JP4306475B2 - Vehicle occupant protection system - Google Patents

Description

  The present invention relates to a vehicle occupant protection system, and more particularly to a vehicle occupant protection system capable of preventing malfunction due to noise in failure diagnosis of an airbag sensor.

Conventionally, failure diagnosis such as a primary check of an airbag sensor in a vehicle occupant protection system is disclosed in Patent Document 1, for example. That is, a pulse signal (diagnostic signal, failure diagnosis signal) having a predetermined cycle is input to the airbag sensor, and failure diagnosis is performed based on an output signal output from the airbag sensor.
JP 2001-91536 A

  However, for example, if noise is applied to the input terminal of the failure diagnosis signal, the airbag sensor may malfunction. That is, there has been a case where failure diagnosis of the airbag sensor cannot be performed accurately.

  The present invention has been made in view of such circumstances, and even if noise occurs at the input terminal of a failure diagnosis signal, the airbag sensor can be prevented from malfunctioning by preventing the malfunction of the airbag sensor. It is an object of the present invention to provide a vehicle occupant protection system capable of accurately diagnosing vehicle sensors.

  Therefore, the present inventor has intensively studied to solve this problem, and as a result of repeated trial and error, has come up with the idea of using a condition signal for starting failure diagnosis, and has completed the present invention.

That is, the vehicle occupant protection system of the present invention includes an airbag sensor, and a reference signal generating means for generating a reference signal that is a signal for diagnosing a failure of the airbag sensor and having a predetermined period ; An occupant protection system for a vehicle, comprising: output signal generation means for generating an output signal of the airbag sensor based on the reference signal; and failure diagnosis means for performing failure diagnosis of the airbag sensor based on the output signal. And generating a condition signal as a condition for starting generation of the output signal based on a first signal that is a signal different from the reference signal and having a period different from the predetermined period of the reference signal . Condition signal generating means, and the output signal generating means generates the output signal based on the reference signal when the condition signal satisfies a predetermined condition. Characterized by (claim 1).

Further, the first signal is a signal having a cycle shorter than the predetermined cycle of the reference signal (claim 2).

The condition signal generating means includes a count signal generating means for generating the first signal that is a periodic signal that can be counted during a predetermined time, and the first signal generated during the predetermined time . And a count means for outputting the condition signal that is the counted number, and the output signal generating means stores the count number counted by the counting means in advance. When the predetermined reference count number is reached, the output signal is generated based on the reference signal (claim 3).

Further, the counting means counts the count number of the first signal generated while the reference signal is generated (claim 4).

  According to the vehicle occupant protection system of the present invention, when the condition signal satisfies the predetermined condition, the output signal is generated in the airbag sensor, so that the noise is on the input terminal of the reference signal. Even if it exists, malfunction of the sensor for airbags can be prevented. Specifically, even when noise is applied to the input terminal of the reference signal, the airbag sensor does not start generating an output signal if the condition signal does not satisfy a predetermined condition. That is, since the airbag sensor does not malfunction due to noise, failure diagnosis of the airbag sensor can be performed accurately.

  In addition, by making the condition signal and the reference signal into signals with different periods, the airbag sensor malfunctions even when the same noise is on the reference signal input terminal and the condition signal input terminal. Can be prevented. In other words, even when the same noise is applied to the input terminal for the reference signal and the input terminal for the condition signal, the failure diagnosis of the airbag sensor can be performed accurately.

  Further, the condition signal generating means includes the count signal generating means and the counting means, so that the condition can be easily set. That is, it is possible to determine whether or not the condition is satisfied only by counting the count number of the count signal and comparing the count number with a predetermined count number. Further, as the count signal generating means, for example, an airbag ECU used for performing ID code recognition processing of the airbag sensor can be used. That is, since an existing apparatus can be used, the present invention can be implemented without providing a new apparatus. Thereby, the present invention can be easily applied.

Further, the counting means counts the number of counts of the first signal generated while the reference signal is generated, so that the malfunction of the airbag sensor can be prevented more reliably. For example, when no noise is generated, the reference signal and the count signal are generated, and then the count number of the count signal is counted while the reference signal is generated. When the count number reaches the predetermined count number, the airbag sensor generates an output signal based on the continuously generated reference signal. On the other hand, if the same noise as the count signal is applied to the input terminals of the reference signal and the count signal, the reference signal and the count signal are generated and the count number of the count signal is to be counted. However, since the reference signal is not continuously generated, counting of the count number of the count signal ends. That is, the count ends without the count number of the count signal reaching the predetermined count number. Therefore, the airbag sensor does not generate an output signal. As a result, the airbag sensor does not malfunction. Also, if the same noise as the reference signal gets on the input terminals of the reference signal and the count signal, the reference signal and the count signal are generated, and the count number of the count signal is to be counted. However, while the reference signal is continuously generated, the count signal is generated continuously as well, and the count number of the count signal does not increase. That is, the count number of the count signal does not reach the predetermined count number. Therefore, the airbag sensor does not generate an output signal. As a result, the airbag sensor does not malfunction.

