JP2007092579A - Ignition timing control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely prevent occurrence of knocking without degradation in acceleration performance, in an acceleration state of an internal combustion engine. <P>SOLUTION: The acceleration state is determined based on a rate of change ΔQ of an intake air amount Q of the internal combustion engine. When the acceleration state is detected, an initial value and a hold time T of a retard correction amount are set based on the rate of change ΔQ. After retard correction by using the initial value is continued for the hold time T, the ignition timing is gradually returned up to normal ignition timing. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ignition timing control device for an internal combustion engine, and more particularly to a technique for preventing the occurrence of knocking by retarding the ignition timing in an acceleration state of the internal combustion engine.

In Patent Documents 1 and 2, the acceleration state of the internal combustion engine is detected from the throttle opening degree or the accelerator opening degree, and when the acceleration state is detected, the ignition timing is retarded in a feed-forward manner so that knocking in the initial stage of acceleration is performed. An ignition timing control device that prevents the occurrence of this is disclosed.
JP 2000-205095 A JP 11-117844 A

  By the way, in the case of the configuration in which the acceleration determination is performed based on the throttle opening or the accelerator opening and the ignition timing is retarded as in the conventional case, the acceleration determination is made depending on how the driver operates and how the accelerator is depressed. However, it is not an engine operating condition that causes knocking, but the ignition timing is retarded to reduce engine performance, or knocking occurs without being judged as being accelerated even though it is an engine operating condition that causes knocking. It might have occurred.

  The present invention has been made in view of the above problems, and can accurately determine the acceleration state of an internal combustion engine that requires correction of the retard of the ignition timing, and can reliably prevent the occurrence of knocking without degrading the acceleration performance. An object is to provide an ignition timing control device for an internal combustion engine.

  For this reason, the ignition timing control apparatus for an internal combustion engine according to the present invention determines a state where the change rate of the intake air amount of the internal combustion engine is larger than a predetermined threshold as the acceleration state of the internal combustion engine, and the ignition timing in the acceleration state. Is configured to correct the retardation.

According to the above configuration, the change speed of the intake air amount of the internal combustion engine is detected, and when the change speed is greater than the threshold value, it is determined that the internal combustion engine is in an acceleration state in which the ignition timing is to be retarded. When the acceleration state is detected based on the change rate of the intake air amount, the ignition timing is retarded in order to avoid the occurrence of knocking due to the acceleration.
Therefore, it is possible to more accurately determine the acceleration state in which knocking may occur than in the case where the acceleration determination is performed based on changes in the accelerator and throttle opening, thereby reliably preventing the occurrence of knocking during acceleration. On the other hand, it is possible to avoid deterioration of engine performance due to unnecessary correction of the ignition timing.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a system diagram of an internal combustion engine for a vehicle according to an embodiment.
In FIG. 1, air that has passed through an air cleaner 2 is sucked into each cylinder of an internal combustion engine (gasoline engine) 1 through an intake duct 3, an intake collector 4, an intake manifold 5, and an intake valve 6.

The intake air amount of the internal combustion engine 1 is adjusted by an electric control throttle 7 interposed in the intake duct 3.
The electric throttle 7 is a mechanism that opens and closes a butterfly throttle valve 7a with a throttle motor (throttle actuator) 7b.
A fuel injection valve 9 is provided in each intake port portion of each cylinder.

The air-fuel mixture formed by the fuel (gasoline) injected from the fuel injection valve 9 is ignited and combusted by spark ignition by the spark plug 15 in the combustion chamber 10.
Each ignition plug 15 is directly attached with an ignition coil 16 incorporating a power transistor.
Note that the fuel injection valve 9 can directly inject fuel into the combustion chamber 10.

The combustion exhaust in the combustion chamber 10 is discharged to the atmosphere via an exhaust valve 11, an exhaust manifold 12, and an exhaust duct 13.
The exhaust duct 13 is provided with a catalytic converter 14 for purifying harmful components in the exhaust.
The throttle motor 8, the fuel injection valve 9, and the power transistor incorporated in the ignition coil 16 are controlled by an engine control unit (ECU) 21 incorporating a microcomputer.

Detection signals from various sensors are input to the engine control unit 21.
The various sensors include an air flow meter 22 for detecting the intake air flow rate of the internal combustion engine 1 on the upstream side of the electric control throttle 7, and an exhaust air / fuel ratio on the upstream side of the catalytic converter 14 based on the oxygen concentration in the exhaust gas. An air-fuel ratio sensor 23 that detects the rotational speed of the internal combustion engine 1, an accelerator opening sensor 25 that detects the amount of depression of the accelerator pedal (accelerator opening) operated by the driver, and the throttle valve 7a is opened. A throttle sensor 26 for detecting the degree is provided.

The engine control unit 21 controls the fuel injection amount by the fuel injection valve 9 as follows.
First, basic fuel injection for forming an air-fuel mixture with a target air-fuel ratio in the cylinder intake air amount at that time from the intake air flow rate detected by the air flow meter 22 and the engine rotational speed detected by the rotational speed sensor 24. While calculating the amount, various correction coefficients are calculated based on the coolant temperature of the internal combustion engine 1 and the air-fuel ratio feedback correction coefficient is set so that the air-fuel ratio detected by the air-fuel ratio sensor 23 approaches the target air-fuel ratio. The final fuel injection amount is set by calculating and correcting the basic fuel injection amount with these correction coefficients.

Then, an injection pulse signal having a pulse width corresponding to the final fuel injection amount is output to each fuel injection valve 9 in accordance with the stroke of each cylinder.
The engine control unit 21 calculates an ignition timing (ignition advance value) from the basic fuel injection amount (engine load) and the engine rotation speed, and the ignition coil based on the ignition timing and a predetermined energization time. The power transistor built in 16 is controlled to be turned on / off.

Further, the engine control unit 21 sets a target throttle opening according to an accelerator pedal depression amount (accelerator opening) detected by the accelerator opening sensor 25, and based on the target throttle opening. The opening degree of the electric control throttle 7 is controlled.
Further, the engine control unit 21 avoids the occurrence of knocking during acceleration operation of the engine 1 by correcting the retard of the ignition timing.

The flowchart of FIG. 2 is a routine showing the correction process of the ignition timing, and is executed every predetermined minute time (for example, 10 msec).
First, in step S11, the intake air amount Q of the engine 1 detected by the air flow meter 22 is read.
In the next step S12, the change rate ΔQ of the intake air amount Q is calculated as the difference between the current value and the previous value of the intake air amount Q read in step S11.

In step S13, it is determined whether or not the engine 1 is in an accelerated state by determining whether or not the change speed ΔQ is greater than a prestored threshold value.
If ΔQ> threshold, it is determined that the engine 1 is in an accelerated state, and the process proceeds to step S14. If ΔQ ≦ threshold, this routine is terminated.
In step S14, an initial value of the retard correction amount of the ignition timing (ignition advance value) is set based on the change speed ΔQ.

As shown in the flowchart, the initial value of the retardation correction amount is set to a larger value as the change speed ΔQ is larger, and the ignition timing is retarded more as the change speed ΔQ is larger. It has become.
In the next step S15, a holding time T for holding the ignition timing retardation correction based on the initial value is set based on the change speed ΔQ (see FIG. 3).

As shown in the flowchart, the holding time T is set to a longer time as the change speed ΔQ is larger, and the time during which the retardation correction at the initial value is continued is longer as the change speed ΔQ is larger. It is supposed to be.
In step S16, the normal ignition timing is retarded by the initial value of the retard correction amount.
In step S17, it is determined whether or not the duration of the retardation correction in step S16 has reached the holding time T.

When the duration of the retard correction has not reached the holding time T, the process returns to step S16 to continue the retard correction of the ignition timing based on the initial value.
On the other hand, if it is determined that the delay correction duration has reached the holding time T, the routine proceeds to step S18, where the retard correction amount is reduced at a constant speed (for example, 2 deg / sec), and the normal ignition timing is reached. It is made to return gradually to (refer FIG. 3).

