JPH0932615A - Engine controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suitably compensate engine control when an A/D converter is in its abnormal state by eliminating arrangement such as a backup circuit. SOLUTION: Analog output such as an intake pipe inner pressure sensor 3 and an engine water temperature sensor 4 out of sensors for detecting the operating condition of an engine is converted into a digital value by an A/D converter 63 and put in a microcomputer 60. At that time, in the microcomputer 60, an A/D conversion value is stored in an RAM 603 by SIN(serial input) interruption. While in the microcomputer 60, a controlled variable on the basis of the A/D conversion value is calculated on a base routine, and this controlled variable calculated by NE interruption on the basis of a pulse from a crank angle sensor 1 is outputted to a controlled part driving circuit 64. When the A/D converter 63 is in its abnormal state, in the microcomputer 60, a fail-safe value is outputted to the driving circuit 64 by the NE interruption whose priority order is higher than the SIN interruption.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine control device for electronically controlling an operation related to fuel injection and ignition of an engine, and more particularly to an analog quantity which indicates an operating state of the engine.
The present invention relates to an improvement of a control device configuration for maintaining a proper engine control even when an abnormality occurs in the A / D converter in a control device for converting into a digital amount by a D converter.

[0002]

2. Description of the Related Art Generally, such an engine control device is shown in FIG. 10 between the A / D converter and a microcomputer which calculates an engine control amount based on the converted digital amount. Such serial communication is performed.

That is, (1) In a microcomputer, a timer interrupt is generated at regular time intervals such as 1 ms (milliseconds), so that the A / D converter is designated by A / D channel designation.
The / D conversion request is serially transmitted (SOUT). (2) As a result, in the A / D converter, the specified A
A / D channel (CH1, CH2 ...) analog input
A / D conversion is performed, and the A / D converted value is serially transmitted to the microcomputer (SIN). Such serial communication is performed between the A / D converter and the microcomputer.

Note that these communications are performed in synchronization with the clock output from the microcomputer to the A / D converter. FIG. 11 shows the A / D channel (A / D conversion request) and A / D that are transmitted and received based on the clock.
The serial data transmission structure of the converted value is shown.

Incidentally, these A / D channels and A / D converted values basically have a common data transmission structure,
As shown in FIG. 11B, a START bit (start bit) that becomes a logic L (low) level, a data bit that consists of, for example, 8 bits (bit), and a STOP bit (stop bit) that becomes a logic H (high) level. The serial data to be transmitted is transmitted in synchronization with the clock shown in FIG.

In the microcomputer, when the A / D converted value having such a structure is received, an interrupt request signal as shown in FIG. 11 (c) is generated in the microcomputer, and the SIN (serial in) interrupt is generated. Such processing is executed. The request signal for the SIN interrupt is automatically generated from the internal circuit of the microcomputer 10 or more bits after the START bit is detected. Further, in the SIN interrupt, a process of storing the received A / D conversion value in the RAM is performed.
FIG. 12 shows the processing related to the SIN interrupt, and FIG. 13 shows the processing related to the timer interrupt by the microcomputer, respectively, for reference.

On the other hand, in the microcomputer,
In addition to the processing related to the SIN interrupt or the timer interrupt, as the basic processing, arithmetic processing based on the base routine as shown in FIG. 14 is repeatedly executed.

That is, in the microcomputer, unless the above-mentioned interrupt occurs, the engine speed NE (rp) of the engine follows the base routine shown in FIG.
m), fuel injection amount TAU (μs), ignition timing TESA
(Μs) and so on are repeatedly executed.

Here, the fuel injection amount TAU and the ignition timing T
The control amount of the ESA or the like is calculated on the basis of the rotational speed NE calculated each time, and the values of the engine water temperature and the intake pipe internal pressure which are A / D converted through the A / D converter. .

The calculated control amount is output based on a so-called NE interrupt generated by an input pulse from the crank angle sensor. FIG. 15 shows an output mode of each control amount based on such an NE interrupt.
The processing procedures involved in this NE interrupt are shown in FIG.

That is, the NE interrupt is shown in FIG.
It is activated based on the generation of an interrupt request signal inside the microcomputer at the falling edge of the input pulse from the crank angle sensor shown in FIG. And
In the interrupt routine, first, step S1 in FIG.
As the processing of 601, the time T180 (μs) between 180 ° CA (crank angle) is calculated from the difference between the previous NE interrupt generation time and the current NE interrupt generation time. Incidentally, the calculation of the engine speed NE (rpm) in the base routine (FIG. 14) is performed at the calculated time T1.
It is performed based on 80 (μs).

When the time T180 (μs) is calculated in this way, next, as the processing of step S1602 in FIG.
In the mode shown in FIG. 15B, the output process of the fuel injection pulse to the injector is executed. FIG. 17 shows a specific procedure for this fuel injection pulse output processing.

That is, when outputting the fuel injection pulse, first, in step S1701, the injector is turned on.
It is turned on, and in the next step S1702, the fuel injection amount TAU calculated in the above base routine (FIG. 14).
The value of (μs) is written to timer A. Thereby, in the microcomputer, as shown in FIG. 15B, the injector is automatically turned off after the elapse of the time TAU (μs). Note that such timer control is automatically executed through the internal circuit of the microcomputer.

In the NE interrupt, when the output process of the fuel injection pulse is completed in this way, next, step S in FIG.
As the processing of 1603, the processing of outputting the ignition timing pulse to the igniter is executed in the mode shown in FIG. FIG. 18 shows a specific procedure of this ignition timing pulse output processing.

That is, when outputting the ignition timing pulse, first, in step S1801, the igniter ON time TIGON (μs) shown in FIG. 15C is calculated. This is calculated as, for example, TIGON = T180 / 3 (μs). Then, in step S1802, from the time T180 (μs) previously calculated, the time TIGON (μs) calculated this time and the ignition timing TESA (μs) calculated in the above base routine (FIG. 14).
Time minus (T180-TIGON-TESA)
Is written in the timer B, and the igniter ON time TIGON (μs) is written in the timer C in step S1803. As a result, in the microcomputer, as shown in FIG. 15C, after the time (T180-TIGON-TESA) written in the timer B has elapsed, the igniter is automatically turned ON and further written in the timer C. After the lapse of time TIGON, the igniter is automatically turned off. These timer controls are also automatically executed through the internal circuit of the microcomputer.

As described above, in such an engine control device, the fuel injection amount TAU of the engine and the ignition timing T
The amount of control such as ESA can be converted to A / D through the A / D converter.
It is calculated based on the converted engine water temperature and intake pipe pressure. Therefore, if some abnormality occurs in the A / D converter, there is a disadvantage that the above-described engine control cannot be normally maintained.

Therefore, in the prior art, for example, Japanese Patent Laid-Open No. 3-23331.
An engine control method has been proposed in which, when the A / D converter is abnormal, as in the device described in Japanese Patent Laid-Open No. 60, the control amounts are calculated using preset fixed values instead of the A / D converted values. There is.

[0018]

When the A / D converter is in an abnormal state, the control method for calculating the controlled variables with the preset fixed values as described above causes an abnormal state based on the abnormal A / D converted value. It seems as if normal engine control is maintained without calculating the control amount.

However, in general, the priority of the interrupt to the microcomputer (or its base routine) is the highest for the NE interrupt related to the output processing of various control amounts, and the SIN related to the acquisition of the A / D conversion value.
Interrupts are relatively low. The priorities of the interrupts in the engine control device described above are shown in FIG. 19 for reference.

As described above, in such an engine control system, the engine speed NE (rpm), fuel injection amount TAU (μs), ignition timing TESA ( μs), etc. are repeatedly performed. (B) Issue an A / D conversion request (A / D channel) to the A / D converter by a timer interrupt (FIG. 13). (C) The A / D conversion value received by the SIN interrupt (FIG. 12) is stored in the RAM. (D) The NE interrupt (FIG. 16) outputs the fuel injection pulse and the ignition timing pulse. The contents are controlled.

The output timing of the fuel injection pulse and the ignition timing pulse with respect to the input from the crank angle sensor is very important. Especially, the ignition timing pulse causes knocking unless it is output at accurate timing. . For this reason, normally, as shown in FIG. 19, the NE interrupt for outputting these pulses has the highest priority.

On the other hand, the received A / D conversion value is converted to R
The SIN interrupt stored in the AM is usually given a low priority as shown in FIG. 19 because there are not so many timing restrictions as described above for engine control.

On the other hand, the fuel injection amount TAU and the ignition timing TES
Since the control amount of A and the like requires a relatively long processing time, for example, many calculations are executed based on the A / D converted values related to the engine water temperature, the intake pipe pressure, etc., and various corrections are required.
Usually, it is calculated by the base routine as described above.

According to such a background, when the conventional A / D converter is abnormal, the control amount is calculated using a preset fixed value instead of the A / D converted value. The control method such as, for example, A / D from the same A / D converter
The communication line (SIN) for serially inputting the D conversion value is GND
In the case of (ground) short circuit, the following inconveniences would occur.

That is, this serial input communication line is GN
When the D is short-circuited, the microcomputer always detects the START bit that is at the logical L level, and as a result, the above-mentioned SIN interrupt based on the internal interrupt request signal shown in FIG. . As a result, the above base routine does not rotate at all, and the fuel injection amount TAU and ignition timing TES
The calculation of the control amount such as A is not performed either. This situation is the same even when the fixed value is used instead of the A / D converted value.

At this time, the NE interrupt, which has a higher priority than the SIN interrupt, secures the processing related to the output of the fuel injection pulse and the ignition timing pulse, and the fuel injection amount T immediately before such an abnormality occurs.
These fuel injection pulse and ignition timing pulse are output based on AU, ignition timing TESA, and the like.

Therefore, immediately before the occurrence of this abnormality, for example, the ignition timing TESA is "advanced" or the fuel injection amount TAU is in the air-fuel ratio "lean" depending on the operating state of the engine. If you do,
Good engine control is not performed, it may stall,
It may also cause knocking.

Further, in the microcomputer whose operation is monitored by the reset circuit (watchdog circuit), the processing of the base routine is stopped in this way, whereby the watchdog clear (WDC) signal to the reset circuit is sent. Output is also stopped. After all, in such a microcomputer, the reset continues to be applied, and the outputs of the fuel injection pulse and the ignition timing pulse are completely stopped.

Incidentally, if a backup circuit is additionally provided like the other device described in the above publication and the engine control is compensated by this backup circuit when the A / D converter is abnormal, such inconvenience will certainly occur. Will be avoided. However, in this case, the space and cost inconveniences caused by separately providing the backup circuit cannot be ignored.

The present invention has been made in view of the above circumstances, and an engine control device capable of suitably compensating the engine control when the A / D converter is in an abnormal state without providing a backup circuit or the like. The purpose is to provide.

[0031]

In order to achieve such an object, in the invention described in claim 1, the operating condition detecting means for detecting the operating condition of the engine and the analog output of the operating condition detecting means are converted into digital values. A / D converter
Control amount calculation means for calculating the engine control amount by fetching the A / D converted value by the A / D converter based on the conversion completion interrupt, and the calculation based on the interrupt having a higher priority than the conversion completion interrupt. As an engine control device for controlling the operation of an engine, the A / D is provided with a control amount output means for outputting an engine control amount, and a drive means for driving an engine controlled part according to the output control amount. The control amount output means includes an abnormality detecting means for detecting an abnormality of the converter, and the control amount output means uses the abnormality detecting means.
When a converter abnormality is detected, a predetermined fail-safe value that replaces the calculated engine control amount is output to the drive means.

Further, in the invention of claim 2, in the configuration of the invention of claim 1, the abnormality detecting means detects an abnormality of the A / D converter in which at least the conversion completion state is maintained. Is to be detected.

According to a third aspect of the invention, in the configuration of the second aspect of the invention, the control amount computing means is:
When it is assumed that a watchdog clear signal is repeatedly generated and is output to a watchdog circuit in accordance with repeated calculation of the engine control amount based on loop processing, the engine control device is configured to operate by the abnormality detection means. Means for forcibly outputting the watchdog clear signal to the watchdog circuit based on a periodic interrupt having a higher priority than the conversion completion interrupt when an abnormality in which the conversion completion state of the A / D converter is sustained is detected. Is further provided.

According to the invention of claim 4, in the structure of the invention of claim 1, 2 or 3, the number of revolutions detecting means for detecting the number of revolutions of the engine and the number of revolutions detected are detected. Fail-safe value changing means for changing the fail-safe value.

According to the fifth aspect of the invention, the operating state detecting means for detecting the operating state of the engine and the A / A for converting the analog output of the operating state detecting means into a digital value.
A D converter, control amount calculation means for calculating an engine control amount by fetching an A / D conversion value by the A / D converter based on the conversion completion interrupt, and an interrupt having a higher priority than the conversion completion interrupt. As an engine control device for controlling the operation of the engine, which has a control amount output means for outputting the calculated engine control amount based on the above, and a drive means for driving the engine controlled part according to the output control amount. The control amount calculation means prohibits the conversion completion interrupt when the abnormality detecting means detects an abnormality in the A / D converter. A predetermined fail-safe value in place of the engine control amount to be calculated is given to the control amount output means.

Further, in the invention of claim 6, in the configuration of the invention of claim 5, the abnormality detecting means detects an abnormality of the A / D converter in which at least the conversion completion state is maintained. Is to be detected.

Further, in the invention according to claim 7, in the structure of the invention according to claim 5 or 6, the rotational speed detecting means for detecting the rotational speed of the engine, and the rotational speed detecting means according to the detected rotational speed. The configuration further comprises fail-safe value changing means for changing the fail-safe value.

According to the invention of claim 8, in the configuration of the invention according to any one of claims 1 to 7, there is provided information indicating that an abnormality of the A / D converter is detected by the abnormality detecting means. The memory to be stored and this A / D
The configuration further includes an alarm unit that executes appropriate alarm processing based on the presence of information indicating that the converter is abnormal.

[0039]

As an engine control device, the invention according to the above-mentioned claim 1 is provided with: abnormality detecting means for detecting abnormality of the A / D converter, and the control amount output means uses the abnormality detecting means for A / D conversion. When a malfunction of the vessel is detected, a predetermined fail-safe value that replaces the calculated engine control amount is output to the drive means. With such a configuration, in the event of any abnormality in the A / D converter, the fail-safe value is output to the drive means based on the interrupt with the high priority.

That is, no matter what the engine operating condition is just before the A / D converter becomes abnormal, after the A / D converter has failed, the stall is caused based on the fail-safe value. Proper engine control without causing knocking or knocking will be maintained.

In the invention according to claim 2, the abnormality detecting means detects an abnormality of the A / D converter in which at least the conversion completion state is maintained. With such a configuration, conversion completion interrupts (SIN interrupts) of the A / D converter occur frequently due to, for example, the GND short circuit of the serial input line described above, and the calculation of the engine control amount itself by the control amount calculation means is stopped. Even in such a case, such a situation can be accurately detected. Even in this case, since the output of the fail-safe value based on the interrupt with the high priority described above is ensured, the appropriate engine control based on the fail-safe value is appropriately maintained.

Further, in this case, according to the invention of claim 3, the control amount calculation means repeatedly generates a watchdog clear signal in accordance with the repeated calculation of the engine control amount based on the loop processing, and outputs the watchdog clear signal. Output to the circuit. When the abnormality detecting means detects an abnormality in which the conversion completion state of the A / D converter is maintained, the engine control device performs the watchdog based on a periodic interrupt having a higher priority than the conversion completion interrupt. It further comprises means for forcibly outputting a clear signal to the watchdog circuit. With such a configuration, even when the operation as the control device is monitored by the watchdog circuit, and due to the abnormality of the A / D converter, the calculation of the engine control amount itself by the control amount calculation means is stopped. In this case, the operation of the control device itself will not be reset by the watchdog circuit.

Therefore, also in this case, the output of the fail-safe value based on the interrupt with the higher priority is secured, and the proper engine control based on the fail-safe value can be preferably maintained.

On the other hand, according to the fourth aspect of the present invention, it comprises: a rotation speed detecting means for detecting the rotation speed of the engine. A fail safe value changing means for changing the fail safe value according to the detected rotation speed. By adopting such a configuration, it becomes possible to make the engine control based on the fail-safe value more appropriate when the A / D converter is abnormal.

Further, the engine control device of the invention according to claim 5 is provided with: abnormality detecting means for detecting an abnormality of the A / D converter, and the control amount calculating means is When an abnormality of the / D converter is detected, the conversion completion interrupt is prohibited, and a predetermined fail-safe value in place of the engine control amount to be calculated is given to the control amount output means. With such a configuration, when the A / D converter is in an abnormal state, the fail safe value is surely given to the control amount output means, and the drive means drives the engine controlled portion according to the given fail safe value. Come to do.

That is, in this case, since the conversion completion interrupt is prohibited when the A / D converter is abnormal, even if the control amount calculating means calculates the engine control amount by a loop process, the process is executed. It will not be stopped. At this time, the same control amount calculation means
Since the processing for giving the fail-sale value to the control amount output means is performed without depending on the / D conversion value, proper engine control without causing abnormal behavior can be maintained in this case as well.

At this time, the control amount calculating means directly outputs the fail-sale value to the control amount output means without calculating the control amount with a preset fixed value as in the example shown as the conventional control method. By giving it, the memory space required for those operations can be saved.

Further, in the invention according to the above-mentioned claim 6 on the premise of such a configuration, the abnormality detecting means detects the abnormality of the A / D converter in which at least the conversion completion state is maintained. According to the above configuration, in this case as well, due to the GND short circuit of the serial input line or the like, normally, A /
It becomes possible to accurately detect the situation where the conversion completion interrupt (SIN interrupt) of the D converter frequently occurs. Moreover, in this case, as described above, the interrupt is immediately prohibited by the control amount calculation means, and thereafter, the fail-sale value is given to the control amount output means through the control amount calculation means. Proper engine control based on .alpha.

On the other hand, in these configurations, as in the invention according to claim 7, it comprises: a rotation speed detecting means for detecting the rotation speed of the engine. A fail safe value changing means for changing the fail safe value according to the detected rotation speed. If such a configuration is adopted, in this case as well, engine control based on the fail-safe value when the A / D converter is abnormal becomes more appropriate.

Further, in any of the above constructions,
According to the invention described above, a memory is provided for storing information indicating that an abnormality of the A / D converter is detected by the abnormality detecting means. An alarm means is provided for executing appropriate alarm processing based on the presence of information indicating that the A / D converter is abnormal in the memory. If such a configuration is further adopted, the fact that the abnormality of the A / D converter is detected can be surely notified to the driver or the dealer.

That is, it becomes possible to favorably support the judgment as to whether the vehicle should normally run afterwards or whether to run in the escape mode through the alarm processing.

The alarm processing based on the abnormality information stored in the memory includes, for example, lighting of a warning lamp, sounding of a buzzer, or warning or error display of the same at the time of diagnosis processing at a dealer or the like.

[0053]

1 shows an embodiment of an engine control device according to the present invention. The engine control device of this embodiment is
When electronically controlling the operation related to fuel injection or ignition of the engine, the control is appropriately maintained even when an abnormality occurs in the A / D converter that converts the analog amount indicating the operating state of the engine into a digital amount. It is configured as a device that can.

First, with reference to FIG. 1, the structure of the apparatus of the embodiment will be described. As shown in FIG. 1, the apparatus according to the embodiment is mainly composed of sensor groups 1 to 5 for detecting an operating state of an engine (not shown) to be controlled, an electronic control unit 6, and this electronic control unit 6. It has a warning lamp 7 and a group of actuators 8 to 9 whose drive is controlled by.

Of these, the sensor group is
It is classified into one that outputs a digital quantity and one that outputs an analog quantity. That is, whether or not the crank angle sensor 1 which is arranged on the crankshaft of the engine and outputs a pulse corresponding to the rotation thereof as shown in FIG. 15A and the transmission of the vehicle are in the neutral position. The neutral detection switch 2 or the like for detecting whether or not is classified as a device that outputs a digital amount. On the other hand, the intake pipe internal pressure sensor 3 for detecting the pressure in the intake pipe of the engine, the engine water temperature sensor 4 for detecting the cooling water temperature of the engine, and the intake air temperature sensor 5 for detecting the engine intake air temperature are assumed to output analog quantities. being classified.

The electronic control unit 6 includes the microcomputer 60 and the digital interface 6
1, analog interface 62, A / D converter 6
3, a drive circuit 64 and a reset circuit (watchdog circuit) 65 are basically included in the engine control device of the embodiment.

In this electronic control unit 6, the sensor group 1
5 to 5 while performing the predetermined calculation according to the contents of these signals, lighting the warning lamp 7 arranged on the instrument panel or the like of the vehicle and the injector which is the controlled part of the engine. 8 and igniter 9 are controlled.

Here, the outputs of the crank angle sensor 1 and the neutral detection switch 2 which are classified as those which output the digital amount are input to the digital interface 61 of the electronic control unit 6, where "0" or It is converted into a binary voltage signal of "5" V and taken into the microcomputer 60.

On the other hand, the outputs of the intake pipe internal pressure sensor 3, the engine water temperature sensor 4, the intake air temperature sensor 5, etc., which are classified as those which output the analog amount, are input to the analog interface 62 of the electronic control unit 6, After noise removal or the like is performed here, each A / D converter 63
Input to D channel.

Between the A / D converter 63 and the microcomputer 60, serial communication as shown in FIGS. 10 and 11 is performed. That is, SOUT synchronized with the clock from the microcomputer 60
The A / D converter 63 is activated by specifying the A / D channel as
The converted value is received by the microcomputer 60 as SIN which is also synchronized with the clock. Further, by receiving the A / D converted value by the microcomputer 60 in this way, in the microcomputer 60, an interrupt request signal as shown in FIG. 11C is generated in the microcomputer 60, and the SIN interrupt is generated. Processing will start.

As shown in FIG. 1, the microcomputer 60 itself includes the CPU 601 and the CPU
A ROM 602 in which a control program executed by 601 and control data are pre-registered, a RAM 603 in which a calculated value at the time of the control, the A / D conversion value, and the like are temporarily stored,
This is a well-known device configured to have a backup RAM 604 which is a non-volatile data memory backed up by a battery, a timer 605 used for timer control, and the like.

As its operation, basically, the fuel injection pulse width and the ignition timing pulse width are calculated according to the outputs of the sensor groups 1 to 5 based on the control program.
The calculated fuel injection pulse width and ignition timing pulse width are generated as the output of the timer 605. As a result, the drive circuit 64 drives the injector 8 with the calculated fuel injection pulse width and drives the igniter 9 with the calculated ignition timing pulse width.

On the other hand, the operation of the microcomputer 60 is monitored through the reset circuit (watchdog circuit) 65 and outputs a WDC (watchdog clear) signal to the reset circuit 65 when the control program is executed. (Repeat the WDC signal repeatedly)
As a result, the fact that the device is operating normally is transmitted to the reset circuit 65. That is, when the control program does not operate normally and the output (inversion) of the WDC signal is stopped, the reset circuit 65 resets the microcomputer 60.

Further, in the apparatus of the present embodiment, the microcomputer 60 constantly monitors the presence / absence of an abnormality in the A / D converter 63, and when an abnormality is detected in the A / D converter 63, the abnormality is detected. A flag to that effect is set in the RAM 603 or the backup RAM 604, the warning lamp 7 is driven to light, and the compensation process for engine control described below is executed.

2 to 7, including the abnormality detection processing of the A / D converter 63 by the microcomputer 60,
The control procedure relating to the engine control and the compensation processing procedure are shown. Next, the engine control operation of the apparatus of the embodiment will be described in further detail with reference to FIGS.

First, a method of detecting an abnormality of the A / D converter 63 including an abnormality of the communication line will be described. This abnormality detection is performed by the microcomputer 6 shown in FIG.
This is performed through the processing related to the timer interrupt of 0 and the processing related to the SIN interrupt of the microcomputer 60 shown in FIG. As described above, the timer interrupt is an interrupt that is periodically generated, for example, every 1 ms (millisecond), and the SIN interrupt is 10 or more when the START bit (see FIG. 11) of the A / D conversion value is detected. This is an interrupt that occurs after a bit.

In FIG. 2 and FIG. 3, the counter CADCER is a counter for detecting a failure of the A / D converter 63 itself or an abnormality such as a disconnection of its communication line. When judged, the flag XADCER is set (= 1). On the other hand, the counter CADCERS is abnormal such that the communication line with the A / D converter 63 is GND shorted, that is, as described above.
This is a counter for detecting an abnormality in which the SIN interrupts occur frequently, and when it is determined that such an abnormality has occurred, the flag XADCERS is set (= 1). Note that these flags XADCER and XADCER
S is the RAM 603 or the backup RAM 60
Set to 4. When set in the backup RAM 604, the contents of these flags are retained even after the power supply to the electronic control unit 6 is stopped. In either case, when an abnormality is detected and a vehicle is diagnosed by a dealer or the like, appropriate alarm processing (for example, error display) is performed based on the flag contents. And in the apparatus of the embodiment, these flags XADCER and XADCERS are stored in the RAM 6
03 or the backup RAM 604, the warning lamp 7 is controlled to be turned on, and the driver or the like is warned that an abnormality has occurred in the A / D converter 63.

Upon detection of this abnormality, the microcomputer 60 executes the following processes in the timer interrupt shown in FIG. 2 and the SIN interrupt shown in FIG.

Whenever a timer interrupt occurs, the microcomputer 60 first sets the count value of the counter CADCER to the maximum value ("25" in step S201).
5 ”), and if the maximum value has not been reached, the count value of the counter CADCER is incremented in the next step S202. The count value of the counter CADCER is reset to "0" by the SIN interrupt (step S303 in FIG. 3).

In the microcomputer 60, in step S203 of the timer interrupt, when the count value of the counter CADCER is CADCER> 10, that is, when the SIN interrupt is not applied during 10 ms, the A / D Assuming that the converter 63 itself is out of order or its communication line is broken, the flag XADCER is set in step S204. On the other hand, when the count value of the counter CADCER is CADCER ≦ 10, the flag XADC of the flag is determined in step S205.
ER is cleared (= 0), and the process proceeds to the next step S206.

In step S206, the count value of the other counter CADCERS is checked. The counter CADCERS is a counter whose count value is incremented by the SIN interrupt shown in FIG. That is, the maximum value (“2
55 "), and if the maximum value is not reached, the same count value is incremented in the next step S302.

Therefore, in the check in step S206, it is possible to see the interrupt frequency depending on how many counts the above-mentioned counter CADCERS has, that is, how many SIN interrupts are taken in 1 ms. And here, the counter CAD
When the count value of CERS is CADCERS> 10, that is, when the SIN exceeds 10 times in 1 ms.
When interrupts occur, the SIN interrupts occur frequently, that is, the communication line with the A / D converter 63 is GN.
Assuming that there is a D short circuit, the flag XADCERS is set in step S207. On the other hand, when the count value of the counter CADCERS is CADCERS ≦ 10, the same flag XADC is determined in step S208.
ERS is cleared (= 0), and the next step S209 is performed.
Then, the count value of the counter CADCERS is reset to "0".

In this way, the microcomputer 60 which has completed the abnormality detection of the A / D converter 63 calculates the A / D channel in the timer interrupt (FIG. 2) as in the conventional case (step S210), and calculates the calculated A / D channel. A / D on D channel
The data is transmitted to the converter 63 (step S211). Also SI
As a result of the N interrupt (FIG. 3), this A / D converter 6
The A / D conversion value returned from No. 3 is stored in the RAM (A / D storage RAM) 603 (step S304).

Next, the processing of the WDC (watch dog clear) signal executed by the microcomputer 60 of the apparatus of this embodiment through the timer interrupt shown in FIG. 2 will be described.

The counter CWDC shown in FIGS. 2 and 4 is used for processing the WDC signal. This counter CWDC is incremented through the timer interrupt, and the base routine shown in FIG. 4 (step S
The counter is reset to "0" by 404).

That is, in the microcomputer 60,
At the time of the timer interruption, the counter CWD is set in the next step S212 after the transmission of the A / D channel is completed.
It is checked whether or not the count value of C is the maximum value (“255”), and if it has not reached the maximum value, it is incremented in the next step S213.

In the microcomputer 60, the communication line to the A / D converter 63 is set to G in step S214.
The flag XADCER indicating that the ND is shorted
The state of S is checked, and if it is set (= 1), the WDC signal is forcibly output to the reset circuit 65 (the logical level thereof is forcibly inverted) in step S216. As a result, in an abnormal state where at least the communication line with the A / D converter 63 is GND short-circuited, the WDC signal is output from the microcomputer 60 to the reset circuit 65 at every 1 ms of the timer interrupt. Become so. That is, during that time, the operation of the microcomputer 60 is not reset. This is to ensure that the compensation processing based on the NE interrupt, which will be described later, is secured even if the SIN interrupts occur frequently due to the GND short circuit and the base routine shown in FIG. 4 does not normally rotate.

On the other hand, if the flag XADCERS is not set in the check in step S214, the microcomputer 60 proceeds to the next step S2.
At 15, the count value of the counter CWDC is checked. When this is CWDC> 50, that is, even if it exceeds 50 ms, the counter C
When the count value of WDC is not reset by the base routine, the microcomputer 60 determines the WD.
The output of the C signal (logic level inversion) is stopped. On the other hand, if the count value of the counter CWDC is CWDC ≦ 50, the WDC signal is normally output (logical level inversion) in step S216. That is, when the count value of the counter CWDC is reset by the base routine within 50 ms, normally (every 1 ms).
When the WDC signal continues to be output and the count value is not reset even after 50 ms, the output of the WDC signal is stopped and the reset circuit 65 resets the microcomputer 60. FIG. 5 shows the relationship between the WDC signal and the reset timing by the reset circuit 65.

As shown in FIGS. 5A and 5B, in the reset circuit 65, the logic level inversion of the WDC signal is stopped, and there is no logic level inversion for 40 ms after the last inversion. 10ms immediately after
The microcomputer 60 is reset only during the period.
Then, after that, the reset circuit 65 continues to monitor the logic level of the WDC signal, and thereafter, the WDC signal is further monitored for 40 ms.
If there is no logic level inversion in the DC signal, the microcomputer 60 is reset again for 10 ms immediately after that. These operations are repeatedly executed.

As described above, in the microcomputer 60, the output of the fuel injection pulse and the ignition timing pulse is completely stopped when the reset is continued in this way. Therefore, in the apparatus of the embodiment, as described above, when the flag XADCERS indicating that the communication line with the A / D converter 63 is GND shorted is set, this WDC signal is forcibly output through the timer interrupt. I am trying to do it. As a result, even if the base routine does not rotate normally, the following compensation processing based on the NE interrupt is ensured.

Next, the fuel injection control and the ignition timing control by the apparatus of the embodiment executed based on the NE interrupt, including the compensation processing when the abnormality of the A / D converter 63 is detected, will be described. To do.

In the apparatus of the embodiment, the microcomputer 60 calculates the engine speed NE (step S401) and the fuel injection amount TAU according to the base routine shown in FIG. 4 unless an interrupt occurs (step S401). In step S402, the ignition timing TESA is calculated (step S403), and the counter CWDC is reset (step S404).

Here, the control amounts of the fuel injection amount TAU, the ignition timing TESA, etc. are calculated by A / D converter 63 through the A / D converter 63 as well as the rotational speed NE calculated each time.
It is calculated based on the output of the intake pipe pressure sensor 3 and the output of the engine water temperature sensor 4 which are converted, and the calculated control amount is determined by the input pulse from the crank angle sensor 1 shown in FIG. Based on the NE interrupt that occurs, the output is performed in the mode shown in FIG. 15, and the like are the same as those of the conventional device.

In such an engine control device, when the A / D converter 63 is abnormal, the control amount is calculated by a preset fixed value instead of the A / D converted value. When the communication line with the A / D converter 63 is GND short-circuited: The base routine cannot be executed at all due to the frequent occurrence of SIN interrupts. However, the NE interrupt having a higher priority than the SIN interrupt secures the processing related to the output of the fuel injection pulse and the ignition timing pulse. The processing related to this output is performed based on the fuel injection amount TAU, the ignition timing TESA, etc. immediately before the occurrence of this abnormality. Therefore, immediately before the occurrence of the abnormality, for example, the ignition timing TESA is "advanced" or the fuel injection amount TAU is in an air-fuel ratio "lean" state depending on the operating state of the engine. In this case, good engine control may not be performed, resulting in stall or knocking. As described above, such inconvenience may occur.

Therefore, in the apparatus of the present embodiment, the time T180 (FIG.
5 (a) and step S1601 in FIG. 16) are calculated, the fuel injection pulse is output according to the routine shown in FIG. 6, and the ignition timing pulse is output according to the routine shown in FIG.

First, the output processing of the fuel injection pulse shown in FIG. 6 will be described. When outputting this fuel injection pulse, first, in step S601, the injector is turned on.
After being turned on, the next steps S602 and S603 are performed.
Then, it is checked whether or not the flags XADCER and XADCERS are set. And the same flag XAD
If either CER or XADCERS is set, compensation is performed by the fail-safe value in step S604. That is, here, the timer A
The fail-safe value (μs) is written in. This fail-safe value is selected as a value that does not stall (stalling) even in the idle state and that allows retreat traveling as a value that replaces the fuel injection amount TAU (μs) calculated in the base routine (FIG. 4). .

On the other hand, steps S602 and S603 described above.
In the check of, the above flags XADCER and XA
When it is determined that all DCERS have been cleared, the fuel injection amount TAU (μs) calculated in the above base routine is written in the timer A in step S605 as in the conventional case.

By writing the fuel injection amount TAU calculated by the fail safe value or the base routine in the timer A in this way, the microcomputer 60 automatically operates the injector 8 after the time written in the timer A has elapsed. The control to turn it off is automatically executed.

Next, the output process of the ignition timing pulse shown in FIG. 7 will be described. At the time of outputting this ignition timing pulse, first, in step S701, FIG.
Igniter ON (on) time TIGON (μ
s) is calculated. This is also calculated as, for example, TIGON = T180 / 3 (μs). Then, next, in steps S702 and S703, the flags XADCER and XADCE are set.
Whether or not RS is set is checked, and these flags XA
If either DCER or XADCERS is set, compensation by the fail-safe value is performed in step S704. That is, here, the time (T180-TIGON-failsafe value) obtained by subtracting the time TIGON (μs) and the failsafe value (μs) calculated this time from the previously calculated time T180 (μs) is written in the timer B. Be done. This fail-safe value is selected as a value that does not cause knocking and is capable of retreat travel as a value that replaces the ignition timing TESA (μs) calculated in the base routine (FIG. 4).

On the other hand, steps S702 and S703 described above.
In the check of, the above flags XADCER and XA
When it is determined that all DCERS have been cleared, in step S705, the time TI calculated this time is calculated from the time T180 (μs) previously calculated as in the conventional case.
GON (μs) and time (T180) obtained by subtracting the ignition timing TESA (μs) calculated in the above base routine.
-TIGON-TESA) is written to timer B.

Thus, the time (T180-TIGON-fail safe value) or (T180-TIGON-T
After ESA) is written to timer B, step S7
At 06, the above calculated igniter ON time TIGO
N (μs) is written to timer C.

As a result, in the microcomputer 60, the igniter 9 is turned on after the time written in the timer B has passed, and the igniter 9 is turned off after the time TIGON written in the timer C has passed.
The control to turn it off is automatically executed.

According to the apparatus of the same embodiment, A /
In case of any abnormality of the D converter 63, the fail-safe value is output to the drive circuit 64 based on the NE interrupt having a higher priority than the SIN interrupt.

Therefore, no matter what the engine operating state is just before the A / D converter 63 becomes abnormal, after the abnormality of the A / D converter 63 occurs, based on the same fail safe value, Proper engine control is maintained without stalls or knocking.

Further, according to the apparatus of the embodiment, even when the operation of the microcomputer 60 is monitored by the reset circuit (watchdog circuit) 65, it is caused by the GND short circuit of the communication line with the A / D converter 63. When the base routine is stopped, the operation related to the NE interrupt is properly secured without resetting the operation of the microcomputer 60.

In the apparatus of the embodiment, fixed values that do not cause stall or knock are selected as the fail-safe values corresponding to the fuel injection amount TAU and the ignition timing TESA. However, this may be changed according to the time T180 calculated corresponding to the number of revolutions at each time by the NE interruption. With such a configuration, it becomes possible to make the engine control based on the fail-safe value more appropriate when the A / D converter is abnormal.

Further, in the apparatus of the same embodiment, the A / D converter 6
When abnormality 3 is detected, flags XADCER and X indicating that
ADCERS to RAM603 or backup RAM
By setting to 604, the compensation process based on such a fail-safe value is performed, and the warning lamp 7 is turned on to warn the driver or the like. However, in addition to this, as shown by the broken line in FIG.
It is also possible to adopt a configuration in which this is reset when abnormality 3 is detected. If this abnormality is due to an operation abnormality of the A / D converter 63 itself, such reset may restore it to normal.

By the way, some microcomputers have a function of inhibiting each of the above interrupts by the control program thereof. For example, the SIN
When the base routine does not rotate due to frequent interrupts, the SIN interrupt is not entered even if the interrupt request signal of the SIN interrupt is generated. This is typically done by writing a "1" or "0" as a control flag to a particular register.

FIGS. 8 to 9 show another embodiment of the engine control device according to the present invention, assuming that a microcomputer of this type is used as the microcomputer 60.

That is, in the other embodiment, as shown in FIGS. 8 and 9, when the SIN interrupt is frequently generated, the SIN interrupt is prohibited and the fail safe values are set in the base routine. Try to set it. Less than,
The details will be described with reference to FIGS. 8 and 9.

First, the timer interrupt routine shown in FIG. 8 will be described. Also in this embodiment, the timer interrupt shown in FIG. 8 and the S shown in FIG.
Through the IN interrupt, the abnormality of the A / D converter 63
It also detects the abnormality of the communication line.

