Electronic control device and diagnosis method of electronic control device

Provided is an electronic control device including a timer that operates during a key-off time period, the electronic control device having high reliability to diagnose whether the timer is normally operated even during the key-off time period. The electronic control device includes a first power supply unit to which a battery voltage is always supplied as a power supply voltage, the first power supply unit including a first timer that measures a key-off time period, a diagnostic timer different from the first timer, and a first timer diagnosis unit that compares a timer value of the first timer with that of the diagnostic timer during the key-off time period.

TECHNICAL FIELD

The present invention relates to a configuration of an electronic control device and a diagnosis method thereof, and particularly relates to a technique that is effectively applicable to an electronic control device for a vehicle that requires high reliability and safety (fail-safe function).

BACKGROUND ART

In an electronic control device, a timer is used for various purposes. In an electronic control device for a vehicle, a timer is used in diagnosing several sensors and diagnosing parts of the vehicle every predetermined time interval while the vehicle is stopped.

For example, the timer mounted on the electronic control device is used to diagnose whether a temperature sensor (water temperature sensor) measuring a temperature of cooling water is normally operated. The temperature of the cooling water, which has risen during the operation of the vehicle, gradually decreases over time during a key-off time period when the vehicle is stopped. By comparing how much the water temperature of the cooling water measured by the water temperature sensor decreases relative to the key-off time period of the vehicle, it can be diagnosed whether the water temperature sensor is normally operated. In order to diagnose the water temperature sensor, it is necessary to diagnose whether the timer counting a key-off time period is normally operated.

In addition, the timer is used to regularly diagnose vehicle parts every predetermined time interval while the vehicle is stopped. A key-off time period is measured by the timer and the electronic control device is activated every predetermined time interval to perform the diagnosis of the vehicle parts.

In this way, various vehicle parts are diagnosed to safely operate the vehicle, and an engine control device also uses a timer that measures a key-off time period to perform various kinds of diagnosis. In order to reliably diagnose these vehicle parts, it is important to diagnose whether the timer operating during the key-off time period is normally operated.

An example of a conventional technique for diagnosing operation of the timer, which operates during the key-off time period, includes a technique as in PTL 1. PTL 1 discloses “an electronic control device including a control unit operated or stopped according to a power supply status that depends on how a power switch is changed over and a time measurement unit measuring a time continuously regardless of whether the control unit is operated or stopped, the control unit having an internal timer by which a time is measured during a predetermined time period to determine that the time measurement unit is abnormal based on the time measured by the time measurement unit in the predetermined time period”. The timer having operated during the key-off time period is operated during a key-on time period as well to compare the timer relative to the internal timer of the microcomputer during the key-on time period every predetermined time interval, thereby diagnosing the operation of the timer. When the timer fails, diagnosis of sensor failure is prohibited.

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

According to PTL 1, the timer that measures a time during the key-off period is operated during a key-on time period to perform diagnosis. However, it is not possible to diagnose whether the timer is normally operated during the key-off time period, which is essentially necessary. That is, the technique according to PTL 1 is not capable of detecting abnormality such as a temporary timer stop function during the key-off time period or a defect occurring only during the key-off time period. In such a state, if a timer value obtained during the key-off time period is used in diagnosing vehicle parts related to the key-off time period, the vehicle parts may sometimes be abnormally diagnosed.

An object of the present invention is to provide an electronic control device including a timer that operates during a key-off time period, the electronic control device having high reliability to diagnose whether the timer is normally operated even during the key-off time period, and a diagnosis method thereof.

Solution to Problem

According to the present invention for solving the aforementioned problems, an electronic control device includes a first power supply unit to which a battery voltage is always supplied as a power supply voltage. The first power supply unit includes: a first timer that measures a key-off time period; a diagnostic timer different from the first timer; and a first timer diagnosis unit that compares a timer value of the first timer with that of the diagnostic timer during the key-off time period.

According to the present invention, a diagnosis method of an electronic control device includes: a step (a) of turning off an ignition signal; a step (b) of starting a first timer and a diagnostic timer of a first power supply unit; a step (c) of shutting down a second power supply unit and a microcomputer; a step of (d) counting up respective timer values of the first timer and the diagnostic timer at predetermined time intervals during a key-off time period; a step (e) of comparing the first timer and the diagnostic timer every predetermined count cycle; and a step (f) of determining whether or not a change amount of a timer value of each of the first timer and the diagnostic timer is within a predetermined range. In the step (f), if the change amount of the timer value of each of the first timer and the diagnostic timer is within the predetermined range, the first timer is determined as being normal, and if the change amount of the timer value of each of the first timer and the diagnostic timer is beyond the predetermined range, the first timer is determined as being abnormal.

