JPH02112646A - Misfire detector for multicylinder internal combustion engine - Google Patents

Abstract

PURPOSE:To detect a misfire cylinder so accurately without entailing any increase in operational load by detecting the misfire cylinder on the basis of a variation portion of momentary engine speed in a specified turning angle position at each cylinder of a multicylinder internal combustion engine. CONSTITUTION:Plural numbers of angular positions per rotation of a multicylinder internal combustion engine A is detected by a unit signal generating means B. On the basis of an angular position interval detected, momentary engine speed in a specific rotational position at each cylinder is detected by an engine speed detecting means C. Then, on the basis of a variation portion of this detected momentary engine speed, an abnormal cylinder is detected by an abnormal cylinder detecting means D. In brief, a misfire cylinder is detected on the basis of the variation portion of the momentary engine speed in the specific turning angle position at each cylinder of the multicylinder internal combustion engine. With this constitution, the misfire cylinder is accurately detected without entailing any increase in operational load.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is a multi-cylinder internal combustion engine that automatically detects a cylinder in which ignition does not occur normally (misfire). In this method, the instantaneous rotational speed between each angular position is detected from the angular position interval detected by a unit signal generating means that detects multiple angular positions per rotation of a multi-cylinder internal combustion engine, and the minimum value of each cylinder is determined from among the angular position intervals. It is known that a misfiring cylinder is detected by determining at least one of the maximum value and the maximum value, and detecting a misfiring cylinder based on the variation between each cylinder.
180.31).

[Problem to be solved by the invention]

However, in the conventional system described above, in order to determine at least one of the minimum and maximum values of the instantaneous rotational speed of each cylinder, it is necessary to constantly calculate the variation in the instantaneous rotational speed between each angular position. , there is a problem that the calculation load becomes large and it is not practical.

In addition, in order to reduce the calculation load, it is possible to detect the average rotational speed of each cylinder from the angular interval between the top dead center of each cylinder, and detect abnormal cylinders from the change in this average rotational speed. Since the average rotational speed in a wide angular interval between the top dead center of each cylinder is detected, the variation in rotational speed between a cylinder that misfires and a cylinder that does not misfire is reduced, making it possible to accurately identify the cylinder that misfires. The problem is that I can't.

Therefore, an object of the present invention is to accurately detect a misfiring cylinder without increasing the calculation load.

[Means to solve the problem]

Therefore, as shown in FIG. 1, the present invention includes a unit signal generating means for detecting a plurality of angular positions per rotation of a multi-cylinder internal combustion engine, and a specific angular position interval detected by the unit signal generating means for detecting a specific position of each cylinder. A multi-purpose cylinder comprising a rotation speed detection means for detecting an instantaneous rotation speed at a rotation position, and an abnormal cylinder detection means for detecting an abnormal cylinder based on the variation in the instantaneous rotation speed at a specific rotation position of each cylinder detected by the rotation speed detection means. A misfire detection device for a cylinder internal combustion engine is provided.

[Effect]

As a result, the unit signal generating means detects a plurality of angular positions per rotation of the multi-cylinder internal combustion engine, and the rotational speed detecting means detects the instantaneous timing of a specific rotational position of each cylinder based on the angular position interval detected by the unit signal generating means. Detects the rotation speed,
An abnormal cylinder is detected by the abnormal cylinder detection means based on the variation in the instantaneous rotation speed at a specific rotational position of each cylinder detected by the rotation speed detection means.

〔Example〕

The misfiring cylinder detection device for a multi-cylinder internal combustion engine according to the present invention has a configuration as shown in FIG. 2 in order to achieve the above object. A unit signal generating means 1 that generates a plurality of unit signal pulses per revolution of the crankshaft, and a reference signal generating means 2 that generates one reference signal pulse per revolution of the camshaft, which rotates once every two revolutions of the engine. and a microcomputer 3 including misfiring cylinder discriminating means for measuring the pulse period of a specific crank period and discriminating misfire based on the result. In addition, as is well known, the microcomputer 3 inputs engine parameters such as the intake air condition and cooling water temperature from the sensor 4 in addition to the reference signal and the unit signal.
The ignition timing and fuel injection amount are calculated, and the igniter 5 and injector 6 are driven based on the results. The precision of the unit signal generating means 1 improves as it becomes finer, but there is no need to set it more finely than necessary, and it is sufficient that it has at least the resolution to divide the ignition period into four equal parts. In other words, 30°C for a 6-cylinder internal combustion engine.
If the A signal is a 4-cylinder internal combustion engine, a resolution of 45° CA signal or higher is sufficient.

Next, regarding the phase of each signal, as is clear from the relationship between the instantaneous rotational speed of the 6-cylinder internal combustion engine and °CA of the internal combustion engine shown in Figure 3, the instantaneous rotational speed is as shown by the solid line in Figure 3(a). has a periodicity in which it drops the most near the top dead center (TDC) of each cylinder, is accelerated by combustion, and then drops again at the top dead center of the next cylinder.

If an abnormality occurs in a particular cylinder and normal combustion is not performed, the rotational speed continues to decrease to the top dead center of the next cylinder without being accelerated, as shown by the broken line in FIG. 3(a). Therefore, in order to measure the instantaneous rotation speed near top dead center, where the combustion result is most noticeable, it is best to set the phase of the unit signal as shown in Figure 3 (C) or (d). (When the pulse signal has a period of 30°C°A and its rising edge is used as an effective edge to measure the period in the range indicated by the arrow).

Below, the abnormal cylinder detection process by the microcomputer 3, which is the main process related to the present invention, will be explained in detail using the flowchart shown in FIG. In FIG. 4, i is the count value of the cylinder number counter, which represents the number of the cylinder in the explosion stroke, and since there are six cylinders in this embodiment, a numerical value from 0 to 5 is used. Further, C(i) is the count value of a cylinder-specific abnormality counter that counts the number of times an abnormality is detected in each cylinder. , the cylinder is determined to be abnormal, and the determination result flag H(i) of the cylinder is set to 1. C is the count value of a unit signal counter that counts unit signals,
In this embodiment, numerical values from 1 to 24 are used to obtain a 30° CA signal in a 6-cylinder internal combustion engine.

Then, the count value c of each counter, c(i),
i is initialized by turning on the key switch to start the engine, and the flowchart in FIG. 4 is executed every time the unit signal (NE signal) rises.

First, in step 90, it is determined whether or not there is a reference signal (G signal). If there is a reference signal, the process proceeds to step 91, and after resetting the unit signal counter C to 0, the process proceeds to step 92. If there is no reference signal, the process proceeds to step 92. Direct step 9
Proceed to 2. Step 92 increments the count value C of the unit signal counter by one. In the next step 93, in order to detect a specific angular position near the top dead center of each cylinder, the remainder when the count value C of the unit signal counter is divided by 4 is 1.
If the remainder is not 1, the specific position is not near the top dead center, so the process proceeds to step 94, and it is determined whether the count value C is 24. If the count value C is 24, the process proceeds to step 95. After proceeding and resetting the count value C to O, the process returns, and if the count value C is other than 24, the process returns directly. Further, in step 93, if it is determined that the remainder of (C÷4) is 1, it is determined that the position is a specific angular position near the top dead center, and step 100 is performed.
Proceed to. In this step 100, the engine at a specific crank timing shown by the arrow in FIG. Rotation speed (instantaneous rotation speed)
Compute NE. , and so on. Next, in step 101, the difference ΔNE from the same calculated value NE, . . . one ignition before is calculated. In step 102, ΔNB is predetermined (iiA
(Here, A>O, for example, 2Orpm),
If the rotation speed drops more than , step 103
Then, the count value C(i) of the cylinder-by-cylinder abnormality counter, which counts the number of abnormality occurrences in the relevant cylinder, is increased by one. Otherwise, the process advances to step 104 and clears the counter value c (D) of the cylinder-specific abnormality counter for the cylinder in question. In the next step 105, a step is performed to determine how many consecutive abnormalities have occurred in the same cylinder. , in the case of this embodiment, if the abnormality determination flag H(i) of the relevant cylinder is set to 1 if it occurs B times or more (for example, 4 times) or more consecutively, the process proceeds to step 106 and sets 1 to the abnormality determination flag H(i) of the relevant cylinder.Steps 107 to 109 Step 110 is for updating the NF, 0-a of the relevant cylinder for the next calculation in step 101.

As a result, a misfiring cylinder can be determined and stored using a relatively simple software configuration. Then, by reading out the abnormality determination flag H(i), it is possible to know which cylinder is misfiring.

In addition, in the embodiment described above, 2 units are used as the unit signal generating means 1.
I have given 4 pulses/2rev (signal every 30° CA), but all you need is a signal at a specific crank angle that is between or sufficiently close to top dead center (not necessarily near top dead center). As shown in FIG. 5, a signal generating means may be used that generates a unit signal only at 15° CA before top dead center and 15° CA after top dead center of each cylinder. Note that during deceleration operation of the engine.

In order to avoid erroneous judgments due to disturbances such as when the engine is cold, the abnormality detection process shown in Figure 4 is executed according to the engine conditions (the execution of the abnormality detection process is stopped during deceleration operation or when the engine cooling water temperature is low). ) is also valid. Also,
According to the present invention, since an abnormal cylinder can be reliably detected, it is also possible to specify the abnormal part by logical operation with the ignition (ignition coil primary voltage) and fuel system (injector current) monitor signals.

Also, step 94.9 in the flowchart of FIG.
5 can be omitted; conversely, this step 94.95
In the case that steps 90 to 92 are provided, steps 90 to 92 may be omitted, and in some cases, the reference signal generating means 2 may also be omitted.

(Effects of the Invention) As described above, in the present invention, a misfiring cylinder is detected based on the fluctuation in the instantaneous rotational speed at a specific rotational angle position of each cylinder of an internal combustion engine. This has the excellent effect of being able to detect misfiring cylinders with high accuracy.

[Brief explanation of drawings]

FIG. 1 is a diagram corresponding to the claims of the present invention, FIG. 2 is a block diagram showing an embodiment of the device of the present invention, FIG. 3 is a waveform diagram of various parts for explaining the operation of the device shown in FIG. 2, and FIG. 2 is a flowchart for explaining the operation of the apparatus shown in FIG. 2, and FIG. 5 is a waveform diagram of various parts for explaining another embodiment of the apparatus of the present invention. DESCRIPTION OF SYMBOLS 1... Unit signal generation means, 2... Reference signal generation means, 3... Microcomputer.

Claims (1)

[Claims] unit signal generating means for detecting a plurality of angular positions per rotation of a multi-cylinder internal combustion engine; and rotational speed detection for detecting the instantaneous rotational speed at a specific rotational position of each cylinder from the angular position interval detected by the unit signal generating means. A misfire detection device for a multi-cylinder internal combustion engine, comprising: a means for detecting an abnormal cylinder; and an abnormal cylinder detecting means for detecting an abnormal cylinder based on a variation in the instantaneous rotational speed at a specific rotational position of each cylinder detected by the rotational speed detecting means.