JP3531589B2 - Electronic control unit for engine control - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic control device, and more particularly, to an on-vehicle electronic control device using a timekeeping unit such as a clock IC that continuously measures time regardless of whether the microcomputer is activated or stopped. Is.

[0002]

2. Description of the Related Art For example, a vehicle-mounted electronic control device (vehicle-mounted EC
As U), the elapsed time is measured using a built-in timepiece IC, and the time when the ECU power is off, that is, the engine stop time (soak time) is calculated from various data from the timepiece IC. It is known that the time when an actuator failure occurs is stored.

Taking the failure judgment of the temperature sensor for detecting the engine cooling water temperature as an example, the engine cooling water temperature is lowered after a lapse of a fixed time after the engine is stopped, and the time during which the engine is stopped by using a clock IC is used. Measure progress. Then, the failure of the water temperature sensor is determined from the degree of decrease in the sensor detection value (water temperature) when a predetermined time elapses after the engine is stopped.

[0004]

However, in the above-mentioned prior art, when the timepiece IC is reset due to the interruption of power supply to the timepiece IC during the period when the ECU power is off, the time data of the timepiece IC is reset. Goes crazy.
For example, when the engine stop time (soak time) is calculated from the time data of the clock IC, the calculated time may be erroneously calculated, and it may not be possible to appropriately carry out the sensor failure determination or the like. That is, in the existing device in the related art, it is not possible to confirm the correctness of the time of the clock IC. Therefore, if the time data is distorted, various controls performed using the time data may be hindered. It was

The present invention has been made in view of the above problems, and its purpose is to provide a clock unit (clock I).
An object of the present invention is to provide an electronic control device capable of correctly recognizing even if the reset of C) occurs carelessly.

[0006]

According to a first aspect of the present invention, the control unit operates when the ignition switch is turned on to perform data calculation and control relating to engine control, and stops when the ignition switch is turned off. To do. The timer unit operates by being supplied with electric power from a power source of a system different from that of the control unit, and measures the time elapsed while the engine is stopped. Further, in particular, the control unit also performs a failure determination of the in-vehicle device.
A than, and is further determined by determining the presence or absence of the reset of the timer unit by indirectly or directly monitor the power supply state to the time measuring unit, wherein the timing unit is reset
In that case, the failure determination is not performed . In short, the clock IC
However, according to the present invention, by monitoring the power supply state to the timer unit, the control unit determines whether the timer unit is reset or not. Can be appropriately determined. As a result, even if the reset of the timekeeping unit occurs carelessly, it can be recognized correctly. In particular, according to the invention,
When it is determined that the clock unit has been reset,
Since no failure judgment is made, incorrect time data in the timekeeping section
The judgment result is not appropriate due to the use
Highly reliable failure determination without inconvenience
it can.

According to the second aspect of the present invention, the control unit determines whether or not the timekeeping unit has been reset during the stop period of the control unit when the control unit is started. Therefore, the engine is stopped (during the stop period of the control unit). Even if a reset of the clock unit occurs in), it can be recognized immediately after the control unit is activated. By performing the reset determination of the clock unit at the time of starting the control unit, it is possible to perform various kinds of control without error from the beginning of the start.

[0008] Here, as in claim 3 or claim 4, by providing a memory (standby RAM or the like) for holding the stored contents by the same power supply as the timekeeping unit and power supply from the power supply, It is possible to indirectly monitor the power supply state of the.

That is, according to the third aspect of the present invention, an electronic control device for monitoring a decrease in the power supply voltage using the data holding voltage of the memory, which is slightly higher than the reset voltage (minimum operating voltage) of the clock unit, as a threshold value. Therefore, the control unit determines whether or not the timekeeping unit is reset based on the history indicating that the power supply voltage of the memory has dropped below the data holding voltage. In this case, since the reset voltage of the timer unit and the data holding voltage of the memory are relatively close and “reset voltage <data holding voltage”, if the power supply voltage drops below the data holding voltage of the memory, It is highly possible that the two resets occurred at the same time. Therefore, from this, it is possible to make a reset determination of the time counting unit. Also in this case,
In general, a microcomputer provided with a memory such as a standby RAM has a voltage monitoring function that uses a data holding voltage as a threshold value in advance, and by using the existing configuration of the microcomputer, it is possible to add a new configuration without adding a new configuration. The device can be realized.

Further, according to the invention described in claim 4, the control section checks the data held in the memory, and judges from the check result whether or not the clock section is reset. in this case,
If it is determined that the data held in the memory has been destroyed,
It is considered that this is because the power supply voltage has dropped below the data holding voltage. Therefore, as described above, the reset voltage of the clock unit and the data holding voltage of the memory are relatively close to each other and "reset voltage <data holding voltage". Therefore, at the time of the above voltage drop, the reset of the clock unit also occurs at the same time. It is highly possible that Therefore, from this, it is possible to make a reset determination of the time counting unit.

Further, when the means for detecting the power supply voltage of the timer is provided and the reset of the timer is judged based on the detection result of the power supply voltage, the timer can be configured. It is possible to directly monitor the state of power supply to the power supply and make a reset determination of the timer. For example, the power supply voltage drop may be monitored by using the minimum operating voltage of the timer unit or a voltage value slightly higher than the minimum operating voltage as a threshold value.

According to the sixth aspect of the present invention, the failure of the water temperature sensor is determined based on the elapsed time during the engine stop and the detection value of the water temperature sensor at the engine start. In this case, when it is determined that the timekeeping unit has been reset, failure determination of the water temperature sensor is prohibited, which may cause inconvenience that the determination result is insufficient due to use of incorrect time data of the timekeeping unit. Therefore, highly reliable sensor failure determination can be performed.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an example of a vehicle-mounted control unit (ECU) mounted on a vehicle to perform engine control and other controls.

In FIG. 1, the ECU 10 is connected to a battery 21 by two power feed paths.
The battery power is supplied to the power supply IC 11 in 0 according to the ON / OFF of the IG switch 22, while the battery power is always supplied by another system. A starter device 24 is connected to the battery 21 via a starter switch 23.

The power supply IC 11 in the ECU 10 generates and outputs a main power supply and a sub power supply (both about 5 V in this embodiment), and always generates the sub power supply regardless of the ON / OFF state of the IG switch 22. At the same time, when the IG switch 22 is turned on (closed), main power is generated. Of these, the sub power supply is the clock IC 12 as a timekeeping unit.
And a standby RAM (hereinafter abbreviated as SRAM) 13 are supplied. As a result, the clock IC 12 can continuously measure time regardless of whether the IG switch 22 is on or off. In addition, the SRAM 13 is the IG switch 2
It is possible to retain the stored contents even when 2 is turned off.

The clock IC 12 internally divides the clock signal from the crystal oscillator, and counts "year, month, day, hour, minute, second" with a built-in counter. Once the time and date and time are set and activated once, the clock IC 12 continues to operate as long as power supply is continued, and accurate time data can be obtained by reading the internal value.

The main power source is supplied to a microcomputer (microcomputer) 14 and an EEPROM 15 as a control unit, and the microcomputer 14 is activated when the main power source is supplied. That is, when the IG switch 22 is turned on, the microcomputer 14 operates, and when the IG switch 22 is turned off, the microcomputer 14 stops. The microcomputer 14 is composed of a well-known logical operation circuit including a CPU and a memory, and executes various data operations and controls. In addition, the microcomputer 14
The time data held by the clock IC 12 is periodically read and the time data is stored in the SRAM 13 as needed.

The water temperature sensor 25 detects the temperature of the engine cooling water, and the detected value is taken into the ADC (AD converter) 14a in the microcomputer 14. The microcomputer 14 detects the engine cooling water temperature at each time from the detection value of the water temperature sensor 25. Further, when the microcomputer 14 carries out a failure diagnosis of the water temperature sensor 25 and determines that a failure has occurred, the EEPROM 1 outputs a failure code indicating the details of the failure.
Store in 5.

