JPS5924270A - Apparatus for diagnosis trouble of internal combustion engine - Google Patents

Abstract

PURPOSE:To rapidly perform diagnosis prior to running and during repairing inspection, by providing two kinds of diagnostic modes different in diagnostic times so as to make it possible to carry out the diagnosis of trouble in accordance with a diagnosis utilizing situation. CONSTITUTION:In the case of a longtime diagnosis mode, an AND gate 3 is opened by the level signal H of a constant voltage source 7 and the pulse of an oscillation circuit 1 is counted by a counter 14 to set a long diagnostic time. The decision of all items are performed in a trouble decision circuit 19 and, when either one of items develops trouble, an AND gate 16 is opened to lighten a warning lamp 22 to give an alarm and a trouble code display lamp 25 exhibits a trouble place. When a connector 8 is connected to earth the constant voltage source 7, an AND gate 4 is opened and a short diagnostic time is set by the pulse of an oscillation circuit 2. When an OK signal of all items is outputted from the trouble decision circuit 19, a signal is outputted from an AND gate 17 to turn the lamp 22 ON and OFF and OK display is outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention monitors the operating status of a control system that performs exhaust gas purification, air-fuel ratio control, etc. in a vehicle internal combustion engine, and detects whether or not there are any failures in various sensors, switches, solenoids, etc. This invention relates to a fault diagnosis device that performs self-diagnosis, and specifically relates to one in which diagnosis time is divided into two systems.

1- In recent years, internal combustion engines for vehicles have been equipped with various control systems to purify exhaust gas and improve fuel efficiency and output, and the engine itself is now operating according to instructions from the control systems. . Therefore, failures in various control systems immediately disturb the smooth operation of the internal combustion engine, and for this reason, it is essential to always perform failure diagnosis of the control system on your own.

Therefore, various diagnostic devices have been proposed in the past.
One of them is, for example, Japanese Unexamined Patent Publication No. 56-34540, in which the entire internal combustion engine including the control system is comprehensively diagnosed. However, since there is only one type of diagnosis mode, it always takes a certain amount of time to judge all items under all conditions. Here, it is desirable to carry out the diagnosis when the engine has left idle-link operation after starting and is in a predetermined load operation state. Diagnosis will only be performed after the vehicle has been driven.

By the way, when actually diagnosing the operating condition of the internal combustion engine (2-), as mentioned above, it is necessary to spend sufficient time while the vehicle is running.
Although it is of course necessary to perform a diagnosis using GJ, it is preferable if the diagnosis can be performed in a short time before driving the vehicle or during periodic inspections, as this will further enhance the effectiveness of the diagnosis.

In view of these circumstances, the present invention aims to provide a fault diagnosis device for an internal combustion engine that has two types of diagnosis modes with different diagnosis times and is capable of performing an appropriate diagnosis depending on the usage status of the fault diagnosis. purpose.

For this purpose, the device according to the present invention selectively switches between two types of diagnostic modes with different diagnostic times by a simple operation of whether or not the earth is connected, and cumulatively sets the diagnostic time at or above the set engine speed. When displaying the diagnosis results, in the long-term diagnosis mode, the warning lamp is turned off when the condition is normal, whereas in the short-time diagnosis mode, the warning lamp flashes and an OK display is displayed when the condition is normal.
It is characterized by being able to make the diagnosis results more clearly recognized.

Embodiments of the present invention will be specifically described below with reference to the drawings. In FIG. 1, reference numeral 1 is an oscillation circuit that has long pulse intervals and sets a long diagnosis time, and 2 is an oscillation circuit that has short pulse intervals and sets a short diagnosis time.These oscillation circuits 1゜2 is connected to AND gate 6 via AND gates 3 and 4 and OR gate 5. code 7
is a constant voltage source, and in the case of long-term diagnosis mode (hereinafter referred to as normal mode), -1 level of this constant voltage source 7 causes -
[One of the AND gates 3 mentioned above is opened, and in the case of short-time diagnosis mode (hereinafter referred to as check mode), the constant voltage source 7 is grounded by connecting the connector 8, and the other AND gate mentioned above is opened by the L level in this case. It is designed to open 4.

Reference numeral 9 is an ignition pulse input terminal, and a signal from this terminal 9 is input to an engine rotation speed detection circuit 10. As shown in FIG. 2, the circuit 10 inputs an ignition pulse signal to a frequency-voltage converter 12 via a waveform shaping circuit 11, shapes a voltage according to the frequency of the pulse, and inputs it to an operational amplifier 13. . On the other hand, a constant voltage is applied to the operational amplifier 13, and by comparison with this constant voltage, the output of the operational amplifier 13 becomes 1 level only when the engine rotation speed is higher than the set engine speed, and the AND gate 6 is opened. There is.

Thus, the pulses of the oscillation circuit 1 or 2 are cumulatively counted by the counter 14 when the engine speed is equal to or higher than the set engine speed.
A long diagnosis time of 0 minutes is set, but in the case of the check mode, a short diagnosis time of, for example, 1 minute is set by the oscillation circuit 2.

When the counter 14 finishes counting to set these diagnostic times, the output signal of the counter 14 holds the output of the flip-flop 15 at H level, and the output of the flip-flop 15 is connected to the AND gate 16.17.
and is input to the trouble code generation circuit 18. AND
The gate 16 opens in response to an L level signal from the failure determination circuit 19 in the case of a failure, turns on the transistor 21 via the OR gate 20, and lights up the warning lamp 22. The AND gate 17 is connected to the constant voltage source 7 and opens with an L level signal in the check mode, and when an H level signal indicating that all items are OK from the failure judgment 5 circuit 19 is input. A pulse signal synchronized with the oscillation circuit 23 is output, thereby causing the warning lamp 22 to blink. Failure determination circuit 1
The output of 9 is also input to the trouble code generation circuit 18,
By turning on the transistor 24, the trouble code display lamp 25 at each failure location flashes in a mode corresponding to the failure location.

For example, in the case of a water temperature sensor as the failure determination circuit 19, the operation signal of the sensor is taken out from the terminal 26, and this signal is connected to the comparator 21 to which a voltage corresponding to the minimum value of the operation signal is applied. A voltage corresponding to the maximum value is applied to the comparator 28. Therefore, in the normal operating state, both comparators 2
Both outputs of 7.28 become H level, but in the case of a failure, one of them becomes L level, and from this it is determined whether there is a failure. And both comparators 27.
When the outputs of 28 are both at H level, the flip-flop 29
The output of is held at 1-level, and the judgment results of other items are inputted to AND gate 306- in the same way, so that AND is performed only when all items are OK.
The output of gate 30 becomes I'' level. Further, the results for each item are provided to the trouble code generation circuit 18.

With this configuration, in the case of normal mode diagnosis, the AND gate 3 is opened by the H level signal from the constant voltage source 7. Therefore, when the engine rotation speed is higher than the set engine speed, the AND gate 6 is opened by the H level signal from the circuit 10, and the pulses of the oscillation circuit 1 are counted by the counter 14, thereby cumulatively setting a long diagnosis time. When it reaches A
The ND gate 16 and trouble code generation circuit 18 are maintained in an operating state. On the other hand, the failure judgment circuit 19 judges all items, and when all items are OK and an H level signal is output, the AND gate 16 is closed and the warning lamp 22 is turned off. On the other hand, if any item fails, AND'7''-t16 is activated by the Lebel signal.
opens and the warning lamp 22 lights up to issue an alarm, and at the same time, the trouble code display lamp 25 at the failure location blinks in accordance with the mode corresponding to the failure location to display the failure location.

Next, when the connector 8 is connected and the constant voltage source 7 is grounded, the mode is switched to the check mode and the AND gate 4 is opened. Therefore, under the same conditions as above, a short diagnostic time is set by counting the pulses of the oscillation circuit 2 with the counter 14,
When this diagnostic time is reached, the AND gate 16 is opened only in this mode and the AND gate 17 and the trouble code generation circuit 18 are kept in the operating state. In this manner, when the failure determination circuit 19 outputs a 1-level signal indicating that all items are OK, a pulse signal synchronized with the oscillation circuit 23 is output from the AND gate 17, the warning lamp 22 blinks, and an OK display is made. On the other hand, when an L level signal is output in the case of a failure, the AND signal is output as in the normal mode.
The output of the gate 16 becomes 1'' level, and the warning lamp 22 lights up to give an alarm, and the trouble code display lamp 25 blinks in response to a signal corresponding to the failure location to indicate the failure location.

Referring to FIG. 4, an embodiment in which the above-mentioned fault diagnosis operation is performed by a microcomputer will be described. Diagnosis signals for each item and signals for each mode are input to the microcomputer 31. Therefore, in the microcomputer 31, as shown in FIG. iJ: The program is executed according to the flowchart, and the warning lamp 22 is turned off, turned on, and flashed, and the same operation as described above is performed.

As is clear from the above description, according to the present invention, a short-time diagnosis mode is added in addition to the long-time diagnosis mode, and by selecting these modes, failure diagnosis can be performed according to the usage status of the diagnosis. Diagnosis can be performed quickly, especially before driving and during maintenance inspections. Also,
Diagnosis results obtained while driving in normal mode can be reconfirmed in check mode, which helps prevent erroneous judgments. If all items are OK in the check mode, the warning lamp 22 flashes to indicate OK, so the diagnostic effect is further enhanced. Since the diagnosis time is cumulatively set at the engine rotation speed or higher, the diagnosis can be performed in an appropriate engine operating state.

[Brief explanation of the drawing]

9- Fig. 1 is a circuit diagram showing a first embodiment of the device according to the present invention, Fig. 2 is a circuit diagram showing an engine rotation speed detection circuit, Fig. 3 is a circuit diagram showing a failure determination circuit, and Fig. 4 5 is a circuit diagram showing a second embodiment of the apparatus according to the present invention, and FIG. 5 is a diagram showing a flowchart. 1, 2, 23... oscillation circuit, 3, 4, 6,
16.17゜30...AND gate, 5.20...
OR gate, 8...connector, 9.26...terminal,
10... Engine speed detection circuit, 11... Waveform shaping circuit, 12... Frequency-voltage converter, 13... Operational amplifier, 14... Counter, 15.29... Flip 70 tube , 18...Trouble code generation circuit, 19.
...Failure determination circuit, 21.24...Transistor, 2
2...Warning lamp, 25...Trouble code display lamp, 27, 28...Comparator, 31.
...Microcomputer. 10-

Claims (1)

[Claims] It has two types of diagnosis modes with different diagnosis times that can be switched, and by selecting one of these modes, the diagnosis time is cumulatively set at the engine set rotation speed or more, and as a result of the failure determination, there is a failure. If the condition is normal, the warning lamp will turn on in any of the above modes and the location of the failure will be displayed. If the condition is normal, the warning lamp will turn off in the long-term diagnosis mode, but in the short-time diagnosis mode, the warning lamp will be turned off. A failure diagnosis device for an internal combustion engine, characterized in that the lamp is configured to blink.