According to the above embodiment, since it is determined whether or not the acceleration state is required to avoid knocking by correcting the retard of the ignition timing based on the change rate ΔQ of the intake air amount Q, the accelerator opening degree and the throttle opening degree are determined. The ignition timing correction for avoiding knocking can be appropriately executed as compared with the case where the acceleration determination is made based on the above.
Further, since the ignition timing correction request amount changes according to the change speed ΔQ, the initial value of the retard correction amount and the holding time T of the ignition timing correction based on the initial value are variably set according to the change speed ΔQ. By doing so, the minimum retardation correction amount and holding time T necessary for avoiding knocking can be set, and the ignition timing is retarded with an excessive amount / period, so that the operability of the engine 1 is impaired relatively easily. Can be prevented with a simple configuration.

Further, when canceling the retard correction of the ignition timing, the operation can be smoothly returned to the normal ignition timing by gradually returning to the normal ignition timing.
The holding time T may be a fixed value, and only the initial value of the retardation correction amount may be variably set according to the change speed ΔQ.
The flowchart of FIG. 4 shows a second embodiment for correcting the retard of the ignition timing during acceleration.

In the flowchart of FIG. 4, in step S21, the intake air amount Q of the engine 1 detected by the air flow meter 22 is read.
In the next step S22, the change rate ΔQ of the intake air amount Q is calculated as the difference between the current value and the previous value of the intake air amount Q read in step S21.
In step S23, it is determined whether or not the engine 1 is in an accelerated state by determining whether or not the change speed ΔQ is greater than a threshold value stored in advance.

If ΔQ> threshold, it is determined that the engine 1 is in an acceleration state, and the process proceeds to step S24. If ΔQ ≦ threshold, this routine is terminated as it is.
In step S24, a retard correction amount for the ignition timing (ignition advance value) is set based on the change speed ΔQ.
As shown in the flowchart, the retardation correction amount is set to a larger value as the change speed ΔQ is larger, and the ignition timing is retarded more as the change speed ΔQ is larger. Yes.

In step S25, the normal ignition timing is retarded based on the ignition timing retardation correction amount set in step S24.
When it is determined that the change speed ΔQ is in the acceleration state larger than the threshold value again next time, the process proceeds to step S24 again to set a retardation correction amount corresponding to the change speed ΔQ at that time.

That is, while the change speed ΔQ is greater than the threshold value, the retardation correction amount sequentially changes in conjunction with the change speed ΔQ, and when the change speed ΔQ becomes less than the threshold value, the retardation correction is performed. Cancel and return the ignition timing to the normal value (see FIG. 5).
According to the second embodiment, it is possible to accurately respond to the ignition timing retardation correction request corresponding to the change speed ΔQ, and to achieve both avoidance of knocking and the operating performance of the engine 1 at a high level.

By the way, since there is a transportation time from when the intake air passes through the air flow meter 22 until it is sucked into the cylinder, a change in the intake air amount when it passes through the air flow meter 22 is delayed in the cylinder. Will do.
On the other hand, the request for the retard correction amount of the ignition timing varies depending on the change speed of the intake air amount in the cylinder.

Therefore, in the third embodiment shown in the flowchart of FIG. 6, the ignition timing is retarded in consideration of the transport delay time.
In the flowchart of FIG. 6, in step S31, the intake air amount Q of the engine 1 detected by the air flow meter 22 is read.
In the next step S32, the change rate ΔQ of the intake air amount Q is calculated as the difference between the current value and the previous value of the intake air amount Q read in step S21.

In step S33, it is determined whether or not the engine 1 is in an accelerated state by determining whether or not the change speed ΔQ is greater than a threshold value stored in advance.
If ΔQ> threshold, it is determined that the engine 1 is in an accelerated state, and the process proceeds to step S34.
In step S34, a retard correction amount of the ignition timing (ignition advance value) is set based on the change speed ΔQ.

