JPS6085254A - Ignition timing control method - Google Patents

Abstract

PURPOSE:To obtain the desired engine characteristics through the ignition timing control for an internal-combustion engine by igniting the engine at a spark advance angle which, during lean control, becomes larger in proportion to an air- fuel ratio and becomes smaller in inverse proportion to the rotating speed of the engine. CONSTITUTION:Under the prescribed operating conditions that the water temperature indicated by a sensor 33 is >=50 deg.C and the power is not on the increase, a control circuit 35 consisting of a micro computer maintains an air-fuel ratio at its theoretical value through the feed back control by O2 sensor 29. And, under the other prescribed operating conditions, it makes the air-fuel ratio lower than its theoretical value through the feed forward control. Under the lean control, a spark advance angle correction is obtained from the map in which the smaller the lean correction factor obtained in the fuel injection operation is, the larger the lean advance angle correction is set, while the higher the rotating speed of the engine is, the smaller it is set. In this way, with the rotating speed of the engine maintained constant, the higher the air-fuel ratio during lean operation is, the larger the spark advance angle becomes, and the desired torque can be obtained by advancing the ignition time.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application of the Invention) The present invention relates to an ignition timing control method for an internal combustion engine, and is particularly applicable to an internal combustion engine in which the air-fuel ratio is leaner than the stoichiometric air-fuel ratio under predetermined engine operating conditions. This invention relates to a preferred female ignition timing control method.

(Background of the Invention) Generally, in automobile engines that use a three-way catalyst and are equipped with exhaust gas purification measures, in order to improve exhaust emissions, the air-fuel ratio, which indicates the combustion state of the engine, is controlled to be close to the stoichiometric air-fuel ratio. There is a need to.

For example, O! detects the air-fuel ratio based on the residual oxygen concentration in the exhaust gas. Fidel pack control has conventionally been performed to bring the air-fuel ratio to the stoichiometric air-fuel ratio in accordance with the output of the engine.

When the engine is operating under light load, the amount of nitrogen oxides emitted in the exhaust gas is small, so even if the air-fuel ratio is shifted to the leaner side than the stoichiometric air-fuel ratio, the exhaust emissions do not deteriorate much and fuel efficiency can be improved. .

Based on these points, for example, feedback control is used to control the air-fuel ratio so that the engine is operated at the stoichiometric air-fuel ratio based on the air-fuel ratio signal from the 02 sensor, and the engine is operated at a leaner side than the stoichiometric air-fuel ratio. An internal combustion engine has been proposed in which the air-fuel ratio is switched between feedforward control and control depending on the operating state, thereby improving fuel efficiency.

However, the ignition timing of such an internal combustion engine is set based on the stoichiometric air-fuel ratio, and under lean control, the advance angle value may be insufficient and the desired torque and fuel efficiency may not be obtained.

(Objective of the Invention) An object of the present invention is to propose an ignition timing control method in which ignition during lean control is performed using an ignition advance value according to the air-fuel ratio.

(Structure and Effects of the Invention) The present invention is configured to ignite at an ignition advance angle that becomes smaller as the air-fuel ratio becomes larger and the engine speed becomes higher. Combustion is obtained, and it becomes possible to exhibit desired engine characteristics even under lean control.

Furthermore, since the present invention performs correction that takes into account not only the air-fuel ratio but also the engine speed, it is possible to perform ignition timing control with higher accuracy than when advance angle correction is performed based only on the air-fuel ratio.

(Example) Hereinafter, an example of the present invention will be described based on the drawings.

FIG. 1 shows an example of an internal combustion engine to which the method of the present invention is applied.

A fuel injection valve 5 is provided upstream of the throttle valve 3 in the intake pipe 1, and an intake pipe pressure sensor 7 is provided downstream of the throttle valve 3 to generate a voltage according to the intake pipe pressure.

