JPH063154B2 - Fuel injection control device for internal combustion engine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a fuel injection control device for an internal combustion engine, and in particular, at the time of starting by controlling the fuel injection start timing of a cold start injection valve (hereinafter referred to as STJ). The present invention relates to a fuel injection control device that improves emission by preventing an increase in hydrocarbon (HC) and carbon monoxide (CO) due to fuel adhering to the wall surface of an intake system.

[Conventional technology]

Generally, the STJ drive used at cold start is a starter injector time switch (TZS) which is a mechanical timer equipped with a bimetal with a heater as shown in FIG.
Controlled by. In this case, starter switch (ST
When the A / SW) is turned on, the STJ is energized when the bimetal contact is in contact and the STJ starts fuel injection, but when the engine cooling water temperature around the bimetal B reaches the set temperature of the TZS bimetal, The contact is separated and the STJ is not energized, and the injection of 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 by a heat generation of the heat coil HC after a lapse of a predetermined time so that the STJ is not energized for a predetermined time or longer. In this way, the maximum drive time (J) of TZS is set according to the set temperature T ₁ or T ₂ of TZS, for example, in the relationship shown in T _{1 to} a ₁ or T _{2 to} a ₂ in FIG. In this case, set the starter switch (STA / SW) of STJ to OF at any set temperature.
If it is set to F, the drive of STJ can be stopped in a time shorter than the drive time of TZS.

[Problems to be solved by the invention]

The conventional control method using the mechanical timer TZS as shown in FIGS. 12 and 13 has the following problems. That is, when the set temperature of TZS is T ₂ , the bimetal B is in contact and the starter switch (STA / SW) is turned on.
At the same time when it is set to N, STJ starts fuel injection.

However, in this case, since the engine enters cranking and the fuel injection by the STJ is performed earlier than the intake airflow is generated in the intake pipe, the fuel adheres to the wall surface of the intake system and the emission (HC, CO)
There was a problem that deteriorated.

[Means and Actions for Solving Problems]

The present invention relates to a fuel injection control device for controlling the fuel injection timing of a cold start injection valve of an internal combustion engine, which solves the above-mentioned problems, and to drive a control switch and a starter switch for controlling the opening and closing of the cold start injection valve. A control means for controlling ON / OFF of the control switch according to a state is provided, and the control means turns on the control switch after a lapse of a predetermined time after the starter switch is turned on, and the cold start injection valve Is controlled so that the fuel injection is started to start the fuel injection. As an example, opening and closing of the cold start injection valve (STJ) is performed by a mechanical timer (TZS) and an electronic control unit (EC).
In a fuel injection control device controlled by U), STJ
The first control switch (TZS) for controlling the opening / closing of the STJ and the second control switch connected in parallel for controlling the opening / closing of the STJ independently of the TZS are provided, and the first control switch is, for example, 20 ° C. The specification is such that the STJ is opened at an extremely low set temperature T ₁ or lower, and at a high temperature higher than the set temperature T ₁ , the ON timing of the second control switch is set based on the engine speed and the elapsed time of the starter switch ON.
An object of the present invention is to provide a fuel injection control device capable of improving startability and emission by being controlled by an ECU.

FIG. 1 shows an example of the configuration of the present invention for achieving the above object. Referring to FIG. 1, a fuel injection control device according to the present invention includes a first control switch a and a second control switch b.
And an elapsed time detecting means c after the starter switch is turned on,
The starter drive state detecting means d and the engine speed detecting means e are provided. 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 shown in the figure.
The first control switch a is a bimetal g and a heat coil h.
And i and have contacts j and k. The bimetal g is designed so that the contacts j and k are brought into contact with each other when the engine cooling water temperature is equal to or lower than the _first set temperature T ₁ , and the starter switch (STA) is provided while the contacts j and k are brought into contact with each other at the time of starting.・ When SW) is turned ON, the solenoid of STJ f
A current flows through STJ to open the valve and inject fuel. Also, T ₁
Even in the following cases, the bimetal g is heated by the heat coils h and i, so that the contacts are separated after a predetermined time and the fuel injection 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 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 / closing of the STJ independently of the first control switch a according to a control flow by a control means described later.

The elapsed time detecting means c is a starter switch (STA / S
It detects that a predetermined time has elapsed after W) is turned on and outputs an elapsed time detection signal T.

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 ER when the engine is in the speed range of a predetermined range.

The AND gate is opened by the coincidence of the elapsed time detection signal T, the starter drive detection signal SD and the engine speed detection signal ER, and the power transistor PTr is turned on.
By controlling each of the detecting means c to d according to a control pattern described later, the ON timing of the second control switch b is controlled and the drive start timing of the STJ is controlled.

Further, the engine cooling water temperature is higher than the first set temperature and the second
Further includes engine cooling water temperature detection means for outputting a water temperature detection signal in a temperature range lower than the set temperature, and the second control switch controls the ON timing within the set temperature range to turn on the cold start injection valve. Open the valve.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings starting from FIG.

FIG. 2 is a system diagram of an embodiment of the fuel injection control device according to the present invention. In FIG. 2, 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, 11 is a distributor, 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 drive timing is controlled by the second control switch b whose on / off is controlled by the electronic control unit 16 as the control means. The rotation angle sensor 13 outputs a pulse signal proportional to the rotation speed of the engine.

FIG. 3 is a detailed block diagram of the electronic control unit (ECU) 16 shown in FIG. In FIG. 3, an ECU 16 is a central processing unit (CPU) 31 composed of microprocessors which are interconnected via a bus line BUS, and A which converts an analog signal from each sensor into a digital signal.
/ D converter 32, 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 (scan rotation) Number) is input to the input interface circuit 33. Based on these signals, they are processed by the CPU 31 as shown in a control flow described later, and are output to the fuel injection valve, the igniter, and the STJ to drive them.

FIG. 4 is a diagram showing the relationship between the STJ drive time and the engine speed of the fuel injection control device according to the present invention. In the present invention, after the starter switch is turned on at the set temperature T ₁ or higher, after a predetermined time B has passed, the STJ is energized to start the injection at the timing when the engine enters the cranking and the injection is continued for the predetermined time A. In B, the STJ is not driven because the intake airflow does not exist in the intake pipe. About 100 msec is suitable for this delay time B.

FIG. 5 shows the relationship between the STJ drive time (A) and the engine cooling water temperature THW according to the present invention. t ₁ is t in FIG.
It corresponds to ₁ and is the time when the STJ starts driving. As is apparent from the figure, at the set temperature T ₁ or higher, the drive start timing of STJ is delayed by t ₁ .

FIG. 6 is a control flowchart of one embodiment of the fuel injection control device according to the present invention, which is a control flow performed based on the engine speed. In FIG. 6, first,
The starter switch ON / OFF is judged by the starter signal (y
It is determined by whether or not (STA) is included (step 1). When the starter signal is not input, the STJ operation flag fSTJ = 0 and STJ does not operate (step 5). When the starter signal is input and cranking is in progress, the engine speed NE is the first set value A (for example, 10
(0 rpm) or higher (step 2). If NE is A or higher, then it is determined whether or not the second set value C (400 rpm, for example) or higher (step 3). If NE is C or less, S
Since the TJ operation flag fSTJ = 1, the STJ starts the operation (step 4). On the other hand, if NE is equal to or less than A or equal to or more than C, fSTJ = 0 and STJ stops its operation (step 6). Here, the set values A and C are A <C. As is clear from the above description, when the starter switch is ON, if the engine speed is within a predetermined set value range, that is, if A <NE <C, STJ is operated. That is, the STJ drive time A shown in FIG. 4 is controlled.

FIG. 7 is a control flowchart of another embodiment of the fuel injection control device according to the present invention, which is a control flowchart performed based on the elapsed time after the starter switch is turned on and the engine speed. In FIG. 7, the starter switch ON / OFF is first determined by the starter signal (ySTA).
It is determined whether or not is included (step 1). When the starter signal is input and the cranking is started, the timer for measuring the STJ operation time starts counting and the flag TSTJ indicating the count value has a predetermined elapsed time value A (for example, 100 msec).
It is determined whether or not the above (step 2). If TSTJ is A or higher, then it is determined whether the engine speed NE is B or higher (step 3). If NE is B or less, STJ operation flag fSTJ = 1 and STJ operates. See also TSTJ
Is less than A or NE is more than B, fSTJ =
It becomes 0 and the operation of STJ is stopped (step 7). On the other hand, when the starter signal is not input in step 1, the RAM of the counter for measuring the STJ operation time is cleared (step 5), and the STJ operation flag is cleared (step 6).

