JPH0440538B2 - - Google Patents

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a device having a failure diagnosis function for an intake pressure detector, which is a component of an internal combustion engine control device, and particularly relates to an internal combustion engine control device using a microcomputer. The present invention relates to a device that can perform failure diagnosis and countermeasures for the device using simple means.

[Prior art]

A characteristic feature of the configuration of a control device using a microcomputer is processing using a reset signal for initializing the microcomputer. A power-on reset is performed to initialize the microcomputer or its peripheral elements at the initial stage when power is applied to the control device by a key switch. In addition, even if the key switch is left on, if an excessive load causes the battery voltage to drop abnormally at the moment the starter switch is turned on, a reset is generated when the battery voltage recovers to initialize the microcomputer, etc. There is a need to.

By the way, as shown in Japanese Patent Laid-Open No. 101244/1983, there is a conventional method for diagnosing failure of an intake pressure detector, in which different judgment conditions are set depending on the operating state during engine operation. It's quite complicated. In addition, one of the simplest conventional methods is to perform a failure diagnosis when the internal combustion engine is stopped, such as immediately after the key switch is turned on. This is because the judgment conditions for failure diagnosis become complicated during operation of the internal combustion engine, and it is undesirable to increase the proportion of the judgment program included in the control program.

However, there are other problems with the method of performing fault diagnosis when the internal combustion engine is stopped. That is, depending on the internal combustion engine, there is a high probability that an instantaneous reset will occur due to the aforementioned starter switch. In that case, the information on the diagnostic results carried out during the stop after the key switch is turned on will be initialized due to the decrease in battery voltage caused by the starter start.

[Purpose of the invention]

Therefore, in the present invention, the above-mentioned engine starting instantaneous control means is implemented by performing a failure diagnosis under the condition that the engine speed is equal to or less than the first set value, not when the internal combustion engine is stopped, but when the engine is started. This is an attempt to eliminate the disadvantages that the initialization (resetting) of the conventional method has.

In addition, regarding the content of control processing at the time of failure detection,
Conventionally, when a failure of the intake pressure detector is detected, the status of other internal combustion engines is detected. For example, a method is used in which an approximate value of the intake pressure is predicted based on information obtained from a gear position detector and a rotation detector, and the predicted value is used as data for calculating the control amount.

However, such means already presuppose an advanced centralized control control device, and are relatively low-level or local control systems that have only a rotation detector and an intake pressure detector as internal combustion engine status detectors. This is not possible with equipment. Furthermore, even in advanced centralized control, as microcomputer systems are becoming more and more integrated into single chips, there is still a limit to the capacity of the program memo memory (ROM), and the control items required are becoming more diverse and complex. Fail-safe systems must be implemented using more compact means, and in this sense, conventional methods need to be replaced by simpler methods. Furthermore, in the conventional method as described above, even if the intake pressure sensor fails, the driving performance of the internal combustion engine is not impaired, and unless the engine has a failure monitoring function, it is difficult to notify the general driver of the occurrence of a failure. I can't.

Therefore, according to the present invention, it can be realized even in a relatively low-grade control device by simpler means, and moreover, it is possible to directly notify general users of a malfunction through a decrease in operating performance, or to contact the nearest repair company. The aim is to provide equipment that can be transported to the factory.

〔Example〕

Next, a specific embodiment according to the present invention is shown in FIG. The rotation detector 100 is a rotating roller 10 installed on a shaft 107 that interlocks with a camshaft of an internal combustion engine 101.
8 and 109, and electromagnetic pickups 110 and 110 installed near the rotating rotor. The rotating rotor 108 and the electromagnetic pickup 110 provide a reference position signal a for the process of the internal combustion engine 101, and the rotating rotor 109
and an electromagnetic pickup 111 provide information signals b of the angle and rotational speed of the crankshaft of the internal combustion engine 101. Furthermore, an intake pressure detector 103 is installed in the intake pipe 102 of the internal combustion engine 101, and provides intake pipe pressure by means of a DC voltage c proportional to the pressure inside the pipe.

The internal combustion engine control device 115 includes a one-chip microcomputer 120 having a built-in timer function, serial function, etc., which receives the rotation reference position signal a, shapes it into a rectangular wave, and gives the timing of the rotation reference position to the microcomputer 120. Circuit 116, similarly the waveform shaping circuit 11 for angle signal b
7. Analog/digital (A/
D) Consists of a converter 118, an output stage amplifier 121 for the ignition signal output e, and a power supply section 119.

Here, the power supply section 119 is supplied with power via the battery 114 and the key switch 113, and generates a stabilized power supply V _CC in the control device 115 and a reset signal d for the microcomputer 120. Here, the reset signal d is generated immediately after the battery power supply V _B is turned on, and when the battery voltage V _B is extremely low and the stability of the power supply V _CC cannot be maintained, and initializes the computer 20. Do this.

The main work of the microcomputer 120 is to
Optimal control variables such as ignition timing θig are calculated from the rotational speed Ne of the internal combustion engine obtained from the angle signal waveform shaping circuit 117 and the intake pressure _VB obtained from the A/D converter 118, and the ignition timing θig is used as a reference. This is realized in the ignition output signal e based on the angle timing given from the signal waveform shaping circuit 116 and the angle signal waveform shaping circuit 117. The output f of the output stage 121 ignites the spark plug 104 of the corresponding cylinder via the ignition coil 106 and the distributor 105 which is interlocked with the camshaft.

The configuration of the key switch 113 is a battery power supply.
OFF state where the entire system is stopped using V _B as a common terminal,
It consists of three states: a key switch ON state for electrical standby, and a starter ON state for starting the starter 112.

Next, a method for diagnosing a failure of an intake pressure detector according to the present invention will be explained with reference to a time chart shown in FIG. FIG. 2a shows the voltage of the power supply V _BO of the control device 115, which increases to the battery voltage V _B by turning on the key switch and maintains a constant value V _B.
Next, the voltage decreases dramatically at the moment the starter starts, and as the internal combustion engine begins to rotate, the voltage gradually recovers to the original _VB . At this time, the microcomputer 120
As shown in FIG. 2b, the reset signal d corresponding to the reset signal d is generated both when the key switch is turned on and when the voltage of the power supply V _BO decreases sharply due to starting of the starter. However, it is assumed that the low level (OV) of the reset signal d indicates that the reset is valid, and the high level (V _CC ) indicates that the reset is released. The generation of such a reset signal at the time of starting the starter occurs because the starter consumes an excessive amount of current at the instant of starting, and is generally unavoidable considering temperature conditions and the like.

Therefore, in the present invention, when a reset signal is generated regardless of the cause, immediately after the reset signal is generated, the intake pressure is A/D converted and the result Pbo is stored. After that, when the internal combustion engine starts to start and the angle signal b is generated as shown in Figure 2 c, the time interval To between the first two pulses is measured, and this To is used as data in Figure 2 e. The instantaneous rotational speed Neo is calculated and stored at the timing shown. And finally, as shown in Figure 2 f,
Immediately after calculating Neo, the intake pressure detector 103
Executes failure determination. The judgment method is the pressure value mentioned above.
Regarding Pbo and the rotation speed Neo, {Neo＜Ne _LMT }and{Pbo＜Pb _L or
If Pb _H <Pbo}, it is determined that the intake pressure detector is malfunctioning, and an intake pressure detector failure flag F is set. However, with regard to Ne _LMT , Pb _L , and Pb _H , by setting No _LMT sufficiently small, when the intake pressure detector 103 is normal, the target internal combustion engine will always have a constant value when Neo < Ne _LMT . is always Pb _L <
The value shall be set so that Pbo< _PbH .

