JPS611841A - Fuel injection device for internal-combustion engine - Google Patents

Abstract

PURPOSE:To enhance starting performance by detecting the concentration of an unburned gas component of fuel caused by the remainder or leakage in an air suction pipe, and by determining the fuel supply quantity at the time of start-up in response to the concentration. CONSTITUTION:HC concentration out of the unburned gas components caused by fuel leaking from the valve part of nozzle part 2 of fuel injection valve 1 and remaining fuel, etc. is detected by an HC sensor 4, and total quantity of unburned gas is to be estimated. Further, a CO sensor may be used as for the unburned gas detecting sensor. In response to the concentration of unburned gas component of fuel thus detected, the supply quantity of fuel at the time of start- up is determined. Thus, the starting performance can be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel injection device for an internal combustion engine, and more particularly to a starting device that can improve starting performance.

[Prior art]

In spark ignition internal combustion engines, the startability of the engine is usually improved by increasing the air-fuel mixture concentration when starting the engine.

In this case, a system is known in which a sufficiently rich mixture is supplied when the engine temperature is low, and the mixture concentration is gradually reduced as the engine temperature rises after the engine is started. ing.

On the other hand, in order to improve startability, improve exhaust emissions, and improve safety, it is necessary to reduce fuel leakage from the valve part of the fuel injection valve, but conventional processing techniques for valve parts and metal surfaces due to the structure are necessary. Due to the seal, it is difficult to completely eliminate fuel leakage from the valve part. Furthermore, it is insufficient to know the amount of fuel that is injected and remains after the engine is stopped. As a result, the air-fuel ratio of the air-fuel mixture becomes excessive, which may prolong the engine starting time or cause the engine to fall out of the flammable range and cause a misfire, resulting in the engine stalling.

[Purpose of the invention]

In view of the above points, an object of the present invention is to detect the concentration of unburned gas components due to leaked fuel from the valve part of a fuel injection valve or residual fuel before starting the engine, and to detect the concentration of unburned gas components at the time of engine starting according to the detected concentration. An object of the present invention is to provide a fuel injection device for an internal combustion engine that can further improve startability and purify exhaust gas by adjusting the amount of fuel supplied.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, ``■'' is a fuel injection valve arranged for each cylinder of the engine, and has a nozzle hole 2 at its tip.

Reference numeral 3 denotes a fuel injection valve 3 for increasing the amount at startup, which is generally operated together with the fuel injection valve 1 only at the time of startup, and is disposed on the upstream side of the gathering portion of each intake pipe 5 and closer to the throttle valve 6. Reference numeral 4 denotes an HC sensor, which is arranged in each intake pipe 5 or in a gathering part thereof.
The total amount of unburned gas is estimated by detecting the HC concentration of the unburned gas components caused by fuel leaked from the valve part and residual fuel. Note that a CO sensor or the like may be used instead of the HC sensor as the unburned gas detection sensor. 7 is an intake valve, 8.9 is a fuel injection valve 1.
3 is a drive circuit, and 100 is a control circuit, which inputs various parameters such as engine rotational speed N, intake air amount Q, intake air temperature TA, and cooling water temperature Tw from sensors placed in various parts, and calculates the optimum value for the engine. It calculates the fuel injection amount at startup and during normal operation, and controls each fuel injection valve 1.3. This control circuit 10o is composed of a digital circuit including a microcomputer, and operates according to a predetermined program.

By the way, when detecting the amount of unburned gas filling the intake pipe, it is necessary to detect the amount of unburned gas that is already present at least when the engine is started.
In order for the amount of unburned gas to be detected, the timing for detecting the amount of unburned gas must be set before starting the engine. This can be done just before starting, or right after the engine stopped last time.

In the former case, the ignition switch (IG/SW
) is detected during the period from turning on the starter switch (ST/SW) to actuation of the starter switch (ST/SW), or it can be detected during the period from immediately after the driver gets in the car until turning on the ignition switch (IG-3W). In the latter case, by providing a bank-up power supply means that can supply power to the control circuit 10° even after the ignition switch (IG-3W) is shut off, detection can be made during that predetermined time. .

