JPH0786346B2 - Ignition timing control device for internal combustion engine - Google Patents

Description

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 improvement of a technique for limiting an amount of change in ignition timing.

<Prior Art> In an electronically controlled ignition device for an internal combustion engine, generally, the engine operating region is subdivided based on the engine speed, engine load (fuel injection amount), etc. The basic ignition timing is stored in the memory of the microcomputer, and the ignition timing is controlled based on the basic ignition timing retrieved from the memory according to the engine operating condition (Japanese Patent Laid-Open No. Sho 60-96).
60-184967 gazette etc.).

<Problems to be Solved by the Invention> By the way, in order to prevent the basic ignition timing set as described above from being greatly vibrated by being influenced by the fluctuation of the engine load or the like which is a setting parameter of the ignition timing, Conventionally, a limiter value that limits the amount of change in the ignition timing for each ignition is provided, and the ignition timing is limited so as not to exceed the limiter value. That is, when the basic ignition timing obtained by searching from the map this time with respect to the previous ignition timing has a variation amount exceeding the limiter value, the ignition timing is set with the variation amount from the previous ignition timing as the limiter value. Then, the ignition control is performed based on the ignition timing in which the amount of change is limited.

However, the limiter value is based on the control temperature (for example, about 80 ° C.) of the cooling water by the thermostat,
Since it is set so that the influence of the fluctuation of the ignition timing can be avoided in the operating state below the control temperature, for example, the cooling water circulation control by the thermostat is at the inlet side of the engine water jacket, and actually the water jacket is used. In an engine in which the temperature of the cooling water therein may greatly exceed the control temperature, knocking may occur during transient operation when the temperature of the cooling water exceeds the reference temperature for setting the limiter value.

That is, for example, as shown in FIG. 4, during a transient operation in which the throttle valve is suddenly fully opened from the idle operation state,
Since the limiter value (retarder limiter value) is used as the amount of change from the ignition timing in the idle operation state, the ignition timing is gradually approached to the required ignition timing in the throttle valve fully open state for each ignition, so the limiter value is set and the desired ignition timing is set. It does not approach easily, and the state is advanced from the desired ignition timing. At this time, if the engine temperature is equal to or lower than the reference temperature for setting the limiter value, knocking will not occur when the limiter value is set, so knocking will not occur, but at a higher temperature the same If knocking occurs more easily even at the ignition timing (see FIG. 5), the limiter value limits the knocking, which causes knocking beyond the limit advance angle of knocking, possibly impairing the transient drivability. It is a thing.

The present invention has been made in view of the above problems, and provides an ignition timing control device capable of avoiding knocking during high temperature / transient operation while avoiding deterioration of drivability due to fluctuation of ignition timing at normal temperature. The purpose is to do.

<Means for Solving the Problems> Therefore, in the present invention, as shown in FIG. 1, an ignition timing setting means for setting the ignition timing based on the engine operating state,
Engine temperature detecting means for detecting the engine temperature, and limiter value setting means for variably setting a limiter value for limiting the ignition timing change amount for each ignition within a predetermined value according to the engine temperature detected by the engine temperature detecting means. When the amount of change between the ignition timing set this time by the ignition timing setting means and the previous ignition timing exceeds the limiter value set by the limiter value setting means, the change amount for the previous ignition timing is set as the limiter value this time. The ignition timing control device is configured to include the ignition timing change limiting means for newly setting the ignition timing and the ignition signal output means for outputting the ignition signal to the ignition device at the set ignition timing.

<Operation> According to the ignition timing control device, the ignition timing set by the ignition timing setting means on the basis of the engine operating state is compared with the previous ignition timing, and the variation amount of the ignition timing exceeds the predetermined limiter value. Occasionally, the ignition timing change limiting means sets a new ignition timing using the amount of change from the previous ignition timing as the limiter value. Here, the limiter value is variably set by the limiter value setting means according to the engine temperature detected by the engine temperature detecting means.

Then, the ignition signal output means outputs the ignition signal to the ignition device at the ignition timing set by the ignition timing setting means or the ignition timing newly set with the change amount limited by the ignition timing change limiting means.

That is, the permissible amount of change in the ignition timing is varied according to the engine temperature.This makes it possible to set a large limiter value in the transient operating state at high engine temperatures where knocking easily occurs. It is possible to bring the ignition timing closer to the required level quickly.

<Examples> Examples of the present invention will be described below.

Referring to FIG. 2, an air flow meter 3 for detecting an intake air flow rate Q and a throttle valve 4 are provided in an intake passage 2 of an engine 1.
And an idle switch 5 which is turned on at the fully closed position (idle position) of the above, and these detection signals are input to a control unit 6 incorporating a microcomputer. Further, the engine 1 is provided with an electromagnetic fuel injection valve 7 for each cylinder. These fuel injection valves 7 are opened / closed by a drive pulse signal output from the control unit 6 in accordance with the fuel injection amount, and fuel is injected and supplied to the engine 1.

An ignition plug 8 is provided in each cylinder of the engine 1.
The high voltage generated in the ignition coil 9 is sequentially applied to the spark plugs 8 through the distributor 10, whereby spark ignition is performed to ignite and burn the air-fuel mixture. Here, the ignition coil 9 is controlled in timing of generation of a high voltage via a power transistor 11 attached thereto. Then, the ignition timing is controlled by controlling the ON / OFF timing of the power transistor 11 by the ignition signal from the control unit 6 which also serves as the ignition signal output means. In the present embodiment, the ignition device comprises the spark plug 8, the ignition coil 9, the distributor 10, and the power transistor 11.

The distributor 10 has a built-in photoelectric crank angle sensor 12. The crank angle sensor 12 is composed of a signal disk plate 14 that rotates integrally with the distributor shaft 13, and a detection unit 15,
The signal disc plate 14 has 180 slits 16 for position signals (unit signals every 2 °) and 4 slits 17 for reference signals (reference signals for each 180) in the case of four cylinders. One of the reference signal slits 17 also serves as a cylinder discrimination signal.

The detection unit 15 detects the slits 16 and 17, and outputs a position signal and a reference signal including a cylinder discrimination signal to the control unit 6. Incidentally, the number of outputs of the position signal per unit time is counted, or
The engine speed N can be calculated by measuring the cycle of the reference signal.

Further, in the auxiliary air passage 19 that bypasses the throttle valve 4, an idle control valve 18 for controlling the amount of auxiliary air to control the engine speed N during idle operation to a target speed.
Is provided. Further, a water temperature sensor 21 as an engine temperature detecting means for detecting a cooling water temperature Tw representing the engine temperature.
Is provided so as to face the water jacket of the institution 1. In FIG. 2, 20 is an air cleaner.

Next, the ignition timing control by the control unit 6
A description will be given according to the flowchart in the figure.

In this embodiment, the control unit 6 is the third
As shown in the flowchart of the figure, the ignition timing setting means,
It also serves as ignition timing change control means, limiter value setting means, and ignition signal output means.

In step (indicated as "S" in the figure. The same applies hereinafter) 1, the engine speed N calculated based on the signal from the crank angle sensor 12 is read, and in the next step 2, the intake air detected by the air flow meter 3 is read. Read the air flow rate Q.

Then, in the next step 3, the basic fuel injection amount Tp (← K × Q / N; K corresponding to the intake air flow rate Q per unit rotation of the engine)
Is a constant). The basic fuel injection amount Tp is used to retrieve the ignition timing from the map in the next step 4, and a value calculated in another routine for fuel injection control may be read.

In step 4, the engine speed N and the basic fuel injection amount are set in advance.
From the map in which the ignition timing ADV (advance value indicating how many positions before top dead center) is stored for each of the operating states divided into a plurality of parameters using Tp as a parameter, the current engine speed N and basic Based on the fuel injection amount Tp, the ignition timing ADV in the corresponding operating state is searched and obtained.

In the next step 5, the cooling water temperature Tw detected by the water temperature sensor 21 is compared with a predetermined temperature Tw ₁ (for example, 80 ° C. which is the control temperature of the thermostat for controlling the cooling water circulation), and the current cooling water temperature Tw is determined. When the temperature exceeds the predetermined temperature Tw ₁ , the process proceeds to step 6. In step 6, ignition timing ADV
The limiter value ΔADV _MAX that limits the amount of change for each ignition is set to a predetermined value ΔADV _L. On the other hand, when it is determined in step 5 that the current cooling water temperature Tw is lower than or equal to the predetermined temperature Tw ₁ , the process proceeds to step 7, and the predetermined value ΔADV _S which is a value smaller than the predetermined value ΔADV _L is set to the limiter value ΔADV _MAX. Set as.

That is, when the cooling water temperature Tw is higher than the predetermined value temperature Tw ₁ , the limiter value ΔADV _MAX is set to be larger so that the ignition timing ADV is allowed to change more.

When the limiter value ΔADV _MAX is set in step 6 or step 7, the change amount ΔA of the ignition timing ADV is set in step 8.
Calculate DV (← | Previous ADV-Current ADV |). Here, the change amount ΔADV is the last ignition timing ADV of the previous time and the step 4 of this time.
It is the absolute value of the deviation from the ignition timing ADV obtained by searching with.

Then, in the next step 9, the limiter value ΔADV _MAX set as described above is compared with the current change amount ΔADV calculated in step 8, and the ignition timing is changed with the change amount ΔADV exceeding the limiter value ΔADV _MAX. It is determined whether ADV is newly set.

Here, when it is determined that ΔADV ≦ ΔADV _MAX , the change amount of the ignition timing ADV is a small level that does not need to be limited, so the ignition timing ADV obtained by the search in step 4 is set as the final ignition timing ADV. Continue to step 11. On the other hand, when it is determined in step 9 that ΔADV> ΔADV _MAX , it means that the ignition timing ADV has been set by changing beyond the limiter value ΔADV _MAX.
In order to limit the amount of change ΔADV to the limiter value ΔADV _MAX , go to and add the limiter value ΔADV _MAX to the previous ignition timing ADV to obtain the present ignition timing ADV.

In step 10, the ignition timing ADV is set to B as described above.
Since it is expressed by TDC, when this value changes greatly to the advance side and exceeds the limiter value ΔADV _MAX , the current ignition timing ADV is changed to the previous ADV.
+ ΔADV _MAX , change to the retard side greatly and limiter value ΔAD
When V _MAX is exceeded, this ignition timing ADV is set to the previous ADV-Δ
Set as ADV _MAX .

In this way, the ignition timing ADV is limited so as not to change beyond the limiter value ΔADV _MAX , but in the case of the present embodiment, as described above, the limiter value ΔADV _MAX is the cooling water temperature Tw at the predetermined temperature Tw. It is variably set depending on whether or not it exceeds ₁ , and the change amount ΔADV is limited by a larger limiter value ΔADV _MAX at high temperature.

Therefore, when the cooling water temperature Tw is equal to or lower than the predetermined temperature Tw ₁ , the fluctuation of the ignition timing ADV can be effectively suppressed by limiting the cooling water temperature Tw with the relatively small limiter value ΔADV _MAX . Also,
When knocking is likely to occur in a high temperature state where the cooling water temperature Tw exceeds the predetermined temperature Tw ₁ , a relatively large limiter value ΔADV _MAX is set to allow a large variation range,
It has been made possible to respond to the ignition timing ADV change request during transient operation with good responsiveness. In this way, if a large range of change is allowed at high temperatures where knocking is likely to occur, the desired ignition timing can be quickly approached during transient operation, and knocking can occur while the change is limited by the limiter value ΔADV _MAX . The occurrence can be suppressed.

When the ignition timing ADV is set in this way, step 1
Proceed to 1 to perform ignition processing. Specifically, the ON timing of the power transistor 11 (the crank angle position calculated back from the ignition timing ADV and the required energization time) is measured using the reference signal from the crank angle sensor 12 as a measurement reference, and the power transistor 11 is measured at a predetermined timing. Is turned on to start energizing the ignition coil 9, and the ignition timing ADV (power transistor 11
OFF timing), and when the ignition timing ADV is reached, the power transistor 11 is turned off to interrupt the power supply to the ignition coil 9 to generate a high voltage, and the high voltage is ignited via the distributor 10. By applying to the plug 8, spark ignition by the spark plug 8 is performed.

In the present embodiment, the detected cooling water temperature Tw and the predetermined temperature
Selects two values by comparing with Tw ₁ and the limiter value ΔADV
_{Although MAX} is variably set, a linear limiter value ΔADV _MAX is calculated according to the detected cooling water temperature Tw.
May be changed.

<Effects of the Invention> As described above, according to the present invention, the limiter value for limiting the amount of change in the ignition timing is variably set according to the engine temperature. While avoiding the deterioration of the engine performance, there is an effect that a large variation range is allowed at a high temperature where knocking is likely to occur and the desired ignition timing is rapidly controlled during transient operation to avoid knocking.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of the present invention, FIG. 2 is a system schematic diagram showing an embodiment of the present invention, FIG. 3 is a flow chart showing ignition timing control in the same embodiment, and FIG. FIG. 5 is a time chart showing a change in ignition timing for explaining the problem, and FIG. 5 is a graph showing a change in knocking caused by a change in cooling water temperature Tw. 1 ... Engine, 6 ... Control unit 8 ... Spark plug, 9 ... Ignition coil, 10 ... Distributor, 11 ... Power transistor 21 ... Water temperature sensor

Claims (1)

[Claims] 1. An ignition timing setting means for setting an ignition timing based on an engine operating condition, an engine temperature detecting means for detecting an engine temperature, and a limiter value for limiting an ignition timing change amount for each ignition within a predetermined value. A limiter value setting means for variably setting according to the engine temperature detected by the engine temperature detecting means, and a change amount between the ignition timing currently set by the ignition timing setting means and the previous ignition timing is the limiter value setting means. When the limiter value set by is exceeded, the ignition timing change limiting means for newly setting the present ignition timing by using the amount of change from the previous ignition timing as the limiter value, and the ignition signal is output to the ignition device at the set ignition timing. An ignition timing control device for an internal combustion engine, comprising: