JPH09226514A - Diagnosis device of electronic control device for air bags system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect trouble of parts surely and also part trouble in an early stage at the usual use time, in a running test at the production time. SOLUTION: A cumulative operation time of a power source.backup circuit is memorized on E<2> PROM.5. A trouble detection threshold value is calculated by a micro-computer 2 based on the characteristic showing the cumulative operation time and parts trouble. Then, the capacity value of a condenser C as one sample of part is calculated by the micro-computer 2. The microcomputer 2 compares the calculated trouble detection threshold value with the capacity value and when the capacity value is less than the trouble detection threshold value, it is judged that the condenser C has trouble and this is recorded on a record block 3 and also warning lamp 4 is lightened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diagnostic device for detecting a defect or a failure of a component requiring a long-term guarantee among components of an electronic control device for an airbag system.

[0002]

2. Description of the Related Art An automobile air bag system is an electronic control unit including a collision determination block for detecting a collision of the automobile, an ignition block for inflating an air bag at the time of collision, a power supply / backup block for supplying electric power to each part of the system. Is controlled by. Then, the electronic control unit detects the failure of the component parts constituting the electronic control unit itself by the self-diagnosis function at any time. Here, the self-diagnosis function is a function of executing a diagnosis program by using a microcomputer incorporated in the electronic control unit at the time of starting or traveling of the automobile to detect a failure of the above-mentioned component parts. . The failure detection of the capacitor using the self-diagnosis function will be described below, taking the backup capacitor provided in the power supply / backup block as an example of the component.

FIG. 3 is a graph showing a cumulative operating time of a general capacitor and a change in the capacitance value with the cumulative operating time. As shown in this figure, the capacitor deteriorates due to its operation and its capacitance value decreases. Therefore, the microcomputer constantly measures the capacitance value of the capacitor during operation, and when the capacitance value becomes equal to or less than the constant value (fault detection threshold value) shown in FIG. 3, the warning lamp is turned on as a fault. For example, in the example shown in FIG. 3, the microcomputer sets the failure detection threshold to the normal capacitor (capacitor a).
Is set to 70% of the initial capacitance value (3900 [μF]), that is, 2730 [μF], and when the capacitance value of the capacitor a becomes equal to or lower than the failure detection threshold value, it is determined that a failure has occurred.

By the way, the above-mentioned self-diagnosis is originally carried out to detect a failure of the above-mentioned component parts due to deterioration during use after the manufactured automobile is in the hands of the user. Separately, before the car is handed over to the user, that is, at the time of manufacture of the manufacturer, a test of running the electronic control unit for a certain period of time continuously in order to detect an initial failure of the component, that is, a running Tests are also conducted.

In the conventional running test, a dedicated diagnostic device was used to diagnose each part of the electronic device during the running test, but recently, in order to keep the equipment cost of the factory low, the above-mentioned exclusive test is also performed in the running test. There is an increasing number of cases in which the initial failure is detected by using the self-diagnosis function by the built-in microcomputer instead of the diagnosis device. For example, in the example shown in FIG.
Has an initial capacitance value of 2600 [μF], which is equal to or lower than the failure detection threshold value (2730 [μF]).
In a running test, it is judged as a defective product.

[0006]

By the way, in the above-mentioned conventional diagnostic device, when the diagnostic device is used for detecting an initial defect in a running test, it is more difficult to detect than when a dedicated diagnostic device is used. The detection accuracy of good products is low,
There was a problem that.

For example, taking the above-mentioned capacitor diagnosis as an example (see FIG. 3), as shown in the capacitor c, the capacitance value at the initial manufacturing is 75% (that is, 2%) of the normal product.
925 [μF]), the capacitance value does not fall below the failure detection threshold value in the running test.
Therefore, even though the capacity value is 75% of the normal product,
The capacitor is not detected as a defective product. However, the capacitance value of the capacitor c reaches the failure detection threshold value after the running test is completed, in a cumulative operating time much shorter than the cumulative operating time of the capacitor a,
It will be judged as a failure. That is, although not detected by the self-diagnosis function, the capacitor c is substantially a defective product.

The present invention has been made under such a background, and it is possible to reliably detect a defect of a component in a running test at the time of manufacture, and at the same time, to prevent failure of the component during normal use. An object of the present invention is to provide a diagnostic device for an electronic control device for an airbag system, which can be detected early.

[0009]

According to the first aspect of the present invention,
The measuring means for measuring the characteristics of the constituent parts of the electronic control unit of the airbag system, the measured value measured by the measuring means, and the failure detection threshold value for the measured value are used as the constituent parts. Of the defect detection threshold value, the failure detection threshold value is changed according to the cumulative operation time obtained by the time measurement means, and the determination means for determining the failure or failure of the electronic control device. And a control means.

According to a second aspect of the present invention, there is provided a diagnostic device for an electronic control unit for an airbag system according to the first aspect,
It is characterized by comprising recording means for recording the determination result by the determination means, or informing means for informing the determination result.

According to a third aspect of the present invention, in the diagnostic device for an electronic control device for an air bag system according to the first or second aspect, the constituent parts are provided on a power supply / backup circuit of the air bag system. The capacitor is characterized in that the characteristic is the capacitance of the capacitor.

According to a fourth aspect of the present invention, in the diagnostic device for an electronic control unit for an air bag system according to any one of the first to third aspects, the determination means determines that the measured value is the failure detection threshold. If the value is less than or equal to the value, it is determined that the component is defective or defective.

According to a fifth aspect of the present invention, in the diagnostic device for an electronic control device for an airbag system according to any one of the first to fourth aspects, the time measuring means indicates a cumulative operating time of the electronic control device. The accumulated operating time storage means for storing the accumulated operating time, and the accumulated operating time reading means for reading the accumulated operating time so far from the accumulated operating time storage means at the start of operation of the electronic control device and the accumulated operating time reading means. By updating the cumulative operating time according to the passage of time, a cumulative operating time updating means for obtaining the current cumulative operating time, and at the end of the operation of the electronic control unit, the current cumulative operating time is stored in the cumulative operating time storage. And a cumulative operating time writing means for writing to the means.

According to a sixth aspect of the present invention, in the diagnostic apparatus for an electronic control device for an airbag system according to any one of the first to fifth aspects, the control means is the cumulative operating time obtained by the timekeeping means. Is substituted into a predetermined calculation formula to calculate the failure detection threshold value.

According to a seventh aspect of the present invention, in the diagnostic apparatus for an electronic control device for an airbag system according to any one of the first to fifth aspects, the control means has a failure corresponding to each cumulative operating time. Failure detection threshold value storage means for storing the detection threshold value and failure detection threshold value for reading out the failure detection threshold value corresponding to the cumulative operating time obtained by the time counting means from the failure detection threshold value storage means. And a reading means.

[0016]

DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. Numerical values such as capacitance value, voltage, and cumulative operating time in the following description are merely specific examples and do not limit the content of the invention. FIG. 1 is a block diagram showing a configuration example of a diagnostic device according to an embodiment of the present invention.

In this figure, the power supply / backup circuit 1 is an electronic circuit equipped with a capacitor C which is the object of diagnosis of this apparatus. In addition, the power supply except the above-mentioned capacitor C
The configuration and the operation of the backup circuit 1 itself are not directly related to the configuration and the operation of the present apparatus, and thus the description thereof will be omitted. The capacitance value of the capacitor C is 3900 [μF] when the capacitor C is a normal product.
Further, in order to read the voltage of the capacitor C, the + terminal of the capacitor C is connected to the microcomputer 2.

The microcomputer 2 is a C which has an A / D converter built-in.
It is a PU (Central Processing Unit). The microcomputer 2 is A /
The voltage of the capacitor C is read using the D converter, and the capacitance value of the capacitor C is calculated based on the voltage. Then, the microcomputer 2 determines whether or not the calculated capacitance value is less than or equal to the failure detection threshold value. If the capacitance value is less than or equal to the failure detection threshold value, the capacitor C is defective (or has a failure value). ) Is diagnosed. The details of the diagnosis process will be described later in the description of the operation of the present apparatus.

The recording block 3 is an electrically readable / writable IC memory (RAM, E ² PROM, flash ROM, etc.) and records and holds various data relating to the electronic control unit of the airbag system. That is, in the present embodiment, when the microcomputer 2 detects a defect (or failure) of the capacitor C, it writes it in the recording block 3. The warning lamp 4 is turned on by an input signal from the microcomputer 2 to notify an inspector or a driver of a defect (or failure) of the capacitor C. E ² PROM 5
It is an electrically readable / writable IC memory and stores the cumulative operating time of the power supply / backup circuit 1 calculated by the microcomputer 2.

Next, the operation of the diagnostic device having the above configuration will be described. There are two usage environments for this device: a running test, which is a manufacturing test in a factory, and a self-diagnosis test, which is performed during normal operation after the car is in the hands of the user. Also, the operation of this device is the same.

First, when the inspector (or driver) turns on an ignition switch (not shown), the microcomputer 2
The cumulative operating time up to this point is read from the E ² PROM5. After that, an oscillator (not shown) inputs a clock pulse to the microcomputer 2 until the ignition switch is turned off. Therefore, the microcomputer 2 counts time based on the clock pulse, and the accumulated operating time is incremented at regular intervals. Is incremented.

On the other hand, when the microcomputer 2 reads the above-mentioned accumulated operating time from the E ² PROM 5, it calculates a failure detection threshold value based on the accumulated operating time. At this time, the failure detection threshold value is calculated by the following equation (1) or (2). When cumulative operating time is less than 3000 hours (fault detection threshold value) = (initial threshold value) −0.223 × (cumulative operating time) (1) When cumulative operating time is 3000 hours or more (fault Detection threshold value) = (initial value of capacitance of capacitor C) × 0.7 (2) Here, as an example of the numerical value, the initial threshold value is 3400.
[ΜF], the initial value of the capacitance of the capacitor C is 3900
[ΜF]. As a result, the failure detection threshold value calculated by this device changes as shown in FIG. 2 corresponding to the cumulative operating time.

Next, the microcomputer 2 carries out processing in the following order of to obtain the capacitance value of the capacitor C. The capacitor C is charged until the voltage of the capacitor C reaches 18 [V]. The capacitor C is caused to discharge. The discharge current at this time is 50 [mA]. The voltage of the capacitor C is monitored.
The discharge time required to decrease from [V] to 16.5 [V] is measured. The measured discharge time is substituted into the following formula (3) to calculate the capacitance value of the capacitor C. C = (IT) / ΔV (3) In this formula, C is the capacitance value of the capacitor (unit [μ
F]), I is the discharge current value of the capacitor (unit [m
A]), T is the discharge time of the capacitor (unit [mS]),
ΔV is a variable voltage value (unit [V]) of the capacitor.

For example, when the voltage of the capacitor C drops from 18 [V] to 16.5 [V] during discharging, it is 90
If it takes [mS], from the above formula (3), (50 × 90) / (18-16.5) = 4500 / 1.5 = 3000, and the capacitance value of the capacitor C is 3000 [μF]. become.

The microcomputer 2 compares the calculated failure detection threshold value with the capacitance value, and if the capacity value is equal to or less than the failure detection threshold value, the capacitor C is determined to be a failure, and this is recorded in the recording block 3 And the warning lamp 4 is turned on.

By the above operation, for example, the capacitance value of the capacitor at the time of manufacture is 75% of that of a normal product, that is,
In the case of 2925 [μF], as shown in FIG. 3, in the conventional technique, the capacitance value does not fall below the failure detection threshold value in the running test at the time of manufacturing, so that the defect (capacitance value of the capacitor c is insufficient). ) Cannot be detected in the running test, but as shown in FIG. 2, in this device, the failure detection threshold value is changed according to the accumulated operating time. You can

Finally, a running test (or driving)
Then, when the inspector (or driver) turns off the ignition switch, the microcomputer 2 writes the cumulative operating time, which is incremented at every constant time, in the E ² PROM. This is the end of the description of the operation of the diagnostic device having the above configuration.

Next, the correspondence between the claimed invention and this embodiment will be described. Measuring means: Microcomputer 2 Judging means: Microcomputer 2 Timekeeping means: Microcomputer 2, E ² PROM / 5 cumulative operating time storage means: E ² PROM / 5 Cumulative operating time reading means: Microcomputer 2 Cumulative operating time updating means ...... Microcomputer 2 Cumulative operating time writing means ...... Microcomputer 2 control means ...... Microcomputer 2 recording means ...... Recording block 3 Notification means ...... Warning lamp 4

The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and the design can be changed without departing from the gist of the present invention. Even if there is, it is included in the present invention. For example, in the above-described one embodiment, the backup capacitor provided in the power supply / backup circuit of the airbag system is taken as an example of the diagnosis target of this device, and the detection of a defect (or failure detection) of the capacitor will be described. However, the object to be diagnosed by the present apparatus is not limited to this, and the diagnosis of other components (ceramic oscillator etc.) of other electronic circuits can be performed by the same processing.

