JPH0742919B2 - Ignition timing control device for internal combustion engine - Google Patents

Description

TECHNICAL FIELD The present invention relates to an ignition timing control device in an electronically controlled fuel injection internal combustion engine.

<Prior Art> Conventionally, in an electronically controlled fuel injection internal combustion engine, a basic fuel injection amount Tp = K · Q / N (corresponding to an intake air amount per unit rotation from an intake air flow rate Q and an engine speed N). (K is a constant)
And fuel is supplied to the engine intake system based on this basic fuel injection amount, while the ignition timing is controlled based on the engine speed N and the basic fuel injection amount Tp (or intake pipe pressure). (Japanese Utility Model Publication No. 60-120240, Japanese Patent Publication No. 50-12)
055, etc.).

<Problems to be Solved by the Invention> However, in such a conventional ignition timing control device for an electronically controlled fuel injection type internal combustion engine, the ignition timing always corresponds to the engine speed and the basic fuel injection amount. As shown in Fig. 9 for the characteristics of intake air flow rate at engine speed in the case of lowlands (shown by solid lines) and in the case of highlands (shown by broken lines), the characteristics of the atmosphere When the density decreases, the intake air flow rate with respect to the throttle valve opening decreases, and as a result, the intake pipe pressure (boost) increases at a low intake air flow rate, and the exhaust gas recirculation amount depending on this increases or decreases to zero. For the ignition timing control, the optimum ignition timing is controlled in the region A of FIG. 9 at high altitude or high temperature by operating at the same ignition timing as when the exhaust gas recirculation amount is large based on the basic fuel injection amount. The engine will be advanced too far, knocking will occur, and the NO
There was a problem that x also increased.

In view of such conventional problems, an object of the present invention is to make it possible to appropriately control the ignition timing even when the exhaust gas recirculation amount decreases due to a decrease in atmospheric density at high altitude or at high temperature.

<Means for Solving Problems> Therefore, according to the present invention, as shown in FIG. 1, the detection means for respectively detecting the engine speed, the intake air flow rate, and the throttle valve opening, the intake air flow rate, and the engine. Basic fuel injection amount calculation means for calculating a basic fuel injection amount corresponding to the intake air amount per unit rotation based on the rotational speed, and ignition timing stored in advance corresponding to the engine rotational speed and the basic fuel injection amount. First ignition timing storage means, first ignition timing search means for searching the ignition timing from the first ignition timing storage means based on the detected engine speed and basic fuel injection amount, and engine speed in advance And a second ignition timing storage means that stores the ignition timing corresponding to the throttle valve opening, and an ignition timing from the second ignition timing storage means based on the detected engine speed and the throttle valve opening. A second ignition timing search means for searching and two detections An ignition timing selecting means for selecting an ignition timing having a small advance angle from the two ignition timings searched by the searching means and setting the ignition timing, and an ignition control means for operating the ignition device at the selected ignition timing. It is provided to configure an ignition timing control device for an internal combustion engine.

<Operation> In the above configuration, in addition to the first ignition timing storage means that stores the ignition timing corresponding to the engine speed and the basic fuel injection amount, it corresponds to the engine speed and the throttle valve opening. The second ignition timing storage means for storing the ignition timing is provided, and at the high altitude or high temperature, the optimum ignition timing corresponding to the engine speed and the throttle valve opening is obtained, knocking is prevented, and NOx emission amount is reduced. It can be reduced.

<Example> An example of the present invention will be described below.

Referring to FIG. 2, the engine 1 is provided with spark plugs 2 for each cylinder. These spark plugs 2 are supplied with a power transistor 4 and an ignition by a spark control signal from a control unit 3 with a built-in microcomputer. A high voltage is applied via the coil 5 and the distributor 6, whereby spark ignition is performed to ignite and burn the air-fuel mixture. The ignition plug 2, the power transistor 4, the ignition coil 5 and the distributor 6 constitute an ignition device.

In order to control the ignition timing, reference angle and unit angle signals from the photoelectric crank angle sensor 7 built in the distributor 6, intake air flow rate signal from the hot wire air flow meter 9 provided in the intake passage 8, throttle valve 10 A throttle valve opening signal from a potentiometer-type throttle valve opening sensor 11 that detects the opening of the control valve 3 is input to the control unit 3.
The crank angle sensor 7 is used not only as a crank angle detecting means but also as an engine speed detecting means because the engine speed can be calculated from the cycle of the reference angle signal. It goes without saying that the air flow meter 9 and the throttle valve opening sensor 11 are used as the intake air flow rate detecting means and the throttle valve opening detecting means, respectively.

The microcomputer in the control unit 3 carries out arithmetic processing according to the flowchart of FIG. 3 to control the ignition timing. However, this control unit 3
Is not only for controlling the ignition timing but also for controlling the fuel injection amount by the fuel injection valve 12 and the exhaust gas recirculation control valve 14 through the solenoid valve 13.
The exhaust gas recirculation amount is also controlled by.

The ignition timing control will be described with reference to the flow chart of FIG. 3. In step 1 (denoted as S1 in the figure. The same applies hereinafter), the engine speed N is calculated based on the cycle of the reference angle signal from the crank angle sensor 7. To do. In step 2, the signal from the air flow meter 9 is A / D converted and the intake air flow rate Q is read. In step 3, the throttle valve opening sensor 11
The signal from is converted into A / D and the throttle valve opening Th is read.

Next, in step 4, from the intake air flow rate Q and the engine speed N, the basic fuel injection amount corresponding to the intake air amount per unit rotation
Calculate Tp = K · Q / N (K is a constant). This portion corresponds to the basic fuel injection amount calculation means. However, this basic fuel injection amount Tp is calculated for controlling the fuel injection amount of the fuel injection valve 12, and is used for controlling the ignition timing.

On the other hand, in the ROM of the microcomputer in the control unit 3, as the first ignition timing storage means, as shown in FIG. 4, the ignition timing (ignition advance) is associated with the engine speed N and the basic fuel injection amount Tp. Angle) ADV _TP is stored in the first map, and as the second ignition timing storage means, as shown in FIG. 5, the engine speed N and the throttle valve opening Th are set.
Corresponding to and, ignition timing (ignition advance) ADV _TH is stored in a second map.

In step 5, referring to the first map, the ignition timing ADV _TP is searched from the engine speed N and the basic fuel injection amount Tp. This portion corresponds to the first ignition timing search means.

In step 6, the ignition timing ADV _TH is searched from the engine speed N and the throttle valve opening Th with reference to the second map. This portion corresponds to the second ignition timing search means.

Next, at step 7, the ignition timing ADV _TP retrieved from the first map based on the engine speed N and the basic fuel injection amount Tp.
Is compared with the ignition timing ADV _TH retrieved from the second map based on the engine speed N and the throttle valve opening Th, and ADV _TP ≤
In case of ADV _TH , proceed to step 8 and ADV with small advance angle
_TP is set as the final ignition timing (ignition advance) ADV, and A
If DV _TP > ADV _TH , proceed to step 9 and set ADV _TH with a small advance angle as the final ignition timing (ignition advance angle) ADV. These parts correspond to the ignition timing selection means.

After that, in step 10, the current crank angle CA is read based on the unit angle signal from the crank angle sensor 7, and in the next step 11, it is determined whether or not the crank angle CA matches the set ignition timing ADV. , Repeat these, ignition timing
When it becomes ADV, the process proceeds to step 12, and the ignition control signal is output to drive the power transistor 4 to perform the ignition operation.

By the way, FIG. 6 shows the relationship between the intake air flow rate, the basic fuel injection amount, and the ignition timing at a certain engine speed. This relationship is constant with respect to the intake air flow rate (mass flow rate) regardless of changes in air density due to altitude or the like.

Further, FIG. 7 shows the relationship between the intake air flow rate and the throttle valve opening and the ignition timing at a certain engine speed. The line m is determined so that the relationship between the intake air flow rate (mass flow rate) and the ignition timing in the lowland is the same as in FIG. Line n is line m
Is advanced by a predetermined value.

Since the ignition timing indicated by the line n is ADV _TP <ADV _{TH in} step 7 of FIG. 3 in the lowland, the optimum ignition timing is the ignition timing ADV _TP according to the basic fuel injection amount.

In highlands, the intake air flow rate when the throttle valve is fully opened (4/4) is Q in lowlands.
Although it decreases from e to Qf, the ignition timing is a to
The ignition timing ADV _TP according to the basic fuel injection amount remains between b to c and between d and f, but the ignition timing ADV _TH according to the throttle opening is between c and d.

When the altitude is further increased, the intake air flow rate Qg when the throttle valve is fully opened (4/4) is decreased, but the ignition timing is accordingly a to b.
During the period, the ignition timing ADV _TP according to the basic fuel injection amount, b
Between ~ g, the ignition timing is retarded to ADV _TH according to the throttle valve opening.

FIG. 8 shows the above relationship at a representative point where the engine speed and the intake air flow rate are constant, and shows the relationship between altitude and ignition timing.

In FIG. 8, at the altitudes o to s, the ignition timing ADV _TP is controlled according to the basic fuel injection amount. At the altitudes s to t, the ignition timing ADV _TH is controlled according to the throttle valve opening degree, and is retarded so as to compensate for the increase of the throttle valve opening degree for the same intake air flow rate according to the altitude. At the altitude t or higher, the ignition timing ADV _TH is controlled according to the throttle valve opening, and the ignition timing is 4/4 opening at the rotational speed.

In this way, the ignition timing is retarded and optimized as compared with the conventional example at altitudes s and above.

When the ignition characteristic is determined only by the map of the ignition timing according to the engine speed and the throttle valve opening without having the map of the ignition timing according to the engine speed and the basic fuel injection amount,
Since it is necessary to match the line m and the line n in FIG. 7 in order to match the required ignition timing in the lowlands, the retardation becomes too retarded in the highlands, which causes a problem of output reduction, and therefore cannot be adopted. .

<Effects of the Invention> As described above, according to the present invention, optimal ignition timing can be obtained even at high altitude or at high temperature, knocking can be prevented,
In addition, it is possible to reduce NOx emissions.

[Brief description of drawings]

FIG. 1 is a functional block diagram showing the configuration of the present invention, FIG. 2 is a system diagram showing an embodiment of the present invention, FIG. 3 is a flowchart of ignition timing control, and FIGS. 4 and 5 show ignition timing. FIGS. 6 and 7 are characteristic diagrams at a certain rotation speed, FIG. 8 is a characteristic diagram of ignition timing with respect to altitude, and FIG. 9 is a characteristic chart with respect to the intake air flow rate at a certain rotation speed. 1 ... Engine, 2 ... Spark plug, 3 ... Control unit, 4 ... Power transistor, 5 ... Ignition coil, 6
...... Distributor, 7 …… Crank angle sensor, 9
...... Air flow meter, 11 ...... Throttle valve opening sensor

Claims (1)

[Claims] 1. A detection means for respectively detecting an engine speed, an intake air flow rate and a throttle valve opening, and a basic fuel injection quantity corresponding to an intake air quantity per unit rotation based on the intake air flow rate and the engine speed. A basic fuel injection amount calculation means for calculating
First ignition timing storage means that stores an ignition timing corresponding to the engine speed and the basic fuel injection amount in advance, and first ignition timing storage means based on the detected engine speed and the basic fuel injection amount. A first ignition timing search means for further searching the ignition timing, a second ignition timing storage means for storing the ignition timing corresponding to the engine speed and the throttle valve opening in advance, and the detected engine speed. Second ignition timing retrieval means for retrieving the ignition timing from the second ignition timing storage means based on the throttle valve opening,
Ignition timing selection means for selecting an ignition timing with a small advance angle from the two ignition timings retrieved by the two retrieval means, and ignition control means for operating the ignition device at the selected ignition timing. An ignition timing control device for an internal combustion engine, comprising: