U.S. patent application number 09/739220 was filed with the patent office on 2001-07-05 for device for controlling expansion of an air bag apparatus.
Invention is credited to Sakakida, Masafumi.
Application Number | 20010006288 09/739220 |
Document ID | / |
Family ID | 18502120 |
Filed Date | 2001-07-05 |
United States Patent
Application |
20010006288 |
Kind Code |
A1 |
Sakakida, Masafumi |
July 5, 2001 |
Device for controlling expansion of an air bag apparatus
Abstract
A device for controlling an air bag apparatus includes a first
acceleration sensor mounted in a passenger compartment for
detecting an acceleration thereof and a second acceleration sensor
mounted in a front portion of a vehicle body. A control unit
electrically connected to the first and second acceleration sensors
does not output an operation signal to a trigger circuit for
inflaters until a first value derived from a signal detected by the
first acceleration sensor has exceeded a first criterion and when a
second value derived from a signal detected by the second
acceleration sensor has exceeded a predetermined acceleration
greater than an acceleration corresponding to the first criterion.
In the event of a collision, because a very large impact force is
applied to the front portion of the vehicle body, the control unit
actuates the air bag apparatus appropriately based on the signals
detected by both the first and second acceleration sensors. If a
shock is applied to the vehicle body due to the run-up of a wheel
onto a curb or the like, and even if the first acceleration sensor
outputs a signal that allows actuation of the air bag apparatus,
the second acceleration sensor does not output the operation
signal, because it is not outputted until a further greater shock
is applied to the vehicle body, thus preventing erroneous operation
of the air bag apparatus.
Inventors: |
Sakakida, Masafumi;
(Aki-gun, JP) |
Correspondence
Address: |
Donald R. Studebaker, Esq.
NIXON PEABODY LLP
Suite 800
8180 Greensboro Drive
McLean
VA
22102
US
|
Family ID: |
18502120 |
Appl. No.: |
09/739220 |
Filed: |
December 19, 2000 |
Current U.S.
Class: |
280/735 |
Current CPC
Class: |
B60R 2021/01006
20130101; B60R 21/0133 20141201; B60R 21/013 20130101 |
Class at
Publication: |
280/735 |
International
Class: |
B60R 021/32; B60R
021/16 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 28, 1999 |
JP |
P 11-373414 |
Claims
What is claimed is:
1. A device for controlling an air bag apparatus mounted in an
automotive vehicle having a passenger compartment defined therein,
said device comprising: a first acceleration sensor mounted in the
passenger compartment for detecting an acceleration thereof; a
second acceleration sensor mounted in a front portion of the
vehicle body; and a control unit electrically connected to said
first and second acceleration sensors so that signals from said
first and second acceleration sensors are inputted to said control
unit; wherein when a first value derived from a signal detected by
said first acceleration sensor has exceeded a first criterion and
when a second value derived from a signal detected by said second
acceleration sensor has exceeded a predetermined value greater than
the first criterion, said control unit outputs an operation signal
for operating the air bag apparatus.
2. The device according to claim 1, wherein said control unit
outputs the operation signal regardless of presence or absence of
the signal detected by said second acceleration sensor, when the
first value has exceeded a second criterion greater than the first
criterion.
3. The device according to claim 2, wherein the second criterion is
greater than the predetermined value.
4. A device for controlling an air bag apparatus mounted in an
automotive vehicle having a passenger compartment defined therein,
said device comprising: a first acceleration detector for always
detecting an acceleration of the passenger compartment; a control
unit for determining necessity of operating the air bag apparatus
by comparing a first value derived from a signal detected by said
first acceleration detector with a first criterion; and a second
acceleration detector mounted in a front portion of the vehicle
body for outputting an operation signal when a second value derived
from a signal detected by said second acceleration detector has
exceeded a predetermined value greater than the first criterion;
wherein when the first value has exceeded the first criterion and
when said second acceleration detector has outputted the operation
signal, said control unit outputs an operation signal for operating
the air bag apparatus.
5. The device according to claim 4, wherein said control unit
outputs the operation signal regardless of presence or absence of
the operation signal from said second acceleration detector, when
the first value has exceeded a second criterion greater than the
first criterion.
6. The device according to claim 5, wherein the second criterion is
greater than the predetermined value.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a device for controlling
expansion of an air bag apparatus.
[0003] 2. Description of the Related Art
[0004] Japanese Laid-open Patent Publication (unexamined) No.
10-315907 discloses a device for controlling expansion of an air
bag apparatus having a plurality of inflaters. This device includes
an acceleration sensor for detecting an acceleration of a passenger
compartment and a crash sensor located at a front portion of a
vehicle body and having a switching mechanism that closes an
electric circuit in the event of a collision above a predetermined
level. The device determines based on a signal from the
acceleration sensor whether or not the inflaters should be
operated, and also determines the operation modes of the inflaters
according to the degree of the collision within a predetermined
time after the electric circuit has been closed, making it possible
to optimize the operation of the inflaters.
[0005] As in the device of the above-described construction, the
general practice is such that whether the inflaters should be
operated is determined based on the signal from the acceleration
sensor. From the viewpoint of operating the air bag apparatus at an
early stage, it is preferred that a criterion for determining the
necessity of operating the air bag apparatus be set to the lowest
possible value (acceleration).
[0006] However, such setting cannot deal with a recent tendency of
wheels toward increase in size. More specifically, as shown in FIG.
4, if a wheel 101 (phantom line depicts a conventional wheel) runs
up onto a curb 102 or the like, there is a possibility that the
acceleration sensor detects an acceleration signal for expanding
the inflaters notwithstanding that no collision has occurred,
resulting in erroneous operation of the air bag apparatus.
SUMMARY OF THE INVENTION
[0007] The present invention has been developed to overcome the
above-described disadvantages.
[0008] It is accordingly an objective of the present invention to
provide a device for controlling expansion of an air bag apparatus,
which is capable of positively preventing erroneous operation of
the air bag apparatus that may occur when an automotive vehicle
runs up onto a curb or the like.
[0009] In accomplishing the above and other objectives, the device
according to the present invention includes a first acceleration
sensor mounted in a passenger compartment for detecting an
acceleration thereof, a second acceleration sensor mounted in a
front portion of a vehicle body, and a control unit electrically
connected to the first and second acceleration sensors so that
signals from the first and second acceleration sensors are inputted
to the control unit. When a first value derived from a signal
detected by the first acceleration sensor has exceeded a first
criterion and when a second value derived from a signal detected by
the second acceleration sensor has exceeded a predetermined value
greater than the first criterion, the control unit outputs an
operation signal for operating the air bag apparatus.
[0010] By this construction, in the event of a collision, because a
very large impact force is applied to the front portion of the
vehicle body, not only the first value exceeds the first criterion,
but the second value also exceeds the predetermined value. As a
result, the control unit actuates the air bag apparatus
appropriately. On the other hand, If a shock is applied to the
vehicle body due to a run-up of a wheel onto a curb or the like,
and even if the first acceleration sensor outputs a signal that
allows actuation of the air bag apparatus, the second acceleration
sensor does not output the operation signal. The reason for this is
that the operation signal from the second acceleration sensor is
set so as not be outputted until a further greater shock is applied
to the vehicle body, thus preventing erroneous operation of the air
bag apparatus.
[0011] Advantageously, the control unit outputs the operation
signal regardless of the presence or absence of the signal detected
by the second acceleration sensor, when the first value has
exceeded a second criterion greater than the first criterion.
[0012] This construction ensures appropriate actuation of the air
bag apparatus under the condition in which the air bag apparatus
should normally be actuated unless the second acceleration sensor
is out of order (in the event of failure) or in which the air bag
apparatus cannot be actuated by reason that the second acceleration
sensor cannot detect the predetermined acceleration, although it is
in good order (in the event of, for example, a rear end collision
or a collision in which the vehicle rushes under a large
vehicle).
[0013] The second criterion is so set as to be greater than the
predetermined value. By so setting, the device according to the
present invention can distinguish a shock caused by the run-up onto
a curb or the like from a shock caused by a vehicle collision,
making it possible to prevent erroneous operation of the air bag
apparatus and guarantee appropriate actuation of the air bag
apparatus.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The above and other objectives and features of the present
invention will become more apparent from the following description
of a preferred embodiment thereof with reference to the
accompanying drawings, throughout which like parts are designated
by like reference numerals, and wherein:
[0015] FIG. 1 is a block diagram of a device according to the
present invention;
[0016] FIG. 2 is a diagram explanatory of the setting of first and
second acceleration sensors installed in the device of FIG. 1;
[0017] FIG. 3 is a flowchart explanatory of how to control
expansion of air bags in the device of FIG. 1; and
[0018] FIG. 4 is a schematic view when a wheel runs up onto a
curb.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0019] This application is based on an application No. 11-373414
filed Dec. 28, 1999 in Japan, the content of which is herein
expressly incorporated by reference in its entirety.
[0020] Referring now to the drawings, there is schematically shown
in FIG. 1 an automotive vehicle 1 having a first acceleration
sensor or detector 3 mounted in a passenger compartment 2 defined
therein and a second acceleration sensor or detector 5 mounted in a
front portion 4 of a vehicle body and located forwardly of the
first acceleration sensor 3.
[0021] In this embodiment, the first acceleration sensor 3 is
installed on a cowl upper panel 6 substantially at the center
thereof in the widthwise direction of the vehicle body, and is
covered with an instrument panel 7. The first acceleration sensor 3
is a sensor for outputting an acceleration signal while always
detecting the acceleration.
[0022] On the other hand, the second acceleration sensor 5 is
installed on a rear face of a bumper reinforcement 8 substantially
at the center thereof in the widthwise direction of the vehicle
body. The second acceleration sensor 5 outputs an operation signal
by detecting an acceleration over a predetermined acceleration
value (criterion) in the event of a collision. By way of example,
the second acceleration sensor 5 includes a magnet, a mass always
attracted by the magnet, and a pair of contacts disposed close to
the mass, wherein in the event of collision, the mass moves towards
the contacts against the attraction of the magnet to turn the
contacts on.
[0023] As shown in FIG. 1, the signals from the first and second
acceleration sensors 3, 5 are inputted to a control unit U
electrically connected thereto, which outputs an operation signal
to a trigger circuit 10 for operating inflaters (air bags) 9 based
on such signals. The control by the control unit U is as
follows.
[0024] In principle, the control unit U integrates a signal
detected by the first acceleration sensor 3 and then determines
whether or not the integrated value exceeds a first threshold value
(basic criterion). The control unit U also determines the presence
or absence of an operation signal from the second acceleration
sensor 5. As shown in FIG. 2, the control unit U does not output
the operation signal to the trigger circuit 10 for the inflaters 9,
until the integrated value of the signal detected by the first
acceleration sensor 3 exceeds the first threshold value, and the
control unit U determines that the operation signal has been
outputted from the second acceleration sensor 5. The criterion or
the predetermined acceleration value of the second acceleration
sensor 5 is set to be greater than the acceleration (converted
value) corresponding to the first threshold value.
[0025] By so setting, in the event of an ordinary collision, the
air bags are caused to expand appropriately, while if a wheel runs
up onto a curb or the like, and even if the expansion of the air
bags is allowed based on the signal from the first acceleration
sensor 3, the second acceleration sensor 5 does not output the
operation signal and, hence, erroneous operation of the air bags is
prevented.
[0026] When the control unit U determines that the value
(integrated value) derived from the signal detected by the first
acceleration sensor 3 has exceeded a second threshold value (a
second criterion) greater than the first threshold value, the
control unit U outputs the operation signal to the trigger circuit
10 for the inflaters 9 regardless of the value detected by the
second acceleration sensor 5, as shown in FIG. 2. This is to expand
the air bags in the event of failure or damage of the second
acceleration sensor 5 or in the event of a rear end collision of
the vehicle body.
[0027] The acceleration (converted value) corresponding to the
second threshold value is set to be greater than the predetermined
acceleration (criterion) used for comparison with the value
detected by the second acceleration sensor 5. This is for the
purpose of expanding the air bags appropriately under the condition
in which the air bags should normally be expanded unless the second
acceleration sensor 5 is out of order (in the event of failure) or
in which the air bags cannot be expanded by reason that the second
acceleration sensor 5 cannot detect the necessity of expanding the
air bags, although it works well (in the event of, for example, a
rear end collision).
[0028] FIG. 3 depicts a flowchart showing a good representative of
the control by the control unit U.
[0029] According to this flowchart, at step S1, the signals from
the first and second acceleration sensors 3, 5 are inputted to the
control unit U, which in turn uses them to determine whether the
air bags should be expanded or not.
[0030] At step S2, the signal detected by the first acceleration
sensor 3 undergoes integration processing, and at step S3, a
determination is made whether or not an integrated value VB
obtained at step S2 is greater than the first threshold value V1.
