Electrical transmission or interconnection systems – Vehicle mounted systems – Automobile
Reexamination Certificate
1999-02-01
2001-04-17
Paladini, Albert W. (Department: 2836)
Electrical transmission or interconnection systems
Vehicle mounted systems
Automobile
C307S009100, C280S735000, C280S736000
Reexamination Certificate
active
06218738
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ignition control method in a passive safety device for a vehicle, and in particular to an ignition control method in a passive safety device having air bags and pretensioners.
2. Description of the Related Art
Conventionally, as disclosed in Japanese Patent No. 2559830, an air bag system having a back-up condenser is known. This air bag system is normally operated with power supplied from an onboard battery. When the battery power supply is shut off, the system is operated with power supplied from the back-up condenser.
If a plurality of air bags are provided on a vehicle, the back-up condenser may be required to supply power to the plurality of air bags after the battery power supply is shut off. Additionally, requests of operation for the plurality of air bags may be generated with certain time lags. Thus, in a vehicle provided with a plurality of air bags, the back-up condenser must have a relatively long back-up time.
When an air bag is inflated, a path may be formed which short-circuits the ignition circuit corresponding to the inflated air bag. If the air bag is continued to be supplied with power in such a situation, the power stored in the back-up condenser is wasted by the inflated air bag. In this case, a sufficiently long back-up time cannot be achieved.
In the above-mentioned conventional air bag system, when electric energy charged in the back-up condenser has decreased to a predetermined extent, it is determined that one of the air bags is supplied with an ignition signal, and a power supply line to that air bag is shut off. Therefore, it is possible to positively prevent the inflated air bag from being supplied with power, so that electric power of the back-up condenser is not wasted. Thus, according to the conventional air bag system, it is possible to achieve a sufficiently long back-up time in a vehicle provided with a plurality of air bags.
However, the back-up time expected in the conventional air bag system is as short as 100 to 200 milli seconds. That is, the conventional air bag system is designed so as to be used to control front and side air bags which must be operated immediately after a phenomenon such as a collision has occurred which phenomenon could cause the shutoff of the battery power supply. Thus, the conventional air bag system can sufficiently satisfy a desired performance with the above-mentioned very short back-up time.
When a roll over of a vehicle has occurred, a passenger's head can be effectively protected if, for example, an air bag is inflated near the passenger's head. A roll over of a vehicle may occur a few seconds after a phenomenon causing the shutoff of the battery power supply has occurred. Thus, when an air bag for protecting a passenger's head (hereinafter referred to as a head-protecting air bag) is provided on a vehicle, a considerably long back-up time is required as compared to a case in which only front and side air bags are provided.
In a large-scale air bag system having the front air bags, the side air bags, and the head-protecting air bags, power consumption of an ignition control device becomes large. In such an air bag system, it is not possible to achieve a sufficiently long back-up time by using the conventional technique, that is, by shutting off power supply to the inflated air bag.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an ignition control method in a passive safety device for a vehicle which can achieve a sufficiently long back-up time when power supply is shut off.
The above-mentioned object of the present invention can be achieved by an ignition control method in a passive safety device for a vehicle for operating an ignition control device of the passive safety device using electric power stored in a back-up condenser when power supply is shut off, comprising:
a mode-shifting step of shifting an operation mode of the ignition control device from a normal mode to a low-power-consumption mode.
In this invention, the operation mode of the ignition control device is shifted from the normal mode to the low-power-consumption mode. According to the low-power-consumption mode, power consumption of the ignition control device is reduced. Thus, according to the invention, a relatively long back-up time can be achieved by using electric power stored in the back-up condenser after power supply is shut off.
In this case, the passive safety device may comprise a high-response safety device which requires a relatively short time to determine a request of operation, and a low-response safety device which requires a relatively long time to determine a request of operation, and the mode-shifting step may comprise an expected-state detecting step of detecting a predetermined state in which a request of operation to the low-response safety device is expected to occur and a condition determining step of determining an establishment of a condition for shifting to the low-power-consumption mode when at least one of the conditions that a predetermined time has elapsed after the shutoff of power supply and that the predetermined state is detected is established.
In this invention, the passive safety device includes a high-response safety device and a low-response safety device. It is necessary to achieve a sufficiently long back-up time after power supply is shut off to positively operate the low-response safety device. In the invention, if the low-power-consumption mode is achieved at a time when the predetermined time has elapsed after the shutoff of the power supply, a sufficiently long back-up time can be achieved without affecting the operation of the high-response safety device. Additionally, in the invention, if the low-power-consumption mode is achieved when a request of the operation to the low-response safety device is expected to be generated, the low-response safety device can be positively operated. Thus, according to the invention, it is possible to positively achieve a sufficiently long back-up time required to positively operate the low-response safety device.
The passive safety device may comprise a front air bag and a side air bag which require a relatively short time to determine a request of operation and a head-protecting air bag which requires a relatively long time to determine a request of operation.
In this invention, the front air bag and the side air bag are inflated with a high response so as to protect a passenger when a front collision or a side collision of a vehicle occurs. On the other hand, the head-protecting air bag is inflated so as to protect the vicinity of the passenger's head when, for example, a roll over occurs. In the invention, since a sufficiently long back-up time is achieved, it is possible to positively inflate the head-protecting air bag.
In the low-power-consumption mode, at least one of the processes of shutting off power supply to a request-of-operation detecting part which detects a request of operation to the front and side air bags, shutting off an ignition signal to an ignition device for the front and side air bags, and lowering an operation clock frequency of the ignition control device may be performed.
In the invention, requests of operation for the front air bag and the side air bag are to be detected immediately after the power supply is shut off. Thus, it is not necessary to operate the request-of-operation detecting part after a certain time has elapsed after the power supply is shut off. If power to the request of operation detecting part is shut off in such a situation, the low-power-consumption mode can be achieved without causing any substantial problems.
Similarly, requests of operation to the front and side air bags are not generated after a certain time has elapsed after the power supply is shut off. If the ignition signal is shut off in such a situation, the low-power-consumption mode can be achieved without causing any substantial problems.
Additionally, in the invention, it is not necessary to monitor a genera
Paladini Albert W.
Pillsbury & Winthrop LLP
Toyota Jidosha & Kabushiki Kaisha
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