  Next, the present invention will be described in more detail with reference to embodiments and with reference to FIGS. FIG. 1 is a schematic block diagram of a vehicle occupant protection system according to the present embodiment. FIG. 2 is a time chart of each signal.

  As shown in FIG. 1, the vehicle occupant protection system mainly includes an airbag ECU 1 and an acceleration sensor unit 2. The airbag ECU 1 performs ignition control of the airbag module based on the output signal of the acceleration sensor 21 and performs failure diagnosis of the acceleration sensor 21. The airbag ECU 1 is disposed substantially at the center of the vehicle. Here, in this embodiment, only failure diagnosis of the acceleration sensor 21 will be described, and description of ignition control of the airbag module will be omitted. Furthermore, in the present embodiment, an initial diagnosis, that is, a failure diagnosis in the primary check among the failure diagnosis of the acceleration sensor 21 will be described.

  The airbag ECU 1 includes a reference signal generation unit (reference signal generation unit) 11, a count signal generation unit (condition signal generation unit, count signal generation unit) 12, and a failure diagnosis unit (failure diagnosis unit) 13. The The reference signal generator 11 generates a reference signal, that is, a signal used for failure diagnosis of the acceleration sensor 21. As shown in the second stage of FIG. 2, this reference signal is a pulse signal generated by a primary check start signal and generated until the primary check ends. The primary check is started when the ignition switch is turned on, and is ended when a predetermined time has elapsed. The time for this primary check is, for example, 100 msec to 200 msec. That is, the period of the reference signal is 100 msec to 200 msec.

  The count signal generator 12 generates a count signal for generating a count number N (condition signal) described later. This count signal is a short-cycle pulse signal generated after the start of the primary check, as shown in the uppermost stage of FIG. Specifically, the count signal is a pulse signal having a cycle shorter than the cycle of the reference signal described above. The cycle of this count signal is, for example, 10 μsec.

  The failure diagnosis unit 13 performs failure diagnosis of the acceleration sensor 21 based on an output signal of the acceleration sensor 21 described later. That is, the failure diagnosis unit 13 compares the output signal output from the acceleration sensor 21 with the output signal in the normal state to diagnose whether the acceleration sensor 21 is in a normal state or an abnormal state. If it is in an abnormal state, the acceleration sensor 21 determines that there is a failure and turns on a warning light.

  The acceleration sensor unit 2 includes an acceleration sensor 21 and a sensor control unit 22. The acceleration sensor unit 2 is disposed, for example, on the front and left / right sides of the vehicle and is connected to the airbag ECU 1. The acceleration sensor 21 is a sensor that can detect the generated acceleration. For example, the acceleration sensor 21 disposed in front of the vehicle can detect acceleration generated in front of the vehicle when the vehicle collides.

  The sensor control unit 22 includes a reference signal input unit 221, a count signal input unit 222, a counter (counting unit) 223, an output signal generation unit (output signal generation unit) 224, and an output signal output unit 225. The The reference signal input unit 221 is connected to the reference signal generation unit 11 of the airbag ECU 1 described above, and inputs the reference signal generated by the reference signal generation unit 11. The count signal input unit 222 is connected to the count signal generation unit 12 of the airbag ECU 1 described above, and inputs the count signal generated by the count signal generation unit 12. The reference signal input unit 221 and the count signal input unit 222 are input terminals provided in the acceleration sensor unit 2.

  The counter 223 counts the number of occurrences (count number) N of the count signal input to the count signal input unit 222 as shown in the uppermost stage of FIG. However, the counter 223 counts only while the reference signal is input to the reference signal input unit 221. That is, when the reference signal is input again after the reference signal is completed, counting of the count number N of the count signal is started from the beginning. Therefore, the count number N of the count signal increases while the reference signal generator 11 generates the reference signal. The count number N has a role as a condition signal that is a condition for starting output signal generation by the output signal generator 224.

  The output signal generator 224 determines whether or not the count number N counted by the counter 223 has reached a pre-stored reference count number Nt. That is, it is determined whether or not the counter number N satisfies a preset condition. Here, the reference count number Nt is 4. As shown in the uppermost stage of FIG. 2, while the reference signal generator 11 generates the reference signal, the count number N of the count signal increases, so the count number N becomes the reference count number Nt. Reach.

  Further, when it is determined that the count number N has reached the reference count number Nt, the output signal generation unit 224 is input to the reference signal input unit 221 from the time when the count number N reaches the reference count number Nt. The reference signal is input to the acceleration sensor 21. That is, a virtual failure diagnosis signal as shown in the third row in FIG. 2 is input to the acceleration sensor 21 from when the count number N reaches the reference count number Nt until the primary check ends. As a result, the acceleration sensor 21 starts generating the output signal when the count number N reaches the reference count number Nt, and ends generating the output signal when the primary check ends.