In the method described above, the A/D conversions 203 and 204 of the intake pressure are performed at both timings, immediately after the reset 201 at the time of the key switch and immediately after the reset 202 at the instant the starter is started.
Even if the result of the former A/D conversion 203 is erased by the latter reset 202, the result of the latter A/D conversion 204 can be used for fault diagnosis. However, since the latter A/D conversion 204 is performed when the internal combustion engine starts to rotate after the starter is started, in the present invention, the latter A/D conversion 204 is performed especially immediately after the starter starts, that is, the latter A/D conversion
Instantaneous rotation speed Neo near where conversion 204 is performed
By setting the judgment condition to be sufficiently low,
This avoids the risk of misjudgment. This is because when Neo is sufficiently low, the simple condition Pbo < Pb _L or Pb _H < Pbo can be used as a failure judgment condition for the intake pressure detector. For Ne _LMT , it is practical to adopt a value of about 30 to 50% of the idle rotation speed of the internal combustion engine.

Therefore, the present invention is performed in a starter switch,
By performing a failure diagnosis of the intake pressure detector 103 when the internal combustion engine has started rotating,
By starting the starter, the microcomputer 12
This provides a simple and effective method for diagnosing the fault of the intake pressure detector, which is effective even in most internal combustion engine control devices where the sensor is initialized when reset to 0. It is also extremely effective in the sense that it is a flexible method that can be used even in relatively low-grade systems.

Next, the process to be reflected in the control after it is determined that the intake pressure detector 103 is malfunctioning, that is, after the flag F is set, will be explained using FIG. FIG. 3a shows an example of a temporal change in the rotational speed of the internal combustion engine when it is determined that the intake pressure detector 103 is malfunctioning at the time of starting the starter.
First, (b) and (c) are two examples showing the contents of ignition control in that case.

After the starter starts, if the failure flag F is set and the rotational speed Ne is below the second constant rotational speed Ne _F , the intake pressure detector output A/D conversion value is ignored, and Pb = Pb _F Optimal advance angle θig as (constant value)
= f(Ne, Pb _F ) and perform ignition control accordingly. At this time, the value of Pb = Pb _F is the rotation speed Ne
The value is set so that it can be sufficiently driven at Ne _F or less. If the rotational speed further increases and becomes larger due to Ne _F , in the first example (Fig. 3b), the output of the internal combustion engine is reduced to zero by stopping the ignition control, and in the second example In (Fig. 3c), the ignition is controlled at the advance angle θigO, that is, near the top dead center of the internal combustion engine, and by drastically reducing the output of the internal combustion engine, the abnormality of the internal combustion engine control device 115 is corrected and its operating performance is improved. Inform the driver directly about the lowering.

In the conventional method, if the intake pressure detector fails, a substitute intake pressure Pb is determined based on information from another detector, such as a gear position detector.
Since the optimum control amount such as advance angle was calculated and controlled based on this, the driving performance did not deteriorate significantly, and the failure of the intake pressure detector was not caused particularly by the driver's concern through the deterioration of driving performance. This required a more advanced configuration such as a monitor function.

However, in the control processing method in the event of an intake pressure detector failure according to the present invention, a relatively low-grade internal combustion engine that only has a revolution detector and an intake pressure detector as internal combustion engine status detectors, or does not have a failure monitoring function, is used. In engine control systems as well, it is possible to directly notify the driver of a malfunction in the intake pressure detector through a drop in driving performance, and to achieve the minimum driving performance that allows transportation to a repair shop, and its range of applications is wide.

Flowcharts of programs to be run within the microcomputer in order to carry out the embodiment of the present invention described above are shown in FIGS.

FIGS. 4a, b, and c are flowcharts of failure diagnosis, and FIGS. 5a and 5b are flowcharts of control processing, respectively. The fault diagnosis program includes reset processing (Fig. 4a), angle signal interrupt processing (Fig. 4b),
judgment process (Fig. 4c), and these are the second
A/D conversion processing 203 and 204 in the figure, respectively;
This corresponds to the rotation speed calculation process 205 and the failure determination process 206.

First, the reset process shown in FIG. 4a is performed during the initialization process when the reset signal d is applied to the microcomputer 120, and performs A/D conversion of the intake pressure to reset the intake pressure immediately after the reset signal is applied. atmospheric pressure
Two processes are performed: obtaining Pbo, and initializing a variable n for determining whether several angle signal pulses have been input after the reset signal is released.