Next, the processing procedure of the microcomputer 14 relating to the failure determination of the water temperature sensor 25 will be described. FIG. 2 is a flowchart showing a failure determination routine of the water temperature sensor 25 which is executed when the microcomputer is started. It should be noted that the failure determination of the water temperature sensor 25 described here is based on the degree of decrease in the water temperature detection value at the engine start when the soak time (the time when the vehicle is left with the engine stopped) is a predetermined time or longer. 25 failures are diagnosed.

In addition to the processing shown in FIG.
The scheduled interrupt processing shown in FIG. 5 is executed. First, the interrupt process of FIG. 5 will be described. For example, the process of FIG. 5 is started every one second, and in step 401, the current time data (current time) of the clock IC 12 is set to “previous time”. In the following step 402, the previous time is stored in the SRAM.
Store in 13. According to the process of FIG. 5, the time data of the clock IC 12 is stored in the SRAM 13 as the “previous time” every one second during the normal operation of the engine. At this time, the previous time data in the SRAM 13 is overwritten each time. Therefore, when the engine is stopped (when the IG is off), the last stored last time data remains in the SRAM 13 and the data is retained even when the engine is stopped.

On the other hand, when FIG. 2 starts when the microcomputer 14 is started up, in step 101, the reset judgment of the timepiece IC 12 is performed. This reset determination determines whether or not there is a sign that the clock IC 12 has been reset before the microcomputer is activated (engine stop period), and is performed according to the process of FIG. 3 or FIG. 4, for example. However, the details will be described later.

In the following step 102, the above step 1
Based on the result of 01, it is determined whether or not the timepiece IC reset is confirmed. If the clock IC12 has been reset,
The present process is terminated without performing the subsequent failure determination process. If the clock IC 12 has not been reset, the failure determination process from step 103 is executed.

At step 103, the current time is read from the clock IC 12, and at step 104, the soak time is calculated from the elapsed time from the last engine stop to the present. That is, the soak time is calculated from the difference between the current time read in step 103 and the previous time when the engine was stopped last time (SRAM value in step 402 in FIG. 5 above).

Thereafter, in step 105, it is judged whether or not the calculated soak time is longer than a predetermined time a (for example, 6 hours), and if YES, the following step 106
Then, it is determined whether or not the cooling water temperature (sensor detection value) at that time is equal to or higher than a predetermined temperature b (for example, 50 ° C.).

If the cooling water temperature (sensor detection value) has fallen sufficiently when the predetermined soak time has elapsed, it can be judged that the water temperature sensor 25 is normal.
If 6 is NO, it is determined that the water temperature sensor is normal (step 107), and if step 106 is YES, it is determined that the water temperature sensor is faulty (step 108). In addition,
In step 108, a diagnostic code or the like indicating a failure of the water temperature sensor is stored in the EEPROM 15, and a warning lamp (MIL or the like) is turned on to warn the occurrence of the failure.

Next, the reset determination process of the timepiece IC 12 (subroutine of step 101 in FIG. 2 above) will be described with reference to the flowcharts of FIGS. 3 and 4. In the following, the grounds that the reset determination of the clock IC 12 is possible and the procedure of the same processing will be described in order for each of FIGS. 3 and 4.

First, FIG. 3 will be described. in short,
As described above, the sub power supply is supplied to the timepiece IC 12 and the SRAM 13. If the sub power supply drops to a predetermined low voltage range, the operation of the timepiece IC 12 is hindered and the S
Data cannot be properly stored and held in the RAM 13. Specifically, as shown in FIG. 6, the reset voltage (minimum operating voltage) of the timepiece IC12 is about 2.0 V, and when the sub power supply voltage becomes equal to or lower than the reset voltage, the timepiece IC12 is
Is reset. Further, the data holding voltage of the SRAM 13 is about 2.5V, and when the voltage of the sub power supply becomes equal to or lower than the data holding voltage, the data of the SRAM 13 may be destroyed.

