JPH02168172A - Abnormality detecting apparatus of electric circuit - Google Patents

Abstract

PURPOSE:To correctly calculate a current of an electric circuit by updating an offset output value of a current detecting sensor only when a control signal is not output to the other electric circuits before a control signal of said electric circuit to be checked is turned ON. CONSTITUTION:An output value (offset output value) of a current detecting sensor 22 when no current runs in a power bus line 21 is stored in an offset output value storing means 34. Then, before a control signal of an electric circuit to be checked is turned ON and when a control signal is not output to the other electric circuits, an offset output value updating means 35 updates the offset output value read from the sensor 22 and stored by the memory means 34. Subsequently, a circuit current value calculating means 36 calculates a circuit current value I of the electric circuit to be checked based on the offset output value updated by the updating means 35 and the output value of the sensor 22 a predetermined time later after the start of output of a control signal to the electric circuit to be checked. A circuit state judging means 37 judges whether the electric circuit is normal through comparison of the current value I with a reference current value.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electric circuit abnormality detection WA device that detects abnormalities in a plurality of electric circuits connected to a power failure control device mounted on a vehicle or the like. .

[Prior art and problems to be solved by the invention] Generally,
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. IIa
It is driven by a control signal from the ll@ position. Recently, the above-mentioned electronic control I device has been combined with a function to diagnose whether the above-mentioned electric circuit is operating normally in response to the control signal. , a current sensor consisting of a shunt is installed on the power bus of a plurality of electric circuits. A technique has been disclosed that detects whether a control item is in a normal operating state by comparing the control signal with a current control signal.

However, in the above-mentioned prior example, the current of the power supply bus in which the current of the plurality of electric circuits is summed (when the heart is detected and an abnormality is detected, the control circuit outputs a control signal to the electric circuit individually, This control signal and the output signal of the current sensor are logically summed to determine the system in which the C abnormality has occurred.

For this reason, 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, increasing costs.
In addition, there were problems such as an increase in the installation space due to an increase in the number of circuit board mounting boards, and a decrease in reliability due to an increase in the number of connector bins for connection with the control circuit.

[Object of the Invention] The present invention has been made in view of the above-mentioned circumstances, and it determines the circuit current supplied to a plurality of electric circuits, determines the state of the electric circuit based on this circuit current, and detects an abnormality. An object of the present invention is to provide an abnormality detection device for an electric circuit that can detect an abnormality in an electric circuit.

[Means for Solving the Problems] An electric circuit abnormality detection device according to the present invention is an electric circuit abnormality detection device that detects abnormalities in a plurality of electric circuits when these electric circuits are controlled by a control signal. , a current detection sensor provided on the power bus of the electric circuit to detect the current supplied from the power bus to each electric circuit; and a current detection sensor that detects the current when no control signal is output to the electric circuit. Before the control signal of the electric circuit to be diagnosed is turned on and the control signal is not output to other electric circuits, the above-mentioned current is Offset output value updating means reads the output value of the detection sensor and updates the offset output value stored in the offset output value storage means, and checks the offset output value stored in the offset output value storage means! ! Ii After a predetermined period of time has elapsed since the start of control No. 13 output to the electric circuit to be diagnosed, calculate the circuit current value of the electric circuit to be diagnosed based on the output value of the upstream detection sensor height t) The circuit current value → The output means compares the output circuit current value with a preset reference current value and determines whether the electric circuit is normal or not. The calculation means are right.

[Function] With the above configuration, the output value of the current detection sensor when no current is flowing through the power supply bus, that is, the offset output value is stored in the offset output value storage means, and -
[The offset output value updating means updates the output value of the current detection sensor before the control signal of the electric circuit to be diagnosed is turned on and when no control signal is output to other electric circuits. is read and the A no-hit output value stored in the off-hit output value storage means is updated.

Thereafter, the circuit current value q output means determines the off-pit output value and the output value of the current detection sensor after a predetermined period of time has elapsed from the start of outputting the Luli control signal to the electric circuit to be diagnosed. A circuit current value of the electric circuit is calculated, and the circuit current value calculating means compares the circuit current value with a preset reference current value to determine 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 an 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. 3(a) 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) are diagrams showing the current detection sensor. ) is a flowchart showing a procedure for checking the operation of an electric circuit.

