JPH029184B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ignition timing control device for a spark-ignition internal combustion engine.

As an ignition timing control device, one shown in FIG. 1, for example, has been proposed. That is, control circuit 2
1 is an input/output device 22, CPU 23, ROM 24,
The input/output device 22 is composed of a RAM 25, and inputs signals from a rotational speed sensor 26, an intake air flow rate sensor 27, and a throttle valve fully closed detection switch 28, and sends an ignition signal pulse that is calculated and controlled based on these input signals to a transistor 29. Output. The ignition signal pulse amplified by the transistor 29 is supplied to the ignition coil 30, and the high voltage pulse generated on the secondary side of the coil 30 is supplied to the ignition plug 32 of each cylinder via the distributor 31. A spark is generated in the ignition plug 32 and ignited.

Ignition timing control (pulse generation timing) in the control circuit 21 is performed as follows according to the flowchart shown in FIG. That is, when the throttle valve is detected to be fully closed, the advance value is searched based on the engine rotation speed from characteristic A shown in Figure 3, and when the throttle valve is not fully closed, the advance angle value is searched based on the engine rotation speed and the intake air amount. The advance angle value is retrieved from the characteristic B shown in FIG. 4, which has been experimentally determined in advance, and a pulse with ignition timing controlled thereby is output.

However, with the conventional configuration in which ignition timing is essentially determined only by the engine speed and intake air amount, the ignition timing is not necessarily controlled to the optimal level when considering variations in performance between engines, changes over time, etc. However, I could not say that.

The present invention has been made in view of the above circumstances, and provides an ignition timing control device for an internal combustion engine that is configured to correct and control the ignition timing based on the actual combustion state of the engine.

The present invention will be explained in detail below based on illustrated embodiments. The embodiment shown in FIGS. 5 to 8 is applied to a 4-stroke, 6-cylinder engine. In the figure, the engine body (not shown) includes a conventional rotational speed sensor 1, intake air amount sensor 2, throttle valve fully closed detection switch 3, as well as a cylinder discriminator 4 and a pressure sensor 5.
are provided, and the detection signals from these are inputted to the input/output device 7 of the control circuit 6. Here, pressure sensor 5
corresponds to means for detecting a quantity correlated to the combustion chamber pressure. The control circuit 6 includes the input/output device 7 as well as the CPU 8,
The ignition circuit, which is composed of a ROM 9 and a RAM 10 and whose ignition timing is controlled by a control circuit 6, is composed of a transistor 11, an ignition coil 12, a distributor 13, a spark plug 14, etc., as shown in FIG. .

The rotational speed sensor 1 generates a reference position signal at 70 degrees before the compression top dead center of each cylinder every 120 degrees of crank angle (every explosion stroke), and also generates an angle signal every 2 degrees of crank angle. The cylinder discriminator 4 generates a signal at 80 degrees before the compression top dead center of the No. 1 cylinder. The pressure sensor 5 is built into a gasket interposed between the cylinder bed and cylinder block of the engine, and continuously detects a pressure value correlated to the combustion pressure of each cylinder and outputs a signal. These signals are then sent to the input/output circuit 7.
Each time a signal is input to the CPU 8 via the CPU 8, the CPU 8 performs calculations as follows.

That is, when the signal from the cylinder discriminator 4 is input,
The CPU 8 resets a built-in counter 8A, and then counts up the counter 8A every time an angle signal is input. Therefore,
The rotational speed sensor 1, the input/output device 7, and the counter 8A constitute means for detecting the crank angle of each cylinder from the reference crank angle position.
Additionally, in parallel with this, the analog value input from the pressure sensor 5 is converted into a digital value. Furthermore, set the count value of counter 8A to 0, 60, 120, 180,
Divided by 240, 300, and 0, from the count value when the maximum value of the digital value is input in each section,
The count value at the beginning of the section (e.g. 60 to 120)
In the interval, calculate the value θ by subtracting 60) and store it in RAM.
to be memorized. This value θ indicates that the maximum value Pmax of the pressure detected in each cylinder by the pressure sensor 5 is 2θ−80 in terms of crank angle (°) after compression top dead center. (See Figure 6). Therefore, the CPU 8 that performs such calculations and the RAM 10 that stores the calculated values constitute means for detecting and storing the crank angle from the reference crank angle position when the combustion chamber pressure is at its maximum. θ is determined for each section of the count value, but each time the CPU 8 determines θ, it calculates the maximum and minimum 2 from the latest four θ (θ ₁ , θ ₂ , θ ₃ , θ ₄ ).
The average value θ ₀ of the remaining two values is calculated, and this value θ ₀ is stored in the RAM 10. Therefore,
The CPU 8 that performs such calculations and the RAM 10 that stores the calculated values calculate the average value of the remaining values by excluding the maximum and minimum values from among the latest and past predetermined crank angles at the time of maximum pressure in the combustion chamber. A means to do so is constructed. In this way, the maximum and minimum 2
The configuration is such that the average value θ ₀ of the remaining values is calculated, so that the crank angle at the maximum pressure in the combustion chamber corresponding to the ignition timing is avoided as much as possible from the influence of errors caused by variations and intake pulsation. This requires high accuracy, which in turn can improve the ignition timing control accuracy, which will be described later.

Next, when the reference position signal is output from the rotational speed sensor 1, first, as in FIG. 1, when the throttle valve fully closed detection switch 3 is ON, the characteristic A shown in FIG. In this case, the advance angle value M is searched from the characteristic B shown in FIG. Therefore,
The ROM 9 that stores the advance angle value M and the CPU 8 that searches for the advance angle value M constitute means for setting the basic ignition timing based on the engine operating state.

Next, set the above θ ₀ and a predetermined value K (K = 45° to 90°: Although it differs slightly depending on the engine, the maximum value of the pressure in the combustion chamber is determined at a crank angle of 10° to 20° after compression top dead center. The ignition timing correction coefficient m is determined by comparing the ignition timing correction coefficient m with the value determined so that the torque generated by the engine is maximized when the ignition timing is set so that the ignition timing is set at this position. For example, as shown in Figure 7, how to determine m is K
The increase/decrease of θ ₀ is performed using proportional-integral control. The CPU 8, which determines the ignition timing correction coefficient m, constitutes means for setting the ignition timing correction amount based on the deviation between the average value and the set value set as the crank angle that maximizes the torque of the engine.

Then, M+m is calculated, and the next ignition timing is controlled to be M+m before compression top dead center in terms of crank angle. Specifically, the input/output device 7 has a register 7.
A, a counter 7B, and a comparator 7C, which operate as follows (Fig. 8). Counter 7B becomes 0 when the reference position signal is input, and when the 2° signal rises,
Start counting the falling edge (every 1°). On the other hand, when the reference position signal is input to the register 7A, the value 70-(M+m) is stored based on the above-mentioned calculation. The comparator 7C compares the value of the counter 7B and the value of the register 7A, and when the two become equal, the output to the transistor 11 is changed from ON to OFF, causing the ignition plug 14 to spark and ignite. The reference position signal is generated at 70° before compression top dead center of each cylinder, so
When the value of counter 7B becomes 70-(M+m),
That is, the ignition timing is the crank angle before the compression top dead center and M+m [°] before the top dead center (see FIG. 8). Therefore, the register 7A, the counter 7B, the comparator 7C, and the CPU 8 constitute means for controlling the ignition timing by correcting the basic ignition timing by the set ignition timing correction amount.

In this way, since the configuration is configured to perform correction control by detecting the correlation amount between the ignition timing and the combustion pressure indicating the actual combustion state, the ignition timing can be controlled with high precision in response to engine-to-engine variations and the passage of time.

Note that a pressure sensor may be provided for each cylinder, or one pressure sensor may be used to detect pressure changes in all cylinders.

As explained above, according to the present invention, a quantity correlated with combustion pressure is detected, and the ignition timing is controlled in accordance with the crank angle at the maximum pressure in the combustion chamber, which is determined with high precision based on this detected value, making it optimal. The engine can be operated with accurate ignition timing, stabilizing and improving engine performance.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing a conventional ignition timing control device for an internal combustion engine, Fig. 2 is a flow chart showing the operating process of the above device, and Figs. Figure 5 is a block diagram showing an embodiment of the present invention, Figure 6 is a graph showing the relationship between crank angle and combustion pressure, Figure 7 is the same as above. FIG. 8 is a graph showing a method for determining the ignition timing correction coefficient in the embodiment, and FIG. 8 is a graph showing the ignition timing control method in the same embodiment. DESCRIPTION OF SYMBOLS 1... Rotation speed sensor, 2... Intake air amount sensor, 3... Throttle valve fully closed detection switch, 4... Cylinder discriminator, 5... Pressure sensor, 6... Control circuit, 7
...Input/output device, 8...CPU, 9...ROM, 1
0...RAM, 11...Transistor, 12...
Ignition coil, 13...distributor, 14...ignition plug.

Claims (1)

[Claims] 1. Means for detecting a quantity correlated to the combustion chamber pressure, means for detecting the crank angle from the reference crank angle position of each cylinder, and a means for detecting a quantity correlated to the combustion chamber pressure, and a means for detecting the maximum combustion chamber pressure based on the detected value of the quantity correlated to the combustion chamber pressure. means for detecting and storing the crank angle from the reference crank angle position when means for calculating an average value of the engine; means for setting an ignition timing correction amount based on the deviation between the average value and a preset value as a crank angle that maximizes engine torque; An internal combustion engine characterized by comprising: means for setting a basic ignition timing; and means for controlling the ignition timing by correcting the basic ignition timing by the set ignition timing correction amount. Engine ignition timing control device.