JPH0711268B2 - Ignition timing control device for internal combustion engine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an ignition timing control device for an internal combustion engine, and particularly to a light load operation in which the relationship between the combustion pressure peak crank position (hereinafter referred to as θpmax) and the ignition timing is unstable. The present invention also relates to an ignition timing control device that enables accurate ignition timing control, that is, ignition timing control immediately before reaching a flat shaft torque (hereinafter referred to as MBT advance angle control).

[Problems to be Solved by Prior Art and Invention]

A device that detects the peak crank position of the schilling internal pressure, that is, θpmax, using the engine shaft rotation angle reference position signal and adjusts the ignition position to the optimum position (JP-B-49-2920).
9) or a device (Japanese Patent Publication No. 56-21913) for adjusting the ignition timing so that θpmax becomes a predetermined value according to the operating state has already been proposed.

However, these documents do not disclose control of θpmax and ignition timing during light load operation. That is, the combustion becomes unstable at θpmax during light load operation (for example, at a light load where the intake pipe negative pressure is less than −450 mm Hg), and the variation amount of θpmax between cycles tends to increase. For this reason, the relationship between θpmax and the ignition timing becomes unstable, and it is difficult to perform optimum MBT advance angle control with the conventional technology.

[Means and Actions for Solving Problems]

The present invention is to provide an ignition timing control device capable of performing optimum MBT advance angle control even during light load operation.In the present invention, in light load operation, θpmax variation as the ignition timing is delayed from the MBT advance angle. Paying attention to the tendency that the amount is increasing, when the engine load is below a predetermined value (for example, the intake pipe negative pressure is lighter than -450 mm Hg), the ignition timing is reduced in order to reduce the change amount of θpmax between the predetermined rotation speeds. (EN) An ignition timing control device capable of performing MBT advance control at a light load by advancing a predetermined amount.

A block diagram showing the principle of the present invention for achieving this object is shown in FIG. Referring to FIG. 1, the present invention relates to a combustion pressure detecting means 2 attached to at least one combustion chamber of an internal combustion engine, and a crank angle detecting means 3 attached to a distributor or a crankshaft for detecting a crank angle of the internal combustion engine 1. And a target crank position calculating means 4 for calculating a target crank position corresponding to an internal combustion engine speed determined based on a crank angle signal detected by the crank angle detecting means 3, and a combustion pressure detecting means 2. Ignition timing control means 5 for determining a combustion peak crank position, which is a crank angle at which the combustion pressure reaches a peak, and controlling ignition timing so that the combustion peak crank position becomes the target crank position calculated by the target crank position calculation means 4. The crank angle detected by the crank angle detection means at light load is When the variation amount of the combustion peak crank position between the predetermined rotational speeds is equal to or more than a predetermined threshold value in the range of, the ignition timing control means advances the ignition timing instead of controlling the ignition timing. The corner means 6 is provided.

〔Example〕

FIG. 2 is a system diagram of the present invention. In FIG. 2, 1 is an internal combustion engine, 7 is a combustion pressure sensor attached to at least one combustion chamber of the internal combustion engine 1, 8 is a distributor,
Reference numeral 9 is an electronic control device for calculating a target crank position and an ignition timing adjustment amount, 10 is an igniter, and 11 is a fuel injection valve.
The combustion pressure sensor 7 detects the combustion pressure in the cylinder and also works in conjunction with a distributor or a crankshaft.
A crank angle signal composed of a pulse-shaped reference signal generated every 720 ° CA and a pulse-shaped angle signal generated at every predetermined angle (for example, every 1 ° CA) is used to detect a crank angle provided on the distributor 8 or the crankshaft. The engine speed is generated based on the crank angle signal generated from the sensor 3, and the target crank position is calculated by the electronic control unit 9 according to the engine speed. Further, the electronic control unit 9 calculates θpmax and a cycle-to-cycle variation amount (Δθpmax) in a predetermined crank angle range (for example, 180 ° CA before and after compression top dead center) according to the crank angle, and Δθpmax
The ignition timing adjustment amount is calculated according to the deviation between the target crank position and the value of θpmax. Based on the calculation result of the electronic control unit 9 thus obtained, the igniter 10
Fires a spark depending on the ignition timing.

