JPH03121239A - Ignition control method for internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent abnormal ignition by comparing the generated pulse separation between first position signals and second position signals for discriminating specific cylinder so as to discriminate the operating position of each cylinder, and performing by pass ignition control on the basis of the position signals when the discrimination result is judged to be abnormal. CONSTITUTION:A rotary disc 2 on an axis of rotation 1 rotated synchronously with an internal combustion engine is provided with plural slit-like windows 3a, 3b' in the positions corresponding to the reference positions of each cylinder and a specific cylinder. In each window 3a, one end on the front side corresponds to the first reference position of each cylinder, and the other end corresponds to the second reference position, as well as the window 3b' is disposed on the same circumference as the window 3a of the specific cylinder, next to this window 3a. On the basis of the comparison of the generated pulse separation of the first and second position signals, the operating position of each cylinder is discriminated. When the cylinder discrimination result is judged to be abnormal, ignition control based on the cylinder discrimination result is not performed, but by-pass ignition control is performed on the basis of the position signals.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an ignition control method for an internal combustion engine that identifies the operating position of each cylinder based on position signals of one system and controls the ignition of each cylinder. , especially to realize cost reduction,
The present invention relates to an ignition control device for an internal combustion engine that prevents abnormal ignition due to cylinder misdetection.

[Prior Art] Conventionally, internal combustion engines such as automobiles are driven to rotate at several 1100 rpm to several 11000 rpm using a plurality of cylinders (for example, 4 cylinders). In the case of a 4-cylinder, each cylinder is connected to the drive shaft (crankshaft) with a phase difference of 1/2 period, but for two rotations of the crankshaft, intake, compression, explosion, Since exhaust is performed, the operating position of the camshaft that controls the drive cycle of each cylinder is out of phase by 1/4 cycle.

In such an internal combustion engine, in order to electronically control the ignition timing by the igniter for each cylinder, a position signal is generated for each cylinder that is synchronized with the rotation of the internal combustion engine, and based on this position signal, the ignition timing of each cylinder is controlled. It is necessary to identify the operating position.

Usually, a rotation signal generator that detects rotation of a camshaft or crankshaft of an internal combustion engine is used as a means for generating a position signal corresponding to a reference position of each cylinder.

FIG. 2 is a block diagram showing a general cylinder identification device for internal combustion engines. In the figure, (8) is a rotation signal generator that generates a position signal corresponding to each cylinder, and (9) is a position signal generator. The interface circuit (10) is a microcomputer that processes the position signal input via the interface circuit (9) to identify the operating position of the cylinder.

FIG. 3 is a perspective view showing a specific configuration example of a rotation signal generator (8) used in a conventional internal combustion engine cylinder identification device, and FIG. 4 is a perspective view showing a position signal provided in the rotation signal generator (8). FIG. 3 is a circuit diagram showing a generating section.

In FIG. 3, (1) is a rotating shaft that rotates in synchronization with the internal combustion engine; for example, it is connected to a camshaft that rotates once in synchronization with one cycle of operation of the internal combustion engine (or one cylinder consisting of it). ing.

(2) is a rotating disk attached to the rotating shaft (1), and there are a plurality of rotary discs at positions corresponding to the reference position (predetermined rotation angle) for each cylinder, as well as at positions corresponding to the reference position of a specific cylinder. Slit-shaped windows (3a) and (3b) are provided. Here, the case where the internal combustion engine is a four-cylinder engine is shown, and regarding the windows (3a) provided at four locations along the outer periphery, one end on the front side with respect to the rotation direction (arrow) is the first end of each cylinder.
corresponds to the reference position, and one end on the rear side corresponds to the second reference position.

Further, the window (3b) provided at one location on the inner circumference is arranged to correspond to the window (3a) of only one specific cylinder (first cylinder), and has a phase difference with respect to the window (3a). have.

(4a) and (4b) are a pair of light emitting diodes arranged to face the good intentions (3a) and (3b), respectively, and (5a) and (5b) are light emitting diodes from each light emitting diode (4a) and (4b). A pair of photodiodes arranged to receive output light through windows (3a) and (3b).