Further, in the embodiment, when the failure detection threshold value corresponding to the cumulative operating time is obtained, the above equation (1) or (2) is used as the calculation expression, but the failure detection threshold value is not used. The calculation formula of is not limited to this.
Furthermore, instead of using a calculation formula when obtaining the failure detection threshold value, instead of this, a table is prepared in which the failure detection threshold value obtained by the experiment is stored in association with each cumulative operating time, and from this table, the current A method of reading out the failure detection threshold value corresponding to the cumulative operating time of is also conceivable.

In the embodiment, when the cumulative operating time of the power supply / backup circuit 1 is obtained, the cumulative operating time is read from the E ² PROM 5 when the ignition switch is turned on, and the cumulative operating time is incremented during operation. Then, the cumulative operating time incremented when the ignition switch is turned off is stored in the E ² PROM 5; however, the method for measuring the cumulative operating time is not limited to this.
For example, a dedicated register for holding the cumulative operating time may be prepared in the microcomputer 2, and the register may be backed up by a battery with an internal battery.

Further, in the embodiment, an example in which the diagnosis is performed when the ignition switch is turned on has been described.
The timing and timing at which the diagnosis is performed are not limited to this, and the timing and timing at which the diagnosis is performed include performing the diagnosis at regular intervals while the ignition switch is turned on (that is, while the power supply / backup circuit is operating). Various types are possible.

[0033]

As described above, according to the present invention, it is possible to reliably detect a defect of a component in a running test during manufacturing, and it is possible to promptly detect the failure of the component during normal use. Can be detected. Further, according to the present invention, in the quality inspection at the time of production, it is possible to secure a high inspection capability while reducing the equipment required for the inspection.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration example of a diagnostic device for an electronic control device for an airbag system according to an embodiment of the present invention.

FIG. 2 is a graph showing how the capacitance value of a capacitor and a failure detection threshold change in the diagnostic device according to the same embodiment.

FIG. 3 is a graph showing how the capacitance value of a capacitor and a failure detection threshold change in a conventional diagnostic device.

[Explanation of symbols]

2 ... Microcomputer, 3 ... Recording block, 4 ... Warning lamp, 5 ... E ² PROM

Claims (7)

[Claims] 1. A measuring means for measuring characteristics of components constituting an electronic control unit of an airbag system, a measured value measured by the measuring means, and a magnitude of a failure detection threshold for the measured value. A determination unit that determines a defect or a failure of the component, a time counting unit that determines the cumulative operating time of the electronic control device up to the present, and the failure detection according to the cumulative operating time that the timing unit determines. A diagnostic device for an electronic control device for an airbag system, comprising: a control means for changing a threshold value. 2. The diagnostic device for an electronic control device for an air bag system according to claim 1, further comprising: a recording unit that records the determination result by the determination unit, or an informing unit that notifies the determination result. Diagnostic device for electronic control unit for airbag system. 3. A diagnostic device for an electronic control device for an airbag system according to claim 1, wherein the component is a capacitor provided on a power supply / backup circuit of the airbag system, A diagnostic device for an electronic control unit for an airbag system, wherein the characteristic is the capacitance of the capacitor. 4. The diagnostic device for an electronic control device for an air bag system according to claim 1, wherein the determination unit determines that the measured value is equal to or less than the failure detection threshold value. A diagnostic device for an electronic control unit for an air bag system, which is characterized by determining that a component is defective or defective. 5. The diagnostic device for an electronic control device for an airbag system according to claim 1, wherein the timekeeping means stores a cumulative operating time of the electronic control device. Means, a cumulative operating time reading means for reading the cumulative operating time so far from the cumulative operating time storage means at the start of operation of the electronic control unit, and a cumulative operating time read by the cumulative operating time reading means, A cumulative operating time updating unit that obtains the current cumulative operating time by updating according to the elapsed time, and a cumulative operating time that writes the current cumulative operating time to the cumulative operating time storage unit when the operation of the electronic control unit ends. A diagnostic device for an electronic control device for an airbag system, comprising: a writing means. 6. The diagnostic apparatus for an electronic control device for an airbag system according to claim 1, wherein the control unit uses a predetermined calculation formula to calculate the cumulative operating time calculated by the time measuring unit. A diagnostic device for an electronic control device for an airbag system, characterized in that the failure detection threshold value is calculated by substituting it. 7. The diagnostic device for an electronic control device for an airbag system according to claim 1, wherein the control means stores a failure detection threshold value corresponding to each cumulative operating time. And a failure detection threshold value reading means for reading from the failure detection threshold value storage means a failure detection threshold value corresponding to the cumulative operating time obtained by the time counting means. A diagnostic device for an electronic control unit for an airbag system, characterized by: