JPS5937234A - Fuel injection rate controlling method - Google Patents

Abstract

PURPOSE:To suppress knocking by a method wherein the presence or absence of the generation of knocking is detected at every cylinder and the amount of fuel to be injected is increased or decreased at every cylinder in accordance with the detected result at every cylinder. CONSTITUTION:The presence or absence of the generation of knocking in the previous cycle is judged at the step 20. When its presence is judged, the total amount of the amount of fuel injected in the previous cycle mFn-1 and a predetermined correction amount Fc is employed as the amount of fuel to be injected in the present cycle mFn. The above-mentioned method enables to suppress knocking with no lowering of output as compared to the method, in which the ignition timing is retarded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection control method for an internal combustion engine, and more particularly to a fuel injection control method for increasing or decreasing the amount of fuel injected into each cylinder depending on whether or not knocking occurs in each cylinder. be.

If knocking occurs in an internal combustion engine, the piston will no longer transmit rotation smoothly to the crankshaft 1-, resulting in a decrease in engine output, abnormal vibrations in the engine, and even abnormal heating of the engine. In order to stop or prevent such knocking from occurring, conventional controls such as detecting the 6 to 10 KHz vibration caused by knocking and retarding the ignition timing have been carried out. It was done. .

However, knocking is caused not only by the ignition timing but also by the air-fuel ratio (
It is also possible to suppress the occurrence by changing the weight ratio of air and fuel (3+), and this method
In terms of drivability, the output is not only low compared to the 911J platform that controls the UJ, but the driver does not feel a sense of deceleration (a)
It turned out that it was.

The present invention has been made based on this knowledge, and its purpose is to remove the fuel 1 in the cylinder where the fugitive occurs.
11' The aim is to suppress and cover knocking by controlling the air-fuel ratio.

[1] The J3 is installed in an internal combustion engine equipped with an electronic fuel injection device, and the presence or absence of knocking is detected in each cylinder based on the combustion pressure signal of a combustion pressure sensor installed in each cylinder of the engine. This is achieved by a fuel injection control method characterized by increasing or decreasing the amount of fuel injected into each cylinder from the fuel R11l control device according to the detection result.

The present invention will be described below with reference to examples and drawings.

First, Fig. 1 shows an engine (4) of an embodiment to which the present invention is applied.
FIG. 3 is a schematic diagram showing the outline of peripheral devices in a two-cycle, four-cylinder engine (size shown) and -. In the figure, 1 is an engine, 2 is a crank angle generating disc directly connected to a crankshaft, and mesh nets are arranged at equal intervals around the outer periphery of the disc.

3 represents a crank angle detector consisting of a pickup coil that generates a crank angle signal in synchronization with the rotation of the crank angle generating disk 2. Reference numeral 4 represents a combustion pressure sensor υ which is integrated into the spark plug and detects the pressure within the cylinder, that is, the combustion pressure. 5 is an air flow meter that measures the intake air amount of the engine 1, 6 is a fuel tank, 7 is an intake manifold, 8 is a fuel injection valve installed in the intake manifold 7, and 9 is an exhaust 1 manifold. It represents.

Furthermore, 10 is a combustion L1 sensor 4 and a crank angle detector 3.
An amplifier 11 with high input impedance amplifies the detection signal of 6"□ '10K which is output when knocking occurs from the combustion pressure signal outputted through the amplifier 10.
Reference numeral 12 represents a control circuit including a bandpass filter of known dimensions for extracting a knocking signal in a frequency band of Hz, and a control circuit including a microblower.

In addition, the control circuit v812 is controlled by the input port 1 as shown in FIG.
~133, Output 1-14, To input/output data 1) RAM (random access method) 15 for temporarily storing calculation data, ROM (read only memory) 16 for storing control programs, etc., data R's fraud processing and control
It is composed of a microprocessor, that is, a CPU (central processor 1 nit) 17, which operates according to a control program in the OM 16.

To explain the operation of this embodiment configured as above, first, when the engine 1 is started, the crankshaft rotates, and the crank angle signal output from the crank angle detector 3 and the various signals from the combustion pressure sensor 4 are transmitted. The combustion pressure signals of the cylinders are sent to the amplifier 10, the amplified signals are sent to the south IB control circuit 12, and the combustion pressure signals are sent to the south IB control circuit 12 through the bandpass filter 11. Only signals in the frequency band are sent to the control circuit 12. Further, an intake air amount detection signal is sent from the air flow meter 5.

Then, in the control circuit 12, according to the control program in the ROM 16, the engine rotation speed N and the engine load Q/N are calculated from the crank angle signal and the intake air JIQ, and the presence or absence of a knocking signal is determined by 8 pI to determine the necessary value for the current engine condition. The fuel injection amount is calculated, and based on the calculation result,
Predetermined fuel is injected from the fuel injection valve 8 in synchronization with the crank angle signal and sent into the cylinder. Thereafter, similar control is repeatedly performed while the engine is starting.

And the amount of fuel injection considering the presence or absence of knocking (
Calculation of the injection amount (hereinafter also referred to as injection amount) is performed according to a control program "injection amount correction" routine as shown in the flowchart of FIG. The processing will be explained below according to this 70-day 1~.

This routine uses the basic fuel injection calculation routine for each cylinder calculated by the basic fuel injection calculation routine (not shown). )I@tnF(m=
After the cylinder numbers 1 to 4 (representing cylinder numbers 1 to 4) are determined, processing is started at a predetermined timing using a predetermined crank angle signal.

When the process of this routine is started, first, the sumitub 20 determines whether knocking occurred in J3 in the previous cycle and was light or normal.

If it is determined that no knocking occurred during the previous recycle, processing will proceed to the sumitub 21.

At a3 in the sumitub 21, it is determined whether or not knocking has occurred in the current engine. And if knocking does not occur even when the engine is running at full speed, the judgment result of Noreposujitub 21 is rNOJ, the basic injection fBmF is taken as the actual injection amount, and the processing of this routine is ended. Basic injection amount 111 in the "injection" routine (not shown)
Fuel is injected by F. The same process is repeated thereafter unless knocking occurs.

Next, if knocking occurs in any cylinder, for example, the first (#1) cylinder, the determination in step 20 is "NO" since knocking did not occur in the previous cycle, and the process proceeds to step 21.

In step 21, since knocking has occurred in the current cycle, the determination is rYEsJ and step 2
Proceed to step 2.

In step 22, the injection fiI in the previous cycle is
IIFη-1 (m=1 since knocking occurs in the #1 cylinder) plus a predetermined correction MFc is injected in the current cycle as ff1mFζ, and the water routine processing is completed. In addition, the correction ff1F in this case
c is, for example, 10 of the injection amount mF^-1 of the previous cycle.
%, and the basic injection amount is ignored, but even during acceleration, the amount of fuel increases by FC, so the acceleration response does not become dull.

When the water routine process is executed in the next cycle, the determination result in step 20 is "rYES" and the process moves to step 23.

In step 23, if knocking has occurred in the current cycle (the determination result is YES), the process moves to step 24.

In step 24, the injection amount m1:/rL and Jn1 is calculated by adding the correction amount "C" to the current cycle as in step 22, which was injected in the previous cycle. The processing of the water routine ends.

In step 24, a limit is set so that the air-fuel ratio does not fall below 8.

On the other hand, if it is determined in the switch 23 that knocking has not occurred in the current cycle, the process moves to step 25.

In step 25, since knocking has not occurred, the injection amount mF,'z in the previous cycle is supplemented with f.
fl F c is subtracted and this is the current cycle injection m F
, l, and the processing of this routine ends.

That is, if knocking continues to occur, the processes from steps 20 to 23 and 24 are repeated, and when the knocking stops occurring, the processes from -0 steps 20 to 23 and 25 are performed, and thereafter steps 20 to 23 and 25 are repeated. Processes 20 and 21 are performed and the normal process is repeated, and if this is expressed as a time chart 1-, it will be as shown in FIG. [In the same figure, the mark indicates the TDC (top dead center) of each cylinder, ↑
The mark indicates the fuel injection timing, and the mark * indicates the occurrence of knocking.In addition, in step 22.24 or 25, for example, if the injection amount of #1 cylinder is increased or decreased, the average air-fuel ratio of all cylinders 1-1 is calculated. Injection in other cylinders (#2 to #4) where knocking does not occur because the knocking is the same as before correction (4)
It is also possible to reduce or increase the number of cylinders, contrary to #1 cylinder.

By increasing the injection amount in the cylinder where the knocking is occurring, the knocking can be stopped using the control described above.

As described in detail above, the fuel injection control method of the present invention detects the combustion pressure of each cylinder, selects and detects signals indicating the occurrence of knocking included in the combustion pressure signal, and detects the occurrence of knocking. It is characterized by increasing or decreasing the amount of fuel injected depending on the situation.

Therefore, according to the present invention, when the occurrence of knocking is suppressed by increasing the amount of fuel injected into the cylinder where knocking occurs, and the ignition timing is varied, the output of the cylinder concerned is low. It becomes possible to ensure good drivability in the event of knocking without any trouble, and furthermore, it becomes possible to suppress wasteful consumption of fuel when cylinder-specific control is performed.

[Brief explanation of the drawing]

The figures are based on an embodiment in which the Kito Akikata θ is applied. Fig. 1 is a schematic diagram showing the outline of the engine and its peripheral equipment, Fig. 2 is a block diagram showing the control circuit, and Fig. 3 is a schematic diagram showing the outline of the engine and its peripheral equipment. The figure shows a flowchart showing the control program for the "injection stroke correction" routine.
-1~, Figure 4 is a time chart showing control knocking. 1... Engine (internal combustion engine) 3... Crank angle detector 4... Combustion J, lt sensor 8... Fuel Ill injection valve 11... Band pass filter 12... Control circuit 17.・・CPLJ Agent Patent Attorney Tsutomu Setatsu Figure 1b. Figure 2

Claims (1)

[Claims] In an internal combustion engine equipped with an electronic fuel injection device, the presence or absence of knocking in each cylinder is detected based on the combustion pressure signal of a combustion pressure sensor attached to each cylinder of the engine, and the detection A fuel injection control method characterized by increasing or decreasing the amount of fuel injected from the fuel injection device for each cylinder depending on the result.