The angle processing shown in Fig. 4b is executed in the interrupt processing program based on the angle signal, and the number of pulses n is increased by 1 and counted, and when n=2, the immediately preceding pulse is The instantaneous rotational speed Neo immediately after the starter starts is calculated based on the interval measurement result To.

Further, the determination process shown in FIG. 4c is performed in the program base process immediately after the reset process and angle interrupt process are completed, and {Neo<Ne _LMT } and {Pbo<Pb _L or Pb _H <Pbo} The intake pressure detector failure flag F is set only when the following is true; otherwise, the flag F is cleared. Here, Neo＞
In Ne _LMT , flag F is cleared, but Neo > Ne _LMT occurs when a reset signal is generated due to some malfunction while the internal combustion engine is sufficiently rotating after starting the starter. In such cases, the judgment is invalidated.

Next, the control processing after the failure diagnosis is completed includes the advance angle calculation processing shown in FIG. 5d and the control processing shown in FIG. 5b. What is shown here is sometimes Ne＞
This concerns a method of setting the advance angle to θig0 in the case of Ne _F. The advance angle calculation in Figure 5a is executed in the base processing of the program, and when flag F is cleared, the current rotational speed Ne,
Optimal advance angle Pb = f determined from intake pressure Pb
(Ne, Pb) is calculated, and when the flag F is set, the value of the rotational speed Ne is used. If Ne< _Ne Based on _F , θig=f(Ne,
Pb _F ) is calculated, and when Ne>Ne _F , θig=0. The control process shown in FIG.
The advance angle θig calculated in the angle calculation process described above is realized by timing control using a programmable timer function in 0.

〔Effect of the invention〕

As described above, in the present invention, since the failure diagnosis of the intake pressure detector is performed in the low rotation range when starting the engine, the pressure inside the intake pipe is considered to be approximately in the atmospheric pressure range, and therefore The failure judgment condition of the detector can be set to a constant value, and the failure diagnosis process can be performed easily. In addition, in the case of a digital device that uses a microcomputer as an engine control means, the computer is initialized every time the power supply voltage drops, but since the fault diagnosis processing of the present invention is performed at the time of starting the engine, the voltage drop at the moment of starting It will be executed immediately after that, and it will be possible to sufficiently avoid erasing the failure diagnosis results. Furthermore, relatively low-grade internal combustion engine control devices that only have a rotation detector and an intake pressure detector as internal combustion engine status detectors, or do not have a failure monitoring function, can detect malfunctions of the intake pressure detector during operation. This has the excellent effect of notifying the driver directly of the deterioration in performance and achieving the minimum level of driving performance that will allow the driver to travel to a repair shop.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the device of the present invention;
Fig. 2 is a timing chart showing the fault diagnosis process according to the present invention, Fig. 3 is an explanatory diagram showing the engine control process during fault diagnosis according to the present invention, and Figs. 4 and 5 are flow charts used to explain the operation of the present invention. be. 100... Rotation detector, 101... Internal combustion engine,
103...Intake pressure detector, 104...Spark plug, 115...Control device, 119...Power supply unit, 1
20...Microcomputer.

Claims (1)

[Claims] 1. Receiving signals from a group of detectors installed in the internal combustion engine that detect the operating state of the internal combustion engine, including at least a rotation detector and an intake pressure detector, and calculating the optimum control amount of the internal combustion engine based on the signals, Furthermore, the internal combustion engine control device is provided with a control means for controlling the internal combustion engine based on the optimum control amount, wherein when the engine is started, the engine speed is equal to or less than a first set value lower than the idling speed. and determining means for determining that the detector is normal when the output of the intake pressure detector is within a predetermined range near atmospheric pressure, and determining that the detector is malfunctioning when it is not within the range, and the control means: A predetermined fixed value is set instead of the output of the intake pressure detector while the engine speed is below a second set value higher than the first set value when the determination means determines that the intake pressure detector is malfunctioning. An internal combustion engine control device, comprising means for calculating an optimal control amount for the internal combustion engine using the value and for reducing the operating performance of the internal combustion engine when the value exceeds the second set value.