JP2734056B2 - 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 more particularly to an ignition timing control device for an internal combustion engine provided with a knocking control system having a learning function.

[Problems to be solved by conventional technology and invention]

BACKGROUND ART Conventionally, an ignition timing control device including a knocking control system that detects whether or not knocking, which is an air column vibration generated due to self-ignition of an end gas in a cylinder, and controls the knocking has been known. . In this ignition timing control device, the ignition advance angle obtained by subtracting the correction retardation amount calculated from the basic ignition advance angle so as to increase when knocking occurs and to decrease when knocking does not occur is used. When knocking occurs, the ignition timing is retarded, and when knocking does not occur, the ignition timing is advanced to control the ignition timing to the maximum advancement (knocking limit) where no knocking occurs (for example, Japanese Utility Model Laid-Open No. 57-92074, Japanese Unexamined Patent Publication No. Sho 6
Publication No. 0-26172).

The basic ignition advance angle is set to a required value (MBT) under conditions (water temperature, weather conditions, etc.) where fuel having the highest octane number is used and knocking is unlikely to occur. For this reason,
When using fuel with a low octane number or under conditions where knocking is likely to occur, the ignition timing cannot be controlled by the basic ignition advance, and knocking is more likely to occur at higher loads. The lower the load, the higher the load. Therefore, when the operating state is such that the knocking hardly occurs in the operating range (ignition timing outside the light load range or the knocking control range is MB
In the initial stage of transition from the region controlled on the T side to the operation region in which knocking is likely to occur (high load region or within the knocking control region), knocking occurs because the correction retardation amount is not sufficiently large. As a result, it becomes impossible to cope with a wide range of change in fuel octane number and a change in weather conditions. Further, when the operation state suddenly shifts from the high load region to the low load region in the knocking control region, the initial ignition timing is excessively retarded because the correction retardation amount is not sufficiently small at the initial stage, and the fuel consumption is reduced. Worsens. For this reason, JP-A-60-26172 and JP-A-61-619
No. 68 discloses an ignition timing control device incorporating a learning function. The ignition timing control device incorporating the learning function sets a learning value in advance for each of a plurality of operating regions (learning regions) and updates the learning value in that region according to the magnitude of the correction retardation amount. Is stored, and this learning value is reflected in the ignition timing control when the operating condition enters the region thereafter.

However, in the above-described conventional technique, it is necessary to set a learning value for each learning region, so that the number of learning values is large,
There is a problem that a large memory area is required. This problem can be solved by reducing the number of learning areas and reflecting the learning value in the control of the driving area outside the learning area. Japanese Patent Application Laid-Open No. 60-224956 discloses that the degree of reflection depends on the number of times of learning. Is changed to reflect the learning value of the current operation state in the control of another operation state. However, when the operation frequency in the light load range is high, the learned value in the light load range is reflected in the ignition timing control in the high load range, and the learned value in the light load range becomes the learned value in the high load range. On the other hand, there is a problem that the error is large (the correction retard amount is large as the load is high and the correction retard amount is small as the load is low), so that the ignition timing control accuracy is deteriorated.

Note that, in order to prevent excessive retardation and overadvancement due to a knocking sensor file or the like, the ignition timing control device generally limits the correction retardation amount to a value within a predetermined range. JP-A-54-109529).

The present invention has been made in order to solve the above-described problem, and it is possible to reduce the number of learning values to reduce the memory area, and to reduce an error when the learning values are reflected in control outside the learning area. It is an object of the present invention to provide an ignition timing control device for an internal combustion engine that is prevented from generating.

