JP2002242735A - Fuel injection control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stable operating state by supplying a proper fuel injection quantity when starting an internal combustion engine in a simplified system configuration not having a temperature sensor. SOLUTION: When starting the internal combustion engine 1, a predetermined fuel injection quantity based on an initialized starting fuel injection pulse width TSTA0 is sequentially increased and supplied by injection in accordance with an elapsed time until an engine speed NE reaches a predetermined engine speed NESTA or higher. By this, when starting the internal combustion engine 1, the fuel injection quantity is supplied by injection in just proportions even in the simplified system configuration not having the temperature sensor, the operating state is stabilized in the starting of the internal combustion engine 1, and as a result, positive starting can be provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection control device for an internal combustion engine, which controls a fuel injection amount when the internal combustion engine is started.

[0002]

2. Description of the Related Art Conventionally, when an internal combustion engine is started, in order to control its operation state, for example, a temperature sensor is provided in the internal combustion engine as an operation state detection sensor, and based on the engine temperature detected by the temperature sensor, 2. Description of the Related Art There has been known an apparatus for supplying a fuel injection amount of an internal combustion engine.

[0003]

As described above, if the system is configured so that the engine temperature is detected using a temperature sensor, the fuel injection at the time of starting the internal combustion engine is performed based on the amount of change of the temperature sensor. The quantity can be supplied appropriately. Here, if the operating state of the internal combustion engine can be known by a simplified system configuration in which the temperature sensor is omitted, a considerable cost reduction can be naturally attained.

However, conventionally, a temperature sensor is an essential component, and without a signal input from the temperature sensor, it is impossible to appropriately supply a fuel injection amount and obtain a stable operating state when starting the internal combustion engine. Met.

Accordingly, the present invention has been made to solve such a problem. In a simplified system configuration having no temperature sensor, the present invention provides a method for starting an internal combustion engine.
It is an object of the present invention to provide a fuel injection control device for an internal combustion engine capable of appropriately supplying a fuel injection amount and obtaining a stable operation state.

[0006]

According to the fuel injection control device for an internal combustion engine of the first aspect, when the internal combustion engine is started by the fuel injection control means, the engine speed is increased to a predetermined engine speed or more. A predetermined fuel injection amount is sequentially increased and supplied according to the elapsed time. As a result, when starting the internal combustion engine, the fuel injection amount is supplied without any excess or shortage, so that the operation state in starting the internal combustion engine can be stabilized, and a reliable start can be achieved.

In the fuel injection control device for an internal combustion engine according to the second aspect, the predetermined fuel injection amount is a fuel injection amount after the completion of warming-up, that is, a fuel injection amount necessary for starting the internal combustion engine regardless of a temperature state at the time of starting the internal combustion engine. A minimum fuel injection amount is set. Thus, it is possible to prevent, for example, fogging of the spark plug and deterioration of emission due to an excessive amount of fuel injection at the start of the internal combustion engine.

In the fuel injection control device of the fuel injection control device for an internal combustion engine according to the third aspect, the predetermined fuel injection amount is increased stepwise or continuously in accordance with the elapsed time, so that the fuel injection control means at the time of starting the internal combustion engine. Regardless of the temperature state, the optimal fuel injection amount is set at that time, and reliable starting can be achieved.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on examples.

FIG. 1 is a schematic configuration diagram showing an internal combustion engine to which a fuel injection control device for an internal combustion engine according to one embodiment of the present invention is applied and peripheral devices thereof.

In FIG. 1, reference numeral 1 denotes an internal combustion engine (engine).
The air from the air cleaner 3 is introduced into the intake passage 2 of the internal combustion engine 1. A throttle valve 11 which is opened and closed in conjunction with operation of an accelerator pedal (not shown) is provided in the intake passage 2. By opening and closing the throttle valve 11, the amount of intake air (intake air amount) to the intake passage 2 is adjusted. Simultaneously with the intake air amount, the internal combustion engine 1 is provided with an intake passage 2 near the intake port 4.
The fuel is injected and supplied from an injector (fuel injection valve) 5 provided in the fuel cell. Then, an air-fuel mixture composed of a predetermined fuel amount and an intake amount is sucked into the combustion chamber 7 through the intake valve 6.

A downstream side of a throttle valve 11 provided in the intake passage 2 has an intake pressure P in the intake passage 2.
An intake pressure sensor 21 for detecting M is provided. The crankshaft 12 of the internal combustion engine 1 is provided with a crank angle sensor 22 for detecting a crank angle [° CA (Crank Angle)] accompanying the rotation. The internal combustion engine 1 according to the crank angle detected by the crank angle sensor 22
Is calculated.

