JPS6229764A - Ignition timing control method for internal-combustion engine - Google Patents

Abstract

PURPOSE:To improve the operating performance and fuel consumption by limiting correction through learning correction level of ignition timing on the basis of upper limit delay angle when said correction is to further delay angle side than predetermined upper limit delay angle. CONSTITUTION:When the operating condition is within specific range, the ignition timing is corrected (C2) on the basis of a learning correction level. While when it is at the outside of said range, the ignition timing is corrected (C3) on the basis of said learning correction level. The upper limit of delay angle when the operating condition is at the outside of specific range is predetermined, and when the correction of ignition timing based on said learning correction level is further to the delay side than said upper limit, correction through learning correction level of said ignition timing is limited (C4) on the basis of said upper limit. In such a manner, the operating performance and fuel consumption can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an ignition timing control method for an internal combustion engine, and more particularly to an ignition timing control method that performs ignition timing control in accordance with the octane number of fuel.

[Prior art] In recent years, as air pollution regulations have been tightened, the use of high-octane fuels containing lead compounds such as tetraethyl lead has been restricted. However, considering the output efficiency of internal combustion engines, it is necessary to increase the compression ratio. High octane fuel 11 is more advantageous, and high octane fuel that does not contain lead compounds has recently been developed, and high octane fuel and normal octane fuel have recently coexisted as fuel for internal combustion engines.

If normal octane fuel (hereinafter simply referred to as regular) is mistakenly used in an engine designed to use high octane fuel (hereinafter simply referred to as high-octane fuel), or if high-octane fuel is not available and regular is unavoidably used. In addition, the engine is unable to fully demonstrate its performance, and engine knocking (hereinafter simply referred to as knocking) occurs frequently, 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 the regular, the ignition timing for regular is specified by operating a switch, and the ignition timing is delayed. A method has been proposed in which the engine is protected by changing the engine to the corner side, and a method having an ignition timing map for a predetermined octane number, detecting knocking, and automatically correcting the ignition timing of the map in accordance with the octane number of the fuel.

The latter ignition timing control method is preferable because it does not require complicated switch operations and can achieve complete automation of ignition timing control.

Such an ignition timing control method usually has a high-octane ignition timing map, and searches for the basic ignition timing based on, for example, internal combustion engine speed and intake pipe negative pressure, as well as detects knocking in the internal combustion engine and detects knocking. If it occurs frequently, that is, if it is in regular operation, the system learns the knocking occurrence situation at that time and corrects the optimum retardation width from the basic ignition timing to ensure the best operating condition for the internal combustion engine. That's what I do.

[Problems to be Solved by the Invention] However, the ignition timing control method as described above also has the following problems and is still not satisfactory.

In other words, the knocking sensor that detects knocking in an internal combustion engine detects mechanical sounds and vibrations that occur when the engine is operating, but when the internal combustion engine is operated at high rotational speeds, the Even if there is, mechanical noise, vibration, etc. increase, so-called background noise increases, and knocking detection accuracy decreases.

For this reason, in the conventional method described above, if the ignition timing retard width based on the above-mentioned knocking detection results is calculated as a learning correction value in the low- and medium-speed range of the internal combustion engine, Sometimes, a method is adopted that uses the learning correction value as is.

was used.

However, as shown in Figure 2, which shows the relationship between the rotational speed of the internal combustion engine and the ignition timing, the ignition timing immediately before the output torque of the internal combustion engine reaches a flat shaft torque (hereinafter simply referred to as the MBT point)
On the other hand, the ignition timing at the point where knocking occurs when using a high-octane engine or a Regi 1 engine is a function of the rotational speed and does not show a uniform change. Therefore, although it is possible to control the optimal ignition timing in periods where appropriate learning control is performed, such as in the low and medium speed ranges of an internal combustion engine, it is useless in high speed ranges where the learning correction value at that time is used as is. The retardation causes a decrease in the output of the internal combustion engine, and depending on the extent of the unnecessary retardation, there is a possibility that fuel efficiency and emissions may deteriorate.

The present invention was made in view of the above-mentioned problems, and is an excellent internal combustion engine that can automatically determine the octane of fuel in the entire rotation range of the internal combustion engine and operate the internal combustion engine under the optimum ignition timing. Its purpose is to provide a method for controlling ignition timing.