[Means for solving the problem]

In order to achieve the above object, the present invention provides a knocking detecting means A for detecting occurrence of knocking, as shown in FIG. 1, and a method for delaying the ignition timing when knocking occurs and no knocking occurs. A retard amount calculating means B for calculating a corrected retard amount for advancing the ignition timing; and a learning value for setting the corrected retard amount to a value within a predetermined range in an operating region where knocking is most likely to occur. , A load detecting means D for detecting the engine load, a correcting means E for correcting the learning value so as to decrease as the engine load decreases, and a limit value within the operating range. Limiting means F for limiting the amount of correction retardation so that
And controlling the ignition timing by reflecting the learning value calculated by the learning value calculating means C and the correction retardation amount limited by the limiting means F within the operating region, and controlling the ignition timing outside the operating region. The ignition timing control means G controls the ignition timing by reflecting the learning value corrected by the correction means E and the corrected retardation amount calculated by the retardation amount calculation means B. .

[Action]

Next, the operation of the present invention will be described with reference to FIG. The retard amount calculating means B is for delaying the ignition timing when knocking occurs and for advancing the ignition timing when no knocking occurs based on the output of the knocking detecting means A for detecting the occurrence of knocking. Calculate the correction delay amount AKCS. The learning means C calculates a learning value KCSKG for setting the corrected retardation amount AKCS to a value within a predetermined range in an operation region where knocking is most likely to occur. The operating region in which this knocking is most likely to occur is usually the region near the full load including the throttle valve fully opened (full load). In this operation region, the correction retardation amount AKCS has a large value, so that the learning value KCSKG also has a large value. The correction means E provides a learning value KCSK such that the load detected by the load detection means D decreases as the load decreases.
Modify G. The restricting means F controls the corrected retard amount AK so that it is within the limit value within the operating range where knocking is most likely to occur.
Restrict CS. The ignition timing control means G controls the ignition timing by reflecting the uncorrected learning value and the limited correction retard amount in the operating region where knocking is most likely to occur,
Outside the operating region where knocking is most likely to occur, the ignition timing is controlled by reflecting the corrected learning value and the unrestricted corrected retard amount.

In the driving region where knocking is most likely to occur, learning is performed with the retard amount limited. Outside the driving region where knocking is most likely to occur, the learning value corrected as described above according to the load without setting a learning value. Is reflected, the number of learning values can be reduced, and the error of the reflected learning value with respect to the required learning value can be reduced. Also,
Since the unrestricted correction retard amount is reflected, even if an error occurs between the ignition timing and the required value due to the reflection of the corrected learning value, the error can be absorbed.

〔The invention's effect〕

As described above, according to the present invention, the learning value learned in the driving region where knocking is most likely to occur is corrected and reflected in other driving regions, and the correction delay amount is increased in other driving regions. Since the control range of the knocking is widened so as not to limit the control value, the effect that the controllability of the knocking can be improved without increasing the memory for storing the learning value is obtained.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 2 shows an example of an internal combustion engine (engine) provided with an ignition timing control device to which the present invention can be applied.
Distributor of 4-cycle 6-cylinder gasoline engine 10
A cylinder discriminating sensor 16 and a rotation angle sensor 18 each comprising a signal rotor fixed to a distributor shaft and a pick-up fixed to a distributor housing are mounted on the unit 14. Cylinder identification sensor
No. 16 generates one pulse every time the distributing shaft makes one rotation, that is, every time the crankshaft makes two rotations (720 ° CA (crank angle)). The position where this pulse is generated is, for example, the top dead center (TDC) of the first cylinder. The rotation angle sensor 18 generates, for example, 24 pulses each time the distribution shaft rotates once, and thus generates one pulse every 30 CA. Cylinder discrimination sensor 16 and rotation angle sensor 18
Is a control circuit including a microcomputer
Connected to 20.

A knocking sensor 12 constituted by a magnetostrictive element or the like for detecting engine vibration is attached to a cylinder block of the engine 10, and an electric signal output from the knocking sensor 12 is input to a control circuit 20. . A surge tank 11 is arranged downstream of the throttle valve 25 arranged in the intake passage 22, and a pressure sensor 24 for detecting an intake pipe pressure as an engine load is attached to the surge tank 11. The surge tank 11 is connected to a combustion chamber of the engine via an intake manifold. The combustion chamber of the engine is connected to a catalyst device (not shown) filled with a three-way catalyst via an exhaust manifold. The exhaust manifold is provided with an O ₂ sensor 32 that detects the concentration of residual oxygen in the exhaust gas and outputs a signal inverted at a value corresponding to the stoichiometric air-fuel ratio. Further, a water temperature sensor 30 for detecting the engine cooling water temperature is mounted so as to penetrate the cylinder block and protrude into the water jacket. On the other hand, an ignition signal is output from the control circuit 20 to the igniter 26, and the high voltage generated by the igniter 26 is distributed by the distributor 14, and is supplied to an ignition plug 28 attached to each cylinder in order. Also,
The control circuit 20 is connected to open the fuel injection valve 29 for a time corresponding to the calculated fuel injection time to control the fuel injection amount. IG is an ignition switch.

The control circuit 20 includes a random access memory (RAM) having a backup RAM backed up with a power supply, a read only memory (ROM), and a microprocessing unit (MPU). The ROM 60 includes a control routine program described below, a correction coefficient K table (FIG. 4) for correcting the learning value so that the intake pipe pressure PM as the engine load decreases as the engine load decreases, and knocking. A basic ignition advance table (FIG. 6) and the like are determined in advance so that an MBT can be obtained when the fuel having the highest octane number is used under conditions that do not easily occur.
Further, the back-up RAM stores a learning value (initial value 0) corresponding to an operation region where knocking is most likely to occur, and the RAM stores a correction retardation amount (initial value 0).

FIG. 5 shows a graph at every predetermined crank angle (for example, 90 ° CA BTDC).
2 shows an ignition timing calculation routine executed every time. First, at step 100, the intake pipe pressure PM and the engine rotational speed NE are taken, and are determined as shown in FIG.
The basic ignition advance angle THIBS is calculated from the table stored in the ROM by the interpolation method. In the next step 102, the correction retardation amount AKCS and the correction learning value TKG are added to determine the retardation amount KCSRTD. The details of the correction delay amount AKCS and the correction learning value TKG will be described later. Then, in step 104, the effective ignition advance THT is calculated by subtracting the retardation amount KCSRTD from the basic ignition advance THIBS, and the igniter is turned on in advance in an ignition routine (not shown), and the crank angle is set to the effective ignition advance THT. At this point, ignition is performed by turning off the igniter.

Next, referring to FIG. 3, the correction delay amount AKCS and the correction learning value
A calculation routine such as TKG will be described. In step 110, it is determined whether or not the intake pipe pressure PM exceeds a predetermined value a to determine whether or not the current operating area is an operating area where knocking is most likely to occur. The operating region in which this knocking is most likely to occur is the region near the throttle valve fully open state including the throttle valve fully open state. In addition to the determination based on the magnitude of the intake pipe pressure PM as described above, it is turned on when the throttle valve is fully open. A switch may be mounted to make a determination based on the on / off state of the switch.

When the engine is in the driving range where knocking is most likely to occur,
In step 112, it is determined whether or not knocking has occurred by determining whether or not the A / D conversion value of the output of the knocking sensor 12 has exceeded the determination level. When it is determined that the A / D conversion value exceeds the determination level and knocking has occurred, the correction delay amount AKCS is increased by a predetermined value b in step 114, and when it is determined that knocking has not occurred, in step 116. The correction retard amount AKCS is reduced by a predetermined value c.
In step 118, it is determined whether or not the corrected retardation amount AKCS has exceeded the upper limit value α, and if so, the value of the corrected retardation amount AKCS is set to the upper limit value α in step 120, whereby the corrected retardation amount AKCS is determined.
In addition to limiting CS so that it does not exceed the upper limit α, the learning value
Increase KCSKG by a predetermined value d. On the other hand, in step 124,
It is determined whether or not the corrected retardation amount AKCS has become less than the lower limit value β, and if it is less than the lower limit value β, the value of the corrected retardation amount AKCS is set to the lower limit value β in step 126, whereby At the same time, the learning value KCSKG is reduced by a predetermined value e.

As a result, the corrected retard amount AKCS is limited to a value within a limit value where the upper limit is α and the lower limit is β, and the insufficient ignition timing retard angle caused by this limit increases or decreases the learning value KCSKG. Is compensated by doing so.

When the vehicle is outside the driving range where knocking is most likely to occur,
It is determined in step 130 whether or not knocking has occurred in the same manner as described above. If knocking has occurred, the correction delay amount AKCS is increased by a predetermined value b in step 132, and if no knocking has occurred, the correction delay amount is increased in step 134. AKCS
Is reduced by a predetermined value c. Outside the operating region where knocking is most likely to occur, the correction retard amount AKCS is not limited.

In step 136, a correction coefficient K is calculated from the table shown in FIG. 4 by an interpolation method based on the intake pipe pressure PM and the engine speed NE. Then, at step 138, the learning value KCSKG
Is multiplied by a correction coefficient K to obtain a corrected learning value TKG. As shown in FIG. 4, the correction coefficient K is set to 1 in the region of PM ≧ a, and is set to 1 in the region of PM <a.
When the intake pipe pressure PM is constant, it becomes smaller as the intake pipe pressure PM becomes smaller, and when the intake pipe pressure PM is constant, it becomes smaller as the engine speed NE decreases.
Therefore, the learning value is reflected in the ignition timing without correction in the region of PM> a (the region where knocking is most likely to occur), and in the region of PM <a, the intake pipe pressure PM and the engine speed NE
Is modified so that it becomes smaller in accordance with and reflected. Since the correction delay amount AKCS is not restricted outside the driving range where knocking is likely to occur, even if an error occurs between the correction learning value and the required learning value, the correction delay amount Can be increased or decreased to absorb this error.

As described above, according to the present embodiment, the entire range can be controlled by the ignition timing in accordance with the octane number of the fuel without increasing the memory, and the occurrence of knocking and the deterioration of fuel efficiency can be prevented. In particular, in the case of an LPG engine with a high compression ratio, the octane number of the fuel component (motor octane number) is 80 to 100.
The effect is great because it exists in a wide range.

In the above description, the engine that detects the intake pipe pressure as the engine load has been described. However, the present invention can also be applied to an engine that detects the intake air amount. Further, the correction coefficient K is determined according to the engine load and the engine speed, but may be determined only according to the engine load.

[Brief description of the drawings]

FIG. 1 is a block diagram corresponding to the claims of the present invention, FIG. 2 is a schematic diagram of an engine to which the present invention can be applied, and FIG. 3 shows a routine for calculating a correction retardation amount, a learning value, and the like. FIG. 4 is a flowchart showing a table of correction coefficients,
FIG. 5 is a flowchart showing a routine for calculating an effective ignition advance, and FIG. 6 is a diagram showing a table of basic ignition advance. 12: Knocking sensor, 16: Cylinder discrimination sensor, 18: Rotation angle sensor, 20: Control circuit, 24: Pressure sensor.

Claims (1)

(57) [Claims] 1. A knocking detecting means for detecting occurrence of knocking, and a correction delay amount for retarding ignition timing when knocking occurs and advancing ignition timing when knocking does not occur. Retardation amount calculation means; learning value calculation means for calculating a learning value for setting the corrected retardation amount to a value within a predetermined range in an operation region where knocking is most likely to occur; load detection for detecting an engine load Means, correction means for correcting the learning value so as to decrease as the engine load decreases, limiting means for limiting the correction retard amount so as to be within a limit value within the operation area, and the operation area Inside, the ignition timing is controlled by reflecting the learning value calculated by the learning value calculation means and the correction retardation amount limited by the restriction means, and the correction timing is corrected by the correction means outside the operating region. Ignition timing control apparatus for an internal combustion engine comprising an ignition timing control means for controlling the ignition timing, a is reflecting the learning value and the retard quantity correction retard amount calculated by the calculating means.