JPH02165069A - Abnormality detector for electric circuit - Google Patents

Abstract

PURPOSE:To detect abnormality in electric circuits by using a transformer which is provided on a power source base line with a detection gain adjustable freely by the number of turns as current detection sensor to detect circuit currents of different levels with one sensor accurately. CONSTITUTION:Currents of different levels flowing through electric circuits connected to a power source base line 25 are detected as voltage accurately for each of the electric circuits according to a timing at which a load is controlled with a computer by means of a current detection sensor 22 made up of a transformer 26a with a detection gain adjustable freely by the number of turns, a Hall element 27 and the like. Then, abnormality in the electric circuits is judged by comparing the results of the detection with a reference voltage for each of the circuits.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electric circuit abnormality detection device for detecting abnormalities in a plurality of electric circuits connected to an electronic control device mounted on a vehicle or the like.

[Prior art and problems to be solved by the invention] Generally,
BACKGROUND ART A plurality of electric circuits whose loads include actuators and the like are connected to an electronic control device mounted on a vehicle such as an automobile, and these electric circuits are driven by, for example, control signals from the electronic control device. It is equipped with a function to diagnose whether or not the above-mentioned electric circuits are operating normally in response to control signals. A current sensor is provided, and this current sensor detects the current value of the power supply bus, and a detection circuit compares the detection signal of the current sensor with the control signal at that time, and the control item is in a normal operating state. A technique is disclosed for detecting that there is.

However, in the preceding example, when the control signals for multiple electric circuits overlap in time, the current value of the power supply bus bar that is the sum of the load currents of each electric circuit is detected, and when an abnormality is detected, A control signal is output from the control circuit to each electric circuit individually.

Thereafter, the system in which the abnormality has occurred is determined by ORing the individual control 911 signals and the current sensor.

Therefore, the detection circuit requires a number of abnormal system discrimination circuits corresponding to the number of electric circuits, and a large number of external circuits must be added to the control circuit. Therefore, not only does this result in an increase in cost, but also an increase in the installation space due to an increase in the number of circuit mounting boards, and a decrease in reliability due to an increase in the number of connector pins for connection with the control circuit.

Furthermore, when detecting the load currents for all loads with one current sensor installed on the power supply bus, the magnitude of the current value differs depending on the load in each electric circuit, so the detection level for each is different, and the current Detection accuracy varies depending on the load. Therefore, there is a problem in that it is difficult to determine an abnormality with a degree of certainty regardless of the load on the electric circuit.

[Object of the Invention] The present invention has been made in view of the above circumstances, and it detects circuit currents of different levels in each of a plurality of electric circuits using one current detection sensor, and determines the state of the electric circuit based on this circuit current. An object of the present invention is to provide an abnormality detection device for an electric circuit that can reliably detect abnormalities.

[Means for Solving the Problems 1] An electric circuit abnormality detection device according to the present invention detects abnormalities in a plurality of electric circuits when the plurality of electric circuits are controlled by control signals. A current detection sensor is installed on the power supply bus of an electric circuit, and includes a plurality of transformers whose detection gain according to the load of each electric circuit can be adjusted by the number of windings, and the current detection sensor is calculated based on the output of the current detection sensor. It also includes a circuit state determining means that compares the current value with a preset reference current value and determines whether the electric circuit is normal or not.

[Function] Due to the above-mentioned Makisei, the detection gain of the transformer of the current detection sensor is adjusted by the number of windings according to the load of the electric circuit, and the current of the power supply bus that varies depending on the load of the electric circuit is detected. be done.

The current value extracted based on the output of the current detection sensor is compared with a reference current value set in advance by the circuit state determining means, and it is determined whether the electric circuit is normal or not.

[Embodiments of the invention] Hereinafter, the present invention will be described in detail with reference to the drawings.

1 to 5 show a first embodiment of the present invention, FIG. 1 is a functional block diagram of an abnormality detection device for an electric circuit according to the present invention, FIG. 2 is a circuit block diagram, and FIG. ) is an explanatory diagram showing the current detection sensor, Fig. 3(b) is a characteristic diagram of the current detection sensor, and Fig. 4 shows the control signal and current detection sensor output I3.
5(a) and 5(b) are flowcharts showing the procedure for checking the operation of the electric circuit.

(Circuit structure) In Fig. 2, reference numeral 1 is an electronic control unit (ECU) consisting of a microcomputer, etc., which is installed in vehicles such as automobiles and performs various controls such as engine control, transmission control, and air conditioner control. I do.

The above ECUI connects the computer unit 2 with resistors 3 and 4.
．． Transistors 6.7.8 and the like are connected through the respective transistors 5 to drive electrical loads such as various actuators. For example, the transistor 6 includes a current limiting resistor 9.
, an injector 10 are connected to the transistor 7, and an idle speed control valve (ISC) is connected to the transistor 7.
V) 11 is connected. Further, a current limiting resistor 12 and an ignition coil 13 are connected to the transistor 8 provided outside the ECU 1.

The computer unit 2 has, for example, intake air a
Control sensors 14 such as a sensor, a crank angle sensor, and an 02 sensor are connected, and various data are picked up from the control sensors 14 according to an internally stored control program, and various control data are processed. .

The computer unit 2 deduces various control data based on the data from the control sensors 14, and controls the actuators 10 at a predetermined timing.
, 11, 13, etc. as a control signal. As a result, various controls such as air-fuel ratio control, idle speed control, and ignition timing control are performed.

On the other hand, reference numeral 15 is a diagnostic unit, in which a microprocessor (CPIJ) 16, ROM 17, RAM 18, non-volatile RAM 18a, output interface 19, and input interface 20 are connected to each other via a path line 21. A generator 12S16a is connected to the CPU 16 and supplied with a reference clock. This reference clock is counted by a free-running counter either as it is or after being frequency-divided, and by reading the value of the free-running counter, the reference time of each timing can be determined.

A self-diagnostic lamp 21 is connected to the output interface 19 to notify abnormalities in the control system, and the input interface 20 is connected to the ECU 1 and control sensors 14, as well as a current detection sensor 22 and a battery. 23 are connected via an analog-to-digital converter (A/D converter) 24.

In addition, a power source 81 line 25 extending from the battery 23
is connected via the current detection sensor 22 to the current limiting resistor 9 to the injector 10 to the transistor 6, l5CV1.
1 to transistor 7 and current limiting resistor 12 to ignition coil 13 to transistor 8 to form an electric circuit, and a current supplied from the battery 23 to each electric circuit is provided in the power supply bus 25. The current is directly detected by the current detection sensor 22.

As shown in FIG. 3(a), the current detection sensor 22 has an annular core 26 made of, for example, ferrite.
A transformer 26a wound with electric wire branching from the power supply bus 25 to each electric circuit is formed corresponding to each electric circuit, and a part of the annular core 26 is opened and a Hall element 27 is installed in the opening. The amplifier 28 is connected to the Hall element 27, and the entire structure is molded with resin, for example.

When a control signal is output from the power bus 25 to each electric circuit and a current flows, a magnetic field is generated by this current, and the magnetic flux passing through the core 26 of the transformer 26a is transferred to the Hall cord 27.
A voltage is generated in the Hall element 27 through the hole. The voltage generated in the Hall element 27 is amplified and output by the amplifier 28, and a voltage approximately proportional to the current is output. When the control signals output to each electric circuit are narrow in time, the output of the Hall element 27 has a value added to the output of the transformer 26a.

The transformer 26a is configured such that its detection gain can be adjusted by the number of windings of the transformer 26a in accordance with the load of each electric circuit, and the detection level of the current that varies depending on the load of each electric circuit is adjusted. It can be adjusted, and it is possible to ensure the detection accuracy over a wide current range in response to various electrical loads.

Furthermore, depending on the load to be diagnosed, the transformer 2
By increasing the number of windings of 6a, the amplifier 28
It is possible to omit this and reduce costs.

As shown in FIG. 3(b), the characteristics of the current detection sensor 22 are such that the current I, which is an input signal, and the output voltage V have a substantially linear relationship. An unbalanced voltage due to electrical variations in the output appears as an offset voltage VO when there is no input signal.