These light emitting diodes (4a) and (4b) and photodiodes (5a) and (5b) constitute two sets of photocouplers.

In FIG. 4, light emitting diodes (4a) and (4b)
The photodiodes (5a) and (5b) are typically shown as (4) and (5), and only one photocoupler is shown. (6) is an amplifier circuit that amplifies the output signal from the photodiode (5); (7)
is an open collector/grounded emitter output transistor whose base is connected to the output terminal of the amplifier circuit (6). The collector terminal of the output transistor (7) is connected to an interface circuit (9) (see FIG. 2).

Next, the operation of the conventional internal combustion engine cylinder identification device shown in FIGS. 2 to 4 will be described with reference to the waveform diagram in FIG. 5.

When the rotating shaft (1) rotates and the rotating disk (2) rotates as the internal combustion engine rotates, the rotation signal generator (8) outputs the following:
Each photodiode (5a) and (5b) of two sets of photocouplers are arranged facing each other with windows (3a) and (3b) in between.
), two types of position signals L1 and L2 (see FIG. 5) are output, which rise at the front end and fall at the rear end of the slits forming the windows (3a) and (3b).

In FIG. 5, the first position signal L1 obtained based on the window (3a) is a crank angle reference signal called SGT, and is inverted at a predetermined crank angle for each cylinder #1 to #4. Here, each crank angle reference signal rises at a crank angle of 0°, which is called B75° for each cylinder.
The trailing edge indicates a first reference position 75 degrees before the position (TDC - upper dead center), and the trailing edge indicates a second reference position 5 degrees before TDC, called B5°. usually,
The first reference position B75° corresponds to the control reference angle, and the second reference position B5° corresponds to the initial ignition angle.

Also, the second position signal L2 obtained based on the window (3b)
is a cylinder identification signal called SGC, and a specific #1
It is output when a cylinder signal is generated and is used to identify the #1 cylinder.

The operating position of each cylinder is shifted by 1/4 period with respect to one period of the camshaft (corresponding to two periods of the crankshaft, or 720 degrees), and is deviated by 1/2 period with respect to one period of the crankshaft. They are shifted by a period (180°). Further, as is well known, each cylinder operates in the order of #1 cylinder, #3 cylinder, #4 cylinder, and #2 cylinder.

On the other hand, the cylinder identification signal L2 is set to rise before the rise of the crank angle reference signal L1 corresponding to the specific #1 cylinder, and fall after the fall of the position signal L1.

The two types of position signals obtained in this way and L2 are input to the microcomputer (10) via the interface circuit (9). Then, the second position signal L2
The specific #1 cylinder is identified based on the first position signal, and the operating position of each cylinder #2 to #4 is identified based on the first position signal, which is used for ignition timing control calculation.

However, in the cylinder identification system M as described above, since two systems of position signals and L2 are used, the configuration of the rotation signal generator (8) becomes complicated, and there is a problem that cost reduction cannot be achieved. be.

Therefore, it is possible to consider an apparatus that uses a rotation signal generator (8) as shown in FIG. 6 to transmit one system of position signals L1 and L2'. In this case, the light emitting diode (4) and the photodiode (5) constitute a set of photocouplers. Further, (3b') is a window for identifying a specific cylinder corresponding to the window (3b), and a window (3b') for detecting the reference crank angle is a window for identifying a specific cylinder.
It is located on the same circumference as a).

The window (3b') for identifying the specific cylinder is placed next to the window (3a) that indicates the first and second reference positions of the specific cylinder. Two position signals Ll and L2' are obtained.

In FIG. 6, the other configurations are the same as in FIG. 3, and
The configuration of the entire device and the configuration of the position signal generator are as shown in FIGS. 2 and 4, respectively.

Next, a cylinder identification method using the rotation signal generator 8) of FIG. 6 will be described with reference to the waveform diagram of FIG. 7 and the flowchart of FIG. 8.

Similarly to the above, when the rotating disk (2) rotates in the direction of the arrow, the rotation signal generator (8) is From then on, continuous first and second position signals L2' are generated as shown in Fig. 7.Here, the fall of the second position signal L2' indicates that a specific cylinder On the other hand, it corresponds to a reference position called A5° which is 5° after TDC.