Further, an ignition plug 13 is provided toward the inside of the combustion chamber 7 of the internal combustion engine 1. The ignition plug 13 receives a high signal from the ignition coil / igniter 14 based on an ignition command signal output from an electronic control unit (ECU) 30 described later in synchronization with the crank angle detected by the crank angle sensor 22. A voltage is applied, and ignition combustion of the air-fuel mixture in the combustion chamber 7 is performed. In this manner, the air-fuel mixture in the combustion chamber 7 is burned (expanded) to obtain a driving force, and the exhaust gas after the combustion is led out of the exhaust manifold through the exhaust valve 8 to the exhaust passage 9 and discharged to the outside. You.

The ECU 30 includes a CPU 31 serving as a central processing unit for executing various known arithmetic processing, a ROM 32 storing a control program, and a RAM 3 storing various data.
3, B / U (backup) RAM 34, input / output circuit 3
5 and a logical operation circuit including a bus line 36 connecting them. This ECU 30 includes:
The intake pressure PM from the intake pressure sensor 21, the crank angle from the crank angle sensor 22, and the like are input. Based on output signals from the ECU 30 based on these various sensor information, the injector 5 related to the fuel injection timing and the fuel injection amount, the ignition coil / igniter 14 related to the ignition timing of the ignition plug 13 and the like are appropriately controlled.

Next, an EC used in a fuel injection control device for an internal combustion engine according to an embodiment of the present invention will be described.
Referring to FIG. 3, a description will be given of a processing procedure of the fuel injection control at the time of starting in the CPU 31 in the U30 with reference to FIG. Here, FIG. 3 shows the engine speed N at the start.
5 is a time chart showing a transition state of a fuel injection pulse width TSTA according to E [rpm]. Note that this start-time fuel injection control routine is repeatedly executed by the CPU 31 for each combustion cycle of each cylinder of the internal combustion engine 1.

In FIG. 2, first, in step S101,
It is determined whether it is the first fuel injection timing. When the determination condition of step S101 is satisfied, the process proceeds to step S102, and the starting fuel injection pulse width TSTA0 for the initial setting corresponding to the fuel injection amount after the completion of warm-up stored in the ROM 32 is set to the starting fuel injection. The pulse width is set to TSTA. On the other hand, step S
If the determination condition of 101 is not satisfied, that is, if it is not the first fuel injection timing, the process proceeds to step S103,
The previous startup fuel injection pulse width TSTAO is set to the current startup fuel injection pulse width TSTA.

Step S102 or step S103
The process proceeds to step S104, and the engine speed NE is read. Next, the process proceeds to step S105, and it is determined whether the engine speed NE read in step S104 is less than a predetermined engine speed NESTA. Here, the predetermined engine speed NESTA is set slightly lower than the idle speed, and when the internal combustion engine 1 is started by cranking the ignition switch (not shown) “ON”, the engine speed NESTA is set. Is lower than the predetermined engine speed NESTA (at time t0 shown in FIG. 3).
To time t1) at "starting time", and when the engine speed NE becomes higher than the predetermined engine speed NESTA and it can be considered that the engine has started (time t1 shown in FIG. 3) and thereafter, "after starting". Say

When the condition of step S105 is satisfied, that is, when the engine speed NE is lower than the predetermined engine speed NESTA and the internal combustion engine 1 is at the start, step S1 is executed.
The process proceeds to 06, and it is determined whether the number of times of fuel injection at start NST is equal to or greater than a predetermined number of times N set in advance. Step S
106 is satisfied, that is, the number of fuel injections at the start N
If the engine speed NE is lower than the predetermined engine speed NESTA despite the fact that the ST is a predetermined number N or more, the process proceeds to step S107, and it is determined that the fuel injection amount is insufficient and the start is not completed. Injection pulse width TST
The predetermined pulse width TW is added to A, and the starting fuel injection pulse width TSTA is updated. As shown in FIG. 3, the starting fuel injection pulse width TSTA at this time is increased stepwise according to the elapsed time from the initially set starting fuel injection pulse width TSTA0.

On the other hand, when the determination condition of step S106 is not satisfied, that is, when the number of times of fuel injection NST at start is less than the predetermined number N, step S107 is skipped. Next, the routine proceeds to step S108, where the current startup fuel injection pulse width TSTAO is stored in the RAM 33 as the startup fuel injection pulse width TSTAO for the next time, and this routine ends.

In this manner, the fuel injection amount based on the fuel injection pulse width TSTA at the start and the number NST of fuel injections at the start set in the processing of this routine is such that the engine speed NE is equal to or greater than the predetermined engine speed NESTA. Until the cylinders of the internal combustion engine 1 are appropriately increased in quantity, and injected from the injectors 5.

On the other hand, the condition for determination in step S105 is not satisfied, that is, the engine speed NE becomes the predetermined engine speed NEST.
A, and when the internal combustion engine 1 has been started, the process proceeds to step S109, and the post-start fuel injection correction coefficient FS
After E is calculated, this routine ends. The post-start fuel injection correction coefficient FSE is a total fuel injection at start which is an integral value of the start fuel injection pulse width TSTA, the start fuel injection number NST, the start fuel injection pulse width TSTA, and the start fuel injection number NST. It is calculated based on the amount and the like.