Therefore, the control circuit 1o takes the above points into consideration.

Explain how it works. FIG. 2 shows an example in which the degree of HCl is detected during the period from turning on the ignition switch (IG-3W) to starting the starter.

First, by turning on the ignition switch (IG-3W), each coefficient t! , t2 are initialized (step (20,
1) Immediately thereafter, the HC sensor 4 is activated (stabilized) for a predetermined period of time β and a detection operation is performed (steps 202 to 2o4). HC concentration detection processing is performed after a predetermined time β (step 205), and it is determined whether the HC concentration is equal to or higher than a set value (steps 206 to 208).

Then, detectable engine parameters (cooling water temperature, intake air temperature, etc.) are read (step 209), and in step 210, the start inch (
It is determined whether or not it is time to start the engine based on whether or not ST-3W) is turned on. If the engine has not yet been started, the HC concentration detection process is repeated via step 211. On the other hand, when the engine is started, the starting injection amount (pulse width Ti5t) is determined based on the previously read engine parameters. In step 212), during the predetermined time α, the starting injection amount T ist is reduced and corrected according to the previously determined HC concentration, and the fuel is injected from the fuel injection valve 1 or 3 (steps 213 to 21).
8). In other words, when the HC concentration is higher than the set value (HC=1
), the injection amount Ti5t is multiplied by (0<K<1) to make a reduction correction, and when it is less than the set value (HC=O), no reduction correction is made. Therefore, since this process is performed until t2-α, the injection amount is corrected to be reduced by (1-K)·Ti5t·α in total. Therefore, it is possible to effectively prevent the air-fuel ratio of the air-fuel mixture in the intake pipe from becoming excessive.

Then, when the engine starts, steps 210 and 211
The process then proceeds to steps 219 and 220, where conventionally known fuel injection amount calculation processing and injection control are performed.

In the above embodiment, the reduction correction is performed in two states: whether the HC concentration is equal to or higher than the set value, but it is also possible to perform stepwise reduction correction in three or more states. A reduction correction coefficient K corresponding to the engine speed may be stored in a map in advance, and the coefficient K may be read out in accordance with the detected HC concentration to correct the fuel injection amount at the time of starting.

Further, FIGS. 3 and 4 show other embodiments of the present invention. First, in Fig. 3, a door switch is installed on the driver's side door of a car, or a seat switch is installed on the driver's seat, and when the switch is turned on, the HC sensor 4 is automatically activated, and the ignition switch (IG- 3W) is ON
Then, the HC concentration detection process is performed.

Further, if the sensor operation continues for a predetermined time T or more after the detection switch is turned on, the sensor operation is forcibly stopped. This prevents the sensor from operating continuously if the door is simply opened but the engine is not started.

Further, FIG. 4 shows an example in which HO2 degrees are detected immediately after the engine is stopped and stored in a non-volatile memory that is powered by a power bank.

〔Effect of the invention〕

As described above, in the present invention, the concentration of unburned gas components remaining in the intake pipe or due to leakage is detected before starting the engine, and the amount of fuel supplied at the time of engine starting is adjusted according to the detected concentration. By setting the air-fuel mixture to the optimum air-fuel ratio, starting performance can be further improved and exhaust purification can be achieved.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of an engine control system, FIG. 2 is a flow chart showing one embodiment of the present invention, and FIGS. 3 and 4 are flow charts showing other embodiments of the present invention. 1.3...Fuel injection valve, 2...Nozzle hole portion, 4...HC sensor serving as the first sensor, 5...Intake pipe, 6...
- Throttle valve, 100... control circuit.

Claims (1)

[Claims] a first sensor that detects the concentration of unburned gas components filling an intake pipe of an internal combustion engine; a second sensor that detects the operating state of the engine; and at least a signal from the first sensor before starting the engine. and a control means for detecting the concentration of unburned gas components and correcting the starting fuel supply amount determined by the second sensor in accordance with the detected concentration when starting the engine. Engine fuel injection system.