JPH0914115A - Ignition timing control device for internal combustion engine - Google Patents

Abstract

PURPOSE: To improve rotation stability of an engine by sensing inversion cycle of rich and lean states of an air-fuel ratio feedback correction factor, and setting an ignition timing retarding angle correction rate according to the result of determination whether a cycle is more than specified period or not. CONSTITUTION: Signals are inputted to a control unit 25 from a crank angle sensor 26, an air flow sensor 27, a water temperature sensor 27 and an oxygen sensor 29. When control is started, inversion of rich/lean states of an air-fuel ratio feedback correction factor is delayed during warming up. In the case that an inversion cycle is one second or more, an ignition timing is largely retarded. At this time, vibration due to inversion shows a frequency band causing no uncomfortable feeling. Engine stability is secured and increase of exhaust temperature is promoted even when the ignition timing is largely retarded. When warming-up is promoted and the inversion cycle is less than one second, the retarding rate of the ignition timing is decreased. The vibration of the frequency band causing uncomfortable feeling is reduced, and engine stability is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ignition timing control device for an internal combustion engine, and more particularly to retard control of ignition timing during warm-up operation after starting.

[0002]

2. Description of the Related Art As conventional ignition timing control for an internal combustion engine,
For example, there is one as shown in FIG. 7 (Japanese Patent Laid-Open No. 61-98).
970, etc.).

This is because the air-fuel ratio feedback correction coefficient α is set on the basis of the rich / lean signal of the oxygen sensor provided in the exhaust passage of the engine, and the basic fuel injection amount Tp determined from the intake air amount and the engine speed of the engine. Is corrected by the air-fuel ratio feedback correction coefficient α, and the fuel injection amount Ti = Tp
In the case where the air-fuel ratio is feedback controlled to the stoichiometric air-fuel ratio (referred to as λ control control) by calculating × α, the deviation (α-αAVE) between the air-fuel ratio feedback correction coefficient α and its average value αAVE is calculated. By correcting the ignition timing according to the deviation, that is, if the deviation is positive, the ignition timing is retarded, and if the deviation is negative, the ignition timing is advanced, the rotational stability of the engine is improved. It is intended to improve.

[0004]

However, in such a conventional ignition timing control, when the ignition timing is corrected immediately after the λ control control is started during warm-up after the engine is started, There are the following problems.

Immediately after the start of the λ control control during warm-up, the intake port and the intake valve are at a low temperature, and a large amount of fuel becomes the wall flow (including the adhering amount) of these, so that depending on the air-fuel ratio feedback correction coefficient α. When rich correction is performed by the fuel injection, the injected fuel is taken by the wall flow, and it is difficult for the actual cylinder to become rich. Further, when the lean correction is performed, it is difficult to make the inside of the cylinder lean by the inflow of the wall flow of the fuel. That is, the rich / lean inversion cycle is long immediately after the start of the λ control control during warm-up.

Therefore, if the ignition timing is retarded at the time of rich correction, the stability deteriorates until it becomes rich, but in this case, advancing the average ignition timing causes a decrease in exhaust temperature.
Further, the advance of the ignition timing during lean correction causes a decrease in exhaust temperature.

The rich / lean inversion cycle is 2-3 Hz after complete warm-up, and vibrations in this frequency band are vibrations that make humans uncomfortable. Therefore, the stability is improved by advancing / retarding the ignition timing. Immediately after the start of the λ control control during warm-up, the rich / lean inversion cycle is long, but the ignition timing cannot be retarded sufficiently.

Therefore, the rise in exhaust temperature is delayed, and the temperature rise of the catalyst for purifying exhaust gas is delayed by that amount, which may deteriorate the emission.

An object of the present invention is to solve such a problem.

[0010]

A first aspect of the present invention is an operating condition detecting means 1 for detecting an operating condition of an engine as shown in FIG.
And a basic ignition timing calculation means 2 for calculating a basic ignition timing based on the engine operating conditions, an ignition timing control means 3 for controlling an ignition timing based on the basic ignition timing, and an air-fuel ratio detected from engine exhaust. Based on the oxygen sensor 4, and based on this sensor signal, an air-fuel ratio feedback correction coefficient for the lean side is set when the air-fuel ratio is rich, and a rich side air-fuel ratio feedback correction coefficient is set for the air-fuel ratio when it is lean to perform feedback control of the air-fuel ratio supplied to the engine to the target air-fuel ratio. In the internal combustion engine including the air-fuel ratio control means 5, the reversal cycle detection means 6 for detecting the rich / lean reversal cycle of the air-fuel ratio feedback correction coefficient, and the cycle determination for judging whether the reversal cycle is a predetermined cycle or more. Means 7,
A retard correction amount setting means 8 for setting an ignition timing retard correction amount according to the determination when the engine coolant temperature is low, and an ignition timing for correcting the basic ignition timing according to the ignition timing retard correction amount. The correction means 9 is provided.

In a second aspect based on the first aspect, the temperature of the engine is a cooling water temperature.

According to a third aspect of the present invention, in the first aspect, the retard correction amount setting means, when the inversion period is a predetermined period or more,
The retard correction amount of the ignition timing is set to be larger than that when the period is less than the predetermined period.

According to a fourth aspect of the invention, in the first and third aspects, the retard correction amount setting means delays the ignition timing when the air-fuel ratio feedback correction coefficient is on the rich side when the reversal period is a predetermined period or more. The angle correction amount is corrected to decrease, and the ignition timing retard correction amount is increased to increase on the lean side.

In a fifth aspect based on the fourth aspect, the retard correction amount calculation means increases the retard correction amount of the ignition timing by a decrease correction amount according to the elapsed time after the reversal of the air-fuel ratio feedback correction coefficient. The correction amount is gradually reduced.

[0015]

When the rich / lean reversal cycle of the air-fuel ratio feedback correction coefficient is equal to or longer than the predetermined cycle, the vibration caused by the rich / lean reversal becomes a frequency band that does not cause much discomfort (the engine stability is improved. ).

According to the first aspect of the present invention, it is determined whether the rich / lean inversion cycle of the air-fuel ratio feedback correction coefficient is a predetermined cycle or longer, and when the engine temperature is low, the ignition timing retard correction amount is determined according to the determination. Is set, and the ignition timing is corrected and controlled according to the retard correction amount.

That is, when the engine temperature is low and the rich / lean reversal cycle of the air-fuel ratio feedback correction coefficient is a predetermined cycle or more, the ignition timing is greatly retarded, which causes unpleasant vibration during warm-up. No, the rise in exhaust temperature is promoted.

In the second invention, the cooling water temperature of the engine is low,
When the rich / lean inversion cycle of the air-fuel ratio feedback correction coefficient is equal to or longer than a predetermined cycle, the ignition timing is greatly retarded, whereby the rise in exhaust temperature is promoted without causing unpleasant vibration during warm-up.

In the third aspect of the invention, the ignition timing is greatly retarded during warm-up when the rich / lean inversion cycle of the air-fuel ratio feedback correction coefficient is a predetermined cycle or more, and the exhaust temperature is discharged without causing unpleasant vibration. When the rise is promoted and the rich / lean reversal cycle is shortened, that is, when the warm-up is advanced, the retard amount of the ignition timing is reduced and the rotational stability is enhanced.

According to the fourth aspect of the present invention, in contrast to the rich correction of the air-fuel ratio, the retard correction amount of the ignition timing is reduced and corrected when it is difficult to enrich the air-fuel ratio. On the other hand, by increasing the ignition timing retard correction amount when it is difficult to make the engine lean, it is possible to avoid insufficient retardation.

In the fifth aspect of the present invention, in this case, the decrease correction amount and the increase correction amount of the ignition timing retard correction amount are gradually reduced according to the elapsed time after the reversal of the air-fuel ratio feedback correction coefficient, thereby enriching. At the time of leaning, the amount of retardation is controlled.

[0022]

Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, intake air of the engine 10 is introduced from an air cleaner 11 through a throttle valve 13 provided in an intake passage 12 and an intake manifold 14. Fuel is injected from a fuel injector 15 provided in a branch of the intake manifold 14.

The air-fuel mixture in the combustion chamber is ignited by a spark plug 18 via a power transistor unit 16 and an ignition coil 17.

Exhaust gas discharged from the engine 10 is introduced into a catalyst device (three-way catalyst) 20 in an exhaust passage 19, and C
O, HC and NOx are purified and discharged.

The control unit 25 includes a crank angle sensor 2 for detecting the engine speed and crank angle.
6, an air flow sensor 27 that detects the intake air amount of the engine, a water temperature sensor 28 that detects the cooling water temperature of the engine,
A signal is input from an oxygen sensor 29 or the like that detects the oxygen concentration in the exhaust gas.

Based on these signals, the control unit 25 controls the fuel injection amount of the fuel injector 15,
Spark plug 1 via power transistor unit 16
8 ignition timing is controlled.

Next, the control contents of the control unit 25 will be described.

First, the fuel injection amount control will be described. The basic injection that determines the fuel injection amount Te of the fuel injector 15 according to the intake air amount Qa of the engine and the rotation speed Ne as shown in the following equation (1). The amount Tp (base air-fuel ratio) is multiplied by various correction coefficients Co, air-fuel ratio feedback correction coefficient α, and a learning correction coefficient for correcting a slight change in the base air-fuel ratio.

Te = Tp × α × K × Co (1) Various correction coefficients Co are the sum of the air-fuel ratio correction coefficient in the operating region, the water temperature increase correction coefficient, the start and post-start increase increase correction coefficient, and the like.
Each is read from a predetermined table based on operating conditions.

The air-fuel ratio feedback correction coefficient α is the difference between the exhaust air-fuel ratio (oxygen concentration in the exhaust gas) and the target air-fuel ratio (theoretical air-fuel ratio) during the air-fuel ratio feedback control (λ control control). Set based on. The air-fuel ratio feedback control starts while the oxygen sensor 29 is activated and the engine cooling water temperature Tw is equal to or higher than a predetermined value.

In this case, the air-fuel ratio feedback correction coefficient α is stepwise reduced by a predetermined proportional amount to the lean side when the exhaust air-fuel ratio by the signal of the oxygen sensor 29 is inverted from lean to rich with respect to the target air-fuel ratio. After that, while the rich continues, the integral is subtracted and set. Further, when the flow is reversed from rich to lean, a predetermined proportional amount is added and set stepwise to the rich side, and thereafter, an integral amount is added and set while the lean continues. The value is 1 during non-feedback control.

The injection pulse signal based on the fuel injection amount Te is output to the fuel injector 15 for control.

The ignition timing control will be described with reference to the flowchart of FIG.

In steps 1 and 2, the engine cooling water temperature Tw is read and it is determined whether or not it is below a predetermined water temperature. The predetermined water temperature is, for example, 50 ° C., and if it is below this temperature, it is determined that the ignition timing retard correction is to be performed when the water temperature is low, and the routine proceeds to step 3.

In step 3, it is judged whether or not the λ control control of the fuel injection amount is started.

When the λ control control is not started,
Proceeding to step 6, the retard correction amount ADVRTD is searched for based on the water temperature Tw from the TADVRTD1 table in which the ignition timing retard correction amount during non-λ control control is set.

When the λ control control is started, in step 4, the rich / lean inversion period TRRAM of the air-fuel ratio feedback correction coefficient α of the λ control control is read.

In step 5, the inversion period TRRAMD is 1
Determine if it is more than a second.

If the inversion cycle TRRAMD is 1 second or more,
Proceeding to step 7, the retard correction amount ADVRTD is searched based on the water temperature Tw from the TADVRTD2 table in which the ignition timing retard correction amount at this time is set.

If the inversion period TRRAMD is less than 1 second,
In step 8, the TADVRTD3 table in which the ignition timing retard correction amount at this time is set is searched for the retard correction amount ADVRTD based on the water temperature Tw.

When the cooling water temperature Tw is higher than the predetermined water temperature in step 2, the ignition timing retard correction at the low water temperature is not performed, and therefore the retard correction amount ADVRT is determined in step 9.
Set D to 0.

The retard correction amount ADVRTD is stored in the memory in step 10.

Ignition timing retard correction amount tables TA
The data of DVRTD1 to 3 is set as shown in FIG.

Table TAD under non-λ control control
The VRTD1 data is set to have the smallest retard amount. This is because before the start of λ control control,
This is because, for example, when using heavy gasoline, the air-fuel ratio may become considerably lean, and therefore it is necessary to reduce the retard amount and increase the margin for the stability limit.

After the λ control control is started, the air-fuel ratio changes around the stoichiometric air-fuel ratio, so the air-fuel ratio is less likely to be leaner than before the start, and the retard amount can be increased.

