JPH03185237A - Fuel injection controller of internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent excessive increase of fuel injection and overheat of an exhaust system by judging whether exhaust gas is in a high temperature condition or not according to load of an internal combustion engine and an extent of delay and performing increase in fuel injection and inhibition of increase according to a judgement result. CONSTITUTION:The operating condition of an internal combustion engine M1 is detected by a means M2, and a fuel injection quantity and ignition timing of the engine M1 are calculated by a means M3 according to the above detected result. An extent of delay of the ignition timing at a means M3 is detected by a means M4 according to a knocking condition and the like detected by a means M2. Load of the internal combustion engine M1 is detected by a means M5 according the detected result of the means M2. Exhaust gas of the engine M1 is judged by a means M6 whether it is in a high temperature condition or not according to the extent of delay and the load detected by the means M4, M5, respectively. As a result, fuel injection quantity is increased when the temperature of the exhaust gas is high, and increase therein is inhibited when it is not in the high temperature condition.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel injection splitter device for an internal combustion engine having a knock control system.

[Conventional technology]

BACKGROUND ART Conventionally, there is a fuel injection amount control device that increases the fuel injection amount in a high load state to make the air-fuel ratio rich, thereby suppressing a rise in exhaust gas temperature I11.

For example, the device described in Japanese Patent Application Laid-Open No. 63-42845 determines that the internal combustion engine is under high load when the load is above a predetermined value, determines the fuel injection increase setting value in the high load state, and adjusts the setting value according to the amount of retardation of the ignition timing. The fuel injection amount is gradually increased from the initial increase value to the above-mentioned increase setting value.

(Problem to be Solved by the Invention) However, a detailed study revealed that the range in which the above-mentioned fuel injection amount must be increased is not determined solely by the load.

The operating state of an internal combustion engine with a knock control system (KO2) is determined from the relationship between the engine speed (Ne) and the intake air 1l (Q/N) corresponding to the engine load as shown in Figure 5 (
It is divided into three areas shown in A>.

In the figure, the first region (3) below the solid linework is a region in which the knock control system can maintain the exhaust gas temperature at an appropriate value by feedback control of the air-fuel ratio even if the ignition timing is at its most retarded.

A second area above the solid line ■ and below the solid line ■
When the knock control system is ignited I III 1
Among the 11 widths, the amount of retardation (AKNK) is as shown in Fig. 5 (B)! In the case of the lower side of 111II, the exhaust gas temperature can be kept at an appropriate value by feedback control, but the solid line ■
If the temperature is higher than that, OTP (overtc+tpe
(rature protect) This is an area where an increase in amount is required.

The third region (■) above the solid line (■) in Fig. 5 (A) shows that even if the ignition angle of the knock control system is at the most advanced angle, the
This is an area where an increase in TP is required.

In a conventional fuel injection amount control device, an increase set value for OTP increase is determined based on the engine rotation speed and load, and the retard amount is used only to determine this initial increase value.

Therefore, in the second region, when the amount of retardation is small, extra O
OTP required when TP is increased and the retardation amount becomes large.
There was a problem in that the exhaust gas temperature rose excessively without increasing the number of pumps, causing the exhaust system to heat up.

The present invention has been made in view of the above points, and by determining whether or not to increase the fuel injection amount based on the load and retardation angle of the internal combustion i, it is possible to avoid unnecessary increases in the fuel injection IJJm and exhaust gas. An object of the present invention is to provide a fuel injection amount control device for an internal combustion engine that prevents system overheating.

[Means to solve the problem]

FIG. 1 shows a diagram of the principle of the present invention.

In the figure, the operating state of the internal combustion engine M1 is determined by the operating state detecting means M.
2, and the calculating means M3 calculates the fuel injection amount and ignition timing of the internal combustion engine M1 according to the detection result of the operating state detecting means M2.

The retardation detection means M4 detects the retardation of the ignition timing in the reduction means M3 in accordance with the knocking state detected by the operating state detection means M2.

The load detection means M5 detects the load of the internal combustion engine according to the detection result of the operating state detection means M2.

The determining means M6 determines whether the exhaust gas of the internal combustion engine is in a high temperature state based on the load detected by the load detecting means M5 and the retarded angle detected by the retarded angle detecting means M4. Entaku instrument M
3 increases the amount of fuel injection t14m when the determining means M6 determines that the exhaust gas is in a high temperature state, and prohibits the increase in the amount of fuel injection when it is determined that the exhaust gas is not in a high temperature state.

