JPS61190146A - Fuel injection controller of internal-combustion engine - Google Patents

Abstract

PURPOSE:To improve the coefficient of purifying exhaust by correcting errors by ineffective injection time even in an extremely low fuel flow region in which fuel injection quantity of a fuel injection valve does not correspond to valve opening time and controlling properly fuel supply amount. CONSTITUTION:On the basis of the respective detecting signals of an oxygen sensor 5, intake temperature sensor 8, water temperature sensor 9, throttle position sensor 11, air flow meter 14, rotational frequency sensor 18 and cylinder judging sensor 19, an electronic control circuit 20 controls the valve opening time of a fuel injection valve 6 and the ignition timing of an ignitor 16 according to the running condition. Then, the ineffective injection time of the fuel injection valve 6 is set not only according to battery voltage but also the fuel injection time. Thus, the fuel injection quantity can be controlled to an optimum value corresponding to the running condition even in an extremely low fuel flow region. Hence the coefficient of purifying exhaust is improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a fuel injection control device for an internal combustion engine, and in particular, not only the fuel injection time required depending on the operating condition of the internal combustion engine, but also the ineffective injection of the fuel injection valve. The present invention relates to a fuel injection control device for an internal combustion engine that controls driving of a fuel injection valve while also taking time into account.

[Prior Art] Conventionally, fuel injection control devices for internal combustion engines detect various operating states of the internal combustion engine, such as intake air amount, IWA rotation speed, cooling water temperature, and intake air temperature, and detect the detected operating states. Based on this, the fuel injection time of the fuel injection valve is calculated and the fuel injection valve is driven and controlled. In addition, since the fuel injection valve has a delay time (invalid injection time) from when it receives a drive signal until it actually injects fuel, this should be taken into consideration when determining the fuel injection time determined according to the operating conditions above. It is also practiced to drive the fuel injection valve using the time added to this invalid injection time.

[Problems to be Solved by the Invention] However, the above-mentioned invalid injection time is
As described in No. 537, although correction for the battery voltage has been considered, no consideration has been given to the flow rate characteristics of the fuel injection valve itself, and the correction for the fuel injection time, that is, the injection amount. was assumed to be a constant value. In other words, when the battery voltage drops, such as during startup, the ineffective injection time is increased, and control is performed so that fuel can be supplied to the internal combustion engine with the fuel injection time (amount) determined according to the operating condition. As shown in Figure 2, due to the magnetic characteristics of the magnetic device that opens the fuel injection valve, the injection amount changes greatly with respect to the opening time of the fuel injection valve on the extremely low fuel flow side. No consideration was given to the characteristics.

Therefore, during light load operation such as in a deceleration region where fuel cut control is not executed, the amount of fuel supplied to the engine deviates significantly from the target amount, the air-fuel ratio deviates from the target value, and the three-way catalyst is not effectively utilized. There is a problem of deterioration of exhaust components (HC, Co, NOX).Figure 2 shows the error in the opening time of the fuel injection valve and the fuel injection amount from the designed values when the battery voltage is constant. .

The present invention maintains the air-fuel ratio at a target value, improves the purification rate of exhaust gas, and improves the purification rate of exhaust gas by setting the invalid injection time in consideration of the flow rate characteristics of the fuel injection valve as shown in FIG. The purpose of this invention is to provide a fuel injection control device for an internal combustion engine that prevents deterioration, and has the following configuration.

[Means for Solving the Problems] That is, the configuration of the present invention as a means for solving the above problems, as shown in FIG.
2, a fuel injection time calculation means M3 that calculates the fuel injection time based on the detected operating state of the internal combustion engine M1, and using the calculated fuel injection time as one parameter,
an invalid injection time calculation means M5 that calculates an invalid injection time of the fuel injection valve M4; and a fuel injection unit that outputs a drive signal to the fuel injection valve M4 for a time obtained by adding the calculated invalid injection time and the fuel injection time. The gist of the present invention is a fuel injection control device for an internal combustion engine, which is characterized by comprising a valve drive means M6.

Here, the operating state detection means M2 is for detecting the operating state of the internal combustion engine, and is an air flow meter that detects the amount of intake air, a rotation speed sensor that detects the engine speed, or an intake pipe. Intake pressure sensors that detect the internal combustion engine's load, such as intake pressure sensors that detect pressure, water mtz sensors that detect cooling water temperature, intake air temperature sensors that detect intake air temperature, starting sensors that detect when the internal combustion engine is started, and exhaust gas sensors. Oxygen! Various sensors conventionally used in fuel injection control devices can be mentioned, such as an oxygen sensor that detects oxidation.

Further, the fuel injection time calculating means M3 calculates the fuel injection time based on the operating state of the internal combustion engine detected by the operating state detecting means M2. The basic fuel injection time is determined from the number or intake pipe pressure, and the injection time is corrected based on the cooling water temperature, intake air temperature, etc., and the fuel injection time is calculated.

Next, the invalid injection time calculation means M5 is a main part of the present invention, and whereas in the past the invalid injection time was simply set to a constant value or was set based on the battery voltage, in the present invention, the invalid injection time When setting the time, the fuel injection time calculated by the fuel injection time calculation means M3 is set to 1.
The ineffective injection time is determined by using the two parameters as two parameters.

Then, the fuel injection valve drive means M6 outputs a drive signal to the fuel injection valve M4 in the time obtained by adding the invalid injection time and the fuel injection time determined as above, and outputs a drive signal to the fuel injection valve M4.
Drive 4.

The fuel injection time calculation means M3, the invalid injection time calculation means M5, and the fuel injection valve drive means M6 are normally executed as one process of a microcomputer for internal combustion engine opening control.

[Operation] In the fuel injection control device of the present invention having such a configuration, the invalid injection time is calculated using the fuel injection amount determined based on the operating state of the internal combustion engine as one parameter, and the fuel injection valve is drive-controlled. Ru.

Therefore, as shown in FIG. 2, even in the extremely low flow rate range of fuel where the fuel injection amount of the fuel injection valve does not correspond to the valve opening time, the error can be corrected by using the invalid injection time. It becomes possible to optimally control the fuel gate to be supplied.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

First, FIG. 3 is a schematic system diagram showing a four-stroke, four-cylinder internal combustion engine and its peripheral devices in an embodiment to which the present control device is applied.

1 is an engine, 2 is a piston, 3 is a spark plug, 4 is an exhaust manifold, 5 is provided in the exhaust manifold 4,
An oxygen sensor detects the residual oxygen concentration in exhaust gas; 6 is a fuel injection valve provided for each cylinder and injects fuel; 7 is an intake manifold; 8 is provided in the intake manifold 7 and sent to the engine body 1 An intake air temperature sensor that detects the temperature of intake air, 9 a water temperature sensor that detects the cooling water temperature of the engine 1, 10 a throttle valve, 11 that is linked to the throttle valve 10 and outputs a signal according to the opening degree of the throttle valve 10. 12 is a bypass passage that is an air passage that bypasses the throttle valve 10; 13 is an idle speed control valve (ISCV) that controls the opening area of the bypass passage 12 to control the idle rotation speed; 14 is an intake air An air flow meter 15 measures the amount of air, and an air cleaner 15 purifies the intake air.

Further, 16 is an igniter that is equipped with an ignition coil and outputs the high voltage necessary for ignition, and 17 is a distributor that is linked to a crankshaft (not shown) and distributes the high voltage generated by the igniter 16 to the spark plugs 3 of each cylinder. , 18
is installed in the distributor 17 and rotates 24 times per revolution of the distributor 17, that is, two revolutions of the crankshaft.
19 is a cylinder discrimination sensor that outputs one pulse signal per revolution of the distributor 17; 20 is a cylinder discrimination sensor that receives signals from each of the above-mentioned sensors; 6 and igniter 16
The electronic control circuits that output drive signals to the circuits and the like are respectively shown.

Next, FIG. 4 is a block diagram of the electronic &11111 circuit 20.

In the figure, reference numeral 21 denotes a central processing unit (CP) that inputs and calculates data output from each sensor according to a control program, and performs processing to control the operation of various devices such as the fuel injection valve 6 and igniter 16.
LI), 22 is a read-only memory (ROM) in which data such as the control program and a map for calculating the ignition advance angle are stored, and 23 is a read-only memory (ROM) in which data input to the electronic control circuit 20 and data necessary for calculation control are stored. A random access memory (RAM) 24 that is temporarily read and written is a backup random access memory (RAM) backed up by a battery so that it retains data necessary for subsequent engine operation even if a key switch (not shown) is turned off. 25 is an input port (not shown), a waveform shaping circuit provided as necessary, a multiplexer that selectively outputs the output signal of each sensor to the CPLI 21,
A/D converter that converts analog signals to digital signals,
, etc., respectively. Reference numeral 26 denotes an input/output section which is provided with an output port in addition to an input port (not shown), and is also provided with a drive circuit etc. for driving the fuel injection valve 6, igniter 16, etc. according to control signals from the CPU 21 as necessary; 27 is CPU21, ROM2
The path lines connecting each element such as No. 2, the input section 25, and the input/output section 26 and through which various data are sent are respectively shown.

In the engine control device of this embodiment having the above configuration, the fuel injection valve 6 is opened/opened depending on the operating state, and the igniter 1 is
Next, the fuel injection control for controlling the opening time of the fuel injection valve 6, which is the main process according to the present invention, will be controlled according to the flowchart shown in FIG. I will explain.

As shown in the figure, when the process starts, first step 10
1, read the detection signals from each sensor above,
The process moves to the next step 102. In step 102, the fuel injection time τe is calculated based on the detection signals from each sensor read in step 101 above.

Here, the process of step 102 corresponds to the fuel injection time calculation means M3, and in this embodiment, the operation state detection means M
2 as oxygen sensor 5, intake temperature sensor 8, water temperature sensor 9
, throttle position sensor 11, air 70 meter 1
4. Since it has the rotation speed sensor 18, etc., the basic fuel injection time is calculated using the intake air amount Q and engine rotation speed NE, which are determined based on the detection signals from the air 70 meter 14 and the rotation speed sensor 18, as parameters, and then Based on the detection signals from the other sensors, the fuel injection time τe is calculated by performing intake temperature correction, warm-up glabellar correction, starting ground rotation correction, acceleration increase correction, air-fuel ratio feedback correction, etc.

Next, in step 103, the battery voltage B of the vehicle is detected, and in the subsequent step 104, the fuel injection valve is corrected according to the battery voltage using a map or arithmetic expression as shown in FIG. 6 using this battery voltage B as a parameter. 6, the invalid injection time τvb is calculated.

In the subsequent step 105, the above step 104 is performed using a map or arithmetic expression as shown in FIG.
A correction coefficient K for the invalid injection time τvb determined in is calculated, and the process proceeds to step 106.

Here, the map for determining the invalid injection time τvb used in step 104 is a conventionally known map, and when the battery voltage becomes low, the fuel injection valve 6
The invalid injection time is set in consideration of the fact that it takes a long time from when the fuel injection valve receives a drive signal until it actually starts injecting fuel.

On the other hand, in the map for calculating the correction coefficient K used in step 105, as mentioned above, the fuel injection time from the fuel injection valve 6 does not correspond to the valve opening time of the fuel injection valve 6;
The correction coefficient K is set in advance in consideration of the fact that a large error occurs in a low flow rate region, and the correction coefficient K is set so as to exactly cancel out the error shown in FIG. 2.

Next, in step 106, the actual value of the fuel injection valve 6 is An invalid injection time τ■ corresponding to the actual invalid injection time is calculated, and the process proceeds to step 107.

Then, in step 107, the invalid injection time τV and the fuel injection time τe obtained in step 102 are added to calculate the opening time τ of the fuel injection valve 6, and the process proceeds to step 108. do.