A throttle opening sensor 9 that outputs a signal according to the throttle opening is connected to the rotating shaft of the throttle valve 3, and a throttle opening sensor 9 that outputs a signal according to the intake air temperature is connected upstream of the throttle valve 3. An intake temperature sensor 11 is attached.

Reference numeral 13 denotes a well-known conventional internal combustion engine, and the air-fuel mixture in the combustion chamber 15 is ignited by a spark plug 17 at a crank angle position (ignition advance angle) just before the end of the compression process. The high voltage boosted by the igniter 19 is supplied to the spark plug 17 via the +1 computer 21. The distributor 21 is provided with a rotation angle sensor 23 that outputs a pulse signal every 30 degrees of the crank angle, and a cylinder discrimination sensor 25 that outputs a pulse signal every 360 degrees.

The exhaust gas after combustion is discharged through an exhaust pipe 27, and an oxygen sensor (02 sensor) 29 is attached to the exhaust pipe 27, which outputs a binary signal according to the oxygen concentration in the exhaust gas. A water temperature sensor 33 that generates a voltage according to the temperature of the cooling water inside the water jacket 31 is also attached.

35 is a control circuit, as shown in FIG.
RO where the PU35a and programs described below are stored
M35b, RAM35c where numerical values etc. during calculation are stored
, backup RAM35d1 person output) 35es
35f, A/D converter 35g1 multiplexer 35h1
Output ports 35i, 35j, buffer group 35, 1 comparator 3511, waveform shaping circuit 35m, drive circuit 35n,
35p1, a pass line 35q connecting them, and a clock 35r. The intake pipe pressure sensor 7, the water temperature sensor 33, and the intake temperature sensor 11 are connected to the buffer group 35 through a single multiplexer 35h and an A/D converter 35g, and the oxygen sensor 29 is connected to the buffer group 35 through a single comparator 351. It is connected to the output boat 35f, and the cylinder discrimination circuit 25 and rotation angle sensor 23 are connected to the shaping circuit 35m.
The throttle opening sensor 19 is directly connected to the input/output boat 35f, and the fuel injection valve 5 is connected to the drive circuit 35n.
The igniter 19 is connected to output ports 35i and 35j via drive circuits 35p, respectively.

In the internal combustion engine shown in FIGS. 1 and 2, fuel is injected according to the flowchart shown in FIG.

In step P1, the engine rotation speed Ne is read based on the reference position signal S1 from the rotation angle sensor 23, and the intake pipe pressure -pm is read based on the intake pipe pressure signal S5. In step P2, the basic injection time Tp is determined based on the rotational speed Ne and the pressure pm, and in step P3, a correction calculation process is executed according to the operating conditions of the engine to determine the corrected injection time τ. Furthermore, in step P4, a final injection time τ7 is determined by making a correction according to the positive pressure of the power source. Procedure P
Determine the injection timing in step 5, and if the determination is positive, proceed to step P.
6, the injection signal S8 is output to the injection valve 5.

Here, the basic injection time Tp can be determined from the map shown in FIG. 4, and the correction calculation process is performed, for example, by the following equation.

τ = TP x FAF Under control conditions, the air-fuel ratio signal S3 from the oxygen sensor 29
If the air-fuel ratio is determined to be lean by S3, the injection amount is increased to a value such as 1.05, and if the air-fuel ratio is determined to be rich by the air-fuel ratio signal S3, the injection amount is increased. If the debt is reduced (directly, for example, 0.95), and the correction coefficient FAF is not under feedback control conditions, the correction coefficient FAF will be 1.0.

An example of the calculation procedure of the feedback correction coefficient FAF is shown in the fifth section.
As shown in the figure.

In step P11, it is determined whether a feedback condition is satisfied. For example, the conditions for feedback control are satisfied when the engine water temperature THW is 50° C. or higher, not during a starting state, but during power increase after startup, and when power is not increasing. If the conditions for feedback control are not satisfied, the feedback correction coefficient FAF is set in step P12.
is set to 1.0 so that feedback control is not executed, and this procedure ends. If the conditions are met, the process advances to step P13. In step P13, the air-fuel ratio signal S3 is read. In step P14, the voltage value represented by the air-fuel ratio signal S3 is filtered to form an air-fuel ratio lean-rich flag so that it is "1" when rich and 10 when lean. If the flag is "1", it is determined that the air-fuel ratio is too rich, and step f: is executed to make the air-fuel ratio lean.