Advantageous Effects of Invention

According to the present invention, an electronic control device including a timer that operates during a key-off time period, the electronic control device having high reliability to diagnose whether the timer is normally operated even during the key-off time period, and a diagnosis method thereof can be provided.

Accordingly, it is possible to reliably diagnose the timer operating during the key-off time period and the vehicle parts controlled based thereon.

Other problems, configurations, and effects that are not described above will be apparent from the following description of embodiments.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that in respective drawings, the same reference numerals are given to the same components and the detailed description of overlapping portions will be omitted. In addition, respective configuration diagrams ofFIGS.1through5and respective flowcharts ofFIGS.6through8are examples of the embodiments according to the present invention and do not limit the claims.

First Embodiment

An electronic control device according to a first embodiment of the present invention will be described with reference toFIG.1.FIG.1is a minimum circuit configuration according to the present invention and illustrates a configuration of a first power supply unit10, which is a part of the electronic control device.

InFIG.1, a battery32and a first power supply unit10, to which the battery32is always connected and a battery voltage is always supplied as a power supply voltage, are included. The first power supply unit10includes a timer11for measuring a key-off time period, a diagnostic timer12, and a timer diagnosis unit13comparing a timer value of the timer11and a timer value of the diagnostic timer12with each other to diagnose whether each of the timers is normally operated.

The operation of the timer11for measuring a key-off time period is diagnosed by the timer diagnosis unit13at predetermined time intervals during the key-off time period. When either the timer11or the diagnostic timer12deteriorates in timer accuracy or stops due to its failure, a diagnosis result as abnormality is left in the timer diagnosis unit13. The electronic control device including the first power supply unit10detects the abnormality of the timer11or the diagnostic timer12by reading out the diagnosis result as abnormality from the timer diagnosis unit13after a key-on time period recommences.

In addition, if there is no diagnosis result as abnormality, the timer11is not abnormally operated during the entire key-off time period, and the value of the timer11is a normal value, which allows the electronic control device to diagnose vehicle parts related to the key-off time period.

Here, the diagnosis of the timer may be continuously performed during the key-on time period as well as during the key-off time period. When abnormality of the timer occurs during the key-on time period, diagnosis as abnormality may be retained in the timer diagnosis unit13and detected by the electronic control device likewise.

As described above, the electronic control device in this embodiment includes a first power supply unit10to which a battery voltage of the battery32is always supplied as a power supply voltage, and the first power supply unit10includes a first timer11measuring a key-off time period, a diagnostic timer12different from the first timer11, and a first timer diagnosis unit13comparing a timer value of the first timer11with that of the diagnostic timer12during the key-off time period.

By comparing the first timer11and the diagnostic timer12during the key-off time period, it is possible to diagnose mutual operation between the timers, thereby diagnosing operation of the timer that measures the key-off time period.

Second Embodiment

An electronic control device according to a second embodiment of the present invention will be described with reference toFIGS.2,6, and8.FIG.2illustrates a circuit configuration of the electronic control device in this embodiment.FIG.6illustrates a flowchart of timer diagnosis of the electronic control device in this embodiment. In addition,FIG.8illustrates a flowchart after a second power supply unit and a microcomputer of the electronic control device in this embodiment are started.

InFIG.2, a battery32, an electronic control device30, and a power relay31are included. The electronic control device30includes a first power supply unit10always connected to the battery32to be supplied with power, a second power supply unit20supplied with power from the battery32through the power relay31controlled to be turned on or off based on an ignition signal IG, and a microcomputer40.

The first power supply unit10includes a first timer11for measuring a key-off time period, a diagnostic timer12, a first timer diagnosis unit13, and a start signal generation unit19.

The second power supply unit20includes a start unit21for starting the second power supply unit20, a power generation unit23for generating power to a control unit including the microcomputer40, and a communication unit22.

The second power supply unit20is started based on an ignition signal IG and a battery voltage supplied from the battery32through the power relay31turned on by the ignition signal IG. After the second power supply unit20is started, a power supply voltage is supplied to the microcomputer40by the power generation unit23. The power-supplied microcomputer40can detect a timer diagnosis result by communicating with the first power supply unit10through the communication unit22.

Here, as in an example of a flowchart for the electronic control device illustrated inFIG.6, when the ignition signal IG is turned off, the microcomputer40starts the first timer11and the diagnostic timer12through the communication unit22, and subsequently, shuts down the second power supply unit20and the microcomputer40.

During the key-off time period, the first timer11and the diagnostic timer12count up timer values at predetermined time intervals. The first timer diagnosis unit13compares the first timer11and the diagnostic timer12every predetermined count cycle. In the example ofFIG.6, if a change amount of each timer value from a compared timer value every 60 seconds is between 55 seconds and 65 seconds, the timer is diagnosed as being normal (Yes). Otherwise, the timer is diagnosed as being abnormal (No).

In case of diagnosis as normality (Yes), diagnosis is repeatedly and continuously performed in the same way every 60 seconds, and the diagnosis of the timer is performed during the key-off time period.

On the other hand, in case of diagnosis as abnormality (No), an NG flag as the diagnosis of the first timer is recorded in the first timer diagnosis unit13. When a key-on time period commences, if a start setting of the second power supply unit20is in an on-state as a setting for diagnosis as abnormality from the microcomputer40, the second power supply unit20is started in response to a start signal from the start signal generation unit19according to the determination of diagnosis as abnormality. If the start setting is in an off-state, the diagnosis of the timer is continued until the ignition signal IG is turned on.

In an example of a flowchart after the second power supply unit and the microcomputer are started as illustrated inFIG.8, immediately after the ignition signal IG is turned on and the second power supply unit20and the microcomputer40are started, the timer diagnosis result is read out from the first timer diagnosis unit13. In case of diagnosis as abnormality (there is an NG flag: Yes), it can be selected not to perform diagnosis of vehicle parts controlled based on the first timer11, thereby preventing erroneous diagnosis of the vehicle parts.

On the other hand, in case of diagnosis as normality (there is no NG flag: No), reliable diagnosis can be performed by performing diagnosis of the vehicle parts controlled based on the first timer11during the key-off time period.

As described above, the electronic control device in this embodiment includes a second power supply unit20to which a battery voltage of the battery32is supplied as a power supply voltage through the power relay31controlled to be turned on or off based on the ignition signal IG and a start signal generation unit19generating a start signal for the second power supply unit20based on a comparison result of the first timer diagnosis unit13.

Accordingly, when the first timer11is abnormal as a result of diagnosis, the second power supply unit20can be started in response to the start signal from the start signal generation unit19.

It should be noted that the first timer11can be used as an ignition-off timer that measures an ignition-off time period to diagnose accuracy of the off timer.

Alternatively, the first timer11can be used as a wake-up timer for starting the second power supply unit20after a predetermined key-off time period to diagnose accuracy of the wake-up timer.

In addition, the first power supply unit10(first timer diagnosis unit13) is connected to the microcomputer40through the communication unit22to notify the microcomputer40of a diagnosis result obtained by the first timer diagnosis unit13during the key-off time period after a key-on time period commences. The first timer diagnosis unit13compares a timer value stored in the microcomputer40with those of the first timer11and the diagnostic timer12during the key-on time period.

The diagnosis result obtained during the key-off time period is left in the first timer diagnosis unit13, and when the microcomputer is started, for example, after a key-on time period recommences, the microcomputer40can be notified of the failure of the timer having occurred during the key-off time period. Accordingly, it is possible to determine whether or not to perform diagnosis of the vehicle parts related to the key-off time period, and it is possible to prevent erroneous diagnosis that may occur if the diagnosis is performed.

In addition, when the ignition-off timer fails, the diagnostic timer12can be substituted as a second ignition-off timer that measures a key-off time period. When the ignition-off timer that measures a key-off time period fails, the diagnostic timer12can be diverted as an ignition-off timer and used for diagnosing the vehicle parts related to the key-off time period.

Third Embodiment

An electronic control device according to a third embodiment of the present invention will be described with reference toFIGS.3and7.

FIG.3illustrates a circuit configuration of the electronic control device in this embodiment.FIG.7illustrates a flowchart of timer diagnosis of the electronic control device in this embodiment.

InFIG.3, a second timer15(wake timer) and a second timer diagnosis unit18of the first power supply unit10are added to the circuit configuration ofFIG.2according to the second embodiment, and the other components identical to those inFIG.2operate in the same manner as in the second embodiment.

Here, the second timer15(wake timer) is a wake-up timer, which is a timer set by the microcomputer40to start the second power supply unit20every predetermined set time during the key-on time period.

As in an example of a flowchart for the electronic control device illustrated inFIG.7, when the ignition signal IG is turned off, the microcomputer40starts the second timer15(wake timer) and the diagnostic timer12through the communication unit22, and subsequently, shuts down the second power supply unit20and the microcomputer40.

During the key-off time period, the second timer15(wake timer) and the diagnostic timer12count up timer values at predetermined time intervals. The second timer diagnosis unit18compares the second timer15(wake timer) and the diagnostic timer12every predetermined count cycle. In the example ofFIG.7, if a change amount of each timer value from a compared timer value every 60 seconds is between 55 seconds and 65 seconds, the timer is diagnosed as being normal (Yes). Otherwise, the timer is diagnosed as being abnormal (No).

In case of diagnosis as normality (Yes), diagnosis is repeatedly and continuously performed in the same way every 60 seconds, and the diagnosis of the timer is performed during the key-off time period, until the second power supply unit20is started after a value of the second timer15(wake timer) reaches a wake set value or the ignition signal IG is turned on.

When the wake-up timer value of the second timer15(wake timer) reaches the set value (Yes), the second power supply unit20is started. Alternatively, when the ignition signal IG is turned on, the second power supply unit20is started.

On the other hand, in case of diagnosis as abnormality (No), an NG flag as the diagnosis of the second timer is recorded in the second timer diagnosis unit18. When a key-on time period commences, if a start setting of the second power supply unit20is in an on-state as a setting for diagnosis as abnormality from the microcomputer40, the second power supply unit20is started in response to a start signal from the start signal generation unit19according to the determination of diagnosis as abnormality. If the start setting is in an off-state, the diagnosis of the timer is continued until the ignition signal IG is turned on or the wake-up timer value of the second timer15(wake timer) reaches the set value.

In this way, by continuously diagnosing the wake-up timer as the second timer15(wake timer) during the key-off time period, diagnosis as abnormality can be detected when the second timer15(wake timer) or the diagnostic timer12is abnormal during the key-off time period. Even if the wake-up timer (second timer15) stops due to failure, the failure of the timer can be detected by starting the second power supply unit20, while preventing the electronic control device from having a starting defect.

As described above, in the electronic control device in this embodiment, the first power supply unit10includes a second timer15for starting the second power supply unit20after a predetermined key-off time period and a second timer diagnosis unit18comparing the second timer15and the diagnostic timer12during the key-off time period, and the start signal generation unit19generates a start signal for the second power supply unit20based on diagnosis results of the first timer diagnosis unit17and the second timer diagnosis unit18.

In addition, when the wake-up timer (second timer15) or the diagnostic timer12fails, abnormality is detected by the first timer diagnosis unit17, and accordingly, the second power supply unit20is started.

Accordingly, for example, even if the second timer15(wake-up timer) stops due to failure, which makes it impossible to start the second power supply unit20, the second power supply unit20can be started by a start signal of the start signal generation unit19resulting from detection of abnormality by the diagnostic units (first timer diagnosis unit17and second timer diagnosis unit18). Thus, a starting defect can be avoided, such that the electronic control device performs control at the time of failure.

Fourth Embodiment

An electronic control device according to a fourth embodiment of the present invention will be described with reference toFIG.4.FIG.4illustrates a circuit configuration of the electronic control device in this embodiment.

InFIG.4, an oscillator16of the first power supply unit10is added to the circuit configuration ofFIG.3according to the third embodiment, and the other components identical to those inFIG.3operate in the same manner as in the third embodiment.

In the configuration ofFIG.4, the first timer14, the second timer15, and the diagnostic timer12share the oscillator16, on which time measurement is based, in common. By using the oscillator16in common for each timer as in this embodiment (FIG.4), there is a merit in that a circuit scale can be reduced. However, if the oscillator16fails, all of the first timer14, the second timer15, and the diagnostic timer12stop, and a failure mode occurs and accordingly timer diagnosis cannot be performed.

Fifth Embodiment

An electronic control device according to a fifth embodiment of the present invention will be described with reference toFIG.5.FIG.5illustrates a circuit configuration of the electronic control device in this embodiment.

InFIG.5, a diagnostic oscillator24is further added to the circuit configuration ofFIG.4according to the fourth embodiment, and the other components identical to those inFIG.4operate in the same manner as in the fourth embodiment.

In the configuration ofFIG.5, the diagnostic oscillator24is used only for the diagnostic timer12as its basis. By using the diagnostic oscillator24only for the diagnostic timer12, even if the oscillator16fails or the diagnostic oscillator24fails, abnormality can be detected through timer diagnosis, thereby improving a diagnosis rate concerning diagnosis as failure.

In each of the above-described embodiments, for example, the first power supply unit10and the second power supply unit20can be constituted by a single integrated circuit such as an application specific integrated circuit (ASIC), thereby reducing a cost of the electronic control device.

In addition, if there is abnormality as a diagnosis result of the first timer diagnosis unit13or17, the diagnosis of the vehicle using the first timer11can be stopped after a key-on time period commences, thereby not diagnosing vehicle parts related to the key-off time period to prevent erroneous diagnosis.

It should be noted that the present invention is not limited to the above-described embodiments, and includes various modifications.

For example, the above-described embodiments have been described in detail in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to having all the configurations described above. In addition, a part of the configuration of one embodiment may be replaced with that of the configuration of another embodiment, and the configuration of one embodiment may be added to the configuration of another embodiment. In addition, with respect to a part of the configuration of each embodiment, it is possible to perform addition of another configuration, deletion, or replacement with another configuration.

REFERENCE SIGNS LIST