JPS6183973A - Self-diagnostic apparatus of engine control apparatus for motor car - Google Patents

Abstract

PURPOSE:To attain the cost reduction of the titled apparatus, by performing self- diagnosis by forcibly turning the control output to control machinery ON and OFF. CONSTITUTION:The output signal of an output circuit B, of which the output level changes between at the time when the control output issued to control machineries A1-A4 at the time of self-diagnosis is constant and at the time when said control output changes by 1, is inputted to the single self-diagnostic input port of a control apparatus C. The control output to the control machineries A1-A4 is temporarily prohibited by a self-diagnostic output oscillation means D to emit a self-diagnostic control signal having an ON-state and an OFF-state to one control machinery selected according to a predetermined order and, from the level change of the signal inputted through the output circuit B, a diagnostic means E diagnoses whether the control output is normal. Therefore, because a signal can be inputted to the apparatus C by using a single signal circuit, miniaturization is attained. The control output is forcibly turned ON and OFF in spite of the control characteristics of the control machineries A1-A4, the diagnosis of the output signal of the control machinery can be performed by same diagnostic sequence and cost reduction can be attained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a self-diagnosis device for an automobile engine control device.

<Prior art> In automobile engines equipped with electronically controlled fuel injection devices, there is a system that diagnoses the presence or absence of abnormalities in control outputs issued to various control devices from a control device composed of a microcomputer. FIG. 5 shows such a conventional example.

A control output is issued from the microcomputer 3 to a plurality of control devices 1a to 1d such as TA type fuel injection valves through power transistors 21 to 2d, respectively, and each control device 11 to
The operation of 1d is controlled. Then, the control output to each control device 11 to 1d is sent to each signal line 4 & to 4.
d to the input port of the microcomputer 3, and based on these input signals, it is possible to diagnose whether or not there is an abnormality in the shaft output. Specifically, if the control output from the microcomputer 3 is both ON and OFF within a predetermined time after the power is turned on when starting the engine, the control output is diagnosed as normal; ON
Alternatively, if only one of them is OFF, it is diagnosed that there is an abnormality. Note that 5 is a waveform shaping circuit.

<Problems to be Solved by the Invention> However, in such a conventional self-diagnosis device, control outputs to each of the control devices 1a to 1d are input to the microcomputer 3 via the respective signal lines 4& to 4d. As a result, the microcomputer 3 has a plurality of input ports for self-diagnosis and input circuits (waveform shaping circuits) thereto, making the device complex. In addition, since diagnosis is made directly from the control outputs output to each control device 1 & - 14, for example, the control outputs that turn on when the cooling water temperature is 50°C or higher and turn off when the temperature is lower than 50°C can be detected using a microcontroller. When the computer 3 outputs an output signal, the output signal is continuously turned ON during a hot start, so it is not possible to diagnose the OFF state. In addition, since the ON/OFF time of the control output is different for each control device 1a to 1d, the control device 1a
The number of design man-hours required for each diagnostic pattern to match the control characteristics of 1d to 1d was considerable.

In view of the current situation, it is an object of the present invention to provide a self-diagnosis device that solves the above problems while making self-diagnosis possible.

<Structure of the Invention> For this reason, the present invention, as shown in Figure 1, has the following advantages: when all of the control outputs output to the plurality of control devices A1...Person 4 are in a constant state during self-diagnosis, and when one of them is changed. The output signal from output circuit B whose output level changes depending on when the control device C
At the same time, the self-diagnosis output transmitting means temporarily prohibits control output to the control equipment, and outputs the control output to a single control equipment selected in a predetermined order. A control output for self-diagnosis having an ON state and an OFF state is generated, and the diagnostic means E diagnoses whether the control output is normal or abnormal based on the level change of the signal inputted through the output circuit B. This is what I did.

<Example> An example of the present invention will be described below based on the drawings. Incidentally, the same elements as those in the conventional example are given the same reference numerals as in FIG. 1, and the explanation thereof will be omitted.

FIGS. 2 and 3 show an embodiment of the present invention.

In FIG. 2, the collector terminals of power transistors 21L-2d are connected to one ends of capacitors 11a-11d, respectively. The other ends of these capacitors 11 & ~11d are connected to the input terminal of an A/D converter 13 via a single signal line 12, and the output terminal of the A/D converter 13 is connected to a microcontroller as an engine control device. computer 1
Connected to 4 input ports. 15A and 15B are voltage dividing resistors, and 16A and 16B are diodes.

The CPU (not shown) of the microcomputer 14 executes a normal control routine for outputting control outputs to each control device 1a to 1d via power transistors 2& to 2'd, as in the conventional example. . Further, the microcomputer 14 is configured to sequentially select the control devices 1 & - 1d to be diagnosed at predetermined intervals (for example, every minute) and execute the interrupt routine shown in the flowchart of FIG. 3 instead of the normal control routine. Here, a multi-output circuit is constructed with capacitors 11 &~11 dK.

Next, the flowchart shown in FIG. 3 will be explained.

