JPS63105264A - Ignition timing control device for electronic controlled fuel injection type internal combustion engine - Google Patents

Abstract

PURPOSE:To make it possible to prevent generation of torque variation, by performing ignition timing control when the desired air-fuel ratio at feedback control of air-fuel ratio is changed, according to the air-fuel ratio variation at this time. CONSTITUTION:When it is decided that present operating condition is in a thin air-fuel ratio control range, in a control unit 30, a spark advance correction value at thin air-fuel ratio control time, is referred according to real air-fuel ratio, calculated according to oxygen density in exhaust gas, which is detected by an oxygen sensor 20. After that, as air-fuel ratio becomes thinner through being advanced the control for the desired thin air-fuel ratio, the referred spark advance correction value is increased, the ignition timing is more advanced, and consequently, it is set at the engine demand ignition timing. Accordingly, if the operating condition has shifted from being under theoretical air-fuel ratio control to the thin air-fuel ratio control range, the ignition timing is not varied suddenly, and generation of torque variation at change of the desired air-fuel ratio, can be avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an ignition timing control device for an electronically controlled fuel injection type internal combustion engine, and more specifically to an electronically controlled fuel injection system in which a target air-fuel ratio is switched and set in air-fuel ratio feedback control. This paper relates to ignition timing control technology in internal combustion engines.

<Prior Art> There are the following conventional electronically controlled fuel injection internal combustion engines.

That is, the intake air flow 1 detected by the air flow meter
Basic fuel injection it'rp is determined from iQ and the engine rotational speed N detected by the crank angle sensor, ignition coil, etc.
(”-K X Q/N; K Ha constant) '!c'
Furthermore, after calculating various correction coefficients C0EF according to engine operating conditions such as engine temperature, air-fuel ratio feedbank correction coefficient α, and correction numerator s according to battery voltage, the basic fuel injection flTp is adjusted by these. Do a positive operation,
Final fuel injection amount Ti(-'rpxcOEFXα+T
s).

Then, by outputting an injection pulse signal with a pulse width corresponding to the set fuel injection lTi to the electromagnetic fuel injection valve, a predetermined amount of fuel was injected and supplied to the engine (Japanese Patent Laid-Open No. 59-203828 (Refer to the publication number, etc.)

The air-fuel ratio feedback correction coefficient α is determined based on the fuel injection amount Ti in order to control the actual air-fuel ratio determined from the oxygen concentration in the exhaust gas detected by the 02 sensor to the target air-fuel ratio (usually the stoichiometric air-fuel ratio). This is to correct the increase or decrease.

Furthermore, examples of ignition timing control in such an electronically controlled fuel injection type internal combustion engine include the following (see Japanese Patent Laid-Open No. 59-49369).

That is, the operating state of the engine, specifically the engine rotational speed N, is stored in the memory in the control unit that controls the ignition timing.
Ignition timing control values (ignition advance angle values) commensurate with and basic fuel injection amount 'rp are stored in advance, and from these stored data, a control value commensurate with engine speed N and basic fuel injection ff1Tp at that time is stored. The ignition timing control value was searched and the ignition timing was controlled from that value.

(Problems to be solved by the invention) In recent years, with the aim of improving fuel efficiency and purifying exhaust gas,
Some engines control the air-fuel ratio so that the actual air-fuel ratio is thinner than the stoichiometric air-fuel ratio when the engine is in a steady state of low-speed, low-load operation. In other words, if it is determined that the operating state is a predetermined low-speed, low-load steady-state operating state that does not require high output and allows lean burn, the actual air-fuel ratio will be approximately equal to the stoichiometric air-fuel ratio, assuming that the target air-fuel ratio is the stoichiometric air-fuel ratio in the normal state. The fuel injection amount is controlled by changing the target air-fuel ratio so that the actual air-fuel ratio becomes a predetermined lean air-fuel ratio. This aims to reduce harmful components in exhaust gas.

As shown in Figure 4, when controlling the air-fuel ratio so that it is thinner than the stoichiometric air-fuel ratio by a predetermined value,
If ignition control is not performed by advancing the ignition timing compared to the stoichiometric air-fuel ratio control, torque fluctuations may occur. For this reason, in the past, two maps were stored: an ignition timing control value map corresponding to stoichiometric air-fuel ratio control and a map corresponding to lean air-fuel ratio control, so that the conditions for performing lean air-fuel ratio control were met. In some cases, an ignition timing map for lean air-fuel ratios was used.

However, if the ignition timing map for lean air-fuel ratio control is used to immediately control ignition when the conditions for lean air-fuel ratio control are met, the actual air-fuel ratio may not reach the target lean air-fuel ratio yet. , the ignition timing will be controlled in accordance with the target lean air-fuel ratio. For this reason,
Conventionally, as shown in FIG. 5, when switching the target air-fuel ratio, that is, when switching the ignition timing map, there has been a problem in that surging occurs due to torque fluctuations due to sudden changes in the ignition timing.

The present invention has been made in view of the above problems, and when the target air-fuel ratio in air-fuel ratio feedback control is switched, ignition timing control is performed in accordance with the air-fuel ratio change at that time to prevent torque fluctuations from occurring. The purpose is to prevent

Means for Solving Problems> Therefore, in the present invention, as shown in FIG. fuel injection amount control means for feedback controlling the fuel injection amount so as to reach a predetermined target air-fuel ratio; the target air-fuel ratio is a stoichiometric air-fuel ratio and a lean air-fuel ratio thinner than the stoichiometric air-fuel ratio according to engine operating conditions; In an electronically controlled fuel injection internal combustion engine configured to switch and set the target air-fuel ratio, there is provided a basic ignition timing setting means for setting the basic ignition timing according to the engine operating state; ignition timing correction value setting means for setting a correction value of ignition timing according to the change; and ignition timing correction setting means for setting ignition timing by correcting the basic ignition timing with the correction value when switching the target air-fuel ratio. , and ignition control means for controlling ignition based on the set ignition timing.

According to this configuration, for example, when the target air-fuel ratio is set to the stoichiometric air-fuel ratio and the actual air-fuel ratio is controlled to approximately the stoichiometric air-fuel ratio, the target air-fuel ratio is switched to the predetermined lean air-fuel ratio. Sometimes, the actual air-fuel ratio gradually approaches the predetermined lean air-fuel ratio by air-fuel ratio feedback control, but the ignition timing at this time is gradually adjusted by the ignition timing correction setting means according to the change in the actual air-fuel ratio. It can be advanced. Therefore, even if the target air-fuel ratio is switched,
Ignition timing control corresponding to the target air-fuel ratio is not started immediately, but ignition control corresponding to the actual air-fuel ratio is performed, and changes in ignition timing can be made smooth.

<Example> An embodiment of the present invention will be described below based on the drawings.

FIG. 2 shows the hardware configuration of an embodiment of an electronically controlled fuel injection type internal combustion engine equipped with an ignition timing control device according to the present invention.

Engine 1 has air cleaner 2. Intake duct 3. Air is drawn in via the throttle chamber 4 and the intake manifold 5.

An air flow meter 6 is provided in the intake duct 3 and outputs a voltage signal corresponding to the intake air flow i1Q.

The throttle chamber 4 is provided with a throttle valve 7 that operates in conjunction with an accelerator pedal (not shown) to control the intake air flow! Control iQ. The throttle valve 7 has its opening degree θ
A throttle valve opening sensor 8 is attached to detect the opening of the throttle valve. The exhaust manifold 21 is provided with an oxygen sensor 20 (which detects a wide range of air-fuel ratios including the stoichiometric air-fuel ratio depending on the oxygen concentration in the exhaust gas, for example, Japanese Patent Application No. 167440/1986) as an air-fuel ratio detection means. A signal corresponding to the oxygen concentration in the exhaust gas is output to the control unit 30, and the control unit 30 determines the actual air-fuel ratio based on the input oxygen concentration.

The intake manifold 5 is provided with a fuel injection valve 9 for each cylinder, and the valve is opened by a drive pulse signal from a control unit 30 containing a microcomputer as a fuel injection amount control means, and the fuel injection valve 9 is pressurized from a fuel pump (not shown). The pressure is controlled to a predetermined pressure by a pressure regulator, and the fuel is injected into the intake manifold 5.

That is, the control unit 30 calculates the basic fuel injection fiTp (-KXQ/NiK is a constant) based on the intake air flow rate Q detected by the air flow meter 6 and the engine rotation speed N detected by the crank angle sensor 14, which will be described later. Furthermore, after calculating various correction coefficients C0EF according to engine operating conditions such as engine temperature, air-fuel ratio feedback correction coefficient α, and correction numerator s based on Panteri voltage, the basic fuel injection amount Tp is corrected and calculated using these. , final fuel injection 1tTi (”-TpXCOEFXα
+Ts). A predetermined amount of fuel is injected and supplied by outputting a drive pulse signal corresponding to the fuel injection lTi to the fuel injection valve 9.

Here, the air-fuel ratio feedback correction coefficient α is for controlling the actual air-fuel ratio detected by the oxygen sensor 20 to a predetermined target air-fuel ratio, and is for controlling the actual air-fuel ratio detected by the oxygen sensor 20 to a predetermined target air-fuel ratio. This target air-fuel ratio is set to be thinner than the stoichiometric air-fuel ratio by a predetermined value, and in other operating conditions, the target air-fuel ratio is set to the stoichiometric air-fuel ratio.

On the other hand, each cylinder of the engine l is provided with an ignition plug lO, to which the high voltage generated by the ignition coil 11 is sequentially applied via the distributor 12, thereby igniting the spark and igniting the air-fuel mixture. Ignite and burn. ignition coil 1
1, the generation timing of the high voltage is controlled via a power transistor 13 attached thereto. Therefore, the ignition timing is controlled by controlling the ON-OFF timing of the power transistor 13 using an ignition timing control signal from the control unit 30. In this way, the ignition control means in this embodiment is the ignition plug 10. Ignition coil 11. It is composed of a distributor 12 and a control full unit 3o.

A photoelectric crank angle sensor 14 is built into the distributor 12 . The photoelectric crank angle sensor 14 includes a signal disk plate 16 that rotates together with the distributor shaft 15 and a detection section 17. The signal disc plate 16 is formed with 360 slits 18 for position signals (1° signal) and 4 slits 19 for reference signals (180° signal) in the case of a 4-cylinder engine. One of the signal slits 19 is also used to identify one cylinder of fish.

The detection unit 17 detects these pickpockets 7) 18 and 19,
A reference signal including a position signal and a cylinder discrimination signal is output. Here, it is possible to calculate the engine rotation speed N by measuring the period of the reference signal. Therefore, the crank angle sensor 14 detects not only the crank angle but also the engine rotation speed N.

Next, basic ignition timing setting means 1 ignition timing correction value setting means 2
Control unit 3 that also serves as ignition timing correction setting means
The ignition timing (ignition advance) control based on 0 will be explained based on the flowchart of FIG.

In step 1 (indicated as "S" in the figure, the same applies hereinafter), the intake air flow i1Q, throttle valve opening θ1, engine rotation speed N, and exhaust gas detected by each sensor 6, 8, 14, 20 are calculated. Enter the oxygen concentration.

In step 2, the intake air flow i1 input in step 1 is
Basic fuel injection ITp based on Q and engine speed N
(-KXQ/N; K is a constant).

In step 3, data on ignition timing (ignition advance angle) is searched based on the basic fuel injection amount Tp calculated in step 2 and the engine rotational speed N input in step 1. That is, the microcomputer built into the control unit 30 has preset and stored data on ignition timing that corresponds to the basic fuel injection 1tTp and the engine rotational speed N and is appropriate for the operating state at that time. The optimum ignition timing at that time is searched from among the data.

It should be noted that the above ignition timing data is obtained by experimenting in advance to find the optimal ignition timing in a state where the actual air-fuel ratio is controlled to approximately the stoichiometric air-fuel ratio, and the actual air-fuel ratio is not controlled to the stoichiometric air-fuel ratio. Under these conditions, the ignition timing is not optimal, and the leaner the actual air-fuel ratio, the more it is necessary to advance the ignition timing (see Figure 4).

In step 4, it is determined whether the current engine operating state is a steady operating state. Specifically, for example, the previous value and current value of the opening θ of the throttle valve 7 detected by the throttle valve opening sensor 8 are compared to determine the opening change rate Δθ, and this opening change rate Δθ is determined as a predetermined value. Engine 1 when
is determined to be in a steady operating state. Note that the determination of the steady operating state may be made based on the basic fuel injection amount change rate ΔTp, the engine rotational speed change rate ΔN, etc., in addition to the throttle valve opening change rate Δθ.

When it is determined in step 4 that the engine 1 is in a steady operating state, in the next step 5, the current operating state is a state in which the target air-fuel ratio of air-fuel ratio feedback control should be set thinner than the stoichiometric air-fuel ratio by a predetermined value ( (lean air-fuel ratio control region).

Specifically, the basic fuel injection amount Tp calculated in step 2
When the engine rotational speed N input in step 1 is both below a predetermined value and is in a predetermined low-speed, low-load operating region, it is determined that the lean air-fuel ratio control ll9M region is in effect.

In step 5, is the current operating state on the lean air-fuel ratio side? 11
When it is determined that the current is in the pI range, in step 6, the advance angle correction value during lean air-fuel ratio control is set to the oxygen sensor 2.
The search is performed based on the actual air-fuel ratio determined based on the oxygen concentration in the exhaust gas detected by 0. This advance angle correction value is stored and set in advance in the microcomputer in the control unit 30 so that it becomes larger as the air-fuel ratio becomes thinner, as shown in the flowchart. This is because if the ignition timing is not advanced as the actual air-fuel ratio becomes leaner, torque fluctuations will occur as shown in FIG. 4.

When the advance angle correction value of the ignition timing is retrieved in step 6, in the next step 7, the ignition timing data retrieved in step 3 is advanced and set based on this advance angle correction value. Therefore,
Even if the current operating state is in the lean air-fuel ratio control region, if the actual air-fuel ratio is close to the stoichiometric air-fuel ratio, the advance angle correction value searched in step 6 will be small and the ignition timing set in step 7 will be set in step 3. As the control to the target lean air-fuel ratio progresses and the air-fuel ratio becomes leaner, the advance angle correction value searched in step 6 becomes larger and the ignition timing becomes more advanced. The ignition timing is set to the engine required ignition timing as shown in FIG. In other words, the ignition timing is such that the advance angle is below the permissible limit for nitrogen oxide generation and the knocking generation limit, but does not cause torque fluctuation (the ignition timing shown in the crescent-shaped blank area surrounded by diagonal lines in Fig. 4). As such, ignition control is performed according to changes in the air-fuel ratio.

Therefore, even when the state is shifted from the stoichiometric air-fuel ratio control to the lean air-fuel ratio control region, the ignition timing does not change suddenly, and torque fluctuations can be avoided when switching the target air-fuel ratio.

When the advance angle correction setting of the ignition timing is made in step 7, ignition processing is performed in step 8 based on the corrected ignition timing.

On the other hand, when it is determined in step 4 that the engine 1 is not in a steady operating state, or in step 5, the lean air-fuel ratio control 'a
If it is determined that it is not in the range, the advance angle correction in step 6.7 is skipped and the process proceeds to step 8, where ignition processing is performed based on the ignition timing data retrieved in step 3.

In this embodiment, the advance angle correction value is stored in correspondence with the air-fuel ratio, but the advance angle correction value is also stored in correspondence with the elapsed time from when the conditions for lean air-fuel ratio control are met. You may also let them do so.

That is, the change in air-fuel ratio from when the conditions for lean air-fuel ratio control are met until the actual air-fuel ratio approximates the target lean air-fuel ratio is determined in advance through experiments, and the air-fuel ratio is adjusted to correspond to the change in air-fuel ratio over this time. The advance angle correction value may be set in correspondence with the elapsed time.

In addition, until the target lean air-fuel ratio is reached, the ignition timing is set according to the actual air-fuel ratio or the elapsed time described above as shown in this example, and when the target lean air-fuel ratio is reached, the ignition timing is The ignition timing may be controlled using an ignition timing map (corresponding to the basic fuel injection amount Tp and engine rotational speed N) for lean air-fuel ratio control.

Furthermore, in this embodiment, the ignition timing control is performed in accordance with the air-fuel ratio change only when the target air-fuel ratio is switched from the stoichiometric air-fuel ratio to the lean air-fuel ratio. This is because when switching the target air-fuel ratio to an output mixture ratio richer than the air-fuel ratio or the stoichiometric air-fuel ratio, it is in an acceleration/deceleration state, so the torque fluctuations are large to begin with and are not affected by torque fluctuations caused by sudden changes in ignition timing. . Therefore, when switching the target air-fuel ratio from the lean air-fuel ratio to the stoichiometric air-fuel ratio, ignition control '4'B may be performed in the same manner as in this embodiment.

(Effects of the Invention) As explained above, according to the present invention, the ignition timing is set according to the actual air-fuel ratio change when changing the target air-fuel ratio, thereby reducing torque fluctuations when changing the target air-fuel ratio. This has the effect of preventing it from occurring.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of the configuration of the present invention, Fig. 2 is a system schematic diagram showing an embodiment of the present invention, Fig. 3 is a flowchart showing ignition timing control in the same embodiment, and Fig. 4 shows the air-fuel ratio and appropriate A graph showing the relationship with ignition timing, and FIG. 5 is a time chart for explaining conventional problems. ■... Engine 6... Air flow meter 10.
... Spark plug 11 ... Ignition coil 12 ... Distributor 14 ... Crank angle sensor
2o...Oxygen sensor 30...Control unit Patent applicant Japan Electronics Co., Ltd. Agent Patent attorney Fujio SasashimaFigure 4 tL-1f Ru -Book/Figure 5

Claims (1)

[Claims] An air-fuel ratio detection means for detecting an air-fuel ratio of an intake air-fuel mixture of an engine; and a fuel injection amount control means for feedback-controlling a fuel injection amount so that the detected actual air-fuel ratio becomes a predetermined target air-fuel ratio. , in an electronically controlled fuel injection internal combustion engine configured such that the target air-fuel ratio is switched between a stoichiometric air-fuel ratio and a lean air-fuel ratio thinner than the stoichiometric air-fuel ratio according to an engine operating state; basic ignition timing setting means for setting a basic ignition timing according to the target air-fuel ratio; ignition timing correction value setting means for setting an ignition timing correction value according to an actual air-fuel ratio change when switching the target air-fuel ratio; An electronically controlled fuel comprising: ignition timing correction setting means for setting ignition timing by correcting the basic ignition timing with the correction value at the time of switching; and ignition control means for controlling ignition based on the set ignition timing. Ignition timing control device for injection-type internal combustion engines.