The data of the table TADVRTD2 when the inversion cycle TRRAMD is 1 second or more is the inversion cycle TRAM.
The retard amount is set to be larger than the data in the table TADVRTD3 when D is less than 1 second. When the reversal period TRRAMD is less than 1 second, that is, the reversal frequency is 2 to 3
When the frequency becomes Hz, the surge torque, which is an index showing the stability, is deteriorated and enters the frequency band where vibration is uncomfortable, so the retard amount is not so large, but the inversion period TR
When AMD is 1 second or more, the reversal frequency becomes 1 Hz or less, which is a frequency band in which vibration does not feel uncomfortable, so that the retard amount can be maximized.

These data are determined in advance based on the results of experiments conducted under each operating condition.

The basic ignition timing ADVM is read from an ignition timing map in which the ignition timing is determined based on the engine speed Ne and the basic injection amount Tp of fuel.

The stored retard correction amount ADVRTD is subtracted from the basic ignition timing ADVM (FADV = AD
VM-ADVRTD), the final ignition timing FADV is determined, and the ignition of the ignition plug 18 is executed via the power transistor unit 16.

With such a configuration, after the engine is started as shown in FIG. 4, before the λ control control is started (the period A), the retard amount of the ignition timing is set in order to maintain the stability of the engine. It has been made smaller.

When the λ control control is started, the rich / lean reversal of the air-fuel ratio feedback correction coefficient α is slow during warm-up, and when the rich / lean reversal cycle TRRAMD is 1 second or more (period B). , The ignition timing is greatly retarded.

The rich-lean inversion period TRRAMD is 1
When the time is longer than a second, the vibration caused by the reversal is in a frequency band that does not make the user feel uncomfortable, and the stability of the engine is ensured even if the ignition timing is greatly retarded. The increase in exhaust temperature is promoted by the large retard of the ignition timing.

When the warm-up progresses (before the warm-up ends) and the rich / lean reversal period TRRAM becomes less than 1 second (period C), the retard amount of the ignition timing is made smaller than the period B. .

The rich / lean inversion period TRRAMD is 1
When it is less than a second, the retard amount of the ignition timing is reduced, so that the vibration of the frequency band which is uncomfortable is reduced and the stability of the engine is enhanced. Further, the increase in exhaust temperature is promoted by the retard of the ignition timing.

In this way, the retard amount of the ignition timing can be made sufficiently large while ensuring the stability of the engine for each state of the air-fuel ratio control, so that the catalyst 20 can be activated early by the increase of the exhaust temperature. This makes it possible to significantly improve the exhaust performance.

FIG. 5 shows another embodiment of the present invention. When the rich / lean inversion period TRRAMD of the air-fuel ratio feedback correction coefficient α is 1 second or more, the retard amount of the ignition timing is adjusted according to the state of the air-fuel ratio. The correction is added to.

In this case, after the λ control control is started,
In step 7, when the rich / lean reversal cycle TRAMD of the air-fuel ratio feedback correction coefficient α is 1 second or more, the retard correction amount based on the water temperature Tw from the TADVRTD2 table of the ignition timing retard correction amount (see FIG. 3). A
While searching for DVRTD, it is determined in step 11 whether the λ control control is in rich correction or lean correction.

During rich correction, the retard correction amount ADVRTD is multiplied by 0.9 in step 12 to obtain the retard correction amount ADVRTD, which is stored in the memory in step 10.

During lean correction, the retard correction amount ADVRTD is multiplied by 1.1 in step 13 to obtain the retard correction amount ADVRTD, which is stored in the memory in step 10.

The flow of FIG. 5 is the same as that of FIG.
This is the flow in which steps 11 to 13 are added.

Λ control During warm-up after the start of control,
Since the intake port and intake valve are at low temperature and there is a large amount of fuel that causes these wall flows (including adhered components), when the rich correction is performed according to the air-fuel ratio feedback correction coefficient α, the injected fuel is the wall The air-fuel ratio in the actual cylinder becomes longer in the lean state due to the flow.

Therefore, in this case, the stability can be enhanced by reducing the retard amount of the ignition timing as shown in FIG.

When the lean correction is performed, the wall flow of the fuel flows into the cylinder, so that the actual air-fuel ratio in the cylinder becomes longer in the rich state.

Therefore, in this case, by increasing the retard amount of the ignition timing as shown in FIG. 6, the retard can be increased and the exhaust temperature can be increased without impairing the stability.

Note that the actual air-fuel ratio in the cylinder gradually becomes rich from the lean state by the rich correction, and the actual air-fuel ratio in the cylinder gradually becomes lean from the rich state by the lean correction.

Therefore, at the time of rich correction, the decrease amount of the retard amount of the ignition timing is gradually reduced (0.9 → 1.0) according to the elapsed time after the rich inversion of the air-fuel ratio feedback correction coefficient α, and At the time of lean correction, it is preferable to gradually decrease the increase amount of the retard amount of the ignition timing (1.1 → 1.0) according to the elapsed time after lean reversal of the air-fuel ratio feedback correction coefficient α.

By doing so, a more appropriate ignition timing retard can be secured.

[0069]

As described above, according to the first aspect of the present invention, when the temperature of the engine is low, the stability of the engine is ensured, the rise of exhaust temperature is promoted, and the catalyst for exhaust gas purification can be activated early. Can be activated to improve the exhaust performance.

According to the second aspect of the present invention, when the water temperature is low, the stability of the engine can be ensured, the exhaust temperature can be increased, and the catalyst for purifying exhaust gas can be activated early to improve the exhaust performance. .

According to the third aspect of the present invention, the stability of the engine can be increased and the increase in exhaust temperature can be promoted.

According to the fourth invention, the stability of the engine can be further improved.

According to the fifth aspect of the invention, it is possible to secure an appropriate ignition timing retard and further improve the stability of the engine.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment.

FIG. 2 is a flowchart showing control contents.

FIG. 3 is a data characteristic diagram of an ignition timing retard amount.

FIG. 4 is a characteristic diagram of an operating state.

FIG. 5 is a flowchart showing a main part of control contents of another embodiment.

FIG. 6 is a characteristic diagram of an operating state.

FIG. 7 is a characteristic diagram of ignition timing control of a conventional example.

FIG. 8 is a block diagram of the invention.

[Explanation of symbols]

 10 Engine 13 Throttle Valve 15 Fuel Injector 16 Power Transistor Unit 18 Spark Plug 20 Catalyst Device 25 Control Unit 26 Crank Angle Sensor 27 Air Flow Sensor 28 Water Temperature Sensor 29 Oxygen Sensor

Claims (5)

[Claims] 1. An operating condition detecting means for detecting an operating condition of the engine, a basic ignition timing calculating means for calculating a basic ignition timing based on the operating condition of the engine, and an ignition timing control based on the basic ignition timing. Ignition timing control means, an oxygen sensor that detects the air-fuel ratio from the engine exhaust, and based on this sensor signal, set the lean side air-fuel ratio feedback correction coefficient when the air-fuel ratio is rich, and set the rich side air-fuel ratio feedback correction coefficient when lean. In an internal combustion engine including an air-fuel ratio control unit that feedback-controls the supply air-fuel ratio of the engine to a target air-fuel ratio, an inversion period detection unit that detects a rich-lean inversion period of the air-fuel ratio feedback correction coefficient, and this inversion period. Cycle determining means for determining whether or not is a predetermined cycle or more, and a retard correction amount for setting an ignition timing retard correction amount according to the determination when the engine temperature is low. An ignition timing control device for an internal combustion engine, comprising: setting means; and ignition timing correction means for correcting the basic ignition timing according to the ignition timing retard correction amount. 2. The ignition timing control device for an internal combustion engine according to claim 1, wherein the temperature of the engine is a cooling water temperature. 3. The internal combustion engine according to claim 1, wherein the retard correction amount setting means sets the retard correction amount of the ignition timing larger when the reversal period is a predetermined period or more than when it is shorter than the predetermined period. Engine ignition timing control device. 4. The retard correction amount setting means, when the inversion period is equal to or longer than a predetermined period, decreases the ignition timing retard correction amount when the air-fuel ratio feedback correction coefficient is on the rich side,
The ignition timing control device for an internal combustion engine according to claim 1 or 3, wherein when the lean side is set, the retard correction amount of the ignition timing is increased. 5. The retard correction amount calculation means gradually decreases the decrease correction amount and the increase correction amount of the ignition timing retard correction amount according to the elapsed time after the reversal of the air-fuel ratio feedback correction coefficient. An ignition timing control device for an internal combustion engine as described above.