JPS622307A - Diagnostic device - Google Patents

Abstract

PURPOSE:To store efficiently and at a low cost the magnitude of a driving signal and a counter-electromotive voltage by eliminating a counter-elctromotive voltage component from the driving signal and fetching a digital signal, and also obtaining level information of two bits by comparing the counter- electromotive voltage with a limit value. CONSTITUTION:A solenoid driving signal A from an input terminal 11 is converted to a digital signal for showing on and off, after the counter- electromotive voltage component has been eliminated by a waveform shaping circuit 10 and inverted by aninverter 12 and an output signal C is obtained. On the other hand, the signal A is compared with the upper and the lower limits VREF1, VREF2 by comparators 13, 14, respectively, and in accordance with whether it is within a range of the upper and the lower limits or not, a binarization signal is outputted. By this output, FFs 15, 16 are set and reset, and signals F, H are obtained in an output Q. The signal F is brought to exclusive OR with the signal H and a signal G is outputted. When this signal G and H are stored in a storing circuit, and OR of both of time is fetched at the time of reproduction, each period of solenoid on and off signals can be known, and in which level the counter-electromotive voltage is can be known.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention provides a system for diagnosing failures in electromagnetic solenoids and their control systems used in various control systems of vehicles, etc.
The present invention relates to a diagnostic device that stores solenoid drive signals.

(Prior Art) Conventionally, as a signal storage device used for diagnosing system abnormality by monitoring the operating state of a vehicle control system, for example, the operating state of an electromagnetic solenoid that drives a fuel injection valve, A diagnostic device has been proposed in which the cause of a failure can be investigated by A/D converting a signal, storing it in a memory as it is, and reproducing the stored data (Japanese Patent Application No. 54-130846, etc.).

FIG. 3 shows an outline of such a conventional diagnostic device, which includes a sensor 1 as a control system, a control circuit 2, an electromagnetic solenoid 3 as an actuator, and connectors 4 and 5.
A drive signal from the control circuit 2 is input to the memory circuit 7 through the signal line 8, and the write command circuit 6 writes and stores the drive signal in the memory circuit 7 chronologically at a predetermined timing,
By later reproducing the stored contents of the memory circuit 7, failure diagnosis can be performed when an abnormal operation occurs in the electromagnetic solenoid 3.

However, as a practical matter, the memory capacity of the memory circuit 7 is limited, so a circuit equipped with a timer 10a as shown in FIG. 4 is used, and the timer 10a is started at a predetermined timing, and the Only the data for the period is stored.

For example, when the engine start switch 11a is turned on, the timer 1
0a is activated, a timer output obtained over time T is given to the AND gate 12a, and the AND gate 12a outputs a write clock 14a from the oscillator 13a for a certain period of time to write data into the memory circuit 7.

(Problems to be Solved by the Invention) However, even in a device that stores data for fault diagnosis only for a certain period of time, there are the following problems.

First, in order to accurately detect malfunctions in the electromagnetic solenoid, it is necessary to sample and write memory data at an early timing determined by the on/off cycle of the solenoid drive signal that controls the solenoid valve on a duty basis. If the on/off period of the electromagnetic solenoid is 100 m5, the sampling rate will be extremely high-speed timing of 1 mS or less, so storing the data as time-series data over a predetermined period will require an enormous storage capacity.

Further, even if data is stored only for a predetermined period, a problem does not necessarily occur during that period, and stored data for fault diagnosis may not always be obtained after all.

On the other hand, in order to diagnose the failure of the electromagnetic solenoid itself, it is necessary to know not only the ON/OFF period of the solenoid drive signal but also the magnitude of the back electromotive force generated when the solenoid is OFF. In order to know the level of the back electromotive force, the data obtained must be converted into, for example, an 8-bit digital signal and stored, and as the number of bits of stored data increases, the storage capacity of the storage circuit further increases, reducing costs. There was also the problem that it was expensive.

(Means for solving the problems) The present invention was made in view of the above problems, and
An object of the present invention is to provide an inexpensive diagnostic device capable of storing ON/OFF drive signals of an electromagnetic solenoid and the magnitude of a back electromotive voltage generated when the solenoid is OFF without increasing the storage capacity.