This is to determine if a vehicle collision has occurred, based on
the signal from the first acceleration sensor 3.
[0031] If the determination at step S3 is YES, a determination is
made at step S4 whether or not the integrated value VB has exceeded
the second threshold value V2. This is to determine, in the event
of failure of the second acceleration sensor 5 or occurrence of a
rear end collision, the necessity of expanding the air bags
regardless of the presence or absence of the operation signal from
the second acceleration sensor 5.
[0032] The acceleration corresponding to the second threshold value
V2 is set to be greater than the criterion or predetermined
acceleration used for comparison with the signal from the second
acceleration sensor 5. This guarantees the operation of the air
bags even if the second acceleration sensor 5 is out of order or a
rear end collision occurs.
[0033] If the determination at step S4 is NO, a determination is
made at step S5 whether or not the operation signal is outputted
from the second acceleration sensor 5. This is to determine whether
a shock is caused by a collision or by a run-up of a wheel onto a
curb or the like.
[0034] The criterion i.e., the predetermined reference acceleration
for the second acceleration sensor 5 is set to be greater than the
acceleration corresponding to the first threshold value. In the
event of a collision, because a very large impact force is applied
to the front portion 4 of the vehicle body, even if the criterion
for the output signal from the second acceleration sensor 5 is set
greater than the acceleration corresponding to the first threshold
value, the second acceleration sensor 5 does not fail to output the
operation signal. On the other hand, if a shock is applied to the
vehicle body due to the run-up of a wheel onto a curb or the like,
and even if the first acceleration sensor 3 outputs a signal (the
integrated value thereof exceeds the first threshold value) that
allows expansion of the air bags, the second acceleration sensor 5
does not output the operation signal in response to the shock of
such a degree.
[0035] If the determination at step S5 is YES, which means that
both the first and second acceleration sensors 3, 5 have detected a
vehicle collision, the control unit U outputs an operation signal
to the trigger circuit 10, which in turn actuates the inflaters
9.
[0036] In contrast, if the determination at step S5 is NO, which
means that a shock detected by the first acceleration sensor 3 is
caused not by a vehicle collision but by the run-up onto a curb or
the like, the operation signal from the control unit U is not
outputted to the trigger circuit 10 for the inflaters 9, and the
procedure returns to step S1.
[0037] If the determination at step S4 is YES, which means that the
air bags should be expanded regardless of the presence or absence
of the operation signal from the second acceleration sensor 5, the
procedure advances to step S6 at which the operation signal is
inputted to the trigger circuit 10 for the inflaters 9. This
guarantees the appropriate operation of the air bags even if the
second acceleration sensor 5 is out of order or a rear end
collision occurs.
[0038] If the determination at step S3 is NO meaning no collision,
the operation signal is not outputted to the trigger circuit 10 for
the inflaters 9, and the procedure returns to step S1.
[0039] It is to be noted that although in this embodiment the first
and second criteria or threshold values and the predetermined
acceleration value for the second acceleration sensor 5 are common
in terms of the reference values for determining the degree of
collision, their units differ from each other and, hence, the
magnitudes thereof have been determined by converting the first and
second threshold values to respective acceleration values. However,
if all of the reference values are so determined as to have the
same unit, no conversion is necessary prior to comparison.
[0040] It is also to be noted that although in the above-described
embodiment the second acceleration sensor 5 has been described as
outputting an operation signal when the value detected thereby
exceeds a predetermined acceleration value, it may be so designed
that the second acceleration sensor 5 always outputs the operation
signal to the control unit U, which in turn determines whether or
not the value detected by the second acceleration sensor 5 has
exceeded the predetermined acceleration value.
[0041] It is further to be noted that although in the
above-described embodiment an integrated value of a signal
(acceleration) detected by the first acceleration sensor is used as
a factor for determining expansion of the air bags upon comparison
thereof with the first or second threshold value, the expansion of
the air bags may be determined by comparing the acceleration with
the first or second threshold value. In that case, it is natural
that the first and second threshold values are determined in terms
of acceleration.
[0042] Although the present invention has been fully described by
way of examples with reference to the accompanying drawings, it is
to be noted here that various changes and modifications will be
apparent to those skilled in the art. Therefore, unless such
changes and modifications otherwise depart from the spirit and
scope of the present invention, they should be construed as being
included therein.
* * * * *