Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Vehicle subsystem or accessory control
Reexamination Certificate
2002-06-20
2003-11-04
Chin, Gary (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Vehicle subsystem or accessory control
C280S735000, C180S273000
Reexamination Certificate
active
06643575
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention generally relates to a vehicle occupant protection system for securing the safety of a vehicle occupant or occupant of a vehicle seat and, more specifically, to a seat load measuring system for use in such a vehicle occupant protection system and for measuring the load weight a vehicle seat bears or the weight of the occupant of the vehicle seat.
2. Description of the Prior Art
Vehicles have become equipped with seat belt systems and air bag systems as vehicle occupant protection devices. In order to enhance the performance of such devices, attempts are being made to control the operation of each vehicle occupant protection device in response to the weight of the occupant of a vehicle seat equipped with the vehicle occupant protection device as well as a detection of the occurrence of a vehicle crash. For example, the quantity of air bag deploying gas, the deploying speed of air bags and/or the pretension of seat belts are controlled in response to the occupant's weight.
Generally, a seat load measuring system provided for a vehicle seat comprises four weight sensor assemblies and a hub assembly for collecting the weight sensor assembly outputs and providing an output signal determined by the weight of the occupant of the vehicle seat.
FIG. 1
is a diagram showing a conventional way of determining the seat load component W
LD
posed on each of the weight sensors from the output W of the weight sensor.
In
FIG. 1
, the horizontal axis indicates time and the vertical axis indicates the output W of the weight sensor. It is assumed in this figure that the used sensors are capable of measuring not only the pressure (i.e., the positive pressing force forward the sensor) but also the negative pressure or the tension. The least upper bound and the greatest lower bound of the weight sensor output are indicated by dotted lines Wmax and Wmin, respectively. A weight level W
0
indicates the output level of a weight sensor assembly measured without applying any load thereto. After installing a seat assembly which includes the seat load measuring system in a vehicle under manufacturing, the output W
0
+W
1
of each weight sensor assembly which includes a seat weight component W
1
applied to the weight sensor assembly is stored as a zero point in the weight measuring hub assembly. Thereafter, the seat load (i.e., the load applied to a seat) is obtained by summing up seat load components given by the four weight sensor assemblies used for the seat. The seat load component for each weight sensor assembly is calculated as W−(W
0
+W
1
) from the output W of the sensor assembly and the stored zero point W
0
+W
1
for the sensor assembly.
However, the zero point of one or more weight sensor assembly may deviate far from the stored value W
0
+W
1
to a value W
0
+W
2
due to any cause such as a vehicle crash or distortion of any rigid member of the seat which is caused by the lowering of durability. In such a case, if the seat load component is still determined by the expression W−(W
0
+W
1
)using the old correction value W
1
, this causes an error of W
2
−W
1
. Further, if the deviation W
2
is too large, which means that the positive dynamic range (PDR) is narrower than a necessary range, then the output of the weight sensor may be saturated for a large load. In this case, the seat assembly needs a disassembly and adjustment or the substitution of a new one.
Thus, if a motor vehicle has experienced any vehicle crash, it is necessary to make a test to see how much (W
2
−W
1
) the zero point of each weight sensor has deviate from the current position (W
1
) and whether the deviation quantity W
2
−W
1
is in a tolerable range or not. Doing this enables the user of the vehicle to take an appropriate measure in accordance with the test results.
In order to meet the needs, we disclosed “Seat Load Measuring System with Zero point-adjusting Capability” in Japanese patent application No. 2001-196790. In this system, the zero point is adjusted by a repairman using a command input device. (This Japanese application is not yet published, and is thus not prior art to the present application.)
Aoki disclosed “Diagnostic Method for Seat Load Measuring Device” in Japanese patent unexamined publication No. 2000-298057 (October, 2000). In this device, the first output from a weight sensor with no load thereon is measured; the second output from the weight sensor with a predetermined load thereon is measured; a test is made to see if the difference between the first and second output values is within a predetermined value; and if not, an alert signal indicative of abnormality is issued to the user.
However, in the above-mentioned systems, the zero point adjustment or the device diagnosis has to be made by a repairman using a test weight of a predetermined weight and/or command input device as shown in FIG.
1
. In other words, even if any seat load measuring device is abnormal, the abnormality can not be found until the user has the vehicle examined by a repairman, which can brought a worst case where the occupant protection system is activated under the abnormal state of the seat load measuring device. Further, seat load measurements are conducted on the basis of the zero points the values of which might have deviated from the values set in the last zero point adjustment until the zero points of the seat load measuring devices are adjusted by a repairman.
Therefore it is an object of the invention to provide a seat load measuring system that automatically makes a self-diagnosis and, if necessary, zero point adjustment without using a test weight in response to a vehicle crash.
SUMMARY OF THE INVENTION
According to an aspect of the invention, there is provided an occupant protection apparatus of a motor vehicle provided with a seat load measuring system capable of automated self-diagnosis and/or zero point adjustment at the time of crash. The occupant protection system includes a seat load measuring subsystem. The seat load measuring subsystem includes a plurality of weight sensors attached to a vehicle seat. Each of the weight sensors provides a weight signal responsive to a weight load applied to the weight sensor. The occupant protection system further includes at least one crash sensor for outputting the magnitude of a crash of the vehicle; a controller (
31
in FIG.
2
), responsive to the magnitude of the crash for providing a crash signal determined by the magnitude and, responsive to a decision that the crash signal has reached a predetermined level for providing control information on the basis of the weight signals from the weight sensors; and one or more occupant protection portions which each use an air bag, a seat belt or the like to provide a protection in response to the control information. The seat load measuring subsystem further includes a control portion (
21
in
FIG. 2
) responsive to a reception of the crash signal for automatically making a diagnosis on each weight sensor or a zero adjustment of each weight sensor.
According to another aspect of the invention, a seat load measuring system for use in an occupant protection system of a vehicle is provided. The occupant protection system includes a crash detecting portion responsive to a detection of a crash for providing a crash signal determined by the magnitude of the crash and a portion responsive to a decision that said crash signal has reached a predetermined level for executing a protection operation on the basis of control information provided by the seat load measuring system. The seat load measuring system includes: a plurality of weight sensors attached to a vehicle seat, each weight sensor providing a weight signal responsive to a weight load applied to each weight sensor, the weight signal being used either as the control information or for generating the control information; and a controller responsive to a reception of the crash signal for automatically making a diagnosis on each weight sensor or
Ishida Shoichi
Kuwahara Sadayuki
Chin Gary
Denso Corporation
Oliff & Berridg,e PLC
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