[Means for Solving the Problems] In order to solve the above problems, the means configured in the present invention detects the operating state of the internal combustion engine, as shown in the basic configuration diagram of FIG. When the operating state of the internal combustion engine is within a predetermined range, the ignition timing of the internal combustion engine is controlled based on the ignition timing determined in advance assuming a predetermined octane conversion, and the learning that learns the operating state of the internal combustion engine at this time. Correctly correcting the ignition timing using a correction value (C2); when the operating state is outside the predetermined range, correcting the ignition timing using the learned correction value (C3); A retard upper limit value of the ignition timing when the operating state is outside the predetermined range is predetermined, and when the ignition timing correction based on the learning correction value is on the retarded side than the retard upper limit value, the retard upper limit value is used. The gist of the present invention is an ignition timing control method for an internal combustion engine, which is characterized in that correction of the ignition timing using a learned correction value is limited (C4).

[Function] The restriction (C4) on correction of ignition timing using a learning correction value in the present invention refers to the following effect.

The operating characteristics of an internal combustion engine are determined at the time of designing the internal combustion engine itself, and the conditions for optimal operation can be determined theoretically or experimentally in conjunction with the load driven by the internal combustion engine, such as a transmission. becomes. Ignition timing is no exception, and it is easy to determine the optimum ignition timing based on the internal combustion engine and its load. Therefore, as a predetermined upper limit value of retardation, the maximum retardation value is theoretically or experimentally determined, such as when low-octane fuel is used in the internal combustion engine.

When an internal combustion engine is operated accurately under learning control,
Since the learning correction value is determined from the history of the actual operating state of the internal combustion engine, the control may be prioritized, but in the region where the learning control is not possible, complete absorption control is performed.

Therefore, in the case of ignition timing control outside the predetermined range where learning control is determined to be impossible, priority is given to the retardation upper limit value determined as described above, and retardation control beyond this value is guarded.

In determining the upper limit value of retardation, the upper limit value of retardation is determined according to the rotational speed of the internal combustion engine, since there is a close relationship between ignition timing and engine speed as described above in Figure 2. It is preferable to define Further, as a normal ignition timing control, it is well known that the ignition timing is appropriately advanced or retarded from the MBT point in order to give top priority to characteristics such as emissions, but the present invention can also be combined with these controls. For example, it is also possible to prepare a plurality of retardation upper limit values that give priority to characteristics such as emissions, and select one as appropriate for use as a guard.

EXAMPLES In order to explain the present invention more specifically, the present invention will be described in detail with reference to Examples.

[Example] First, FIG. 3 is an explanatory diagram showing an engine and its peripheral devices to which the ignition timing control method of the example is applied. In the figure, 1 is the engine body, 2 is the piston, 3 is the exhaust manifold, 4 is the exhaust valve, 5 is the spark plug, 6 is the intake valve, 7 is the intake manifold, 8 is the fuel injection valve, 9 is the throttle valve, and 10 is the 1 is an air flow meter, 11 is an intake temperature sensor, 12 is an igniter, 13 is a distributor, 14 is a rotational speed sensor provided in the distributor and also serves as a cylinder discrimination sensor; 1
5 is a rotation angle sensor also provided in the distributor, 16 is a cooling water temperature sensor, 17 is a knock sensor,
And 18 each represents a control circuit.

Next, FIG. 4 is a block diagram illustrating the configuration of the control circuit 18. In the figure, 20, 21 and 22 are air flow meters 10. Water temperature sensor 16, intake temperature sensor 11
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, and 25 is a multiplexer 23 . A
Input/output port 26 that outputs the control signal of the /D converter 24 and inputs the signals of each sensor 10, 16.11 via the buffer, 20.21.22 multiplexer 23, and A/D converter 24; 27 is a shaping circuit that shapes the waveform of the pulse signal output from the rotation speed sensor 14 and the rotation angle sensor 15; 27 is a knock discrimination circuit that determines whether there is knocking based on the signal output from the knock sensor 17; and 28 is a shaping circuit. Inputting the respective output signals of the rotation speed sensor 14 and the rotation angle sensor 15 via the circuit 26 and the output signal of the knock sensor 17 via the knock discrimination circuit 27,
and the input/output where the mask signal of the knock discrimination circuit 27 is output.
Each represents an output port. Note that the knock discrimination circuit 27 includes a bandpass filter that passes only signals in a frequency band around 7KH2, which is most likely to occur as knocking in this system, a rectifier circuit that half-wave rectifies the output of the bandpass filter, and a rectifier circuit. It consists of an integrator circuit that integrates the output of the integrator and generates a comparison reference value signal, and a comparator that compares the output of the rectifier circuit and the output of the integrator 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 transmitted to the intake valve 6 and the exhaust valve 4.
The knock discrimination circuit 27 is masked within a predetermined crank angle range to prevent the knock discrimination circuit 27 from malfunctioning due to vibrations caused by the operation of the crankshaft and ignition noise.