FIG. 3 is a detailed block diagram of the electronic control unit shown in FIG. In FIG. 3, an electronic control unit 9 is an A / D converter 9a and an input interface 9 interconnected by a bus BUS.
It is composed of a central processing unit (CPU) 9c including b, ROM, RAM and the like and an output interface 9d. The analog signal from the combustion pressure sensor 7 installed in the combustion chamber is A / D
It is converted into a digital value in the converter 9a and sent to the CPU 9c. In addition, a pulse-shaped reference signal 8a and an angle signal 8b generated in conjunction with the distributor or the crankshaft.
Is sent to the input interface 9b, and the CPU 9c performs predetermined arithmetic processing. The calculation result of the CPU 9c is sent to the igniter 10 via the output interface 9d to control the ignition timing.

4 and 5 show control flowcharts of the ignition timing control device for the internal combustion engine according to the present invention. It should be noted that although the processing of one cylinder is shown in the present embodiment, the processing can be performed by using the combustion pressure data of a plurality of cylinders by executing the same processing for each cylinder.

FIG. 4 shows each crank angle sensor angle signal (for example, 1
The processing executed for each CA) is shown. Check the state of the reference signal (every 720 ° CA) in steps 41, 42 and 43,
If it is N, the crank angle counter (CL) is reset. When FF, CL + 1 is executed. From the above, the crank angle position of the engine can be known. For example, when the reference signal is generated at the position of 180 ° CA before compression top dead center of the pressure detection cylinder, when CL = 0, 180 ° CA before compression top dead center, CL = 1
At 80, compression top dead center is reached, and at CL = 360, 180 ° CA after compression top dead center. In step 44, 0 ≦ CL ≦ 36 from the CL value
Only when it is 0, the following steps 45 to 48 are executed.
In steps 45 to 48, the combustion pressure value (P) is detected every 1 ° CA by A / D conversion to detect the peak position. CL ＝
When 0, the detected pressure value (P) is compared with the pmax value that is reset in RAM in advance, and when P> Pmax, Pmax
← P, θpmax ← CL is executed. CL is 0 to 360
During this period, the pressure peak crank position (θpmax) during one cycle can be obtained. Here, when the peak crank position is 18 ° CA after the compression top dead center, the value of θpmax is
180 + 18 = 198.

FIG. 5 shows the processing executed every 720 ° CA (every cycle). The process shown in FIG. 5 is the same as the CL shown in FIG.
It is desirable to be executed at the point of = 360. In this embodiment, in step 501, the average of the θpmax values for 5 cycles and the variation amount between cycles are obtained.
It is not limited to cycles. A counter (C5CYCL) for detecting the 5 cycles is counted up. It should be noted that C5CYCL is reset after execution of processing every 5 cycles. In step 502, Σθpmax ← Σθpmax +
Perform θpmax. Σθpmax is reset every 5 cycles. That is, RAM for 5 cycles of θpmax integration
To use. Θ during 5 cycles in steps 503-509
Detect the minimum (MIN) and maximum (MAX) of pmax.

Only when C5CYCL = 5, that is, 5 cycles of θpmax are sampled in step 510, the following steps 511 are performed.
Perform processing from ~ 517. In step 511, the θpmax average value (θ _AV ) for 5 cycles is calculated. Step 512
Check engine load at. For example, if the intake pipe negative pressure (Pm) is less than -450 mm Hg, step 51
If it is NO, go to step 514. Step 513
Variation of θpmax during 5 cycles (MAX-MI
N) and the set value k (for example, 5 ° CA) are compared, and (MAX-MI
When N)> k, the routine proceeds to step 515, where the ignition timing is adjusted to the advanced side. If (MAX-MIN) ≤ k, step
Continue to 514. In steps 514 to 516, θ _AV is compared with a target value stored in RM in advance according to the engine state (for example, the engine speed is calculated as a parameter), and θ _AV ≧ the target value, that is, the pressure peak crank position. Is advanced from the target crank position, the ignition timing is adjusted to the advanced side, and when θ _AV <target value, the ignition timing is adjusted to the delayed side. In step 517 C5CYCL, Σθ
The RAM values such as pmax and Pmax are reset, and the process ends.

By performing the control shown in FIGS. 4 and 5 above, good MBT advance angle control can be realized even in the light load region where combustion becomes unstable.

The effects of the present invention will be described with reference to FIGS.

FIG. 6 shows the in-cylinder pressure (combustion pressure) in the crank angle range of 180 degrees before and after compression top dead center, A is the motoring, and B and B'are the pressures during light load operation. B and B'show a waveform (B) at the time of comparatively good combustion and a waveform (B ') at the time of comparatively bad combustion among the pressure waveforms continuously measured under the same operating conditions. As is clear from the figure, the cylinder internal pressures greatly differ between B and B '.

FIG. 7 shows the relationship between θpmax at the ignition timing before and after the advance of MBT, (a) intake pipe negative pressure = −480 mm Hg and (b) −360 mm.
It shows about Hg. At −360 mm Hg in (b), the variation amount between θpmax between cycles is as small as ± 2, and the correlation of the θpmax average value with the ignition timing is strong. Also, at -480 mm Hg in (a), on the leading side from the MBT advance angle, (b)
However, the amount of variation between cycles of θpmax increases on the delay side of the MBT advance angle, and the average value of θpmax does not change. Although not shown, on the lighter load side, the θpmax average value may shift to the top dead center side from the MBT advance angle to the delay side. From the above, according to the conventional technology, since there is no correlation between the ignition timing and θpmax at light load, accurate MB
T advance angle control becomes impossible.

Further, in the present invention, focusing on the relationship between the ignition timing and the variation amount between θpmax between cycles, as shown in FIG.
It is done.

〔The invention's effect〕

According to the present invention, even during light load operation, the relationship between the combustion pressure peak crank position and the ignition timing is stable, accurate ignition timing control is possible, and efficient engine operation is possible.

[Brief description of drawings]

FIG. 1 is a block diagram showing the principle of the present invention, FIG. 2 is a system diagram of the present invention, FIG. 3 is a detailed block diagram of the electronic control unit of FIG. 2, and FIG. 4 is one embodiment control of the present invention. A flow chart, FIG. 5 is a control flow chart of another embodiment of the present invention, and FIGS. 6 and 7 are graphs for explaining the effect of the present invention. (Description of symbols) 1 ... Internal combustion engine, 2 ... Combustion pressure detection means, 3 ... Crank angle detection means, 4 ... Target value calculation means, 5 ... Ignition timing adjustment amount calculation means, 6 ... Ignition means , 7 ... Combustion pressure sensor, 8 ... Distributor, 9 ... Electronic control unit, 10 ... Igniter, 11 ... Fuel injection valve.

Claims (1)

[Claims] 1. A combustion pressure detecting means attached to at least one combustion chamber of an internal combustion engine, a crank angle detecting means attached to a distributor or a crankshaft for detecting a crank angle of the internal combustion engine, and the crank angle detecting means. Target crank position calculating means for calculating the target crank position corresponding to the internal combustion engine speed determined based on the crank angle signal detected by the crank angle signal, and the crank angle at which the combustion pressure detected by the combustion pressure detecting means reaches a peak. Ignition timing control means for controlling the ignition timing so as to determine the combustion peak crank position, which is the target crank position calculated by the target crank position calculation means. In the timing control device, when the load is light, the crank angle detection means When the variation amount of the combustion peak crank position between the predetermined rotation speeds when the detected crank angle is within a predetermined range is equal to or greater than a predetermined threshold value, the ignition timing control means is replaced with the ignition timing control. Ignition timing control device for an internal combustion engine, further comprising advance means for advancing the ignition timing.