JPS58143169A - Method for controlling ignition timing - Google Patents

Abstract

PURPOSE:To enable ignition timing to be controlled according to the kind of used fuel by judging the kind of fuel on the basis of whether or not knocking is produced under the predetermined condition of an engine in an ignition timing control of an internal-combustion engine. CONSTITUTION:In step 202, is judged a flag Fr showing whether or not ignition timing for regular travelling is corrected from the start to the present time of point of an engine. In step 205, is judged whether or not there is knocking. When the knocking is produced in the range of rotational frequency of about 1,500-4,000rpm, the kind of used fuel is judged as regular travelling fuel and flag Fr is set. When knocking is not produced, fuel used is judged to be of high octane. When fuel used is judged to be used regular travelling fuel the angle of ignition timing is delayed and this control is carried out for a predetermined time until the engine is stopped. Thus, the ignition timing can be controlled according to the fuel used.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling the ignition timing of an engine, and particularly to a method for controlling the ignition timing of an engine using high octane fuel.

In recent years, as regulations against air pollution have been tightened, the use of high-octane fuels containing lead compounds such as tetraethyl lead has been restricted.

Therefore, the engine had to be designed to use so-called regular unleaded octane fuel (75-85), and the compression ratio was made relatively low to suppress engine knock. .

In addition, when considering the efficiency of the engine such as output, it is preferable to have a compression ratio as low as possible.Also, recently, high octane fuel without the addition of lead compounds has been developed, so an engine that aims to use high octane fuel will be provided again. It is being done.

Also, if normal octane fuel (hereinafter simply referred to as regular) is mistakenly used in an engine designed to use Karasu octane fuel (hereinafter simply referred to as high-octane fuel), or if high-octane fuel is not available and regular is unavoidably used. In this case, engine knock (hereinafter simply referred to as knock) occurs frequently, making it impossible for the engine to achieve its full performance, and in the worst case, the engine may be damaged. Therefore, in order to solve this problem, two ignition timings are prepared in advance, one for regular and one for high-octane, and when using regular, the ignition timing for regular is specified by operating a switch, and the ignition timing is retarded. A method has been proposed to protect the engine by placing it on the corner side.

However, such a method requires the driver to constantly be aware of the type of II charge being used. For example, if for some reason you use the regular version and then use the high-octane version, even if you forget to reset the switch to the high-octane version, there will be no knocking and the driver will notice that the switch has been set incorrectly. Therefore, in such cases, even though a high-octane engine is used, the engine performance cannot be fully utilized.

An object of the present invention is to provide an ignition timing control method that eliminates the drawbacks of the conventional methods. This purpose is to control the ignition timing using a preset required advance value for high octane fuel, and to perform processing to correct the ignition timing to the retarded side when engine knock is detected under predetermined engine conditions. This is also achieved by continuing the ignition timing correction process after the correction process until the engine stops or until a certain period of time has elapsed.

The present invention will be explained below by giving examples and referring to the drawings.

First, FIG. 1 is an explanatory diagram showing an engine and its peripheral equipment to which the method of the present invention is applied. In this figure, 1 is the engine, 2 is the piston, 3 is the exhaust manifold,
4 is an exhaust valve, 5 is a spark plug, 6 is an intake valve, 7 is an intake manifold, 8 is a fuel injection valve, 9 is a throttle valve, 10 is an air 70-meter, 11 is an intake temperature sensor, 12 is an igniter, 13 is A distributor, 14 a cylinder discrimination sensor provided in the distributor, 15 a rotation angle sensor also provided in the distributor, 16 a cooling water temperature sensor,
17 represents a knock sensor, and 18 represents an 1119 circuit.

Next, FIG. 2 is a block diagram illustrating the configuration of the control circuit 18. In the figure, 20, 21, and 22 are the air flow meter 10, the water temperature sensor 16, and the intake air temperature sensor 11, respectively.
23 is a multiplexer that selectively outputs the output signal of each buffer; 24 is an A/D converter that digitizes the analog signal output from the multiplexer 23; 25 is the multiplexer 23;
26 is a cylinder input/output port that outputs the control signal of the /D converter 24 and inputs the signal of each sensor 10116.11 via the buffer, 20.21.22 multiplexer 23, and A/D converter 24. A shaping circuit that shapes the waveform of the pulse signal output from the discrimination sensor 14 and the rotation angle sensor 15; 27 a knock discrimination circuit that discriminates whether there is knocking based on the signal output from the knock sensor 17; 28 a shaping circuit 26; The output signals of the cylinder discrimination sensor 14 and the rotation angle sensor 15 and the output signal of the knock sensor 17 are inputted via the knock discrimination circuit 27, and the mask signal of the knock discrimination circuit 27 is output. Each represents an output port. Note that the knock discrimination circuit 27 is 7k, which is not shown below.
A band pass filter that passes only signals in a frequency band around Hz, a rectifier circuit that half-wave rectifies the output of the band pass filter, an integration circuit that integrates the output of the rectifier circuit and creates a comparison reference value signal, and an output of the rectifier circuit. It consists of a comparator that compares the output of the integrating circuit, and outputs a knock detection signal when vibrations exceeding a certain amplitude are detected. In addition, the mask signal output from the input/output port 28 is designed to prevent the knock discrimination circuit 27 from malfunctioning due to noise such as vibration caused by the operation of the intake valve 6 and exhaust valve 4.
The knock discrimination circuit 27 is masked within a predetermined crank angle range.

29 is a drive circuit that operates the igniter 12 based on a signal output from the MPU 33, which will be described later, and 30 is a drive circuit! 829 is an output port that outputs signals from the MPU 33; 31 is a radial access memory (hereinafter simply referred to as RAM) in which data calculated based on the signals output from each sensor is stored; 32 is a control program and a A read-only memory (hereinafter simply referred to as ROM) in which necessary initial data is stored; 33 is a microprocessor unit (hereinafter simply referred to as MPU) that performs input/output of various signals, data calculations, and control of the drive circuit according to the control program in ROM 32; ), 34 includes MPU 33 and R
A clock circuit 35 outputs a clock signal that is a timing signal for each element such as the OM 32 and the RAM 31, and a path line 35 connects each element and serves as a data transfer path.

Furthermore, FIGS. 3 and 4 are flowcharts representing control programs.

The third s shows the main program of this embodiment. Each step will be simply explained below.

Reference numeral 101 represents a step .:)'I for initially setting the input/output board to a state necessary for starting the engine.

Reference numeral 102 represents a step of clearing the RAM 31 in which a flag Fk, etc., which will be described later, is stored, and setting initial data in registers, etc. in the RAM 31.

Reference numeral 103 represents a step of defining input/output counter ratios, such as setting a timing cycle for A/D conversion.

Reference numeral 104 represents a step for performing interrupt linkage set processing such as specifying a save destination address for saving the contents of the program counter, registers, etc. when an interrupt occurs.

105 represents a step of performing processing for permitting an interrupt when an interrupt signal is detected.

106 is the intake air amount Q per engine unit am from the air 70-meter 10 and rotation angle sensor 15.

Engine rotation speed N1 represents the step of calculating the intake air amount Q/N per engine rotation, which indicates the engine load.

Reference numeral 107 represents a step of calculating the basic advance angle value θB from the data map from the engine speed N1 and the engine load Q/N.

The main program composed of the steps described above performs the following processing.

First, when a key switch (not shown) is input, the control circuit 18 is activated, executes step 101 to set the input/output ports 25, 28, and 30 to the initial state, and then executes step 102 to store the RAM 31. After clearing and setting initial data, the input/output counter clock is defined in step 103, and step 104.1
After performing the processing necessary for interrupt processing in step 05, the engine rotation speed N1 necessary for ignition timing control is determined in step 106.
The engine load Q/N is calculated from the battler air IQ and the N and Q, and then in step 107, the basic advance value θB is determined from the data map based on the engine rotation speed N1 and the engine load Q/N. The processes of steps 103 to 107 are then repeated until the key switch is turned off.