This timer interrupt is, for example, 1 ms.
It must be an interrupt that occurs periodically every (millisecond),
Further, in FIG. 8, a counter CADCER is a counter for detecting a failure of the A / D converter 63 itself or an abnormality such as a disconnection of its communication line.
The RS is a counter for detecting an abnormality such as a GND short-circuit of the communication line with the A / D converter 63, that is, an abnormality such that the SIN interrupt occurs frequently, as in the case of the previous embodiment. When these abnormalities are detected, the corresponding flags XADCER or XADCER
S is the RAM 603 or the backup RAM 604
Will be set to. It is the same as in the previous embodiment that appropriate alarm processing is performed in the dealer or the like based on the set flags XADCER or XADCERS, and that the warning lamp 7 is controlled to light.

In the timer interrupt shown in FIG. 8, the microcomputer first executes step S8.
In 01, it is checked whether or not the count value of the counter CADCER is the maximum value (“255”). If the count value has not reached the maximum value, the count value of the counter CADCER is determined in the next step S802. Increment.
The count value of the counter CADCER is reset to "0" by the SIN interrupt (step S303 in FIG. 3).

Then, in the microcomputer, at step S803 of the timer interruption, the counter CA
When the count value of DCER is CADCER> 10, that is, when no SIN interrupt occurs during 10 ms, during that period, it is determined that the A / D converter 63 itself has a failure or its communication line is broken, step S804. Then, the flag XADCER is set. On the other hand, when the count value of the counter CADCER is CADCER ≦ 10, the same flag XADC is determined in step S805.
ER is cleared (= 0), and the process proceeds to the next step S806.

In step S806, the count value of the other counter CADCERS is checked. It was also described above that the counter CADCERS is a counter whose count value is incremented by the SIN interrupt shown in FIG. And here again, the same counter CADC
When the count value of ERS is CADCERS> 10, that is, when the SIN exceeds 10 times in 1 ms.
When interrupts occur, the SIN interrupts occur frequently, that is, the communication line with the A / D converter 63 is GN.
Assuming that there is a D short circuit, the flag XADCERS is set in step S807. In this case, in this embodiment, in step S809, the subsequent S
Disable IN interrupt. On the other hand, the same counter CADCE
When the count value of RS is CADCERS ≦ 10, in step S808, the flag X
Without returning the ADCERS, the counter C
Reset the count value of ADCERS. This is because once the SIN interrupt is disabled in step S809,
The counter CADCERS is no longer incremented, and the abnormality detection process returns, that is, the flag XAD.
This is because it is impossible to return (clear) the CERS itself. Therefore, in the case of the embodiment, the flag XADCE
Rather than setting RS in backup RAM 604,
It is desirable to set it in the RAM 603 and to reset (clear) the flag XADCERS when the key switch is switched from OFF to ON.

The microcomputer which has completed the abnormality detection of the A / D converter 63 in this way calculates the A / D channel (step S810) as in the conventional or previous embodiments.
The calculated A / D channel is transmitted to the A / D converter 63 (step S811).

However, in the case of the present embodiment, the base routine shown in FIG. 9 continues to rotate due to the prohibition of the SIN interrupt, so that the processing of the next WDC (watch dog clear) signal is different from that of the previous embodiment. It will be different.

That is, the counter CWDC is used for the processing of this WDC signal, and its count value is incremented through a timer interrupt, as in the previous embodiment. However, in the case of this embodiment, the flag XADCERS is set. Even if the abnormality occurs, the reset operation of the counter CWDC is maintained as long as the base routine shown in FIG. 9 continues to rotate. Therefore, the process of step S214 shown in FIG. 2 is unnecessary, and only the processes of steps S814 and S815 corresponding to the processes of steps S215 and S216 of FIG. 2 are performed. That is, in step S814, the count value of the counter CWDC is checked.
When the count value of WDC is not reset by the base routine, output of the WDC signal (logical level inversion) is stopped. On the other hand, if the count value of the counter CWDC is CWDC ≦ 50, the output (logical level inversion) of the WDC signal is maintained in step S815.

Next, the processing in the base routine of the embodiment shown in FIG. 9 including the compensation processing when the abnormality of the A / D converter 63 is detected will be described. In the apparatus of the embodiment, the microcomputer repeatedly executes the set processes according to the base routine shown in FIG. 9 unless an interrupt occurs.

That is, when executing this base routine, first, at step S901, the engine speed NE is set.
Is calculated, the presence or absence of the setting of the flags XADCER and XADCERS is checked in the next steps S902 and S903. Then, the same flag XADC
If either ER or XADCERS is set, compensation is performed by the fail-safe value in steps S904 and S905. That is, here, the fuel injection TA to be calculated in the same base routine.
Each fail-sale value in place of U (μs) and ignition timing TESA (μs) is substituted as these values TAU and TESA. In this case as well, as the fail-safe value assigned to the fuel injection TAU, a value that does not stall (stalling) even in the idle state and is capable of retreat traveling is selected, and the fail-safe value assigned to the ignition timing TESA is selected. As a result, a value that does not cause knocking and is capable of retreat traveling is selected.

On the other hand, steps S902 and S903 described above.
In the check of, the above flags XADCER and XA
When it is determined that all DCERS are cleared, the fuel injection amount TAU is calculated in step S906, and the ignition timing TESA is calculated in step S907. The calculated fuel injection amount TAU, the ignition timing TESA, and other control amounts are A / D converted through the A / D converter 63, including the rotational speed NE calculated each time. As described above, it is calculated based on the output of the engine water temperature sensor 4 and the output of the engine water temperature sensor 4.

In this way, the microcomputer which has completed the calculation of the control amounts TAU and TESA or the substitution of the fail-safe value resets the counter CWDC in step S908, and then executes the above-mentioned step S901.
Return to processing. In the case of the embodiment, the calculated control amounts TAU and TESA or the control amounts TAU and TESA in which the fail-safe value is substituted are based on the NE interrupt shown in FIG.
In the procedure shown in FIG. 7 and FIG. 18, it is output to the drive circuit 64.

As described above, the engine control apparatus shown in FIG. 1 also performs the timer interrupt as shown in FIG. 8 and executes the base routine as shown in FIG. 9 by the A / D converter. When 63 is abnormal, the fail-safe value is surely given to the output routine, and the injector 8 and the igniter 9 are driven in accordance with the given fail-safe value.

Therefore, even with the configuration of the embodiment, the stall may occur after the abnormality of the A / D converter 63 occurs regardless of the engine operating state immediately before the abnormality of the A / D converter 63. Therefore, proper engine control without causing knocking can be maintained.

In the apparatus of the embodiment, in the base routine shown in FIG. 9, when the A / D converter is abnormal, the above-described fixed value is used instead of the A / D converted value. The control amounts TAU and TESA may be calculated. However, in this case, the ROM 60
2 and the RAM 603 also require an extra memory space for the calculation. In general, if the vehicle runs only in the evacuation mode, the fixed value as described above is sufficient as the fail-safe value.
It can be said that this configuration is effective in saving the memory space required for those calculations. However, the fail-safe value can be changed in accordance with the rotation speed NE calculated each time, as in the case of the previous embodiment.

Further, even in the apparatus of the same embodiment, the A / D
When an abnormality of the converter 63 is detected, this may be reset. As described above, if this abnormality is caused by the operation abnormality of the A / D converter 63 itself, the reset may restore the normal operation.

Also in the apparatus of this embodiment, the flag XADCER or XADCER is the same as in the previous embodiment.
When S is set, the warning lamp 7 is turned on to alert the driver or the like that the A / D converter 63 is abnormal. However, instead of this, or in addition to this,
Needless to say, the configuration may be such that a buzzer sounds or an error is displayed on the display panel or the like. In short, what is necessary is just to have a means that can notify the driver of the above-mentioned abnormality.

[0118]

As described above, according to the present invention, there is no need to provide a backup circuit, etc.
Suitable compensation for engine control when the D converter is abnormal,
You will be able to maintain.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an engine control device according to the present invention.

FIG. 2 is a flowchart showing a timer interrupt processing procedure of the embodiment.

FIG. 3 is a flowchart showing a SIN interrupt processing procedure of the embodiment.

FIG. 4 is a flowchart showing a base routine processing procedure of the embodiment.

FIG. 5 is a time chart showing reset timing by a reset circuit.

FIG. 6 is a flowchart showing a fuel injection pulse output procedure of the embodiment.

FIG. 7 is a flowchart showing an ignition timing pulse output procedure of the embodiment.

FIG. 8 is a flowchart showing a timer interrupt processing procedure of another embodiment.

FIG. 9 is a flowchart showing a base routine processing procedure of another embodiment.

FIG. 10 is a block diagram showing a serial communication mode of A / D converted values.

FIG. 11 is a time chart mainly showing the data structure of the serial communication data.

FIG. 12 is a flowchart showing a conventional general SIN interrupt processing procedure.

FIG. 13 is a flowchart showing a conventional general timer interrupt processing procedure.

FIG. 14 is a flowchart showing a conventional general base routine processing procedure.

FIG. 15 is a time chart showing a control amount output mode based on an NE interrupt.

FIG. 16 is a flowchart showing a conventional general NE interrupt processing procedure.

FIG. 17 is a flowchart showing a conventional general fuel injection pulse output procedure.

FIG. 18 is a flowchart showing a conventional general ignition timing pulse output procedure.

FIG. 19 is a schematic diagram showing the general priority of various interrupts.

[Explanation of symbols]

1 ... Crank angle sensor, 2 ... Neutral detection switch, 3 ... Intake pipe pressure sensor, 4 ... Engine water temperature sensor, 5 ... Intake temperature sensor, 6 ... Electronic control unit, 7 ... Warning lamp, 8 ... Injector, 9 ... Igniter, 60 ... Microcomputer, 61 ... Digital interface, 62 ... Analog interface, 63 ... A / D converter, 64 ... Drive circuit, 65 ... Reset circuit (watchdog circuit), 601 ... CPU, 602 ... ROM, 60
3 ... RAM, 604 ... Backup RAM, 605 ... Timer.

Claims (8)

[Claims] 1. An operating state detecting means for detecting an operating state of an engine, an A / D converter for converting an analog output of the operating state detecting means into a digital value, and an A / D conversion by the A / D converter. Control amount calculation means for calculating the engine control amount by taking in a value based on the conversion completion interrupt; and control amount output means for outputting the calculated engine control amount based on an interrupt having a higher priority than the conversion completion interrupt. An abnormality detection for detecting an abnormality of the A / D converter, the engine control apparatus having a driving unit for driving an engine controlled unit according to the output control amount to control the operation of the engine. The control amount output means includes an A /
An engine control device, which outputs a predetermined fail-safe value in place of the calculated engine control amount to the drive means when an abnormality of the D converter is detected. 2. The engine control device according to claim 1, wherein the abnormality detecting means detects an abnormality of the A / D converter in which at least the conversion completion state is maintained. 3. The engine control device according to claim 2, wherein the control amount calculation means repeatedly generates a watchdog clear signal in accordance with a repeated calculation of the engine control amount based on a loop process, and outputs this to a watchdog circuit. When the abnormality detecting unit detects an abnormality in which the conversion completion state of the A / D converter is maintained, the engine control device has a higher priority cycle than the conversion completion interrupt. The engine control device further comprising means for forcibly outputting the watchdog clear signal to the watchdog circuit based on an interrupt. 4. The engine control device according to claim 1, 2 or 3, wherein a rotation speed detecting means for detecting the rotation speed of the engine and a fail-safe value for changing the fail-safe value according to the detected rotation speed. An engine control device further comprising safe value changing means. 5. An operating state detecting means for detecting an operating state of the engine, an A / D converter for converting an analog output of the operating state detecting means into a digital value, and an A / D conversion by the A / D converter. Control amount calculation means for calculating the engine control amount by taking in a value based on the conversion completion interrupt; and control amount output means for outputting the calculated engine control amount based on an interrupt having a higher priority than the conversion completion interrupt. An abnormality detection for detecting an abnormality of the A / D converter, the engine control apparatus having a driving unit for driving an engine controlled unit according to the output control amount to control the operation of the engine. Means for controlling the amount of control by the abnormality detecting means.
An engine control device, wherein when an abnormality of the D converter is detected, the conversion completion interrupt is prohibited and a predetermined fail-safe value in place of the engine control amount to be calculated is given to the control amount output means. 6. The engine control device according to claim 5, wherein the abnormality detecting means detects an abnormality of the A / D converter in which at least the conversion completion state is maintained. 7. The engine control device according to claim 5, wherein a rotation speed detecting means for detecting the rotation speed of the engine, and a fail safe value for changing the fail safe value according to the detected rotation speed. An engine control device further comprising a changing unit. 8. The engine control device according to claim 1, wherein the abnormality detection unit stores information indicating that an abnormality of the A / D converter is detected, and the memory is stored in the memory. An engine control device further comprising alarm means for executing appropriate alarm processing based on the presence of information indicating that the A / D converter is abnormal.