deployment of the airbag
174
. If, for example, the inhibit deployment circuit
170
determines that the acceleration signal produced by arming sensor
110
is below a predefined G threshold, circuit
170
is operable to inhibit any deployment signal produced by deployment circuit
160
on signal path
162
so that the airbag
174
is not deployed. If, on the other hand, the inhibit deployment circuit
170
determines that the acceleration signal produced by arming sensor
110
is above the predefined G threshold, circuit
170
is operable to pass any deployment signal produced by deployment circuit
160
to airbag
174
via signal path
172
to thereby deploy the airbag
174
.
The airbag management system
100
just described includes a multitude of components including the arming sensor
110
. These components increase the cost and complexity of system
100
. Further, as the number of accelerometers
120
increase, the number of arming sensors
110
increases linearly. Therefore, for every accelerometer
120
located in the vehicle to sense along a certain axis, an arming sensor
110
must be located along the same axis, and preferably in close proximity to the accelerometer. Not only is this cost restrictive, physically locating these devices in close proximity is oftentimes impractical and sometimes impossible. Moreover, physical and electronic constraints of standard microprocessors limit the number of accelerometers that the system can manage. As more accelerometers are added, processing time becomes a constraint and thus unacceptable delays in the deployment of the airbag ensue, thereby compromising the safety of the occupants of the vehicle.
Referring now to
FIG. 2
, another known airbag management system
180
is shown that eliminates the need for arming sensor
110
but that incorporates and implements the arming sensor's functions into a microprocessor
190
. System
180
includes many of the same components as system
100
of
FIG. 1
, and like components are therefore identified with like reference numbers. For example, an accelerometer
120
is responsive to an acceleration
130
to produce an analog acceleration signal on signal path
122
. An A/D converter
140
is operable to convert the analog acceleration signal on signal path
122
to a digital acceleration signal and provide this digital acceleration signal on signal path
142
. Microprocessor
190
is responsive to the digital acceleration signal on signal path
142
to produce a deployment control signal on signal path
194
if a crash of sufficient severity is detected, in accordance with deployment control algorithm
152
as described hereinabove. A deployment circuit
170
is, in turn, responsive to the deployment control signal on signal path
194
to produce a corresponding drive signal on signal path
172
to thereby deploy air bag
174
.
In addition to algorithm
152
, the microprocessor
190
is also programmed to assume the function of the arming sensor
110
of
FIG. 1
by including a software algorithm
192
operable to determine the magnitude of the digital acceleration signal on signal path
142
and assess whether this magnitude is sufficiently large along the proper axis to cause the deployment control algorithm (e.g., algorithm
152
) to produce an active deployment control signal for deploying the air bag
174
.
Referring to
FIG. 3
, a flowchart illustrating one known embodiment of a software algorithm
200
, resident within microprocessor
190
of
FIG. 2
, is shown, wherein algorithm
200
is operable to process the digital acceleration signal and determining whether to deploy, or inhibit deployment of, the airbag
174
. The algorithm
200
thus incorporates therein both the deployment control algorithm
152
program and algorithm
192
described with respect to FIG.
2
. At step
202
, the digital acceleration signal is received, a
Boger Lee C.
Manlove Gregory J.
Delphi Technologies Inc.
Funke Jimmy L.
Rios Robert J.
Sircus Brian
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