JPH09105344A - Fuel injection controller of engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain the generation of unburnt gas just after engine starting as well as to aim at a reduction in exhaust gas by seeking a span of current- energization time for a solenoid valve of an injector conformed to the prescribed injection quantity necessary for the start of an engine, from engine speed and fuel pressure with a memory map. SOLUTION: A controller 10 reads those of engine speed, fuel pressure, cooling water temperature, intake air and atmospheric pressure from each of sensors 12 to 16 at a time when a driver turns a key switch to ON to start an engine. In addition, when a starter switch 11 is turned to ON, a basic target injection quantity (energizing time) is read out of a memory map on the basis of the engine speed and the fuel pressure. Then a water temperature correcting factor to this basic target injection quantity is read out of the memory map, while a correction factor having taken air density into account is read out of the memory map, calculating the target injection quantity with these correction factors. Subsequently this target injection quantity is given to an injector 6 and thereby fuel is sprayed to an intake system of the engine.

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine fuel injection control device, and more particularly to a device for controlling an injection amount of fuel supplied from an injector to an engine.

[0001]

2. Description of the Related Art Conventionally, an electronically controlled fuel injection device used in a gasoline engine or the like is shown in FIG. 5, in which a fuel (gasoline) in a fuel tank 1 is sucked up by a low pressure pump 2 and is kept constant. Pressurized to pressure, piping 3a
Through the high pressure pump 4.

This high-pressure pump 4 is for pressurizing fuel to a pressure optimum for supplying it from an injector 6 to an intake system of an engine through a pipe 3b and a fuel rail 5.

The fuel pressurized by the high-pressure pump 4 and given to the fuel rail 5 is given to the high-pressure regulator 7 through the pipe 3c, further given to the low-pressure regulator 8 through the pipe 3d, and returned to the fuel tank 1 through the pipe 3e. It is supposed to be.

That is, the fuel in the fuel tank 1 circulates through the fuel supply system of the low pressure pump 2 → high pressure pump 4 → fuel rail 5 → high pressure regulator 7 → low pressure regulator 8.

While the fuel circulates in the fuel supply system as described above, the high-pressure regulator 7 constituting the high-pressure fuel supply system together with the high-pressure pump 4 and the fuel rail 5 constantly adjusts the pressure of the circulated fuel to a predetermined value. The high pressure fuel, which is being pressurized, is converted to atmospheric pressure by the low pressure regulator 8 and returned to the fuel tank 1.

A pipe 3f is connected from the high-pressure pump 4 to the low-pressure regulator 8, which is the high-pressure pump 4.
Can leak a part of the fuel to the pipe 3b to the side of the pipe 3f to make the fuel pressure (fuel pressure) variable, and the leaked fuel pressure can be returned to the atmospheric pressure by the low pressure regulator 8. There is.

Further, the injector 6 has a solenoid valve (not shown) built therein, and the engine control module (hereinafter sometimes simply referred to as a controller) controls the energization time (that is, the injection amount) of the solenoid valve. By doing so, the injector 6 is opened and closed.

In this case, the controller is basically based on the theoretical A / F (air-fuel ratio) from the engine speed from the speed sensor (not shown) and the intake air amount from the air flow sensor (not shown). The energization time is determined, and correction is made based on the engine temperature from the cooling water temperature sensor (not shown) and the exhaust oxygen concentration from the O ₂ sensor.

[0009]

In the conventional fuel injection control device for an engine as described above, when the engine is in the starting state, the fuel pressure in the fuel rail slightly increases until it reaches a predetermined value adjusted by the high pressure regulator. Since there is a time delay in the actual energization time determined from the engine speed and the intake air amount as described above, the actual injection amount becomes the injection amount required to start the engine due to the low fuel pressure. If it is not satisfied, the engine startability is deteriorated and the amount of unburned HC (hydrocarbon) emission is increased.

In view of this, in Japanese Patent Laid-Open No. 62-129541, it is possible to prevent the above problems by stopping the power supply to the injector until the fuel pressure in the fuel rail reaches a predetermined value when the engine is started. Proposed.

On the other hand, in-cylinder injection (D
In the gasoline engine of type I), the fuel is directly supplied into the cylinder by the injector, so that the injection pressure (fuel pressure in the fuel rail) is set higher than that of the gasoline engine of the intake pipe injection type described in the above publication. There is a need to.

In such a DI type gasoline engine, the fuel pressure increase delay at the time of starting further increases. Therefore, if the technique of the above publication is applied as it is, the energization stop time becomes long, and it takes a long time to start the engine. This also causes a problem that the startability of the engine is deteriorated.

Therefore, it is an object of the present invention to maintain an optimum fuel injection amount at the time of engine start in a fuel injection control device for a gasoline engine which performs in-cylinder injection using an injector.

