JPS62294769A - Ignition timing control deice for internal combustion engine - Google Patents

Abstract

PURPOSE:To provide optimum control of ignition timing even in the event of decrease in the amount of exhaust feedback at a highland or in high temperatures by furnishing a No. ignition timing memory means in which ignition timings are stored in response to the number of engine revolutions and the degree of throttle valve opening. CONSTITUTION:A control unit 3, into which the engine number-of-revolutions signal, suction air rate-of-flow signal and throttle valve degree-of-opening signal are fed from a crank angle sensor 7, air flow meter 9 and throttle valve opening sensor 11, respectively, is equipped with a No.2 ignition timing memory means to store previously the ignition timings in response to the number of engine revolutions and the fundamental amount of fuel injection, and No.2 ignition timing memory means to store previously the ignition timing in response to the number of engine revolutions and the degree of throttle valve opening. Setting of ignition timing is made through selection of either of two ignition timings which is with smallest advance angle scanned from each ignition timing memory means and the input signal from each sensor. Thereby the optimum ignition timing is obtained which even suits for highland or in high temperatures, wherein knocking is prevented and NOX exhaustion is reduced.

Description

Detailed Description of the Invention 3. 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.

(Prior art) Conventionally, in an electronically controlled fuel injection type internal combustion engine, the basic fuel injection amount 'rp=-Q/corresponding to the intake air amount per unit rotation is calculated from the intake air vL amount Q and the engine rotational speed N. N(K
is a constant), and based on this basic fuel injection amount, fuel is injected and supplied to the engine intake system, while the ignition timing is calculated based on the engine speed N and the basic fuel injection amount 'rp (or intake pipe pressure). is controlled (Jitsukai Sho 60-1202
Publication No. 40.

(See Japanese Patent Publication No. 50-12055, etc.).

<Problems to be solved by the invention> However, such conventional electronic side i! it
In the ignition timing side '4'B device of a fuel-injected internal combustion engine, the ignition timing is always determined in accordance with the engine speed and the basic fuel injection amount, so the engine speed shown in Fig. 9 is As shown in the graphs of the characteristics of the intake air flow rate at low altitudes (solid water line) and at high altitudes (dashed line), when the density of the atmosphere decreases at high altitudes or at high temperatures, the intake air flow rate with respect to the throttle valve opening decreases. As a result, the intake pipe pressure (boost) increases with a low intake air flow rate, and even though the exhaust recirculation amount, which is affected by this, decreases or becomes zero, ignition timing control is still based on the basic fuel injection amount. By operating with the same ignition timing as when the amount of exhaust gas recirculation is large, the optimum ignition timing will be advanced too much in region A of Figure 9 at high altitudes or high temperatures, causing knocking.
Furthermore, there is a problem in that NOx in the exhaust gas also increases.

SUMMARY OF THE INVENTION In view of these conventional problems, an object of the present invention is to enable appropriate control of ignition timing even when the amount of exhaust gas recirculation decreases due to a decrease in atmospheric density at high altitudes or at high temperatures.

Means for Solving the Problems> Therefore, as shown in FIG. basic fuel injection amount calculating means for calculating a basic fuel injection amount corresponding to the intake air amount per unit rotation based on the engine speed and the engine speed; and ignition timing stored in advance in correspondence with the engine speed and the basic fuel injection amount. a first ignition timing storage means; a first ignition timing search means for searching the ignition timing from the first ignition timing storage means based on the detected engine speed and the basic fuel injection amount; The second ignition timing storage means stores the ignition timing in correspondence with the engine opening speed and the throttle valve opening, and the second ignition timing storage means stores the ignition timing in correspondence with the detected engine mouth rotation speed and the throttle valve opening. a second ignition timing search means for searching for the timing; an ignition timing selection means for selecting the one with the smallest advance angle among the two ignition timings searched by the two search means and setting the ignition timing; The ignition timing control device for an internal combustion engine is configured by providing an ignition control means for operating an ignition device at a specified ignition timing.

In the above configuration, in addition to the first ignition timing storage means that stores the ignition timing in correspondence with the engine speed and the basic fuel injection amount, the first ignition timing storage means stores the ignition timing in correspondence with the engine speed and the throttle valve opening. Equipped with a second ignition timing memory means that stores the ignition timing, it is possible to obtain the optimal ignition timing corresponding to the engine speed and throttle valve opening at high altitudes or high temperatures, preventing non-king and reducing NOx emissions. Can be reduced.

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

Referring to FIG. 2, the engine 1 is provided with spark plugs 2 for each cylinder, and these spark plugs 2 are controlled by power transistors 4, A high voltage is applied through the ignition coil 5 and the distributor 6, which ignites a spark to ignite and burn the air-fuel mixture. In addition, the spark plug 2.
The power transistor 49, ignition coil 5, and distributor 6 constitute an ignition device.

In order to control this ignition timing, reference angle and unit angle signals are sent from a photoelectric crank angle sensor 7 built into the distributor 6, an intake air flow rate signal is sent from a hot wire air flow meter 9 provided in the intake passage 8, and a throttle valve 10 is used to control the ignition timing. A throttle valve opening signal is input to the control unit 3 from a potentiometer-type throttle valve opening sensor 11 that detects the opening of the throttle valve. Incidentally, the crank angle changer 7 is used not only as a crank angle detecting means but also as an engine speed detecting means since the engine speed can be calculated from the period of the reference angle signal. Airf U-meter 9 and throttle valve opening sensor 11
Of course, these are used as the intake air flow rate detection means and the throttle valve opening detection means, respectively.

The microcomputer in the control unit 3 performs arithmetic processing according to the broach yard shown in FIG. 3 to control the ignition timing. However, this control unit 3
This not only controls the ignition timing, but also controls the fuel injection amount by the fuel injection valve 12 and the exhaust gas recirculation amount by the exhaust gas recirculation control valve 14 via the electromagnetic valve 13.

To explain the control of the ignition timing according to the flowchart in FIG. 3, in step 1 (marked as Sl in the figure, the same applies hereinafter), the engine speed N is calculated based on the period of the reference angle signal from the crank angle sensor 7. do. In step 2, the signal from the air flow meter 9 is A/D converted to read the intake air flow rate Q. In step 3, the signal from the throttle valve opening sensor 11 is A/D converted to read the throttle valve opening Th.

° Next, in step 4, the intake air flow rate Q and engine speed N
-Q/N (K is a constant) is calculated from the basic fuel injection amount Tp=corresponding to the intake air amount per unit rotation. This part 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, a fourth ignition timing memory is stored as a first ignition timing storage means.
As shown in the figure, a first map storing ignition timing (ignition advance angle) ADVTP corresponding to engine speed N and basic fuel injection amount 'rp is provided, and a second ignition timing storage means is provided. As shown in Fig. 5, the ignition timing (ignition advance angle) ADV corresponds to the engine speed N and the throttle valve opening Th.
A second map is provided which stores t+4.

In step 5, the first map is referred to and the ignition timing ADvtp is searched from the engine speed N and the basic fuel injection tTp. This portion corresponds to the first ignition timing search means.

In step 6, the second map is referred to and the ignition timing ADVt is determined from the engine speed N and the throttle valve opening Th.

Search for. This portion corresponds to the second ignition timing search means.

Next, in step 7, the engine speed N and the basic fuel injection amount Tp
Ignition timing A searched from the first map based on
Ignition timing A D searched from the second map based on D'Y TP, engine speed N, and throttle valve opening Th
If ADVrp≦ADVa8, proceed to step 8 and select the ADV with the smaller advance angle.
Set tp as the final ignition timing (ignition advance angle), and if ADV tr > ADV rH, proceed to step 9 and set ADV t with a smaller advance angle.
Set o as the final ignition timing (ignition advance angle) ADV.