In addition, FIG. 4 shows B of ignition timing control, which is the main part of this embodiment.
TDC (Before Top Dead Center)
This shows a 90° interrupt routine (before top dead center).Each step will be explained below.

Reference numeral 201 indicates the basic advance angle value θB obtained in the main routine, the intake temperature correction value θA calculated based on the intake temperature data obtained from the intake air filter sensor 11, and the water temperature sensor 16.
This represents the step of adding the water temperature correction value θW calculated based on the obtained water temperature data to calculate the advance angle required by the engine when using a high-octane engine, that is, the required advance angle value θ.

202 represents a step of determining whether or not a flag Fk indicating that the regular ignition timing has been corrected has been set since the engine was started.

203 represents a step of determining whether the engine rotation speed N is 1500 rotations or more.

204 represents a step of determining whether the engine rotation speed N is 4000 rotations or less.

Reference numeral 205 represents a step in which the knock sensor determines whether or not a knock detection signal is output from the knock determination circuit.

206 is the required lead angle value θ calculated in step 201
This represents a step of performing processing for further delaying Δθ for regular use.

207 represents a step of performing processing to set or maintain the flag Fk at "1".

The processing operation of this routine constituted by each step described above will be explained below.The BTDC90 of each cylinder determined by the cylinder discrimination sensor 14 and the rotation angle sensor
At the timing ', the MPLJ33 moves to execute the processing shown in this routine, and first in step 201, the basic advance angle θB calculated in the main routine described above is converted into the intake l0
A required advance angle value θ is corrected in accordance with TA and engine water temperature TW, and then in step 202 it is determined whether the flag Fk is set. In this step 202, a knock signal is detected from the start of the engine to the current time, and if the flag Fk is set, a determination is made to automatically switch to the regular ignition timing.

If the determination result of step 202 is rYEsJ, that is, flag Fk = 0, step 203 is executed, and it is determined whether the engine speed N exceeds the lower limit value, and if it exceeds the lower limit value, the determination result is Then, step 204 is executed. Note that step 203
The reason for setting the lower limit value is that even if high-octane engine is used, knocking is likely to occur in the low engine speed range, especially under high load, and knocking is easily detected in such low speed ranges. However, it is better not to switch to the regular ignition timing. Further, the reason why the upper limit value is set in step 204 is that vibration noise is large in the high engine speed range, making it impossible to accurately detect a knock signal. Therefore, in order to obtain an accurate knock detection signal, for example 1
The knock determination process in the next step 205 is performed only within the engine rotation range from 500 rpm to 400 OrD-.

Therefore, in steps 203 and 204, the engine speed N
If the value deviates from the specified range, the judgment result is rNO.
J, the processing of this routine is completed as it is, and if the determination result is rYEsJ, that is, the engine speed is within a predetermined range, the next step 205 is executed. In addition, during transient times such as acceleration or sudden negative thrust, knocking is likely to occur even at the normal advance angle, so it is better not to perform a knock judgment when the negative pressure of the intake manifold is below a predetermined value. More accurate knock detection is possible.

Then, in step 205, it is determined via the knock determination circuit 27 whether or not the knock sensor 17 has detected a knock, and if no knock has been detected, the determination result is f'N.
OJ is reached, and the process of this routine is immediately finished. If the determination result is "YES", that is, a knock has occurred, the process moves to step 206.

In step 206, processing is performed to delay the required advance value θ calculated in step 201 by Δθ, that is, processing to correct the high-octane ignition timing to the regular ignition timing. The value of the correction amount Δθ may be fixed to the average value or the maximum value of the difference between the required advance angle values in all driving ranges for high-octane and regular use. The value may be calculated according to a function based on the engine speed N as shown in the broken line and in FIG. In this embodiment, in order to obtain a more appropriate ignition timing, for example, the engine negative I as shown in FIG.
The correction amount Δθ is determined from a data map showing the difference between the required advance angle values for high-octane and regular use, which is stored in advance in the ROM 32 in correspondence with Q/N and engine speed N.

Then, in step 207, the value of the flag Fk is set to "
1" and completes the processing of this routine. Once the ignition timing for high-octane vehicles has been corrected to the ignition timing for regular vehicles in the above process. When the subsequent processing of this routine is performed, the required advance angle value θ is calculated in step 201, and then in step 202, the flag Fk is set to "
1", the process of step 206 is immediately executed, and the correction of the ignition timing for the regular engine is performed.
In the following step 207, the 7 lag Fk is maintained at "1", and the processing of this routine ends.

To summarize the processing of this routine described above, BTD09
The processing of this routine starts at a timing of 0°, the ignition timing for high-octane engine is calculated in step 201, and then it is determined by the flag Fk whether or not the ignition timing has been corrected before. If it is determined that the ignition timing has been performed, the process jumps to step 206 and maintains the process of correcting the ignition timing to the regular ignition timing. If no correction has been made yet, it is determined in steps 203 and 204 whether or not the engine speed N is within a range suitable for knock detection, and then in step 205 it is determined whether or not there is knock.
Only when the engine speed is within a range suitable for knock detection and knock is detected, the high-octane ignition timing is corrected to the regular ignition timing, and in the subsequent process a flag Fk is set, and the engine speed If the number is not suitable for detecting a knock, or if no knock is detected, the process of this routine ends.

In this way, once the flag Fk is set to "1", control is performed based on the ignition timing for the regular engine until the engine is stopped, so the ignition timing for the regular engine and the high-octane engine are controlled as in the conventional method. Regular, no folds required by switch operation.

There are no inconveniences caused by using high-octane fuel with the ignition timing still set.

In the interrupt routine of the BTDC906, a timekeeping step is provided in which Fk is first set at step 207 and reset after a predetermined period of time, for example, 1 to 2 hours. If you reset it, even if for some reason, for example, a deposit occurs in the combustion chamber, or the air-fuel ratio suddenly becomes lean, knocking occurs and the ignition timing is incorrectly corrected to the regular ignition timing. After a predetermined period of time has elapsed, it is possible to determine again whether or not the ignition timing can be corrected based on the fuel used.

As detailed above, the method of the present invention performs ignition timing control based on a preset required advance value for octane fuel (high octane fuel), and when engine knock is detected under predetermined engine conditions, ignition timing is controlled. The ignition timing is corrected to the retarded side, and after the correction, the ignition timing correction 5 is continued until the engine stops or a certain period of time elapses.
It is characterized by continuing 11 luck.

Therefore, when engine knock is detected under specified engine rotation conditions, it will automatically determine that the fuel in use is not high-octane without any troublesome manual operation, and will continue to operate until the engine stops or for a certain period of time. The ignition timing is controlled using the required advance value for regular use until .

Therefore, frequent occurrence of harsh knocking noises and damage to the engine can be prevented, and ignition timing can be controlled according to the fuel used.

It has an effect.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an engine and its peripheral equipment applied to an embodiment of the method of the present invention. Fig. 2 is a block diagram showing the same control circuit, Fig. 3 is a flowchart showing the main program of the embodiment, Fig. 4 is a flowchart showing the BTD090° interrupt routine, and Fig. 6 is the engine rotation for high-octane and regular use. Figure 6 is a graph showing the required advance angle correction amount according to the engine speed, that is, the difference between the required advance angle values for high-octane and regular use. This is a data map showing the required advance angle correction amount corresponding to the load-engine speed. 1... Engine 5... Spark plug 10... Air 70 Meter 11... Intake temperature sensor 14... Cylinder discrimination sensor 15... Rotation angle sensor 16... Water temperature sensor 17... Knock Sensor 18...Control circuit 33...MPLJ Agent Patent attorney Tsutomu Sadatetsu Figure 3 Figure 4 Figure 5 Figure 7

Claims (1)

[Claims] 1 Ignition timing is controlled according to a preset required advance value for off-octane fuel, and when engine knock is detected under predetermined engine conditions, the ignition timing is changed between the required advance value and normal octane fuel. The ignition timing correction process is performed to retard the ignition timing according to the difference between the required advance value and the ignition timing correction process. Features 13111 methods of ignition timing.