[0014]

In order to achieve the above object, a fuel injection control device for an engine according to the present invention includes an injector for injecting fuel into a cylinder injection gasoline engine during energization of a solenoid valve. A high pressure fuel supply system for pressure-feeding fuel to the injector, a rotation speed sensor for detecting an engine speed, a fuel pressure sensor provided in the high pressure fuel supply system for detecting a fuel pressure, and a starting state of the engine The detection means and a memory map for obtaining the energization time to the solenoid valve of the injector corresponding to a predetermined injection amount necessary for starting the engine from the engine speed and the fuel pressure are stored in advance in the starting state of the engine. And a controller that determines the energization time from the memory map according to the engine speed and the fuel pressure from each sensor when it is determined that there is. It is characterized in that was.

That is, in the present invention, the controller stores in advance a memory map for obtaining the energization time to the solenoid valve of the injector corresponding to a predetermined injection amount required for engine starting from the engine speed and the fuel pressure. I'll do it.

When the engine starting state detecting means detects the engine starting state, the controller is provided in the high pressure fuel supply system which receives the engine speed from the engine speed sensor and pressure-feeds the fuel to the injector. The fuel pressure from the fuel pressure sensor is input, and the energization time to the solenoid valve of the injector is determined from the stored memory map according to these.

Then, the solenoid valve of the injector, to which the energization time is given, injects fuel into the cylinder injection type gasoline engine during the energization time.

In this way, it is possible to prevent a delay in pressure increase due to a low engine speed during engine startup, to improve engine startup failure, and to prevent deterioration of exhaust gas. .

In the present invention, the controller may further include determining whether or not the fuel pressure has reached a predetermined value in the determination of the engine starting state.

This makes it possible to more reliably determine the starting state of the engine.

[0021]

FIG. 1 shows an embodiment of an engine fuel injection control device according to the present invention. This embodiment and the conventional example shown in FIG. 5 include a fuel rail 5 to a high pressure regulator 7. The point is that the fuel pressure sensor 9 is provided in the pipe 3c leading to. The fuel pressure sensor 9 is not limited to the pipe 3c, but the low pressure pump 2 → high pressure pump 4 → fuel rail 5 →
It may be installed anywhere in the high-pressure fuel supply system (high-pressure pump 4 → fuel rail 5 → high-pressure regulator 7) in the fuel supply system composed of the high-pressure regulator 7 → the low-pressure regulator 8.

FIG. 2 schematically shows an electrical system diagram of the fuel injection control apparatus for an engine according to the present invention, in which the injector 6 is energized by an engine control module (ECM) 10 as a controller. It is controlled by this controller 1
0 is a starter switch 11 to a starter (not shown)
The crank angle signal from the crank angle sensor 12, that is, the engine speed signal, the fuel pressure signal from the fuel pressure sensor 13, and the engine cooling water temperature signal from the water temperature sensor 14. , Input the engine intake air amount signal from the air flow sensor 15,
Then, an atmospheric pressure signal is input from the atmospheric pressure sensor 16.

FIG. 3 shows a flow chart of a control program stored and executed in the controller 10 shown in the electrical system diagram of FIG. 2, and FIG. 4 is used for the flow chart shown in FIG. Various memory maps are shown, and the operation of the embodiment of the engine fuel injection control apparatus according to the present invention shown in FIGS. 1 and 2 will be described below with reference to FIGS. 3 and 4.

First, the controller 10 inputs an output signal of a key switch (not shown) when the driver turns the key switch on (ACC position) when starting the engine (step S1).

Immediately after the key switch is turned on, the controller 10 immediately outputs the engine speed signal N _e from the crank angle sensor 12 and the fuel pressure P _f from the fuel pressure sensor 13.
When the cooling water temperature T _w from the water temperature sensor 14, the intake air amount V _a from the air flow sensor 15, an atmospheric pressure sensor 16
Atmospheric pressure P _a from is read (step S2).

The controller 10 further determines whether or not the starter switch 11 is ON (step S3). When the key switch is ON but the starter switch 11 is OFF, the normal mode is set. Therefore, the process proceeds to step S9, that is, the normal mode, that is,
As described in the conventional example, the processing for determining the basic energization time is performed based on the theoretical A / F from the engine speed and the intake air amount.

On the other hand, when it is found that the starter switch 11 is ON, that is, when it is detected that the engine is in the starting state, the engine speed N _e and the fuel pressure P _f read in step S2. First, the basic target injection amount (energization time) T _inj.BASE is read from the memory map shown in FIG. 4A (step S).
4).

The memory map shown in FIG. 4A is
It is stored in advance in the controller 10 and shows the energization time to the solenoid valve of the injector for obtaining the predetermined injection amount required for engine start. As shown, the engine speed N _e (horizontal axis) ) And the fuel pressure P _f (vertical axis) increase, the energization time becomes shorter, and it can be created by experiments and the like.