Further, 29 is a drive circuit 30 that operates the igniter 12 based on a signal output from the MPLJ 33, which will be described later.
3 is an output port that outputs signals from the MPU 33 to the drive circuit 29; 31 is a random 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 read-only memory (hereinafter simply referred to as ROM) stores initial data necessary for control, and 33 inputs and outputs various signals according to the control program in the ROM 32.

34 is a microprocessor unit (hereinafter simply referred to as MPtJ) that performs data calculations and controls the drive circuit.
A clock circuit outputs a clock signal that is a timing signal for each element such as the PU 33, ROM 32, and RAM 31, and 35 represents a path line that connects each element and serves as a data transfer path.

Further, FIG. 5 shows a flowchart for controlling the ignition timing of this embodiment. In FIG. 5, 110 represents an initialization step in which the number of determinations n is set to O. 1
20 is whether the conditions for determining the presence or absence of knocking are satisfied in the internal combustion engine, that is, the engine speed Nc is 4200 revolutions or less, and Q/Ne, which represents the amount of intake air per engine revolution, is satisfied. 0.75Q/rev
or more, and the engine cooling water mTw is 70°C or more and 95°C
This represents the step of determining whether or not the above conditions hold true. Reference numeral 130 represents a process of setting the engine's ignition timing to the determination advance angle θj for determining the octane number of the fuel. 140 represents a step of determining whether knocking has occurred. 145 is a step of detecting one revolution of the engine, 150 is a step of incrementing n, which represents the engine speed after starting the process of determining the octane number, by 1, and 160 is a step when the engine speed n reaches 30. This represents the step to determine whether the goal has been reached. Step 170 is a step of decrementing the parameter L representing electrification and incrementing the number of times M for determining the octane number of the engine, and step 180 is a step of searching the ignition timing map for high-octane ignition timing of the engine. The reference ignition timing θhO is determined by using the learning correction value θk (L), which is a function of the parameter L representing the octane conversion, and the ignition timing θi is calculated using the following formula.
is calculated.

θi=θhO−θk (L) 190 represents a process for determining the time t (hereinafter referred to as interval time) until the next octane number determination is performed, and in this embodiment, it is given by t=MX2400/Ne. Further, step 200 represents the process of incrementing the octane conversion parameter L with the number of determinations M of the octane number of the fuel to 1 together with Cera1. Steps 300 to 320 are learning of ignition timing θi@
This is executed when the engine is running at high speed, which is out of range, and in step 300, θG is searched from the guard retard amount map that determines the upper limit of the retard amount, and in step 310, the learning correction amount θk (L) is determined. A comparison is made with the above-mentioned θG, and in step 320, processing is executed to match the contents of θk (L) with θG.

6 and 7 are explanatory diagrams of maps used in the flowchart of FIG. 5 above. First, Figure 6 shows how far to advance a certain ignition timing to obtain the optimal reference ignition timing θhO for high-octane engine based on two pieces of information, such as engine speed and intake pipe negative pressure, from the engine operating state. This is a three-dimensional ignition advance angle map for determining the optimum reference ignition timing θho when using high-octane fuel based on the operating state of the engine. Furthermore, FIG. 7 is a map of the guard retard angle θG, which is defined only on the high speed side of the engine. As shown in the figure, the maximum value of the amount of retardation determined theoretically or experimentally at the time of designing the engine system at a rotation speed of 4200 [ROM1 or more] is expressed as a two-dimensional map with the rotation speed.