As shown in the flowchart, the retardation correction amount is set to a larger value as the change speed ΔQ is larger, and the ignition timing is retarded more as the change speed ΔQ is larger. Yes.
On the other hand, if ΔQ ≦ threshold, the process proceeds to step S35, and 0 is set as the retardation correction amount.

After step S34 or step S35, the process proceeds to step S36, and the delay angle correction amount data set in the latest predetermined time is updated and stored in time series.
In step S37, a delay time corresponding to the transport time of the intake air from the air flow meter 22 to the cylinder is set. The delay time is set as a fixed value or a value corresponding to the engine speed.

In the next step S38, the delay angle correction amount data at the time before the delay time is searched from the data updated in step S36.
In step S39, it is determined whether or not the retardation correction amount data retrieved in step S38 is 0. If it is 0, the routine is terminated without correcting the ignition timing.

On the other hand, when the retard angle correction amount data retrieved in step S38 is not 0 and there is a request for retard angle correction, the routine proceeds to step S40, where the normal ignition timing is based on the retrieved retard angle correction amount data. Is retarded (see FIG. 7).
According to the third embodiment, it is possible to set the retard correction amount corresponding to the change speed of the intake air amount generated in the cylinder in consideration of the transport time of the intake air, and there is the transport delay. Also, the ignition timing can be optimally retarded.

1 is a system diagram of an internal combustion engine in an embodiment. The flowchart which shows 1st Embodiment of the ignition timing correction | amendment at the time of acceleration. 3 is a time chart showing ignition timing correction characteristics in the first embodiment. The flowchart which shows 2nd Embodiment of the ignition timing correction | amendment at the time of acceleration. The time chart which shows the correction characteristic of the ignition timing in the said 2nd Embodiment. The flowchart which shows 3rd Embodiment of the ignition timing correction | amendment at the time of acceleration. The time chart which shows the correction characteristic of the ignition timing in the said 3rd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine, 2 ... Air cleaner, 3 ... Intake duct, 4 ... Intake collector, 5 ... Intake manifold, 6 ... Intake valve, 7 ... Throttle valve, 8 ... Throttle motor, 9 ... Fuel injection valve, 10 ... Combustion chamber, DESCRIPTION OF SYMBOLS 11 ... Exhaust valve, 12 ... Exhaust manifold, 13 ... Exhaust duct, 14 ... Catalytic converter, 15 ... Spark plug, 16 ... Ignition coil, 21 ... Engine control unit, 22 ... Air flow meter, 23 ... Air-fuel ratio sensor, 24 ... Rotation Speed sensor, 25 ... accelerator opening sensor, 26 ... throttle sensor

Claims (8)

An internal combustion engine ignition timing characterized in that a state in which the change rate of the intake air amount of the internal combustion engine is larger than a predetermined threshold is determined as an acceleration state of the internal combustion engine, and the ignition timing is retarded in the acceleration state. Control device. 2. The ignition timing control device for an internal combustion engine according to claim 1, wherein an ignition timing retardation correction amount is determined in accordance with a change speed of the intake air amount. 3. The ignition timing control device for an internal combustion engine according to claim 2, wherein the retard angle correction amount is increased as the change rate of the intake air amount increases. 4. The ignition timing control device for an internal combustion engine according to claim 2, wherein a predetermined delay time is set for correcting the retard of the ignition timing in accordance with the change rate of the intake air amount. 4. The internal combustion engine according to claim 2, wherein the ignition timing retardation correction amount set in accordance with the change rate of the intake air amount is set as an initial value, and the initial value is held for a predetermined holding time. Ignition timing control device. 6. The ignition timing control device for an internal combustion engine according to claim 5, wherein the holding time is variably set according to a change speed of the intake air amount. 7. The ignition timing control device for an internal combustion engine according to claim 6, wherein the holding time is set longer as the change rate of the intake air amount is larger. The ignition timing control device for an internal combustion engine according to any one of claims 5 to 7, wherein the ignition timing is gradually returned toward a normal value after the holding time has elapsed.

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