These parts correspond to the ignition timing selection means.

Thereafter, 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. , these steps are repeated, and when the ignition timing reaches ADV, the process proceeds to step 12, where an ignition control signal is output to drive the power transistor 4 to perform an 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.

In addition, Fig. 7 shows the intake air fLt at a certain engine speed.
and shows the relationship between throttle valve opening and ignition timing. line m
is determined so that the relationship between the intake air flow rate (mass flow rate) and the ignition timing matches that shown in FIG. 6 at low altitudes. Line n is advanced by a predetermined value with respect to line m.

The ignition timing according to line n is determined by the stay /
7 T: ADV T1 < ADV tl
Therefore, the optimum ignition timing is the ignition timing ADV, which corresponds to the basic fuel injection amount.

At high altitudes, the intake air flow rate when the throttle valve is fully open (4/4) decreases from Qe at low altitudes to Qf, but the ignition timing changes accordingly to the basic fuel injection amount between a-b-c and d-f. The corresponding ignition timing ADV TP remains, but c −
Between d and d, the ignition timing ADVt□ corresponds to the opening degree of the throttle valve.

As the altitude further increases, the intake airflow decreases to fflQg when the throttle valve is fully open (4/4), but the ignition timing changes accordingly between a and b, the ignition timing ADV according to the basic fuel injection amount.
TP, and between b and g, the ignition timing is A according to the throttle valve opening.
Delays to DVTH.

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

In Fig. 8, at the altitude o''-s, the ignition timing is controlled to ADVtr according to the basic fuel injection amount. At the altitude S-%-t, the ignition timing is controlled to ADVTH according to the throttle valve opening, The ignition timing is retarded to compensate for the increase in the opening of the throttle valve for the same intake air flow rate depending on the altitude.At higher altitudes, the ignition timing is controlled to A D V TH according to the opening of the throttle valve. The ignition timing is 4/4 opening at the rotation speed.

In this way, at altitudes above S, the ignition timing is retarded and optimized compared to the conventional example.

In addition, in the case where the ignition characteristics are determined only by the ignition timing map according to the engine speed and the throttle valve opening without having a map of the ignition timing according to the engine speed and the basic fuel injection amount,
In order to match the required ignition timing at low altitudes, it is necessary to match line m and line n in Fig. 7, which would result in too much retardation at high altitudes, resulting in a problem of reduced output, so this method cannot be adopted. .

<Effects of the Invention> As explained above, according to the present invention, optimal ignition timing can be obtained even at high altitudes or at high temperatures, and knocking can be prevented.
Moreover, the effect of reducing the amount of NOx emissions can be obtained.

[Brief explanation of the drawing]

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 invention, Fig. 3 is a flowchart of ignition timing control, and Figs. 4 and 5 show ignition timing control. Figures 6 and 7 are diagrams showing the maps, Figure 8 is a characteristic diagram of ignition timing versus altitude, and Figure 9 is a characteristic diagram of intake air flow rate at a certain rotation speed. be. 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] Detection means for detecting the engine rotation speed, intake air flow rate, and throttle valve opening, and basic fuel for calculating the basic fuel injection amount corresponding to the intake air amount per unit rotation based on the intake air flow rate and the engine rotation speed. injection amount calculation means; first ignition timing storage means that stores ignition timing in advance in correspondence with the engine speed and basic fuel injection amount; a first ignition timing retrieval means for retrieving the ignition timing from the first ignition timing storage means; a second ignition timing storage means for storing the ignition timing in advance in correspondence with the engine speed and the throttle valve opening; a second ignition timing retrieval means for retrieving the ignition timing from the second ignition timing storage means based on the engine speed and throttle valve opening; ignition timing selection means for selecting an ignition timing with a small advance angle and setting the ignition timing;
An ignition timing control device for an internal combustion engine, comprising ignition control means for operating an ignition device at the selected ignition timing.