  Further, the output signal generation unit 224 inputs an output signal output from the acceleration sensor 21 when a virtual failure diagnosis signal is input to the acceleration sensor 21. The output signal output from the acceleration sensor 21 rises gently after the output signal generation is started as shown in the lowermost stage of FIG. 2, then becomes a constant output value for a predetermined period, and falls after the end of the primary check.

  The output signal output unit 225 is connected to the above-described failure diagnosis unit 13 of the airbag ECU 1, and outputs the output signal generated by the output signal generation unit 224 to the failure diagnosis unit 13 of the airbag ECU 1. The output signal output unit 224 is an output terminal provided in the acceleration sensor unit 2.

  The operation when noise occurs in the vehicle occupant protection system configured as described above will be described. That is, the operation of the vehicle occupant protection system in a state where the reference signal generator 11 does not generate a reference signal and the count signal generator 12 does not generate a count signal will be described. Hereinafter, a case where short-period noise having the same cycle as the count signal is generated and a case where long-period noise same as the reference signal is generated will be described.

  First, a case where short period noise having the same period as the count signal is generated will be described. When short cycle noise having the same cycle as the count signal is generated, the short cycle noise is applied to the reference signal input unit 221 and the count signal input unit 222. That is, short-period noise is input to the reference signal input unit 221 and the count signal input unit 222. Then, the counter 223 counts the count number N of the count signal while the reference signal is input to the reference signal input unit 221. In this case, the counter 223 also counts the count number N of the count signal that is short-period noise. . However, since the reference signal, which is short-period noise, immediately stops, the count number N of the count signal does not increase. Therefore, the count number N of the count signal that is short-cycle noise does not reach 4, which is the reference count number Nt. Then, since the output signal generation unit 224 does not output the reference signal to the acceleration sensor 21, the malfunction of the acceleration sensor 21 does not occur.

  Next, a case where long period noise having the same period as the reference signal is generated will be described. When long-period noise having the same cycle as that of the reference signal is generated, the long-period noise is applied to the reference signal input unit 221 and the count signal input unit 222. That is, long-period noise is input to the reference signal input unit 221 and the count signal input unit 222. Then, the counter 223 counts the count number N of the count signal while the reference signal is input to the reference signal input unit 221. In this case as well, the counter 223 counts the count number N of the count signal that is long-period noise. . However, since the reference signal is generated, the count number N of the count signal, which is long-period noise, does not increase even though the count is continued. When the time further elapses, the reference signal that is long-period noise stops, and the count number N of the count signal does not increase. Therefore, the count number N of the count signal, which is long-period noise, does not reach 4, which is the reference count number Nt. Then, since the output signal generation unit 224 does not output the reference signal to the acceleration sensor 21, the malfunction of the acceleration sensor 21 does not occur.

  As described above, malfunction of failure diagnosis of the acceleration sensor 21 can be prevented even if any period of noise such as short period noise or long period noise occurs.

  In the above-described embodiment, the acceleration sensor is described as an example of the airbag sensor. However, the present invention is not limited to this. For example, any sensor used in an airbag system such as a load sensor or a pressure sensor may be used.

It is a figure which shows the structure of the passenger | crew protection system for vehicles. The time chart of each signal is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Airbag ECU, 11 ... Reference signal generation part (reference signal generation means), 12 ... Count signal generation part (count signal generation means), 13 ... Failure diagnosis part (failure diagnosis means) 2 Acceleration sensor unit 21 Acceleration sensor (airbag sensor) 22 Sensor control unit 221 Reference signal input unit 222 Count signal input unit 223 ..Counter (counting means), 224... Output signal generating section (output signal generating means), 225.

Claims (4)

An airbag sensor;
A reference signal generating means for generating a reference signal which is a signal for diagnosing a failure of the airbag sensor and having a predetermined period ;
Output signal generating means for generating an output signal of the airbag sensor based on the reference signal;
Failure diagnosis means for performing failure diagnosis of the airbag sensor based on the output signal;
In a vehicle occupant protection system comprising:
Further, a condition signal that generates a condition signal that is a condition for starting generation of the output signal based on a first signal that is a signal different from the reference signal and having a period different from the predetermined period of the reference signal With generating means,
The vehicle occupant protection system, wherein the output signal generation means generates the output signal based on the reference signal when the condition signal satisfies a predetermined condition. The vehicle occupant protection system according to claim 1, wherein the first signal is a signal having a cycle shorter than the predetermined cycle of the reference signal. The condition signal generating means includes
Count signal generating means for generating the first signal that is a periodic signal that can be counted during a predetermined time ;
Counting means for outputting the condition signal with a said count number counted to count the number of counting of the predetermined time of the first signal generated between,
With
The output signal generation unit generates the output signal based on the reference signal when the count number counted by the counting unit reaches a predetermined reference count number stored in advance. The vehicle occupant protection system according to claim 1. 4. The vehicle occupant protection system according to claim 3, wherein the counting means counts the count number of the first signal generated while the reference signal is generated.

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