In order to achieve this objective, the present invention performs waveform shaping to remove the back electromotive voltage component included in the solenoid drive signal to extract a digital signal synchronized with the solenoid on/off signal. A storage circuit that outputs 2-bit level information in synchronization with the digital signal, indicating which of three levels (above the upper limit, between the upper and lower limits, and below the lower limit) the level is in comparison with the upper and lower limits set in advance. write to,
The on/off duty, the level of the back electromotive force, etc. can be determined from this stored data.

(Embodiment) FIG. 1 is a circuit block diagram showing an embodiment of the present invention.

First, to explain the configuration, numeral 11 is an input terminal to which a solenoid drive signal (A> written in the memory circuit) is applied.
This solenoid drive signal has a signal waveform shown in FIG. 2 (A>) in which an on/off signal for duty-controlling the electromagnetic solenoid and a back electromotive force generated when the solenoid is turned off are superimposed.

A waveform shaping circuit 10 removes a back electromotive force component contained in the solenoid drive signal from the input terminal 11 and outputs a digital signal synchronized with the solenoid on/off. 1
2 is an inverter that inverts the output of the waveform shaping circuit 10, and the output of the inverter 12 is connected to the RS flip-flop 1.
5 reset human power R.

On the other hand, comparators 13 and 14 are provided to compare and judge the magnitude of the back electromotive force included in the solenoid drive signal (A>.The negative input of the comparator 13 has the upper limit of the back electromotive force when the solenoid is normal. Reference voltage V
ref1 is set, and a reference voltage yr'er2 that provides the lower limit of the back electromotive force when the solenoid is normal is set at the negative input of the comparator 14. That is, the comparators 13 and 14 have an upper limit ref1 and a lower limit Vref2.
A window comparator is configured with a threshold value of Then, it becomes (1, O).

The outputs of the comparators 13 and 14 become the setting force S of the RS flip-flops 15 and 16, respectively.

The Q output of the RS flip-flop 15 is given to one input of the EX-OR 17, and the other input is given to the waveform shaping circuit 1.
An output of 0 is given.

This RS flip-flop 15.16 and EX-OR1
The circuit section 7 converts the 2-bit level information indicating the level of the back electromotive force obtained through the comparison and determination of the comparators 13 and 14 into the timing of the digital signal from the waveform shaping circuit 10 indicating the solenoid on/off cycle. By synchronously outputting, it has a circuit function as a signal processing means that causes a data writing circuit (not shown) to write into a storage circuit.

Next, the circuit operation will be explained with reference to the timing chart of FIG. 2 showing signal waveforms of each part in the embodiment of FIG. 1.

First, the solenoid drive signal to the input terminal 11 is
As shown in the diagram (A>), the solenoid has a predetermined on/off cycle, and the back electromotive force generated in the solenoid is superimposed at the timing of the solenoid turning off.

The waveform shaping circuit 10 removes the back electromotive voltage component from this solenoid drive signal (A>, and converts it into a digital signal of "0, 1" indicating whether the solenoid is on or off. The output of this waveform shaping circuit 10 is inverted by the inverter 12 to obtain a signal waveform as an output (C).

On the other hand, the solenoid drive signal @ (A) is the comparator 13
, 14, the upper limit Vref1 and the lower limit Vref2, respectively.
For example, at time t1, the output is within the upper and lower limits, so the output of the comparator 13 is "O" and the output of the comparator 14 is "1". Furthermore, at time t2, since the lower limit Vref2 is below, the outputs of the comparators 13 and 14 are both rOJ.
becomes.

Furthermore, since the upper limit Vref1 is exceeded at time t3, the outputs of comparators 13 and 14 are both "
1”.

RS flip-flops 15 and 16 are comparators 13,
It is set by the output "1" of the inverter 14, and is reset by the rising edge of the output (C) of the inverter 12 obtained subsequently,
As a result, the output Q of the RS clip-flop 15 has the signal waveform shown in FIG. 2(F). Further, the Q output of the RS flip-flop 16 has a signal waveform shown in FIG. 2(H).

Further, the Q output of the RS flip-flop 15 is input to the EX-OR 17 together with the output (B) of the waveform shaping circuit 10,
This output (E) is as shown in FIG. 2 (G). Here, the output (G) of EX-OR17, which is the final output, and the RS
Looking at the Q output (H) of flip-flop 16, the following table-1
become that way.

In other words, in normal conditions when the back electromotive voltage is within the upper and lower limits, the outputs (G) and (H) are (1, 1>), when they exceed the upper limit, they are (0, 1), and below the lower limit, ( 1', O)
becomes. Final output signal (G) further written to the memory circuit
, (H) are extracted by the OR gate 18 as shown by the dotted line in FIG. 1, and as shown in FIG. 2 (1),
This signal waveform corresponds to a digital signal synchronized with the solenoid on/off from which the back electromotive force component was removed by the waveform shaping circuit 1Q, and therefore the signal output (G).

By storing (H) in a memory circuit and taking the logical sum of the two during reproduction, each cycle of the solenoid ON and OFF signals can be determined. Of course, if the range of the back electromotive voltage is within the normal range, that is, within the upper and lower limits, the on/off cycle can be known from either the control output (G) or (H).

Next, writing of 2-bit digital information including on/off pulse width and back electromotive force level information obtained in the embodiment of FIG. 1 into the storage circuit will be explained.

First, the number of signal bits required for data writing is 2 bits, and if the on/off period of the electromagnetic solenoid is, for example, 100 m5, the sampling rate for writing is set to 1 mS in order to check the duty ratio on the order of %. Just do it. As a result, the memory capacity required to write data per second is (1 sec 10.001 sec) x 2 bits
= 2000 bits. On the other hand, when storing the solenoid drive signal as it is after A/D conversion without data processing as in the present invention, the sampling time is about 0.1 m5ec, considering the extremely short time of generation of back electromotive force. For example, 8 bits are required because the number of bits of the stored data needs to represent the level of the back electromotive voltage. Therefore, the memory capacity for storing data for 1 second is (1sec 10.0OO1sec)x8bit=8
0000 bits, and requires 40 times more memory capacity than the present invention. This proves that the storage capacity is significantly reduced by the signal storage of the present invention.

The above embodiment takes as an example the storage of data regarding the solenoid drive voltage for duty control to maintain the opening of the solenoid valve at a predetermined flow rate by fuel injection or appropriate fluid control. The invention is not limited to this, and any appropriate signal waveform can be applied as is as long as it is a drive signal that turns on and off the electromagnetic solenoid.

(Effects of the Invention) As described above, according to the present invention, in a diagnostic device that stores in a storage circuit the ON/OFF drive signal of an electromagnetic solenoid and the back electromotive force generated when the solenoid is OFF, which is included in the drive signal, the solenoid Waveform shaping is applied to remove the back electromotive force component included in the drive signal, and the solenoid is turned on.
A digital signal synchronized with the off signal is taken out, and the back electromotive force is compared with the predetermined upper and lower limits to determine the voltage in three stages (above the upper limit,
Since the 2-bit level information indicating whether the level is between the upper and lower limits or below the lower limit is output in synchronization with the digital signal and written into the memory circuit, the solenoid drive signal can be simply Compared to conventional devices that perform A/D conversion and store data as is, the number of data bits is smaller.
Storage capacity can be significantly reduced without compromising information content.

Furthermore, since a single signal is converted into 2-bit data, that is, 2 systems of data, and stored, redundancy in circuit processing for data storage can be improved. For example 2
Even if one of the bits of write data causes a write error, it is possible to reproduce the original signal from the other correctly written data.

Further, since data processing is performed to determine an abnormality regarding the appropriateness of the pulse width and back electromotive voltage at the stage of data writing, abnormality diagnosis during data reproduction can be performed quickly and efficiently.

[Brief explanation of the drawing]

Fig. 1 is a circuit block diagram showing an embodiment of the present invention, Fig. 2 is a timing chart showing signal waveforms of each part in the embodiment of Fig. 1, and Figs. 3 and 4 are block diagrams showing a conventional example. Illustrated. 1: Sensor 2: Control circuit 3: Actuator 4.5: Connector 10: Waveform shaping circuit 11: Input terminal 12: Inverter 13.14: Comparator 15.16: RS flip-flop 17: EX-OR (exclusive OR) Patent Applicant Nissan Motor Co., Ltd.oooooooo.

Claims (1)

[Scope of Claims] A device for diagnosing failures in electromagnetic solenoids and their control systems by recording on/off drive signals of electromagnetic solenoids and back electromotive voltages included in the drive signals when the solenoid is off in a memory circuit. a waveform shaping means for removing a back electromotive voltage component included in the solenoid drive signal and outputting a digital signal synchronized with the solenoid on/off signal; and comparing the back electromotive voltage with predetermined upper and lower limits; level comparison means for outputting 2-bit level information representing either above the upper limit, within the range of the upper and lower limits, or below the lower limit; A diagnostic device comprising: signal processing means for outputting level information to the storage circuit.