When the post-start fuel injection correction coefficient FSE is calculated by the above-described routine, the routine proceeds to a not-shown main routine after start, and as is well known, the engine speed NE and load of the internal combustion engine 1 as the load are calculated. The basic fuel injection amount calculated based on the intake pressure PM is the post-start fuel injection correction coefficient F
The fuel injection amount supplied from the injector 5 is adjusted by increasing the amount using the SE, and the fuel injection amount is adjusted.

As described above, the fuel injection control device for an internal combustion engine according to the present embodiment includes a crank angle sensor 22 as a rotation speed detecting means for detecting the engine speed NE of the internal combustion engine 1 and Until the engine speed NE becomes equal to or higher than the predetermined engine speed NESTA, the ECU 30 sequentially increases and supplies a predetermined fuel injection amount based on the initially set fuel injection pulse width TSTA0 according to the elapsed time.
And a fuel injection control means achieved by the CPU 31.

That is, when the internal combustion engine 1 is started, the initially set fuel injection pulse width TSTA at the time of starting is set until the engine speed NE becomes higher than or equal to the predetermined engine speed NESTA.
The predetermined fuel injection amount based on 0 is sequentially changed according to the elapsed time,
The amount is increased and injected and supplied. As a result, when the internal combustion engine 1 is started, even if the system configuration is simplified without the temperature sensor, the fuel injection amount is supplied without any excess and deficiency. Stabilization and thus reliable starting can be achieved.

Further, the fuel injection control device for an internal combustion engine according to the present embodiment uses a predetermined fuel injection amount based on the fuel injection pulse width TSTA0 at the time of starting as the fuel injection amount after the internal combustion engine 1 is completely warmed up. is there. That is, as the initially set predetermined fuel injection amount, the fuel injection amount after the completion of warm-up, that is, regardless of the temperature state at the time of starting the internal combustion engine 1,
The minimum fuel injection amount required for starting is set. As a result, it is possible to prevent, for example, fogging of the spark plug 13 and deterioration of emission due to too much fuel injection amount at the time of starting the internal combustion engine.

The fuel injection control means, which is achieved by the CPU 31 in the ECU 30 of the fuel injection control device for an internal combustion engine of this embodiment, sets a predetermined fuel injection amount based on the starting fuel injection pulse width TSTA0 to the elapsed time. The amount is gradually increased accordingly. That is, the predetermined fuel injection amount is increased stepwise according to the elapsed time based on the starting fuel injection pulse width TSTA and the starting fuel injection frequency NST. Thereby, regardless of the temperature state at the time of starting the internal combustion engine 1, an optimal fuel injection amount is set at that time, and a reliable start can be achieved.

In the above embodiment, the starting fuel injection pulse width TSTA is increased stepwise according to the elapsed time, and the fuel injection amount is increased based thereon. Equal pitch or unequal pitch may be used. Further, when the present invention is carried out, the present invention is not limited to this stepwise increase, and as shown by a dashed line in FIG. The same operation and effect can be expected even if the fuel injection amount is increased by increasing the fuel injection amount.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an internal combustion engine to which a fuel injection control device for an internal combustion engine according to an embodiment of the present invention is applied, and peripheral devices thereof.

FIG. 2 is an ECU used in a fuel injection control device for an internal combustion engine according to one embodiment of the present invention.
4 is a flowchart showing a processing procedure of fuel injection control at start-up in a CPU of the first embodiment.

FIG. 3 is a time chart showing a transition state of a fuel injection pulse width corresponding to the processing of FIG. 2;

[Explanation of symbols]

 Reference Signs List 1 internal combustion engine 21 intake pressure sensor 22 crank angle sensor 30 ECU (electronic control unit)

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3G084 BA13 CA01 DA13 EB12 EB16 EC02 FA11 FA36 FA39 3G301 HA01 JA20 KA01 LA01 LB02 LC01 MA13 NA07 ND02 ND42 NE01 PA07Z PB03A PE01A PE01Z PE04Z PF16Z

Claims (3)

[Claims] A first fuel injection means for detecting an engine speed of the internal combustion engine; and a predetermined fuel injection initially set until the engine speed becomes equal to or higher than a predetermined engine speed when the internal combustion engine is started. A fuel injection control device for an internal combustion engine, comprising: fuel injection control means for sequentially increasing and injecting an amount in accordance with an elapsed time. 2. The fuel injection control device for an internal combustion engine according to claim 1, wherein the predetermined fuel injection amount is a fuel injection amount after completion of warm-up of the internal combustion engine. 3. The internal combustion engine according to claim 1, wherein the fuel injection control means increases the predetermined fuel injection amount stepwise or continuously according to an elapsed time. Engine fuel injection control device.