Land vehicles – Wheeled – Attachment
Reexamination Certificate
2000-10-04
2002-05-07
Culbreth, Eric (Department: 3611)
Land vehicles
Wheeled
Attachment
C701S045000
Reexamination Certificate
active
06382667
ABSTRACT:
FIELD OF INVENTION
The present invention relates to a passenger restraining protective device and, more specifically, to a passenger restraining protective device that determines the state of the younger passenger sitting on a child seat fixed on the seat or on a booster seat and regulates the actuation of the air bag according to the circumstances.
DESCRIPTION OF THE RELATED ART
In vehicles provided with an air bag as a passenger restraining protective device for the front passenger seat, the air bag is inflated and deployed upon collision to protect an adult passenger sitting on the front passenger seat from the secondary collision in the car. On the other hand, in case where a baby or infant seat, a child or toddler seat, or a booster seat is mounted on the front passenger seat and an infant or the like is using the front passenger seat, there may be a case where complete deployment of the air bag is not desirable for safety reasons. Therefore, realization of the system that determines the case where an infant or a child with the stature smaller than that for an average six year old child (for example) is sitting on the front passenger seat and, accordingly, decreases a force to deploy the air bag or prohibits the deployment itself is required.
Conventionally, there is a circuit that determines whether or not a passenger is sitting on the seat to serve as an alarm for reminding the passenger to fasten the seat belt. In this determination circuit, a seat sensor determines the weight applied on the seat and turns an alarm lamp on the instrument panel ON when the seat belt is not fastened yet.
The seat sensor is a known weight sensor mounted at the bearing position on the floor of the car body where the leg section of the seat is fixed. By performing a calibration of an empty weight in advance, the weight of the passenger seated on the seat or the baggage placed on the seat may be detected as a value of the load (hereinafter the load is referred to as a seat weight). On the other hand, whether or not the seat belt is appropriately fastened may be checked by the ON-state of the known buckle switch.
For example, the following circumstances may be considered as typical cases where the air bag should not be deployed.
FIG. 8
is an explanatory drawing illustrating the state of the passenger in each case in a schematic manner connect. Case 1 shows a baby seat
51
is fixed on the seat
50
facing toward the rear with a seat belt
52
, and a baby is lying thereon. Case 2 shows where a child seat
55
is fixed on the seat
50
with the seat belt
52
and an infant (approximately up to 4 years old)
56
is sitting thereon. Case 3 shows a booster seat
58
is placed on the seat
50
and an infant (approximately up to 6 years old)
57
is sitting thereon with the seat belt
52
fastened. It is desirable to deploy the air bag
60
when an elementary school age child of a fourth grade or higher/or a small-statured adult (approximately 48 kg in weight)
59
is sitting on the seat with the seat belt
52
fastened (Case 4). Therefore, in order to discriminate Cases 1 to 3 and Case 4, the seat weight obtained by the seat sensor
70
(See
FIG. 6
) is used a basic variable. The average values of the seat weight are shown in the upper column of the Table 1 (when the seat belt is not yet fastened).
TABLE 1
Seat Weight List (When the Belt is Fastened) (kg)
1. Baby
2. Child
3. Booster
4. Small-Statured
Seat
Seat
Seat
Adult
Seat weight
15
23
25
48
(belt not fastened)
Seat weight
22
30
27
48-50
(belt fastened)
As shown in Case 2, the child seat is fastened on the seat with a seat belt, and one end of the lap belt of the seat belt is anchored to the floor of the car body. In the seat having such a structure, a belt tension generated when the seat belt is securely fastened presses the child seat from above against the surface of the car seat. Therefore, a downward force toward the car seat increases the seat weight correspondingly. In general, the belt tension is about 10 kgf for a child seat, and 2 kgf for a booster seat, which is almost the same as the case when the seat belt is fastened. The expected seat weights, which are to be increased by the belt tension, are approximately 7 kg and 2 kg respectively. The total weights applied to the car seat are shown in the lower columns (when the seat belt is fastened) of Table 1.
Therefore, as a normal determination, the circumstances of the front passenger seat when the deployment of the air bag should be controlled may be grasped by setting the threshold value of the seat weight to the value between 30 kg and 35 kg. In this case, a known tension switch for detecting the belt tension is used in addition to the seat sensor. The control circuit of the tension switch can maintain the upper and lower threshold values T by setting the same and setting the state of operation as appropriate.
It has been shown that the belt tension of the seat belt used when fixing the child seat onto the car seat differs depending on the configuration of the child seat or the seat body, or on the state of attachment. When the child seat is secured with the seat belt tightly fastened, the belt tension may exceed 10 kg. In this case, the seat weight with an infant sitting thereon may exceed 30 kg. The detected tension may vary by the vibration during driving operation. Therefore, in the method of determination of the state of the passenger as described above, the state of the front passenger seat cannot be determined accurately.
In addition, it may cause a phenomenon similar to the chattering by the vibration associated with the driving operation of the vehicle.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to solve the problems of the related art as described above, and to provide a passenger restraining protective device in which a tension switch is used for determining the state of the passenger sitting on the front passenger seat, and an accurate determination can be made based on seat weight information and information obtained from the tension switch to control whether or not the air bag is to be ignited.
In order to achieve the object described above, the present invention comprises a seat sensor for detecting the load value acting upon the seat, and a tension switch for detecting tension acting on the seat belt and being turned ON when the tension exceeds the threshold value, wherein a control signal for regulating the air bag deployment is supplied when the passenger state is such that the tension exceeds the threshold value and the tension switch is in the ON-state, or that the seat weight obtained from the seat sensor with the switch in the OFF-state is not more than the prescribed weight. Accordingly, the state in which the child seat or the like is fixed on the seat by the seat belt is detected so that the air bag deploying action upon collision is adequately controlled.
In this case, preferably, the tension switch is turned ON when the tension of the seat belt is between 3 kgf and 20 kgf. Accordingly, the air bag deployment is reliably realized when the seat belt is normally used by an adult passenger or the like.
Preferably, the first determined value is obtained by the equation W=&agr;X+Y, where,
W: first evaluation value
&agr;: a conversion factor of the seat load
X: tension load of the tension switch (<threshold value)
Y: threshold value of the seat weight,
and the first evaluation value is varied with tension. Accordingly, the errors in weight measurement by the seat sensor or the like caused by tension of the seat belt can be compensated and the accuracy of determination of the state of the passenger by weight measurement can be improved.
Preferably, when the tension switch is in the ON-state and the seat weight is not less than 50 kg, which is set as a second determination value, the regulating control signal is corrected and supplied to execute the deployment of the air bag. Accordingly, malfunction such as a cutoff of air bag for an adult passenger due to failure of the tension switch may be prevented.
Preferab
Culbreth Eric
Dunn David R.
Takata Corporation
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