That is, in step P16, the flag CAFL is set to zero, and the process proceeds to step P17, where it is determined whether the flag CAFR is zero.

When the flag CAFR is shifted to the over-concentration side for the first time, the flag CAFR is zero, so proceed to step P]9, subtract a predetermined value αl from the correction coefficient FAF stored in the RAM 35C, and use the result as a new correction coefficient FAF. In step P20,
3 with the flag CAFR set to 1. Therefore, if it is determined that there is excessive concentration twice or more in succession in step P15, a negative determination will always be made in step P17 passed from the second time onwards, and the step 11 [
At P18, a predetermined value β1 is calculated from the correction coefficient FAF'.
FAF
Finish the calculation.

On the other hand, if the rich flag based on the voltage value represented by the signal S3 is "0" in step P15, it is determined that the air-fuel ratio is lean, and the procedure is executed to make the air-fuel ratio rich. . That is, in step P21, the flag CAFR is set to zero, and the process proceeds to step P22, where it is determined whether the flag CAFL is zero. Flag CAF when moving to the dilute side for the first time
Since L is zero, proceed to step P23, add a predetermined value α2 to the correction coefficient FAF, and use the result as a new correction coefficient FA.
Let it be F. In step P24, the flag CA F L is set to 1. Therefore, if it is determined to be diluted twice or more consecutively in step P15, the step P22 is passed from the second time onwards.
In step P25, a predetermined value β2 is added to the correction coefficient FAF, and the result is set as a new Kosode positive coefficient FAF, and the FAF calculation is ended.

In addition, α in steps pis, β19, β23, and β25
1, α2, β1 and β2 are predetermined values.

Feedback correction coefficient F determined by this calculation means
'AF is shown in FIG. 6 together with an air-fuel ratio A/F ratio enrichment flag that is expressed by filtering the voltage value represented by the air-fuel ratio signal S3. Referring to this figure, when the air-fuel ratio switches from lean to rich or from rich to lean, the correction coefficient FAF is skipped by α1 or α2, if it remains lean, a predetermined number β1 is subtracted sequentially, and if it remains rich, the correction coefficient FAF is skipped by α1 or α2. A predetermined number β2 is added sequentially.

Next, the lean correction coefficient FLEAN will be explained.

When the lean correction coefficient FLEAN calculation routine shown in FIG. 7 is started, it is determined in step P31 whether or not the IJ-on control conditions are satisfied. For example, engine coolant? 1tTHW is 806C or more, intake pipe pressure Pm is 45
The lean control execution conditions are satisfied when the intake throttle 9 valve opening rA is 30i or less. When this condition is satisfied, the process proceeds to step P32, where a lean correction coefficient FL is determined based on the intake pipe pressure Pm from a map of intake pipe pressure Pm and lean correction coefficient FLEAN, which has the relationship shown in FIG.
EAN, this coefficient F L ); A N is stored in a predetermined storage area, and this routine ends.

On the other hand, if the lean control execution conditions are not satisfied in step P31, the lean correction coefficient FL FJ is determined in step P33.
This routine ends with AN set to 1.0.

Note that the power correction coefficient FPO is set to 1.15 when the throttle valve 3 is in a high opening range, for example, 50 degrees or more, and is set to 1.0 otherwise.

Next, the ignition timing control procedure will be explained.

When the ignition timing calculation routine shown in FIG. 9 is started, in step P41, the basic advance angle TH as shown in FIG.
Look up the basic advance angle THB from the map of B and proceed to step P42. In step F'42, the storage area FL
Based on the lean correction coefficient FLEAN stored in EAN, the lean correction coefficient F is calculated as shown in FIG.
'Determine the correction advance angle THL from the map of LEAN and lean correction advance angle Tl-LL. Then, in step P43, (
The basic advance angle THB+lean correction advance angle T)IL) is calculated to determine the final advance angle THF, and the ignition timing is determined in step P44.If the determination is affirmative, the igniter 19 is controlled by the ignition signal S9 in step P45. Then, the spark plug 17 is energized at the ignition advance angle THF.

As described above, in this embodiment, under predetermined engine operating conditions, the air-fuel ratio is maintained at the stoichiometric air-fuel ratio by feedback control,
Under predetermined engine operating conditions, the air-fuel ratio is made leaner than the stoichiometric air-fuel ratio by feedforward control, and under lean control, the lean correction progresses as the error occurs during fuel injection calculation and the smaller the correction coefficient FLEAN becomes. Angle T i (
The correction advance angle T)iL is determined from a map that is set smaller as L becomes thicker and the engine speed N11l is higher.

Therefore, if the engine speed is kept constant, the greater the air-fuel ratio during lean operation, the greater the ignition advance angle, which allows for earlier ignition timing and the desired torque.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of an internal combustion engine to which the method of the present invention is applied, FIG. 2 is a block diagram showing a detailed example of its control circuit, FIG. 3 is a flowchart showing an example of a fuel injection control procedure, and FIG. The figure shows the basic fuel injection time TPO map, Figure 5 is a flowchart showing an example of the calculation procedure of the feedback correction coefficient FAF, Figure 6 is the time chart of the beam 1-inch flag and the feedback correction coefficient F A F, and Figure 7 is the beam correction coefficient. A flowchart showing an example of FLEAN calculation procedure, FIG. 8 shows intake pipe pressure Pm and lean correction coefficients FI and E.
A graph showing the relationship between AN, Fig. 9 is a flowchart showing an example of the procedure for calculating the ignition timing, and Fig. 10 shows the basic ignition advance angle T.
The map of HB, FIG. 11 is a graph showing the relationship between the engine speed Ne and the lean correction coefficient FLEAN using the correction advance angle Tl (L as a parameter). 5...Fuel injection valve, 7...Intake pipe pressure Sensor. 13...Internal combustion engine body, 17...Spark plug. 19...Igniter, 21...Distributor. 23.25...Crank angle sensor. 35...Control circuit. Agent Unuma Tatsuyuki (and 1 other person) Figure 2 Figure 3 Figure 5 Figure 6 Figure 10 Age〉Rotation number Ne (r, p, m) Figure 11 Oy #1 rotation number Ne Procedural amendment document Patent Office Director, Patent Application (B) 2 filed on October 17, 1981, Name of the invention Ignition timing control method 3, Relationship with the case of the person making the amendment Name of the patent applicant (320) Toyota Motor Corporation 4, Agent 7. Claims column of the specification to be amended, detailed description of the invention column of the specification, and drawings. 8. Contents of the amendment (1) The scope of claims is amended as shown in the attached sheet. (2) Specification ``The higher the size, the larger it is.
The higher it is, the bigger it is.'' (4) Figure 11 has been revised as shown in the attached sheet. Claims: In controlling the ignition timing of an internal combustion engine in which the air-fuel ratio is leaner than the stoichiometric air-fuel ratio under predetermined engine operating conditions, at least in the lean air-fuel ratio state, the larger the air-fuel ratio is, the ignition advance is increased. An ignition timing control method characterized by advancing the ignition timing and increasing the ignition advance angle as the engine speed increases.

Claims (1)

[Claims] In controlling the ignition timing of an internal combustion engine in which the air-fuel ratio is leaner than the stoichiometric air-fuel ratio under predetermined engine operating conditions, the ignition advance is advanced as the air-fuel ratio increases, at least in the lean air-fuel ratio state, and An ignition timing control method characterized in that the higher the engine speed, the slower the ignition advance angle.