On the other hand, the ROM 17 stores a diagnostic program and backup data in the event of a failure, and the RAM 18 stores the current detection sensor 22 which has been converted into a digital signal by the A/D converter 24. The output of the battery 23, various control signals performed by the ECU 1, and various data from the control sensors 14 are temporarily stored.

Further, the non-volatile RAM 18a stores trouble data in case a failure occurs in the actuators 10, 11, 13, the control sensors 14, or the control system, and is backed up by the battery 23 (not shown). The stored trouble data is retained even when the key switch is OFF.

The CPU 16 diagnoses various data stored in the RAM 18 according to the diagnostic program stored in the ROM 17, and when an abnormality is found, it lights up (blinks) the self-diagnosis lamp 21 to notify the driver of the abnormality. Trouble data indicating the content is stored in the nonvolatile RAM 18a.

That is, the current detection sensor 22 detects the current supplied from the power bus 25 to each electric circuit,
Abnormalities in the actuators 10, 11, 13, etc. in each electric circuit are detected from this current value. moreover,
If a failure occurs in the control sensors 14 and data exceeding the output within the normal usage range is input, the R
The backup data stored in OMl7 is transferred to the above EC.
If an abnormality occurs in the ECUI itself, it switches to simple control and sends fixed control data to back up the ECU 1.

That is, the diagnosis unit 15 detects that the ECU
1. Comprehensive failure diagnosis can be performed not only for the control sensors 14 but also for the actuators 10, 11. Only one current detection sensor 22, which was previously installed for each electric circuit, is required, and since it is provided within the diagnostic unit 15, reliability such as vibration resistance and water resistance is improved.

(Functional Configuration) Next, the functional configuration of the diagnostic unit 15 will be described.

The diagnostic unit 15, as shown in FIG.
OM17. RAM18. (consisting of a non-volatile RAM 18a), circuit current value locking means 33, and circuit state determining means 34
, and an output processing means 35.

The input processing means 30 includes the ECU 1, control sensors 14, battery 23, and current detection sensor 22.
The output signal is directly or subjected to waveform shaping and analog-to-digital conversion processing, and is stored in the storage means 32.

The diagnostic means 31 diagnoses various data taken in through the input processing means 30 according to the diagnostic program stored in the storage means 32, and when an abnormality is detected, the trouble data is stored in the storage means 32 (specifically, the nonvolatile RAM 18a).

In the circuit state determining means 33, the current detection sensor 2
From the output of step 2, the circuit current value of the electric circuit to be diagnosed is determined and calculated. That is, the current detection sensor 22
Since the detection gain is adjusted according to the load of each electric circuit and the current is detected, the electric currents of electric circuits of different sizes can be detected uniformly and with good viscosity. In order to accurately calculate the circuit current value of the electric circuit to be diagnosed from the output of the current detection sensor 22, it is necessary to use a control signal outputted from the ECU 1 to the electric circuit to be diagnosed and control signals to other electric circuits. The circuit current value of the electric circuit to be diagnosed may be calculated by determining the output state of the signal and reading the output of the current detection sensor 22 after a predetermined period of time has elapsed since the start of output of the control signal.

Here, as described above, the offset voltage VO exists in the current sensor 22, and this offset voltage VO is not always constant, but fluctuates due to the influence of drift due to temperature changes, changes over time, etc., and also due to individual differences. There are variations due to Therefore, in order to calculate the circuit current of the electric circuit to be diagnosed, an offset current value corresponding to the offset voltage VO of the current detection sensor 22 is read and stored in the storage means 32 (5J, RAM 18 in the body). At the same time, the offset current value is subtracted from the current value corresponding to the output value detected by the current detection sensor 22 after a predetermined period of time has elapsed since the control signal of the electric circuit to be diagnosed was turned on.

For example, taking the above injector 10 as an example, after the pulsed jii3 P t is turned ON, the current value I corresponding to the output voltage v1 of the current detection sensor 22 T1 after a certain period of time has elapsed.
From LTl, the offset current value I LTO corresponding to the offset voltage VO of the current detection sensor 22 at TO when the control signal output to the injector 10 is ON is reduced to obtain the actual circuit current value rL (1l-
ILTI - rLTo ) is determined and this is repeated for each pulse.

In the case of an inductance load such as the injector 10, the rise of the current is delayed with respect to the control signal voltage (pulse signal Pi), as shown in the 1inj-c 1 current waveform in FIG. Sometimes, the offset current value I of the current detection sensor 22 may be read, but in resistive loads, capacitive loads, lamp loads, etc., there is no phase d of the current with respect to the signal voltage, and the control signal voltage is turned on at the same time. As the current rises, the control signal voltage becomes O
The offset current value ILTO of the current detection sensor 22 may be read immediately before the current detection sensor 22 is turned on.

Furthermore, when detecting the offset current value ILTO, if a control signal is being output to another electric circuit as shown in FIG. 4, the offset current value f1 of the electric circuit to be diagnosed. The circuit current values of TO and other electric circuits end up being overlapping values. Therefore, before the control signal to the electric circuit to be diagnosed is turned on and when no control signal is output to other electric circuits, the offset current value ILTO of the current detection sensor 1-22 is detected. .

For example, when the drive pulse signal Pi for the injector 1o is output, it is determined whether the control signal output from the ECIJ 1 overlaps with the electric circuit to be diagnosed and other electric circuits. , and when the control signal for the electric circuit to be diagnosed does not overlap in time with the control signal for other electric circuits, from the output no.j of the current detection sensor 22 when the pulse signal P is ONL, The above offset current value I LTO is newly detected, and this new offset current value (LTO is used to detect the above RA
The offset current value ILTO stored at a predetermined address of M18 is updated. On the other hand, when the control signal is output from the ECUI to another electric circuit, the R
Without updating the offset current value I LTO stored at a predetermined address of AM18, the above-mentioned circuit current value It
When calculating the offset current value 11. stored at a predetermined address in the RAM 18, the offset current value 11. Use TO as is.

The circuit state determination means 34 compares the circuit current value of the electric circuit calculated by the circuit current value calculation means 33 with the reference current WilR stored in the storage means 32 to determine whether the electric circuit is normal. It is determined whether or not it is, and outputted to the diagnostic means 31.

The reference current value IR is, for example, the voltage B of the battery 23.
A reference current value IR preset from the characteristics of each electric load in the electric circuit is stored as a table in the storage means 32 (specifically, the ROM 3) with (2) as a parameter, and the pulse to the injector 10 is stored as a table. Signal P
When i is output, the reference current value IR is determined using the battery voltage BV at that time as a parameter either directly from the above table or by supplementary [111 calculation]. With respect to this base Q'4 current value IR, the circuit current value IL has a preset allowable range Δ■1? By determining whether or not the electric circuit is within the range, it is possible to determine whether or not the state of the electric circuit is normal. and,
When the circuit state determining means 34 determines that the state of the electric circuit is abnormal, the diagnostic means 31 stores trouble data indicating the electric circuit and the details of the abnormality in the storage means 32 (specifically, the non-volatile RAM 18a).

In the output processing means 35, the circuit state determination means 34
When an abnormality is detected, an abnormality signal is output from the diagnostic means 31 and the self-diagnosis lamp 21 is turned on (flashing).
, to notify of an abnormality in the electric circuit.

Incidentally, the trouble data stored in the storage means 32 is stored when the vehicle is parked at a service station (dealer).
It can be read by connecting an external device, such as a width axis diagnostic device, to the ECU1, thereby making it possible to easily identify the abnormality target.

(Operation) Next, the procedure for checking the operation of the electric circuit with the above configuration will be explained in the fifth section.
This will be explained according to the flowcharts in FIGS. (a) and (b).

Although the injector 10 will be explained here as an example of the electric load, the same applies to other electric loads such as the 15CV11 and the ignition coil 13.

When the control signal for starting injection to the injector 10, that is, the drive pulse signal shown by Pi in FIG. 4, is output, the interrupt program shown in FIG. 5(a) is started,
In step 5101, a trigger signal for starting Δ/D conversion is output to the A/D converter 24 from the rise of the drive pulse signal Pj at time TO, and the A/D converter 24 outputs the trigger signal for starting the Δ/D conversion to the current detection sensor +J22. Digital conversion of the output voltage signal begins.

Next, the process proceeds to step 5102, where the output state of the υ1111 signal from the ECU1 to each electric circuit is read via the input interface 20, and the process proceeds to step 5103. In step 5103, it is determined whether or not the control signal is being output to other electric circuits, and if it is determined that the control signal is not being output to other electric circuits, step 510
On the other hand, if it is determined that the control signal is being output to another electric circuit, the process advances to step 5105.

When it is determined in step 5103 that the control 2D signal is not output to other electric circuits, step 5104
Now, the offset current value I LTO corresponding to the offset voltage ■0 of the current detection sensor 22 at time To converted into a digital signal by the A/D converter 24 is stored at a predetermined address in the RAM 18 in the previous routine. Update the stored offset current value +140.

Next, in step 5105, the A/D converter 24 is
/D conversion end signal is output, and an A/D conversion start time is set so that A/D conversion is started again after a predetermined time T1 has elapsed from the rise of the drive pulse signal Pi output to the injector 10. End the interrupt routine.

For example, in a load having an inductance such as the injector 10, the predetermined time T1 is
As shown by 1nj, the current value differs depending on the elapsed time from when the control signal becomes ON1 until reaching the steady current (h), so it is set appropriately according to the characteristics of the load.

Next, when the predetermined time T1 has elapsed, the first interrupt program shown in FIG.
Conversion is started, and in step 5202, the A/D converter 24 converts the current value corresponding to the output voltage of the current detection sensor 22 at the 'i time T1 shown in FIG. I LTI and the A/D converter 24
The voltage BV of the battery 23 converted into a digital signal at
are respectively stored at different addresses in the RAM 18.

Next, when proceeding to step 5203, the above step 510
4"C stored offset current value ILTO and the above 5
The current value ILTI stored in step 202 is stored in the RAM1 above.
8 and the circuit current value IL (IL=ILTI
-ILTO) is calculated, and the process advances to step 5204.

In step 5204, for example, RO
The above injector 10 from the table stored in M17
Find the reference current value IR directly or by interpolation calculation,
A diagnostic value I DIAG is calculated from this reference current value JR and the circuit current value 11 calculated in step 3203 above (
(DIAG=IL-1111) LT, step 52
Proceed to 05.

In step 5205, DIAG (diagnosis value calculated in step 5204) is 1. Preset tolerance width Δ
It is determined whether or not it is within the IR, and if it is within the allowable width ΔIR, the interrupt is terminated.

On the other hand, in step 5205, the diagnostic value I DIAG
If it is determined that the injector 10 is not within the allowable width ΔIR, the process proceeds to step 8206, where it is determined that there is a failure, and the diagnostic means 31 stores the trouble data of the injector 10 in which the failure has occurred in the non-volatile RAM 18a, and also warns of the occurrence of the failure. The self-diagnosis lamp 21 is turned on (flashing).

Therefore, circuit currents of different sizes supplied to a plurality of electric circuits can be detected with high viscosity by one current detection sensor 22, and it is possible to detect abnormal loads in electric circuits, poor contact of connectors, etc. Abnormalities such as ゜8 can be accurately determined.

Note that the drive pulse signal P1 for the injector 10 is
turns on and 1. If a control signal for another electric circuit is output after a predetermined time T1 and overlaps with the drive pulse signal Pi, the reference current value IR of each electric circuit is
The circuit state is determined based on the added value.

(Second example) Next, a second embodiment of the present invention will be described.

The second embodiment is the same as the first embodiment except that the function of the circuit current value calculation means 33 of the first embodiment is different.
The explanation will be omitted.

In the circuit current value calculation means 33 in the second actual droplet example, before the control signal of the electric circuit to be diagnosed is turned on and after the control signals to other electric circuits are turned off, the characteristics of the load are calculated in advance. When the reference time [)TIME or more has elapsed, which is determined according to
The circuit current 11 is calculated by subtracting LTO from the output of the current detection sensor 22 after a predetermined time has elapsed since the control signal was turned on.

In other words, when detecting the offset current value ILTO of the current detection sensor 22 for a certain electrical circuit to be diagnosed, as shown in FIG. However, the circuit current attenuates with a time constant determined by the load, and may not become O at the same time as the control signal is turned off. Therefore, until the circuit current is completely reduced, the output value of the current detection sensor 22 is the offset current value ILTO of the electrical circuit to be diagnosed.
Because the output value overlaps with the output value due to the decay current of other electric circuits, the control signal of the electric circuit to be diagnosed is turned on before the control signal of the other electric circuit is turned off. After the reference time D_TIME from when the circuit current is completely attenuated has elapsed, the offset current value I_LTO of the current detection sensor 22 is detected.

For example, the drive pulse signal P for the injector 10
When i is output, the reference time [)T elapses after the control signal output from the ECUI to other electric circuits turns off.
Check whether rHE has elapsed and set the reference time D TIHE
When the above period has elapsed, the offset current value I LTO is newly detected from the output of the current detection sensor 22 when the pulse signal Pi is turned ON, and this new offset current value I LTO is stored in a predetermined address of the RAM 18. The current offset current value ILTO is updated.

On the other hand, if the reference time [ without updating the
As in the first embodiment, the offset current value ILTO detected last time and stored at a predetermined address in the RAM 18 is used to calculate the circuit current.

Therefore, erroneous detection of the offset current value i LTO of the current detection sensor 22 due to the attenuation current after the control signal is turned off is prevented, and the circuit current value IL can be accurately calculated.

(Operation) Next, the operation confirmation procedure of the electric circuit in the second embodiment is as follows.
This will be explained according to the flowcharts in FIGS. 7(a) to (C).

First, when the control signal for the electric circuit is turned off, the interrupt program shown in FIG. is read from the free running counter.

Next, the process advances to step 5302 and the step 530 described above is performed.
The time Td read in step 1 is temporarily stored in the RAM 18,
Terminate the interrupt.

Next, when a control signal for starting injection for the injector 10 to be diagnosed, that is, a drive pulse signal indicated by P in FIG. 6, is output, the interrupt program shown in FIG. 7(b) is started, and step 5401 At step 5, the value of the free running counter is read again, and the time To when the drive pulse signal P1 is turned on is read.
Proceeding to step 402, the data is temporarily stored in the RAM 18.

Next, the process advances to step 5403, where the time Td saved in the RAM 18 in step 5302 in the previous interrupt program and the RΔM in step 5402 are stored.
Read the time To saved in 18 and calculate the time from when the control signal for the electric circuit turns off until the pulse signal P of the injector 10 to be diagnosed turns on.ΔT=To −Td ), step 540
Proceed to step 4.

In step 5404, it is determined whether or not the time ΔT calculated in step 5403 has reached the reference time [) TIME, and if it is determined that it has not reached the reference time [) TIME, step 5407 is performed. , if it is determined that the reference time D TIME has elapsed, the process advances to step 5405.

In step 5405, the trigger signal for starting A/D conversion output at time TO of the drive pulse signal Pi is
The signal is output to the converter 24, and the A/D converter 24 starts digital conversion of the output voltage signal of the current detection sensor 22.

In step 8406, the current detection sensor 2 at time TO is converted into a digital signal by the A/D converter 24.
Offset mainstream fm corresponding to the A rut voltage vO of 2
At ILTO, the offset current value ILTO stored at a predetermined address in the RAM 18 in the previous routine is updated.

Next, in step 5407, the A/D conversion 324 is
A/D conversion is started again after a predetermined time T1 has elapsed from the rise of the drive pulse signal P1 outputted to the injector 10 while outputting the D conversion completion signal No. 6.
The A/D conversion start time is set and the interrupt routine ends.

Next, when the predetermined time T1 has elapsed, an interrupt program shown in FIG. 7(C) is activated, and step 5501
Then, the A/D conversion of the output voltage signal of the current detection sensor I, l-22 is started again, and in step 5502, the current detection pin sensor 22 which is converted into a digital signal again by the A/D converter 24 is started. The output at time T1 shown in FIG.
The current value ILT1 corresponding to the voltage 1 and the voltage BV of the battery 23 converted into a digital signal by the A/D converter 24 are stored at different addresses in the RAM 18, respectively.

Next, proceeding to step 5503, the current value ILT1 corresponds to the offset current value ILTO of the current detection sensor 22 stored in the RAM 18 and the output voltage v1 of the current detection sensor 22 stored in step 5502. is read out from the RAM 18, and the A-fred current value ILTO is subtracted from the current value ILTI to obtain the circuit current value IL (IL=ILT1-ILTO), and the process proceeds to step 5504.

In step 5504, for example, R
The above injector 1 from the table stored in OM17
A reference current value In of 0 is obtained directly or by interpolation calculation, and a diagnostic value I DIAG is calculated from this reference current value 1 ft and the circuit current value I[σ obtained in step 5503 above (IDIAG=TI--IR ) and then proceeds to step 5505.

In step 5505, the diagnostic value I DIAG calculated in step 5504 is adjusted to a preset allowable range ΔI.
It is determined whether or not it is within R, and if it is within the allowable width Ilt, the interrupt is terminated.

On the other hand, if it is determined in step 5505 that the diagnostic value 101AG is not within the allowable range Δ[, step 85
The process proceeds to step 06, where it is determined that there is a failure, and the diagnostic means 31 stores the trouble data of the failed injector 10 in the nonvolatile RAM 18a, and lights up (blinks) the self-diagnosis lamp 21 that warns of the occurrence of the failure.

In addition, when detecting the offset current value I LTO,
Simply put, if the value is less than a predetermined value compared to the value previously detected and stored in the RAM 18, the RAM 1
If the value of 8 is updated and exceeds the predetermined value, the above RA
The value stored in M18 is set as the offset current value I LT
It may be used as O to calculate the circuit current value I[.

[Effects of the Invention] As explained above, according to the present invention, when detecting current by the current detection sensors provided on the power supply buses of a plurality of electric power lines, different currents depending on the load of the electric circuit are detected. The detection gain can be adjusted by changing the number of windings of the sensor's transformer, ensuring detection accuracy regardless of the magnitude of the current. Therefore, the current value of each electric circuit can be calculated accurately.
By comparing this current value with a preset reference current value, abnormalities in each electric circuit can be reliably detected without installing a current detection sensor for each electric circuit, and many external connections to each electric circuit can be detected. No need for an abnormality detection circuit,
It has excellent effects such as reducing costs, saving installation space, and improving reliability by reducing the number of connector bins.

[Brief explanation of the drawing]

1 to 5 show a first embodiment of the present invention, FIG. 1 is a functional block diagram of an abnormality detection device for an electric circuit according to the present invention, FIG. 2 is a circuit block diagram, and FIG. ) is an explanatory diagram showing the current detection sensor, FIG. 3(b) is a characteristic diagram of the current detection sensor, FIG. 4 is a waveform diagram of the control signal and current detection sensor output signal, and FIGS. 5(a) and (b) 6 and 7 show a second embodiment of the present invention, FIG. 6 is a waveform diagram of the control signal and current detection sensor output signal, and FIG. ) to (C) are flowcharts showing procedures for checking the operation of an electric circuit. DESCRIPTION OF SYMBOLS 1... Electronic control device, 25... Power supply bus, 22... Current detection sensor, 26a... Transformer, 34... Circuit state determination means, IL... Circuit current value, IR...・Reference current value. Figure 3■ Figure 4T. Figure 7 (b) (C)

Claims (1)

[Scope of Claims] An electric circuit abnormality detection device for detecting abnormalities in a plurality of electric circuits when the plurality of electric circuits are controlled by control signals, which includes: A current detection sensor equipped with multiple transformers whose detection gain can be adjusted according to the number of windings, and a current value calculated based on the output of the current detection sensor and a reference current value set in advance. An abnormality detection device for an electric circuit, comprising circuit state determining means for determining whether or not the electric circuit is normal.