JPH04231838A - Trouble diagnostic apparatus for automobile - Google Patents

Abstract

PURPOSE:To easily and accurately detect the trouble of an automobile by properly performing the momentary interruption of a level signal and a pulsating signal and giving proper judging standards corresponding to the respective signals. CONSTITUTION:For example, a trouble diagnosing apparatus for an automobile is equipped with a control unit 50 constituted using a microcomputer and the unit 50 has a level judging part 51 judging a signal level and a propriety judging part 52 judging the propriety of the signal judged in its level on reference to a judging standard and the signal from a line to be diagnosed is inputted to the level judging part 51 through an input terminal. The unit 50 is connected to a buzzer 53 and a lamp 54 displaying a judgment result. The level judging part 51 has the thresholds corresponding to the levels of various signals and the propriety judging part 52 has the judging standards l-4 corresponding to those signal levels. By this constitution, the momentary interruption of a level signal and a pulsating signal is properly performed and the proper judging stadards corresponding to the respective signals are given and, therefore, the trouble of a car can be accurately detected.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for diagnosing failures in automobiles, and more particularly to an apparatus for diagnosing failures in electrical systems.

0002

2. Description of the Related Art Conventionally, a tester has generally been used to diagnose and detect failures in the electrical system of an automobile. However, testers can only detect simple failures such as disconnections, and cannot detect complex failures. In particular, many modern automobiles are equipped with sophisticated electronic control devices, and there are limits to the failures that can be detected by testers. For this reason, when a control system such as a sensor controlled by an electronic control device, an ignition system, a fuel supply system, etc. is malfunctioning, it is difficult to pinpoint the location of the malfunction accurately. A situation may arise in which even normal parts are replaced.

[0003] To solve this problem, in order to accurately diagnose and detect a failure location, a failure detection device becomes large-scale and expensive, and advanced knowledge or technology is required to make full use of this failure detection device. Another problem arises in that it is necessary.

0004

[Problem to be solved] For this reason, a device with a relatively simple configuration for detecting failures in the electrical system of a vehicle equipped with the above-mentioned electronic control device has been proposed. The problem is that the scope of application is narrow and, in practice, failures cannot often be detected accurately. Therefore, an object of the present invention is to provide a fault diagnosis device for an automobile that has a simple configuration and can properly and easily detect faults.

[0005]

[Means for Solving the Problems] In order to achieve the above object, the present invention is constructed as follows. That is, the automotive failure diagnosis device according to the first feature of the present invention includes instantaneous power failure detection means for detecting that no signal is continuously input for a predetermined period of time, raw signal input means for accepting pulse input signals as they are, and a first counting means for counting and outputting a signal each time a predetermined number of pulse signals are input; and a first counting means for counting and outputting a signal every time a predetermined number of pulse signals are input; a second counting means for outputting, a display means for displaying the input when a signal is input, the instantaneous interruption detection means, the raw signal input means, the first counting means and the second counting means.
The apparatus is characterized by comprising a switching means for selectively connecting the counting means to the display means.

[0006]Furthermore, the automotive failure diagnosis device according to the second feature includes a pulse generating means for generating a pulse signal, a current amplifying means for amplifying the current of the pulse signal from the pulse generating means, and at least two different voltage values. power supply means capable of supplying power to the current amplification means at
Voltage changing means changes the connection state between the current amplifying means and the power supply means to change the voltage supplied to the current amplifying means, and the voltage of the output from the current amplifying means is changed according to the object. It is characterized by

[0007] In a preferred embodiment of the invention, an apparatus is constructed that incorporates both the first and second features. The functions of each of the above features can be switched using a switch. In addition, above 1
In the feature, there is preferably a display between the display means and the instantaneous interruption detection means, the raw signal input means, the first counting means, and the second counting means so that the display by the display means can be confirmed by human senses. A display guarantee means is provided to ensure that.

[0008] The predetermined period detected by the instantaneous interruption detection means is 0.1 m when a pulse signal is input.
Set to seconds or more. Moreover, in the case of a level signal, it is preferable to set it shorter than this. Furthermore, the frequency of the pulse signal generated in the second feature of the above device can preferably be changed within the range of 1 to 1 KHz.

[0009] The display means can be composed of, for example, a light emitting diode or a buzzer. The voltage changing means is capable of applying, for example, 12 volts, 5 volts, or a value in between. In still another aspect of the present invention, an automotive failure diagnosis device includes a level signal determining means for determining the level of a level signal, and a standard setting for providing a signal determination criterion according to the level determined by the signal level determining means. and a signal generating means that generates a signal when the input signal to the reference setting means continues to exceed the determination criterion for a predetermined period of time.

[0010] In this aspect, the signal to be determined is a stationary signal such as a DC signal. Therefore, a line connected to battery power or a line connected to a converter for supplying power to various sensors is used. , the control unit's power line or ground line, etc. In this case, for example, when checking a line that uses battery power, 9V or more, and when checking a control unit power line, etc., 4.8V to 5.3V.
When checking the V range and earth line, the range is 0.0V to 0.
．． Thresholds are provided for each signal level in the 2V range and, for sensor output line checking, in the 0.3V to 4.7V range. This determines the signal level corresponding to the input signal, that is, the signal from the line to be diagnosed. Criteria for determining the suitability of this signal are set corresponding to each signal level.

[0011] Furthermore, in another aspect, the automotive failure diagnosis apparatus includes: value detection means for detecting the value of the pulsation signal; reference setting means for setting a criterion for determining the pulsation signal based on the value; a frequency storage means for measuring and storing the frequency of the signal according to a standard set by the reference setting means; and a signal generating means for generating a signal when the frequency of the input signal exceeds a predetermined value. It is characterized by having

In this case, there is a means for visually displaying the signal from the signal generating means, and a means for inputting a signal corresponding to the engine speed and visually displaying the engine speed or a signal corresponding thereto. It is preferable to provide Instead of the above-mentioned visual display, means for generating a sound corresponding to the signal from the signal generating means may be provided.

Furthermore, in another aspect, a fault diagnosis method for an automobile is provided, in which the signal level of an input signal is determined, and the appropriateness of the input signal is determined in accordance with the determined signal level. determining whether the input signal matches the criteria in reference to the criteria corresponding to the signal level, and determining whether the input signal does not meet the criteria of the criteria. If this continues for a predetermined period of time, it is determined that the input signal is not appropriate.

In yet another automotive fault diagnosis method, the value of the input pulsation signal is measured, a criterion for determining the suitability of the input pulsation signal is set based on the measured value, and after a predetermined period of time the input pulsation signal is determined. A reference frequency is set by measuring the frequency of the input pulsation signal according to a determination criterion, and thereafter, when the frequency of the input pulsation signal is lower than the reference frequency, it is determined that the input pulsation signal is inappropriate.

In this case, in a preferred embodiment, when the frequency of the input pulsation signal measured according to the criterion after a predetermined period falls below the reference frequency when the engine speed is within a predetermined range, the input pulsation signal is not appropriate. It is determined that Although the present invention can be configured using an IC,
The above functions can also be configured using a microcomputer.

[0016]

[Operation] The failure detection device for an automobile according to the present invention is connected to the power supply line, ground line, etc. of each electrical device, starts the engine, and detects a momentary disconnection, that is, a momentary disconnection state. Furthermore, it is determined whether the pulse signal is being generated properly by connecting to appropriate lines of the control system such as a sensor, ignition system, or fuel control system.

Furthermore, each component such as the ignition system and fuel supply system is operated separately from the engine operation to confirm their operation. In addition, by changing the frequency of the generated pulses and inputting a signal corresponding to changes in engine speed to the object to be diagnosed, the operation of each component can be checked in a state close to its actual operation.

According to one feature of the present invention, when the instantaneous interruption detection means is selected by the switching means, when performing diagnosis, the input terminal of the apparatus of the invention is connected to the line subject to instantaneous interruption. and input the signal through the corresponding line. In this operation, when no signal is continuously input from the line to be diagnosed for a predetermined period, it is determined that there is a momentary power outage abnormality. Faults can be detected even when there is intermittent signal input. The above predetermined period is, for example, 10 m.
It can be about seconds.

In this case, when there is no input signal for a predetermined period of time after the start of measurement, the display means displays a message to that effect. For example, a momentary interruption of the target line is detected by lighting up a light emitting diode or by sounding a buzzer. Furthermore, when the device of the present invention is connected to a line that generates a pulse signal and the raw signal input means is selected by the switching means,
The input signal is input as is to the display means and displayed by the display means. For example, when a pulse signal is input, a display corresponding to the input pulse signal is performed. Therefore, when the display means is composed of a light emitting diode, it blinks at a frequency corresponding to the frequency of the input pulse signal. In this case, if the frequency of the input pulse signal is so high that the blinking state cannot be visually confirmed, the input signal may be input by switching to the first counting means having a frequency dividing function. The blinking frequency decreases and becomes visible to the naked eye. Furthermore, if the first counting means cannot discriminate, the signal may be input to the second counting means having an even greater frequency dividing function. As a result, even if a pulse signal with a higher frequency is input, it can be confirmed with the naked eye. Preferably, the degree of frequency division differs by about 10 times between the first counting means and the second counting means.

By visually monitoring the frequency of the input pulse in this way, it is determined whether a proper pulse signal is being input. In still another aspect of the present invention, the signal level of the input signal is determined, and according to the determined signal level, respective criteria for determining the appropriateness of the input signal are set, and the input signal is It is determined whether or not the input signal matches the criterion by comparing it with the criterion corresponding to the signal level, and if the state in which the input signal does not meet the criteria of the criterion continues for a predetermined period of time, the input signal is not appropriate. It is determined that In this case, the level of the input signal is not limited to one, but can be set to multiple levels, and when a certain signal is input, the target location is a location where a steady signal such as a DC signal occurs. These include lines connected to battery power, lines connected to converters for supplying power to various sensors, power supply lines or ground lines for control units, sensor input lines, sensor output lines, and the like. Then, the signal level is determined using a threshold depending on the input signal.

[0021] After level determination, it is determined whether the input signal is appropriate based on the determination criteria corresponding to each signal level. If the criterion is not satisfied for a predetermined period of time, a signal to that effect is generated. Still another feature is that in operating the diagnosis, first, the value of the input pulsation signal is measured at a predetermined period after the start of the operation, and based on the value (for example, a peak value), the suitability of the input pulsation signal is determined. A determination standard is set, and then, after a predetermined period of time has elapsed, the frequency of the input pulsation signal is measured according to the determination standard, and a reference frequency is set. Thereafter, if the frequency of the input pulsation signal is lower than the reference frequency, it is determined that the input pulsation signal is not appropriate. This makes it possible to change the determination not only for pulse signals but also for all pulsating signals such as alternating current signals and in accordance with the characteristics of the pulsation.

[0022] In this case, when setting the judgment criteria,
For example, after the start of operation, the input signal is sampled for a predetermined period of time, the values are averaged, a threshold value is established, and the frequency of this threshold value is counted by counting the period at which the input signal is cut off, and the frequency of that signal is compared with a reference frequency. is possible.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings in order to further clarify the structure and effects of the present invention. Referring to FIGS. 1-5, circuit diagrams of a failure detection apparatus according to one embodiment of the present invention are shown.

FIG. 1 shows a circuit diagram for performing a pulse check and a momentary interruption check. The input terminal 1 of this circuit is connected to a component to be checked or an appropriate portion of the wiring, so that a signal from the component or portion to be checked is inputted. On the other hand, this input terminal 1 is connected to a one-shot circuit 7 via a resistor 2, a diode 3, a one-shot circuit 4, an AND circuit 5, and a gate circuit 6. An inverter 8 is provided between the diode 3 and the AND circuit 5 in parallel with the one-shot circuit 4. Therefore, the output of the one-shot circuit 4 constitutes one input of the AND circuit 5, and the output of the inverter 8 constitutes the other input of the AND circuit 5. A gate circuit 9 is provided between the diode 3 and the one-shot circuit 7 in parallel with the circuit configuration for the AND circuit 5 and the gate circuit 6.

Further, between the diode 3 and the one-shot circuit 7, a frequency dividing terminal of 1/8, which is one terminal of the frequency dividing circuit 10, is provided in parallel with the gate circuit 9. is connected to the one-shot circuit 7 via the gate circuit 11, and the other terminal, the 1/64 frequency dividing terminal, is connected to the one-shot circuit 7 via the gate circuit 12.

One output terminal of the one-shot circuit 7 is
Via an inverter 13, it is connected to a light emitting diode 14 which is a visual display means and a buzzer 15 which is provided in parallel therewith and is an audible display means. Further, the inverted output terminal of the one-shot circuit 7 is connected to the light emitting diode 14 and the buzzer 15 via a D-type flip-flop circuit 16 as a holding circuit and an inverter 17.

Note that the light emitting diode 14 and the buzzer 15
has battery voltage (12 volts) applied to it. Figure 2
, the power supply circuit of the failure detection device of this example is shown. The input terminal of the power supply circuit in this example is connected to the battery 18, and is directly connected to this, and therefore 12
an output line 19 with a voltage of volts and a regulator 2
0 through 5 volts.

FIG. 3 shows a switch circuit that operates the failure detection device of this example, and by operating the switch SW1, one of the gate circuits 6, 9, 11, or 12 is selectively rendered conductive. . Note that the power input terminal of the one-shot circuit 7 is grounded via the push button switch SW2 by a line a5. Referring to Figure 4,
A circuit of a pulse current generator according to a specific configuration of the first invention of this example is shown.

The pulse generation circuit is basically composed of an IC, and is composed of an oscillation circuit 22 that generates a pulse signal, and three transistors 23, 24, and 25 connected to this oscillation circuit 22. It is composed of a current amplification circuit 26 that performs current amplification of a signal. The emitter of transistor 24 is connected by line 27 to the switch circuit shown in FIG. 5, and by switch SW3,
It is possible to select either the battery voltage VBAT, the adjustment voltage VCC, or an intermediate voltage thereof.

The oscillation circuit 22 is connected to a switch SW4 for turning on and off its operation, and is also connected to a variable resistor 28, and by changing the resistance value, the frequency of the generated pulses can be changed. Further, a light emitting diode 30 is provided between the transmitting circuit 22 and the power source via an inverter 29, and emits light in accordance with the frequency of the pulse.

The operation of the instantaneous failure device having the circuit configuration as described above will be explained. (1) Momentary interruption check Connect the input terminal of the power supply circuit shown in Figure 2 to the battery. When checking for a momentary interruption in the electrical system, switch SW1 is operated to connect line a1 so that gate circuit 6 becomes conductive.

The input terminal of the circuit of FIG. 1 is connected to the line in which the signal to be checked is generated. This line includes control system lines such as sensors, power supply ground lines,
It includes lines connecting the electronic control device and each electronic component controlled by the electronic control device. When an input terminal is connected to a line where a high-level "H" signal should be continuously generated, the input to the input terminal becomes low-level "L" for some reason, or the current drops more than a specified level. When this occurs, this input is input to the diode 3 and level-shifted to become a low level "L" signal, which is then input to the inverter 8. This signal is inverted by the inverter 8 and inputted to one terminal of the AND circuit 5 at a high level "H". The signal from the input terminal 1 is also input to the one-shot circuit 4 on the other hand. One shot circuit 4
In this case, the output does not change for a certain period of time after a fluctuation occurs in the signal. Then, after a certain period of time has elapsed, fluctuations corresponding to changes in the input signal at terminal A occur from the inverting output terminal. That is, after a certain period of time has passed since the input to the terminal A changed from high level "H" to low level "L", the signal from the inverted output terminal of the one-shot circuit 4 changes from low level "L" to high level "H". ”Instead,
At this point, the input conditions of the AND circuit 5 are satisfied.

The above-mentioned fixed period is determined by the capacitance of the capacitor 31 and the value of the resistor 32, and is set to 0.1 msec in this example. As a result, the output of the AND circuit 5 changes from a high level "H" to a low level "L", and this signal is input as a low level "L" to the terminal A of the one-shot circuit 7 via the gate circuit 6 which is in a conductive state. be done. This one-shot circuit 7 is configured to output a signal continuously for a certain period of time when a change in the signal occurs. This fixed period is determined by the values of the capacitor 33 and the resistor 34.

Therefore, the terminal A of the one-shot circuit 7
When the signal to the output terminal changes from high level "H" to low level "L" as described above, the output terminal outputs a high level "H" signal for a certain period of time. This signal is input to the light emitting diode 14 and the buzzer 15 via the inverter 13 as a low level "L" signal. This creates a voltage difference between the terminals of the light emitting diode 14 and the buzzer 15, causing the light emitting diode 14 to emit light and the buzzer 15 to sound for a certain period of time set by the values of the capacitor 32 and resistor 33 of the one-shot circuit.

In this case, the inverted output of the one-shot circuit 7, that is, the low level "L" signal is input to the preset terminal PR of the D-type flip-flop 16 for a certain period of time. As a result, a high level "H" signal is continuously output from the output terminal of the D-type flip-flop 16. This signal is passed through the inverter 17 to a low level “L”.
The signal is input to the light emitting diode 14 and the buzzer 15. As a result, the light emitting diode 14 and the buzzer 15 continue to emit light and sound beyond the above-mentioned fixed period.

However, it can be stopped by operating the switch SW2 and grounding the input of the one-shot circuit 7. In the above operation, if a signal is not generated continuously for 0.1 msec, the light emitting diode 14 and buzzer 15 will be activated as a failure indicator. The above operation was explained using a level signal as an example, but if the regularity of the pulse signal is disrupted, that is, if the pulse is missing, a signal stop state of 0.1 msec or more may occur. A similar display is performed in the case of

In this case, when a pulse signal is inputted periodically, the input conditions of the AND circuit 5 are not met, so the output of the AND circuit 5 continues to be at a high level "H".
The output of the one-shot circuit 7 is low level "L", the output of the D-type flip-flop 16 is also low level "L",
Therefore, the outputs of the inverters 13 and 17 become high level "H", and no display is performed by the light emitting diode 14 and the buzzer 15. (2) Pulse signal check When performing a pulse signal check, operate switch SW1 to select line a2, a3 or a4.

When line a2 is selected, gate circuit 9 becomes conductive. In this case, the signal input to the input terminal is rectified via the level shift diode 3, but the characteristics such as frequency remain unchanged in the one-shot circuit 7.
and is displayed by the light emitting diode 14 and buzzer 15. In this case, if the frequency is low, this blinking can be seen with the naked eye, but if the frequency is high, the pulse signal will be displayed as continuous light emission.

When the pulse signal is displayed as continuous light emission in this way, the gate circuit 11 or 12 may be made conductive by further operating the switch SW1. If the gate circuit 11 is selected to send a signal, the number of pulses will be one-eighth of the raw signal, making it possible to see the blinking state in the light emitting diode 14. Furthermore, if the blinking of the light emitting diode 14 cannot be seen even when the gate circuit 11 is made conductive, the gate circuit 12 may be further selected. In this case, the number of pulses is 1/64th of the raw signal. This makes the signal even easier to see. This level of frequency divider circuit 1 is suitable as an automotive failure instantaneous interruption device.
0, substantially all relevant pulse signals can be seen with the naked eye.

Therefore, the pulse signal of the line being checked can be easily confirmed. (3) Connect the pulse generation output terminal 36 to the input terminal of the component to be activated by the pulse signal. The switch SW4 is operated to cause the pulse generation circuit 22 to generate a pulse signal. This output signal can be current-amplified by transistors 23, 24, and 25 to operate a fuel injection valve or the like. This allows confirmation of the operation of the target component. Note that depending on the target component, it may not be preferable to apply the battery voltage VBAT as it is, but in this case, an appropriate voltage can be selected by operating the switch SW3.

Furthermore, the frequency of the pulse signal is controlled by the variable resistor 2.
8 can be changed appropriately, and the operation can be confirmed in a state close to the actual operation corresponding to the engine rotation speed. It is also possible to operate the pulse transmitter of FIG. 4 and simultaneously use the circuit of FIG. 1 to detect instantaneous interruptions or to check pulse signals at various locations.

Referring to FIG. 6, there is shown a functional block chart when the present invention is implemented using a microcomputer. In this example, the automotive failure diagnosis device includes a control unit 50 configured using a microcomputer, and the control unit 50 includes a level determining section 51 that determines the signal level, and a level determining section 51 that determines the level of the signal. It has an appropriateness determining section 52 that determines its appropriateness in reference to a standard. A signal from a line to be diagnosed is input to the control unit 50 via an input terminal. These signals include, for example:
A signal from the power line to the control unit 50,
Signal from the connection line to the battery power supply, signal from the engine speed sensor, signal from the engine coolant temperature sensor, signal from the air flow sensor, signal from the throttle opening sensor, signal from the ground line, crank angle sensor There are signals from, ignition signals, etc.

The control unit 50 is connected to a buzzer 53 and a lamp 54 as means for displaying the determination result. The level determination section 51 has thresholds corresponding to the levels of the various signals mentioned above. In this example,
Four signal levels of 12V, 5V, 0V, and 0.2V to 4.8V are determined. These levels correspond to the lines connected to the battery power supply, the power supply line for the control unit, the ground line, and the output line from the sensor, respectively. Further, the suitability determination section 52 has determination criteria 1 to 4 corresponding to these signal levels.

Referring to FIG. 7, a procedure for inputting a level signal to this device and determining its suitability will be described. So that one of the above various signals is input,
Connect the input terminal of the diagnostic device to the target part and turn on the measurement start switch (step S1). The signal is A
The signal is input to the level determination section 51 of the control unit 50 via the /D converter (step S2). Next, the control unit 50 determines the level of the input signal. In this case, if it is 9V or more, the signal level is determined to be 12V, if it is in the range of 4.8V to 5.3V, the signal level is determined to be 5V, and if it is in the range of 0 to 0.2V, it is determined to be 0V.
, 0.3V to 4.7V, it is determined to be the sensor output level (steps S1 to S6).

[0045] When about 0.3 seconds have elapsed, the suitability of the input signal is determined in accordance with the signal level of the input signal determined above. If the signal level is determined to be 12V,
It is determined whether the voltage has fallen below 9V for 10 m seconds (step S7). If it is determined that the signal level is 5V, it is determined whether the signal level remains 4.7V or less for 10 m seconds (step S8). If the signal level is determined to be 0V, the voltage will be 0.6 continuously for 10ms.
Determine whether the voltage has exceeded V (step S9)
. If it is determined that the signal level of the sensor output is 10
It is determined whether the voltage is outside the range of 0.2V to 4.8V for m seconds (step S10).

[0046] The judgment in steps S7 to S10 is YES.
In this case, it is determined that an abnormal signal has been input, and the buzzer sounds and the lamp is turned on (step S11). Also N
In the case of O, the process returns to step S2 and the above procedure is repeated. If all the determinations in steps S3 to S6 are NO, the buzzer is sounded and the lamp is turned on in the same way. Still another embodiment will be described with reference to FIGS. 8 and 9. The automotive failure diagnosis device of this example is configured using a microcomputer, similar to the previous example. In this example, the control unit 60 includes a detection section 61 that inputs a pulsation signal and detects its value, and a threshold value that processes the signal from this detection section and sets a threshold value corresponding to the input signal. a setting section 62; and a frequency detection section 63 that detects the frequency of the signal when the input signal is within the range of the threshold value set by the setting section 62.
, a determination section 64 that determines whether the detected frequency is within an appropriate range, and a buzzer 65 and a lamp 66 for displaying the determination results.

As shown in FIG. 8, when the measurement start switch is turned on, the control unit 60 inputs a signal for a predetermined period (approximately 0.3 seconds) via the A/D converter.
The value is detected and stored (step S1). next,
A threshold value is determined based on this value. This threshold value is obtained by dividing the sampling value of the input signal by the number of samplings (step S2). Next, the control unit 61 counts the signals that have fallen below the threshold value set in this manner and stores them as the reference frequency of the signals (step S3).
. Next, the frequency of the signal after the predetermined period has elapsed is measured, and it is determined whether the value is twice or more than the reference frequency (step S4). If this determination is YES, that is, if the frequency is twice or more than the reference frequency, the buzzer 65 and lamp 66 are continuously turned on to indicate this fact. Also, if the answer is NO, the buzzer 6
5 and lamp 66 are operated intermittently. This operation cycle is performed at a period corresponding to the frequency by appropriately dividing the signal, so that it can be visually observed. This confirms that the measurement operation has been completed and that the pulsation signal is normal.

In the devices of this example and the previous examples, in addition to the means for displaying the judgment result of the input signal from the object to be measured, there is also a means for detecting the engine rotation speed while the automobile fault diagnosis device is operating, that is, during the measurement operation. It is also equipped with a display that digitally displays this along with the above judgment results. Therefore, the pulsation signal can be observed in relation to the engine speed. According to this method, the determination criteria can be changed for all pulsating signals such as not only pulse signals but also alternating current signals, depending on the characteristics of the pulsation, and appropriate determination can be made in response to the signal characteristics.

Furthermore, the level signal diagnosis and the pulsation signal diagnosis can be performed selectively as appropriate by operating a switch.

[0050]

As described above, according to the present invention, instantaneous interruption of level signals and pulsating signals can be properly performed. Also,
Since appropriate criteria are provided for each signal, it is possible to easily and accurately detect vehicle failures with a simple configuration.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram for signal detection according to an embodiment of the present invention;

FIG. 2 is a power supply circuit diagram according to an embodiment of the present invention;

[Figure 3
】Circuit diagram of the switch used in the circuit of Figure 1,

[Figure 4] Circuit diagram for pulse current generation,

FIG. 5 is a circuit diagram of a switch used in the pulse current generation circuit of FIG. 4;

FIG. 6 is a block diagram of an apparatus according to another embodiment of the present invention;

FIG. 7 is a flowchart of diagnostic operation in the embodiment of FIG. 6;

FIG. 8 is a block diagram of a device according to still another embodiment of the present invention;

FIG. 9 is a flowchart of diagnostic operation in the embodiment of FIG. 8;

[Explanation of symbols]

1 input terminal, 2 resistor, 3 diode, 4
One-shot circuit, 5 AND circuit, 6 Gate circuit, 8 Inverter, 10 Frequency divider circuit, 14
Light emitting diode, 23 transistor, 50 control unit 60 control unit.

Claims (10)

[Claims] 1. Instantaneous interruption detection means for detecting that no signal is continuously input for a predetermined period; raw signal input means for accepting pulse input signals as they are; a first counting means that outputs a signal every time a signal is input; a second counting means that outputs a signal every time a predetermined number of signals greater than the predetermined number counted by the first counting means is input; and a switching means for selectively connecting the instantaneous interruption detection means, the raw signal input means, the first counting means, and the second counting means to the display means. A fault diagnosis device for automobiles. 2. A pulse generating means for generating a pulse signal, a current amplifying means for amplifying the current of the pulse signal from the pulse generating means, and supplying power to the current amplifying means at at least two different voltage values. and a voltage changing means that changes the connection state between the current amplifying means and the power supply means to change the voltage supplied to the current amplifying means, and a voltage changing means that changes the voltage supplied to the current amplifying means. A fault diagnosis device for an automobile, characterized in that the device can be changed according to the conditions. 3. Level signal determining means for determining the level of a level signal; standard setting means for providing a signal determination standard according to the level determined by the signal level determining means; and an input signal to the standard setting means. 1. A fault diagnosis device for an automobile, comprising: a signal generating means for emitting a signal when a determination criterion is exceeded for a predetermined period of time. 4. A value detection means for detecting a maximum value of a pulsation signal, a reference setting means for setting a criterion for determining the pulsation signal based on the value, and a pulsation of the input signal is a reference set by the reference setting means. Accordingly, there is provided a failure diagnosis device for an automobile, comprising frequency storage means for measuring and storing the frequency of a signal, and signal generation means for emitting a signal when the frequency of the input signal falls below a predetermined value. 5. A first display means for visually displaying the signal from the signal generating means; and a first display means for visually displaying the signal from the signal generating means; and a first display means for visually displaying the signal from the signal generating means; A second display that visually displays the signal
A fault diagnosis device for an automobile, characterized in that it is equipped with a display means. 6. A fault diagnosis device for an automobile according to claim 5, further comprising means for generating a sound corresponding to a signal from the signal generating means in place of the first display means. 7. Determining the signal level of an input signal, and setting respective determination criteria for determining the appropriateness of the input signal according to the determined signal level, wherein the input signal is set at the signal level. Determining whether or not the input signal conforms to the criteria in reference to the corresponding determination criteria, and determining that the input signal is inappropriate if a state in which the input signal does not meet the criteria of the determination criteria continues for a predetermined period of time. An automotive failure diagnosis method characterized by: 8. Measure the value of the input pulsation signal, set a criterion for determining the suitability of the input pulsation signal based on the measured value, and after a predetermined period has elapsed, adjust the input pulsation signal according to the criterion. A fault diagnosis method for an automobile, characterized in that a reference frequency is set by measuring the frequency of the input pulsation signal, and thereafter, when the frequency of the input pulsation signal becomes lower than the reference frequency, it is determined that the input pulsation signal is inappropriate. 9. In claim 8, when the frequency of the input pulsation signal measured according to the criterion exceeds the reference frequency after a predetermined period when the engine speed is within a predetermined range, the input pulsation signal is A fault diagnosis method for an automobile characterized by determining that the vehicle is inappropriate. 10. Level signal determining means for determining the level of a level signal; standard setting means for providing a signal determination standard according to the level determined by the signal level determining means; and an input signal to the standard setting means. a first signal generation means that generates a signal when the signal exceeds a determination criterion for a predetermined period of time; a pulsation signal value detection means; and a reference setting means that sets a determination criterion for the pulsation signal based on the value. frequency storage means for measuring and storing the frequency of the input signal according to a reference set by the reference setting means; and a second frequency storage means for emitting a signal when the frequency of the input signal exceeds a predetermined value. A failure diagnosis device for an automobile, comprising a signal generating means and a switching means for selectively switching between the first signal generating means and the second signal generating means.