[Effect]

In the present invention, the determining means M6 determines whether the exhaust gas is in a high temperature state using the retarded angle and the load detected by the retarded angle detecting means M4 and the load detecting means M6, respectively,
Based on this determination, execution or prohibition of increasing the fuel injection amount in the calculation means M3 is determined. Therefore, it is possible to judge whether to perform or prohibit an increase in fuel consumption more accurately than in the past, which was determined based only on the load. The injection amount is reliably increased and overheating of the exhaust system can be prevented.

〔Example〕

FIG. 2 shows a configuration diagram of an embodiment of a gasoline engine to which the 5A arrangement of the present invention is applied.

In the figure, 1 is the gasoline engine body, 2 is the piston, and 3
is a spark plug, 4 is an exhaust manifold, 5 is an intake manifold, 6 is a surge tank that absorbs the pulsation of intake air, 7 is a throttle valve that adjusts the amount of intake air, 8
is an air flow meter that measures the amount of intake air. The exhaust manifold 4 is provided with an oxygen sensor 9 that detects the residual oxygen concentration in the exhaust gas, and the intake manifold 5 is provided with a fuel injection valve 10 that injects fuel into the intake air of the gasoline engine body 1. Intake air temperature sensor 11 detects the temperature of intake air, throttle sensor 12 detects the opening degree of throttle valve 7, and knock sensor 13 is attached to cylinder block 14 to detect knocking drive.

Further, the igniter 16 generates the high voltage necessary for ignition and supplies it to the distributor 17, and the distributor 17 interlocks with the rotation of the crankshaft (not shown) and supplies the high voltage to the spark plugs of each cylinder. distributed and supplied to The rotation angle hinge +i'18 is the rotation confidence QN of 24 pulses for one revolution of the distributor 17, that is, 12 revolutions of the crankshaft.
E, and the cylinder discrimination sensor 19 outputs a rotation detection signal G of one pulse per one revolution of the distributor 17.

20 is an electronic 1iiiIJIX1 circuit, 21 is a 1-switch, and 22 is a starter motor.

The electronic fi11111 circuit 20 has a configuration shown in FIG. 3, and includes a central processing unit (CPU) 30, a read-only memory (ROM) 31 that stores a processing program, and a random access memory (RAM) used as a work area. 32 and
Backup RAM 33 retains data even after power is stopped
, an A/D converter 34 with a multi-breather function, an I10 internoace 35 with a buffer function, and a backup circuit 36 that performs backup 11JtIl, and these are interconnected by a pass line 37. .

The A/D converter 34 is supplied with the air flow rate signal from the air 70-meter 8, the intake air temperature signal from the intake air temperature sensor 11, and the knocking signal from the knock sensor 13, and digitizes each signal. , these digital signals are read by CPLI 30. Also, the I10 Interno Ace 35 has an oxygen sensor 9. Throttle sensor 1
29 Rotation angle sensor 18. Cylinder discrimination sensor 19. Signals from each key switch 21 come in, and each signal is sent to the CPU 30.
Read by

The CPU 30 calculates the ignition timing and fuel injection rJJ1 based on each sensor detection data, and uses the obtained ignition signal g
, the fuel injection signal passes through the I10 interface 35 to the igniter 16 . The fuel is supplied to each fuel injection valve 10.

Next, a control program for an embodiment of the apparatus of the present invention will be explained.

FIG. 4 shows a flowchart of an embodiment of the 0TPjl amount control process. This process is part of the fuel injection control process of the main routine, and is executed every few m5ec.

In the figure, in steps 50 and 51, it is determined whether the operating state is in the first region or the second region. At this time, the intake air ff1 (Q/N) corresponding to the engine load is determined from the air flow rate signal (Q) of the air flow meter 8 and the rotation speed (Ne) based on the rotation angle signal of the rotation angle sensor 18, and this and the rotation speed (Ne) ) to the table in FIG. 5 (A>) to determine the area.

If it is determined in step 50 that it is the first region, it is determined whether the feedback III control condition is satisfied (step 52). Here, if the feedback control conditions are not satisfied, such as when the cooling water temperature is low, at the time of starting, at the time of high load running, or at the time of fuel cut, the feedback correction coefficient FAF is forcibly set to "1" in the open control process (step 53). ”, and if the feedback control conditions are satisfied, the feedback υItll process (
In step 54>, a feedback correction coefficient FAF is calculated according to the detection signal of the oxygen sensor 9, and the process ends.

When it is determined in step 51 that the region is the second region, it is determined whether the feedback control conditions are satisfied (step 55). Here, if the feedback control conditions are not satisfied, such as when the cooling water temperature is low, when starting, when running under high load, when fuel is cut, etc., the feedback correction coefficient FAF is forcibly adjusted in the open control process (step 56), for example, 1", then it is determined whether the retardation mAKNK of the ignition timing of the knock control system is greater than or equal to the reference retardation amount AKNK1 indicated by the solid line ■ in the table shown in FIG. ), retard 1mA
If K N K is small and the exhaust gas is not in a high temperature state, the process is terminated. If the retardation amount ΔKNK is large and the exhaust gas is in a high temperature state, the rotation speed (N
e) and intake air fi (Q/N) to calculate the increase I setting value of 0TPill, which is a correction at high load.Step 5
B), the process ends. If the feedback control condition is satisfied in the step-up 55, it is determined whether the retard angle 11AKNK is greater than or equal to the reference retard angle mAKNK1 (step 59). If the retard angle 11AKNK is small and the exhaust gas is not in a high temperature state, the exhaust gas temperature can be maintained at an appropriate value by feedback I control, so the process proceeds to step 54 and after performing the feedback control W process, the process is performed. finish. Also, if the retard angle ffi:AKNK is large and the exhaust gas is in a high temperature state, it will be necessary to increase the amount of O.
After the feedback correction coefficient is forcibly set to "1j" in the oven control process in step 60, the OTP is set in step 58.
The increase set value for lifting is incremented by 11, and the process ends.

When the process shown in FIG. 4 is completed, the fuel injection time TAU is calculated in the subsequent main routine using the feedback correction coefficient FAF, the OrP increase setting value, etc.

In this way, it is determined whether the exhaust gas is in a high temperature state using the retard amount and the load, and based on this determination, when the exhaust gas is in a high temperature state, the
Ptllll is performed and OTP ant growth is prohibited when the temperature is not high. Therefore, the load alone is 0TPj! It is possible to judge whether to perform or prohibit an increase more accurately than in the past, which determined whether to perform or prohibit the increase in fuel injection amount, prevents unnecessary increases in fuel injection amount, improves fuel efficiency, and ensures that the necessary increase in fuel injection amount is achieved. This can prevent overheating of the exhaust system. Furthermore, since the feedback control range is expanded compared to the conventional system, emissions are also improved accordingly.

In the above embodiment, the load range table shown in FIG. 5 (A) and the retardation amount table shown in FIG. Retard angle IA
(AKNK) may be used as a three-dimensional table to determine whether or not to perform OTP enhancement by referring to this three-dimensional table. Also, as the retard angle, the retard angle M
Of course, the amount of retardation of the actual ignition timing produced based on AKNK may be used.

〔Effect of the invention〕

As described above, according to the fuel injection control device for an internal combustion engine of the present invention, it is possible to accurately determine whether to execute or prohibit the fuel injection amount, prevent an unnecessary increase in the fuel injection amount, improve fuel efficiency and emissions, and improve fuel efficiency and emissions. It is possible to reliably increase the amount of fuel injection IJ4I and prevent overheating of the exhaust system, which is extremely useful in practice.

[Brief explanation of drawings]

Fig. 1 is a principle diagram of the device of the present invention, Fig. 2 is a configuration diagram of an embodiment of a gasoline engine to which the device of the present invention is applied, Fig. 3 is a block diagram of an electronic control circuit, and Fig. 4 is a block diagram of the CPU. Flowchart of Processing FIG. 5 is a characteristic diagram for explaining the operation of the apparatus of the present invention. Ml... Internal combustion engine, M2... Operating state detection means, M
3...Calculating means, M4...Late angle detection means, M
5... Load detection means, M6... Control judgment means, 1.
...gasoline engine, 3...spark plug, 8...
Air 70-meter, 10...Fuel injection valve, 13...
Knock sensor, 16...Igniter, 18...Rotation angle sensor, 30...CPU, 50-60...Step. No.! Figure 2 Figure 3 Figure 20 4

Claims (1)

[Scope of Claims] In a fuel injection control device for an internal combustion engine having a knock control system that detects a knocking state of the internal combustion engine and sets the amount of retardation of ignition timing, a load detection means that detects the load of the internal combustion engine. a retard angle detection means for detecting a retard angle of the ignition timing; and a retard angle detection means for detecting a retard angle of the ignition timing; and a retard angle detection means for detecting a retard angle of the ignition timing; and a determination means for determining whether or not the exhaust gas is in a high temperature state, and increases the fuel injection amount when the determination means determines that the exhaust gas is in a high temperature state, and increases the fuel injection amount when it is determined that the exhaust gas is not in a high temperature state. A fuel injection control device for an internal combustion engine, characterized in that it prohibits