Next, the processing in this embodiment will be explained using FIGS. 5 to 7. This processing routine is activated every time an interval time (to be described later) elapses, enters from A, and first, in step 110, parameters necessary for the processing of this embodiment are initialized, that is, n=O. In the subsequent step 120, the engine rotational speed Ne is read by the rotational speed sensor 14, the intake air ff1Q is read by the air flow meter 10, and the engine cooling water temperature TW is read by the cooling water temperature sensor 16, and the operating state of the engine determines the conditions for determining the octane number. Determine whether the requirements are met. In this example, the conditions for determining the octane number are that the engine speed No. is 4200 revolutions or less, and the intake air amount per engine revolution is 0.7Q/re.
v or more, and the engine cooling water temperature TW is 70'C or more and 95C or less. Step 12
If the judgment at 0 is 1No, that is, the octane number judgment condition is not satisfied, the process proceeds to step 30, which will be described later.
Move after 00. The determination at step 120 is “YES”.
'', that is, if the octane number determination condition is satisfied, the process moves to step 130, and the engine ignition timing is changed to the octane number determination advance angle θj, which will be described later. The following step 140 is
This is a detection process to determine whether knocking occurs during operation at ignition timing θj. The initial value of the octane number determination advance angle θj in step 130 is further advanced than the reference ignition timing θhO calculated as described above using the map shown in FIG. Knocking cannot occur if high octane is used during operation, but knocking always occurs when regular is used. In this way, step 13
The ignition timing θj set at 0 is used to detect knocking, but if knocking is detected frequently at this time, the advance angle can be adjusted using the following formula using the variable that becomes the octane number parameter described later. The degree is reduced;
To avoid unnecessary knocking in an engine.

θj=θj−Δθj−L If knocking is detected in step 140, the process moves to step 200, where a parameter M representing the number of times octane number determination has been performed is set to 1, and a parameter L for octane number determination is incremented. The process then proceeds to step 18O, which will be described later. Step 14
If the determination as to whether there is knocking at 0 is "YES", that is, if there is no knocking, the process moves to step 145, and it is determined based on the signal from the rotation speed detection sensor 14 whether or not the engine has rotated once. If the engine has not made one rotation, the process returns to step 140 and detects whether or not there is knocking again. If it is determined in step 145 that the engine has rotated once, the process moves to step 150, where a parameter n representing the engine rotational speed is incremented by 1. In the following step 160, it is determined whether the engine speed n has reached a value preset as the number of determinations, 30 in this case. In this case, the engine speed n represents the engine speed from when the ignition timing is determined as the octane number determination advance angle θj. If the engine speed does not reach 30 times in step 160, the process returns to step 140,
The presence or absence of knocking is detected again. If knocking is detected even once within 300 revolutions of the engine after the octane number determination begins, the process of step 200 described above is performed.

If knocking is not detected within 30 engine revolutions after the start of octane number determination, the process moves to step 170, where a parameter M representing the number of octane number determinations is incremented by 1 and a parameter L for octane number determination is decremented. In step 180, the ignition timing θhO for high-octane engine is determined using the map shown in FIG. It represents. The ignition timing for the high-octane engine is θho, which means that the advance angle value represented by the map in FIG. 6 is used. In the following step 190, the interval time t is determined. In this step, t is calculated as t = MX2400/Ne. That is, as the octane number is repeatedly determined, the time (interval time t) until the next octane number determination becomes longer, and conversely, as the engine speed Ne increases, the interval time t becomes shorter. This is because if the octane number of the fuel is repeatedly determined, the reliability of the determination regarding the octane number of the fuel will be high, so it is not necessary to perform this determination as frequently, and on the other hand, if the engine is operated at high revolutions. This means that the interval time t is set so that the octane rating is determined more frequently as the engine speed increases, since the occurrence of knocking when the engine speed is high is likely to cause serious consequences such as engine damage.

As described above, the ignition timing is based on the high-octane θho under predetermined operating conditions, and is controlled optimally by learning control even when the regular engine is in use. On the other hand, ignition timing control when the operating conditions are outside the above, which is a feature of this embodiment, is performed as follows. First, in step 300, which is executed when it is determined in step 120 that the above operating conditions are not met, the guard retard amount θG is searched from the current engine rotation speed using the map shown in FIG.
At step 10, a comparison is made in magnitude with the learning correction value θk (L) obtained at step 180 described above.

That is, the learning correction value θk calculated under the above operating conditions
It is determined whether the retard angle control using (L) is larger than the theoretically or experimentally determined guard retard amount at high engine speed. As explained using Fig. 2, the optimum ignition time is not of the nature that it is sufficient to retard the ignition to a uniform rate over the entire rotation speed range; There are cases where it is inappropriate to use the correction value θk (L) as it is, and this state is detected. Therefore θG
If θk (L), the guard process is performed in step 32 to once match the value of θk (L) with the guard retard amount θG.
If θG≧θk (L), the process directly proceeds to step 180 described above to calculate the ignition timing θi.

In this embodiment, it is configured to determine whether or not operating conditions that enable the determination of the octane number are established, and to set the ignition timing at a determination advance angle θj to detect the occurrence of knocking. There is. Therefore, if the operating condition meets the octane number judgment conditions, it will determine whether the fuel is high-octane or regular and determine the optimal ignition timing, so no matter which fuel is used, the engine will always be in the best operating condition. Secured. Furthermore, when the engine speed increases and the octane conversion determination condition is no longer satisfied, the already learned learning correction value θk (L) is used to retard the ignition timing even at high engine speeds. However, if the learning correction value θk (L) is calculated to a value that retards the engine by a predetermined guard retard amount of 60 or more as the engine's maximum retard opening, guard processing using θG is performed. is executed.

Therefore, even if the engine is operating at high speeds with large background noise, the engine will not be retarded by more than the predetermined maximum retard amount, and the engine output will be unnecessarily lost at high speeds. avoids being exposed to This brings about the effect of sufficiently improving the operating performance of the engine even at high speeds, and also resulting in an extremely excellent ignition timing control method that improves fuel efficiency.

In this embodiment, the guard retardation amount θG is searched using only the rotational speed as a parameter, but it may be configured to be determined with higher accuracy than a multidimensional map or calculation formula that incorporates other factors such as the water temperature of the engine.

[Effects of the Invention] As described above in detail with reference to the embodiments, the ignition timing control method for an internal combustion engine of the present invention includes: detecting the operating state of the internal combustion engine; and when the detected operating state is within a predetermined range; The ignition timing of the internal combustion engine is controlled based on the ignition timing determined in advance assuming a predetermined octane conversion, and the ignition timing is corrected using a learning correction value learned from the operating state of the internal combustion engine at this time. In the ignition timing control method for an internal combustion engine, which corrects the ignition timing using the learned correction value when the operating state is outside the predetermined range, A value is determined in advance, and when the correction of the ignition timing by the learning correction value is on the retarded side than the retardation upper limit value, the correction of the ignition timing by the learning correction value is limited by the retardation upper limit value. It is something.

Therefore, the ignition timing control that best suits the characteristics of the internal combustion engine is executed, and unnecessary ignition timing retard control in the high rotation range is avoided.

This means that the output of the internal combustion engine can be prevented from decreasing in the high speed range, and the operating performance of the internal combustion engine can be further improved. Furthermore, the present invention has significant effects such as improved fuel efficiency since there is no needless fuel consumption.

[Brief explanation of the drawing]

Fig. 1 is a basic configuration diagram of the present invention, Fig. 2 is an explanatory diagram of changes in ignition timing with respect to the rotational speed of the internal combustion engine, and Fig. 3 is an internal combustion engine and its peripheral equipment to which the ignition timing control method of the embodiment is applied. 4 is a block diagram illustrating the configuration of the control circuit, FIG. 5 is a flowchart illustrating the processing of the embodiment, and FIG. 6 is an explanation of the three-dimensional map used to calculate the ignition timing in the embodiment. FIG. 7 shows an explanatory view of a two-dimensional map for searching the guard retard amount in the embodiment. 1... Engine body 10... Air flow meter 14... Rotation speed sensor 16... Cooling water temperature sensor 17... Knock sensor 18... Control circuit

Claims (1)

[Claims] Detecting the operating state of the internal combustion engine, and when the detected operating state is within a predetermined range, adjusting the ignition timing of the internal combustion engine based on the ignition timing predetermined assuming a predetermined octane conversion. and correcting the ignition timing using a learning correction value learned from the operating state of the internal combustion engine at this time, and when the operating state is outside the predetermined range, correcting the ignition timing using the learned learning correction value. In the ignition timing control method for an internal combustion engine, an upper limit value of retardation of the ignition timing when the operating state is outside the predetermined range is determined in advance, and the correction of the ignition timing by the learning correction value is lower than the upper limit retardation value. An ignition timing control method for an internal combustion engine, characterized in that when the ignition timing is on the retard side, correction of the ignition timing by the learned correction value is limited by the retard upper limit value.