In step 108, it is determined whether or not it is the current fuel injection timing, and if it is the fuel injection timing, step 10
At step 9, a drive signal is output to the fuel injection valve 6 for the valve opening time τ determined at step 1.7, and if it is not the fuel injection timing, the process of this routine is immediately terminated.

Note that steps 104 to 107 correspond to the invalid injection time calculation means M5, and steps 108 and 109 correspond to the fuel injection valve driving means M6.

In this way, in the fuel injection control device of this embodiment, the invalid injection time τ■ of the fuel injection valve 6 is set not only according to the battery voltage but also the fuel injection time τe, and the valve opening time τ of the fuel injection valve 6 is set according to the fuel injection time τe. I'm trying to find out. Therefore, even in an extremely low flow rate range, the amount of fuel injected from the fuel injection valve 6 can be controlled to an optimal value depending on the operating condition, and exhaust gas purification can be improved.

In the above embodiment, the invalid injection time τ■ is determined by the battery voltage B
It is determined by correcting the invalid injection time τvb determined according to the fuel injection time τe using a correction coefficient K determined based on the fuel injection time τe. A three-dimensional map consisting of the voltage B' and the invalid injection time τ is stored in the ROM 22 in advance, and this map is used to determine the fuel injection time τe.
Invalid injection time τ with and battery voltage B as parameters
It is also possible to calculate V. Furthermore, since the battery voltage B decreases and the invalid injection time becomes longer when the engine is started, the invalid injection time should be set based on the fuel injection time required depending on the operating condition during normal engine operation. You can. The map in this case is as shown in FIG.

[Effects of the Invention] As described in detail above, in the fuel injection control device for an internal combustion engine of the present invention, the ineffective injection time of the fuel injection valve is divided into one fuel injection time determined according to the operating state of the internal combustion engine. The fuel injection valve is determined as a parameter, and the fuel injection valve is driven and controlled using the time obtained by adding the determined invalid injection time and the fuel injection time. Therefore, even in a low fuel flow range where the fuel injection amount does not correspond to the fuel injection valve opening time, the error can be absorbed by the invalid injection time, and fuel can be supplied to the internal combustion engine only as long as it is needed. Can be done. Furthermore, since the fuel supply amount can be optimally controlled, the air-fuel ratio also becomes the target air-fuel ratio, making it possible to effectively utilize the three-way catalyst, thereby preventing deterioration of exhaust components.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of the present invention, FIG. 2 is a graph explaining the conventional problem, FIGS. 3 to 7 show an embodiment of the present invention, and FIG. A schematic system diagram showing the engine and its peripheral equipment, FIG. 4 is a block diagram showing the electronic control circuit, FIG. 5 is a flowchart showing the control program for fuel injection control executed in the electronic control circuit, and FIG. 6 is the step Invalid injection time τvb at 104
Fig. 7 is a diagram showing a map used in calculating the correction coefficient K of the invalid injection time τvb in step 105. Figs. 8 and 9 are diagrams showing the map used in calculating the invalid injection time τvb. Other examples of maps used in determining the time τ■ are shown; FIG. 8 is a diagram representing a three-dimensional map consisting of the battery voltage B, fuel injection time τe, and invalid injection time τ■, and FIG. 9 is a diagram showing the fuel injection time τe. Injection time τe and invalid injection time τ■
It is a line diagram showing a two-dimensional map consisting of. Ml...Internal combustion engine M2...Operating state detection means M3...Fuel injection time calculation means M4.6...Fuel injection valve M5...Invalid injection time calculation means M6...Fuel li injector drive Means 20...Electronic control circuit 21...CPU 22...ROM 23...RAM

Claims (1)

[Scope of Claims] Operating state detection means for detecting the operating state of the internal combustion engine; fuel injection time calculation means for calculating the fuel injection time based on the detected operating state of the internal combustion engine; an invalid injection time calculation means for calculating an invalid injection time of a fuel injection valve with injection time as one parameter; A fuel injection control device for an internal combustion engine, comprising: a fuel injection valve driving means for outputting a fuel injection valve;