Next, the microcomputer (10) (see Figure 2) connects the rotation signal generator (8) to the interface circuit (9).
), the high level period (pulse width) of each position signal is determined by Step St to calculate the rising cycle (pulse interval) T
), and further calculates the duty (t/T) of each pulse based on the value obtained in step S1 (step S2
). Then, based on the calculation result in step S2, the previous data (t/T) n-1 and the current data (t/T) are
T) Take the absolute value of the difference from n, and determine whether this value is larger than a predetermined value α (step S3).

If 1 in Figure 7. When the duty (t/T) changes greatly, such as from T1 to t2 and T2, it is determined that the absolute value of the ratio data difference is greater than the predetermined value α, and the specific #1 cylinder is identified. Ru.

Therefore, after the flag representing the specific cylinder (#1 cylinder) is set in the register in the microcomputer (10) (step S4), the process returns to end the cylinder identification operation (step S5).

On the other hand, if it is determined in step S3 that the absolute value of the duty difference is less than or equal to the predetermined value α, the process immediately returns (step S5) and the #3 The cylinders, #4 cylinder and #2 cylinder are sequentially identified.

In this way, by recognizing the position signal corresponding to each cylinder, the ignition coil of each cylinder can be de-energized, for example, at a predetermined optimum timing. At this time, the second position signal L2' for identifying the specific cylinder is
It occurs after the fall of the first position signal Ll and is set after the initial ignition position (B5°), so when cranking between the internal combustion engines (when starting the crank by motor drive), as shown in FIG. Even if the position signal L2' is used as it is to cut off the ignition coil's current (ignition at the falling edge), and the ignition coil's current is cut off using the second position signal L2' for identifying a specific cylinder, the first position signal Since this is after the normal initial ignition by L1, there will be no starting failure of the internal combustion engine. Although the pulse duty (L/T) of each position signal was calculated in step S2 above, the low level period (T - t)
The ratio of the high level period t to [t/ (T - t>
] may be calculated. In this case, the period difference due to the pulse interval variation becomes large, and the detection sensitivity of a specific cylinder is further improved.

However, one line of position signal as described above and L2
In the cylinder identification method using ′, during cranking (
When the rotation cycle fluctuates, such as during the initial startup period of the internal combustion engine, the generation cycle of the first position signal (crank angle reference signal 5GT) L changes, and abnormal cylinder identification results due to erroneous detection are reflected in ignition control. .

[Problem M to be Solved by the Invention] As described above, the conventional ignition control method for an internal combustion engine uses two sets of photocouplers to identify cylinders based on two systems of position signals L1 and L2. Since it is necessary to generate a system signal, there is a problem in that the configuration of the rotation signal generator becomes complicated, leading to an increase in cost.

In addition, an ignition control method for an internal combustion engine in which cylinder identification is performed using one system of position signals L1 and L2' is such that the first
When the generation cycle of the position signal L1 fluctuates, there is a problem in that abnormal cylinder identification results due to erroneous detection are reflected in ignition control, leading to problems due to abnormal ignition.

This invention was made to solve the above-mentioned problems, and it is an internal combustion engine that uses one system of position signals for cylinder identification to reduce costs and prevent abnormal ignition due to erroneous detection of cylinder identification. The purpose is to obtain an ignition control method for

[Means for Solving the Problem] The ignition control method for an internal combustion engine according to the present invention generates a second position signal for identifying a specific cylinder following the first position signal, and The operating position of each cylinder is identified based on a comparison of signal generation pulse intervals, and if the cylinder identification result is determined to be incorrect, ignition control based on the cylinder identification result is not performed, and bypass ignition is performed based on the position signal. It is designed to perform control.

[Operation] In the present invention, after performing cylinder identification based on the pulse interval of one system of position signals, it is determined whether the identification result is normal or not, and if it is normal, ignition control is performed based on the identification result, If it is not normal, bypass ignition control is performed using the position signal to ensure good starting operation.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. 1st
The figure is a flowchart showing an embodiment of the present invention, and steps 51 to S5 are the same as those described above. Further, the apparatus to which this invention is applied is as shown in FIGS. 2, 4, and 6, and one system of position signals generated for cylinder identification is the same as in FIG. 7. . Therefore, as mentioned above, the rising edge of the first position signal (B7) shown in FIG.
5°) is set as the reference angle for control, and the falling edge (B5°) is set as the initial ignition angle.

In FIG. 1, after steps S1 to S4 for cylinder identification (not explained here) are completed, it is determined whether the cylinder identification result is normal or not (step S6), and if it is normal, based on the identification result. Perform normal ignition control (step S
7).

On the other hand, if it is determined in step S6 that the identification result is not normal, bypass ignition control using conventional mechanical cylinder identification and position signals is performed (step S8).

That is, current is supplied to the ignition coil at the rising edge (B75°) of the first position signal L1, and at the falling edge (B75°) of the first position signal L1, the current is supplied to the ignition coil.
5°), the current is cut off and ignition occurs. Regarding the #1 cylinder, power is cut off by the second position signal L2', but as mentioned above, since it has just been ignited by the first position signal L2', there is no change in the operating state of the internal combustion engine. No problems will occur.

The above-described determination step S6 and bypass ignition step S8 are executed by the microcomputer (10). This prevents abnormal cylinder identification results due to erroneous detection from being used for ignition control, and ensures a good operating state even in the initial stage of startup.

The determination in step S6 is made, for example, based on the contents of the register in which the flag is set, and if the contents of the register corresponding to every four cylinders are rloooo.

If so, the identification result is determined to be normal. Furthermore, if the pulse interval of the position signal becomes unstable, such as at the beginning of startup, the flag is not set only for a specific cylinder and the contents of the register become abnormal, so it is determined that the register is not normal.

[Effects of the Invention] As described above, according to the present invention, the second position signal for identifying a specific cylinder is generated following the first position signal, and the generation pulse interval of the first and second position signals is The operating position of each cylinder is identified based on the comparison, and if it is determined that the cylinder identification result is not normal, ignition control is not performed based on the cylinder identification result, bypass ignition control is performed based on the position signal, and cylinder identification is performed. Since the identification result at the time of failure is not reflected in the ignition control, it is possible to achieve an ignition control method for an internal combustion engine that reduces costs and prevents abnormal ignition due to incorrect cylinder identification.

[Brief explanation of drawings]

FIG. 1 is a flow chart diagram showing an embodiment of the present invention;
Fig. 2 is a block diagram showing a general cylinder identification device for internal combustion engines, Fig. 3 is a perspective view showing a rotation signal generator used in the conventional cylinder identification device for internal combustion engines, and Fig. 4 is a block diagram showing a general cylinder identification device for internal combustion engines. A circuit diagram showing a position signal generator provided in a signal generator, FIG. 5 is a waveform diagram showing a position signal generated by the rotation signal generator of FIGS. 3 and 4, and FIG. 6 is a diagram showing an improved rotation signal generator. A perspective view showing a signal generator, FIG. 7 is a waveform diagram showing a position signal generated by the rotation signal generator of FIG. 6, and FIG. 8 is an ignition diagram for an internal combustion engine using the rotation signal generator of FIG. 6. FIG. 3 is a flowchart diagram for explaining a control method. (8)...Rotation signal generator B75°...First reference position B5°...Second reference position Ll...First position signal L2'...Second position signal S1 ~S4...Step S6 for identifying the cylinder...Step S8 for determining the identification result...Step for bypass ignition control Note that in the drawings, the same reference numerals indicate the same or corresponding parts. Figure 1

Claims (1)

[Claims] In synchronization with the rotation of the internal combustion engine, a first reference position corresponding to each of the plurality of cylinders and a second reference position near the initial ignition position are set.
generating a first position signal indicating a reference position of the first position signal and a second position signal for identifying a specific cylinder following the first position signal, and comparing generation pulse intervals of the first and second position signals. In the ignition control method for an internal combustion engine, in which the operating position of each cylinder is identified based on the identification result, and the ignition of each cylinder is controlled based on the identification result, if the cylinder identification result is determined to be incorrect, the An ignition control method for an internal combustion engine, characterized in that bypass ignition control is performed based on the position signal without performing ignition control based on the cylinder identification result.