First, to explain the normal control routine, the microcomputer 14 outputs a control output for operation to each control device 11 to 1d, such as a fuel injection valve, via the power transistors 2 and 2d, based on various input signals, Each control device 1
Activate a to 1d.

In such a normal control routine, the microcomputer 14 selects a control device to be diagnosed (for example, 1a) after a predetermined period of time has elapsed, and activates the interrupt routine shown in FIG. That is, all control devices 1a to 1
The control output to d is temporarily stopped, for example, turned off, and after the set time has elapsed, the voltage v1 at the Nakabatake point in Figure 2 is read (Sl
, Sl.

Sa). At this point, power transistors 2&~2d
Since the capacitors lla to 11d are turned off, the capacitors lla to 11d are charged, and the voltage v1 at point a becomes a voltage determined by the voltage dividing ratio of the voltage dividing resistors 15A and 15B.

Thereafter, the control output of the control device 1a to be diagnosed is inverted and forcibly turned ON (S4), and the voltage v2 at point a at this time is read (S5). At this point, when the control output is normal and turned ON, current flows through the power transistor 2& via the ONL capacitor 111L and the power transistor 2a, and the voltage at point a decreases. Then, after inverting the control output and returning the control output to the control device 1a to the state at the start of the interrupt routine (S6), the voltage v1,
The difference IV1-Vzl of v2 is compared and determined (S7). When the difference M/1-Vzl exceeds the set value α, the control output from the microcomputer 14 turns on normally.
, the microcomputer 14 is diagnosed as being normal because it is turned off and the voltage changes.
o On the other hand, when the difference IVI -V21 is less than the set value, the control output from the microcomputer 14 is abnormal, e.g.
Since it is maintained in the N or OFF state, the voltage change at point a is small, and it is diagnosed that the microcomputer 14 is abnormal (89).

This routine is interrupted into the normal control routine at predetermined time intervals and sequentially repeated to diagnose whether or not there is an abnormality in the control outputs of the control devices 1&-1d.

In this way, the control device to be diagnosed is repeatedly selected and the control output to that control device is forcibly reversed to turn it on and off.
FF, and the microcomputer 14 is diagnosed based on the voltage change at point a when they are turned on and off, so self-diagnosis can be performed using a single signal line 12 and a single input port of the microcomputer 14. The self-diagnosis device can be made smaller and its cost can be reduced. Also,
Regardless of the control characteristics of each control device 11 to 1d, the control output is forcibly turned ON/OFF and self-diagnosis is performed based on the voltage change at that time, so multiple control devices 1&... Since the control output to 1d can be diagnosed, the number of design steps can be reduced, which also helps reduce costs. Further, since self-diagnosis is performed by forcibly turning the control signal ON and OFF', self-diagnosis of the control output to the electric cooling fan can also be performed, for example, when the output signal is turned ON continuously after a hot start.

FIG. 4 shows another embodiment of the invention.

In this embodiment, one end of each resistor 17 & 17d is connected to the power transistor 2 & 2dO:r collector terminal, and the other end of each resistor ITa 17d is connected to a single capacitor 18.
It was designed to connect to. Then, the voltage at point b of the capacitor 1B is input to the microcomputer 14 via the A/D converter 13. The microcomputer 14 forcibly turns the control output ON and OFF as in the previous embodiment.
The FF is turned on and the presence or absence of an abnormality is diagnosed from the difference in voltage at point b at those times.

<Effects of the Invention> As explained above, the present invention sequentially selects control outputs to be diagnosed and forcibly turns on the control outputs to the corresponding control equipment.
-Turn it off and self-diagnose.

Therefore, a signal can be inputted to the input terminal of the self-diagnosis device using a single signal line, and the self-diagnosis device can be made smaller and its cost can be reduced. Also,
Since self-diagnosis is performed by forcibly turning the control output ON-OFF regardless of the control characteristics of each control device, it is possible to diagnose the output signals of multiple control devices based on the same diagnostic sequence. can reduce costs.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the present invention, FIG. 2 is a block diagram showing an embodiment of the present invention, and FIG. 3 is a 70-cha diagram of the same. 1a to 1d...control equipment 111 to 11d, 1B.
...Capacitor 12...Signal line 14...
Microcomputer patent applicant, agent of Japan Electronics Co., Ltd.
Patent Attorney Fujio SasashimaFigure 1Figure 2Figure 3Figure 4Figure 5

Claims (1)

[Claims] In a self-diagnosis device for an automobile engine control device that self-diagnoses control outputs issued to a plurality of control devices from a control device constituted by a microcomputer,
At the time of self-diagnosis, an output circuit whose output level changes depending on whether all of the plurality of control outputs are in a constant state and when the control output to be diagnosed is in a state in which the control output is changing is provided, and the output signal of the output circuit is transmitted to a single controller of the control device. A self-diagnosis having an on state and an off state for one control device selected according to a predetermined order by inputting input to one self-diagnosis input port while temporarily prohibiting control output to the control device. and a diagnostic means for diagnosing whether the control output to the control device is normal or abnormal based on the presence or absence of a level change in the signal input to the self-diagnosis input port. A self-diagnosis device for an automobile engine control device, characterized in that: