JPH063155B2 - Fuel injection control device for internal combustion engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection control device for an internal combustion engine, and particularly to a cold start injection valve (hereinafter referred to as STJ) by controlling fuel injection timing and time. Of hydrocarbons (HC) and carbon monoxide (CO) due to fuel adhering to the wall surface of the intake system at the time of emission, and smoldering of the spark plug due to excessive fuel and deterioration of startability due to poor fuel to prevent emissions. The present invention relates to an improved fuel injection control device.

[Conventional technology]

Generally, the drive of STJ used at cold start is controlled by a starter injector time switch (TZS) which is a mechanical timer equipped with a bimetal with a heater as shown in FIG. In this case, the starter switch (STA ・ S
When W) is turned on, STJ is energized when the bimetal contact is in contact, STJ starts fuel injection, but when the engine cooling water temperature around bimetal B reaches the set temperature of the bimetal of TZS, bimetal B The contacts are separated and the STJ is no longer energized, and the injection of the STJ is stopped. Further, when the engine cooling water temperature is equal to or lower than the set temperature, the contact of the bimetal B is separated after a lapse of a predetermined time due to heat generation of the heat coil HC, and control is performed so that STJ is not energized for a predetermined time or longer. As described above, the maximum drive time (J) of TZS is set in a linear relationship as shown by T _{1 to} a ₁ or T _{2 to} a ₂ in FIG. 11 depending on the set temperature T ₁ or T ₂ of TZS. It In this case, the STJ starter switch (STA / S
If (W) is turned off, ST is started in a time shorter than the drive time of TZS.
It is also possible to stop the driving of J.

[Problems to be solved by the invention]

Conventional mechanical timer TZ shown in FIG. 10 and FIG.
The control method by S has the following problems. That is, as shown in FIG. 6, the engine cooling water temperature is set to T ₁ , for example, 20 ° C.
When set to, STJ will not drive at T ₁ or higher, but
As shown by the white mark, when using poor fuel with low lead vapor vapor pressure, it will take time for the complete explosion of the engine. That is, the startability of the engine is extremely deteriorated, and T
_If it is ₁ or less, it takes 1 to 2 seconds to start up to 5 to 6 seconds. Further, at the set temperature T ₁ , the engine cooling water temperature may be T ₁ or higher for a long period of summer when the temperature is high, which causes a problem such as STJ not being driven and sticking to clog the injection port.

As a method of solving these problems, it is conceivable to raise the set temperature of STJ to T _2, but in this case, the engine start time becomes about 1.5 seconds as shown by the black mark, which is a significant improvement and a problem. However, if the starter is turned on even after the start, the STJ will be driven until the maximum drive time of the TZS and fuel will be injected unnecessarily. Even with normal fuel, HC, CO Emission, that is, deterioration of emission will be caused.

On the other hand, Japanese Patent Laid-Open No. 60-22045 discloses an example in which the TZS and the computer (CPU) drive the STJ in parallel, but the STJ CPU is driven for a very short time (20 ms).
ec) is performed only for the purpose of preventing STJ sticking, and does not mention the STJ drive time that can prevent deterioration of startability due to poor fuel in a temperature range higher than the set temperature T _{1 of} TZS.

[Means and Actions for Solving Problems]

The present invention is a fuel injection control device for an internal combustion engine that solves the above-mentioned problems, and as shown in the basic configuration diagram of the present invention in FIG. 1, a fuel injection control for controlling the fuel injection for starting the internal combustion engine. A device, a starter drive state detection means X for determining whether or not the starter is driven, and a starter drive state detection means for detecting that the starter has changed from a non-operating state to an operating state, and from the detection time point. And a clock means for counting the elapsed time, and instructing the fuel injection for starting when the elapsed time by the clock means is equal to or longer than a first predetermined time, and the elapsed time is greater than the first predetermined time. A start-up control means for prohibiting the fuel injection for start-up for a second predetermined time or longer is provided, and as an example, opening and closing of the cold-start injection valve (STJ) is performed by a mechanical timer. ( In a fuel injection control device controlled by ZS) and an electronic control unit (ECU), opening / closing of STJ is controlled independently of a first control switch (TZS) for controlling opening / closing of STJ and TZS connected in parallel therewith. A second control switch is provided, and the first control switch operates at a relatively low set temperature T ₁ below 20 ° C.
With the specification that J is opened, the STJ drive upper limit time is set by controlling the second control switch controlled by the ECU to drive the STJ for a predetermined time, for example, for 2 seconds at a high temperature equal to or higher than the set temperature T _1. By doing ST
It is an object of the present invention to provide a fuel injection control device that prevents smoldering of a spark plug due to excessive J drive, improves emission, and improves startability when poor fuel is used.

FIG. 2 shows a structural example of the present invention for achieving the above object. Referring to FIG. 2, the fuel injection control device according to the present invention includes a first control switch a and a second control switch b.
An engine cooling water temperature detecting means c, a starter drive state detecting means d, and an engine speed detecting means e. A solenoid f for controlling the opening and closing of the STJ is provided, and the solenoid f is connected to the first control switch a and the second control switch b as illustrated. The first control switch a is composed of a bimetal g and heat coils h and i, and has contacts j and k. The bimetal g is designed so that the contacts j and k are in contact with each other when the engine cooling water temperature is equal to or lower than the _first set temperature T ₁ , and as described above, the contacts j and k are in contact with each other at the time of starting. During this period, when the starter switch (STA / SW) is turned on, a current flows through the solenoid f of the STJ and the STJ opens to inject fuel. Further, even if T ₁ or less, the bimetal g is heated by the heat coils h and i, so that the contact is separated after a predetermined time and the fuel injection of STJ is stopped. On the other hand, when the engine cooling water temperature becomes higher than the set temperature T ₁ , the contacts j and k are separated from each other, but the drive of the STJ is independently controlled by the second control switch b as described later.

The second control switch b is connected in parallel to the first control switch a, and controls the opening and closing of the STJ independently of the first control switch a according to a control flow described later.

The engine cooling water temperature detection means c outputs a water temperature detection signal WT when the temperature of the engine cooling water is in a range higher than the set temperature T _{1 and} lower than the set temperature T ₂ .

The starter drive state detection means d detects whether or not the starter switch for driving the starter motor is in the on state, and outputs the starter drive detection signal SD when in the on state.

The engine speed detection means e outputs an engine speed detection signal RE when the engine is in the speed range of a predetermined range.

When the water temperature detection signal WT, the starter drive detection signal SD, and the engine speed detection signal RE coincide with each other, the AND gate is opened and the power transistor PTr is turned on, so that a current flows through the second control switch b, the switch b is turned on, and STJ is To jet. In addition, an elapsed time detecting means for detecting the elapse of a predetermined time after the starter switch is turned on is further provided, and the second control switch is turned on within the range of the elapsed time to drive the STJ.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS.

FIG. 3 is a system diagram of one embodiment of the device for controlling fuel injection according to the present invention. In FIG. 3, 1 is an air cleaner, 2
Is an air flow meter, 3 is a throttle valve, 4 is an intake passage, 5 is a cold start injection valve, 6 is a fuel tank, 7 is a fuel pump, 8 is a fuel injection valve, 9 is an ignition coil, 10 is an igniter, and 11 is a distributor. A viewer, 12 is a cylinder discrimination sensor, 13 is a rotation angle sensor, 14 is a spark plug, 14a is a combustion chamber, 15 is a water temperature sensor, a is a first control switch,
Reference numeral 16 is an electronic control device, 17 is a throttle valve opening sensor, 18 is an intake air temperature sensor, 19 is an oxygen sensor, and b is a second sensor.
Control switch.

In such a configuration, the cold start injection valve (STJ) 5 provided in the surge tank of the intake passage 4 includes the first control switch a provided near the water temperature sensor 15 of the cylinder block of the engine body. The second control switch b whose ON / OFF is controlled by the electronic control unit 16 controls the drive timing and time in the drive time pattern of FIG. The rotation angle sensor 13 outputs a pulse signal proportional to the rotation speed of the engine.

FIG. 4 is a detailed block diagram of the electronic control unit (ECU) 16 shown in FIG. In FIG. 4, an ECU 16 includes a central processing unit (CPU) 31 composed of microprocessors interconnected via a bus line BUS, an A / D conversion converter 32 for converting an analog signal from each sensor into a digital signal, Input interface circuit 33, output interface circuit 34, read only memory (ROM) 35, random access memory (RAM) 3
6, and a constant voltage power supply 37 are provided.

In such a configuration, the battery voltage (+ B), the airflow output, the intake air temperature (THA) output, and the engine water temperature sensor output (THW) are analog / digital converted by the A / D converter 32, and the starter signal and the distributor signal (engine rotation Number) is input to the input interface circuit 33. Based on these signals, it is processed by the CPU 31 as shown in the control flow described later and is output to the fuel injection valve, the igniter, and the STJ to drive them.

FIG. 5 shows the relationship between the STJ drive time (J) and the engine cooling water temperature (THW) of the fuel injection control device according to the present invention, and FIG. 6 shows the engine complete explosion time (starting time) and the engine cooling water temperature ( THW). In FIG.
T _{1 to} a ₁ are the case where the TZS set temperature T ₁ is low and the tenth
This is equivalent to the STJ drive only by TZS shown in the figure, and as described above, the engine cooling water temperature is T ₁ (for example, 20
When bad fuel is used in the range where TZS is not higher than ℃), the startability may deteriorate as shown by the white mark in Fig. 6, and even with normal fuel, the emission deteriorates due to excess fuel. Sometimes. T _{2 of} FIG.
a ₂ is the case where the TZS set temperature is higher than T ₁ , and for example, when the set temperature is T ₂ = 40 ° C., the complete explosion time is 2 seconds or less even with poor fuel, as shown in FIG. There is no deterioration. However, in this case, unless the starter switch is turned off at the time of starting, STJ is T ₂ ~ as shown by the dotted line.
would be driven along a straight line of a _2, which causes the deterioration of the emission at the start at room temperature becomes a fuel excessive.
Therefore, in the present invention, the control of the STJ drive time pattern is performed as shown by the solid line in the figure so as to prevent the emission from deteriorating due to excessive fuel at the set temperature T ₁ or higher and to improve the startability even when poor fuel is used. To do. That is, S
The maximum driving time of TJ is controlled so as to be the upper limit (for example, 2 seconds) with the line of C _{3 to} C ₄ shown by the solid line. In addition, a C ₁ -C ₂ line (for example, 100 mse) showing the STJ drive timing by a solid line so as to drive the STJ after the intake airflow is generated in the intake passage.
c) Control to start above.

As is apparent from the above description, the control of the STJ drive time is performed by TZS in the left range of T _{1 to} a ₁ , and the range of C _{1 to} C _{2 to} C _{3 to} C ₄ is in the electronic control unit (ECU). ) 16. That is, the control of the STJ drive time according to the present invention is a _{1 to} C _{4 to} C _{3 to} C.
The range is from _{2 to} C _{1 to} T ₁ . Of course, even within the above range, the STJ is stopped when the rotation speed exceeds the start determination rotation speed or when the starter switch is turned off, as described later.

FIG. 7 shows a control flowchart of the fuel injection control device according to the present invention. The STJ drive time pattern of FIG. 5 can be obtained from this control flowchart. In FIG. 7, first, is the flag FSTA indicating the starting state ON?
It is determined whether it is OFF (step 1). When FSTA is ON,
When the FSTA is turned on for the first time, the STJ operation time timer STJJ is set and counting is started (step 2). Next, the engine rotation speed is the first start determination rotation speed N ₁
It is determined whether (for example, 400 rpm) is exceeded (step 3). If it exceeds, FSTA is turned off (step 4) and control is not performed and the process ends. If it does not exceed, it is determined whether the engine cooling water temperature (THW) is equal to or lower than the second set temperature T ₂ (step 5). If THW is T ₂ or more, control is not performed and the process ends. When THW is T ₂ or less, it is next determined whether or not Kunter STJJ is larger than J ₁ (step 6). Here, J ₁ is the time (counter value) until the intake airflow is generated as shown in FIG. When STJJ is larger than J _1, it is next judged whether or not it is smaller than J ₂ (step 7). Here, J ₂ is similarly the STJ maximum drive time (counter value) between the set temperatures T ₁ and T ₂ as shown in FIG. Based on the judgments in steps 5, 6 and 7, it is judged whether or not it is within the STJ operation range as shown in FIG. 5 (step 8). If it is outside the operating range of STJ, it ends, and if it is within the range, STJ is turned on (step 9). This drives the STJ so that the second
The power transistor PTr shown in the figure is turned on and the second control switch b is turned on to drive the STJ and inject fuel.

On the other hand, when the starting state plug FSTA is OFF in step 1, it is determined whether the ignition flag FIg is ON or OFF to determine whether the engine is in the operating state (step 1
0). When OFF, the STJJ counter set in step 2 is reset (step 11), and the same control as when ON is performed. When the ignition flag FIg is ON, the engine speed is the second starting speed N ₂ (for example, 30
It is determined whether or not the speed exceeds 0 rpm (step 12).
When the rotation speed is lower than N ₂ , it means that the engine is in the starting state, so the starting state flag FSTA is turned on (step 13), and the rotation number is N.
_If it exceeds ₂ , it ends.

FIG. 8 is a diagram showing another configuration example of the present invention. As is apparent from the figure, the first control switch a used in the first embodiment is removed and the opening / closing drive of STJ is performed by the second control switch b. ON / OFF of control switch b is the first
Similar to the embodiment, the control is performed based on the detection signals from the engine cooling water temperature detecting means c, the starter drive state detecting means d, and the engine speed detecting means e. As the control in this case, the determination of the engine cooling water temperature (THW) in step 5 in the flowchart of FIG. 7 is also performed for the set temperature T ₁ .

FIG. 9 is a graph showing the effect of the present invention. In the conventional STJ drive time pattern shown in FIG. 11, when the set temperature of TZS is T ₂ , HC and CO emissions are in a state as shown by curve A due to excessive fuel, and the emission is deteriorated. Further, when the TZS operating temperature is set to T ₁ , STJ does not operate at T ₁ or higher, so that a curve C is obtained. That is, in the conventional method, when the TZS set temperature is set to T ₂ , STJ is driven for the maximum operation time of TZS even if the starter switch is ON even if the engine has completed the start-up, and a large amount of extra fuel is ejected to form curve A. Become. Further, when the operating temperature is set to T ₁ , STJ is not driven at a temperature higher than this in the conventional method, and the curve C is obtained.

On the other hand, in the STJ drive according to the present invention, the completion of the engine start is monitored by the engine speed, and even if the starter switch is ON, the STJ drive is immediately interrupted if it is determined that the start is completed, so that no extra fuel is ejected. . In this case, as shown in FIG. 5, the upper limit is set for the drive time of STJ, so that the emission of HC and CO becomes curve B. In this way, the emission ratios of HC and CO are A>B> C, but the C curve is the case where the STJ is not driven, and the invention shown in the curve B is the most advantageous when considering the startability.

〔The invention's effect〕

According to the fuel injection control device of the present invention, the opening / closing of the cold start injection valve is controlled by the starter injector timer and the electronic control device or only the electronic control device so as to form the STJ drive time pattern with a predetermined upper limit. It is possible to prevent smoldering of the spark plug due to excessive STJ drive at the time of start-up, to improve emission, and to improve startability when using poor fuel.

[Brief description of drawings]

1 is a basic configuration diagram of the present invention, FIG. 2 is a configuration diagram of an embodiment of a fuel injection control device according to the present invention, FIG. 3 is a system diagram of an embodiment of the present invention, and FIG. 4 is an electronic control device. FIG. 5 is a detailed block diagram of FIG. 5, FIG. 5 is a diagram showing a relationship between STJ drive time and engine cooling water temperature in the present invention, FIG. 6 is a diagram showing a relationship between engine complete explosion time and engine cooling water temperature, and FIG. FIG. 8 is a configuration diagram of another embodiment of the present invention, FIG. 9 is a graph showing the effect of the present invention, FIG. 10 is a configuration diagram of a conventional system, and FIG. 11 is a diagram of a conventional system. It is a figure which shows the relationship between STJ drive time and engine cooling water temperature. (Description of symbols) STJ ... Cold start injection valve, TZS ... Starter injector switch, 1 ... Air cleaner, 2 ... Air flow meter, 3 ... Throttle valve, 4 ... Intake passage, 5 ... STJ, 6 ... Fuel tank, 7 ... Fuel pump, 8 ... Injector, 9 ... Ignition coil, 10 ... Igniter, 11 ... Distributor, 12 ... Cylinder discrimination sensor, 13 ... Rotation angle sensor, 14 ... Spark plug, 15 ... Water temperature sensor, 16 ... Electronic control device, 17 ... Throttle valve opening sensor, 18 ... Intake air temperature sensor, 19 ... Oxygen sensor.

Claims (1)

[Claims] 1. A fuel injection control device for controlling fuel injection for starting an internal combustion engine, comprising starter drive state detection means for determining whether or not a starter is driven, and starter drive state detection means for starting the starter. Means for detecting the change from the non-operating state to the operating state and counting the elapsed time from the detection time point, and the fuel injection for starting when the elapsed time by the clock means is a first predetermined time or more And a starting control means for prohibiting the fuel injection for starting when the elapsed time is equal to or longer than a second predetermined time that is longer than the first predetermined time. Fuel injection control device.