Land vehicles – Wheeled – Attachment
Reexamination Certificate
1999-10-20
2001-07-24
Rice, Kenneth R. (Department: 2167)
Land vehicles
Wheeled
Attachment
C180S268000
Reexamination Certificate
active
06264236
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an occupant restraint system such as an airbag device, to secure safety for an occupant in the event of a vehicle collision. More particularly, the present invention relates to an occupant restraint system wherein the operational mode is variable according to the size of a person sitting on a seat.
2. Description of the Related Art
Vehicles are equipped with occupant restraint systems such as airbag devices for protecting occupants in the event of vehicle collision and, in the United States, it has been considered to require vehicles to be provided with such restraint systems by regulation. As an example, an airbag device includes an inflator and an airbag wherein the inflator actuates to inflate the airbag and the inflated airbag restrains an occupant, thereby preventing the occupant from colliding with a vehicle body or preventing the occupant from being thrown out of the vehicle. The occupant restraint system is directed to secure the safety for an occupant by restraining the body of the occupant in the event of a vehicle collision.
In case where the occupant is an infant or a child, however, the airbag may injure the infant or the child if the airbag is deployed in a normal mode. Therefore, it is required to detect the constitution of the occupant, and to deploy the airbag in a mode different (including a case of not deploying the airbag) from the normal mode when it is detected that the occupant is an infant or a child. However, means for achieving the aforementioned operation have never been realized.
SUMMARY OF THE INVENTION
The present invention is made under the above circumstances and the object of the present invention is to provide an occupant restraint system wherein when the occupant is an infant or a child, the operational mode of an airbag can be changed to a mode suitable for the infant or the child.
A first aspect of the present invention for solving the problems is an occupant restraint system for restraining an occupant in the event of a vehicle collision, comprising an occupant sensor for detecting the constitution of the occupant sitting on a seat, and a tension switch installed on a seat belt which becomes in a first state when a tension exceeding a certain value (first threshold) is exerted on the seat belt and becomes in a second state in cases of other situations, wherein the operational mode of the occupant restraint system is variable according to the conditions of the occupant sensor and the tension switch.
In this aspect, according to the conditions of the occupant sensor for detecting the constitution of the occupant sitting on a seat and a tension switch installed on the seat belt, it is determined whether the person sitting on the seat is an adult or a child. Even when a child seat is fixed to the seat, it can be securely detected that the occupant is a child whereby the operation mode can be changed.
A second aspect of the present invention for solving the problem is the first aspect characterized in that the operational mode is set to a mode different from the normal mode when the tension switch is in the first state, and the operational mode is set to a mode different from the normal mode according to the output of the occupant sensor when the tension switch is in the second state.
In this aspect, when the load on the tension switch exceeds the first threshold, it is determined that a child seat is on the seat and is fixed by the seat belt, that is, the occupant is a child, so the operational mode is set to a mode different from the normal mode. When the load on the tension switch does not exceed the first threshold, it is determined that a person is sitting on the seat. Then, it is determined whether the person is an adult or a child by using the output from the occupant sensor. When the person is a child, the operation mode is set to a mode different from the normal mode. Therefore, even when the child seat is fixed to the seat, it can be securely detected that the occupant is a child and the operational mode can be selected to correspond to the situation.
It should be noted that the term “normal mode” means an operational mode when, for example, the occupant is an adult and that the term “mode different from the normal mode” means, for example, an operational mode in which an airbag is deployed with a reduced force of deployment or is deployed in two stages or is not deployed. This is true for the aspects according to the respective claims.
A third aspect for solving the problem is the first aspect or the second aspect characterized in that the first threshold is in a range from 3 kgf to 15 kgf.
When the occupant normally wears the seat belt, there is no possibility that the average tension of the seat belt steadily exceeds 3 kgf in view of the performance of the retractor and also in view of the sufferance of the occupant. Accordingly, the lower limit of the first threshold is 3 kgf. The tension of the seat belt for fixing the child seat is normally about 10 kgf and the tension exceeding 15 kgf brings about significant error of the measurement of the seat weight. Accordingly, the upper limit of the first threshold is 15 kgf.
A fourth aspect for solving the problem is any one of the first through third aspects characterized in that the occupant sensor is a weight sensor which detects the load applied on the seat.
The weight sensor is employed as the occupant sensor, thereby securely detecting whether the occupant is an adult or a child.
A fifth aspect for solving the problem is the fourth aspect characterized in that the operational mode is set to a mode different from the normal mode when the tension switch is in the first state, and the operational mode is set to a mode different from the normal mode when the tension switch is in the second state and the load detected by the weight sensor is not exceeding another certain value (second threshold).
As described with regard to the second aspect, when the load on the tension switch exceeds the first threshold, it is determined that a child seat is on the seat and is fixed by the seat belt so that the occupant is a child and the operational mode is set to a mode different from the normal mode. When the load on the tension switch does not exceed the first threshold, it is determined that a person is sitting on the seat and, in addition, when the load on the weight sensor exceeds the certain value (second threshold), it is determined that the person is an adult on the seat, and the operational mode is set to the normal mode. When the load detected by the weight sensor does not exceed the certain value (second threshold), it is determined that a child is sitting on the seat and the operational mode is set to a mode different from the normal mode. Therefore, even when a bolster seat is mounted on the seat, it can be securely detected that the occupant is a child whereby the operation mode can be selected to correspond to the situation.
A sixth aspect for solving the problem is the fifth aspect characterized in that the second threshold W is determined by an equation W=&agr;X+Y wherein a load conversion factor is assumed as &agr;, the first threshold is assumed as X, a load to be exerted on the seat at which the operational mode of the occupant restraint system must be changed when the seat belt is not used is assumed as Y.
The load Y to be exerted on the seat at which the operational mode of the occupant restraint system must be changed means a load allowing judgement whether the occupant is a child or an adult and is primarily the same as the second threshold as stated with reference to the fifth aspect. However, when the occupant wears the seat belt, the tension of the seat belt affects the value detected by the weight sensors. That is, the tension when the occupant wears the seat belt does not exceed X as mentioned above. A value obtained by multiplying the value of the tension by the effect factor &agr; is added to the load to be detected by the weight sensors. Accordingly, the second threshol
Foley & Lardner
Rice Kenneth R.
Takata Corporation
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