The coefficient K1 of water temperature correction for the basic target injection amount T _inj.BASE thus obtained is shown in FIG.
It is read from the memory map shown in (2) (step S
5).

The memory map of FIG. 2B shows the cooling water temperature T _w.
The relationship between (horizontal axis) and the correction coefficient K1 (vertical axis) is shown, and it can be seen that the coefficient K1 decreases as the cooling water temperature T _w gradually increases.

Further, the correction coefficient K2 considering the air density is read from the memory map shown in FIG.

This memory map shows the air flow sensor 15
The correction coefficient K2 for the intake air amount V _a from is obtained by an experiment, and the atmospheric pressure P _a is a parameter, and the intake amount V _a increases as the atmospheric pressure P _a increases.
The correction coefficient K2 is set to be small.

In this way, the target injection amount T is calculated using the correction coefficients K1 and K2 obtained in steps S5 and S6.
_inj is calculated (step S7).

This target injection amount is obtained by _{multiplying the} basic target injection amount T _{inj.BASE obtained} in step S4 by the correction coefficient K1 obtained in step S5 and the correction coefficient K2 obtained in step S6. .

By giving the target injection amount T _inj thus _obtained to the injector 6, the solenoid valve built in the injector 6 is driven and the fuel pressurized from the fuel rail 5 shown in FIG. 1 is driven. Will be injected into the intake system of the engine.

Although the correction coefficients K1 and K2 are used in steps S5 and S6 in the above embodiment, this is a conventional process in the fuel injection control of the engine.

The flow chart shown in FIG. 3 (1)
In step S1 and S3,
Although the starting condition is detected, it is shown in (2) of the same figure.
Thus, between steps S3 and S4,
Fuel pressure P detected by pressure sensor 9 _fIs the set value P_fMIN(For example,
When it is larger than the value adjusted by the high pressure regulator 7)
Proceeds to step S9 on the assumption that the starting state has already been escaped.
If not, go to step S4 only
Is also good.

In this case, the engine start condition is further weighted by the fuel pressure condition. For example, when the engine is restarted immediately after the engine is stopped (the fuel pressure is not reduced), the A / F is set.
Can be prevented from becoming excessively rich.

[0039]

As described above, according to the engine fuel injection control apparatus of the present invention, the energization time to the solenoid valve of the injector corresponding to the predetermined injection amount necessary for starting the engine is set to the engine speed and the engine speed. A memory map for determining from the fuel pressure is stored, and when the engine starting state is detected, the above memory is stored according to the engine speed and the fuel pressure detected by the fuel pressure sensor provided in the high pressure fuel supply system. Since the controller determines the energization time from the map, it is possible to suppress the generation of unburned gas immediately after engine start, reduce exhaust gas, and perform stable engine start.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a fuel supply system in a fuel injection control device for an engine according to the present invention.

FIG. 2 is a block diagram showing an electrical system system in a fuel injection control device for an engine according to the present invention.

FIG. 3 is a flowchart showing a control program stored and executed in the controller shown in FIG.

4 is stored in the controller shown in FIG. 2 and FIG.
6 is a graph showing various memory maps used in the flowchart shown in FIG.

FIG. 5 is a block diagram showing a fuel supply system in a conventional engine fuel injection control device.

[Explanation of symbols]

1 Fuel Tank 5 Fuel Rail 6 Injector 9 Fuel Pressure Sensor 10 Controller (Engine Control Module) 11 Starter Switch 12 Crank Angle Sensor 13 Fuel Pressure Sensor 14 Water Temperature Sensor 15 Air Flow Sensor 16 Atmospheric Pressure Sensor In the drawings, the same symbols indicate the same or corresponding parts. .

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number for FI FI technical display location F02D 45/00 376 F02D 45/00 376C (72) Inventor Hiroyuki Yamada 8 Soil Shelf, Fujisawa City, Kanagawa Prefecture Isuzu Motors Limited Fujisawa Factory

Claims (2)

[Claims] 1. An injector for injecting fuel into a direct injection gasoline engine during energization of a solenoid valve, a high-pressure fuel supply system for pumping fuel to the injector, and a rotational speed for detecting engine speed. A sensor, a fuel pressure sensor provided in the high-pressure fuel supply system for detecting fuel pressure, a starting state detecting means of the engine, and a solenoid valve of the injector corresponding to a predetermined injection amount necessary for starting the engine in advance. A memory map for determining the energization time of the engine from the engine speed and the fuel pressure is stored, and when it is determined that the engine is in the starting state, the memory map according to the engine speed and the fuel pressure from each sensor. And a controller for determining the energization time from the fuel injection control device for an engine. 2. The fuel injection control device for an engine according to claim 1, wherein the controller further includes determining whether or not the fuel pressure has reached a predetermined value in the determination of the engine starting state.