FIG. 8 is a flowchart of the count value of the counter in the control of FIG. This counter counts up every 4 msec, and the starter switch is O
When it is N, counting is started and the contents of TSTJ are put into the A register (step 1). Next, the contents of A + 1 are put into the A register (step 2), and the contents of the A register are put into TSTJ (step 3).

FIG. 9 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 the STJ is performed by the second control switch b. The ON / OFF of the control switch b is controlled based on the detection signals from the elapsed time detecting means c, the starter drive state detecting means d, and the engine speed detecting means e as in the first embodiment. In this case, the engine cooling water temperature (THW) is determined for the set temperatures T ₁ and T ₂ by a separate means.

FIGS. 10 (a) and 10 (b) are diagrams showing still another configuration example of the present invention. In this embodiment, the starter switch STA is shown.
・ In order to delay the drive timing of STJ for a predetermined time after turning on SW, resistor R and capacitor C are used in the example picture (a).
Is provided between TZS and STA / SW. Further, in (b), a transistor Tr is added to reduce the load on the resistor R and enhance the durability. With such a configuration, the predetermined delay time, for example, 100 msec, causes a time constant RC.
Can be set by appropriately selecting. If this circuit is used, the configuration can be simplified and the cost can be reduced.

FIG. 11 is a graph showing the effect of the present invention. In the conventional STJ drive time pattern shown in FIG. 12, when the operating temperature of TZS is T ₂ , the emission of HC and CO becomes like the curve A, and the emission deteriorates. Further, in the conventional method, since the STJ was driven at the same time when the starter switch was turned on, the emission was deteriorated as shown by the curve A. On the other hand, in the present invention, when the STJ is driven, the engine speed or the elapsed time after the starter switch is turned on is monitored and the STJ is driven after a predetermined time delay, so that the fuel adhesion on the wall surface of the intake system is prevented and the curve B is obtained. Emissions can be improved.

〔The invention's effect〕

According to the fuel injection control device of the present invention, the fuel injection timing of the cold start injection valve is controlled to be delayed by a predetermined time based on the engine speed or the elapsed time after the starter switch is turned on. The fuel is injected after the air flow is generated in the system, which can prevent the fuel from adhering to the wall surface of the intake system and improve the emission.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of a fuel injection control device according to the present invention, FIG. 2 is a system diagram of an embodiment of the present invention, FIG. 3 is a detailed block diagram of an electronic control device, and FIG. FIG. 5 is a relationship diagram between engine speed and elapsed time according to FIG. 5, FIG. 5 is a relationship diagram between STJ drive time and engine cooling water temperature of the present invention, FIG. 6 is a control flowchart of one embodiment of the present invention, and FIG. FIG. 8 is a counter flowchart, FIG. 9 is a configuration diagram of another embodiment of the present invention, and FIGS. 10A and 10B are configuration diagrams of yet another embodiment of the present invention. FIG. 11 is a graph showing the effect of the present invention, FIG. 12 is a configuration diagram of a conventional system, and FIG. 13 is a relationship diagram of STJ maximum drive time and engine cooling water temperature in the conventional system. (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 unit, 17 ... Throttle Valve opening sensor, 18 ... Intake air temperature sensor, 19 ... Oxygen sensor.

Claims (1)

[Claims] 1. A fuel injection control device for controlling a fuel injection timing of a cold start injection valve of an internal combustion engine, wherein the control is performed in accordance with drive states of a control switch and a starter switch for controlling opening / closing of the cold start injection valve. A control means for controlling on / off of the switch is provided, and the control means turns on the control switch after a predetermined time elapses after the starter switch is turned on to open the cold start injection valve to inject fuel. 1. A fuel injection control device for an internal combustion engine, characterized in that control is performed so as to start.