(Circuit Configuration) In FIG. 2, reference numeral 1 denotes an electronic control unit (ECU), which is installed in a vehicle such as an automobile and performs various controls such as engine control, transmission control, and air conditioner control.

This ECul includes a microprocessor (CPLJ) 2
, ROM3, RAM4, non-volatile RAM4a.

An output interface 5 and an input interface 6 are connected to each other via a path line 7.

Furthermore, an oscillator 2a is connected to the CPU 2, and is supplied with a reference clock at each timing. 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. The above various controls are carried out by the CP according to the control program stored in the ROM3.
This is performed by U2, and will be explained below using engine control as an example.

Transistors 11, 12, 13, etc. are connected to the output interface 5 through resistors 8,9, 10, respectively, and drive electric loads such as actuators each second. For example, the transistor 11 is connected to a current limiting resistor 15 and an injector 16, and the transistor 12 is connected to an idle speed control valve (
ISCV) 17 is connected. Furthermore, the above ECU
A current limiting resistor 18 and an ignition coil 19 are connected to the transistor 13 provided outside of I. Further, a self-diagnosis lamp 14 is connected to the output inlet 5 to inform of abnormality in the control system.

Further, a current limiting resistor 15 to an injector 16 to a transistor 11, a current limiting resistor 17 to a transistor 12, and a current limiting resistor 18 to an ignition coil 19 to a transistor 13 are connected to a power source fn line 21 extending from the battery 20. , each constitute an electric circuit. Battery 2 above
The circuit current I[ supplied from 0 to each electric circuit is directly detected by the current detection sensor 22 provided on the power supply bus 21.

As shown in FIG. 3(a), the circuit current detection sensor 22 has an annular core 23 made of, for example, ferrite.
A transformer is formed by winding electric wires around the annular core 2.
3, a Hall element 24 is disposed in the opening, and an amplifier 25 is connected to the ball element 24, and the whole is molded with, for example, resin.

When a control signal is output from the source bus 21 to each electric circuit and a current flows, a magnetic field is generated by this current, and a magnetic flux penetrates the Hall element 24 by the transformer made of the core 23. Voltage is generated. The voltage generated in the Hall cable 24 is amplified and output by the amplifier 25, and a voltage approximately proportional to the current is output.

The characteristics of the current sensor 22, as shown in FIG. When there is no input signal, a slight voltage exists at the output as an offset output value VO due to electrical variations in the output voltage.

On the other hand, the current detection sensor 22 and battery 20 are connected to the input interface 6 via an analog-to-digital converter (A/D converter) 26, and the output voltage of the current detection sensor 22 and battery 20 is A/D
The signal is converted into a digital signal by the converter 26 and input. Further, the input interface 6 includes, for example,
Control sensors 27 such as an intake air amount sensor, a crank angle sensor, and an 02 sensor are connected.

The ROM 3 stores fixed data such as control programs, and the RAM 4 stores the output values from the cylinder sensor 27 after data processing and the output values processed by the CPLJ 2. Data is stored. In addition, the non-volatile RAM 48 includes the actuators 16, 17, 19, control sensors 27, or
Trouble data when a failure occurs in the control system is stored, and is backed up by the battery 20 so that the stored trouble data is retained even when a key switch (not shown) is turned off.

The CPU 2 calculates various control data based on the scale data stored in the RAM 4 according to the control program stored in the ROM 3. The CPU 2 temporarily stores the calculated various control data in the RAM 4, and outputs the data to the actuators 16, 1 via the output interface 5 at a predetermined timing.
It outputs a control signal to the electric negative M such as 7.19, performs various controls such as air-fuel ratio control, idle rotation speed control, and ignition timing system I, and also performs self-diagnosis by determining the status of each electric circuit. When an abnormality is detected, the self-diagnosis lamp 18 is turned on (flashing) to notify the driver of the abnormality, and trouble data indicating the details of the abnormality is stored in the non-volatile M4a.

(Akebono composition) Next, the functional configuration of the ECUI will be explained.

As shown in FIG.
2 (part of the ROM3, RAM4 and non-volatile RA)
M4a), output processing means 33, offset output value storage means 34 (consisting of a predetermined address of RAM4),
It is composed of offset output value updating υi means 35, circuit current value calculating means 36, circuit current value calculating means 37, and self-diagnosis means 3B.

Above it, II I! II parameter input processing means 30
Then, the output signals from the control sensors 27 such as the intake air amount sensor, crank angle sensor, and 02 sensor for detecting control parameters are subjected to waveform shaping or analog-to-digital conversion processing, and are stored in the storage means 32. Store.

The calculation processing means 31 calculates various control data based on the signals from the control sensors 27 taken in by the input horn means 30 according to the control program stored in the storage means 32.

In the output processing means 33, the arithmetic processing means 31 calculates τ
) Outputs various control data and injector 1
6, l5CV17, ignition: +I Drive various electric negative parts such as Az19.

[Above] In the offset output value storage means 34, the power supply bus 21
The output value of the commercial detection hinge when no current is flowing is stored as an offset output value. That is, since the current detection sensor 22 has a six-onset voltage VO at its output when there is no input signal, the current detection sensor 22
The offset output value of 2, that is, the offset current value corresponding to the offset voltage VO is detected by the current detection sensor 22.
The initial output of the current detection sensor 22 is stored and held at a predetermined address in the RAM 4, and the calculation of the circuit current, which will be described later, is performed from the curved waveform of the output of the current detection sensor 22.

In the offset output value updating means 35, the offset voltage vO is not always constant and is not 4, but fluctuates due to the influence of drift due to temperature changes, changes over time, etc., and also has variations due to individual differences. Before the control signal of the electric circuit is turned on, and when no control signal is output to other electric circuits, the output value of the upper closed current detection sensor 22 is read, and this output value is used to set the off-hit output la. The offset output value VO stored in the storage means 34 is updated.

1. In other words, the above “J” for the electrical circuit to be diagnosed.
When detecting the offset "m ffl value of the u current detection sensor 22, if the other electric circuit Heshi II I2+1 signal is output, as shown in FIG. 4, the output value of the current detection sensor 22 will be In this case, the output value will be a combination of the offset current value of the electrical circuit to be diagnosed and the current value due to the circuit current of another electrical circuit.Therefore, no circuit current is flowing in the electrical circuit that is being diagnosed at the clinic. , and the offlet output value VO of the current detection sensor 22 may be detected as long as no circuit current is flowing in any other electric circuit.

For example, the drive pulse signal P for the injector 16
When i is output, it is checked whether or not a control signal is output from the output processing means 33 to other electric circuits, and the &11m signal is output from the output processing means 33 to other electric circuits. When the pulse signal Pi is ONt
The offset current @ l LTO is newly detected from the output of the current detection sensor 22 at the time of Update.

On the other hand, the control 6 from the output processing means 33 to the electric circuit of
When the D signal is being output, the offset current value ILTO stored at a predetermined address in the RAM 4 is not updated, but is stored in a predetermined address in the RAM 4 detected last time when calculating a circuit current, which will be described later. Use the offset current value ■LTO.

The circuit current l11i extraction means 36 outputs data from the output processing means 33 to the "electrical circuit a, II t" to be diagnosed.
When the all signal is output), the output of the current detection sensor 26 is read after a predetermined period of time has elapsed since the start of output of this control signal, and the current value corresponding to this output value is stored in the offset output value storage means 34. The stored offset current value ILTO is reduced to eliminate the influence of the offset voltage (2) 0, and the circuit current value IL of the electric circuit to be diagnosed is falsified.

That is, taking the above-mentioned injector 16 as an example, the current value 1 [■ 1
Then, the current value ILTO corresponding to the offset voltage VO of the current detection sensor 22 when the control signal output to the injector 16 is ON, which is stored in the offset output value storage means 34, is subtracted from n to obtain the actual value of the electric circuit. The circuit current value It (IL = ILTI - ILTO) is determined and this is repeated for each pulse.

Therefore, when calculating the circuit current of the electrical circuit to be diagnosed, the offset current value I LTO stored in the offset output value storage means is Detected offset current 1
If allTO is used as is and no control signal is output to other electrical circuits, the newly detected off bit current +1Q[lTO will update (11'1 of the offset output value 210 means 3t1). Then, the circuit current value IL is calculated based on this updated offset and the current value ILTO.

1. In other words, false detection due to overlapping control signals is prevented,
The circuit current value IL can be calculated accurately.

In addition, in the case of an inductance load such as the above-mentioned injector 16, the current waveform i as shown by 1inj in FIG.
, lj control signal voltage pulse signal Pi), the rise of the current is delayed with respect to the control signal voltage pulse signal Pi). In case of electric load or lamp load, there is no phase delay of the current with respect to the control signal voltage and the current rises at the same time as the control signal voltage is turned on. The LTO may also be read.

The circuit current value calculation means 37''r- is the circuit current fl11 of the electric circuit calculated by the circuit current value calculation means 36.
il and the group 1N! stored in the storage means 32. Current value I
Check with R to determine whether the electrical circuit is normal or not.

- written base tI! Current (self IR is, for example, battery 20
Using the heavy pressure BV as a parameter, the reference current value lR preset from the characteristics of each electrical load in the electric circuit is stored as a table in the storage means 32N4.
3>, and the upper one injector 16
When the pulse signal Pi is outputted, the reference current value IR is determined using the current fluctuation voltage BV as a parameter, either directly from the table or by interpolation. The above circuit current value calculation f: stage 3 with respect to this reference current value IR
Circuit current calculated in step 6! By determining whether 1ilL is within a preset allowable width ΔIR, it is possible to determine whether the state of the electric circuit is normal.

In the self-diagnosis means 38, the circuit current value calculation means 3
7, when it is determined that there is an abnormality, the trouble data is stored in the storage means 32, and an abnormality signal is output to light (blink) the self-diagnosis lamp 14 to notify the abnormality of the electric circuit.

Incidentally, the trouble data stored in the storage means 32 is stored at 1 hour when the φ vehicle enters the service station (dealer).
By connecting an external device, such as a vehicle diagnostic device, to the ECUI, the information can be read out, thereby making it possible to easily identify the target of the abnormality.

(Operation) Next, the procedure for checking the operation of the electric circuit with the above configuration will be explained in the fifth section.
The explanation will be given according to the diagram.

Although the injector 16 will be described as an example of the electrical load, the same applies to other electrical loads such as the ISC 17 and the ignition coil 19.

Control signal to start injection to the injector 16, ? When the drive pulse signal Pl shown in FIG. 4 is output, the interrupt block 1 shown in FIG.
A trigger signal for starting A/D conversion is output to the A/D converter 26 from the rising edge of II TO at time i,
The A/D converter 26 starts f-digital conversion of the output voltage signal of the upstream detection sensor 22.

Next, the process proceeds to step 5102, where the state of the boat is read from the output address of the control signal for each electric circuit of the output interface 5, and the process proceeds to step 5103. Step 3103 (") determines whether or not a control signal is being output to other electric circuits based on the state of the boat read in step 8102 above, and it is determined that no control signal is being output to other electric circuits. Then, the process advances to step 5104.
On the other hand, when it is determined that the control signal 11 is output to another electric circuit and the control signal C is present, the process advances to step 5105.

When it is determined in the step 5103 that the control signal is not output to other electric circuits, in the step 5104, the current detection sensor 1 at the time TO converted into a digital signal by the A/D converter 26 is processed. 22 offset voltage ■ Current value I LTO corresponding to 0, stored at a specified address in RAM4 in the previous routine? Update the offset current 1+141 LTO.

Next, in step 5105, the A/D converter 26
A/D conversion end signal is output, and A/D conversion is started again after a predetermined time T1 has elapsed since the rise of the drive pulse signal P output to the injector 16.
/D conversion start time is set and the interrupt ends.

The predetermined time T1 is, for example, in the case of a load that twists the inductance to the right, such as the injector 16, as shown in FIG.
As shown by inj, since the current value varies depending on the elapsed time from when the Ll control signal becomes ONl to reaching the steady current value, it is set appropriately according to the characteristics of the load.

Next, when the predetermined time T1 has elapsed, FIG. 5, (1)
) is started, and in step 5201, A/D* conversion of the output voltage signal of the current detection sensor 22 is started again, and in step 5202,
The A/D converter 26 converts the current value I LTI corresponding to the output voltage of the current detection sensor 22 at time T1 shown in FIG. The voltage BV of the battery 20 converted into a digital signal is stored at a different address in the RAM 4, respectively.

Next, when the process proceeds to step 5203, the offset voltage v of the current detection sensor 22 stored in the RAM 4 is
The offset current value I LTO corresponding to O and the current 1 series I LTI corresponding to the output voltage v1 of the current detection sensor 22 stored in step 3202 are stored in the RAM/
The circuit current value ■[(+1
-ILTI-ILTO) is zeroed out, step 520
Proceed to step 4.

In step 5204, for example, RO
From the daple stored in M3 to the injector 16
Find the reference current value IR directly or by interpolation,
This reference current 1+fi I R and the above step 5203
From the circuit current value IL obtained at , the diagnostic value I DIA
GJ! j-calculation (IDIAG=IL-IR) L,
Then proceed to suite 5205.

In step 5205, the diagnostic value IO[AC sieved out in step 5204 is determined by a preset allowable width ΔI
Determine whether or not it is within R, and set the allowable width Δ[If it is within R, υ1
Finish loading.

On the other hand, in step 5205, the diagnosis 1i 1 DI
If it is determined that AG is not within the allowable range ΔIR, the process proceeds to step 3206, where it is determined that there is a failure, and the self-diagnosis unit 138 stores the trouble data of the injector 16 where the failure has occurred in the non-volatile RAM 4a, and also stores the trouble data of the injector 16 where the failure has occurred. The self-diagnosis lamp 14 is set to blink (flashing) to warn of this.

Therefore, when dedicating the circuit current of the electric circuit to be diagnosed, the offset current sensor [L] of the current detection sensor 22 is
Erroneous detection of TO is prevented and the circuit current is ejected accurately.
Abnormalities in loads in electric circuits, poor connections in connectors, abnormalities in transistors 11, 12, 13, etc. can be accurately determined.

Incidentally, the drive pulse signal P1 for the injector 16
When a control signal for another electric circuit is output after a predetermined time T1 has passed after turning ON and overlaps with the drive pulse signal Pi, the circuit is controlled by the shore line of IJ\-current value IR of each electric circuit. Determine the status.

[Effects of the Invention] As explained above, according to the present invention, the current is detected by the current detection sensor provided on the power bus of a plurality of electric circuits, and the circuit current of each electric circuit is detected. The offset output value of the current sensor is updated only when the control signal of the electric circuit to be diagnosed is turned on and no control signal is output to other electric circuits. , otherwise, the offset output value is stored and held as is.Then, the offset output value and the current detection sensor of the current detection sensor after a predetermined period of 11) have elapsed from the start of the control signal horn to the electric circuit to be diagnosed. From the output value,
Since the circuit current value of the electric circuit to be diagnosed is calculated, even if multiple control signals overlap, the circuit current of each electric circuit can be accurately outputted as C1, and compared with the preset reference current value. This makes it possible to reliably detect abnormalities in each electrical circuit. Therefore, by connecting many external circuits to each electrical circuit, there is no need for an abnormality detection circuit, and there is no need to increase costs, increase installation space, or reduce reliability due to an increase in the number of connector pins. Qin has excellent effects such as being able to be detected.

[Brief explanation of the drawing]

1 to 5 show an 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. 3(a) is an explanatory diagram showing the current detection sensor, FIG. 3(b) is a characteristic diagram of the current detection sensor, and FIG. 4 is 1. II The waveform diagram of the t21+ signal and the current detection sensor output signal, Figure 5 (a> and (b)) is a flow diagram that reduces the procedure for checking the operation of the electric circuit. - Power supply bus, 22...Upstream detection sensor, 34...Offset output value storage means, 35...A noset output value updating means, 36...Circuit current (illi
Calculation means 37...Circuit current value calculation means, l LTO...Offset current value, I[...Circuit current value, fR...Reference current value T. Book T. Figure 5(b)

Claims (1)

[Scope of Claims] An electric circuit abnormality detection device for detecting an abnormality in a plurality of electric circuits when the plurality of electric circuits are controlled by control signals, wherein the electric circuit abnormality detection device is provided on a power supply bus of the electric circuit; a current detection sensor that detects the current supplied to each electric circuit from the power supply bus; an offset output value storage means that stores an offset output value of the current detection sensor when no current is flowing through the power supply bus; Before the control signal of the electric circuit is turned on and when no control signal is output to other electric circuits, the output value of the current detection sensor is read and the offset output stored in the offset output value storage means is generated. an offset output value updating means for updating a value; and an offset output value stored in the offset output value storage means and an output value of the current detection sensor after a predetermined period of time has elapsed from the start of outputting a control signal to the electric circuit to be diagnosed. and a circuit current value calculation means for calculating a circuit current value of the electric circuit to be diagnosed, and a circuit current value calculated by the circuit current value calculation means is compared with a preset reference current value, An abnormality detection device for an electric circuit, comprising circuit state determining means for determining whether or not the electric circuit is normal.