In such a case, although the function of monitoring the reset of the clock IC 12 is not originally provided, the SRAM 13 has a power supply monitoring function and can record the history when the sub power supply voltage becomes equal to or lower than the data holding voltage. Therefore, the clock IC12
Is relatively close to the data holding voltage of the SRAM 13, and "reset voltage <data holding voltage", the history that the sub power supply voltage becomes equal to or lower than the data holding voltage by using the power supply monitoring function of the SRAM 13 is If it is confirmed, it is highly likely that the clock IC 12 has been reset.

For example, in FIG. 6, when the sub power supply voltage drops as indicated by the circled numbers 1 or 2 in the figure, the data holding voltage (2.5 V) is dropped in either case, so the history of the sub power supply drop is shown. It remains in the SRAM 13. This indirectly determines the power supply voltage drop for the timepiece IC12 by monitoring the data holding voltage. However, the reset of the timepiece IC12 can be determined without omission because of the magnitude relation between the above voltage values.

In practice, when the microcomputer 14 starts the process shown in FIG. 3, in step 201, it is determined from the history stored in the SRAM 13 whether or not the sub power supply voltage has dropped while the microcomputer is stopped (the engine is stopped). Then, if the sub power supply has not dropped, the process proceeds to step 202, stores the fact that the clock IC is not reset, and then returns to the original process of FIG. If the sub power supply has dropped, the SRAM 13 is initialized in step 203, and further, in step 204, the fact that the clock IC is reset is stored, and then the process returns to the original process of FIG.

On the other hand, the reset judgment processing of FIG. 4 judges the reset of the clock IC 12 by checking the data stored in the SRAM 13 when the microcomputer is started. Specifically, a so-called "keyword check" for determining whether or not a predetermined keyword stored in the SRAM 13 in advance is correct, a "mirror check" for checking the stored data of the SRAM 13 with a true value, and the like are performed. . In this case, if the above check result is abnormal,
Since it can be predicted that the data has been destroyed due to the drop in the sub power supply voltage, it can be determined that the clock IC 12 may have been reset.

Actually, when the microcomputer 14 starts FIG. 4, in step 301, a keyword check is performed, and in step 302, a mirror check is performed. If both steps 301 and 302 are normal (OK), the process proceeds to step 303, stores the fact that the clock IC is not reset, and returns to the original process of FIG. Also, step 3
If any of 01 and 302 is abnormal (NG), the SRAM 13 is initialized in step 304, and further step 30
After the fact that the clock IC has been reset is stored in 5, the process returns to the original process of FIG.

According to this embodiment described in detail above, the following effects can be obtained. Since it is determined whether or not the clock IC 12 has been reset when the microcomputer 14 is started up, the clock IC 12 is activated while the engine is stopped (during the microcomputer stop period).
Even if the 12 reset occurs, it can be recognized immediately after the microcomputer is started.

Since the power supply state to the timepiece IC12 is indirectly monitored from the history indicating that the sub-power supply voltage has dropped to the data holding voltage or less, it is possible to preferably determine whether or not the timepiece IC12 is reset. In this case, SRAM1
The device 3 itself or the microcomputer 14 has a voltage monitoring function which uses the data holding voltage as a threshold value in advance, and by using the existing configuration thereof, the present device can be realized without adding a new configuration.

Further, by checking the data held in the SRAM 13, the power supply state to the timepiece IC 12 is indirectly monitored, so that whether the timepiece IC 12 is reset or not can be suitably judged.

When it is determined that the timepiece IC12 has been reset, the failure determination of the water temperature sensor 25 is prohibited, so that the use of incorrect time data of the timepiece IC12 causes an inconvenience in that the determination result is not appropriate. Therefore, highly reliable sensor failure determination can be performed.

The present invention can be embodied in the following modes other than the above. In the above-described embodiment, the reset determination of the clock IC 12 is performed at the time of starting the microcomputer in accordance with the determination of the failure of the water temperature sensor 25. However, in addition to this, for example, periodically during the normal microcomputer operating period (normal engine operating period). Alternatively, the reset determination of the clock IC 12 may be performed. As a result, whether or not the clock IC 12 is reset can be appropriately determined not only during the microcomputer stop period (engine stop period) but also in other cases. As a result, it is possible to correctly recognize the careless reset of the clock IC 12.

Power supply voltage of clock IC 12 (sub power supply voltage)
May be provided, and the reset of the timepiece IC 12 may be determined based on the detection result of the power supply voltage. As a result, the power supply state to the timepiece IC 12 can be directly monitored, and the reset determination can be performed accordingly. For example, it is advisable to monitor the power supply voltage drop using the minimum operating voltage of the clock IC 12 or a voltage value slightly higher than the minimum operating voltage as a threshold value.

In the above embodiment, the soak time is measured using the time data of the timepiece IC12 and the failure determination of the water temperature sensor 25 is performed based on the soak time, but the use of the timepiece IC12 is not limited to this. For example, when determining a failure of an in-vehicle device such as various sensors or actuators, the time data of the clock IC 12 is stored in the EEPROM together with the failure information (diag code or the like). As a result, the failure occurrence time is stored and the time series of the failure occurrence becomes clear. In such a case, the problem that the time data is distorted due to the reset of the clock IC 12 and the failure analysis is hindered later due to not being noticed is solved.

[0040]

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of a vehicle-mounted control device according to an embodiment of the invention.

FIG. 2 is a flowchart showing a failure determination routine of the water temperature sensor.

FIG. 3 is a flowchart showing a reset determination process of the clock IC.

FIG. 4 is a flowchart showing a reset determination process of the clock IC.

FIG. 5 is a flowchart showing interrupt processing every 1 second.

FIG. 6 is a time chart for explaining the operation of the embodiment.

[Explanation of symbols]

10 ... ECU, 11 ... Power supply IC, 12 ... Clock IC (timekeeping section), 13 ... SRAM, 14 ... Microcomputer (control section), 2
1 ... Battery, 22 ... IG switch (power switch),
25 ... Water temperature sensor.

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields investigated (Int.Cl. ⁷ , DB name) G05B 23/00-23/02 F02D 41/00-41/40

Claims (6)

(57) [Claims] 1. An electronic control unit for engine control mounted on a vehicle for controlling an engine, which operates when an ignition switch is turned on to perform data calculation and control relating to the engine control, and when the ignition switch is turned off. A control unit to be stopped, and the control unit is operated by power supply from a power supply of a different system,
And a time measuring unit for measuring time elapsed during the engine stop, the control unit may be one that performs failure determination of the in-vehicle equipment
In addition, it also determines whether or not the timer has been reset by indirectly or directly monitoring the power supply status to the timer.
If it is determined that the timekeeping unit has been reset,
Is an electronic control unit for engine control , wherein the failure determination is not performed . 2. The electronic control device for engine control according to claim 1, wherein the control unit determines, when the control unit is started, whether or not the time counting unit is reset during a stop period of the control unit. 3. A power supply is provided with the same power supply as that of the timekeeping unit and holding stored contents by power supply from the power supply, with the data holding voltage of the memory somewhat higher than the reset voltage of the timekeeping unit as a threshold value. Engine to monitor the voltage drop
3. An electronic control device for electronic control, wherein the control unit determines whether or not the timer unit is reset based on a history indicating that the power supply voltage of the memory has dropped below the data holding voltage. Engine described in
Electronic control unit for control. 4. A memory having the same power source as that of the timekeeping unit and holding stored contents by power supply from the power source, the control unit checking data held in the memory,
The engine control electronic control unit according to claim 1, wherein it is determined whether or not the timekeeping unit is reset based on the check result. 5. a means for detecting a power supply voltage of the timing section, wherein the control unit ene according to the reset of the timer unit in claim 1 or 2 determines based on the detection result of the supply voltage
Electronic control device for gin control . Further comprising: a coolant temperature sensor for detecting the temperature of coolant of the engine, an electronic for determining engine control fault and a detection value of the water temperature sensor of the water temperature sensor during the elapsed time while the engine is stopped and the engine start It is a control device, The said control part is an electronic control device for engine control in any one of Claims 1-5 which prohibits failure determination of a water temperature sensor, when it determines with the timekeeping part having been reset.